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Revision 1.132 by root, Sun May 25 01:05:27 2008 UTC vs.
Revision 1.238 by root, Thu Jul 16 03:48:33 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, 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
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		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 enormous 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		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	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
112	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
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	148	is in control).
119		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
120	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
121	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
122	to it).	158	to it).
123		159
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	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,
137	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
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	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
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (or a naked 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
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	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.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	203	handles.
162		204
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	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.
188		232
189	Example:	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.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# 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.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	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
215	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
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	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
235	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
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	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.
260		378
261	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
262	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
263	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
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	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.
		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).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
272	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
275		403
276	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
279		408
280	Example: fork a process and wait for it	409	Example: fork a process and wait for it
281		410
282	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
283		412
284	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
285		414
286	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
287	pid => $pid,	416	pid => $pid,
288	cb => sub {	417	cb => sub {
289	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
291	$done->send;	420	$done->send;
292	},	421	},
293	);	422	);
294		423
295	# do something else, then wait for process exit	424	# do something else, then wait for process exit
296	$done->recv;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
297		461
298	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
299		463
300	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
…		…
307	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	472	because they represent a condition that must become true.
309		473
310	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
312	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
314		480
315	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
317	were a callback).	483	were a callback, read about the caveats in the description for the C<<
		484	->send >> method).
318		485
319	Condition variables are similar to callbacks, except that you can	486	Condition variables are similar to callbacks, except that you can
320	optionally wait for them. They can also be called merge points - points	487	optionally wait for them. They can also be called merge points - points
321	in time where multiple outstanding events have been processed. And yet	488	in time where multiple outstanding events have been processed. And yet
322	another way to call them is transactions - each condition variable can be	489	another way to call them is transactions - each condition variable can be
…		…
373		540
374	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
375	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
376	$done->recv;	543	$done->recv;
377		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
378	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
379		563
380	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
381	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
382	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
394	immediately from within send.	578	immediately from within send.
395		579
396	Any arguments passed to the C<send> call will be returned by all	580	Any arguments passed to the C<send> call will be returned by all
397	future C<< ->recv >> calls.	581	future C<< ->recv >> calls.
398		582
399	Condition variables are overloaded so one can call them directly (as a	583	Condition variables are overloaded so one can call them directly
400	code reference). Calling them directly is the same as calling C<send>.	584	(as a code reference). Calling them directly is the same as calling
		585	C<send>. Note, however, that many C-based event loops do not handle
		586	overloading, so as tempting as it may be, passing a condition variable
		587	instead of a callback does not work. Both the pure perl and EV loops
		588	support overloading, however, as well as all functions that use perl to
		589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		590	example).
401		591
402	=item $cv->croak ($error)	592	=item $cv->croak ($error)
403		593
404	Similar to send, but causes all call's to C<< ->recv >> to invoke	594	Similar to send, but causes all call's to C<< ->recv >> to invoke
405	C<Carp::croak> with the given error message/object/scalar.	595	C<Carp::croak> with the given error message/object/scalar.
…		…
408	user/consumer.	598	user/consumer.
409		599
410	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
411		601
412	=item $cv->end	602	=item $cv->end
413
414	These two methods are EXPERIMENTAL and MIGHT CHANGE.
415		603
416	These two methods can be used to combine many transactions/events into	604	These two methods can be used to combine many transactions/events into
417	one. For example, a function that pings many hosts in parallel might want	605	one. For example, a function that pings many hosts in parallel might want
418	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
419		607
…		…
421	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
422	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
423	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
424	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
425		613
426	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
427		645
428	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
429		647
430	my %result;	648	my %result;
431	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
451	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
452	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
453	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
454	doesn't execute once).	672	doesn't execute once).
455		673
456	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
457	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
458	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
459	C<begin> and for each subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
460		679
461	=back	680	=back
462		681
463	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
464		683
…		…
509	=item $bool = $cv->ready	728	=item $bool = $cv->ready
510		729
511	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
512	C<croak> have been called.	731	C<croak> have been called.
513		732
514	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
515		734
516	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
517	replaces it before doing so.	736	replaces it before doing so.
518		737
519	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
520	C<send> or C<croak> are called. Calling C<recv> inside the callback	739	C<send> or C<croak> are called, with the only argument being the condition
521	or at any later time is guaranteed not to block.	740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
522		742
523	=back	743	=back
524		744
		745	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		746
		747	The available backend classes are (every class has its own manpage):
		748
		749	=over 4
		750
		751	=item Backends that are autoprobed when no other event loop can be found.
		752
		753	EV is the preferred backend when no other event loop seems to be in
		754	use. If EV is not installed, then AnyEvent will try Event, and, failing
		755	that, will fall back to its own pure-perl implementation, which is
		756	available everywhere as it comes with AnyEvent itself.
		757
		758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		761
		762	=item Backends that are transparently being picked up when they are used.
		763
		764	These will be used when they are currently loaded when the first watcher
		765	is created, in which case it is assumed that the application is using
		766	them. This means that AnyEvent will automatically pick the right backend
		767	when the main program loads an event module before anything starts to
		768	create watchers. Nothing special needs to be done by the main program.
		769
		770	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		771	AnyEvent::Impl::Tk based on Tk, very broken.
		772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		773	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		774
		775	=item Backends with special needs.
		776
		777	Qt requires the Qt::Application to be instantiated first, but will
		778	otherwise be picked up automatically. As long as the main program
		779	instantiates the application before any AnyEvent watchers are created,
		780	everything should just work.
		781
		782	AnyEvent::Impl::Qt based on Qt.
		783
		784	Support for IO::Async can only be partial, as it is too broken and
		785	architecturally limited to even support the AnyEvent API. It also
		786	is the only event loop that needs the loop to be set explicitly, so
		787	it can only be used by a main program knowing about AnyEvent. See
		788	L<AnyEvent::Impl::Async> for the gory details.
		789
		790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		791
		792	=item Event loops that are indirectly supported via other backends.
		793
		794	Some event loops can be supported via other modules:
		795
		796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		797
		798	B<WxWidgets> has no support for watching file handles. However, you can
		799	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		800	polls 20 times per second, which was considered to be too horrible to even
		801	consider for AnyEvent.
		802
		803	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		804	backend, so it can be supported through POE.
		805
		806	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		807	load L<POE> when detecting them, in the hope that POE will pick them up,
		808	in which case everything will be automatic.
		809
		810	=back
		811
525	=head1 GLOBAL VARIABLES AND FUNCTIONS	812	=head1 GLOBAL VARIABLES AND FUNCTIONS
526		813
		814	These are not normally required to use AnyEvent, but can be useful to
		815	write AnyEvent extension modules.
		816
527	=over 4	817	=over 4
528		818
529	=item $AnyEvent::MODEL	819	=item $AnyEvent::MODEL
530		820
531	Contains C<undef> until the first watcher is being created. Then it	821	Contains C<undef> until the first watcher is being created, before the
		822	backend has been autodetected.
		823
532	contains the event model that is being used, which is the name of the	824	Afterwards it contains the event model that is being used, which is the
533	Perl class implementing the model. This class is usually one of the	825	name of the Perl class implementing the model. This class is usually one
534	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	826	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
535	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	827	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
536		828	will be C<urxvt::anyevent>).
537	The known classes so far are:
538
539	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
540	AnyEvent::Impl::Event based on Event, second best choice.
541	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
542	AnyEvent::Impl::Glib based on Glib, third-best choice.
543	AnyEvent::Impl::Tk based on Tk, very bad choice.
544	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
545	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
546	AnyEvent::Impl::POE based on POE, not generic enough for full support.
547
548	There is no support for WxWidgets, as WxWidgets has no support for
549	watching file handles. However, you can use WxWidgets through the
550	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
551	second, which was considered to be too horrible to even consider for
552	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
553	it's adaptor.
554
555	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
556	autodetecting them.
557		829
558	=item AnyEvent::detect	830	=item AnyEvent::detect
559		831
560	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	832	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
561	if necessary. You should only call this function right before you would	833	if necessary. You should only call this function right before you would
562	have created an AnyEvent watcher anyway, that is, as late as possible at	834	have created an AnyEvent watcher anyway, that is, as late as possible at
563	runtime.	835	runtime, and not e.g. while initialising of your module.
		836
		837	If you need to do some initialisation before AnyEvent watchers are
		838	created, use C<post_detect>.
564		839
565	=item $guard = AnyEvent::post_detect { BLOCK }	840	=item $guard = AnyEvent::post_detect { BLOCK }
566		841
567	Arranges for the code block to be executed as soon as the event model is	842	Arranges for the code block to be executed as soon as the event model is
568	autodetected (or immediately if this has already happened).	843	autodetected (or immediately if this has already happened).
		844
		845	The block will be executed I<after> the actual backend has been detected
		846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		848	other initialisations - see the sources of L<AnyEvent::Strict> or
		849	L<AnyEvent::AIO> to see how this is used.
		850
		851	The most common usage is to create some global watchers, without forcing
		852	event module detection too early, for example, L<AnyEvent::AIO> creates
		853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		854	avoid autodetecting the event module at load time.
569		855
570	If called in scalar or list context, then it creates and returns an object	856	If called in scalar or list context, then it creates and returns an object
571	that automatically removes the callback again when it is destroyed. See	857	that automatically removes the callback again when it is destroyed. See
572	L<Coro::BDB> for a case where this is useful.	858	L<Coro::BDB> for a case where this is useful.
573		859
…		…
576	If there are any code references in this array (you can C<push> to it	862	If there are any code references in this array (you can C<push> to it
577	before or after loading AnyEvent), then they will called directly after	863	before or after loading AnyEvent), then they will called directly after
578	the event loop has been chosen.	864	the event loop has been chosen.
579		865
580	You should check C<$AnyEvent::MODEL> before adding to this array, though:	866	You should check C<$AnyEvent::MODEL> before adding to this array, though:
581	if it contains a true value then the event loop has already been detected,	867	if it is defined then the event loop has already been detected, and the
582	and the array will be ignored.	868	array will be ignored.
583		869
584	Best use C<AnyEvent::post_detect { BLOCK }> instead.	870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		871	it,as it takes care of these details.
		872
		873	This variable is mainly useful for modules that can do something useful
		874	when AnyEvent is used and thus want to know when it is initialised, but do
		875	not need to even load it by default. This array provides the means to hook
		876	into AnyEvent passively, without loading it.
585		877
586	=back	878	=back
587		879
588	=head1 WHAT TO DO IN A MODULE	880	=head1 WHAT TO DO IN A MODULE
589		881
…		…
612		904
613	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	905	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
614	do anything special (it does not need to be event-based) and let AnyEvent	906	do anything special (it does not need to be event-based) and let AnyEvent
615	decide which implementation to chose if some module relies on it.	907	decide which implementation to chose if some module relies on it.
616		908
617	If the main program relies on a specific event model. For example, in	909	If the main program relies on a specific event model - for example, in
618	Gtk2 programs you have to rely on the Glib module. You should load the	910	Gtk2 programs you have to rely on the Glib module - you should load the
619	event module before loading AnyEvent or any module that uses it: generally	911	event module before loading AnyEvent or any module that uses it: generally
620	speaking, you should load it as early as possible. The reason is that	912	speaking, you should load it as early as possible. The reason is that
621	modules might create watchers when they are loaded, and AnyEvent will	913	modules might create watchers when they are loaded, and AnyEvent will
622	decide on the event model to use as soon as it creates watchers, and it	914	decide on the event model to use as soon as it creates watchers, and it
623	might chose the wrong one unless you load the correct one yourself.	915	might chose the wrong one unless you load the correct one yourself.
624		916
625	You can chose to use a rather inefficient pure-perl implementation by	917	You can chose to use a pure-perl implementation by loading the
626	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	918	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
627	behaviour everywhere, but letting AnyEvent chose is generally better.	919	everywhere, but letting AnyEvent chose the model is generally better.
		920
		921	=head2 MAINLOOP EMULATION
		922
		923	Sometimes (often for short test scripts, or even standalone programs who
		924	only want to use AnyEvent), you do not want to run a specific event loop.
		925
		926	In that case, you can use a condition variable like this:
		927
		928	AnyEvent->condvar->recv;
		929
		930	This has the effect of entering the event loop and looping forever.
		931
		932	Note that usually your program has some exit condition, in which case
		933	it is better to use the "traditional" approach of storing a condition
		934	variable somewhere, waiting for it, and sending it when the program should
		935	exit cleanly.
		936
628		937
629	=head1 OTHER MODULES	938	=head1 OTHER MODULES
630		939
631	The following is a non-exhaustive list of additional modules that use	940	The following is a non-exhaustive list of additional modules that use
632	AnyEvent and can therefore be mixed easily with other AnyEvent modules	941	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
633	in the same program. Some of the modules come with AnyEvent, some are	942	modules and other event loops in the same program. Some of the modules
634	available via CPAN.	943	come with AnyEvent, most are available via CPAN.
635		944
636	=over 4	945	=over 4
637		946
638	=item L<AnyEvent::Util>	947	=item L<AnyEvent::Util>
639		948
640	Contains various utility functions that replace often-used but blocking	949	Contains various utility functions that replace often-used but blocking
641	functions such as C<inet_aton> by event-/callback-based versions.	950	functions such as C<inet_aton> by event-/callback-based versions.
642
643	=item L<AnyEvent::Handle>
644
645	Provide read and write buffers and manages watchers for reads and writes.
646		951
647	=item L<AnyEvent::Socket>	952	=item L<AnyEvent::Socket>
648		953
649	Provides various utility functions for (internet protocol) sockets,	954	Provides various utility functions for (internet protocol) sockets,
650	addresses and name resolution. Also functions to create non-blocking tcp	955	addresses and name resolution. Also functions to create non-blocking tcp
651	connections or tcp servers, with IPv6 and SRV record support and more.	956	connections or tcp servers, with IPv6 and SRV record support and more.
652		957
		958	=item L<AnyEvent::Handle>
		959
		960	Provide read and write buffers, manages watchers for reads and writes,
		961	supports raw and formatted I/O, I/O queued and fully transparent and
		962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		963
		964	=item L<AnyEvent::DNS>
		965
		966	Provides rich asynchronous DNS resolver capabilities.
		967
		968	=item L<AnyEvent::HTTP>
		969
		970	A simple-to-use HTTP library that is capable of making a lot of concurrent
		971	HTTP requests.
		972
653	=item L<AnyEvent::HTTPD>	973	=item L<AnyEvent::HTTPD>
654		974
655	Provides a simple web application server framework.	975	Provides a simple web application server framework.
656		976
657	=item L<AnyEvent::DNS>
658
659	Provides rich asynchronous DNS resolver capabilities.
660
661	=item L<AnyEvent::FastPing>	977	=item L<AnyEvent::FastPing>
662		978
663	The fastest ping in the west.	979	The fastest ping in the west.
664		980
		981	=item L<AnyEvent::DBI>
		982
		983	Executes L<DBI> requests asynchronously in a proxy process.
		984
		985	=item L<AnyEvent::AIO>
		986
		987	Truly asynchronous I/O, should be in the toolbox of every event
		988	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		989	together.
		990
		991	=item L<AnyEvent::BDB>
		992
		993	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		994	L<BDB> and AnyEvent together.
		995
		996	=item L<AnyEvent::GPSD>
		997
		998	A non-blocking interface to gpsd, a daemon delivering GPS information.
		999
665	=item L<Net::IRC3>	1000	=item L<AnyEvent::IRC>
666		1001
667	AnyEvent based IRC client module family.	1002	AnyEvent based IRC client module family (replacing the older Net::IRC3).
668		1003
669	=item L<Net::XMPP2>	1004	=item L<AnyEvent::XMPP>
670		1005
671	AnyEvent based XMPP (Jabber protocol) module family.	1006	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1007	Net::XMPP2>.
		1008
		1009	=item L<AnyEvent::IGS>
		1010
		1011	A non-blocking interface to the Internet Go Server protocol (used by
		1012	L<App::IGS>).
672		1013
673	=item L<Net::FCP>	1014	=item L<Net::FCP>
674		1015
675	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1016	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
676	of AnyEvent.	1017	of AnyEvent.
…		…
681		1022
682	=item L<Coro>	1023	=item L<Coro>
683		1024
684	Has special support for AnyEvent via L<Coro::AnyEvent>.	1025	Has special support for AnyEvent via L<Coro::AnyEvent>.
685		1026
686	=item L<AnyEvent::AIO>, L<IO::AIO>
687
688	Truly asynchronous I/O, should be in the toolbox of every event
689	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
690	together.
691
692	=item L<AnyEvent::BDB>, L<BDB>
693
694	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
695	IO::AIO and AnyEvent together.
696
697	=item L<IO::Lambda>
698
699	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
700
701	=back	1027	=back
702		1028
703	=cut	1029	=cut
704		1030
705	package AnyEvent;	1031	package AnyEvent;
706		1032
707	no warnings;	1033	no warnings;
708	use strict;	1034	use strict qw(vars subs);
709		1035
710	use Carp;	1036	use Carp;
711		1037
712	our $VERSION = '4.03';	1038	our $VERSION = 4.82;
713	our $MODEL;	1039	our $MODEL;
714		1040
715	our $AUTOLOAD;	1041	our $AUTOLOAD;
716	our @ISA;	1042	our @ISA;
717		1043
		1044	our @REGISTRY;
		1045
		1046	our $WIN32;
		1047
		1048	BEGIN {
		1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1051
		1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1053	if ${^TAINT};
		1054	}
		1055
718	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
719		1057
720	our @REGISTRY;	1058	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
721
722	our %PROTOCOL; # (ipv4|ipv6) => (1|2)
723		1059
724	{	1060	{
725	my $idx;	1061	my $idx;
726	$PROTOCOL{$_} = ++$idx	1062	$PROTOCOL{$_} = ++$idx
		1063	for reverse split /\s*,\s*/,
727	for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1064	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
728	}	1065	}
729		1066
730	my @models = (	1067	my @models = (
731	[EV:: => AnyEvent::Impl::EV::],	1068	[EV:: => AnyEvent::Impl::EV::],
732	[Event:: => AnyEvent::Impl::Event::],	1069	[Event:: => AnyEvent::Impl::Event::],
		1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1071	# everything below here will not be autoprobed
		1072	# as the pureperl backend should work everywhere
		1073	# and is usually faster
		1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
733	[Tk:: => AnyEvent::Impl::Tk::],	1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1077	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1078	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
734	[Wx:: => AnyEvent::Impl::POE::],	1079	[Wx:: => AnyEvent::Impl::POE::],
735	[Prima:: => AnyEvent::Impl::POE::],	1080	[Prima:: => AnyEvent::Impl::POE::],
736	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1081	# IO::Async is just too broken - we would need workarounds for its
737	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1082	# byzantine signal and broken child handling, among others.
738	[Glib:: => AnyEvent::Impl::Glib::],	1083	# IO::Async is rather hard to detect, as it doesn't have any
739	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1084	# obvious default class.
740	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1085	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
741	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1086	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1087	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
742	);	1088	);
743		1089
744	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1090	our %method = map +($_ => 1),
		1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
745		1092
746	our @post_detect;	1093	our @post_detect;
747		1094
748	sub post_detect(&) {	1095	sub post_detect(&) {
749	my ($cb) = @_;	1096	my ($cb) = @_;
…		…
754	1	1101	1
755	} else {	1102	} else {
756	push @post_detect, $cb;	1103	push @post_detect, $cb;
757		1104
758	defined wantarray	1105	defined wantarray
759	? bless \$cb, "AnyEvent::Util::PostDetect"	1106	? bless \$cb, "AnyEvent::Util::postdetect"
760	: ()	1107	: ()
761	}	1108	}
762	}	1109	}
763		1110
764	sub AnyEvent::Util::PostDetect::DESTROY {	1111	sub AnyEvent::Util::postdetect::DESTROY {
765	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
766	}	1113	}
767		1114
768	sub detect() {	1115	sub detect() {
769	unless ($MODEL) {	1116	unless ($MODEL) {
770	no strict 'refs';	1117	no strict 'refs';
		1118	local $SIG{__DIE__};
771		1119
772	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1120	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
773	my $model = "AnyEvent::Impl::$1";	1121	my $model = "AnyEvent::Impl::$1";
774	if (eval "require $model") {	1122	if (eval "require $model") {
775	$MODEL = $model;	1123	$MODEL = $model;
776	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1124	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1;
777	} else {	1125	} else {
778	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1126	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose;
779	}	1127	}
780	}	1128	}
781		1129
782	# check for already loaded models	1130	# check for already loaded models
783	unless ($MODEL) {	1131	unless ($MODEL) {
…		…
805	last;	1153	last;
806	}	1154	}
807	}	1155	}
808		1156
809	$MODEL	1157	$MODEL
810	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
811	}	1159	}
812	}	1160	}
813		1161
		1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1163
814	unshift @ISA, $MODEL;	1164	unshift @ISA, $MODEL;
815	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1165
		1166	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
816		1167
817	(shift @post_detect)->() while @post_detect;	1168	(shift @post_detect)->() while @post_detect;
818	}	1169	}
819		1170
820	$MODEL	1171	$MODEL
…		…
830		1181
831	my $class = shift;	1182	my $class = shift;
832	$class->$func (@_);	1183	$class->$func (@_);
833	}	1184	}
834		1185
		1186	# utility function to dup a filehandle. this is used by many backends
		1187	# to support binding more than one watcher per filehandle (they usually
		1188	# allow only one watcher per fd, so we dup it to get a different one).
		1189	sub _dupfh($$;$$) {
		1190	my ($poll, $fh, $r, $w) = @_;
		1191
		1192	# cygwin requires the fh mode to be matching, unix doesn't
		1193	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
		1194
		1195	open my $fh2, "$mode&", $fh
		1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1197
		1198	# we assume CLOEXEC is already set by perl in all important cases
		1199
		1200	($fh2, $rw)
		1201	}
		1202
835	package AnyEvent::Base;	1203	package AnyEvent::Base;
836		1204
		1205	# default implementations for many methods
		1206
		1207	BEGIN {
		1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1209	*_time = \&Time::HiRes::time;
		1210	# if (eval "use POSIX (); (POSIX::times())...
		1211	} else {
		1212	*_time = sub { time }; # epic fail
		1213	}
		1214	}
		1215
		1216	sub time { _time }
		1217	sub now { _time }
		1218	sub now_update { }
		1219
837	# default implementation for ->condvar	1220	# default implementation for ->condvar
838		1221
839	sub condvar {	1222	sub condvar {
840	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
841	}	1224	}
842		1225
843	# default implementation for ->signal	1226	# default implementation for ->signal
844		1227
845	our %SIG_CB;	1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1229
		1230	sub _signal_exec {
		1231	sysread $SIGPIPE_R, my $dummy, 4;
		1232
		1233	while (%SIG_EV) {
		1234	for (keys %SIG_EV) {
		1235	delete $SIG_EV{$_};
		1236	$_->() for values %{ $SIG_CB{$_} || {} };
		1237	}
		1238	}
		1239	}
846		1240
847	sub signal {	1241	sub signal {
848	my (undef, %arg) = @_;	1242	my (undef, %arg) = @_;
849		1243
		1244	unless ($SIGPIPE_R) {
		1245	require Fcntl;
		1246
		1247	if (AnyEvent::WIN32) {
		1248	require AnyEvent::Util;
		1249
		1250	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1251	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1252	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1253	} else {
		1254	pipe $SIGPIPE_R, $SIGPIPE_W;
		1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1257
		1258	# not strictly required, as $^F is normally 2, but let's make sure...
		1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1261	}
		1262
		1263	$SIGPIPE_R
		1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1265
		1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1267	}
		1268
850	my $signal = uc $arg{signal}	1269	my $signal = uc $arg{signal}
851	or Carp::croak "required option 'signal' is missing";	1270	or Carp::croak "required option 'signal' is missing";
852		1271
853	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
854	$SIG{$signal} ||= sub {	1273	$SIG{$signal} ||= sub {
855	$_->() for values %{ $SIG_CB{$signal} || {} };	1274	local $!;
		1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1276	undef $SIG_EV{$signal};
856	};	1277	};
857		1278
858	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
859	}	1280	}
860		1281
861	sub AnyEvent::Base::Signal::DESTROY {	1282	sub AnyEvent::Base::signal::DESTROY {
862	my ($signal, $cb) = @{$_[0]};	1283	my ($signal, $cb) = @{$_[0]};
863		1284
864	delete $SIG_CB{$signal}{$cb};	1285	delete $SIG_CB{$signal}{$cb};
865		1286
		1287	# delete doesn't work with older perls - they then
		1288	# print weird messages, or just unconditionally exit
		1289	# instead of getting the default action.
866	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1290	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
867	}	1291	}
868		1292
869	# default implementation for ->child	1293	# default implementation for ->child
870		1294
871	our %PID_CB;	1295	our %PID_CB;
872	our $CHLD_W;	1296	our $CHLD_W;
873	our $CHLD_DELAY_W;	1297	our $CHLD_DELAY_W;
874	our $PID_IDLE;
875	our $WNOHANG;	1298	our $WNOHANG;
876		1299
877	sub _child_wait {	1300	sub _sigchld {
878	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
879	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
880	(values %{ $PID_CB{0} || {} });	1303	(values %{ $PID_CB{0} || {} });
881	}	1304	}
882
883	undef $PID_IDLE;
884	}
885
886	sub _sigchld {
887	# make sure we deliver these changes "synchronous" with the event loop.
888	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
889	undef $CHLD_DELAY_W;
890	&_child_wait;
891	});
892	}	1305	}
893		1306
894	sub child {	1307	sub child {
895	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
896		1309
897	defined (my $pid = $arg{pid} + 0)	1310	defined (my $pid = $arg{pid} + 0)
898	or Carp::croak "required option 'pid' is missing";	1311	or Carp::croak "required option 'pid' is missing";
899		1312
900	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
901		1314
902	unless ($WNOHANG) {
903	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1315	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
904	}
905		1316
906	unless ($CHLD_W) {	1317	unless ($CHLD_W) {
907	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
908	# child could be a zombie already, so make at least one round	1319	# child could be a zombie already, so make at least one round
909	&_sigchld;	1320	&_sigchld;
910	}	1321	}
911		1322
912	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
913	}	1324	}
914		1325
915	sub AnyEvent::Base::Child::DESTROY {	1326	sub AnyEvent::Base::child::DESTROY {
916	my ($pid, $cb) = @{$_[0]};	1327	my ($pid, $cb) = @{$_[0]};
917		1328
918	delete $PID_CB{$pid}{$cb};	1329	delete $PID_CB{$pid}{$cb};
919	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
920		1331
921	undef $CHLD_W unless keys %PID_CB;	1332	undef $CHLD_W unless keys %PID_CB;
		1333	}
		1334
		1335	# idle emulation is done by simply using a timer, regardless
		1336	# of whether the process is idle or not, and not letting
		1337	# the callback use more than 50% of the time.
		1338	sub idle {
		1339	my (undef, %arg) = @_;
		1340
		1341	my ($cb, $w, $rcb) = $arg{cb};
		1342
		1343	$rcb = sub {
		1344	if ($cb) {
		1345	$w = _time;
		1346	&$cb;
		1347	$w = _time - $w;
		1348
		1349	# never use more then 50% of the time for the idle watcher,
		1350	# within some limits
		1351	$w = 0.0001 if $w < 0.0001;
		1352	$w = 5 if $w > 5;
		1353
		1354	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1355	} else {
		1356	# clean up...
		1357	undef $w;
		1358	undef $rcb;
		1359	}
		1360	};
		1361
		1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1363
		1364	bless \\$cb, "AnyEvent::Base::idle"
		1365	}
		1366
		1367	sub AnyEvent::Base::idle::DESTROY {
		1368	undef $${$_[0]};
922	}	1369	}
923		1370
924	package AnyEvent::CondVar;	1371	package AnyEvent::CondVar;
925		1372
926	our @ISA = AnyEvent::CondVar::Base::;	1373	our @ISA = AnyEvent::CondVar::Base::;
…		…
978	}	1425	}
979		1426
980	# undocumented/compatibility with pre-3.4	1427	# undocumented/compatibility with pre-3.4
981	*broadcast = \&send;	1428	*broadcast = \&send;
982	*wait = \&_wait;	1429	*wait = \&_wait;
		1430
		1431	=head1 ERROR AND EXCEPTION HANDLING
		1432
		1433	In general, AnyEvent does not do any error handling - it relies on the
		1434	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1435	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1436	checking of all AnyEvent methods, however, which is highly useful during
		1437	development.
		1438
		1439	As for exception handling (i.e. runtime errors and exceptions thrown while
		1440	executing a callback), this is not only highly event-loop specific, but
		1441	also not in any way wrapped by this module, as this is the job of the main
		1442	program.
		1443
		1444	The pure perl event loop simply re-throws the exception (usually
		1445	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1446	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1447	so on.
		1448
		1449	=head1 ENVIRONMENT VARIABLES
		1450
		1451	The following environment variables are used by this module or its
		1452	submodules.
		1453
		1454	Note that AnyEvent will remove I<all> environment variables starting with
		1455	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1456	enabled.
		1457
		1458	=over 4
		1459
		1460	=item C<PERL_ANYEVENT_VERBOSE>
		1461
		1462	By default, AnyEvent will be completely silent except in fatal
		1463	conditions. You can set this environment variable to make AnyEvent more
		1464	talkative.
		1465
		1466	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1467	conditions, such as not being able to load the event model specified by
		1468	C<PERL_ANYEVENT_MODEL>.
		1469
		1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1471	model it chooses.
		1472
		1473	=item C<PERL_ANYEVENT_STRICT>
		1474
		1475	AnyEvent does not do much argument checking by default, as thorough
		1476	argument checking is very costly. Setting this variable to a true value
		1477	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1478	check the arguments passed to most method calls. If it finds any problems,
		1479	it will croak.
		1480
		1481	In other words, enables "strict" mode.
		1482
		1483	Unlike C<use strict>, it is definitely recommended to keep it off in
		1484	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1485	developing programs can be very useful, however.
		1486
		1487	=item C<PERL_ANYEVENT_MODEL>
		1488
		1489	This can be used to specify the event model to be used by AnyEvent, before
		1490	auto detection and -probing kicks in. It must be a string consisting
		1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1492	and the resulting module name is loaded and if the load was successful,
		1493	used as event model. If it fails to load AnyEvent will proceed with
		1494	auto detection and -probing.
		1495
		1496	This functionality might change in future versions.
		1497
		1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1499	could start your program like this:
		1500
		1501	PERL_ANYEVENT_MODEL=Perl perl ...
		1502
		1503	=item C<PERL_ANYEVENT_PROTOCOLS>
		1504
		1505	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1506	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1507	of auto probing).
		1508
		1509	Must be set to a comma-separated list of protocols or address families,
		1510	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1511	used, and preference will be given to protocols mentioned earlier in the
		1512	list.
		1513
		1514	This variable can effectively be used for denial-of-service attacks
		1515	against local programs (e.g. when setuid), although the impact is likely
		1516	small, as the program has to handle conenction and other failures anyways.
		1517
		1518	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1519	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1520	- only support IPv4, never try to resolve or contact IPv6
		1521	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1522	IPv6, but prefer IPv6 over IPv4.
		1523
		1524	=item C<PERL_ANYEVENT_EDNS0>
		1525
		1526	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1527	for DNS. This extension is generally useful to reduce DNS traffic, but
		1528	some (broken) firewalls drop such DNS packets, which is why it is off by
		1529	default.
		1530
		1531	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1532	EDNS0 in its DNS requests.
		1533
		1534	=item C<PERL_ANYEVENT_MAX_FORKS>
		1535
		1536	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1537	will create in parallel.
		1538
		1539	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1540
		1541	The default value for the C<max_outstanding> parameter for the default DNS
		1542	resolver - this is the maximum number of parallel DNS requests that are
		1543	sent to the DNS server.
		1544
		1545	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1546
		1547	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1548	configuration) in the default resolver. When set to the empty string, no
		1549	default config will be used.
		1550
		1551	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1552
		1553	When neither C<ca_file> nor C<ca_path> was specified during
		1554	L<AnyEvent::TLS> context creation, and either of these environment
		1555	variables exist, they will be used to specify CA certificate locations
		1556	instead of a system-dependent default.
		1557
		1558	=back
983		1559
984	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
985		1561
986	This is an advanced topic that you do not normally need to use AnyEvent in	1562	This is an advanced topic that you do not normally need to use AnyEvent in
987	a module. This section is only of use to event loop authors who want to	1563	a module. This section is only of use to event loop authors who want to
…		…
1021		1597
1022	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1598	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1023	condition variables: code blocking while waiting for a condition will	1599	condition variables: code blocking while waiting for a condition will
1024	C<die>. This still works with most modules/usages, and blocking calls must	1600	C<die>. This still works with most modules/usages, and blocking calls must
1025	not be done in an interactive application, so it makes sense.	1601	not be done in an interactive application, so it makes sense.
1026
1027	=head1 ENVIRONMENT VARIABLES
1028
1029	The following environment variables are used by this module:
1030
1031	=over 4
1032
1033	=item C<PERL_ANYEVENT_VERBOSE>
1034
1035	By default, AnyEvent will be completely silent except in fatal
1036	conditions. You can set this environment variable to make AnyEvent more
1037	talkative.
1038
1039	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1040	conditions, such as not being able to load the event model specified by
1041	C<PERL_ANYEVENT_MODEL>.
1042
1043	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1044	model it chooses.
1045
1046	=item C<PERL_ANYEVENT_MODEL>
1047
1048	This can be used to specify the event model to be used by AnyEvent, before
1049	auto detection and -probing kicks in. It must be a string consisting
1050	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1051	and the resulting module name is loaded and if the load was successful,
1052	used as event model. If it fails to load AnyEvent will proceed with
1053	auto detection and -probing.
1054
1055	This functionality might change in future versions.
1056
1057	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1058	could start your program like this:
1059
1060	PERL_ANYEVENT_MODEL=Perl perl ...
1061
1062	=item C<PERL_ANYEVENT_PROTOCOLS>
1063
1064	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1065	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1066	of auto probing).
1067
1068	Must be set to a comma-separated list of protocols or address families,
1069	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1070	used, and preference will be given to protocols mentioned earlier in the
1071	list.
1072
1073	This variable can effectively be used for denial-of-service attacks
1074	against local programs (e.g. when setuid), although the impact is likely
1075	small, as the program has to handle connection errors already-
1076
1077	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1078	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1079	- only support IPv4, never try to resolve or contact IPv6
1080	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1081	IPv6, but prefer IPv6 over IPv4.
1082
1083	=item C<PERL_ANYEVENT_EDNS0>
1084
1085	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1086	for DNS. This extension is generally useful to reduce DNS traffic, but
1087	some (broken) firewalls drop such DNS packets, which is why it is off by
1088	default.
1089
1090	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1091	EDNS0 in its DNS requests.
1092
1093	=back
1094		1602
1095	=head1 EXAMPLE PROGRAM	1603	=head1 EXAMPLE PROGRAM
1096		1604
1097	The following program uses an I/O watcher to read data from STDIN, a timer	1605	The following program uses an I/O watcher to read data from STDIN, a timer
1098	to display a message once per second, and a condition variable to quit the	1606	to display a message once per second, and a condition variable to quit the
…		…
1292	watcher.	1800	watcher.
1293		1801
1294	=head3 Results	1802	=head3 Results
1295		1803
1296	name watchers bytes create invoke destroy comment	1804	name watchers bytes create invoke destroy comment
1297	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1805	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1298	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1806	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1299	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1807	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1300	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1808	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1301	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1809	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1302	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1810	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1811	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1812	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1303	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1813	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1304	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1814	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1305	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1815	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1306	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1816	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1307		1817
1308	=head3 Discussion	1818	=head3 Discussion
1309		1819
1310	The benchmark does I<not> measure scalability of the event loop very	1820	The benchmark does I<not> measure scalability of the event loop very
1311	well. For example, a select-based event loop (such as the pure perl one)	1821	well. For example, a select-based event loop (such as the pure perl one)
…		…
1336	performance becomes really bad with lots of file descriptors (and few of	1846	performance becomes really bad with lots of file descriptors (and few of
1337	them active), of course, but this was not subject of this benchmark.	1847	them active), of course, but this was not subject of this benchmark.
1338		1848
1339	The C<Event> module has a relatively high setup and callback invocation	1849	The C<Event> module has a relatively high setup and callback invocation
1340	cost, but overall scores in on the third place.	1850	cost, but overall scores in on the third place.
		1851
		1852	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1853	when using its pure perl backend.
1341		1854
1342	C<Glib>'s memory usage is quite a bit higher, but it features a	1855	C<Glib>'s memory usage is quite a bit higher, but it features a
1343	faster callback invocation and overall ends up in the same class as	1856	faster callback invocation and overall ends up in the same class as
1344	C<Event>. However, Glib scales extremely badly, doubling the number of	1857	C<Event>. However, Glib scales extremely badly, doubling the number of
1345	watchers increases the processing time by more than a factor of four,	1858	watchers increases the processing time by more than a factor of four,
…		…
1423	it to another server. This includes deleting the old timeout and creating	1936	it to another server. This includes deleting the old timeout and creating
1424	a new one that moves the timeout into the future.	1937	a new one that moves the timeout into the future.
1425		1938
1426	=head3 Results	1939	=head3 Results
1427		1940
1428	name sockets create request	1941	name sockets create request
1429	EV 20000 69.01 11.16	1942	EV 20000 69.01 11.16
1430	Perl 20000 73.32 35.87	1943	Perl 20000 73.32 35.87
		1944	IOAsync 20000 157.00 98.14 epoll
		1945	IOAsync 20000 159.31 616.06 poll
1431	Event 20000 212.62 257.32	1946	Event 20000 212.62 257.32
1432	Glib 20000 651.16 1896.30	1947	Glib 20000 651.16 1896.30
1433	POE 20000 349.67 12317.24 uses POE::Loop::Event	1948	POE 20000 349.67 12317.24 uses POE::Loop::Event
1434		1949
1435	=head3 Discussion	1950	=head3 Discussion
1436		1951
1437	This benchmark I<does> measure scalability and overall performance of the	1952	This benchmark I<does> measure scalability and overall performance of the
1438	particular event loop.	1953	particular event loop.
…		…
1440	EV is again fastest. Since it is using epoll on my system, the setup time	1955	EV is again fastest. Since it is using epoll on my system, the setup time
1441	is relatively high, though.	1956	is relatively high, though.
1442		1957
1443	Perl surprisingly comes second. It is much faster than the C-based event	1958	Perl surprisingly comes second. It is much faster than the C-based event
1444	loops Event and Glib.	1959	loops Event and Glib.
		1960
		1961	IO::Async performs very well when using its epoll backend, and still quite
		1962	good compared to Glib when using its pure perl backend.
1445		1963
1446	Event suffers from high setup time as well (look at its code and you will	1964	Event suffers from high setup time as well (look at its code and you will
1447	understand why). Callback invocation also has a high overhead compared to	1965	understand why). Callback invocation also has a high overhead compared to
1448	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1966	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1449	uses select or poll in basically all documented configurations.	1967	uses select or poll in basically all documented configurations.
…		…
1512	=item * C-based event loops perform very well with small number of	2030	=item * C-based event loops perform very well with small number of
1513	watchers, as the management overhead dominates.	2031	watchers, as the management overhead dominates.
1514		2032
1515	=back	2033	=back
1516		2034
		2035	=head2 THE IO::Lambda BENCHMARK
		2036
		2037	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2038	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2039	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2040	shouldn't come as a surprise to anybody). As such, the benchmark is
		2041	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2042	very optimal. But how would AnyEvent compare when used without the extra
		2043	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2044
		2045	The benchmark itself creates an echo-server, and then, for 500 times,
		2046	connects to the echo server, sends a line, waits for the reply, and then
		2047	creates the next connection. This is a rather bad benchmark, as it doesn't
		2048	test the efficiency of the framework or much non-blocking I/O, but it is a
		2049	benchmark nevertheless.
		2050
		2051	name runtime
		2052	Lambda/select 0.330 sec
		2053	+ optimized 0.122 sec
		2054	Lambda/AnyEvent 0.327 sec
		2055	+ optimized 0.138 sec
		2056	Raw sockets/select 0.077 sec
		2057	POE/select, components 0.662 sec
		2058	POE/select, raw sockets 0.226 sec
		2059	POE/select, optimized 0.404 sec
		2060
		2061	AnyEvent/select/nb 0.085 sec
		2062	AnyEvent/EV/nb 0.068 sec
		2063	+state machine 0.134 sec
		2064
		2065	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2066	benchmarks actually make blocking connects and use 100% blocking I/O,
		2067	defeating the purpose of an event-based solution. All of the newly
		2068	written AnyEvent benchmarks use 100% non-blocking connects (using
		2069	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2070	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2071	generally require a lot more bookkeeping and event handling than blocking
		2072	connects (which involve a single syscall only).
		2073
		2074	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2075	offers similar expressive power as POE and IO::Lambda, using conventional
		2076	Perl syntax. This means that both the echo server and the client are 100%
		2077	non-blocking, further placing it at a disadvantage.
		2078
		2079	As you can see, the AnyEvent + EV combination even beats the
		2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2081	backend easily beats IO::Lambda and POE.
		2082
		2083	And even the 100% non-blocking version written using the high-level (and
		2084	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2085	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2086	in a non-blocking way.
		2087
		2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2089	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2090	part of the IO::lambda distribution and were used without any changes.
		2091
		2092
		2093	=head1 SIGNALS
		2094
		2095	AnyEvent currently installs handlers for these signals:
		2096
		2097	=over 4
		2098
		2099	=item SIGCHLD
		2100
		2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2102	emulation for event loops that do not support them natively. Also, some
		2103	event loops install a similar handler.
		2104
		2105	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2106	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2107
		2108	=item SIGPIPE
		2109
		2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2111	when AnyEvent gets loaded.
		2112
		2113	The rationale for this is that AnyEvent users usually do not really depend
		2114	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2115	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2116	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2117	some random socket.
		2118
		2119	The rationale for installing a no-op handler as opposed to ignoring it is
		2120	that this way, the handler will be restored to defaults on exec.
		2121
		2122	Feel free to install your own handler, or reset it to defaults.
		2123
		2124	=back
		2125
		2126	=cut
		2127
		2128	undef $SIG{CHLD}
		2129	if $SIG{CHLD} eq 'IGNORE';
		2130
		2131	$SIG{PIPE} = sub { }
		2132	unless defined $SIG{PIPE};
1517		2133
1518	=head1 FORK	2134	=head1 FORK
1519		2135
1520	Most event libraries are not fork-safe. The ones who are usually are	2136	Most event libraries are not fork-safe. The ones who are usually are
1521	because they rely on inefficient but fork-safe C<select> or C<poll>	2137	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1535	specified in the variable.	2151	specified in the variable.
1536		2152
1537	You can make AnyEvent completely ignore this variable by deleting it	2153	You can make AnyEvent completely ignore this variable by deleting it
1538	before the first watcher gets created, e.g. with a C<BEGIN> block:	2154	before the first watcher gets created, e.g. with a C<BEGIN> block:
1539		2155
1540	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2156	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1541		2157
1542	use AnyEvent;	2158	use AnyEvent;
1543		2159
1544	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2160	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1545	be used to probe what backend is used and gain other information (which is	2161	be used to probe what backend is used and gain other information (which is
1546	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2162	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2163	$ENV{PERL_ANYEVENT_STRICT}.
		2164
		2165	Note that AnyEvent will remove I<all> environment variables starting with
		2166	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2167	enabled.
		2168
		2169
		2170	=head1 BUGS
		2171
		2172	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2173	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2174	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2175	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2176	pronounced).
1547		2177
1548		2178
1549	=head1 SEE ALSO	2179	=head1 SEE ALSO
1550		2180
1551	Utility functions: L<AnyEvent::Util>.	2181	Utility functions: L<AnyEvent::Util>.
…		…
1554	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2184	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1555		2185
1556	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1557	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1558	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1559	L<AnyEvent::Impl::POE>.	2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1560		2190
1561	Non-blocking file handles, sockets, TCP clients and	2191	Non-blocking file handles, sockets, TCP clients and
1562	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1563		2193
1564	Asynchronous DNS: L<AnyEvent::DNS>.	2194	Asynchronous DNS: L<AnyEvent::DNS>.
1565		2195
1566	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2197	L<Coro::Event>,
1567		2198
1568	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2200	L<AnyEvent::HTTP>.
1569		2201
1570		2202
1571	=head1 AUTHOR	2203	=head1 AUTHOR
1572		2204
1573	Marc Lehmann <schmorp@schmorp.de>	2205	Marc Lehmann <schmorp@schmorp.de>
1574	http://home.schmorp.de/	2206	http://home.schmorp.de/
1575		2207
1576	=cut	2208	=cut
1577		2209
1578	1	2210	1
1579		2211

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