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Revision 1.132 by root, Sun May 25 01:05:27 2008 UTC vs.
Revision 1.262 by root, Tue Jul 28 13:08:17 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# 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.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		53
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		55
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
27		58
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
30		61
31	First and foremost, I<AnyEvent is not an event model> itself, it only	62	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	63	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,	64	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,	65	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	66	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
37		69
38	The goal of AnyEvent is to offer module authors the ability to do event	70	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	71	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	72	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	73	module users into the same thing by forcing them to use the same event
42	model you use.	74	model you use.
43		75
44	For modules like POE or IO::Async (which is a total misnomer as it is	76	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	77	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	78	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	79	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	80	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.	81	module are I<also> forced to use the same event loop you use.
50		82
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	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	85	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,	86	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	87	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	88	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	89	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).	90	to AnyEvent, too, so it is future-proof).
59		91
60	In addition to being free of having to use I<the one and only true event	92	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	93	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	94	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	95	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	96	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	97	technically possible.
66		98
		99	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		100	of useful functionality, such as an asynchronous DNS resolver, 100%
		101	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		102	such as Windows) and lots of real-world knowledge and workarounds for
		103	platform bugs and differences.
		104
67	Of course, if you want lots of policy (this can arguably be somewhat	105	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	106	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	107	model, you should I<not> use this module.
70		108
71	=head1 DESCRIPTION	109	=head1 DESCRIPTION
72		110
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	140	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...	141	use AnyEvent so their modules work together with others seamlessly...
104		142
105	The pure-perl implementation of AnyEvent is called	143	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	144	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	145	explicitly and enjoy the high availability of that event loop :)
108		146
109	=head1 WATCHERS	147	=head1 WATCHERS
110		148
111	AnyEvent has the central concept of a I<watcher>, which is an object that	149	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	150	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	153	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	154	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	155	callback when the event occurs (of course, only when the event model
118	is in control).	156	is in control).
119		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
120	To disable the watcher you have to destroy it (e.g. by setting the	164	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	165	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	166	to it).
123		167
124	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	171	example), or need to refer to their watcher object in other ways.
128		172
129	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
130		174
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
133	undef $w;	177	undef $w;
134	});	178	});
135		179
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	180	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	181	my variables are only visible after the statement in which they are
138	declared.	182	declared.
139		183
140	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
141		185
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
144		188
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
146	for events. C<poll> must be a string that is either C<r> or C<w>,	196	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,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
148	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		200
151	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
154		204
…		…
158		208
159	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	210	always use non-blocking calls when reading/writing from/to your file
161	handles.	211	handles.
162		212
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	213	Example: wait for readability of STDIN, then read a line and disable the
		214	watcher.
		215
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	218	warn "read: $input\n";
169	undef $w;	219	undef $w;
170	});	220	});
…		…
180		230
181	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
184		234
185	The timer callback will be invoked at most once: if you want a repeating	235	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	236	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
188		240
189	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
190		244
191	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	248	warn "timeout\n";
194	});	249	});
195		250
196	# to cancel the timer:	251	# to cancel the timer:
197	undef $w;	252	undef $w;
198		253
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	254	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		255
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
207	};	258	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		259
212	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
213		261
214	There are two ways to handle timers: based on real time (relative, "fire	262	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	263	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	275	timers.
228		276
229	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	278	AnyEvent API.
231		279
		280	AnyEvent has two additional methods that return the "current time":
		281
		282	=over 4
		283
		284	=item AnyEvent->time
		285
		286	This returns the "current wallclock time" as a fractional number of
		287	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		288	return, and the result is guaranteed to be compatible with those).
		289
		290	It progresses independently of any event loop processing, i.e. each call
		291	will check the system clock, which usually gets updated frequently.
		292
		293	=item AnyEvent->now
		294
		295	This also returns the "current wallclock time", but unlike C<time>, above,
		296	this value might change only once per event loop iteration, depending on
		297	the event loop (most return the same time as C<time>, above). This is the
		298	time that AnyEvent's timers get scheduled against.
		299
		300	I<In almost all cases (in all cases if you don't care), this is the
		301	function to call when you want to know the current time.>
		302
		303	This function is also often faster then C<< AnyEvent->time >>, and
		304	thus the preferred method if you want some timestamp (for example,
		305	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		306
		307	The rest of this section is only of relevance if you try to be very exact
		308	with your timing, you can skip it without bad conscience.
		309
		310	For a practical example of when these times differ, consider L<Event::Lib>
		311	and L<EV> and the following set-up:
		312
		313	The event loop is running and has just invoked one of your callback at
		314	time=500 (assume no other callbacks delay processing). In your callback,
		315	you wait a second by executing C<sleep 1> (blocking the process for a
		316	second) and then (at time=501) you create a relative timer that fires
		317	after three seconds.
		318
		319	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		320	both return C<501>, because that is the current time, and the timer will
		321	be scheduled to fire at time=504 (C<501> + C<3>).
		322
		323	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		324	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		325	last event processing phase started. With L<EV>, your timer gets scheduled
		326	to run at time=503 (C<500> + C<3>).
		327
		328	In one sense, L<Event::Lib> is more exact, as it uses the current time
		329	regardless of any delays introduced by event processing. However, most
		330	callbacks do not expect large delays in processing, so this causes a
		331	higher drift (and a lot more system calls to get the current time).
		332
		333	In another sense, L<EV> is more exact, as your timer will be scheduled at
		334	the same time, regardless of how long event processing actually took.
		335
		336	In either case, if you care (and in most cases, you don't), then you
		337	can get whatever behaviour you want with any event loop, by taking the
		338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		339	account.
		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
		356	=back
		357
232	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
233		359
234	You can watch for signals using a signal watcher, C<signal> is the signal	360	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	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
237		363
238	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
241		367
…		…
243	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
245	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
246		372
247	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
249		376
250	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
252		380
253	Example: exit on SIGINT	381	Example: exit on SIGINT
254		382
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
257	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
258		402
259	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
260		404
261	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (one some backends,
262	watches for any child process exit). The watcher will trigger as often	406	using C<0> watches for any child process exit, on others this will
263	as status change for the child are received. This works by installing a	407	croak). The watcher will be triggered only when the child process has
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	finished and an exit status is available, not on any trace events
265	and exit status (as returned by waitpid), so unlike other watcher types,	409	(stopped/continued).
266	you I<can> rely on child watcher callback arguments.	410
		411	The callback will be called with the pid and exit status (as returned by
		412	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		413	callback arguments.
		414
		415	This watcher type works by installing a signal handler for C<SIGCHLD>,
		416	and since it cannot be shared, nothing else should use SIGCHLD or reap
		417	random child processes (waiting for specific child processes, e.g. inside
		418	C<system>, is just fine).
267		419
268	There is a slight catch to child watchers, however: you usually start them	420	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	421	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	422	have exited already (and no SIGCHLD will be sent anymore).
271		423
272	Not all event models handle this correctly (POE doesn't), but even for	424	Not all event models handle this correctly (neither POE nor IO::Async do,
		425	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	426	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).	427	the process exits (i.e. before you fork in the first place). AnyEvent's
		428	pure perl event loop handles all cases correctly regardless of when you
		429	start the watcher.
275		430
276	This means you cannot create a child watcher as the very first thing in an	431	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	432	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>).	433	watcher before you C<fork> the child (alternatively, you can call
		434	C<AnyEvent::detect>).
		435
		436	As most event loops do not support waiting for child events, they will be
		437	emulated by AnyEvent in most cases, in which the latency and race problems
		438	mentioned in the description of signal watchers apply.
279		439
280	Example: fork a process and wait for it	440	Example: fork a process and wait for it
281		441
282	my $done = AnyEvent->condvar;	442	my $done = AnyEvent->condvar;
283		443
284	my $pid = fork or exit 5;	444	my $pid = fork or exit 5;
285		445
286	my $w = AnyEvent->child (	446	my $w = AnyEvent->child (
287	pid => $pid,	447	pid => $pid,
288	cb => sub {	448	cb => sub {
289	my ($pid, $status) = @_;	449	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	450	warn "pid $pid exited with status $status";
291	$done->send;	451	$done->send;
292	},	452	},
293	);	453	);
294		454
295	# do something else, then wait for process exit	455	# do something else, then wait for process exit
296	$done->recv;	456	$done->recv;
		457
		458	=head2 IDLE WATCHERS
		459
		460	Sometimes there is a need to do something, but it is not so important
		461	to do it instantly, but only when there is nothing better to do. This
		462	"nothing better to do" is usually defined to be "no other events need
		463	attention by the event loop".
		464
		465	Idle watchers ideally get invoked when the event loop has nothing
		466	better to do, just before it would block the process to wait for new
		467	events. Instead of blocking, the idle watcher is invoked.
		468
		469	Most event loops unfortunately do not really support idle watchers (only
		470	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		471	will simply call the callback "from time to time".
		472
		473	Example: read lines from STDIN, but only process them when the
		474	program is otherwise idle:
		475
		476	my @lines; # read data
		477	my $idle_w;
		478	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		479	push @lines, scalar <STDIN>;
		480
		481	# start an idle watcher, if not already done
		482	$idle_w ||= AnyEvent->idle (cb => sub {
		483	# handle only one line, when there are lines left
		484	if (my $line = shift @lines) {
		485	print "handled when idle: $line";
		486	} else {
		487	# otherwise disable the idle watcher again
		488	undef $idle_w;
		489	}
		490	});
		491	});
297		492
298	=head2 CONDITION VARIABLES	493	=head2 CONDITION VARIABLES
299		494
300	If you are familiar with some event loops you will know that all of them	495	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	496	require you to run some blocking "loop", "run" or similar function that
302	will actively watch for new events and call your callbacks.	497	will actively watch for new events and call your callbacks.
303		498
304	AnyEvent is different, it expects somebody else to run the event loop and	499	AnyEvent is slightly different: it expects somebody else to run the event
305	will only block when necessary (usually when told by the user).	500	loop and will only block when necessary (usually when told by the user).
306		501
307	The instrument to do that is called a "condition variable", so called	502	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	503	because they represent a condition that must become true.
		504
		505	Now is probably a good time to look at the examples further below.
309		506
310	Condition variables can be created by calling the C<< AnyEvent->condvar	507	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	508	>> method, usually without arguments. The only argument pair allowed is
312	C<cb>, which specifies a callback to be called when the condition variable	509	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	510	becomes true, with the condition variable as the first argument (but not
		511	the results).
314		512
315	After creation, the condition variable is "false" until it becomes "true"	513	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	514	by calling the C<send> method (or calling the condition variable as if it
317	were a callback).	515	were a callback, read about the caveats in the description for the C<<
		516	->send >> method).
318		517
319	Condition variables are similar to callbacks, except that you can	518	Condition variables are similar to callbacks, except that you can
320	optionally wait for them. They can also be called merge points - points	519	optionally wait for them. They can also be called merge points - points
321	in time where multiple outstanding events have been processed. And yet	520	in time where multiple outstanding events have been processed. And yet
322	another way to call them is transactions - each condition variable can be	521	another way to call them is transactions - each condition variable can be
323	used to represent a transaction, which finishes at some point and delivers	522	used to represent a transaction, which finishes at some point and delivers
324	a result.	523	a result. And yet some people know them as "futures" - a promise to
		524	compute/deliver something that you can wait for.
325		525
326	Condition variables are very useful to signal that something has finished,	526	Condition variables are very useful to signal that something has finished,
327	for example, if you write a module that does asynchronous http requests,	527	for example, if you write a module that does asynchronous http requests,
328	then a condition variable would be the ideal candidate to signal the	528	then a condition variable would be the ideal candidate to signal the
329	availability of results. The user can either act when the callback is	529	availability of results. The user can either act when the callback is
…		…
363	after => 1,	563	after => 1,
364	cb => sub { $result_ready->send },	564	cb => sub { $result_ready->send },
365	);	565	);
366		566
367	# this "blocks" (while handling events) till the callback	567	# this "blocks" (while handling events) till the callback
368	# calls send	568	# calls -<send
369	$result_ready->recv;	569	$result_ready->recv;
370		570
371	Example: wait for a timer, but take advantage of the fact that	571	Example: wait for a timer, but take advantage of the fact that condition
372	condition variables are also code references.	572	variables are also callable directly.
373		573
374	my $done = AnyEvent->condvar;	574	my $done = AnyEvent->condvar;
375	my $delay = AnyEvent->timer (after => 5, cb => $done);	575	my $delay = AnyEvent->timer (after => 5, cb => $done);
376	$done->recv;	576	$done->recv;
		577
		578	Example: Imagine an API that returns a condvar and doesn't support
		579	callbacks. This is how you make a synchronous call, for example from
		580	the main program:
		581
		582	use AnyEvent::CouchDB;
		583
		584	...
		585
		586	my @info = $couchdb->info->recv;
		587
		588	And this is how you would just set a callback to be called whenever the
		589	results are available:
		590
		591	$couchdb->info->cb (sub {
		592	my @info = $_[0]->recv;
		593	});
377		594
378	=head3 METHODS FOR PRODUCERS	595	=head3 METHODS FOR PRODUCERS
379		596
380	These methods should only be used by the producing side, i.e. the	597	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	598	code/module that eventually sends the signal. Note that it is also
…		…
394	immediately from within send.	611	immediately from within send.
395		612
396	Any arguments passed to the C<send> call will be returned by all	613	Any arguments passed to the C<send> call will be returned by all
397	future C<< ->recv >> calls.	614	future C<< ->recv >> calls.
398		615
399	Condition variables are overloaded so one can call them directly (as a	616	Condition variables are overloaded so one can call them directly (as if
400	code reference). Calling them directly is the same as calling C<send>.	617	they were a code reference). Calling them directly is the same as calling
		618	C<send>.
401		619
402	=item $cv->croak ($error)	620	=item $cv->croak ($error)
403		621
404	Similar to send, but causes all call's to C<< ->recv >> to invoke	622	Similar to send, but causes all call's to C<< ->recv >> to invoke
405	C<Carp::croak> with the given error message/object/scalar.	623	C<Carp::croak> with the given error message/object/scalar.
406		624
407	This can be used to signal any errors to the condition variable	625	This can be used to signal any errors to the condition variable
408	user/consumer.	626	user/consumer. Doing it this way instead of calling C<croak> directly
		627	delays the error detetcion, but has the overwhelmign advantage that it
		628	diagnoses the error at the place where the result is expected, and not
		629	deep in some event clalback without connection to the actual code causing
		630	the problem.
409		631
410	=item $cv->begin ([group callback])	632	=item $cv->begin ([group callback])
411		633
412	=item $cv->end	634	=item $cv->end
413
414	These two methods are EXPERIMENTAL and MIGHT CHANGE.
415		635
416	These two methods can be used to combine many transactions/events into	636	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	637	one. For example, a function that pings many hosts in parallel might want
418	to use a condition variable for the whole process.	638	to use a condition variable for the whole process.
419		639
…		…
421	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	641	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	642	>>, 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	643	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.	644	callback was set, C<send> will be called without any arguments.
425		645
426	Let's clarify this with the ping example:	646	You can think of C<< $cv->send >> giving you an OR condition (one call
		647	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		648	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		649
		650	Let's start with a simple example: you have two I/O watchers (for example,
		651	STDOUT and STDERR for a program), and you want to wait for both streams to
		652	close before activating a condvar:
		653
		654	my $cv = AnyEvent->condvar;
		655
		656	$cv->begin; # first watcher
		657	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		658	defined sysread $fh1, my $buf, 4096
		659	or $cv->end;
		660	});
		661
		662	$cv->begin; # second watcher
		663	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		664	defined sysread $fh2, my $buf, 4096
		665	or $cv->end;
		666	});
		667
		668	$cv->recv;
		669
		670	This works because for every event source (EOF on file handle), there is
		671	one call to C<begin>, so the condvar waits for all calls to C<end> before
		672	sending.
		673
		674	The ping example mentioned above is slightly more complicated, as the
		675	there are results to be passwd back, and the number of tasks that are
		676	begung can potentially be zero:
427		677
428	my $cv = AnyEvent->condvar;	678	my $cv = AnyEvent->condvar;
429		679
430	my %result;	680	my %result;
431	$cv->begin (sub { $cv->send (\%result) });	681	$cv->begin (sub { $cv->send (\%result) });
…		…
451	loop, which serves two important purposes: first, it sets the callback	701	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	702	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	703	C<send> is called even when C<no> hosts are being pinged (the loop
454	doesn't execute once).	704	doesn't execute once).
455		705
456	This is the general pattern when you "fan out" into multiple subrequests:	706	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>	707	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	708	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>.	709	subrequest you start, call C<begin> and for each subrequest you finish,
		710	call C<end>.
460		711
461	=back	712	=back
462		713
463	=head3 METHODS FOR CONSUMERS	714	=head3 METHODS FOR CONSUMERS
464		715
…		…
480	function will call C<croak>.	731	function will call C<croak>.
481		732
482	In list context, all parameters passed to C<send> will be returned,	733	In list context, all parameters passed to C<send> will be returned,
483	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
484		735
		736	Note that doing a blocking wait in a callback is not supported by any
		737	event loop, that is, recursive invocation of a blocking C<< ->recv
		738	>> is not allowed, and the C<recv> call will C<croak> if such a
		739	condition is detected. This condition can be slightly loosened by using
		740	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		741	any thread that doesn't run the event loop itself.
		742
485	Not all event models support a blocking wait - some die in that case	743	Not all event models support a blocking wait - some die in that case
486	(programs might want to do that to stay interactive), so I<if you are	744	(programs might want to do that to stay interactive), so I<if you are
487	using this from a module, never require a blocking wait>, but let the	745	using this from a module, never require a blocking wait>. Instead, let the
488	caller decide whether the call will block or not (for example, by coupling	746	caller decide whether the call will block or not (for example, by coupling
489	condition variables with some kind of request results and supporting	747	condition variables with some kind of request results and supporting
490	callbacks so the caller knows that getting the result will not block,	748	callbacks so the caller knows that getting the result will not block,
491	while still supporting blocking waits if the caller so desires).	749	while still supporting blocking waits if the caller so desires).
492		750
493	Another reason I<never> to C<< ->recv >> in a module is that you cannot
494	sensibly have two C<< ->recv >>'s in parallel, as that would require
495	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
496	can supply.
497
498	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
499	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
500	versions and also integrates coroutines into AnyEvent, making blocking
501	C<< ->recv >> calls perfectly safe as long as they are done from another
502	coroutine (one that doesn't run the event loop).
503
504	You can ensure that C<< -recv >> never blocks by setting a callback and	751	You can ensure that C<< -recv >> never blocks by setting a callback and
505	only calling C<< ->recv >> from within that callback (or at a later	752	only calling C<< ->recv >> from within that callback (or at a later
506	time). This will work even when the event loop does not support blocking	753	time). This will work even when the event loop does not support blocking
507	waits otherwise.	754	waits otherwise.
508		755
509	=item $bool = $cv->ready	756	=item $bool = $cv->ready
510		757
511	Returns true when the condition is "true", i.e. whether C<send> or	758	Returns true when the condition is "true", i.e. whether C<send> or
512	C<croak> have been called.	759	C<croak> have been called.
513		760
514	=item $cb = $cv->cb ([new callback])	761	=item $cb = $cv->cb ($cb->($cv))
515		762
516	This is a mutator function that returns the callback set and optionally	763	This is a mutator function that returns the callback set and optionally
517	replaces it before doing so.	764	replaces it before doing so.
518		765
519	The callback will be called when the condition becomes "true", i.e. when	766	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	767	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.	768	variable itself. Calling C<recv> inside the callback or at any later time
		769	is guaranteed not to block.
522		770
523	=back	771	=back
524		772
		773	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		774
		775	The available backend classes are (every class has its own manpage):
		776
		777	=over 4
		778
		779	=item Backends that are autoprobed when no other event loop can be found.
		780
		781	EV is the preferred backend when no other event loop seems to be in
		782	use. If EV is not installed, then AnyEvent will try Event, and, failing
		783	that, will fall back to its own pure-perl implementation, which is
		784	available everywhere as it comes with AnyEvent itself.
		785
		786	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		787	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		788	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		789
		790	=item Backends that are transparently being picked up when they are used.
		791
		792	These will be used when they are currently loaded when the first watcher
		793	is created, in which case it is assumed that the application is using
		794	them. This means that AnyEvent will automatically pick the right backend
		795	when the main program loads an event module before anything starts to
		796	create watchers. Nothing special needs to be done by the main program.
		797
		798	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		799	AnyEvent::Impl::Tk based on Tk, very broken.
		800	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		801	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		802	AnyEvent::Impl::Irssi used when running within irssi.
		803
		804	=item Backends with special needs.
		805
		806	Qt requires the Qt::Application to be instantiated first, but will
		807	otherwise be picked up automatically. As long as the main program
		808	instantiates the application before any AnyEvent watchers are created,
		809	everything should just work.
		810
		811	AnyEvent::Impl::Qt based on Qt.
		812
		813	Support for IO::Async can only be partial, as it is too broken and
		814	architecturally limited to even support the AnyEvent API. It also
		815	is the only event loop that needs the loop to be set explicitly, so
		816	it can only be used by a main program knowing about AnyEvent. See
		817	L<AnyEvent::Impl::Async> for the gory details.
		818
		819	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		820
		821	=item Event loops that are indirectly supported via other backends.
		822
		823	Some event loops can be supported via other modules:
		824
		825	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		826
		827	B<WxWidgets> has no support for watching file handles. However, you can
		828	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		829	polls 20 times per second, which was considered to be too horrible to even
		830	consider for AnyEvent.
		831
		832	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		833	backend, so it can be supported through POE.
		834
		835	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		836	load L<POE> when detecting them, in the hope that POE will pick them up,
		837	in which case everything will be automatic.
		838
		839	=back
		840
525	=head1 GLOBAL VARIABLES AND FUNCTIONS	841	=head1 GLOBAL VARIABLES AND FUNCTIONS
526		842
		843	These are not normally required to use AnyEvent, but can be useful to
		844	write AnyEvent extension modules.
		845
527	=over 4	846	=over 4
528		847
529	=item $AnyEvent::MODEL	848	=item $AnyEvent::MODEL
530		849
531	Contains C<undef> until the first watcher is being created. Then it	850	Contains C<undef> until the first watcher is being created, before the
		851	backend has been autodetected.
		852
532	contains the event model that is being used, which is the name of the	853	Afterwards it contains the event model that is being used, which is the
533	Perl class implementing the model. This class is usually one of the	854	name of the Perl class implementing the model. This class is usually one
534	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	855	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
535	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	856	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
536		857	will be C<urxvt::anyevent>).
537	The known classes so far are:
538
539	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
540	AnyEvent::Impl::Event based on Event, second best choice.
541	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
542	AnyEvent::Impl::Glib based on Glib, third-best choice.
543	AnyEvent::Impl::Tk based on Tk, very bad choice.
544	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
545	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
546	AnyEvent::Impl::POE based on POE, not generic enough for full support.
547
548	There is no support for WxWidgets, as WxWidgets has no support for
549	watching file handles. However, you can use WxWidgets through the
550	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
551	second, which was considered to be too horrible to even consider for
552	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
553	it's adaptor.
554
555	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
556	autodetecting them.
557		858
558	=item AnyEvent::detect	859	=item AnyEvent::detect
559		860
560	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	861	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
561	if necessary. You should only call this function right before you would	862	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	863	have created an AnyEvent watcher anyway, that is, as late as possible at
563	runtime.	864	runtime, and not e.g. while initialising of your module.
		865
		866	If you need to do some initialisation before AnyEvent watchers are
		867	created, use C<post_detect>.
564		868
565	=item $guard = AnyEvent::post_detect { BLOCK }	869	=item $guard = AnyEvent::post_detect { BLOCK }
566		870
567	Arranges for the code block to be executed as soon as the event model is	871	Arranges for the code block to be executed as soon as the event model is
568	autodetected (or immediately if this has already happened).	872	autodetected (or immediately if this has already happened).
569		873
		874	The block will be executed I<after> the actual backend has been detected
		875	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		876	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		877	other initialisations - see the sources of L<AnyEvent::Strict> or
		878	L<AnyEvent::AIO> to see how this is used.
		879
		880	The most common usage is to create some global watchers, without forcing
		881	event module detection too early, for example, L<AnyEvent::AIO> creates
		882	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		883	avoid autodetecting the event module at load time.
		884
570	If called in scalar or list context, then it creates and returns an object	885	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	886	that automatically removes the callback again when it is destroyed (or
		887	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
572	L<Coro::BDB> for a case where this is useful.	888	a case where this is useful.
		889
		890	Example: Create a watcher for the IO::AIO module and store it in
		891	C<$WATCHER>. Only do so after the event loop is initialised, though.
		892
		893	our WATCHER;
		894
		895	my $guard = AnyEvent::post_detect {
		896	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		897	};
		898
		899	# the ||= is important in case post_detect immediately runs the block,
		900	# as to not clobber the newly-created watcher. assigning both watcher and
		901	# post_detect guard to the same variable has the advantage of users being
		902	# able to just C<undef $WATCHER> if the watcher causes them grief.
		903
		904	$WATCHER ||= $guard;
573		905
574	=item @AnyEvent::post_detect	906	=item @AnyEvent::post_detect
575		907
576	If there are any code references in this array (you can C<push> to it	908	If there are any code references in this array (you can C<push> to it
577	before or after loading AnyEvent), then they will called directly after	909	before or after loading AnyEvent), then they will called directly after
578	the event loop has been chosen.	910	the event loop has been chosen.
579		911
580	You should check C<$AnyEvent::MODEL> before adding to this array, though:	912	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,	913	if it is defined then the event loop has already been detected, and the
582	and the array will be ignored.	914	array will be ignored.
583		915
584	Best use C<AnyEvent::post_detect { BLOCK }> instead.	916	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		917	it,as it takes care of these details.
		918
		919	This variable is mainly useful for modules that can do something useful
		920	when AnyEvent is used and thus want to know when it is initialised, but do
		921	not need to even load it by default. This array provides the means to hook
		922	into AnyEvent passively, without loading it.
585		923
586	=back	924	=back
587		925
588	=head1 WHAT TO DO IN A MODULE	926	=head1 WHAT TO DO IN A MODULE
589		927
…		…
612		950
613	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	951	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	952	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.	953	decide which implementation to chose if some module relies on it.
616		954
617	If the main program relies on a specific event model. For example, in	955	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	956	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	957	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	958	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	959	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	960	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.	961	might chose the wrong one unless you load the correct one yourself.
624		962
625	You can chose to use a rather inefficient pure-perl implementation by	963	You can chose to use a pure-perl implementation by loading the
626	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	964	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
627	behaviour everywhere, but letting AnyEvent chose is generally better.	965	everywhere, but letting AnyEvent chose the model is generally better.
		966
		967	=head2 MAINLOOP EMULATION
		968
		969	Sometimes (often for short test scripts, or even standalone programs who
		970	only want to use AnyEvent), you do not want to run a specific event loop.
		971
		972	In that case, you can use a condition variable like this:
		973
		974	AnyEvent->condvar->recv;
		975
		976	This has the effect of entering the event loop and looping forever.
		977
		978	Note that usually your program has some exit condition, in which case
		979	it is better to use the "traditional" approach of storing a condition
		980	variable somewhere, waiting for it, and sending it when the program should
		981	exit cleanly.
		982
628		983
629	=head1 OTHER MODULES	984	=head1 OTHER MODULES
630		985
631	The following is a non-exhaustive list of additional modules that use	986	The following is a non-exhaustive list of additional modules that use
632	AnyEvent and can therefore be mixed easily with other AnyEvent modules	987	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	988	modules and other event loops in the same program. Some of the modules
634	available via CPAN.	989	come with AnyEvent, most are available via CPAN.
635		990
636	=over 4	991	=over 4
637		992
638	=item L<AnyEvent::Util>	993	=item L<AnyEvent::Util>
639		994
640	Contains various utility functions that replace often-used but blocking	995	Contains various utility functions that replace often-used but blocking
641	functions such as C<inet_aton> by event-/callback-based versions.	996	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		997
647	=item L<AnyEvent::Socket>	998	=item L<AnyEvent::Socket>
648		999
649	Provides various utility functions for (internet protocol) sockets,	1000	Provides various utility functions for (internet protocol) sockets,
650	addresses and name resolution. Also functions to create non-blocking tcp	1001	addresses and name resolution. Also functions to create non-blocking tcp
651	connections or tcp servers, with IPv6 and SRV record support and more.	1002	connections or tcp servers, with IPv6 and SRV record support and more.
652		1003
		1004	=item L<AnyEvent::Handle>
		1005
		1006	Provide read and write buffers, manages watchers for reads and writes,
		1007	supports raw and formatted I/O, I/O queued and fully transparent and
		1008	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1009
		1010	=item L<AnyEvent::DNS>
		1011
		1012	Provides rich asynchronous DNS resolver capabilities.
		1013
		1014	=item L<AnyEvent::HTTP>
		1015
		1016	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1017	HTTP requests.
		1018
653	=item L<AnyEvent::HTTPD>	1019	=item L<AnyEvent::HTTPD>
654		1020
655	Provides a simple web application server framework.	1021	Provides a simple web application server framework.
656		1022
657	=item L<AnyEvent::DNS>
658
659	Provides rich asynchronous DNS resolver capabilities.
660
661	=item L<AnyEvent::FastPing>	1023	=item L<AnyEvent::FastPing>
662		1024
663	The fastest ping in the west.	1025	The fastest ping in the west.
664		1026
		1027	=item L<AnyEvent::DBI>
		1028
		1029	Executes L<DBI> requests asynchronously in a proxy process.
		1030
		1031	=item L<AnyEvent::AIO>
		1032
		1033	Truly asynchronous I/O, should be in the toolbox of every event
		1034	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1035	together.
		1036
		1037	=item L<AnyEvent::BDB>
		1038
		1039	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1040	L<BDB> and AnyEvent together.
		1041
		1042	=item L<AnyEvent::GPSD>
		1043
		1044	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1045
665	=item L<Net::IRC3>	1046	=item L<AnyEvent::IRC>
666		1047
667	AnyEvent based IRC client module family.	1048	AnyEvent based IRC client module family (replacing the older Net::IRC3).
668		1049
669	=item L<Net::XMPP2>	1050	=item L<AnyEvent::XMPP>
670		1051
671	AnyEvent based XMPP (Jabber protocol) module family.	1052	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1053	Net::XMPP2>.
		1054
		1055	=item L<AnyEvent::IGS>
		1056
		1057	A non-blocking interface to the Internet Go Server protocol (used by
		1058	L<App::IGS>).
672		1059
673	=item L<Net::FCP>	1060	=item L<Net::FCP>
674		1061
675	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1062	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
676	of AnyEvent.	1063	of AnyEvent.
…		…
681		1068
682	=item L<Coro>	1069	=item L<Coro>
683		1070
684	Has special support for AnyEvent via L<Coro::AnyEvent>.	1071	Has special support for AnyEvent via L<Coro::AnyEvent>.
685		1072
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	1073	=back
702		1074
703	=cut	1075	=cut
704		1076
705	package AnyEvent;	1077	package AnyEvent;
706		1078
		1079	# basically a tuned-down version of common::sense
		1080	sub common_sense {
707	no warnings;	1081	# no warnings
708	use strict;	1082	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1083	# use strict vars subs
		1084	$^H |= 0x00000600;
		1085	}
709		1086
		1087	BEGIN { AnyEvent::common_sense }
		1088
710	use Carp;	1089	use Carp ();
711		1090
712	our $VERSION = '4.03';	1091	our $VERSION = 4.881;
713	our $MODEL;	1092	our $MODEL;
714		1093
715	our $AUTOLOAD;	1094	our $AUTOLOAD;
716	our @ISA;	1095	our @ISA;
717		1096
718	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
719
720	our @REGISTRY;	1097	our @REGISTRY;
721		1098
722	our %PROTOCOL; # (ipv4|ipv6) => (1|2)	1099	our $WIN32;
		1100
		1101	our $VERBOSE;
		1102
		1103	BEGIN {
		1104	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1105	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1106
		1107	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1108	if ${^TAINT};
		1109
		1110	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1111
		1112	}
		1113
		1114	our $MAX_SIGNAL_LATENCY = 10;
		1115
		1116	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
723		1117
724	{	1118	{
725	my $idx;	1119	my $idx;
726	$PROTOCOL{$_} = ++$idx	1120	$PROTOCOL{$_} = ++$idx
		1121	for reverse split /\s*,\s*/,
727	for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1122	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
728	}	1123	}
729		1124
730	my @models = (	1125	my @models = (
731	[EV:: => AnyEvent::Impl::EV::],	1126	[EV:: => AnyEvent::Impl::EV:: , 1],
732	[Event:: => AnyEvent::Impl::Event::],	1127	[Event:: => AnyEvent::Impl::Event::, 1],
		1128	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
		1129	# everything below here will not (normally) be autoprobed
		1130	# as the pureperl backend should work everywhere
		1131	# and is usually faster
		1132	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1133	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1134	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
733	[Tk:: => AnyEvent::Impl::Tk::],	1135	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1136	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1137	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
734	[Wx:: => AnyEvent::Impl::POE::],	1138	[Wx:: => AnyEvent::Impl::POE::],
735	[Prima:: => AnyEvent::Impl::POE::],	1139	[Prima:: => AnyEvent::Impl::POE::],
736	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1140	# 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	1141	# byzantine signal and broken child handling, among others.
738	[Glib:: => AnyEvent::Impl::Glib::],	1142	# IO::Async is rather hard to detect, as it doesn't have any
739	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1143	# obvious default class.
740	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1144	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
741	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1145	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1146	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
742	);	1147	);
743		1148
744	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1149	our %method = map +($_ => 1),
		1150	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
745		1151
746	our @post_detect;	1152	our @post_detect;
747		1153
748	sub post_detect(&) {	1154	sub post_detect(&) {
749	my ($cb) = @_;	1155	my ($cb) = @_;
750		1156
751	if ($MODEL) {	1157	if ($MODEL) {
752	$cb->();	1158	$cb->();
753		1159
754	1	1160	undef
755	} else {	1161	} else {
756	push @post_detect, $cb;	1162	push @post_detect, $cb;
757		1163
758	defined wantarray	1164	defined wantarray
759	? bless \$cb, "AnyEvent::Util::PostDetect"	1165	? bless \$cb, "AnyEvent::Util::postdetect"
760	: ()	1166	: ()
761	}	1167	}
762	}	1168	}
763		1169
764	sub AnyEvent::Util::PostDetect::DESTROY {	1170	sub AnyEvent::Util::postdetect::DESTROY {
765	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1171	@post_detect = grep $_ != ${$_[0]}, @post_detect;
766	}	1172	}
767		1173
768	sub detect() {	1174	sub detect() {
769	unless ($MODEL) {	1175	unless ($MODEL) {
770	no strict 'refs';	1176	local $SIG{__DIE__};
771		1177
772	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1178	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
773	my $model = "AnyEvent::Impl::$1";	1179	my $model = "AnyEvent::Impl::$1";
774	if (eval "require $model") {	1180	if (eval "require $model") {
775	$MODEL = $model;	1181	$MODEL = $model;
776	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1182	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
777	} else {	1183	} else {
778	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1184	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
779	}	1185	}
780	}	1186	}
781		1187
782	# check for already loaded models	1188	# check for already loaded models
783	unless ($MODEL) {	1189	unless ($MODEL) {
784	for (@REGISTRY, @models) {	1190	for (@REGISTRY, @models) {
785	my ($package, $model) = @$_;	1191	my ($package, $model) = @$_;
786	if (${"$package\::VERSION"} > 0) {	1192	if (${"$package\::VERSION"} > 0) {
787	if (eval "require $model") {	1193	if (eval "require $model") {
788	$MODEL = $model;	1194	$MODEL = $model;
789	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1195	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
790	last;	1196	last;
791	}	1197	}
792	}	1198	}
793	}	1199	}
794		1200
795	unless ($MODEL) {	1201	unless ($MODEL) {
796	# try to load a model	1202	# try to autoload a model
797
798	for (@REGISTRY, @models) {	1203	for (@REGISTRY, @models) {
799	my ($package, $model) = @$_;	1204	my ($package, $model, $autoload) = @$_;
		1205	if (
		1206	$autoload
800	if (eval "require $package"	1207	and eval "require $package"
801	and ${"$package\::VERSION"} > 0	1208	and ${"$package\::VERSION"} > 0
802	and eval "require $model") {	1209	and eval "require $model"
		1210	) {
803	$MODEL = $model;	1211	$MODEL = $model;
804	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1212	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
805	last;	1213	last;
806	}	1214	}
807	}	1215	}
808		1216
809	$MODEL	1217	$MODEL
810	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1218	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
811	}	1219	}
812	}	1220	}
813		1221
		1222	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1223
814	unshift @ISA, $MODEL;	1224	unshift @ISA, $MODEL;
815	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1225
		1226	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
816		1227
817	(shift @post_detect)->() while @post_detect;	1228	(shift @post_detect)->() while @post_detect;
818	}	1229	}
819		1230
820	$MODEL	1231	$MODEL
…		…
822		1233
823	sub AUTOLOAD {	1234	sub AUTOLOAD {
824	(my $func = $AUTOLOAD) =~ s/.*://;	1235	(my $func = $AUTOLOAD) =~ s/.*://;
825		1236
826	$method{$func}	1237	$method{$func}
827	or croak "$func: not a valid method for AnyEvent objects";	1238	or Carp::croak "$func: not a valid method for AnyEvent objects";
828		1239
829	detect unless $MODEL;	1240	detect unless $MODEL;
830		1241
831	my $class = shift;	1242	my $class = shift;
832	$class->$func (@_);	1243	$class->$func (@_);
833	}	1244	}
834		1245
		1246	# utility function to dup a filehandle. this is used by many backends
		1247	# to support binding more than one watcher per filehandle (they usually
		1248	# allow only one watcher per fd, so we dup it to get a different one).
		1249	sub _dupfh($$;$$) {
		1250	my ($poll, $fh, $r, $w) = @_;
		1251
		1252	# cygwin requires the fh mode to be matching, unix doesn't
		1253	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1254
		1255	open my $fh2, $mode, $fh
		1256	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1257
		1258	# we assume CLOEXEC is already set by perl in all important cases
		1259
		1260	($fh2, $rw)
		1261	}
		1262
835	package AnyEvent::Base;	1263	package AnyEvent::Base;
836		1264
		1265	# default implementations for many methods
		1266
		1267	sub _time {
		1268	# probe for availability of Time::HiRes
		1269	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1270	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1271	*_time = \&Time::HiRes::time;
		1272	# if (eval "use POSIX (); (POSIX::times())...
		1273	} else {
		1274	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1275	*_time = sub { time }; # epic fail
		1276	}
		1277
		1278	&_time
		1279	}
		1280
		1281	sub time { _time }
		1282	sub now { _time }
		1283	sub now_update { }
		1284
837	# default implementation for ->condvar	1285	# default implementation for ->condvar
838		1286
839	sub condvar {	1287	sub condvar {
840	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1288	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
841	}	1289	}
842		1290
843	# default implementation for ->signal	1291	# default implementation for ->signal
844		1292
845	our %SIG_CB;	1293	our $HAVE_ASYNC_INTERRUPT;
		1294	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1295	our (%SIG_ASY, %SIG_ASY_W);
		1296	our ($SIG_COUNT, $SIG_TW);
846		1297
		1298	sub _signal_exec {
		1299	$HAVE_ASYNC_INTERRUPT
		1300	? $SIGPIPE_R->drain
		1301	: sysread $SIGPIPE_R, my $dummy, 9;
		1302
		1303	while (%SIG_EV) {
		1304	for (keys %SIG_EV) {
		1305	delete $SIG_EV{$_};
		1306	$_->() for values %{ $SIG_CB{$_} || {} };
		1307	}
		1308	}
		1309	}
		1310
		1311	# install a dummy wakeup watcher to reduce signal catching latency
		1312	sub _sig_add() {
		1313	unless ($SIG_COUNT++) {
		1314	# try to align timer on a full-second boundary, if possible
		1315	my $NOW = AnyEvent->now;
		1316
		1317	$SIG_TW = AnyEvent->timer (
		1318	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1319	interval => $MAX_SIGNAL_LATENCY,
		1320	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1321	);
		1322	}
		1323	}
		1324
		1325	sub _sig_del {
		1326	undef $SIG_TW
		1327	unless --$SIG_COUNT;
		1328	}
		1329
847	sub signal {	1330	sub _signal {
848	my (undef, %arg) = @_;	1331	my (undef, %arg) = @_;
849		1332
850	my $signal = uc $arg{signal}	1333	my $signal = uc $arg{signal}
851	or Carp::croak "required option 'signal' is missing";	1334	or Carp::croak "required option 'signal' is missing";
852		1335
		1336	if ($HAVE_ASYNC_INTERRUPT) {
		1337	# async::interrupt
		1338
		1339	$signal = Async::Interrupt::sig2num ($signal);
853	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1340	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1341
		1342	$SIG_ASY{$signal} ||= new Async::Interrupt
		1343	cb => sub { undef $SIG_EV{$signal} },
		1344	signal => $signal,
		1345	pipe => [$SIGPIPE_R->filenos],
		1346	pipe_autodrain => 0,
		1347	;
		1348
		1349	} else {
		1350	# pure perl
		1351
		1352	# AE::Util has been loaded in signal
		1353	$signal = AnyEvent::Util::sig2name ($signal);
		1354	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1355
854	$SIG{$signal} ||= sub {	1356	$SIG{$signal} ||= sub {
855	$_->() for values %{ $SIG_CB{$signal} || {} };	1357	local $!;
		1358	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1359	undef $SIG_EV{$signal};
		1360	};
		1361
		1362	# can't do signal processing without introducing races in pure perl,
		1363	# so limit the signal latency.
		1364	_sig_add;
856	};	1365	}
857		1366
858	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1367	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
859	}	1368	}
860		1369
		1370	sub signal {
		1371	# probe for availability of Async::Interrupt
		1372	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 1.0 (); 1") {
		1373	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1374
		1375	$HAVE_ASYNC_INTERRUPT = 1;
		1376	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1377	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1378
		1379	} else {
		1380	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1381
		1382	require Fcntl;
		1383
		1384	if (AnyEvent::WIN32) {
		1385	require AnyEvent::Util;
		1386
		1387	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1388	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1389	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1390	} else {
		1391	pipe $SIGPIPE_R, $SIGPIPE_W;
		1392	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1393	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1394
		1395	# not strictly required, as $^F is normally 2, but let's make sure...
		1396	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1397	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1398	}
		1399
		1400	$SIGPIPE_R
		1401	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1402
		1403	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1404	}
		1405
		1406	*signal = \&_signal;
		1407	&signal
		1408	}
		1409
861	sub AnyEvent::Base::Signal::DESTROY {	1410	sub AnyEvent::Base::signal::DESTROY {
862	my ($signal, $cb) = @{$_[0]};	1411	my ($signal, $cb) = @{$_[0]};
863		1412
		1413	_sig_del;
		1414
864	delete $SIG_CB{$signal}{$cb};	1415	delete $SIG_CB{$signal}{$cb};
865		1416
866	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1417	$HAVE_ASYNC_INTERRUPT
		1418	? delete $SIG_ASY{$signal}
		1419	: # delete doesn't work with older perls - they then
		1420	# print weird messages, or just unconditionally exit
		1421	# instead of getting the default action.
		1422	undef $SIG{$signal}
		1423	unless keys %{ $SIG_CB{$signal} };
867	}	1424	}
868		1425
869	# default implementation for ->child	1426	# default implementation for ->child
870		1427
871	our %PID_CB;	1428	our %PID_CB;
872	our $CHLD_W;	1429	our $CHLD_W;
873	our $CHLD_DELAY_W;	1430	our $CHLD_DELAY_W;
874	our $PID_IDLE;
875	our $WNOHANG;	1431	our $WNOHANG;
876		1432
877	sub _child_wait {	1433	sub _emit_childstatus($$) {
878	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1434	my (undef, $rpid, $rstatus) = @_;
		1435
		1436	$_->($rpid, $rstatus)
879	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1437	for values %{ $PID_CB{$rpid} || {} },
880	(values %{ $PID_CB{0} || {} });	1438	values %{ $PID_CB{0} || {} };
881	}
882
883	undef $PID_IDLE;
884	}	1439	}
885		1440
886	sub _sigchld {	1441	sub _sigchld {
887	# make sure we deliver these changes "synchronous" with the event loop.	1442	my $pid;
888	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1443
889	undef $CHLD_DELAY_W;	1444	AnyEvent->_emit_childstatus ($pid, $?)
890	&_child_wait;	1445	while ($pid = waitpid -1, $WNOHANG) > 0;
891	});
892	}	1446	}
893		1447
894	sub child {	1448	sub child {
895	my (undef, %arg) = @_;	1449	my (undef, %arg) = @_;
896		1450
897	defined (my $pid = $arg{pid} + 0)	1451	defined (my $pid = $arg{pid} + 0)
898	or Carp::croak "required option 'pid' is missing";	1452	or Carp::croak "required option 'pid' is missing";
899		1453
900	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1454	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
901		1455
902	unless ($WNOHANG) {	1456	# WNOHANG is almost cetrainly 1 everywhere
903	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1457	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
904	}	1458	? 1
		1459	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
905		1460
906	unless ($CHLD_W) {	1461	unless ($CHLD_W) {
907	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1462	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
908	# child could be a zombie already, so make at least one round	1463	# child could be a zombie already, so make at least one round
909	&_sigchld;	1464	&_sigchld;
910	}	1465	}
911		1466
912	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1467	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
913	}	1468	}
914		1469
915	sub AnyEvent::Base::Child::DESTROY {	1470	sub AnyEvent::Base::child::DESTROY {
916	my ($pid, $cb) = @{$_[0]};	1471	my ($pid, $cb) = @{$_[0]};
917		1472
918	delete $PID_CB{$pid}{$cb};	1473	delete $PID_CB{$pid}{$cb};
919	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1474	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
920		1475
921	undef $CHLD_W unless keys %PID_CB;	1476	undef $CHLD_W unless keys %PID_CB;
922	}	1477	}
923		1478
		1479	# idle emulation is done by simply using a timer, regardless
		1480	# of whether the process is idle or not, and not letting
		1481	# the callback use more than 50% of the time.
		1482	sub idle {
		1483	my (undef, %arg) = @_;
		1484
		1485	my ($cb, $w, $rcb) = $arg{cb};
		1486
		1487	$rcb = sub {
		1488	if ($cb) {
		1489	$w = _time;
		1490	&$cb;
		1491	$w = _time - $w;
		1492
		1493	# never use more then 50% of the time for the idle watcher,
		1494	# within some limits
		1495	$w = 0.0001 if $w < 0.0001;
		1496	$w = 5 if $w > 5;
		1497
		1498	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1499	} else {
		1500	# clean up...
		1501	undef $w;
		1502	undef $rcb;
		1503	}
		1504	};
		1505
		1506	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1507
		1508	bless \\$cb, "AnyEvent::Base::idle"
		1509	}
		1510
		1511	sub AnyEvent::Base::idle::DESTROY {
		1512	undef $${$_[0]};
		1513	}
		1514
924	package AnyEvent::CondVar;	1515	package AnyEvent::CondVar;
925		1516
926	our @ISA = AnyEvent::CondVar::Base::;	1517	our @ISA = AnyEvent::CondVar::Base::;
927		1518
928	package AnyEvent::CondVar::Base;	1519	package AnyEvent::CondVar::Base;
929		1520
930	use overload	1521	#use overload
931	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1522	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
932	fallback => 1;	1523	# fallback => 1;
		1524
		1525	# save 300+ kilobytes by dirtily hardcoding overloading
		1526	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1527	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1528	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1529	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1530
		1531	our $WAITING;
933		1532
934	sub _send {	1533	sub _send {
935	# nop	1534	# nop
936	}	1535	}
937		1536
…		…
950	sub ready {	1549	sub ready {
951	$_[0]{_ae_sent}	1550	$_[0]{_ae_sent}
952	}	1551	}
953		1552
954	sub _wait {	1553	sub _wait {
		1554	$WAITING
		1555	and !$_[0]{_ae_sent}
		1556	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1557
		1558	local $WAITING = 1;
955	AnyEvent->one_event while !$_[0]{_ae_sent};	1559	AnyEvent->one_event while !$_[0]{_ae_sent};
956	}	1560	}
957		1561
958	sub recv {	1562	sub recv {
959	$_[0]->_wait;	1563	$_[0]->_wait;
…		…
978	}	1582	}
979		1583
980	# undocumented/compatibility with pre-3.4	1584	# undocumented/compatibility with pre-3.4
981	*broadcast = \&send;	1585	*broadcast = \&send;
982	*wait = \&_wait;	1586	*wait = \&_wait;
		1587
		1588	=head1 ERROR AND EXCEPTION HANDLING
		1589
		1590	In general, AnyEvent does not do any error handling - it relies on the
		1591	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1592	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1593	checking of all AnyEvent methods, however, which is highly useful during
		1594	development.
		1595
		1596	As for exception handling (i.e. runtime errors and exceptions thrown while
		1597	executing a callback), this is not only highly event-loop specific, but
		1598	also not in any way wrapped by this module, as this is the job of the main
		1599	program.
		1600
		1601	The pure perl event loop simply re-throws the exception (usually
		1602	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1603	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1604	so on.
		1605
		1606	=head1 ENVIRONMENT VARIABLES
		1607
		1608	The following environment variables are used by this module or its
		1609	submodules.
		1610
		1611	Note that AnyEvent will remove I<all> environment variables starting with
		1612	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1613	enabled.
		1614
		1615	=over 4
		1616
		1617	=item C<PERL_ANYEVENT_VERBOSE>
		1618
		1619	By default, AnyEvent will be completely silent except in fatal
		1620	conditions. You can set this environment variable to make AnyEvent more
		1621	talkative.
		1622
		1623	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1624	conditions, such as not being able to load the event model specified by
		1625	C<PERL_ANYEVENT_MODEL>.
		1626
		1627	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1628	model it chooses.
		1629
		1630	When set to C<8> or higher, then AnyEvent will report extra information on
		1631	which optional modules it loads and how it implements certain features.
		1632
		1633	=item C<PERL_ANYEVENT_STRICT>
		1634
		1635	AnyEvent does not do much argument checking by default, as thorough
		1636	argument checking is very costly. Setting this variable to a true value
		1637	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1638	check the arguments passed to most method calls. If it finds any problems,
		1639	it will croak.
		1640
		1641	In other words, enables "strict" mode.
		1642
		1643	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1644	>>, it is definitely recommended to keep it off in production. Keeping
		1645	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1646	can be very useful, however.
		1647
		1648	=item C<PERL_ANYEVENT_MODEL>
		1649
		1650	This can be used to specify the event model to be used by AnyEvent, before
		1651	auto detection and -probing kicks in. It must be a string consisting
		1652	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1653	and the resulting module name is loaded and if the load was successful,
		1654	used as event model. If it fails to load AnyEvent will proceed with
		1655	auto detection and -probing.
		1656
		1657	This functionality might change in future versions.
		1658
		1659	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1660	could start your program like this:
		1661
		1662	PERL_ANYEVENT_MODEL=Perl perl ...
		1663
		1664	=item C<PERL_ANYEVENT_PROTOCOLS>
		1665
		1666	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1667	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1668	of auto probing).
		1669
		1670	Must be set to a comma-separated list of protocols or address families,
		1671	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1672	used, and preference will be given to protocols mentioned earlier in the
		1673	list.
		1674
		1675	This variable can effectively be used for denial-of-service attacks
		1676	against local programs (e.g. when setuid), although the impact is likely
		1677	small, as the program has to handle conenction and other failures anyways.
		1678
		1679	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1680	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1681	- only support IPv4, never try to resolve or contact IPv6
		1682	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1683	IPv6, but prefer IPv6 over IPv4.
		1684
		1685	=item C<PERL_ANYEVENT_EDNS0>
		1686
		1687	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1688	for DNS. This extension is generally useful to reduce DNS traffic, but
		1689	some (broken) firewalls drop such DNS packets, which is why it is off by
		1690	default.
		1691
		1692	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1693	EDNS0 in its DNS requests.
		1694
		1695	=item C<PERL_ANYEVENT_MAX_FORKS>
		1696
		1697	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1698	will create in parallel.
		1699
		1700	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1701
		1702	The default value for the C<max_outstanding> parameter for the default DNS
		1703	resolver - this is the maximum number of parallel DNS requests that are
		1704	sent to the DNS server.
		1705
		1706	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1707
		1708	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1709	configuration) in the default resolver. When set to the empty string, no
		1710	default config will be used.
		1711
		1712	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1713
		1714	When neither C<ca_file> nor C<ca_path> was specified during
		1715	L<AnyEvent::TLS> context creation, and either of these environment
		1716	variables exist, they will be used to specify CA certificate locations
		1717	instead of a system-dependent default.
		1718
		1719	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1720
		1721	When these are set to C<1>, then the respective modules are not
		1722	loaded. Mostly good for testing AnyEvent itself.
		1723
		1724	=back
983		1725
984	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1726	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
985		1727
986	This is an advanced topic that you do not normally need to use AnyEvent in	1728	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	1729	a module. This section is only of use to event loop authors who want to
…		…
1021		1763
1022	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1764	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1023	condition variables: code blocking while waiting for a condition will	1765	condition variables: code blocking while waiting for a condition will
1024	C<die>. This still works with most modules/usages, and blocking calls must	1766	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.	1767	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		1768
1095	=head1 EXAMPLE PROGRAM	1769	=head1 EXAMPLE PROGRAM
1096		1770
1097	The following program uses an I/O watcher to read data from STDIN, a timer	1771	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	1772	to display a message once per second, and a condition variable to quit the
…		…
1292	watcher.	1966	watcher.
1293		1967
1294	=head3 Results	1968	=head3 Results
1295		1969
1296	name watchers bytes create invoke destroy comment	1970	name watchers bytes create invoke destroy comment
1297	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1971	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	1972	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	1973	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	1974	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	1975	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	1976	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1977	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1978	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	1979	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	1980	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	1981	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	1982	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1307		1983
1308	=head3 Discussion	1984	=head3 Discussion
1309		1985
1310	The benchmark does I<not> measure scalability of the event loop very	1986	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)	1987	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	2012	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.	2013	them active), of course, but this was not subject of this benchmark.
1338		2014
1339	The C<Event> module has a relatively high setup and callback invocation	2015	The C<Event> module has a relatively high setup and callback invocation
1340	cost, but overall scores in on the third place.	2016	cost, but overall scores in on the third place.
		2017
		2018	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2019	when using its pure perl backend.
1341		2020
1342	C<Glib>'s memory usage is quite a bit higher, but it features a	2021	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	2022	faster callback invocation and overall ends up in the same class as
1344	C<Event>. However, Glib scales extremely badly, doubling the number of	2023	C<Event>. However, Glib scales extremely badly, doubling the number of
1345	watchers increases the processing time by more than a factor of four,	2024	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	2102	it to another server. This includes deleting the old timeout and creating
1424	a new one that moves the timeout into the future.	2103	a new one that moves the timeout into the future.
1425		2104
1426	=head3 Results	2105	=head3 Results
1427		2106
1428	name sockets create request	2107	name sockets create request
1429	EV 20000 69.01 11.16	2108	EV 20000 69.01 11.16
1430	Perl 20000 73.32 35.87	2109	Perl 20000 73.32 35.87
		2110	IOAsync 20000 157.00 98.14 epoll
		2111	IOAsync 20000 159.31 616.06 poll
1431	Event 20000 212.62 257.32	2112	Event 20000 212.62 257.32
1432	Glib 20000 651.16 1896.30	2113	Glib 20000 651.16 1896.30
1433	POE 20000 349.67 12317.24 uses POE::Loop::Event	2114	POE 20000 349.67 12317.24 uses POE::Loop::Event
1434		2115
1435	=head3 Discussion	2116	=head3 Discussion
1436		2117
1437	This benchmark I<does> measure scalability and overall performance of the	2118	This benchmark I<does> measure scalability and overall performance of the
1438	particular event loop.	2119	particular event loop.
…		…
1440	EV is again fastest. Since it is using epoll on my system, the setup time	2121	EV is again fastest. Since it is using epoll on my system, the setup time
1441	is relatively high, though.	2122	is relatively high, though.
1442		2123
1443	Perl surprisingly comes second. It is much faster than the C-based event	2124	Perl surprisingly comes second. It is much faster than the C-based event
1444	loops Event and Glib.	2125	loops Event and Glib.
		2126
		2127	IO::Async performs very well when using its epoll backend, and still quite
		2128	good compared to Glib when using its pure perl backend.
1445		2129
1446	Event suffers from high setup time as well (look at its code and you will	2130	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	2131	understand why). Callback invocation also has a high overhead compared to
1448	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2132	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1449	uses select or poll in basically all documented configurations.	2133	uses select or poll in basically all documented configurations.
…		…
1512	=item * C-based event loops perform very well with small number of	2196	=item * C-based event loops perform very well with small number of
1513	watchers, as the management overhead dominates.	2197	watchers, as the management overhead dominates.
1514		2198
1515	=back	2199	=back
1516		2200
		2201	=head2 THE IO::Lambda BENCHMARK
		2202
		2203	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2204	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2205	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2206	shouldn't come as a surprise to anybody). As such, the benchmark is
		2207	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2208	very optimal. But how would AnyEvent compare when used without the extra
		2209	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2210
		2211	The benchmark itself creates an echo-server, and then, for 500 times,
		2212	connects to the echo server, sends a line, waits for the reply, and then
		2213	creates the next connection. This is a rather bad benchmark, as it doesn't
		2214	test the efficiency of the framework or much non-blocking I/O, but it is a
		2215	benchmark nevertheless.
		2216
		2217	name runtime
		2218	Lambda/select 0.330 sec
		2219	+ optimized 0.122 sec
		2220	Lambda/AnyEvent 0.327 sec
		2221	+ optimized 0.138 sec
		2222	Raw sockets/select 0.077 sec
		2223	POE/select, components 0.662 sec
		2224	POE/select, raw sockets 0.226 sec
		2225	POE/select, optimized 0.404 sec
		2226
		2227	AnyEvent/select/nb 0.085 sec
		2228	AnyEvent/EV/nb 0.068 sec
		2229	+state machine 0.134 sec
		2230
		2231	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2232	benchmarks actually make blocking connects and use 100% blocking I/O,
		2233	defeating the purpose of an event-based solution. All of the newly
		2234	written AnyEvent benchmarks use 100% non-blocking connects (using
		2235	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2236	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2237	generally require a lot more bookkeeping and event handling than blocking
		2238	connects (which involve a single syscall only).
		2239
		2240	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2241	offers similar expressive power as POE and IO::Lambda, using conventional
		2242	Perl syntax. This means that both the echo server and the client are 100%
		2243	non-blocking, further placing it at a disadvantage.
		2244
		2245	As you can see, the AnyEvent + EV combination even beats the
		2246	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2247	backend easily beats IO::Lambda and POE.
		2248
		2249	And even the 100% non-blocking version written using the high-level (and
		2250	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2251	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2252	in a non-blocking way.
		2253
		2254	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2255	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2256	part of the IO::lambda distribution and were used without any changes.
		2257
		2258
		2259	=head1 SIGNALS
		2260
		2261	AnyEvent currently installs handlers for these signals:
		2262
		2263	=over 4
		2264
		2265	=item SIGCHLD
		2266
		2267	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2268	emulation for event loops that do not support them natively. Also, some
		2269	event loops install a similar handler.
		2270
		2271	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2272	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2273
		2274	=item SIGPIPE
		2275
		2276	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2277	when AnyEvent gets loaded.
		2278
		2279	The rationale for this is that AnyEvent users usually do not really depend
		2280	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2281	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2282	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2283	some random socket.
		2284
		2285	The rationale for installing a no-op handler as opposed to ignoring it is
		2286	that this way, the handler will be restored to defaults on exec.
		2287
		2288	Feel free to install your own handler, or reset it to defaults.
		2289
		2290	=back
		2291
		2292	=cut
		2293
		2294	undef $SIG{CHLD}
		2295	if $SIG{CHLD} eq 'IGNORE';
		2296
		2297	$SIG{PIPE} = sub { }
		2298	unless defined $SIG{PIPE};
		2299
		2300	=head1 RECOMMENDED/OPTIONAL MODULES
		2301
		2302	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2303	it's built-in modules) are required to use it.
		2304
		2305	That does not mean that AnyEvent won't take advantage of some additional
		2306	modules if they are installed.
		2307
		2308	This section epxlains which additional modules will be used, and how they
		2309	affect AnyEvent's operetion.
		2310
		2311	=over 4
		2312
		2313	=item L<Async::Interrupt>
		2314
		2315	This slightly arcane module is used to implement fast signal handling: To
		2316	my knowledge, there is no way to do completely race-free and quick
		2317	signal handling in pure perl. To ensure that signals still get
		2318	delivered, AnyEvent will start an interval timer to wake up perl (and
		2319	catch the signals) with some delay (default is 10 seconds, look for
		2320	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2321
		2322	If this module is available, then it will be used to implement signal
		2323	catching, which means that signals will not be delayed, and the event loop
		2324	will not be interrupted regularly, which is more efficient (And good for
		2325	battery life on laptops).
		2326
		2327	This affects not just the pure-perl event loop, but also other event loops
		2328	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2329
		2330	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2331	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2332	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2333	does nothing for those backends.
		2334
		2335	=item L<EV>
		2336
		2337	This module isn't really "optional", as it is simply one of the backend
		2338	event loops that AnyEvent can use. However, it is simply the best event
		2339	loop available in terms of features, speed and stability: It supports
		2340	the AnyEvent API optimally, implements all the watcher types in XS, does
		2341	automatic timer adjustments even when no monotonic clock is available,
		2342	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2343	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2344	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2345
		2346	=item L<Guard>
		2347
		2348	The guard module, when used, will be used to implement
		2349	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2350	lot less memory), but otherwise doesn't affect guard operation much. It is
		2351	purely used for performance.
		2352
		2353	=item L<JSON> and L<JSON::XS>
		2354
		2355	This module is required when you want to read or write JSON data via
		2356	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2357	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2358
		2359	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2360	installed.
		2361
		2362	=item L<Net::SSLeay>
		2363
		2364	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2365	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2366	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2367
		2368	=item L<Time::HiRes>
		2369
		2370	This module is part of perl since release 5.008. It will be used when the
		2371	chosen event library does not come with a timing source on it's own. The
		2372	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2373	try to use a monotonic clock for timing stability.
		2374
		2375	=back
		2376
1517		2377
1518	=head1 FORK	2378	=head1 FORK
1519		2379
1520	Most event libraries are not fork-safe. The ones who are usually are	2380	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>	2381	because they rely on inefficient but fork-safe C<select> or C<poll>
1522	calls. Only L<EV> is fully fork-aware.	2382	calls. Only L<EV> is fully fork-aware.
1523		2383
1524	If you have to fork, you must either do so I<before> creating your first	2384	If you have to fork, you must either do so I<before> creating your first
1525	watcher OR you must not use AnyEvent at all in the child.	2385	watcher OR you must not use AnyEvent at all in the child OR you must do
		2386	something completely out of the scope of AnyEvent.
1526		2387
1527		2388
1528	=head1 SECURITY CONSIDERATIONS	2389	=head1 SECURITY CONSIDERATIONS
1529		2390
1530	AnyEvent can be forced to load any event model via	2391	AnyEvent can be forced to load any event model via
…		…
1535	specified in the variable.	2396	specified in the variable.
1536		2397
1537	You can make AnyEvent completely ignore this variable by deleting it	2398	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:	2399	before the first watcher gets created, e.g. with a C<BEGIN> block:
1539		2400
1540	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2401	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1541		2402
1542	use AnyEvent;	2403	use AnyEvent;
1543		2404
1544	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2405	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	2406	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).	2407	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2408	$ENV{PERL_ANYEVENT_STRICT}.
		2409
		2410	Note that AnyEvent will remove I<all> environment variables starting with
		2411	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2412	enabled.
		2413
		2414
		2415	=head1 BUGS
		2416
		2417	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2418	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2419	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2420	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2421	pronounced).
1547		2422
1548		2423
1549	=head1 SEE ALSO	2424	=head1 SEE ALSO
1550		2425
1551	Utility functions: L<AnyEvent::Util>.	2426	Utility functions: L<AnyEvent::Util>.
…		…
1554	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2429	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1555		2430
1556	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2431	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1557	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2432	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1558	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2433	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1559	L<AnyEvent::Impl::POE>.	2434	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1560		2435
1561	Non-blocking file handles, sockets, TCP clients and	2436	Non-blocking file handles, sockets, TCP clients and
1562	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2437	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1563		2438
1564	Asynchronous DNS: L<AnyEvent::DNS>.	2439	Asynchronous DNS: L<AnyEvent::DNS>.
1565		2440
1566	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2441	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2442	L<Coro::Event>,
1567		2443
1568	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2444	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2445	L<AnyEvent::HTTP>.
1569		2446
1570		2447
1571	=head1 AUTHOR	2448	=head1 AUTHOR
1572		2449
1573	Marc Lehmann <schmorp@schmorp.de>	2450	Marc Lehmann <schmorp@schmorp.de>
1574	http://home.schmorp.de/	2451	http://home.schmorp.de/
1575		2452
1576	=cut	2453	=cut
1577		2454
1578	1	2455	1
1579		2456

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