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Revision 1.215 by root, Tue Jun 23 12:19:33 2009 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 and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	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	55	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,	56	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,	57	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	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	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	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	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	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	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	69	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	70	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	71	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	72	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.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	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	77	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,	78	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	79	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	80	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	81	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).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	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	85	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	86	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	87	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	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	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	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70
71		100
72	=head1 DESCRIPTION	101	=head1 DESCRIPTION
73		102
74	L<AnyEvent> provides an identical interface to multiple event loops. This	103	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	104	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	108	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	109	module.
81		110
82	During the first call of any watcher-creation method, the module tries	111	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	112	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	113	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,	114	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	115	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Event::Lib, Qt and POE as the pure perl	116	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	117	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	118	be successfully loaded will be used. If, after this, still none could be
90	found, AnyEvent will fall back to a pure-perl event loop, which is not	119	found, AnyEvent will fall back to a pure-perl event loop, which is not
91	very efficient, but should work everywhere.	120	very efficient, but should work everywhere.
92		121
…		…
103	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
104	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
105		134
106	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
109		138
110	=head1 WATCHERS	139	=head1 WATCHERS
111		140
112	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
115		144
116	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
119	is in control).	148	is in control).
120		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
121	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
122	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
123	to it).	158	to it).
124		159
125	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
127	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
128	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
129		164
130	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
131		166
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
134	undef $w;	169	undef $w;
135	});	170	});
136		171
137	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
138	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
139	declared.	174	declared.
140		175
141	=head2 IO WATCHERS	176	=head2 I/O WATCHERS
142		177
143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
145		180
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
147	events. C<poll> must be a string that is either C<r> or C<w>, which	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
148	creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
149	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
150	becomes ready.
151		192
152	As long as the I/O watcher exists it will keep the file descriptor or a	193	Although the callback might get passed parameters, their value and
153	copy of it alive/open.	194	presence is undefined and you cannot rely on them. Portable AnyEvent
		195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
		197	The I/O watcher might use the underlying file descriptor or a copy of it.
155	It is not allowed to close a file handle as long as any watcher is active	198	You must not close a file handle as long as any watcher is active on the
156	on the underlying file descriptor.	199	underlying file descriptor.
157		200
158	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
159	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
160	handles.	203	handles.
161		204
162	Example:
163
164	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
165	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
166	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
167	warn "read: $input\n";	210	warn "read: $input\n";
168	undef $w;	211	undef $w;
169	});	212	});
…		…
172		215
173	You can create a time watcher by calling the C<< AnyEvent->timer >>	216	You can create a time watcher by calling the C<< AnyEvent->timer >>
174	method with the following mandatory arguments:	217	method with the following mandatory arguments:
175		218
176	C<after> specifies after how many seconds (fractional values are	219	C<after> specifies after how many seconds (fractional values are
177	supported) should the timer activate. C<cb> the callback to invoke in that	220	supported) the callback should be invoked. C<cb> is the callback to invoke
178	case.	221	in that case.
179		222
180	The timer callback will be invoked at most once: if you want a repeating	223	Although the callback might get passed parameters, their value and
181	timer you have to create a new watcher (this is a limitation by both Tk	224	presence is undefined and you cannot rely on them. Portable AnyEvent
182	and Glib).	225	callbacks cannot use arguments passed to time watcher callbacks.
183		226
184	Example:	227	The callback will normally be invoked once only. If you specify another
		228	parameter, C<interval>, as a strictly positive number (> 0), then the
		229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
185		232
		233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
		236
186	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
187	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
188	warn "timeout\n";	240	warn "timeout\n";
189	});	241	});
190		242
191	# to cancel the timer:	243	# to cancel the timer:
192	undef $w;	244	undef $w;
193		245
194	Example 2:
195
196	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
197	my $w;
198		247
199	my $cb = sub {
200	# cancel the old timer while creating a new one
201	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
202	};	250	};
203
204	# start the "loop" by creating the first watcher
205	$w = AnyEvent->timer (after => 0.5, cb => $cb);
206		251
207	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
208		253
209	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
210	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
222	timers.	267	timers.
223		268
224	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
225	AnyEvent API.	270	AnyEvent API.
226		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
227	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
228		351
229	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
230	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
231	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
232		355
		356	Although the callback might get passed parameters, their value and
		357	presence is undefined and you cannot rely on them. Portable AnyEvent
		358	callbacks cannot use arguments passed to signal watcher callbacks.
		359
233	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
234	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
235	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
236	but it is guarenteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
237		364
238	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
239	between multiple watchers.	366	between multiple watchers.
240		367
241	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
248	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
249		376
250	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
251		378
252	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
253	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
254	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
255	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
256	and exit status (as returned by waitpid).
257		383
258	Example: wait for pid 1333	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
259		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
		392
		393	There is a slight catch to child watchers, however: you usually start them
		394	I<after> the child process was created, and this means the process could
		395	have exited already (and no SIGCHLD will be sent anymore).
		396
		397	Not all event models handle this correctly (POE doesn't), but even for
		398	event models that I<do> handle this correctly, they usually need to be
		399	loaded before the process exits (i.e. before you fork in the first place).
		400
		401	This means you cannot create a child watcher as the very first thing in an
		402	AnyEvent program, you I<have> to create at least one watcher before you
		403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
		404
		405	Example: fork a process and wait for it
		406
		407	my $done = AnyEvent->condvar;
		408
		409	my $pid = fork or exit 5;
		410
260	my $w = AnyEvent->child (	411	my $w = AnyEvent->child (
261	pid => 1333,	412	pid => $pid,
262	cb => sub {	413	cb => sub {
263	my ($pid, $status) = @_;	414	my ($pid, $status) = @_;
264	warn "pid $pid exited with status $status";	415	warn "pid $pid exited with status $status";
		416	$done->send;
265	},	417	},
266	);	418	);
		419
		420	# do something else, then wait for process exit
		421	$done->recv;
		422
		423	=head2 IDLE WATCHERS
		424
		425	Sometimes there is a need to do something, but it is not so important
		426	to do it instantly, but only when there is nothing better to do. This
		427	"nothing better to do" is usually defined to be "no other events need
		428	attention by the event loop".
		429
		430	Idle watchers ideally get invoked when the event loop has nothing
		431	better to do, just before it would block the process to wait for new
		432	events. Instead of blocking, the idle watcher is invoked.
		433
		434	Most event loops unfortunately do not really support idle watchers (only
		435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		436	will simply call the callback "from time to time".
		437
		438	Example: read lines from STDIN, but only process them when the
		439	program is otherwise idle:
		440
		441	my @lines; # read data
		442	my $idle_w;
		443	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		444	push @lines, scalar <STDIN>;
		445
		446	# start an idle watcher, if not already done
		447	$idle_w ||= AnyEvent->idle (cb => sub {
		448	# handle only one line, when there are lines left
		449	if (my $line = shift @lines) {
		450	print "handled when idle: $line";
		451	} else {
		452	# otherwise disable the idle watcher again
		453	undef $idle_w;
		454	}
		455	});
		456	});
267		457
268	=head2 CONDITION VARIABLES	458	=head2 CONDITION VARIABLES
269		459
		460	If you are familiar with some event loops you will know that all of them
		461	require you to run some blocking "loop", "run" or similar function that
		462	will actively watch for new events and call your callbacks.
		463
		464	AnyEvent is different, it expects somebody else to run the event loop and
		465	will only block when necessary (usually when told by the user).
		466
		467	The instrument to do that is called a "condition variable", so called
		468	because they represent a condition that must become true.
		469
270	Condition variables can be created by calling the C<< AnyEvent->condvar >>	470	Condition variables can be created by calling the C<< AnyEvent->condvar
271	method without any arguments.	471	>> method, usually without arguments. The only argument pair allowed is
272		472
273	A condition variable waits for a condition - precisely that the C<<	473	C<cb>, which specifies a callback to be called when the condition variable
274	->broadcast >> method has been called.	474	becomes true, with the condition variable as the first argument (but not
		475	the results).
275		476
276	They are very useful to signal that a condition has been fulfilled, for	477	After creation, the condition variable is "false" until it becomes "true"
		478	by calling the C<send> method (or calling the condition variable as if it
		479	were a callback, read about the caveats in the description for the C<<
		480	->send >> method).
		481
		482	Condition variables are similar to callbacks, except that you can
		483	optionally wait for them. They can also be called merge points - points
		484	in time where multiple outstanding events have been processed. And yet
		485	another way to call them is transactions - each condition variable can be
		486	used to represent a transaction, which finishes at some point and delivers
		487	a result.
		488
		489	Condition variables are very useful to signal that something has finished,
277	example, if you write a module that does asynchronous http requests,	490	for example, if you write a module that does asynchronous http requests,
278	then a condition variable would be the ideal candidate to signal the	491	then a condition variable would be the ideal candidate to signal the
279	availability of results.	492	availability of results. The user can either act when the callback is
		493	called or can synchronously C<< ->recv >> for the results.
280		494
281	You can also use condition variables to block your main program until	495	You can also use them to simulate traditional event loops - for example,
282	an event occurs - for example, you could C<< ->wait >> in your main	496	you can block your main program until an event occurs - for example, you
283	program until the user clicks the Quit button in your app, which would C<<	497	could C<< ->recv >> in your main program until the user clicks the Quit
284	->broadcast >> the "quit" event.	498	button of your app, which would C<< ->send >> the "quit" event.
285		499
286	Note that condition variables recurse into the event loop - if you have	500	Note that condition variables recurse into the event loop - if you have
287	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	501	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
288	lose. Therefore, condition variables are good to export to your caller, but	502	lose. Therefore, condition variables are good to export to your caller, but
289	you should avoid making a blocking wait yourself, at least in callbacks,	503	you should avoid making a blocking wait yourself, at least in callbacks,
290	as this asks for trouble.	504	as this asks for trouble.
291		505
292	This object has two methods:	506	Condition variables are represented by hash refs in perl, and the keys
		507	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		508	easy (it is often useful to build your own transaction class on top of
		509	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		510	it's C<new> method in your own C<new> method.
		511
		512	There are two "sides" to a condition variable - the "producer side" which
		513	eventually calls C<< -> send >>, and the "consumer side", which waits
		514	for the send to occur.
		515
		516	Example: wait for a timer.
		517
		518	# wait till the result is ready
		519	my $result_ready = AnyEvent->condvar;
		520
		521	# do something such as adding a timer
		522	# or socket watcher the calls $result_ready->send
		523	# when the "result" is ready.
		524	# in this case, we simply use a timer:
		525	my $w = AnyEvent->timer (
		526	after => 1,
		527	cb => sub { $result_ready->send },
		528	);
		529
		530	# this "blocks" (while handling events) till the callback
		531	# calls send
		532	$result_ready->recv;
		533
		534	Example: wait for a timer, but take advantage of the fact that
		535	condition variables are also code references.
		536
		537	my $done = AnyEvent->condvar;
		538	my $delay = AnyEvent->timer (after => 5, cb => $done);
		539	$done->recv;
		540
		541	Example: Imagine an API that returns a condvar and doesn't support
		542	callbacks. This is how you make a synchronous call, for example from
		543	the main program:
		544
		545	use AnyEvent::CouchDB;
		546
		547	...
		548
		549	my @info = $couchdb->info->recv;
		550
		551	And this is how you would just ste a callback to be called whenever the
		552	results are available:
		553
		554	$couchdb->info->cb (sub {
		555	my @info = $_[0]->recv;
		556	});
		557
		558	=head3 METHODS FOR PRODUCERS
		559
		560	These methods should only be used by the producing side, i.e. the
		561	code/module that eventually sends the signal. Note that it is also
		562	the producer side which creates the condvar in most cases, but it isn't
		563	uncommon for the consumer to create it as well.
293		564
294	=over 4	565	=over 4
295		566
		567	=item $cv->send (...)
		568
		569	Flag the condition as ready - a running C<< ->recv >> and all further
		570	calls to C<recv> will (eventually) return after this method has been
		571	called. If nobody is waiting the send will be remembered.
		572
		573	If a callback has been set on the condition variable, it is called
		574	immediately from within send.
		575
		576	Any arguments passed to the C<send> call will be returned by all
		577	future C<< ->recv >> calls.
		578
		579	Condition variables are overloaded so one can call them directly
		580	(as a code reference). Calling them directly is the same as calling
		581	C<send>. Note, however, that many C-based event loops do not handle
		582	overloading, so as tempting as it may be, passing a condition variable
		583	instead of a callback does not work. Both the pure perl and EV loops
		584	support overloading, however, as well as all functions that use perl to
		585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		586	example).
		587
		588	=item $cv->croak ($error)
		589
		590	Similar to send, but causes all call's to C<< ->recv >> to invoke
		591	C<Carp::croak> with the given error message/object/scalar.
		592
		593	This can be used to signal any errors to the condition variable
		594	user/consumer.
		595
		596	=item $cv->begin ([group callback])
		597
296	=item $cv->wait	598	=item $cv->end
297		599
298	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	600	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		601
		602	These two methods can be used to combine many transactions/events into
		603	one. For example, a function that pings many hosts in parallel might want
		604	to use a condition variable for the whole process.
		605
		606	Every call to C<< ->begin >> will increment a counter, and every call to
		607	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		608	>>, the (last) callback passed to C<begin> will be executed. That callback
		609	is I<supposed> to call C<< ->send >>, but that is not required. If no
		610	callback was set, C<send> will be called without any arguments.
		611
		612	Let's clarify this with the ping example:
		613
		614	my $cv = AnyEvent->condvar;
		615
		616	my %result;
		617	$cv->begin (sub { $cv->send (\%result) });
		618
		619	for my $host (@list_of_hosts) {
		620	$cv->begin;
		621	ping_host_then_call_callback $host, sub {
		622	$result{$host} = ...;
		623	$cv->end;
		624	};
		625	}
		626
		627	$cv->end;
		628
		629	This code fragment supposedly pings a number of hosts and calls
		630	C<send> after results for all then have have been gathered - in any
		631	order. To achieve this, the code issues a call to C<begin> when it starts
		632	each ping request and calls C<end> when it has received some result for
		633	it. Since C<begin> and C<end> only maintain a counter, the order in which
		634	results arrive is not relevant.
		635
		636	There is an additional bracketing call to C<begin> and C<end> outside the
		637	loop, which serves two important purposes: first, it sets the callback
		638	to be called once the counter reaches C<0>, and second, it ensures that
		639	C<send> is called even when C<no> hosts are being pinged (the loop
		640	doesn't execute once).
		641
		642	This is the general pattern when you "fan out" into multiple subrequests:
		643	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		644	is called at least once, and then, for each subrequest you start, call
		645	C<begin> and for each subrequest you finish, call C<end>.
		646
		647	=back
		648
		649	=head3 METHODS FOR CONSUMERS
		650
		651	These methods should only be used by the consuming side, i.e. the
		652	code awaits the condition.
		653
		654	=over 4
		655
		656	=item $cv->recv
		657
		658	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
299	called on c<$cv>, while servicing other watchers normally.	659	>> methods have been called on c<$cv>, while servicing other watchers
		660	normally.
300		661
301	You can only wait once on a condition - additional calls will return	662	You can only wait once on a condition - additional calls are valid but
302	immediately.	663	will return immediately.
		664
		665	If an error condition has been set by calling C<< ->croak >>, then this
		666	function will call C<croak>.
		667
		668	In list context, all parameters passed to C<send> will be returned,
		669	in scalar context only the first one will be returned.
303		670
304	Not all event models support a blocking wait - some die in that case	671	Not all event models support a blocking wait - some die in that case
305	(programs might want to do that to stay interactive), so I<if you are	672	(programs might want to do that to stay interactive), so I<if you are
306	using this from a module, never require a blocking wait>, but let the	673	using this from a module, never require a blocking wait>, but let the
307	caller decide whether the call will block or not (for example, by coupling	674	caller decide whether the call will block or not (for example, by coupling
308	condition variables with some kind of request results and supporting	675	condition variables with some kind of request results and supporting
309	callbacks so the caller knows that getting the result will not block,	676	callbacks so the caller knows that getting the result will not block,
310	while still suppporting blocking waits if the caller so desires).	677	while still supporting blocking waits if the caller so desires).
311		678
312	Another reason I<never> to C<< ->wait >> in a module is that you cannot	679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
313	sensibly have two C<< ->wait >>'s in parallel, as that would require	680	sensibly have two C<< ->recv >>'s in parallel, as that would require
314	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
315	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	682	can supply.
316	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
317	from different coroutines, however).
318		683
319	=item $cv->broadcast	684	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		685	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		686	versions and also integrates coroutines into AnyEvent, making blocking
		687	C<< ->recv >> calls perfectly safe as long as they are done from another
		688	coroutine (one that doesn't run the event loop).
320		689
321	Flag the condition as ready - a running C<< ->wait >> and all further	690	You can ensure that C<< -recv >> never blocks by setting a callback and
322	calls to C<wait> will (eventually) return after this method has been	691	only calling C<< ->recv >> from within that callback (or at a later
323	called. If nobody is waiting the broadcast will be remembered..	692	time). This will work even when the event loop does not support blocking
		693	waits otherwise.
		694
		695	=item $bool = $cv->ready
		696
		697	Returns true when the condition is "true", i.e. whether C<send> or
		698	C<croak> have been called.
		699
		700	=item $cb = $cv->cb ($cb->($cv))
		701
		702	This is a mutator function that returns the callback set and optionally
		703	replaces it before doing so.
		704
		705	The callback will be called when the condition becomes "true", i.e. when
		706	C<send> or C<croak> are called, with the only argument being the condition
		707	variable itself. Calling C<recv> inside the callback or at any later time
		708	is guaranteed not to block.
324		709
325	=back	710	=back
326
327	Example:
328
329	# wait till the result is ready
330	my $result_ready = AnyEvent->condvar;
331
332	# do something such as adding a timer
333	# or socket watcher the calls $result_ready->broadcast
334	# when the "result" is ready.
335	# in this case, we simply use a timer:
336	my $w = AnyEvent->timer (
337	after => 1,
338	cb => sub { $result_ready->broadcast },
339	);
340
341	# this "blocks" (while handling events) till the watcher
342	# calls broadcast
343	$result_ready->wait;
344		711
345	=head1 GLOBAL VARIABLES AND FUNCTIONS	712	=head1 GLOBAL VARIABLES AND FUNCTIONS
346		713
347	=over 4	714	=over 4
348		715
…		…
354	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	721	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
355	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	722	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
356		723
357	The known classes so far are:	724	The known classes so far are:
358		725
359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
361	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	726	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
362	AnyEvent::Impl::Event based on Event, second best choice.	727	AnyEvent::Impl::Event based on Event, second best choice.
		728	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
363	AnyEvent::Impl::Glib based on Glib, third-best choice.	729	AnyEvent::Impl::Glib based on Glib, third-best choice.
364	AnyEvent::Impl::Tk based on Tk, very bad choice.	730	AnyEvent::Impl::Tk based on Tk, very bad choice.
365	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
366	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	731	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
367	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	732	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
368	AnyEvent::Impl::POE based on POE, not generic enough for full support.	733	AnyEvent::Impl::POE based on POE, not generic enough for full support.
369		734
370	There is no support for WxWidgets, as WxWidgets has no support for	735	There is no support for WxWidgets, as WxWidgets has no support for
…		…
382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	747	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
383	if necessary. You should only call this function right before you would	748	if necessary. You should only call this function right before you would
384	have created an AnyEvent watcher anyway, that is, as late as possible at	749	have created an AnyEvent watcher anyway, that is, as late as possible at
385	runtime.	750	runtime.
386		751
		752	=item $guard = AnyEvent::post_detect { BLOCK }
		753
		754	Arranges for the code block to be executed as soon as the event model is
		755	autodetected (or immediately if this has already happened).
		756
		757	If called in scalar or list context, then it creates and returns an object
		758	that automatically removes the callback again when it is destroyed. See
		759	L<Coro::BDB> for a case where this is useful.
		760
		761	=item @AnyEvent::post_detect
		762
		763	If there are any code references in this array (you can C<push> to it
		764	before or after loading AnyEvent), then they will called directly after
		765	the event loop has been chosen.
		766
		767	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		768	if it contains a true value then the event loop has already been detected,
		769	and the array will be ignored.
		770
		771	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		772
387	=back	773	=back
388		774
389	=head1 WHAT TO DO IN A MODULE	775	=head1 WHAT TO DO IN A MODULE
390		776
391	As a module author, you should C<use AnyEvent> and call AnyEvent methods	777	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
394	Be careful when you create watchers in the module body - AnyEvent will	780	Be careful when you create watchers in the module body - AnyEvent will
395	decide which event module to use as soon as the first method is called, so	781	decide which event module to use as soon as the first method is called, so
396	by calling AnyEvent in your module body you force the user of your module	782	by calling AnyEvent in your module body you force the user of your module
397	to load the event module first.	783	to load the event module first.
398		784
399	Never call C<< ->wait >> on a condition variable unless you I<know> that	785	Never call C<< ->recv >> on a condition variable unless you I<know> that
400	the C<< ->broadcast >> method has been called on it already. This is	786	the C<< ->send >> method has been called on it already. This is
401	because it will stall the whole program, and the whole point of using	787	because it will stall the whole program, and the whole point of using
402	events is to stay interactive.	788	events is to stay interactive.
403		789
404	It is fine, however, to call C<< ->wait >> when the user of your module	790	It is fine, however, to call C<< ->recv >> when the user of your module
405	requests it (i.e. if you create a http request object ad have a method	791	requests it (i.e. if you create a http request object ad have a method
406	called C<results> that returns the results, it should call C<< ->wait >>	792	called C<results> that returns the results, it should call C<< ->recv >>
407	freely, as the user of your module knows what she is doing. always).	793	freely, as the user of your module knows what she is doing. always).
408		794
409	=head1 WHAT TO DO IN THE MAIN PROGRAM	795	=head1 WHAT TO DO IN THE MAIN PROGRAM
410		796
411	There will always be a single main program - the only place that should	797	There will always be a single main program - the only place that should
…		…
413		799
414	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
415	do anything special (it does not need to be event-based) and let AnyEvent	801	do anything special (it does not need to be event-based) and let AnyEvent
416	decide which implementation to chose if some module relies on it.	802	decide which implementation to chose if some module relies on it.
417		803
418	If the main program relies on a specific event model. For example, in	804	If the main program relies on a specific event model - for example, in
419	Gtk2 programs you have to rely on the Glib module. You should load the	805	Gtk2 programs you have to rely on the Glib module - you should load the
420	event module before loading AnyEvent or any module that uses it: generally	806	event module before loading AnyEvent or any module that uses it: generally
421	speaking, you should load it as early as possible. The reason is that	807	speaking, you should load it as early as possible. The reason is that
422	modules might create watchers when they are loaded, and AnyEvent will	808	modules might create watchers when they are loaded, and AnyEvent will
423	decide on the event model to use as soon as it creates watchers, and it	809	decide on the event model to use as soon as it creates watchers, and it
424	might chose the wrong one unless you load the correct one yourself.	810	might chose the wrong one unless you load the correct one yourself.
425		811
426	You can chose to use a rather inefficient pure-perl implementation by	812	You can chose to use a pure-perl implementation by loading the
427	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
428	behaviour everywhere, but letting AnyEvent chose is generally better.	814	everywhere, but letting AnyEvent chose the model is generally better.
		815
		816	=head2 MAINLOOP EMULATION
		817
		818	Sometimes (often for short test scripts, or even standalone programs who
		819	only want to use AnyEvent), you do not want to run a specific event loop.
		820
		821	In that case, you can use a condition variable like this:
		822
		823	AnyEvent->condvar->recv;
		824
		825	This has the effect of entering the event loop and looping forever.
		826
		827	Note that usually your program has some exit condition, in which case
		828	it is better to use the "traditional" approach of storing a condition
		829	variable somewhere, waiting for it, and sending it when the program should
		830	exit cleanly.
		831
		832
		833	=head1 OTHER MODULES
		834
		835	The following is a non-exhaustive list of additional modules that use
		836	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		837	in the same program. Some of the modules come with AnyEvent, some are
		838	available via CPAN.
		839
		840	=over 4
		841
		842	=item L<AnyEvent::Util>
		843
		844	Contains various utility functions that replace often-used but blocking
		845	functions such as C<inet_aton> by event-/callback-based versions.
		846
		847	=item L<AnyEvent::Socket>
		848
		849	Provides various utility functions for (internet protocol) sockets,
		850	addresses and name resolution. Also functions to create non-blocking tcp
		851	connections or tcp servers, with IPv6 and SRV record support and more.
		852
		853	=item L<AnyEvent::Handle>
		854
		855	Provide read and write buffers, manages watchers for reads and writes,
		856	supports raw and formatted I/O, I/O queued and fully transparent and
		857	non-blocking SSL/TLS.
		858
		859	=item L<AnyEvent::DNS>
		860
		861	Provides rich asynchronous DNS resolver capabilities.
		862
		863	=item L<AnyEvent::HTTP>
		864
		865	A simple-to-use HTTP library that is capable of making a lot of concurrent
		866	HTTP requests.
		867
		868	=item L<AnyEvent::HTTPD>
		869
		870	Provides a simple web application server framework.
		871
		872	=item L<AnyEvent::FastPing>
		873
		874	The fastest ping in the west.
		875
		876	=item L<AnyEvent::DBI>
		877
		878	Executes L<DBI> requests asynchronously in a proxy process.
		879
		880	=item L<AnyEvent::AIO>
		881
		882	Truly asynchronous I/O, should be in the toolbox of every event
		883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		884	together.
		885
		886	=item L<AnyEvent::BDB>
		887
		888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		889	L<BDB> and AnyEvent together.
		890
		891	=item L<AnyEvent::GPSD>
		892
		893	A non-blocking interface to gpsd, a daemon delivering GPS information.
		894
		895	=item L<AnyEvent::IGS>
		896
		897	A non-blocking interface to the Internet Go Server protocol (used by
		898	L<App::IGS>).
		899
		900	=item L<AnyEvent::IRC>
		901
		902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		903
		904	=item L<Net::XMPP2>
		905
		906	AnyEvent based XMPP (Jabber protocol) module family.
		907
		908	=item L<Net::FCP>
		909
		910	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		911	of AnyEvent.
		912
		913	=item L<Event::ExecFlow>
		914
		915	High level API for event-based execution flow control.
		916
		917	=item L<Coro>
		918
		919	Has special support for AnyEvent via L<Coro::AnyEvent>.
		920
		921	=item L<IO::Lambda>
		922
		923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		924
		925	=back
429		926
430	=cut	927	=cut
431		928
432	package AnyEvent;	929	package AnyEvent;
433		930
434	no warnings;	931	no warnings;
435	use strict;	932	use strict qw(vars subs);
436		933
437	use Carp;	934	use Carp;
438		935
439	our $VERSION = '3.3';	936	our $VERSION = 4.411;
440	our $MODEL;	937	our $MODEL;
441		938
442	our $AUTOLOAD;	939	our $AUTOLOAD;
443	our @ISA;	940	our @ISA;
444		941
		942	our @REGISTRY;
		943
		944	our $WIN32;
		945
		946	BEGIN {
		947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		949
		950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		951	if ${^TAINT};
		952	}
		953
445	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
446		955
447	our @REGISTRY;	956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		957
		958	{
		959	my $idx;
		960	$PROTOCOL{$_} = ++$idx
		961	for reverse split /\s*,\s*/,
		962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		963	}
448		964
449	my @models = (	965	my @models = (
450	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
452	[EV:: => AnyEvent::Impl::EV::],	966	[EV:: => AnyEvent::Impl::EV::],
453	[Event:: => AnyEvent::Impl::Event::],	967	[Event:: => AnyEvent::Impl::Event::],
454	[Glib:: => AnyEvent::Impl::Glib::],
455	[Tk:: => AnyEvent::Impl::Tk::],
456	[Wx:: => AnyEvent::Impl::POE::],
457	[Prima:: => AnyEvent::Impl::POE::],
458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
459	# everything below here will not be autoprobed as the pureperl backend should work everywhere	969	# everything below here will not be autoprobed
		970	# as the pureperl backend should work everywhere
		971	# and is usually faster
		972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		977	[Wx:: => AnyEvent::Impl::POE::],
		978	[Prima:: => AnyEvent::Impl::POE::],
463	);	979	);
464		980
465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	981	our %method = map +($_ => 1),
		982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		983
		984	our @post_detect;
		985
		986	sub post_detect(&) {
		987	my ($cb) = @_;
		988
		989	if ($MODEL) {
		990	$cb->();
		991
		992	1
		993	} else {
		994	push @post_detect, $cb;
		995
		996	defined wantarray
		997	? bless \$cb, "AnyEvent::Util::postdetect"
		998	: ()
		999	}
		1000	}
		1001
		1002	sub AnyEvent::Util::postdetect::DESTROY {
		1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1004	}
466		1005
467	sub detect() {	1006	sub detect() {
468	unless ($MODEL) {	1007	unless ($MODEL) {
469	no strict 'refs';	1008	no strict 'refs';
		1009	local $SIG{__DIE__};
470		1010
471	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
472	my $model = "AnyEvent::Impl::$1";	1012	my $model = "AnyEvent::Impl::$1";
473	if (eval "require $model") {	1013	if (eval "require $model") {
474	$MODEL = $model;	1014	$MODEL = $model;
…		…
504	last;	1044	last;
505	}	1045	}
506	}	1046	}
507		1047
508	$MODEL	1048	$MODEL
509	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
510	}	1050	}
511	}	1051	}
512		1052
		1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1054
513	unshift @ISA, $MODEL;	1055	unshift @ISA, $MODEL;
514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1056
		1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1058
		1059	(shift @post_detect)->() while @post_detect;
515	}	1060	}
516		1061
517	$MODEL	1062	$MODEL
518	}	1063	}
519		1064
…		…
527		1072
528	my $class = shift;	1073	my $class = shift;
529	$class->$func (@_);	1074	$class->$func (@_);
530	}	1075	}
531		1076
		1077	# utility function to dup a filehandle. this is used by many backends
		1078	# to support binding more than one watcher per filehandle (they usually
		1079	# allow only one watcher per fd, so we dup it to get a different one).
		1080	sub _dupfh($$$$) {
		1081	my ($poll, $fh, $r, $w) = @_;
		1082
		1083	# cygwin requires the fh mode to be matching, unix doesn't
		1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1085	: $poll eq "w" ? ($w, ">")
		1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1087
		1088	open my $fh2, "$mode&" . fileno $fh
		1089	or die "cannot dup() filehandle: $!,";
		1090
		1091	# we assume CLOEXEC is already set by perl in all important cases
		1092
		1093	($fh2, $rw)
		1094	}
		1095
532	package AnyEvent::Base;	1096	package AnyEvent::Base;
533		1097
		1098	# default implementations for many methods
		1099
		1100	BEGIN {
		1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1102	*_time = \&Time::HiRes::time;
		1103	# if (eval "use POSIX (); (POSIX::times())...
		1104	} else {
		1105	*_time = sub { time }; # epic fail
		1106	}
		1107	}
		1108
		1109	sub time { _time }
		1110	sub now { _time }
		1111	sub now_update { }
		1112
534	# default implementation for ->condvar, ->wait, ->broadcast	1113	# default implementation for ->condvar
535		1114
536	sub condvar {	1115	sub condvar {
537	bless \my $flag, "AnyEvent::Base::CondVar"	1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
538	}
539
540	sub AnyEvent::Base::CondVar::broadcast {
541	${$_[0]}++;
542	}
543
544	sub AnyEvent::Base::CondVar::wait {
545	AnyEvent->one_event while !${$_[0]};
546	}	1117	}
547		1118
548	# default implementation for ->signal	1119	# default implementation for ->signal
549		1120
550	our %SIG_CB;	1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1122
		1123	sub _signal_exec {
		1124	sysread $SIGPIPE_R, my $dummy, 4;
		1125
		1126	while (%SIG_EV) {
		1127	for (keys %SIG_EV) {
		1128	delete $SIG_EV{$_};
		1129	$_->() for values %{ $SIG_CB{$_} || {} };
		1130	}
		1131	}
		1132	}
551		1133
552	sub signal {	1134	sub signal {
553	my (undef, %arg) = @_;	1135	my (undef, %arg) = @_;
554		1136
		1137	unless ($SIGPIPE_R) {
		1138	require Fcntl;
		1139
		1140	if (AnyEvent::WIN32) {
		1141	require AnyEvent::Util;
		1142
		1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1146	} else {
		1147	pipe $SIGPIPE_R, $SIGPIPE_W;
		1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154	}
		1155
		1156	$SIGPIPE_R
		1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1158
		1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1160	}
		1161
555	my $signal = uc $arg{signal}	1162	my $signal = uc $arg{signal}
556	or Carp::croak "required option 'signal' is missing";	1163	or Carp::croak "required option 'signal' is missing";
557		1164
558	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
559	$SIG{$signal} ||= sub {	1166	$SIG{$signal} ||= sub {
560	$_->() for values %{ $SIG_CB{$signal} || {} };	1167	local $!;
		1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1169	undef $SIG_EV{$signal};
561	};	1170	};
562		1171
563	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
564	}	1173	}
565		1174
566	sub AnyEvent::Base::Signal::DESTROY {	1175	sub AnyEvent::Base::signal::DESTROY {
567	my ($signal, $cb) = @{$_[0]};	1176	my ($signal, $cb) = @{$_[0]};
568		1177
569	delete $SIG_CB{$signal}{$cb};	1178	delete $SIG_CB{$signal}{$cb};
570		1179
		1180	# delete doesn't work with older perls - they then
		1181	# print weird messages, or just unconditionally exit
		1182	# instead of getting the default action.
571	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
572	}	1184	}
573		1185
574	# default implementation for ->child	1186	# default implementation for ->child
575		1187
576	our %PID_CB;	1188	our %PID_CB;
577	our $CHLD_W;	1189	our $CHLD_W;
578	our $CHLD_DELAY_W;	1190	our $CHLD_DELAY_W;
579	our $PID_IDLE;
580	our $WNOHANG;	1191	our $WNOHANG;
581		1192
582	sub _child_wait {	1193	sub _sigchld {
583	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
584	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
585	(values %{ $PID_CB{0} || {} });	1196	(values %{ $PID_CB{0} || {} });
586	}	1197	}
587
588	undef $PID_IDLE;
589	}
590
591	sub _sigchld {
592	# make sure we deliver these changes "synchronous" with the event loop.
593	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
594	undef $CHLD_DELAY_W;
595	&_child_wait;
596	});
597	}	1198	}
598		1199
599	sub child {	1200	sub child {
600	my (undef, %arg) = @_;	1201	my (undef, %arg) = @_;
601		1202
602	defined (my $pid = $arg{pid} + 0)	1203	defined (my $pid = $arg{pid} + 0)
603	or Carp::croak "required option 'pid' is missing";	1204	or Carp::croak "required option 'pid' is missing";
604		1205
605	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
606		1207
607	unless ($WNOHANG) {
608	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
609	}
610		1209
611	unless ($CHLD_W) {	1210	unless ($CHLD_W) {
612	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
613	# child could be a zombie already, so make at least one round	1212	# child could be a zombie already, so make at least one round
614	&_sigchld;	1213	&_sigchld;
615	}	1214	}
616		1215
617	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
618	}	1217	}
619		1218
620	sub AnyEvent::Base::Child::DESTROY {	1219	sub AnyEvent::Base::child::DESTROY {
621	my ($pid, $cb) = @{$_[0]};	1220	my ($pid, $cb) = @{$_[0]};
622		1221
623	delete $PID_CB{$pid}{$cb};	1222	delete $PID_CB{$pid}{$cb};
624	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
625		1224
626	undef $CHLD_W unless keys %PID_CB;	1225	undef $CHLD_W unless keys %PID_CB;
627	}	1226	}
		1227
		1228	# idle emulation is done by simply using a timer, regardless
		1229	# of whether the process is idle or not, and not letting
		1230	# the callback use more than 50% of the time.
		1231	sub idle {
		1232	my (undef, %arg) = @_;
		1233
		1234	my ($cb, $w, $rcb) = $arg{cb};
		1235
		1236	$rcb = sub {
		1237	if ($cb) {
		1238	$w = _time;
		1239	&$cb;
		1240	$w = _time - $w;
		1241
		1242	# never use more then 50% of the time for the idle watcher,
		1243	# within some limits
		1244	$w = 0.0001 if $w < 0.0001;
		1245	$w = 5 if $w > 5;
		1246
		1247	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1248	} else {
		1249	# clean up...
		1250	undef $w;
		1251	undef $rcb;
		1252	}
		1253	};
		1254
		1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1256
		1257	bless \\$cb, "AnyEvent::Base::idle"
		1258	}
		1259
		1260	sub AnyEvent::Base::idle::DESTROY {
		1261	undef $${$_[0]};
		1262	}
		1263
		1264	package AnyEvent::CondVar;
		1265
		1266	our @ISA = AnyEvent::CondVar::Base::;
		1267
		1268	package AnyEvent::CondVar::Base;
		1269
		1270	use overload
		1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1272	fallback => 1;
		1273
		1274	sub _send {
		1275	# nop
		1276	}
		1277
		1278	sub send {
		1279	my $cv = shift;
		1280	$cv->{_ae_sent} = [@_];
		1281	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1282	$cv->_send;
		1283	}
		1284
		1285	sub croak {
		1286	$_[0]{_ae_croak} = $_[1];
		1287	$_[0]->send;
		1288	}
		1289
		1290	sub ready {
		1291	$_[0]{_ae_sent}
		1292	}
		1293
		1294	sub _wait {
		1295	AnyEvent->one_event while !$_[0]{_ae_sent};
		1296	}
		1297
		1298	sub recv {
		1299	$_[0]->_wait;
		1300
		1301	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1302	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1303	}
		1304
		1305	sub cb {
		1306	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1307	$_[0]{_ae_cb}
		1308	}
		1309
		1310	sub begin {
		1311	++$_[0]{_ae_counter};
		1312	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1313	}
		1314
		1315	sub end {
		1316	return if --$_[0]{_ae_counter};
		1317	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1318	}
		1319
		1320	# undocumented/compatibility with pre-3.4
		1321	*broadcast = \&send;
		1322	*wait = \&_wait;
		1323
		1324	=head1 ERROR AND EXCEPTION HANDLING
		1325
		1326	In general, AnyEvent does not do any error handling - it relies on the
		1327	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1328	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1329	checking of all AnyEvent methods, however, which is highly useful during
		1330	development.
		1331
		1332	As for exception handling (i.e. runtime errors and exceptions thrown while
		1333	executing a callback), this is not only highly event-loop specific, but
		1334	also not in any way wrapped by this module, as this is the job of the main
		1335	program.
		1336
		1337	The pure perl event loop simply re-throws the exception (usually
		1338	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1340	so on.
		1341
		1342	=head1 ENVIRONMENT VARIABLES
		1343
		1344	The following environment variables are used by this module or its
		1345	submodules.
		1346
		1347	Note that AnyEvent will remove I<all> environment variables starting with
		1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1349	enabled.
		1350
		1351	=over 4
		1352
		1353	=item C<PERL_ANYEVENT_VERBOSE>
		1354
		1355	By default, AnyEvent will be completely silent except in fatal
		1356	conditions. You can set this environment variable to make AnyEvent more
		1357	talkative.
		1358
		1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1360	conditions, such as not being able to load the event model specified by
		1361	C<PERL_ANYEVENT_MODEL>.
		1362
		1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1364	model it chooses.
		1365
		1366	=item C<PERL_ANYEVENT_STRICT>
		1367
		1368	AnyEvent does not do much argument checking by default, as thorough
		1369	argument checking is very costly. Setting this variable to a true value
		1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1371	check the arguments passed to most method calls. If it finds any problems
		1372	it will croak.
		1373
		1374	In other words, enables "strict" mode.
		1375
		1376	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1378	developing programs can be very useful, however.
		1379
		1380	=item C<PERL_ANYEVENT_MODEL>
		1381
		1382	This can be used to specify the event model to be used by AnyEvent, before
		1383	auto detection and -probing kicks in. It must be a string consisting
		1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1385	and the resulting module name is loaded and if the load was successful,
		1386	used as event model. If it fails to load AnyEvent will proceed with
		1387	auto detection and -probing.
		1388
		1389	This functionality might change in future versions.
		1390
		1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1392	could start your program like this:
		1393
		1394	PERL_ANYEVENT_MODEL=Perl perl ...
		1395
		1396	=item C<PERL_ANYEVENT_PROTOCOLS>
		1397
		1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1400	of auto probing).
		1401
		1402	Must be set to a comma-separated list of protocols or address families,
		1403	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1404	used, and preference will be given to protocols mentioned earlier in the
		1405	list.
		1406
		1407	This variable can effectively be used for denial-of-service attacks
		1408	against local programs (e.g. when setuid), although the impact is likely
		1409	small, as the program has to handle conenction and other failures anyways.
		1410
		1411	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1413	- only support IPv4, never try to resolve or contact IPv6
		1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1415	IPv6, but prefer IPv6 over IPv4.
		1416
		1417	=item C<PERL_ANYEVENT_EDNS0>
		1418
		1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1420	for DNS. This extension is generally useful to reduce DNS traffic, but
		1421	some (broken) firewalls drop such DNS packets, which is why it is off by
		1422	default.
		1423
		1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1425	EDNS0 in its DNS requests.
		1426
		1427	=item C<PERL_ANYEVENT_MAX_FORKS>
		1428
		1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1430	will create in parallel.
		1431
		1432	=back
628		1433
629	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
630		1435
631	This is an advanced topic that you do not normally need to use AnyEvent in	1436	This is an advanced topic that you do not normally need to use AnyEvent in
632	a module. This section is only of use to event loop authors who want to	1437	a module. This section is only of use to event loop authors who want to
…		…
667	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1472	I<rxvt-unicode> also cheats a bit by not providing blocking access to
668	condition variables: code blocking while waiting for a condition will	1473	condition variables: code blocking while waiting for a condition will
669	C<die>. This still works with most modules/usages, and blocking calls must	1474	C<die>. This still works with most modules/usages, and blocking calls must
670	not be done in an interactive application, so it makes sense.	1475	not be done in an interactive application, so it makes sense.
671		1476
672	=head1 ENVIRONMENT VARIABLES
673
674	The following environment variables are used by this module:
675
676	=over 4
677
678	=item C<PERL_ANYEVENT_VERBOSE>
679
680	By default, AnyEvent will be completely silent except in fatal
681	conditions. You can set this environment variable to make AnyEvent more
682	talkative.
683
684	When set to C<1> or higher, causes AnyEvent to warn about unexpected
685	conditions, such as not being able to load the event model specified by
686	C<PERL_ANYEVENT_MODEL>.
687
688	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
689	model it chooses.
690
691	=item C<PERL_ANYEVENT_MODEL>
692
693	This can be used to specify the event model to be used by AnyEvent, before
694	autodetection and -probing kicks in. It must be a string consisting
695	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
696	and the resulting module name is loaded and if the load was successful,
697	used as event model. If it fails to load AnyEvent will proceed with
698	autodetection and -probing.
699
700	This functionality might change in future versions.
701
702	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
703	could start your program like this:
704
705	PERL_ANYEVENT_MODEL=Perl perl ...
706
707	=back
708
709	=head1 EXAMPLE PROGRAM	1477	=head1 EXAMPLE PROGRAM
710		1478
711	The following program uses an IO watcher to read data from STDIN, a timer	1479	The following program uses an I/O watcher to read data from STDIN, a timer
712	to display a message once per second, and a condition variable to quit the	1480	to display a message once per second, and a condition variable to quit the
713	program when the user enters quit:	1481	program when the user enters quit:
714		1482
715	use AnyEvent;	1483	use AnyEvent;
716		1484
…		…
721	poll => 'r',	1489	poll => 'r',
722	cb => sub {	1490	cb => sub {
723	warn "io event <$_[0]>\n"; # will always output <r>	1491	warn "io event <$_[0]>\n"; # will always output <r>
724	chomp (my $input = <STDIN>); # read a line	1492	chomp (my $input = <STDIN>); # read a line
725	warn "read: $input\n"; # output what has been read	1493	warn "read: $input\n"; # output what has been read
726	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1494	$cv->send if $input =~ /^q/i; # quit program if /^q/i
727	},	1495	},
728	);	1496	);
729		1497
730	my $time_watcher; # can only be used once	1498	my $time_watcher; # can only be used once
731		1499
…		…
736	});	1504	});
737	}	1505	}
738		1506
739	new_timer; # create first timer	1507	new_timer; # create first timer
740		1508
741	$cv->wait; # wait until user enters /^q/i	1509	$cv->recv; # wait until user enters /^q/i
742		1510
743	=head1 REAL-WORLD EXAMPLE	1511	=head1 REAL-WORLD EXAMPLE
744		1512
745	Consider the L<Net::FCP> module. It features (among others) the following	1513	Consider the L<Net::FCP> module. It features (among others) the following
746	API calls, which are to freenet what HTTP GET requests are to http:	1514	API calls, which are to freenet what HTTP GET requests are to http:
…		…
796	syswrite $txn->{fh}, $txn->{request}	1564	syswrite $txn->{fh}, $txn->{request}
797	or die "connection or write error";	1565	or die "connection or write error";
798	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1566	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
799		1567
800	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1568	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
801	result and signals any possible waiters that the request ahs finished:	1569	result and signals any possible waiters that the request has finished:
802		1570
803	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1571	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
804		1572
805	if (end-of-file or data complete) {	1573	if (end-of-file or data complete) {
806	$txn->{result} = $txn->{buf};	1574	$txn->{result} = $txn->{buf};
807	$txn->{finished}->broadcast;	1575	$txn->{finished}->send;
808	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1576	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
809	}	1577	}
810		1578
811	The C<result> method, finally, just waits for the finished signal (if the	1579	The C<result> method, finally, just waits for the finished signal (if the
812	request was already finished, it doesn't wait, of course, and returns the	1580	request was already finished, it doesn't wait, of course, and returns the
813	data:	1581	data:
814		1582
815	$txn->{finished}->wait;	1583	$txn->{finished}->recv;
816	return $txn->{result};	1584	return $txn->{result};
817		1585
818	The actual code goes further and collects all errors (C<die>s, exceptions)	1586	The actual code goes further and collects all errors (C<die>s, exceptions)
819	that occured during request processing. The C<result> method detects	1587	that occurred during request processing. The C<result> method detects
820	whether an exception as thrown (it is stored inside the $txn object)	1588	whether an exception as thrown (it is stored inside the $txn object)
821	and just throws the exception, which means connection errors and other	1589	and just throws the exception, which means connection errors and other
822	problems get reported tot he code that tries to use the result, not in a	1590	problems get reported tot he code that tries to use the result, not in a
823	random callback.	1591	random callback.
824		1592
…		…
855		1623
856	my $quit = AnyEvent->condvar;	1624	my $quit = AnyEvent->condvar;
857		1625
858	$fcp->txn_client_get ($url)->cb (sub {	1626	$fcp->txn_client_get ($url)->cb (sub {
859	...	1627	...
860	$quit->broadcast;	1628	$quit->send;
861	});	1629	});
862		1630
863	$quit->wait;	1631	$quit->recv;
864		1632
865		1633
866	=head1 BENCHMARK	1634	=head1 BENCHMARKS
867		1635
868	To give you an idea of the performance and overheads that AnyEvent adds	1636	To give you an idea of the performance and overheads that AnyEvent adds
869	over the backends directly, here is a benchmark of various supported event	1637	over the event loops themselves and to give you an impression of the speed
870	models natively and with anyevent. The benchmark creates a lot of timers	1638	of various event loops I prepared some benchmarks.
		1639
		1640	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1641
		1642	Here is a benchmark of various supported event models used natively and
		1643	through AnyEvent. The benchmark creates a lot of timers (with a zero
871	(with a zero timeout) and io watchers (watching STDOUT, a pty, to become	1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
872	writable, which it is), lets them fire exactly once and destroys them	1645	which it is), lets them fire exactly once and destroys them again.
873	again.
874		1646
875	Explanation of the fields:	1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
		1648	distribution.
876		1649
		1650	=head3 Explanation of the columns
		1651
877	I<watcher> is the number of event watchers created/destroyed. Sicne	1652	I<watcher> is the number of event watchers created/destroyed. Since
878	different event models have vastly different performance each backend was	1653	different event models feature vastly different performances, each event
879	handed a number of watchers so that overall runtime is acceptable and	1654	loop was given a number of watchers so that overall runtime is acceptable
880	similar to all backends (and keep them from crashing).	1655	and similar between tested event loop (and keep them from crashing): Glib
		1656	would probably take thousands of years if asked to process the same number
		1657	of watchers as EV in this benchmark.
881		1658
882	I<bytes> is the number of bytes (as measured by resident set size) used by	1659	I<bytes> is the number of bytes (as measured by the resident set size,
883	each watcher.	1660	RSS) consumed by each watcher. This method of measuring captures both C
		1661	and Perl-based overheads.
884		1662
885	I<create> is the time, in microseconds, to create a single watcher.	1663	I<create> is the time, in microseconds (millionths of seconds), that it
		1664	takes to create a single watcher. The callback is a closure shared between
		1665	all watchers, to avoid adding memory overhead. That means closure creation
		1666	and memory usage is not included in the figures.
886		1667
887	I<invoke> is the time, in microseconds, used to invoke a simple callback	1668	I<invoke> is the time, in microseconds, used to invoke a simple
888	that simply counts down.	1669	callback. The callback simply counts down a Perl variable and after it was
		1670	invoked "watcher" times, it would C<< ->send >> a condvar once to
		1671	signal the end of this phase.
889		1672
890	I<destroy> is the time, in microseconds, to destroy a single watcher.	1673	I<destroy> is the time, in microseconds, that it takes to destroy a single
		1674	watcher.
891		1675
		1676	=head3 Results
		1677
892	name watcher bytes create invoke destroy comment	1678	name watchers bytes create invoke destroy comment
893	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
894	EV/Any 100000 610 3.52 0.91 0.75	1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
895	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal	1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
896	Perl/Any 10000 654 4.64 1.22 0.77 pure perl implementation	1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
897	Event/Event 10000 523 28.05 21.38 5.22 Event native interface	1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
898	Event/Any 10000 943 34.43 20.48 1.39	1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
899	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour	1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
900	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers	1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
901	POE/Select 2000 6343 94.69 807.65 562.69 POE::Loop::Select
902	POE/Event 2000 6644 108.15 768.19 14.33 POE::Loop::Event	1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
		1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
903		1689
904	Discussion: The benchmark does I<not> bench scalability of the	1690	=head3 Discussion
		1691
		1692	The benchmark does I<not> measure scalability of the event loop very
905	backend. For example a select-based backend (such as the pureperl one) can	1693	well. For example, a select-based event loop (such as the pure perl one)
906	never compete with a backend using epoll. In this benchmark, only a single	1694	can never compete with an event loop that uses epoll when the number of
907	filehandle is used.	1695	file descriptors grows high. In this benchmark, all events become ready at
		1696	the same time, so select/poll-based implementations get an unnatural speed
		1697	boost.
908		1698
		1699	Also, note that the number of watchers usually has a nonlinear effect on
		1700	overall speed, that is, creating twice as many watchers doesn't take twice
		1701	the time - usually it takes longer. This puts event loops tested with a
		1702	higher number of watchers at a disadvantage.
		1703
		1704	To put the range of results into perspective, consider that on the
		1705	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1706	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1707	cycles with POE.
		1708
909	EV is the sole leader regarding speed and memory use, which are both	1709	C<EV> is the sole leader regarding speed and memory use, which are both
910	maximal/minimal. Even when going through AnyEvent, there is only one event	1710	maximal/minimal, respectively. Even when going through AnyEvent, it uses
911	loop that uses less memory (the Event module natively), and no faster	1711	far less memory than any other event loop and is still faster than Event
912	event model.	1712	natively.
913		1713
914	The pure perl implementation is hit in a few sweet spots (both the	1714	The pure perl implementation is hit in a few sweet spots (both the
915	zero timeout and the use of a single fd hit optimisations in the perl	1715	constant timeout and the use of a single fd hit optimisations in the perl
916	interpreter and the backend itself), but it shows that it adds very little	1716	interpreter and the backend itself). Nevertheless this shows that it
917	overhead in itself. Like any select-based backend it's performance becomes	1717	adds very little overhead in itself. Like any select-based backend its
918	really bad with lots of file descriptors.	1718	performance becomes really bad with lots of file descriptors (and few of
		1719	them active), of course, but this was not subject of this benchmark.
919		1720
920	The Event module has a relatively high setup and callback invocation cost,	1721	The C<Event> module has a relatively high setup and callback invocation
921	but overall scores on the third place.	1722	cost, but overall scores in on the third place.
922		1723
923	Glib has a little higher memory cost, a bit fster callback invocation and	1724	C<Glib>'s memory usage is quite a bit higher, but it features a
924	has a similar speed as Event.	1725	faster callback invocation and overall ends up in the same class as
		1726	C<Event>. However, Glib scales extremely badly, doubling the number of
		1727	watchers increases the processing time by more than a factor of four,
		1728	making it completely unusable when using larger numbers of watchers
		1729	(note that only a single file descriptor was used in the benchmark, so
		1730	inefficiencies of C<poll> do not account for this).
925		1731
926	The Tk backend works relatively well, the fact that it crashes with	1732	The C<Tk> adaptor works relatively well. The fact that it crashes with
927	more than 2000 watchers is a big setback, however, as correctness takes	1733	more than 2000 watchers is a big setback, however, as correctness takes
928	precedence over speed.	1734	precedence over speed. Nevertheless, its performance is surprising, as the
		1735	file descriptor is dup()ed for each watcher. This shows that the dup()
		1736	employed by some adaptors is not a big performance issue (it does incur a
		1737	hidden memory cost inside the kernel which is not reflected in the figures
		1738	above).
929		1739
930	POE, regardless of backend (wether it's pure perl select backend or the	1740	C<POE>, regardless of underlying event loop (whether using its pure perl
931	Event backend) shows abysmal performance and memory usage: Watchers use	1741	select-based backend or the Event module, the POE-EV backend couldn't
932	almost 30 times as much memory as EV watchers, and 10 times as much memory	1742	be tested because it wasn't working) shows abysmal performance and
933	as both Event or EV via AnyEvent.	1743	memory usage with AnyEvent: Watchers use almost 30 times as much memory
		1744	as EV watchers, and 10 times as much memory as Event (the high memory
		1745	requirements are caused by requiring a session for each watcher). Watcher
		1746	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1747	implementation.
934		1748
		1749	The design of the POE adaptor class in AnyEvent can not really account
		1750	for the performance issues, though, as session creation overhead is
		1751	small compared to execution of the state machine, which is coded pretty
		1752	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1753	using multiple sessions is not a good approach, especially regarding
		1754	memory usage, even the author of POE could not come up with a faster
		1755	design).
		1756
		1757	=head3 Summary
		1758
		1759	=over 4
		1760
935	Summary: using EV through AnyEvent is faster than any other event	1761	=item * Using EV through AnyEvent is faster than any other event loop
936	loop. The overhead AnyEvent adds can be very small, and you should avoid	1762	(even when used without AnyEvent), but most event loops have acceptable
937	POE like the plague if you want performance or reasonable memory usage.	1763	performance with or without AnyEvent.
		1764
		1765	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
		1766	the actual event loop, only with extremely fast event loops such as EV
		1767	adds AnyEvent significant overhead.
		1768
		1769	=item * You should avoid POE like the plague if you want performance or
		1770	reasonable memory usage.
		1771
		1772	=back
		1773
		1774	=head2 BENCHMARKING THE LARGE SERVER CASE
		1775
		1776	This benchmark actually benchmarks the event loop itself. It works by
		1777	creating a number of "servers": each server consists of a socket pair, a
		1778	timeout watcher that gets reset on activity (but never fires), and an I/O
		1779	watcher waiting for input on one side of the socket. Each time the socket
		1780	watcher reads a byte it will write that byte to a random other "server".
		1781
		1782	The effect is that there will be a lot of I/O watchers, only part of which
		1783	are active at any one point (so there is a constant number of active
		1784	fds for each loop iteration, but which fds these are is random). The
		1785	timeout is reset each time something is read because that reflects how
		1786	most timeouts work (and puts extra pressure on the event loops).
		1787
		1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		1789	(1%) are active. This mirrors the activity of large servers with many
		1790	connections, most of which are idle at any one point in time.
		1791
		1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		1793	distribution.
		1794
		1795	=head3 Explanation of the columns
		1796
		1797	I<sockets> is the number of sockets, and twice the number of "servers" (as
		1798	each server has a read and write socket end).
		1799
		1800	I<create> is the time it takes to create a socket pair (which is
		1801	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		1802
		1803	I<request>, the most important value, is the time it takes to handle a
		1804	single "request", that is, reading the token from the pipe and forwarding
		1805	it to another server. This includes deleting the old timeout and creating
		1806	a new one that moves the timeout into the future.
		1807
		1808	=head3 Results
		1809
		1810	name sockets create request
		1811	EV 20000 69.01 11.16
		1812	Perl 20000 73.32 35.87
		1813	Event 20000 212.62 257.32
		1814	Glib 20000 651.16 1896.30
		1815	POE 20000 349.67 12317.24 uses POE::Loop::Event
		1816
		1817	=head3 Discussion
		1818
		1819	This benchmark I<does> measure scalability and overall performance of the
		1820	particular event loop.
		1821
		1822	EV is again fastest. Since it is using epoll on my system, the setup time
		1823	is relatively high, though.
		1824
		1825	Perl surprisingly comes second. It is much faster than the C-based event
		1826	loops Event and Glib.
		1827
		1828	Event suffers from high setup time as well (look at its code and you will
		1829	understand why). Callback invocation also has a high overhead compared to
		1830	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		1831	uses select or poll in basically all documented configurations.
		1832
		1833	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		1834	clearly fails to perform with many filehandles or in busy servers.
		1835
		1836	POE is still completely out of the picture, taking over 1000 times as long
		1837	as EV, and over 100 times as long as the Perl implementation, even though
		1838	it uses a C-based event loop in this case.
		1839
		1840	=head3 Summary
		1841
		1842	=over 4
		1843
		1844	=item * The pure perl implementation performs extremely well.
		1845
		1846	=item * Avoid Glib or POE in large projects where performance matters.
		1847
		1848	=back
		1849
		1850	=head2 BENCHMARKING SMALL SERVERS
		1851
		1852	While event loops should scale (and select-based ones do not...) even to
		1853	large servers, most programs we (or I :) actually write have only a few
		1854	I/O watchers.
		1855
		1856	In this benchmark, I use the same benchmark program as in the large server
		1857	case, but it uses only eight "servers", of which three are active at any
		1858	one time. This should reflect performance for a small server relatively
		1859	well.
		1860
		1861	The columns are identical to the previous table.
		1862
		1863	=head3 Results
		1864
		1865	name sockets create request
		1866	EV 16 20.00 6.54
		1867	Perl 16 25.75 12.62
		1868	Event 16 81.27 35.86
		1869	Glib 16 32.63 15.48
		1870	POE 16 261.87 276.28 uses POE::Loop::Event
		1871
		1872	=head3 Discussion
		1873
		1874	The benchmark tries to test the performance of a typical small
		1875	server. While knowing how various event loops perform is interesting, keep
		1876	in mind that their overhead in this case is usually not as important, due
		1877	to the small absolute number of watchers (that is, you need efficiency and
		1878	speed most when you have lots of watchers, not when you only have a few of
		1879	them).
		1880
		1881	EV is again fastest.
		1882
		1883	Perl again comes second. It is noticeably faster than the C-based event
		1884	loops Event and Glib, although the difference is too small to really
		1885	matter.
		1886
		1887	POE also performs much better in this case, but is is still far behind the
		1888	others.
		1889
		1890	=head3 Summary
		1891
		1892	=over 4
		1893
		1894	=item * C-based event loops perform very well with small number of
		1895	watchers, as the management overhead dominates.
		1896
		1897	=back
		1898
		1899	=head2 THE IO::Lambda BENCHMARK
		1900
		1901	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1904	shouldn't come as a surprise to anybody). As such, the benchmark is
		1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very
		1906	optimal. But how would AnyEvent compare when used without the extra
		1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1908
		1909	The benchmark itself creates an echo-server, and then, for 500 times,
		1910	connects to the echo server, sends a line, waits for the reply, and then
		1911	creates the next connection. This is a rather bad benchmark, as it doesn't
		1912	test the efficiency of the framework, but it is a benchmark nevertheless.
		1913
		1914	name runtime
		1915	Lambda/select 0.330 sec
		1916	+ optimized 0.122 sec
		1917	Lambda/AnyEvent 0.327 sec
		1918	+ optimized 0.138 sec
		1919	Raw sockets/select 0.077 sec
		1920	POE/select, components 0.662 sec
		1921	POE/select, raw sockets 0.226 sec
		1922	POE/select, optimized 0.404 sec
		1923
		1924	AnyEvent/select/nb 0.085 sec
		1925	AnyEvent/EV/nb 0.068 sec
		1926	+state machine 0.134 sec
		1927
		1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda
		1929	benchmarks actually make blocking connects and use 100% blocking I/O,
		1930	defeating the purpose of an event-based solution. All of the newly
		1931	written AnyEvent benchmarks use 100% non-blocking connects (using
		1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects
		1934	generally require a lot more bookkeeping and event handling than blocking
		1935	connects (which involve a single syscall only).
		1936
		1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1938	offers similar expressive power as POE and IO::Lambda (using conventional
		1939	Perl syntax), which means both the echo server and the client are 100%
		1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.
		1941
		1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets
		1943	benchmark", while AnyEvent + its pure perl backend easily beats
		1944	IO::Lambda and POE.
		1945
		1946	And even the 100% non-blocking version written using the high-level (and
		1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,
		1948	even thought it does all of DNS, tcp-connect and socket I/O in a
		1949	non-blocking way.
		1950
		1951
		1952	=head1 SIGNALS
		1953
		1954	AnyEvent currently installs handlers for these signals:
		1955
		1956	=over 4
		1957
		1958	=item SIGCHLD
		1959
		1960	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1961	emulation for event loops that do not support them natively. Also, some
		1962	event loops install a similar handler.
		1963
		1964	=item SIGPIPE
		1965
		1966	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1967	when AnyEvent gets loaded.
		1968
		1969	The rationale for this is that AnyEvent users usually do not really depend
		1970	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1971	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1972	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1973	some random socket.
		1974
		1975	The rationale for installing a no-op handler as opposed to ignoring it is
		1976	that this way, the handler will be restored to defaults on exec.
		1977
		1978	Feel free to install your own handler, or reset it to defaults.
		1979
		1980	=back
		1981
		1982	=cut
		1983
		1984	$SIG{PIPE} = sub { }
		1985	unless defined $SIG{PIPE};
938		1986
939		1987
940	=head1 FORK	1988	=head1 FORK
941		1989
942	Most event libraries are not fork-safe. The ones who are usually are	1990	Most event libraries are not fork-safe. The ones who are usually are
943	because they are so inefficient. Only L<EV> is fully fork-aware.	1991	because they rely on inefficient but fork-safe C<select> or C<poll>
		1992	calls. Only L<EV> is fully fork-aware.
944		1993
945	If you have to fork, you must either do so I<before> creating your first	1994	If you have to fork, you must either do so I<before> creating your first
946	watcher OR you must not use AnyEvent at all in the child.	1995	watcher OR you must not use AnyEvent at all in the child.
947		1996
948		1997
…		…
956	specified in the variable.	2005	specified in the variable.
957		2006
958	You can make AnyEvent completely ignore this variable by deleting it	2007	You can make AnyEvent completely ignore this variable by deleting it
959	before the first watcher gets created, e.g. with a C<BEGIN> block:	2008	before the first watcher gets created, e.g. with a C<BEGIN> block:
960		2009
961	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2010	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
962		2011
963	use AnyEvent;	2012	use AnyEvent;
		2013
		2014	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2015	be used to probe what backend is used and gain other information (which is
		2016	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2017	$ENV{PERL_ANYEVENT_STRICT}.
		2018
		2019
		2020	=head1 BUGS
		2021
		2022	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2023	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2024	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2025	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2026	pronounced).
964		2027
965		2028
966	=head1 SEE ALSO	2029	=head1 SEE ALSO
967		2030
968	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2031	Utility functions: L<AnyEvent::Util>.
969	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2032
		2033	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
970	L<Event::Lib>, L<Qt>, L<POE>.	2034	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
971		2035
972	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2036	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
973	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2037	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
974	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	2038	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
975	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2039	L<AnyEvent::Impl::POE>.
976		2040
		2041	Non-blocking file handles, sockets, TCP clients and
		2042	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		2043
		2044	Asynchronous DNS: L<AnyEvent::DNS>.
		2045
		2046	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		2047
977	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2048	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
978		2049
979		2050
980	=head1 AUTHOR	2051	=head1 AUTHOR
981		2052
982	Marc Lehmann <schmorp@schmorp.de>	2053	Marc Lehmann <schmorp@schmorp.de>
983	http://home.schmorp.de/	2054	http://home.schmorp.de/
984		2055
985	=cut	2056	=cut
986		2057
987	1	2058	1
988		2059

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