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Revision 1.139 by root, Mon May 26 06:04:38 2008 UTC vs.
Revision 1.290 by root, Tue Sep 1 18:27:46 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
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	192	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
144		194
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	195	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		196	for events (AnyEvent might or might not keep a reference to this file
		197	handle). Note that only file handles pointing to things for which
		198	non-blocking operation makes sense are allowed. This includes sockets,
		199	most character devices, pipes, fifos and so on, but not for example files
		200	or block devices.
		201
146	for events. C<poll> must be a string that is either C<r> or C<w>,	202	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,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
148	respectively. C<cb> is the callback to invoke each time the file handle	205	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		206
151	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
154		210
…		…
158		214
159	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	216	always use non-blocking calls when reading/writing from/to your file
161	handles.	217	handles.
162		218
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	219	Example: wait for readability of STDIN, then read a line and disable the
		220	watcher.
		221
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	224	warn "read: $input\n";
169	undef $w;	225	undef $w;
170	});	226	});
171		227
172	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
173		229
		230	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		231
		232	$w = AnyEvent->timer (
		233	after => <fractional_seconds>,
		234	interval => <fractional_seconds>,
		235	cb => <callback>,
		236	);
		237
174	You can create a time watcher by calling the C<< AnyEvent->timer >>	238	You can create a time watcher by calling the C<< AnyEvent->timer >>
175	method with the following mandatory arguments:	239	method with the following mandatory arguments:
176		240
177	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
178	supported) the callback should be invoked. C<cb> is the callback to invoke	242	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
180		244
181	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
184		248
185	The timer callback will be invoked at most once: if you want a repeating	249	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	250	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	251	callback will be invoked regularly at that interval (in fractional
		252	seconds) after the first invocation. If C<interval> is specified with a
		253	false value, then it is treated as if it were missing.
188		254
189	Example:	255	The callback will be rescheduled before invoking the callback, but no
		256	attempt is done to avoid timer drift in most backends, so the interval is
		257	only approximate.
190		258
191	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	262	warn "timeout\n";
194	});	263	});
195		264
196	# to cancel the timer:	265	# to cancel the timer:
197	undef $w;	266	undef $w;
198		267
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	268	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		269
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
207	};	272	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		273
212	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
213		275
214	There are two ways to handle timers: based on real time (relative, "fire	276	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	277	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	289	timers.
228		290
229	AnyEvent always prefers relative timers, if available, matching the	291	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	292	AnyEvent API.
231		293
		294	AnyEvent has two additional methods that return the "current time":
		295
		296	=over 4
		297
		298	=item AnyEvent->time
		299
		300	This returns the "current wallclock time" as a fractional number of
		301	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		302	return, and the result is guaranteed to be compatible with those).
		303
		304	It progresses independently of any event loop processing, i.e. each call
		305	will check the system clock, which usually gets updated frequently.
		306
		307	=item AnyEvent->now
		308
		309	This also returns the "current wallclock time", but unlike C<time>, above,
		310	this value might change only once per event loop iteration, depending on
		311	the event loop (most return the same time as C<time>, above). This is the
		312	time that AnyEvent's timers get scheduled against.
		313
		314	I<In almost all cases (in all cases if you don't care), this is the
		315	function to call when you want to know the current time.>
		316
		317	This function is also often faster then C<< AnyEvent->time >>, and
		318	thus the preferred method if you want some timestamp (for example,
		319	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		320
		321	The rest of this section is only of relevance if you try to be very exact
		322	with your timing, you can skip it without bad conscience.
		323
		324	For a practical example of when these times differ, consider L<Event::Lib>
		325	and L<EV> and the following set-up:
		326
		327	The event loop is running and has just invoked one of your callback at
		328	time=500 (assume no other callbacks delay processing). In your callback,
		329	you wait a second by executing C<sleep 1> (blocking the process for a
		330	second) and then (at time=501) you create a relative timer that fires
		331	after three seconds.
		332
		333	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		334	both return C<501>, because that is the current time, and the timer will
		335	be scheduled to fire at time=504 (C<501> + C<3>).
		336
		337	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		338	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		339	last event processing phase started. With L<EV>, your timer gets scheduled
		340	to run at time=503 (C<500> + C<3>).
		341
		342	In one sense, L<Event::Lib> is more exact, as it uses the current time
		343	regardless of any delays introduced by event processing. However, most
		344	callbacks do not expect large delays in processing, so this causes a
		345	higher drift (and a lot more system calls to get the current time).
		346
		347	In another sense, L<EV> is more exact, as your timer will be scheduled at
		348	the same time, regardless of how long event processing actually took.
		349
		350	In either case, if you care (and in most cases, you don't), then you
		351	can get whatever behaviour you want with any event loop, by taking the
		352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		353	account.
		354
		355	=item AnyEvent->now_update
		356
		357	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		358	the current time for each loop iteration (see the discussion of L<<
		359	AnyEvent->now >>, above).
		360
		361	When a callback runs for a long time (or when the process sleeps), then
		362	this "current" time will differ substantially from the real time, which
		363	might affect timers and time-outs.
		364
		365	When this is the case, you can call this method, which will update the
		366	event loop's idea of "current time".
		367
		368	Note that updating the time I<might> cause some events to be handled.
		369
		370	=back
		371
232	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
233		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
234	You can watch for signals using a signal watcher, C<signal> is the signal	376	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	377	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
237		379
238	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	381	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	382	callbacks cannot use arguments passed to signal watcher callbacks.
241		383
…		…
243	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	386	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.	387	but it is guaranteed not to interrupt any other callbacks.
246		388
247	The main advantage of using these watchers is that you can share a signal	389	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
249		392
250	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
252		396
253	Example: exit on SIGINT	397	Example: exit on SIGINT
254		398
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		409	variable can be changed only before the first signal watcher is created,
		410	and should be left alone otherwise. This variable determines how often
		411	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		412	will cause fewer spurious wake-ups, which is better for power and CPU
		413	saving.
		414
		415	All these problems can be avoided by installing the optional
		416	L<Async::Interrupt> module, which works with most event loops. It will not
		417	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		418	(and not with L<POE> currently, as POE does it's own workaround with
		419	one-second latency). For those, you just have to suffer the delays.
		420
257	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
258		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
259	You can also watch on a child process exit and catch its exit status.	425	You can also watch on a child process exit and catch its exit status.
260		426
261	The child process is specified by the C<pid> argument (if set to C<0>, it	427	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	428	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	429	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	430	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,	431	(stopped/continued).
266	you I<can> rely on child watcher callback arguments.	432
		433	The callback will be called with the pid and exit status (as returned by
		434	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		435	callback arguments.
		436
		437	This watcher type works by installing a signal handler for C<SIGCHLD>,
		438	and since it cannot be shared, nothing else should use SIGCHLD or reap
		439	random child processes (waiting for specific child processes, e.g. inside
		440	C<system>, is just fine).
267		441
268	There is a slight catch to child watchers, however: you usually start them	442	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	443	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
271		445
272	Not all event models handle this correctly (POE doesn't), but even for	446	Not all event models handle this correctly (neither POE nor IO::Async do,
		447	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	448	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).	449	the process exits (i.e. before you fork in the first place). AnyEvent's
		450	pure perl event loop handles all cases correctly regardless of when you
		451	start the watcher.
275		452
276	This means you cannot create a child watcher as the very first thing in an	453	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	454	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>).	455	watcher before you C<fork> the child (alternatively, you can call
		456	C<AnyEvent::detect>).
		457
		458	As most event loops do not support waiting for child events, they will be
		459	emulated by AnyEvent in most cases, in which the latency and race problems
		460	mentioned in the description of signal watchers apply.
279		461
280	Example: fork a process and wait for it	462	Example: fork a process and wait for it
281		463
282	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
283		465
284	my $pid = fork or exit 5;	466	my $pid = fork or exit 5;
285		467
286	my $w = AnyEvent->child (	468	my $w = AnyEvent->child (
287	pid => $pid,	469	pid => $pid,
288	cb => sub {	470	cb => sub {
289	my ($pid, $status) = @_;	471	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	472	warn "pid $pid exited with status $status";
291	$done->send;	473	$done->send;
292	},	474	},
293	);	475	);
294		476
295	# do something else, then wait for process exit	477	# do something else, then wait for process exit
296	$done->recv;	478	$done->recv;
		479
		480	=head2 IDLE WATCHERS
		481
		482	$w = AnyEvent->idle (cb => <callback>);
		483
		484	Sometimes there is a need to do something, but it is not so important
		485	to do it instantly, but only when there is nothing better to do. This
		486	"nothing better to do" is usually defined to be "no other events need
		487	attention by the event loop".
		488
		489	Idle watchers ideally get invoked when the event loop has nothing
		490	better to do, just before it would block the process to wait for new
		491	events. Instead of blocking, the idle watcher is invoked.
		492
		493	Most event loops unfortunately do not really support idle watchers (only
		494	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		495	will simply call the callback "from time to time".
		496
		497	Example: read lines from STDIN, but only process them when the
		498	program is otherwise idle:
		499
		500	my @lines; # read data
		501	my $idle_w;
		502	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		503	push @lines, scalar <STDIN>;
		504
		505	# start an idle watcher, if not already done
		506	$idle_w ||= AnyEvent->idle (cb => sub {
		507	# handle only one line, when there are lines left
		508	if (my $line = shift @lines) {
		509	print "handled when idle: $line";
		510	} else {
		511	# otherwise disable the idle watcher again
		512	undef $idle_w;
		513	}
		514	});
		515	});
297		516
298	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
299		523
300	If you are familiar with some event loops you will know that all of them	524	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	525	require you to run some blocking "loop", "run" or similar function that
302	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
303		527
304	AnyEvent is different, it expects somebody else to run the event loop and	528	AnyEvent is slightly different: it expects somebody else to run the event
305	will only block when necessary (usually when told by the user).	529	loop and will only block when necessary (usually when told by the user).
306		530
307	The instrument to do that is called a "condition variable", so called	531	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	532	because they represent a condition that must become true.
		533
		534	Now is probably a good time to look at the examples further below.
309		535
310	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
312	C<cb>, which specifies a callback to be called when the condition variable	538	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
314		541
315	After creation, the condition variable is "false" until it becomes "true"	542	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	543	by calling the C<send> method (or calling the condition variable as if it
317	were a callback, read about the caveats in the description for the C<<	544	were a callback, read about the caveats in the description for the C<<
318	->send >> method).	545	->send >> method).
…		…
320	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	548	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transactions - each condition variable can be	550	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	551	used to represent a transaction, which finishes at some point and delivers
325	a result.	552	a result. And yet some people know them as "futures" - a promise to
		553	compute/deliver something that you can wait for.
326		554
327	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	556	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	557	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	558	availability of results. The user can either act when the callback is
…		…
364	after => 1,	592	after => 1,
365	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
366	);	594	);
367		595
368	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
369	# calls send	597	# calls ->send
370	$result_ready->recv;	598	$result_ready->recv;
371		599
372	Example: wait for a timer, but take advantage of the fact that	600	Example: wait for a timer, but take advantage of the fact that condition
373	condition variables are also code references.	601	variables are also callable directly.
374		602
375	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
376	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
377	$done->recv;	605	$done->recv;
		606
		607	Example: Imagine an API that returns a condvar and doesn't support
		608	callbacks. This is how you make a synchronous call, for example from
		609	the main program:
		610
		611	use AnyEvent::CouchDB;
		612
		613	...
		614
		615	my @info = $couchdb->info->recv;
		616
		617	And this is how you would just set a callback to be called whenever the
		618	results are available:
		619
		620	$couchdb->info->cb (sub {
		621	my @info = $_[0]->recv;
		622	});
378		623
379	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
380		625
381	These methods should only be used by the producing side, i.e. the	626	These methods should only be used by the producing side, i.e. the
382	code/module that eventually sends the signal. Note that it is also	627	code/module that eventually sends the signal. Note that it is also
…		…
395	immediately from within send.	640	immediately from within send.
396		641
397	Any arguments passed to the C<send> call will be returned by all	642	Any arguments passed to the C<send> call will be returned by all
398	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
399		644
400	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
401	(as a code reference). Calling them directly is the same as calling	646	they were a code reference). Calling them directly is the same as calling
402	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
403	overloading, so as tempting as it may be, passing a condition variable
404	instead of a callback does not work. Both the pure perl and EV loops
405	support overloading, however, as well as all functions that use perl to
406	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407	example).
408		648
409	=item $cv->croak ($error)	649	=item $cv->croak ($error)
410		650
411	Similar to send, but causes all call's to C<< ->recv >> to invoke	651	Similar to send, but causes all call's to C<< ->recv >> to invoke
412	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
413		653
414	This can be used to signal any errors to the condition variable	654	This can be used to signal any errors to the condition variable
415	user/consumer.	655	user/consumer. Doing it this way instead of calling C<croak> directly
		656	delays the error detetcion, but has the overwhelmign advantage that it
		657	diagnoses the error at the place where the result is expected, and not
		658	deep in some event clalback without connection to the actual code causing
		659	the problem.
416		660
417	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
418		662
419	=item $cv->end	663	=item $cv->end
420
421	These two methods are EXPERIMENTAL and MIGHT CHANGE.
422		664
423	These two methods can be used to combine many transactions/events into	665	These two methods can be used to combine many transactions/events into
424	one. For example, a function that pings many hosts in parallel might want	666	one. For example, a function that pings many hosts in parallel might want
425	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
426		668
427	Every call to C<< ->begin >> will increment a counter, and every call to	669	Every call to C<< ->begin >> will increment a counter, and every call to
428	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	670	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
429	>>, the (last) callback passed to C<begin> will be executed. That callback	671	>>, the (last) callback passed to C<begin> will be executed, passing the
430	is I<supposed> to call C<< ->send >>, but that is not required. If no	672	condvar as first argument. That callback is I<supposed> to call C<< ->send
431	callback was set, C<send> will be called without any arguments.	673	>>, but that is not required. If no group callback was set, C<send> will
		674	be called without any arguments.
432		675
433	Let's clarify this with the ping example:	676	You can think of C<< $cv->send >> giving you an OR condition (one call
		677	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		678	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		679
		680	Let's start with a simple example: you have two I/O watchers (for example,
		681	STDOUT and STDERR for a program), and you want to wait for both streams to
		682	close before activating a condvar:
434		683
435	my $cv = AnyEvent->condvar;	684	my $cv = AnyEvent->condvar;
436		685
		686	$cv->begin; # first watcher
		687	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		688	defined sysread $fh1, my $buf, 4096
		689	or $cv->end;
		690	});
		691
		692	$cv->begin; # second watcher
		693	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		694	defined sysread $fh2, my $buf, 4096
		695	or $cv->end;
		696	});
		697
		698	$cv->recv;
		699
		700	This works because for every event source (EOF on file handle), there is
		701	one call to C<begin>, so the condvar waits for all calls to C<end> before
		702	sending.
		703
		704	The ping example mentioned above is slightly more complicated, as the
		705	there are results to be passwd back, and the number of tasks that are
		706	begung can potentially be zero:
		707
		708	my $cv = AnyEvent->condvar;
		709
437	my %result;	710	my %result;
438	$cv->begin (sub { $cv->send (\%result) });	711	$cv->begin (sub { shift->send (\%result) });
439		712
440	for my $host (@list_of_hosts) {	713	for my $host (@list_of_hosts) {
441	$cv->begin;	714	$cv->begin;
442	ping_host_then_call_callback $host, sub {	715	ping_host_then_call_callback $host, sub {
443	$result{$host} = ...;	716	$result{$host} = ...;
…		…
458	loop, which serves two important purposes: first, it sets the callback	731	loop, which serves two important purposes: first, it sets the callback
459	to be called once the counter reaches C<0>, and second, it ensures that	732	to be called once the counter reaches C<0>, and second, it ensures that
460	C<send> is called even when C<no> hosts are being pinged (the loop	733	C<send> is called even when C<no> hosts are being pinged (the loop
461	doesn't execute once).	734	doesn't execute once).
462		735
463	This is the general pattern when you "fan out" into multiple subrequests:	736	This is the general pattern when you "fan out" into multiple (but
464	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	737	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
465	is called at least once, and then, for each subrequest you start, call	738	the callback and ensure C<end> is called at least once, and then, for each
466	C<begin> and for each subrequest you finish, call C<end>.	739	subrequest you start, call C<begin> and for each subrequest you finish,
		740	call C<end>.
467		741
468	=back	742	=back
469		743
470	=head3 METHODS FOR CONSUMERS	744	=head3 METHODS FOR CONSUMERS
471		745
…		…
487	function will call C<croak>.	761	function will call C<croak>.
488		762
489	In list context, all parameters passed to C<send> will be returned,	763	In list context, all parameters passed to C<send> will be returned,
490	in scalar context only the first one will be returned.	764	in scalar context only the first one will be returned.
491		765
		766	Note that doing a blocking wait in a callback is not supported by any
		767	event loop, that is, recursive invocation of a blocking C<< ->recv
		768	>> is not allowed, and the C<recv> call will C<croak> if such a
		769	condition is detected. This condition can be slightly loosened by using
		770	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		771	any thread that doesn't run the event loop itself.
		772
492	Not all event models support a blocking wait - some die in that case	773	Not all event models support a blocking wait - some die in that case
493	(programs might want to do that to stay interactive), so I<if you are	774	(programs might want to do that to stay interactive), so I<if you are
494	using this from a module, never require a blocking wait>, but let the	775	using this from a module, never require a blocking wait>. Instead, let the
495	caller decide whether the call will block or not (for example, by coupling	776	caller decide whether the call will block or not (for example, by coupling
496	condition variables with some kind of request results and supporting	777	condition variables with some kind of request results and supporting
497	callbacks so the caller knows that getting the result will not block,	778	callbacks so the caller knows that getting the result will not block,
498	while still supporting blocking waits if the caller so desires).	779	while still supporting blocking waits if the caller so desires).
499		780
500	Another reason I<never> to C<< ->recv >> in a module is that you cannot
501	sensibly have two C<< ->recv >>'s in parallel, as that would require
502	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
503	can supply.
504
505	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
506	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
507	versions and also integrates coroutines into AnyEvent, making blocking
508	C<< ->recv >> calls perfectly safe as long as they are done from another
509	coroutine (one that doesn't run the event loop).
510
511	You can ensure that C<< -recv >> never blocks by setting a callback and	781	You can ensure that C<< -recv >> never blocks by setting a callback and
512	only calling C<< ->recv >> from within that callback (or at a later	782	only calling C<< ->recv >> from within that callback (or at a later
513	time). This will work even when the event loop does not support blocking	783	time). This will work even when the event loop does not support blocking
514	waits otherwise.	784	waits otherwise.
515		785
516	=item $bool = $cv->ready	786	=item $bool = $cv->ready
517		787
518	Returns true when the condition is "true", i.e. whether C<send> or	788	Returns true when the condition is "true", i.e. whether C<send> or
519	C<croak> have been called.	789	C<croak> have been called.
520		790
521	=item $cb = $cv->cb ([new callback])	791	=item $cb = $cv->cb ($cb->($cv))
522		792
523	This is a mutator function that returns the callback set and optionally	793	This is a mutator function that returns the callback set and optionally
524	replaces it before doing so.	794	replaces it before doing so.
525		795
526	The callback will be called when the condition becomes "true", i.e. when	796	The callback will be called when the condition becomes (or already was)
527	C<send> or C<croak> are called. Calling C<recv> inside the callback	797	"true", i.e. when C<send> or C<croak> are called (or were called), with
		798	the only argument being the condition variable itself. Calling C<recv>
528	or at any later time is guaranteed not to block.	799	inside the callback or at any later time is guaranteed not to block.
529		800
530	=back	801	=back
531		802
		803	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		804
		805	The available backend classes are (every class has its own manpage):
		806
		807	=over 4
		808
		809	=item Backends that are autoprobed when no other event loop can be found.
		810
		811	EV is the preferred backend when no other event loop seems to be in
		812	use. If EV is not installed, then AnyEvent will fall back to its own
		813	pure-perl implementation, which is available everywhere as it comes with
		814	AnyEvent itself.
		815
		816	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		817	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		818
		819	=item Backends that are transparently being picked up when they are used.
		820
		821	These will be used when they are currently loaded when the first watcher
		822	is created, in which case it is assumed that the application is using
		823	them. This means that AnyEvent will automatically pick the right backend
		824	when the main program loads an event module before anything starts to
		825	create watchers. Nothing special needs to be done by the main program.
		826
		827	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		828	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		829	AnyEvent::Impl::Tk based on Tk, very broken.
		830	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		831	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		832	AnyEvent::Impl::Irssi used when running within irssi.
		833
		834	=item Backends with special needs.
		835
		836	Qt requires the Qt::Application to be instantiated first, but will
		837	otherwise be picked up automatically. As long as the main program
		838	instantiates the application before any AnyEvent watchers are created,
		839	everything should just work.
		840
		841	AnyEvent::Impl::Qt based on Qt.
		842
		843	Support for IO::Async can only be partial, as it is too broken and
		844	architecturally limited to even support the AnyEvent API. It also
		845	is the only event loop that needs the loop to be set explicitly, so
		846	it can only be used by a main program knowing about AnyEvent. See
		847	L<AnyEvent::Impl::Async> for the gory details.
		848
		849	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		850
		851	=item Event loops that are indirectly supported via other backends.
		852
		853	Some event loops can be supported via other modules:
		854
		855	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		856
		857	B<WxWidgets> has no support for watching file handles. However, you can
		858	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		859	polls 20 times per second, which was considered to be too horrible to even
		860	consider for AnyEvent.
		861
		862	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		863	backend, so it can be supported through POE.
		864
		865	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		866	load L<POE> when detecting them, in the hope that POE will pick them up,
		867	in which case everything will be automatic.
		868
		869	=back
		870
532	=head1 GLOBAL VARIABLES AND FUNCTIONS	871	=head1 GLOBAL VARIABLES AND FUNCTIONS
533		872
		873	These are not normally required to use AnyEvent, but can be useful to
		874	write AnyEvent extension modules.
		875
534	=over 4	876	=over 4
535		877
536	=item $AnyEvent::MODEL	878	=item $AnyEvent::MODEL
537		879
538	Contains C<undef> until the first watcher is being created. Then it	880	Contains C<undef> until the first watcher is being created, before the
		881	backend has been autodetected.
		882
539	contains the event model that is being used, which is the name of the	883	Afterwards it contains the event model that is being used, which is the
540	Perl class implementing the model. This class is usually one of the	884	name of the Perl class implementing the model. This class is usually one
541	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	885	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
542	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	886	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
543		887	will be C<urxvt::anyevent>).
544	The known classes so far are:
545
546	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
547	AnyEvent::Impl::Event based on Event, second best choice.
548	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
549	AnyEvent::Impl::Glib based on Glib, third-best choice.
550	AnyEvent::Impl::Tk based on Tk, very bad choice.
551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
553	AnyEvent::Impl::POE based on POE, not generic enough for full support.
554
555	There is no support for WxWidgets, as WxWidgets has no support for
556	watching file handles. However, you can use WxWidgets through the
557	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
558	second, which was considered to be too horrible to even consider for
559	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
560	it's adaptor.
561
562	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
563	autodetecting them.
564		888
565	=item AnyEvent::detect	889	=item AnyEvent::detect
566		890
567	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	891	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
568	if necessary. You should only call this function right before you would	892	if necessary. You should only call this function right before you would
569	have created an AnyEvent watcher anyway, that is, as late as possible at	893	have created an AnyEvent watcher anyway, that is, as late as possible at
570	runtime.	894	runtime, and not e.g. while initialising of your module.
		895
		896	If you need to do some initialisation before AnyEvent watchers are
		897	created, use C<post_detect>.
571		898
572	=item $guard = AnyEvent::post_detect { BLOCK }	899	=item $guard = AnyEvent::post_detect { BLOCK }
573		900
574	Arranges for the code block to be executed as soon as the event model is	901	Arranges for the code block to be executed as soon as the event model is
575	autodetected (or immediately if this has already happened).	902	autodetected (or immediately if this has already happened).
576		903
		904	The block will be executed I<after> the actual backend has been detected
		905	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		906	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		907	other initialisations - see the sources of L<AnyEvent::Strict> or
		908	L<AnyEvent::AIO> to see how this is used.
		909
		910	The most common usage is to create some global watchers, without forcing
		911	event module detection too early, for example, L<AnyEvent::AIO> creates
		912	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		913	avoid autodetecting the event module at load time.
		914
577	If called in scalar or list context, then it creates and returns an object	915	If called in scalar or list context, then it creates and returns an object
578	that automatically removes the callback again when it is destroyed. See	916	that automatically removes the callback again when it is destroyed (or
		917	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
579	L<Coro::BDB> for a case where this is useful.	918	a case where this is useful.
		919
		920	Example: Create a watcher for the IO::AIO module and store it in
		921	C<$WATCHER>. Only do so after the event loop is initialised, though.
		922
		923	our WATCHER;
		924
		925	my $guard = AnyEvent::post_detect {
		926	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		927	};
		928
		929	# the ||= is important in case post_detect immediately runs the block,
		930	# as to not clobber the newly-created watcher. assigning both watcher and
		931	# post_detect guard to the same variable has the advantage of users being
		932	# able to just C<undef $WATCHER> if the watcher causes them grief.
		933
		934	$WATCHER ||= $guard;
580		935
581	=item @AnyEvent::post_detect	936	=item @AnyEvent::post_detect
582		937
583	If there are any code references in this array (you can C<push> to it	938	If there are any code references in this array (you can C<push> to it
584	before or after loading AnyEvent), then they will called directly after	939	before or after loading AnyEvent), then they will called directly after
585	the event loop has been chosen.	940	the event loop has been chosen.
586		941
587	You should check C<$AnyEvent::MODEL> before adding to this array, though:	942	You should check C<$AnyEvent::MODEL> before adding to this array, though:
588	if it contains a true value then the event loop has already been detected,	943	if it is defined then the event loop has already been detected, and the
589	and the array will be ignored.	944	array will be ignored.
590		945
591	Best use C<AnyEvent::post_detect { BLOCK }> instead.	946	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		947	it,as it takes care of these details.
		948
		949	This variable is mainly useful for modules that can do something useful
		950	when AnyEvent is used and thus want to know when it is initialised, but do
		951	not need to even load it by default. This array provides the means to hook
		952	into AnyEvent passively, without loading it.
592		953
593	=back	954	=back
594		955
595	=head1 WHAT TO DO IN A MODULE	956	=head1 WHAT TO DO IN A MODULE
596		957
…		…
651		1012
652		1013
653	=head1 OTHER MODULES	1014	=head1 OTHER MODULES
654		1015
655	The following is a non-exhaustive list of additional modules that use	1016	The following is a non-exhaustive list of additional modules that use
656	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1017	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
657	in the same program. Some of the modules come with AnyEvent, some are	1018	modules and other event loops in the same program. Some of the modules
658	available via CPAN.	1019	come with AnyEvent, most are available via CPAN.
659		1020
660	=over 4	1021	=over 4
661		1022
662	=item L<AnyEvent::Util>	1023	=item L<AnyEvent::Util>
663		1024
664	Contains various utility functions that replace often-used but blocking	1025	Contains various utility functions that replace often-used but blocking
665	functions such as C<inet_aton> by event-/callback-based versions.	1026	functions such as C<inet_aton> by event-/callback-based versions.
666
667	=item L<AnyEvent::Handle>
668
669	Provide read and write buffers and manages watchers for reads and writes.
670		1027
671	=item L<AnyEvent::Socket>	1028	=item L<AnyEvent::Socket>
672		1029
673	Provides various utility functions for (internet protocol) sockets,	1030	Provides various utility functions for (internet protocol) sockets,
674	addresses and name resolution. Also functions to create non-blocking tcp	1031	addresses and name resolution. Also functions to create non-blocking tcp
675	connections or tcp servers, with IPv6 and SRV record support and more.	1032	connections or tcp servers, with IPv6 and SRV record support and more.
676		1033
		1034	=item L<AnyEvent::Handle>
		1035
		1036	Provide read and write buffers, manages watchers for reads and writes,
		1037	supports raw and formatted I/O, I/O queued and fully transparent and
		1038	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1039
677	=item L<AnyEvent::DNS>	1040	=item L<AnyEvent::DNS>
678		1041
679	Provides rich asynchronous DNS resolver capabilities.	1042	Provides rich asynchronous DNS resolver capabilities.
680		1043
		1044	=item L<AnyEvent::HTTP>
		1045
		1046	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1047	HTTP requests.
		1048
681	=item L<AnyEvent::HTTPD>	1049	=item L<AnyEvent::HTTPD>
682		1050
683	Provides a simple web application server framework.	1051	Provides a simple web application server framework.
684		1052
685	=item L<AnyEvent::FastPing>	1053	=item L<AnyEvent::FastPing>
686		1054
687	The fastest ping in the west.	1055	The fastest ping in the west.
688		1056
		1057	=item L<AnyEvent::DBI>
		1058
		1059	Executes L<DBI> requests asynchronously in a proxy process.
		1060
		1061	=item L<AnyEvent::AIO>
		1062
		1063	Truly asynchronous I/O, should be in the toolbox of every event
		1064	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1065	together.
		1066
		1067	=item L<AnyEvent::BDB>
		1068
		1069	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1070	L<BDB> and AnyEvent together.
		1071
		1072	=item L<AnyEvent::GPSD>
		1073
		1074	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1075
689	=item L<Net::IRC3>	1076	=item L<AnyEvent::IRC>
690		1077
691	AnyEvent based IRC client module family.	1078	AnyEvent based IRC client module family (replacing the older Net::IRC3).
692		1079
693	=item L<Net::XMPP2>	1080	=item L<AnyEvent::XMPP>
694		1081
695	AnyEvent based XMPP (Jabber protocol) module family.	1082	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1083	Net::XMPP2>.
		1084
		1085	=item L<AnyEvent::IGS>
		1086
		1087	A non-blocking interface to the Internet Go Server protocol (used by
		1088	L<App::IGS>).
696		1089
697	=item L<Net::FCP>	1090	=item L<Net::FCP>
698		1091
699	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1092	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
700	of AnyEvent.	1093	of AnyEvent.
…		…
705		1098
706	=item L<Coro>	1099	=item L<Coro>
707		1100
708	Has special support for AnyEvent via L<Coro::AnyEvent>.	1101	Has special support for AnyEvent via L<Coro::AnyEvent>.
709		1102
710	=item L<AnyEvent::AIO>, L<IO::AIO>
711
712	Truly asynchronous I/O, should be in the toolbox of every event
713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714	together.
715
716	=item L<AnyEvent::BDB>, L<BDB>
717
718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719	IO::AIO and AnyEvent together.
720
721	=item L<IO::Lambda>
722
723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724
725	=back	1103	=back
726		1104
727	=cut	1105	=cut
728		1106
729	package AnyEvent;	1107	package AnyEvent;
730		1108
731	no warnings;	1109	# basically a tuned-down version of common::sense
732	use strict;	1110	sub common_sense {
		1111	# from common:.sense 1.0
		1112	${^WARNING_BITS} = "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
		1113	# use strict vars subs
		1114	$^H |= 0x00000600;
		1115	}
733		1116
		1117	BEGIN { AnyEvent::common_sense }
		1118
734	use Carp;	1119	use Carp ();
735		1120
736	our $VERSION = '4.04';	1121	our $VERSION = '5.12';
737	our $MODEL;	1122	our $MODEL;
738		1123
739	our $AUTOLOAD;	1124	our $AUTOLOAD;
740	our @ISA;	1125	our @ISA;
741		1126
742	our @REGISTRY;	1127	our @REGISTRY;
743		1128
744	our $WIN32;	1129	our $WIN32;
745		1130
		1131	our $VERBOSE;
		1132
746	BEGIN {	1133	BEGIN {
747	my $win32 = ! ! ($^O =~ /mswin32/i);	1134	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
748	eval "sub WIN32(){ $win32 }";	1135	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
749	}
750		1136
		1137	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1138	if ${^TAINT};
		1139
751	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1140	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1141
		1142	}
		1143
		1144	our $MAX_SIGNAL_LATENCY = 10;
752		1145
753	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1146	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
754		1147
755	{	1148	{
756	my $idx;	1149	my $idx;
757	$PROTOCOL{$_} = ++$idx	1150	$PROTOCOL{$_} = ++$idx
758	for reverse split /\s*,\s*/,	1151	for reverse split /\s*,\s*/,
759	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1152	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
760	}	1153	}
761		1154
762	sub import {
763	shift;
764	return unless @_;
765
766	my $pkg = caller;
767
768	no strict 'refs';
769
770	for (@_) {
771	*{"$pkg\::WIN32"} = *WIN32 if $_ eq "WIN32";
772	}
773	}
774
775	my @models = (	1155	my @models = (
776	[EV:: => AnyEvent::Impl::EV::],	1156	[EV:: => AnyEvent::Impl::EV:: , 1],
777	[Event:: => AnyEvent::Impl::Event::],
778	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1157	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
779	# everything below here will not be autoprobed	1158	# everything below here will not (normally) be autoprobed
780	# as the pureperl backend should work everywhere	1159	# as the pureperl backend should work everywhere
781	# and is usually faster	1160	# and is usually faster
		1161	[Event:: => AnyEvent::Impl::Event::, 1],
		1162	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1163	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1164	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
782	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1165	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
783	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
784	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
785	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1166	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
786	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1167	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
787	[Wx:: => AnyEvent::Impl::POE::],	1168	[Wx:: => AnyEvent::Impl::POE::],
788	[Prima:: => AnyEvent::Impl::POE::],	1169	[Prima:: => AnyEvent::Impl::POE::],
		1170	# IO::Async is just too broken - we would need workarounds for its
		1171	# byzantine signal and broken child handling, among others.
		1172	# IO::Async is rather hard to detect, as it doesn't have any
		1173	# obvious default class.
		1174	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1176	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1177	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
789	);	1178	);
790		1179
791	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1180	our %method = map +($_ => 1),
		1181	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
792		1182
793	our @post_detect;	1183	our @post_detect;
794		1184
795	sub post_detect(&) {	1185	sub post_detect(&) {
796	my ($cb) = @_;	1186	my ($cb) = @_;
797		1187
798	if ($MODEL) {	1188	if ($MODEL) {
799	$cb->();	1189	$cb->();
800		1190
801	1	1191	undef
802	} else {	1192	} else {
803	push @post_detect, $cb;	1193	push @post_detect, $cb;
804		1194
805	defined wantarray	1195	defined wantarray
806	? bless \$cb, "AnyEvent::Util::PostDetect"	1196	? bless \$cb, "AnyEvent::Util::postdetect"
807	: ()	1197	: ()
808	}	1198	}
809	}	1199	}
810		1200
811	sub AnyEvent::Util::PostDetect::DESTROY {	1201	sub AnyEvent::Util::postdetect::DESTROY {
812	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1202	@post_detect = grep $_ != ${$_[0]}, @post_detect;
813	}	1203	}
814		1204
815	sub detect() {	1205	sub detect() {
816	unless ($MODEL) {	1206	unless ($MODEL) {
817	no strict 'refs';
818	local $SIG{__DIE__};	1207	local $SIG{__DIE__};
819		1208
820	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1209	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
821	my $model = "AnyEvent::Impl::$1";	1210	my $model = "AnyEvent::Impl::$1";
822	if (eval "require $model") {	1211	if (eval "require $model") {
823	$MODEL = $model;	1212	$MODEL = $model;
824	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1213	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
825	} else {	1214	} else {
826	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1215	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
827	}	1216	}
828	}	1217	}
829		1218
830	# check for already loaded models	1219	# check for already loaded models
831	unless ($MODEL) {	1220	unless ($MODEL) {
832	for (@REGISTRY, @models) {	1221	for (@REGISTRY, @models) {
833	my ($package, $model) = @$_;	1222	my ($package, $model) = @$_;
834	if (${"$package\::VERSION"} > 0) {	1223	if (${"$package\::VERSION"} > 0) {
835	if (eval "require $model") {	1224	if (eval "require $model") {
836	$MODEL = $model;	1225	$MODEL = $model;
837	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1226	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
838	last;	1227	last;
839	}	1228	}
840	}	1229	}
841	}	1230	}
842		1231
843	unless ($MODEL) {	1232	unless ($MODEL) {
844	# try to load a model	1233	# try to autoload a model
845
846	for (@REGISTRY, @models) {	1234	for (@REGISTRY, @models) {
847	my ($package, $model) = @$_;	1235	my ($package, $model, $autoload) = @$_;
		1236	if (
		1237	$autoload
848	if (eval "require $package"	1238	and eval "require $package"
849	and ${"$package\::VERSION"} > 0	1239	and ${"$package\::VERSION"} > 0
850	and eval "require $model") {	1240	and eval "require $model"
		1241	) {
851	$MODEL = $model;	1242	$MODEL = $model;
852	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1243	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
853	last;	1244	last;
854	}	1245	}
855	}	1246	}
856		1247
857	$MODEL	1248	$MODEL
858	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1249	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
859	}	1250	}
860	}	1251	}
861		1252
		1253	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1254
862	unshift @ISA, $MODEL;	1255	unshift @ISA, $MODEL;
863	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1256
		1257	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
864		1258
865	(shift @post_detect)->() while @post_detect;	1259	(shift @post_detect)->() while @post_detect;
866	}	1260	}
867		1261
868	$MODEL	1262	$MODEL
…		…
870		1264
871	sub AUTOLOAD {	1265	sub AUTOLOAD {
872	(my $func = $AUTOLOAD) =~ s/.*://;	1266	(my $func = $AUTOLOAD) =~ s/.*://;
873		1267
874	$method{$func}	1268	$method{$func}
875	or croak "$func: not a valid method for AnyEvent objects";	1269	or Carp::croak "$func: not a valid method for AnyEvent objects";
876		1270
877	detect unless $MODEL;	1271	detect unless $MODEL;
878		1272
879	my $class = shift;	1273	my $class = shift;
880	$class->$func (@_);	1274	$class->$func (@_);
881	}	1275	}
882		1276
		1277	# utility function to dup a filehandle. this is used by many backends
		1278	# to support binding more than one watcher per filehandle (they usually
		1279	# allow only one watcher per fd, so we dup it to get a different one).
		1280	sub _dupfh($$;$$) {
		1281	my ($poll, $fh, $r, $w) = @_;
		1282
		1283	# cygwin requires the fh mode to be matching, unix doesn't
		1284	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1285
		1286	open my $fh2, $mode, $fh
		1287	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1288
		1289	# we assume CLOEXEC is already set by perl in all important cases
		1290
		1291	($fh2, $rw)
		1292	}
		1293
		1294	=head1 SIMPLIFIED AE API
		1295
		1296	Starting with version 5.0, AnyEvent officially supports a second, much
		1297	simpler, API that is designed to reduce the calling, typing and memory
		1298	overhead.
		1299
		1300	See the L<AE> manpage for details.
		1301
		1302	=cut
		1303
		1304	package AE;
		1305
		1306	our $VERSION = $AnyEvent::VERSION;
		1307
		1308	sub io($$$) {
		1309	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1310	}
		1311
		1312	sub timer($$$) {
		1313	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1314	}
		1315
		1316	sub signal($$) {
		1317	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1318	}
		1319
		1320	sub child($$) {
		1321	AnyEvent->child (pid => $_[0], cb => $_[1])
		1322	}
		1323
		1324	sub idle($) {
		1325	AnyEvent->idle (cb => $_[0])
		1326	}
		1327
		1328	sub cv(;&) {
		1329	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1330	}
		1331
		1332	sub now() {
		1333	AnyEvent->now
		1334	}
		1335
		1336	sub now_update() {
		1337	AnyEvent->now_update
		1338	}
		1339
		1340	sub time() {
		1341	AnyEvent->time
		1342	}
		1343
883	package AnyEvent::Base;	1344	package AnyEvent::Base;
884		1345
		1346	# default implementations for many methods
		1347
		1348	sub _time() {
		1349	# probe for availability of Time::HiRes
		1350	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1351	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1352	*_time = \&Time::HiRes::time;
		1353	# if (eval "use POSIX (); (POSIX::times())...
		1354	} else {
		1355	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1356	*_time = sub { time }; # epic fail
		1357	}
		1358
		1359	&_time
		1360	}
		1361
		1362	sub time { _time }
		1363	sub now { _time }
		1364	sub now_update { }
		1365
885	# default implementation for ->condvar	1366	# default implementation for ->condvar
886		1367
887	sub condvar {	1368	sub condvar {
888	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1369	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
889	}	1370	}
890		1371
891	# default implementation for ->signal	1372	# default implementation for ->signal
892		1373
893	our %SIG_CB;	1374	our $HAVE_ASYNC_INTERRUPT;
		1375
		1376	sub _have_async_interrupt() {
		1377	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1378	&& eval "use Async::Interrupt 1.02 (); 1")
		1379	unless defined $HAVE_ASYNC_INTERRUPT;
		1380
		1381	$HAVE_ASYNC_INTERRUPT
		1382	}
		1383
		1384	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1385	our (%SIG_ASY, %SIG_ASY_W);
		1386	our ($SIG_COUNT, $SIG_TW);
		1387
		1388	sub _signal_exec {
		1389	$HAVE_ASYNC_INTERRUPT
		1390	? $SIGPIPE_R->drain
		1391	: sysread $SIGPIPE_R, my $dummy, 9;
		1392
		1393	while (%SIG_EV) {
		1394	for (keys %SIG_EV) {
		1395	delete $SIG_EV{$_};
		1396	$_->() for values %{ $SIG_CB{$_} || {} };
		1397	}
		1398	}
		1399	}
		1400
		1401	# install a dummy wakeup watcher to reduce signal catching latency
		1402	sub _sig_add() {
		1403	unless ($SIG_COUNT++) {
		1404	# try to align timer on a full-second boundary, if possible
		1405	my $NOW = AE::now;
		1406
		1407	$SIG_TW = AE::timer
		1408	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1409	$MAX_SIGNAL_LATENCY,
		1410	sub { } # just for the PERL_ASYNC_CHECK
		1411	;
		1412	}
		1413	}
		1414
		1415	sub _sig_del {
		1416	undef $SIG_TW
		1417	unless --$SIG_COUNT;
		1418	}
		1419
		1420	our $_sig_name_init; $_sig_name_init = sub {
		1421	eval q{ # poor man's autoloading
		1422	undef $_sig_name_init;
		1423
		1424	if (_have_async_interrupt) {
		1425	*sig2num = \&Async::Interrupt::sig2num;
		1426	*sig2name = \&Async::Interrupt::sig2name;
		1427	} else {
		1428	require Config;
		1429
		1430	my %signame2num;
		1431	@signame2num{ split ' ', $Config::Config{sig_name} }
		1432	= split ' ', $Config::Config{sig_num};
		1433
		1434	my @signum2name;
		1435	@signum2name[values %signame2num] = keys %signame2num;
		1436
		1437	*sig2num = sub($) {
		1438	$_[0] > 0 ? shift : $signame2num{+shift}
		1439	};
		1440	*sig2name = sub ($) {
		1441	$_[0] > 0 ? $signum2name[+shift] : shift
		1442	};
		1443	}
		1444	};
		1445	die if $@;
		1446	};
		1447
		1448	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1449	sub sig2name($) { &$_sig_name_init; &sig2name }
894		1450
895	sub signal {	1451	sub signal {
		1452	eval q{ # poor man's autoloading {}
		1453	# probe for availability of Async::Interrupt
		1454	if (_have_async_interrupt) {
		1455	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1456
		1457	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1458	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1459
		1460	} else {
		1461	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1462
		1463	require Fcntl;
		1464
		1465	if (AnyEvent::WIN32) {
		1466	require AnyEvent::Util;
		1467
		1468	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1469	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1470	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1471	} else {
		1472	pipe $SIGPIPE_R, $SIGPIPE_W;
		1473	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1474	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1475
		1476	# not strictly required, as $^F is normally 2, but let's make sure...
		1477	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1478	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1479	}
		1480
		1481	$SIGPIPE_R
		1482	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1483
		1484	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1485	}
		1486
		1487	*signal = sub {
896	my (undef, %arg) = @_;	1488	my (undef, %arg) = @_;
897		1489
898	my $signal = uc $arg{signal}	1490	my $signal = uc $arg{signal}
899	or Carp::croak "required option 'signal' is missing";	1491	or Carp::croak "required option 'signal' is missing";
900		1492
		1493	if ($HAVE_ASYNC_INTERRUPT) {
		1494	# async::interrupt
		1495
		1496	$signal = sig2num $signal;
901	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1497	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1498
		1499	$SIG_ASY{$signal} ||= new Async::Interrupt
		1500	cb => sub { undef $SIG_EV{$signal} },
		1501	signal => $signal,
		1502	pipe => [$SIGPIPE_R->filenos],
		1503	pipe_autodrain => 0,
		1504	;
		1505
		1506	} else {
		1507	# pure perl
		1508
		1509	# AE::Util has been loaded in signal
		1510	$signal = sig2name $signal;
		1511	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1512
902	$SIG{$signal} ||= sub {	1513	$SIG{$signal} ||= sub {
903	$_->() for values %{ $SIG_CB{$signal} || {} };	1514	local $!;
		1515	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1516	undef $SIG_EV{$signal};
		1517	};
		1518
		1519	# can't do signal processing without introducing races in pure perl,
		1520	# so limit the signal latency.
		1521	_sig_add;
		1522	}
		1523
		1524	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1525	};
		1526
		1527	*AnyEvent::Base::signal::DESTROY = sub {
		1528	my ($signal, $cb) = @{$_[0]};
		1529
		1530	_sig_del;
		1531
		1532	delete $SIG_CB{$signal}{$cb};
		1533
		1534	$HAVE_ASYNC_INTERRUPT
		1535	? delete $SIG_ASY{$signal}
		1536	: # delete doesn't work with older perls - they then
		1537	# print weird messages, or just unconditionally exit
		1538	# instead of getting the default action.
		1539	undef $SIG{$signal}
		1540	unless keys %{ $SIG_CB{$signal} };
		1541	};
904	};	1542	};
905		1543	die if $@;
906	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1544	&signal
907	}
908
909	sub AnyEvent::Base::Signal::DESTROY {
910	my ($signal, $cb) = @{$_[0]};
911
912	delete $SIG_CB{$signal}{$cb};
913
914	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
915	}	1545	}
916		1546
917	# default implementation for ->child	1547	# default implementation for ->child
918		1548
919	our %PID_CB;	1549	our %PID_CB;
920	our $CHLD_W;	1550	our $CHLD_W;
921	our $CHLD_DELAY_W;	1551	our $CHLD_DELAY_W;
922	our $PID_IDLE;
923	our $WNOHANG;	1552	our $WNOHANG;
924		1553
925	sub _child_wait {	1554	sub _emit_childstatus($$) {
926	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1555	my (undef, $rpid, $rstatus) = @_;
		1556
		1557	$_->($rpid, $rstatus)
927	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1558	for values %{ $PID_CB{$rpid} || {} },
928	(values %{ $PID_CB{0} || {} });	1559	values %{ $PID_CB{0} || {} };
929	}
930
931	undef $PID_IDLE;
932	}	1560	}
933		1561
934	sub _sigchld {	1562	sub _sigchld {
935	# make sure we deliver these changes "synchronous" with the event loop.	1563	my $pid;
936	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1564
937	undef $CHLD_DELAY_W;	1565	AnyEvent->_emit_childstatus ($pid, $?)
938	&_child_wait;	1566	while ($pid = waitpid -1, $WNOHANG) > 0;
939	});
940	}	1567	}
941		1568
942	sub child {	1569	sub child {
943	my (undef, %arg) = @_;	1570	my (undef, %arg) = @_;
944		1571
945	defined (my $pid = $arg{pid} + 0)	1572	defined (my $pid = $arg{pid} + 0)
946	or Carp::croak "required option 'pid' is missing";	1573	or Carp::croak "required option 'pid' is missing";
947		1574
948	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1575	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
949		1576
950	unless ($WNOHANG) {	1577	# WNOHANG is almost cetrainly 1 everywhere
		1578	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1579	? 1
951	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1580	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
952	}
953		1581
954	unless ($CHLD_W) {	1582	unless ($CHLD_W) {
955	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1583	$CHLD_W = AE::signal CHLD => \&_sigchld;
956	# child could be a zombie already, so make at least one round	1584	# child could be a zombie already, so make at least one round
957	&_sigchld;	1585	&_sigchld;
958	}	1586	}
959		1587
960	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1588	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
961	}	1589	}
962		1590
963	sub AnyEvent::Base::Child::DESTROY {	1591	sub AnyEvent::Base::child::DESTROY {
964	my ($pid, $cb) = @{$_[0]};	1592	my ($pid, $cb) = @{$_[0]};
965		1593
966	delete $PID_CB{$pid}{$cb};	1594	delete $PID_CB{$pid}{$cb};
967	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1595	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
968		1596
969	undef $CHLD_W unless keys %PID_CB;	1597	undef $CHLD_W unless keys %PID_CB;
970	}	1598	}
971		1599
		1600	# idle emulation is done by simply using a timer, regardless
		1601	# of whether the process is idle or not, and not letting
		1602	# the callback use more than 50% of the time.
		1603	sub idle {
		1604	my (undef, %arg) = @_;
		1605
		1606	my ($cb, $w, $rcb) = $arg{cb};
		1607
		1608	$rcb = sub {
		1609	if ($cb) {
		1610	$w = _time;
		1611	&$cb;
		1612	$w = _time - $w;
		1613
		1614	# never use more then 50% of the time for the idle watcher,
		1615	# within some limits
		1616	$w = 0.0001 if $w < 0.0001;
		1617	$w = 5 if $w > 5;
		1618
		1619	$w = AE::timer $w, 0, $rcb;
		1620	} else {
		1621	# clean up...
		1622	undef $w;
		1623	undef $rcb;
		1624	}
		1625	};
		1626
		1627	$w = AE::timer 0.05, 0, $rcb;
		1628
		1629	bless \\$cb, "AnyEvent::Base::idle"
		1630	}
		1631
		1632	sub AnyEvent::Base::idle::DESTROY {
		1633	undef $${$_[0]};
		1634	}
		1635
972	package AnyEvent::CondVar;	1636	package AnyEvent::CondVar;
973		1637
974	our @ISA = AnyEvent::CondVar::Base::;	1638	our @ISA = AnyEvent::CondVar::Base::;
975		1639
976	package AnyEvent::CondVar::Base;	1640	package AnyEvent::CondVar::Base;
977		1641
978	use overload	1642	#use overload
979	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1643	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
980	fallback => 1;	1644	# fallback => 1;
		1645
		1646	# save 300+ kilobytes by dirtily hardcoding overloading
		1647	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1648	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1649	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1650	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1651
		1652	our $WAITING;
981		1653
982	sub _send {	1654	sub _send {
983	# nop	1655	# nop
984	}	1656	}
985		1657
…		…
998	sub ready {	1670	sub ready {
999	$_[0]{_ae_sent}	1671	$_[0]{_ae_sent}
1000	}	1672	}
1001		1673
1002	sub _wait {	1674	sub _wait {
		1675	$WAITING
		1676	and !$_[0]{_ae_sent}
		1677	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1678
		1679	local $WAITING = 1;
1003	AnyEvent->one_event while !$_[0]{_ae_sent};	1680	AnyEvent->one_event while !$_[0]{_ae_sent};
1004	}	1681	}
1005		1682
1006	sub recv {	1683	sub recv {
1007	$_[0]->_wait;	1684	$_[0]->_wait;
…		…
1009	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1686	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1010	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1687	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1011	}	1688	}
1012		1689
1013	sub cb {	1690	sub cb {
1014	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1691	my $cv = shift;
		1692
		1693	@_
		1694	and $cv->{_ae_cb} = shift
		1695	and $cv->{_ae_sent}
		1696	and (delete $cv->{_ae_cb})->($cv);
		1697
1015	$_[0]{_ae_cb}	1698	$cv->{_ae_cb}
1016	}	1699	}
1017		1700
1018	sub begin {	1701	sub begin {
1019	++$_[0]{_ae_counter};	1702	++$_[0]{_ae_counter};
1020	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1703	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1026	}	1709	}
1027		1710
1028	# undocumented/compatibility with pre-3.4	1711	# undocumented/compatibility with pre-3.4
1029	*broadcast = \&send;	1712	*broadcast = \&send;
1030	*wait = \&_wait;	1713	*wait = \&_wait;
		1714
		1715	=head1 ERROR AND EXCEPTION HANDLING
		1716
		1717	In general, AnyEvent does not do any error handling - it relies on the
		1718	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1719	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1720	checking of all AnyEvent methods, however, which is highly useful during
		1721	development.
		1722
		1723	As for exception handling (i.e. runtime errors and exceptions thrown while
		1724	executing a callback), this is not only highly event-loop specific, but
		1725	also not in any way wrapped by this module, as this is the job of the main
		1726	program.
		1727
		1728	The pure perl event loop simply re-throws the exception (usually
		1729	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1730	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1731	so on.
		1732
		1733	=head1 ENVIRONMENT VARIABLES
		1734
		1735	The following environment variables are used by this module or its
		1736	submodules.
		1737
		1738	Note that AnyEvent will remove I<all> environment variables starting with
		1739	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1740	enabled.
		1741
		1742	=over 4
		1743
		1744	=item C<PERL_ANYEVENT_VERBOSE>
		1745
		1746	By default, AnyEvent will be completely silent except in fatal
		1747	conditions. You can set this environment variable to make AnyEvent more
		1748	talkative.
		1749
		1750	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1751	conditions, such as not being able to load the event model specified by
		1752	C<PERL_ANYEVENT_MODEL>.
		1753
		1754	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1755	model it chooses.
		1756
		1757	When set to C<8> or higher, then AnyEvent will report extra information on
		1758	which optional modules it loads and how it implements certain features.
		1759
		1760	=item C<PERL_ANYEVENT_STRICT>
		1761
		1762	AnyEvent does not do much argument checking by default, as thorough
		1763	argument checking is very costly. Setting this variable to a true value
		1764	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1765	check the arguments passed to most method calls. If it finds any problems,
		1766	it will croak.
		1767
		1768	In other words, enables "strict" mode.
		1769
		1770	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1771	>>, it is definitely recommended to keep it off in production. Keeping
		1772	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1773	can be very useful, however.
		1774
		1775	=item C<PERL_ANYEVENT_MODEL>
		1776
		1777	This can be used to specify the event model to be used by AnyEvent, before
		1778	auto detection and -probing kicks in. It must be a string consisting
		1779	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1780	and the resulting module name is loaded and if the load was successful,
		1781	used as event model. If it fails to load AnyEvent will proceed with
		1782	auto detection and -probing.
		1783
		1784	This functionality might change in future versions.
		1785
		1786	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1787	could start your program like this:
		1788
		1789	PERL_ANYEVENT_MODEL=Perl perl ...
		1790
		1791	=item C<PERL_ANYEVENT_PROTOCOLS>
		1792
		1793	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1794	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1795	of auto probing).
		1796
		1797	Must be set to a comma-separated list of protocols or address families,
		1798	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1799	used, and preference will be given to protocols mentioned earlier in the
		1800	list.
		1801
		1802	This variable can effectively be used for denial-of-service attacks
		1803	against local programs (e.g. when setuid), although the impact is likely
		1804	small, as the program has to handle conenction and other failures anyways.
		1805
		1806	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1807	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1808	- only support IPv4, never try to resolve or contact IPv6
		1809	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1810	IPv6, but prefer IPv6 over IPv4.
		1811
		1812	=item C<PERL_ANYEVENT_EDNS0>
		1813
		1814	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1815	for DNS. This extension is generally useful to reduce DNS traffic, but
		1816	some (broken) firewalls drop such DNS packets, which is why it is off by
		1817	default.
		1818
		1819	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1820	EDNS0 in its DNS requests.
		1821
		1822	=item C<PERL_ANYEVENT_MAX_FORKS>
		1823
		1824	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1825	will create in parallel.
		1826
		1827	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1828
		1829	The default value for the C<max_outstanding> parameter for the default DNS
		1830	resolver - this is the maximum number of parallel DNS requests that are
		1831	sent to the DNS server.
		1832
		1833	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1834
		1835	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1836	configuration) in the default resolver. When set to the empty string, no
		1837	default config will be used.
		1838
		1839	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1840
		1841	When neither C<ca_file> nor C<ca_path> was specified during
		1842	L<AnyEvent::TLS> context creation, and either of these environment
		1843	variables exist, they will be used to specify CA certificate locations
		1844	instead of a system-dependent default.
		1845
		1846	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1847
		1848	When these are set to C<1>, then the respective modules are not
		1849	loaded. Mostly good for testing AnyEvent itself.
		1850
		1851	=back
1031		1852
1032	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1853	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1033		1854
1034	This is an advanced topic that you do not normally need to use AnyEvent in	1855	This is an advanced topic that you do not normally need to use AnyEvent in
1035	a module. This section is only of use to event loop authors who want to	1856	a module. This section is only of use to event loop authors who want to
…		…
1069		1890
1070	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1891	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1071	condition variables: code blocking while waiting for a condition will	1892	condition variables: code blocking while waiting for a condition will
1072	C<die>. This still works with most modules/usages, and blocking calls must	1893	C<die>. This still works with most modules/usages, and blocking calls must
1073	not be done in an interactive application, so it makes sense.	1894	not be done in an interactive application, so it makes sense.
1074
1075	=head1 ENVIRONMENT VARIABLES
1076
1077	The following environment variables are used by this module:
1078
1079	=over 4
1080
1081	=item C<PERL_ANYEVENT_VERBOSE>
1082
1083	By default, AnyEvent will be completely silent except in fatal
1084	conditions. You can set this environment variable to make AnyEvent more
1085	talkative.
1086
1087	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1088	conditions, such as not being able to load the event model specified by
1089	C<PERL_ANYEVENT_MODEL>.
1090
1091	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1092	model it chooses.
1093
1094	=item C<PERL_ANYEVENT_MODEL>
1095
1096	This can be used to specify the event model to be used by AnyEvent, before
1097	auto detection and -probing kicks in. It must be a string consisting
1098	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1099	and the resulting module name is loaded and if the load was successful,
1100	used as event model. If it fails to load AnyEvent will proceed with
1101	auto detection and -probing.
1102
1103	This functionality might change in future versions.
1104
1105	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1106	could start your program like this:
1107
1108	PERL_ANYEVENT_MODEL=Perl perl ...
1109
1110	=item C<PERL_ANYEVENT_PROTOCOLS>
1111
1112	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1113	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1114	of auto probing).
1115
1116	Must be set to a comma-separated list of protocols or address families,
1117	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1118	used, and preference will be given to protocols mentioned earlier in the
1119	list.
1120
1121	This variable can effectively be used for denial-of-service attacks
1122	against local programs (e.g. when setuid), although the impact is likely
1123	small, as the program has to handle connection errors already-
1124
1125	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1126	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1127	- only support IPv4, never try to resolve or contact IPv6
1128	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1129	IPv6, but prefer IPv6 over IPv4.
1130
1131	=item C<PERL_ANYEVENT_EDNS0>
1132
1133	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1134	for DNS. This extension is generally useful to reduce DNS traffic, but
1135	some (broken) firewalls drop such DNS packets, which is why it is off by
1136	default.
1137
1138	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1139	EDNS0 in its DNS requests.
1140
1141	=back
1142		1895
1143	=head1 EXAMPLE PROGRAM	1896	=head1 EXAMPLE PROGRAM
1144		1897
1145	The following program uses an I/O watcher to read data from STDIN, a timer	1898	The following program uses an I/O watcher to read data from STDIN, a timer
1146	to display a message once per second, and a condition variable to quit the	1899	to display a message once per second, and a condition variable to quit the
…		…
1159	warn "read: $input\n"; # output what has been read	1912	warn "read: $input\n"; # output what has been read
1160	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1913	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1161	},	1914	},
1162	);	1915	);
1163		1916
1164	my $time_watcher; # can only be used once
1165
1166	sub new_timer {
1167	$timer = AnyEvent->timer (after => 1, cb => sub {	1917	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1168	warn "timeout\n"; # print 'timeout' about every second	1918	warn "timeout\n"; # print 'timeout' at most every second
1169	&new_timer; # and restart the time
1170	});	1919	});
1171	}
1172
1173	new_timer; # create first timer
1174		1920
1175	$cv->recv; # wait until user enters /^q/i	1921	$cv->recv; # wait until user enters /^q/i
1176		1922
1177	=head1 REAL-WORLD EXAMPLE	1923	=head1 REAL-WORLD EXAMPLE
1178		1924
…		…
1309	through AnyEvent. The benchmark creates a lot of timers (with a zero	2055	through AnyEvent. The benchmark creates a lot of timers (with a zero
1310	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2056	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1311	which it is), lets them fire exactly once and destroys them again.	2057	which it is), lets them fire exactly once and destroys them again.
1312		2058
1313	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2059	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1314	distribution.	2060	distribution. It uses the L<AE> interface, which makes a real difference
		2061	for the EV and Perl backends only.
1315		2062
1316	=head3 Explanation of the columns	2063	=head3 Explanation of the columns
1317		2064
1318	I<watcher> is the number of event watchers created/destroyed. Since	2065	I<watcher> is the number of event watchers created/destroyed. Since
1319	different event models feature vastly different performances, each event	2066	different event models feature vastly different performances, each event
…		…
1340	watcher.	2087	watcher.
1341		2088
1342	=head3 Results	2089	=head3 Results
1343		2090
1344	name watchers bytes create invoke destroy comment	2091	name watchers bytes create invoke destroy comment
1345	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2092	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1346	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2093	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1347	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2094	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1348	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2095	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1349	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2096	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1350	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2097	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2098	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2099	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1351	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2100	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1352	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2101	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1353	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2102	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1354	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2103	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1355		2104
1356	=head3 Discussion	2105	=head3 Discussion
1357		2106
1358	The benchmark does I<not> measure scalability of the event loop very	2107	The benchmark does I<not> measure scalability of the event loop very
1359	well. For example, a select-based event loop (such as the pure perl one)	2108	well. For example, a select-based event loop (such as the pure perl one)
…		…
1371	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2120	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1372	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2121	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1373	cycles with POE.	2122	cycles with POE.
1374		2123
1375	C<EV> is the sole leader regarding speed and memory use, which are both	2124	C<EV> is the sole leader regarding speed and memory use, which are both
1376	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2125	maximal/minimal, respectively. When using the L<AE> API there is zero
		2126	overhead (when going through the AnyEvent API create is about 5-6 times
		2127	slower, with other times being equal, so still uses far less memory than
1377	far less memory than any other event loop and is still faster than Event	2128	any other event loop and is still faster than Event natively).
1378	natively.
1379		2129
1380	The pure perl implementation is hit in a few sweet spots (both the	2130	The pure perl implementation is hit in a few sweet spots (both the
1381	constant timeout and the use of a single fd hit optimisations in the perl	2131	constant timeout and the use of a single fd hit optimisations in the perl
1382	interpreter and the backend itself). Nevertheless this shows that it	2132	interpreter and the backend itself). Nevertheless this shows that it
1383	adds very little overhead in itself. Like any select-based backend its	2133	adds very little overhead in itself. Like any select-based backend its
1384	performance becomes really bad with lots of file descriptors (and few of	2134	performance becomes really bad with lots of file descriptors (and few of
1385	them active), of course, but this was not subject of this benchmark.	2135	them active), of course, but this was not subject of this benchmark.
1386		2136
1387	The C<Event> module has a relatively high setup and callback invocation	2137	The C<Event> module has a relatively high setup and callback invocation
1388	cost, but overall scores in on the third place.	2138	cost, but overall scores in on the third place.
		2139
		2140	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2141	when using its pure perl backend.
1389		2142
1390	C<Glib>'s memory usage is quite a bit higher, but it features a	2143	C<Glib>'s memory usage is quite a bit higher, but it features a
1391	faster callback invocation and overall ends up in the same class as	2144	faster callback invocation and overall ends up in the same class as
1392	C<Event>. However, Glib scales extremely badly, doubling the number of	2145	C<Event>. However, Glib scales extremely badly, doubling the number of
1393	watchers increases the processing time by more than a factor of four,	2146	watchers increases the processing time by more than a factor of four,
…		…
1454	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2207	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1455	(1%) are active. This mirrors the activity of large servers with many	2208	(1%) are active. This mirrors the activity of large servers with many
1456	connections, most of which are idle at any one point in time.	2209	connections, most of which are idle at any one point in time.
1457		2210
1458	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2211	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1459	distribution.	2212	distribution. It uses the L<AE> interface, which makes a real difference
		2213	for the EV and Perl backends only.
1460		2214
1461	=head3 Explanation of the columns	2215	=head3 Explanation of the columns
1462		2216
1463	I<sockets> is the number of sockets, and twice the number of "servers" (as	2217	I<sockets> is the number of sockets, and twice the number of "servers" (as
1464	each server has a read and write socket end).	2218	each server has a read and write socket end).
…		…
1471	it to another server. This includes deleting the old timeout and creating	2225	it to another server. This includes deleting the old timeout and creating
1472	a new one that moves the timeout into the future.	2226	a new one that moves the timeout into the future.
1473		2227
1474	=head3 Results	2228	=head3 Results
1475		2229
1476	name sockets create request	2230	name sockets create request
1477	EV 20000 69.01 11.16	2231	EV 20000 62.66 7.99
1478	Perl 20000 73.32 35.87	2232	Perl 20000 68.32 32.64
1479	Event 20000 212.62 257.32	2233	IOAsync 20000 174.06 101.15 epoll
1480	Glib 20000 651.16 1896.30	2234	IOAsync 20000 174.67 610.84 poll
		2235	Event 20000 202.69 242.91
		2236	Glib 20000 557.01 1689.52
1481	POE 20000 349.67 12317.24 uses POE::Loop::Event	2237	POE 20000 341.54 12086.32 uses POE::Loop::Event
1482		2238
1483	=head3 Discussion	2239	=head3 Discussion
1484		2240
1485	This benchmark I<does> measure scalability and overall performance of the	2241	This benchmark I<does> measure scalability and overall performance of the
1486	particular event loop.	2242	particular event loop.
…		…
1488	EV is again fastest. Since it is using epoll on my system, the setup time	2244	EV is again fastest. Since it is using epoll on my system, the setup time
1489	is relatively high, though.	2245	is relatively high, though.
1490		2246
1491	Perl surprisingly comes second. It is much faster than the C-based event	2247	Perl surprisingly comes second. It is much faster than the C-based event
1492	loops Event and Glib.	2248	loops Event and Glib.
		2249
		2250	IO::Async performs very well when using its epoll backend, and still quite
		2251	good compared to Glib when using its pure perl backend.
1493		2252
1494	Event suffers from high setup time as well (look at its code and you will	2253	Event suffers from high setup time as well (look at its code and you will
1495	understand why). Callback invocation also has a high overhead compared to	2254	understand why). Callback invocation also has a high overhead compared to
1496	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2255	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1497	uses select or poll in basically all documented configurations.	2256	uses select or poll in basically all documented configurations.
…		…
1560	=item * C-based event loops perform very well with small number of	2319	=item * C-based event loops perform very well with small number of
1561	watchers, as the management overhead dominates.	2320	watchers, as the management overhead dominates.
1562		2321
1563	=back	2322	=back
1564		2323
		2324	=head2 THE IO::Lambda BENCHMARK
		2325
		2326	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2327	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2328	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2329	shouldn't come as a surprise to anybody). As such, the benchmark is
		2330	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2331	very optimal. But how would AnyEvent compare when used without the extra
		2332	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2333
		2334	The benchmark itself creates an echo-server, and then, for 500 times,
		2335	connects to the echo server, sends a line, waits for the reply, and then
		2336	creates the next connection. This is a rather bad benchmark, as it doesn't
		2337	test the efficiency of the framework or much non-blocking I/O, but it is a
		2338	benchmark nevertheless.
		2339
		2340	name runtime
		2341	Lambda/select 0.330 sec
		2342	+ optimized 0.122 sec
		2343	Lambda/AnyEvent 0.327 sec
		2344	+ optimized 0.138 sec
		2345	Raw sockets/select 0.077 sec
		2346	POE/select, components 0.662 sec
		2347	POE/select, raw sockets 0.226 sec
		2348	POE/select, optimized 0.404 sec
		2349
		2350	AnyEvent/select/nb 0.085 sec
		2351	AnyEvent/EV/nb 0.068 sec
		2352	+state machine 0.134 sec
		2353
		2354	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2355	benchmarks actually make blocking connects and use 100% blocking I/O,
		2356	defeating the purpose of an event-based solution. All of the newly
		2357	written AnyEvent benchmarks use 100% non-blocking connects (using
		2358	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2359	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2360	generally require a lot more bookkeeping and event handling than blocking
		2361	connects (which involve a single syscall only).
		2362
		2363	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2364	offers similar expressive power as POE and IO::Lambda, using conventional
		2365	Perl syntax. This means that both the echo server and the client are 100%
		2366	non-blocking, further placing it at a disadvantage.
		2367
		2368	As you can see, the AnyEvent + EV combination even beats the
		2369	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2370	backend easily beats IO::Lambda and POE.
		2371
		2372	And even the 100% non-blocking version written using the high-level (and
		2373	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2374	higher level ("unoptimised") abstractions by a large margin, even though
		2375	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2376
		2377	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2378	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2379	part of the IO::Lambda distribution and were used without any changes.
		2380
		2381
		2382	=head1 SIGNALS
		2383
		2384	AnyEvent currently installs handlers for these signals:
		2385
		2386	=over 4
		2387
		2388	=item SIGCHLD
		2389
		2390	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2391	emulation for event loops that do not support them natively. Also, some
		2392	event loops install a similar handler.
		2393
		2394	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2395	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2396
		2397	=item SIGPIPE
		2398
		2399	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2400	when AnyEvent gets loaded.
		2401
		2402	The rationale for this is that AnyEvent users usually do not really depend
		2403	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2404	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2405	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2406	some random socket.
		2407
		2408	The rationale for installing a no-op handler as opposed to ignoring it is
		2409	that this way, the handler will be restored to defaults on exec.
		2410
		2411	Feel free to install your own handler, or reset it to defaults.
		2412
		2413	=back
		2414
		2415	=cut
		2416
		2417	undef $SIG{CHLD}
		2418	if $SIG{CHLD} eq 'IGNORE';
		2419
		2420	$SIG{PIPE} = sub { }
		2421	unless defined $SIG{PIPE};
		2422
		2423	=head1 RECOMMENDED/OPTIONAL MODULES
		2424
		2425	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2426	it's built-in modules) are required to use it.
		2427
		2428	That does not mean that AnyEvent won't take advantage of some additional
		2429	modules if they are installed.
		2430
		2431	This section epxlains which additional modules will be used, and how they
		2432	affect AnyEvent's operetion.
		2433
		2434	=over 4
		2435
		2436	=item L<Async::Interrupt>
		2437
		2438	This slightly arcane module is used to implement fast signal handling: To
		2439	my knowledge, there is no way to do completely race-free and quick
		2440	signal handling in pure perl. To ensure that signals still get
		2441	delivered, AnyEvent will start an interval timer to wake up perl (and
		2442	catch the signals) with some delay (default is 10 seconds, look for
		2443	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2444
		2445	If this module is available, then it will be used to implement signal
		2446	catching, which means that signals will not be delayed, and the event loop
		2447	will not be interrupted regularly, which is more efficient (And good for
		2448	battery life on laptops).
		2449
		2450	This affects not just the pure-perl event loop, but also other event loops
		2451	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2452
		2453	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2454	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2455	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2456	does nothing for those backends.
		2457
		2458	=item L<EV>
		2459
		2460	This module isn't really "optional", as it is simply one of the backend
		2461	event loops that AnyEvent can use. However, it is simply the best event
		2462	loop available in terms of features, speed and stability: It supports
		2463	the AnyEvent API optimally, implements all the watcher types in XS, does
		2464	automatic timer adjustments even when no monotonic clock is available,
		2465	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2466	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2467	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2468
		2469	=item L<Guard>
		2470
		2471	The guard module, when used, will be used to implement
		2472	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2473	lot less memory), but otherwise doesn't affect guard operation much. It is
		2474	purely used for performance.
		2475
		2476	=item L<JSON> and L<JSON::XS>
		2477
		2478	This module is required when you want to read or write JSON data via
		2479	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2480	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2481
		2482	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2483	installed.
		2484
		2485	=item L<Net::SSLeay>
		2486
		2487	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2488	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2489	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2490
		2491	=item L<Time::HiRes>
		2492
		2493	This module is part of perl since release 5.008. It will be used when the
		2494	chosen event library does not come with a timing source on it's own. The
		2495	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2496	try to use a monotonic clock for timing stability.
		2497
		2498	=back
		2499
1565		2500
1566	=head1 FORK	2501	=head1 FORK
1567		2502
1568	Most event libraries are not fork-safe. The ones who are usually are	2503	Most event libraries are not fork-safe. The ones who are usually are
1569	because they rely on inefficient but fork-safe C<select> or C<poll>	2504	because they rely on inefficient but fork-safe C<select> or C<poll>
1570	calls. Only L<EV> is fully fork-aware.	2505	calls. Only L<EV> is fully fork-aware.
1571		2506
1572	If you have to fork, you must either do so I<before> creating your first	2507	If you have to fork, you must either do so I<before> creating your first
1573	watcher OR you must not use AnyEvent at all in the child.	2508	watcher OR you must not use AnyEvent at all in the child OR you must do
		2509	something completely out of the scope of AnyEvent.
1574		2510
1575		2511
1576	=head1 SECURITY CONSIDERATIONS	2512	=head1 SECURITY CONSIDERATIONS
1577		2513
1578	AnyEvent can be forced to load any event model via	2514	AnyEvent can be forced to load any event model via
…		…
1583	specified in the variable.	2519	specified in the variable.
1584		2520
1585	You can make AnyEvent completely ignore this variable by deleting it	2521	You can make AnyEvent completely ignore this variable by deleting it
1586	before the first watcher gets created, e.g. with a C<BEGIN> block:	2522	before the first watcher gets created, e.g. with a C<BEGIN> block:
1587		2523
1588	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2524	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1589		2525
1590	use AnyEvent;	2526	use AnyEvent;
1591		2527
1592	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2528	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1593	be used to probe what backend is used and gain other information (which is	2529	be used to probe what backend is used and gain other information (which is
1594	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2530	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2531	$ENV{PERL_ANYEVENT_STRICT}.
		2532
		2533	Note that AnyEvent will remove I<all> environment variables starting with
		2534	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2535	enabled.
		2536
		2537
		2538	=head1 BUGS
		2539
		2540	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2541	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2542	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2543	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2544	pronounced).
1595		2545
1596		2546
1597	=head1 SEE ALSO	2547	=head1 SEE ALSO
1598		2548
1599	Utility functions: L<AnyEvent::Util>.	2549	Utility functions: L<AnyEvent::Util>.
…		…
1602	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2552	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1603		2553
1604	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2554	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1605	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2555	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1606	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2556	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1607	L<AnyEvent::Impl::POE>.	2557	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1608		2558
1609	Non-blocking file handles, sockets, TCP clients and	2559	Non-blocking file handles, sockets, TCP clients and
1610	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2560	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1611		2561
1612	Asynchronous DNS: L<AnyEvent::DNS>.	2562	Asynchronous DNS: L<AnyEvent::DNS>.
1613		2563
1614	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2564	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2565	L<Coro::Event>,
1615		2566
1616	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2567	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2568	L<AnyEvent::HTTP>.
1617		2569
1618		2570
1619	=head1 AUTHOR	2571	=head1 AUTHOR
1620		2572
1621	Marc Lehmann <schmorp@schmorp.de>	2573	Marc Lehmann <schmorp@schmorp.de>
1622	http://home.schmorp.de/	2574	http://home.schmorp.de/
1623		2575
1624	=cut	2576	=cut
1625		2577
1626	1	2578	1
1627		2579

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