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Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs.
Revision 1.289 by root, Tue Sep 1 16:44:58 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
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	156	is in control).
125		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
126	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
127	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
128	to it).	166	to it).
129		167
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		172
135	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
136		174
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
139	undef $w;	177	undef $w;
140	});	178	});
141		179
142	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,
143	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
144	declared.	182	declared.
145		183
146	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
147		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
148	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
149	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
150		194
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
154	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.
155	becomes ready.
156		206
157	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
160		210
…		…
164		214
165	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
166	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
167	handles.	217	handles.
168		218
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	224	warn "read: $input\n";
175	undef $w;	225	undef $w;
176	});	226	});
177		227
178	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
179		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
180	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 >>
181	method with the following mandatory arguments:	239	method with the following mandatory arguments:
182		240
183	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
184	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
…		…
186		244
187	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
190		248
191	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
192	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
193	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.
194		254
195	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.
196		258
197	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	262	warn "timeout\n";
200	});	263	});
201		264
202	# to cancel the timer:	265	# to cancel the timer:
203	undef $w;	266	undef $w;
204		267
205	Example 2:
206
207	# 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.
208	my $w;
209		269
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
213	};	272	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		273
218	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
219		275
220	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
221	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
…		…
243		299
244	This returns the "current wallclock time" as a fractional number of	300	This returns the "current wallclock time" as a fractional number of
245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>	301	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
246	return, and the result is guaranteed to be compatible with those).	302	return, and the result is guaranteed to be compatible with those).
247		303
248	It progresses independently of any event loop processing.	304	It progresses independently of any event loop processing, i.e. each call
249		305	will check the system clock, which usually gets updated frequently.
250	In almost all cases (in all cases if you don't care), this is the function
251	to call when you want to know the current time.
252		306
253	=item AnyEvent->now	307	=item AnyEvent->now
254		308
255	This also returns the "current wallclock time", but unlike C<time>, above,	309	This also returns the "current wallclock time", but unlike C<time>, above,
256	this value might change only once per event loop iteration, depending on	310	this value might change only once per event loop iteration, depending on
257	the event loop (most return the same time as C<time>, above). This is the	311	the event loop (most return the same time as C<time>, above). This is the
258	time that AnyEvent timers get scheduled against.	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.
259		323
260	For a practical example of when these times differ, consider L<Event::Lib>	324	For a practical example of when these times differ, consider L<Event::Lib>
261	and L<EV> and the following set-up:	325	and L<EV> and the following set-up:
262		326
263	The event loop is running and has just invoked one of your callback at	327	The event loop is running and has just invoked one of your callback at
…		…
268		332
269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will	333	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
270	both return C<501>, because that is the current time, and the timer will	334	both return C<501>, because that is the current time, and the timer will
271	be scheduled to fire at time=504 (C<501> + C<3>).	335	be scheduled to fire at time=504 (C<501> + C<3>).
272		336
273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current	337	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the	338	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
275	last event processing phase started. With L<EV>, your timer gets scheduled	339	last event processing phase started. With L<EV>, your timer gets scheduled
276	to run at time=503 (C<500> + C<3>).	340	to run at time=503 (C<500> + C<3>).
277		341
278	In one sense, L<Event::Lib> is more exact, as it uses the current time	342	In one sense, L<Event::Lib> is more exact, as it uses the current time
279	regardless of any delays introduced by event processing. However, most	343	regardless of any delays introduced by event processing. However, most
280	callbacks do not expect large delays in processing, so this causes a	344	callbacks do not expect large delays in processing, so this causes a
281	higher drift (and a lot more syscalls to get the current time).	345	higher drift (and a lot more system calls to get the current time).
282		346
283	In another sense, L<EV> is more exact, as your timer will be scheduled at	347	In another sense, L<EV> is more exact, as your timer will be scheduled at
284	the same time, regardless of how long event processing actually took.	348	the same time, regardless of how long event processing actually took.
285		349
286	In either case, if you care (and in most cases, you don't), then you	350	In either case, if you care (and in most cases, you don't), then you
287	can get whatever behaviour you want with any event loop, by taking the	351	can get whatever behaviour you want with any event loop, by taking the
288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
289	account.	353	account.
290		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
291	=back	370	=back
292		371
293	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
294		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
295	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
296	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
297	be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
298		379
299	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
300	presence is undefined and you cannot rely on them. Portable AnyEvent	381	presence is undefined and you cannot rely on them. Portable AnyEvent
301	callbacks cannot use arguments passed to signal watcher callbacks.	382	callbacks cannot use arguments passed to signal watcher callbacks.
302		383
…		…
304	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
305	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,
306	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
307		388
308	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
309	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
310		392
311	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
312	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
313		396
314	Example: exit on SIGINT	397	Example: exit on SIGINT
315		398
316	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
317		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$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
318	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
319		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
320	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.
321		426
322	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,
323	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
324	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
325	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
326	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
327	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).
328		441
329	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
330	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
331	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
332		445
333	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
334	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
335	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.
336		452
337	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
338	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
339	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.
340		461
341	Example: fork a process and wait for it	462	Example: fork a process and wait for it
342		463
343	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
344		465
345	my $pid = fork or exit 5;	466	my $pid = fork or exit 5;
346		467
347	my $w = AnyEvent->child (	468	my $w = AnyEvent->child (
348	pid => $pid,	469	pid => $pid,
349	cb => sub {	470	cb => sub {
350	my ($pid, $status) = @_;	471	my ($pid, $status) = @_;
351	warn "pid $pid exited with status $status";	472	warn "pid $pid exited with status $status";
352	$done->send;	473	$done->send;
353	},	474	},
354	);	475	);
355		476
356	# do something else, then wait for process exit	477	# do something else, then wait for process exit
357	$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	});
358		516
359	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
360		523
361	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
362	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
363	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
364		527
365	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
366	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).
367		530
368	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
369	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.
370		535
371	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
372	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
373	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
374	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
375		541
376	After creation, the condition variable is "false" until it becomes "true"	542	After creation, the condition variable is "false" until it becomes "true"
377	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
378	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<<
379	->send >> method).	545	->send >> method).
…		…
381	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
382	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
383	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
384	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
385	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
386	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.
387		554
388	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
389	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,
390	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
391	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
…		…
425	after => 1,	592	after => 1,
426	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
427	);	594	);
428		595
429	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
430	# calls send	597	# calls ->send
431	$result_ready->recv;	598	$result_ready->recv;
432		599
433	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
434	condition variables are also code references.	601	variables are also callable directly.
435		602
436	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
437	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
438	$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	});
439		623
440	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
441		625
442	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
443	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
…		…
456	immediately from within send.	640	immediately from within send.
457		641
458	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
459	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
460		644
461	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
462	(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
463	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
464	overloading, so as tempting as it may be, passing a condition variable
465	instead of a callback does not work. Both the pure perl and EV loops
466	support overloading, however, as well as all functions that use perl to
467	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
468	example).
469		648
470	=item $cv->croak ($error)	649	=item $cv->croak ($error)
471		650
472	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
473	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
474		653
475	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
476	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.
477		660
478	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
479		662
480	=item $cv->end	663	=item $cv->end
481
482	These two methods are EXPERIMENTAL and MIGHT CHANGE.
483		664
484	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
485	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
486	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
487		668
488	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
489	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
490	>>, 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
491	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
492	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.
493		675
494	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:
495		683
496	my $cv = AnyEvent->condvar;	684	my $cv = AnyEvent->condvar;
497		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
498	my %result;	710	my %result;
499	$cv->begin (sub { $cv->send (\%result) });	711	$cv->begin (sub { shift->send (\%result) });
500		712
501	for my $host (@list_of_hosts) {	713	for my $host (@list_of_hosts) {
502	$cv->begin;	714	$cv->begin;
503	ping_host_then_call_callback $host, sub {	715	ping_host_then_call_callback $host, sub {
504	$result{$host} = ...;	716	$result{$host} = ...;
…		…
519	loop, which serves two important purposes: first, it sets the callback	731	loop, which serves two important purposes: first, it sets the callback
520	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
521	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
522	doesn't execute once).	734	doesn't execute once).
523		735
524	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
525	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
526	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
527	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>.
528		741
529	=back	742	=back
530		743
531	=head3 METHODS FOR CONSUMERS	744	=head3 METHODS FOR CONSUMERS
532		745
…		…
548	function will call C<croak>.	761	function will call C<croak>.
549		762
550	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,
551	in scalar context only the first one will be returned.	764	in scalar context only the first one will be returned.
552		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
553	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
554	(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
555	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
556	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
557	condition variables with some kind of request results and supporting	777	condition variables with some kind of request results and supporting
558	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,
559	while still supporting blocking waits if the caller so desires).	779	while still supporting blocking waits if the caller so desires).
560		780
561	Another reason I<never> to C<< ->recv >> in a module is that you cannot
562	sensibly have two C<< ->recv >>'s in parallel, as that would require
563	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
564	can supply.
565
566	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
567	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
568	versions and also integrates coroutines into AnyEvent, making blocking
569	C<< ->recv >> calls perfectly safe as long as they are done from another
570	coroutine (one that doesn't run the event loop).
571
572	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
573	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
574	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
575	waits otherwise.	784	waits otherwise.
576		785
577	=item $bool = $cv->ready	786	=item $bool = $cv->ready
578		787
579	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
580	C<croak> have been called.	789	C<croak> have been called.
581		790
582	=item $cb = $cv->cb ([new callback])	791	=item $cb = $cv->cb ($cb->($cv))
583		792
584	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
585	replaces it before doing so.	794	replaces it before doing so.
586		795
587	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)
588	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>
589	or at any later time is guaranteed not to block.	799	inside the callback or at any later time is guaranteed not to block.
590		800
591	=back	801	=back
592		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
593	=head1 GLOBAL VARIABLES AND FUNCTIONS	871	=head1 GLOBAL VARIABLES AND FUNCTIONS
594		872
		873	These are not normally required to use AnyEvent, but can be useful to
		874	write AnyEvent extension modules.
		875
595	=over 4	876	=over 4
596		877
597	=item $AnyEvent::MODEL	878	=item $AnyEvent::MODEL
598		879
599	Contains C<undef> until the first watcher is being created. Then it	880	Contains C<undef> until the first watcher is being created, before the
		881	backend has been autodetected.
		882
600	contains the event model that is being used, which is the name of the	883	Afterwards it contains the event model that is being used, which is the
601	Perl class implementing the model. This class is usually one of the	884	name of the Perl class implementing the model. This class is usually one
602	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	885	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
603	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	886	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
604		887	will be C<urxvt::anyevent>).
605	The known classes so far are:
606
607	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
608	AnyEvent::Impl::Event based on Event, second best choice.
609	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
610	AnyEvent::Impl::Glib based on Glib, third-best choice.
611	AnyEvent::Impl::Tk based on Tk, very bad choice.
612	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
614	AnyEvent::Impl::POE based on POE, not generic enough for full support.
615
616	There is no support for WxWidgets, as WxWidgets has no support for
617	watching file handles. However, you can use WxWidgets through the
618	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
619	second, which was considered to be too horrible to even consider for
620	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
621	it's adaptor.
622
623	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
624	autodetecting them.
625		888
626	=item AnyEvent::detect	889	=item AnyEvent::detect
627		890
628	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	891	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
629	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
630	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
631	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>.
632		898
633	=item $guard = AnyEvent::post_detect { BLOCK }	899	=item $guard = AnyEvent::post_detect { BLOCK }
634		900
635	Arranges for the code block to be executed as soon as the event model is	901	Arranges for the code block to be executed as soon as the event model is
636	autodetected (or immediately if this has already happened).	902	autodetected (or immediately if this has already happened).
637		903
		904	The block will be executed I<after> the actual backend has been detected
		905	(C<$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
638	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
639	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
640	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 ||= $guard;
641		935
642	=item @AnyEvent::post_detect	936	=item @AnyEvent::post_detect
643		937
644	If there are any code references in this array (you can C<push> to it	938	If there are any code references in this array (you can C<push> to it
645	before or after loading AnyEvent), then they will called directly after	939	before or after loading AnyEvent), then they will called directly after
646	the event loop has been chosen.	940	the event loop has been chosen.
647		941
648	You should check C<$AnyEvent::MODEL> before adding to this array, though:	942	You should check C<$AnyEvent::MODEL> before adding to this array, though:
649	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
650	and the array will be ignored.	944	array will be ignored.
651		945
652	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.
653		953
654	=back	954	=back
655		955
656	=head1 WHAT TO DO IN A MODULE	956	=head1 WHAT TO DO IN A MODULE
657		957
…		…
712		1012
713		1013
714	=head1 OTHER MODULES	1014	=head1 OTHER MODULES
715		1015
716	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
717	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
718	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
719	available via CPAN.	1019	come with AnyEvent, most are available via CPAN.
720		1020
721	=over 4	1021	=over 4
722		1022
723	=item L<AnyEvent::Util>	1023	=item L<AnyEvent::Util>
724		1024
725	Contains various utility functions that replace often-used but blocking	1025	Contains various utility functions that replace often-used but blocking
726	functions such as C<inet_aton> by event-/callback-based versions.	1026	functions such as C<inet_aton> by event-/callback-based versions.
727
728	=item L<AnyEvent::Handle>
729
730	Provide read and write buffers and manages watchers for reads and writes.
731		1027
732	=item L<AnyEvent::Socket>	1028	=item L<AnyEvent::Socket>
733		1029
734	Provides various utility functions for (internet protocol) sockets,	1030	Provides various utility functions for (internet protocol) sockets,
735	addresses and name resolution. Also functions to create non-blocking tcp	1031	addresses and name resolution. Also functions to create non-blocking tcp
736	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.
737		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
738	=item L<AnyEvent::DNS>	1040	=item L<AnyEvent::DNS>
739		1041
740	Provides rich asynchronous DNS resolver capabilities.	1042	Provides rich asynchronous DNS resolver capabilities.
741		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
742	=item L<AnyEvent::HTTPD>	1049	=item L<AnyEvent::HTTPD>
743		1050
744	Provides a simple web application server framework.	1051	Provides a simple web application server framework.
745		1052
746	=item L<AnyEvent::FastPing>	1053	=item L<AnyEvent::FastPing>
747		1054
748	The fastest ping in the west.	1055	The fastest ping in the west.
749		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
750	=item L<Net::IRC3>	1076	=item L<AnyEvent::IRC>
751		1077
752	AnyEvent based IRC client module family.	1078	AnyEvent based IRC client module family (replacing the older Net::IRC3).
753		1079
754	=item L<Net::XMPP2>	1080	=item L<AnyEvent::XMPP>
755		1081
756	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>).
757		1089
758	=item L<Net::FCP>	1090	=item L<Net::FCP>
759		1091
760	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1092	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
761	of AnyEvent.	1093	of AnyEvent.
…		…
766		1098
767	=item L<Coro>	1099	=item L<Coro>
768		1100
769	Has special support for AnyEvent via L<Coro::AnyEvent>.	1101	Has special support for AnyEvent via L<Coro::AnyEvent>.
770		1102
771	=item L<AnyEvent::AIO>, L<IO::AIO>
772
773	Truly asynchronous I/O, should be in the toolbox of every event
774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
775	together.
776
777	=item L<AnyEvent::BDB>, L<BDB>
778
779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
780	IO::AIO and AnyEvent together.
781
782	=item L<IO::Lambda>
783
784	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
785
786	=back	1103	=back
787		1104
788	=cut	1105	=cut
789		1106
790	package AnyEvent;	1107	package AnyEvent;
791		1108
792	no warnings;	1109	# basically a tuned-down version of common::sense
793	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	}
794		1116
		1117	BEGIN { AnyEvent::common_sense }
		1118
795	use Carp;	1119	use Carp ();
796		1120
797	our $VERSION = '4.05';	1121	our $VERSION = '5.112';
798	our $MODEL;	1122	our $MODEL;
799		1123
800	our $AUTOLOAD;	1124	our $AUTOLOAD;
801	our @ISA;	1125	our @ISA;
802		1126
803	our @REGISTRY;	1127	our @REGISTRY;
804		1128
805	our $WIN32;	1129	our $WIN32;
806		1130
		1131	our $VERBOSE;
		1132
807	BEGIN {	1133	BEGIN {
808	my $win32 = ! ! ($^O =~ /mswin32/i);	1134	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
809	eval "sub WIN32(){ $win32 }";	1135	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
810	}
811		1136
		1137	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1138	if ${^TAINT};
		1139
812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1140	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1141
		1142	}
		1143
		1144	our $MAX_SIGNAL_LATENCY = 10;
813		1145
814	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1146	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
815		1147
816	{	1148	{
817	my $idx;	1149	my $idx;
…		…
819	for reverse split /\s*,\s*/,	1151	for reverse split /\s*,\s*/,
820	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1152	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
821	}	1153	}
822		1154
823	my @models = (	1155	my @models = (
824	[EV:: => AnyEvent::Impl::EV::],	1156	[EV:: => AnyEvent::Impl::EV:: , 1],
825	[Event:: => AnyEvent::Impl::Event::],
826	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1157	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
827	# everything below here will not be autoprobed	1158	# everything below here will not (normally) be autoprobed
828	# as the pureperl backend should work everywhere	1159	# as the pureperl backend should work everywhere
829	# 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
830	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1165	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
831	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1166	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1167	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
835	[Wx:: => AnyEvent::Impl::POE::],	1168	[Wx:: => AnyEvent::Impl::POE::],
836	[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
837	);	1178	);
838		1179
839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1180	our %method = map +($_ => 1),
		1181	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
840		1182
841	our @post_detect;	1183	our @post_detect;
842		1184
843	sub post_detect(&) {	1185	sub post_detect(&) {
844	my ($cb) = @_;	1186	my ($cb) = @_;
845		1187
846	if ($MODEL) {	1188	if ($MODEL) {
847	$cb->();	1189	$cb->();
848		1190
849	1	1191	undef
850	} else {	1192	} else {
851	push @post_detect, $cb;	1193	push @post_detect, $cb;
852		1194
853	defined wantarray	1195	defined wantarray
854	? bless \$cb, "AnyEvent::Util::PostDetect"	1196	? bless \$cb, "AnyEvent::Util::postdetect"
855	: ()	1197	: ()
856	}	1198	}
857	}	1199	}
858		1200
859	sub AnyEvent::Util::PostDetect::DESTROY {	1201	sub AnyEvent::Util::postdetect::DESTROY {
860	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1202	@post_detect = grep $_ != ${$_[0]}, @post_detect;
861	}	1203	}
862		1204
863	sub detect() {	1205	sub detect() {
864	unless ($MODEL) {	1206	unless ($MODEL) {
865	no strict 'refs';
866	local $SIG{__DIE__};	1207	local $SIG{__DIE__};
867		1208
868	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1209	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
869	my $model = "AnyEvent::Impl::$1";	1210	my $model = "AnyEvent::Impl::$1";
870	if (eval "require $model") {	1211	if (eval "require $model") {
871	$MODEL = $model;	1212	$MODEL = $model;
872	warn "AnyEvent: loaded model '$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 $VERBOSE >= 2;
873	} else {	1214	} else {
874	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1215	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
875	}	1216	}
876	}	1217	}
877		1218
878	# check for already loaded models	1219	# check for already loaded models
879	unless ($MODEL) {	1220	unless ($MODEL) {
880	for (@REGISTRY, @models) {	1221	for (@REGISTRY, @models) {
881	my ($package, $model) = @$_;	1222	my ($package, $model) = @$_;
882	if (${"$package\::VERSION"} > 0) {	1223	if (${"$package\::VERSION"} > 0) {
883	if (eval "require $model") {	1224	if (eval "require $model") {
884	$MODEL = $model;	1225	$MODEL = $model;
885	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1226	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
886	last;	1227	last;
887	}	1228	}
888	}	1229	}
889	}	1230	}
890		1231
891	unless ($MODEL) {	1232	unless ($MODEL) {
892	# try to load a model	1233	# try to autoload a model
893
894	for (@REGISTRY, @models) {	1234	for (@REGISTRY, @models) {
895	my ($package, $model) = @$_;	1235	my ($package, $model, $autoload) = @$_;
		1236	if (
		1237	$autoload
896	if (eval "require $package"	1238	and eval "require $package"
897	and ${"$package\::VERSION"} > 0	1239	and ${"$package\::VERSION"} > 0
898	and eval "require $model") {	1240	and eval "require $model"
		1241	) {
899	$MODEL = $model;	1242	$MODEL = $model;
900	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1243	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
901	last;	1244	last;
902	}	1245	}
903	}	1246	}
904		1247
905	$MODEL	1248	$MODEL
906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1249	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
907	}	1250	}
908	}	1251	}
909		1252
		1253	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1254
910	unshift @ISA, $MODEL;	1255	unshift @ISA, $MODEL;
911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1256
		1257	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
912		1258
913	(shift @post_detect)->() while @post_detect;	1259	(shift @post_detect)->() while @post_detect;
914	}	1260	}
915		1261
916	$MODEL	1262	$MODEL
…		…
918		1264
919	sub AUTOLOAD {	1265	sub AUTOLOAD {
920	(my $func = $AUTOLOAD) =~ s/.*://;	1266	(my $func = $AUTOLOAD) =~ s/.*://;
921		1267
922	$method{$func}	1268	$method{$func}
923	or croak "$func: not a valid method for AnyEvent objects";	1269	or Carp::croak "$func: not a valid method for AnyEvent objects";
924		1270
925	detect unless $MODEL;	1271	detect unless $MODEL;
926		1272
927	my $class = shift;	1273	my $class = shift;
928	$class->$func (@_);	1274	$class->$func (@_);
929	}	1275	}
930		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
931	package AnyEvent::Base;	1344	package AnyEvent::Base;
932		1345
933	# default implementation for now and time	1346	# default implementations for many methods
934		1347
935	use Time::HiRes ();	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	}
936		1358
937	sub time { Time::HiRes::time }	1359	&_time
938	sub now { Time::HiRes::time }	1360	}
		1361
		1362	sub time { _time }
		1363	sub now { _time }
		1364	sub now_update { }
939		1365
940	# default implementation for ->condvar	1366	# default implementation for ->condvar
941		1367
942	sub condvar {	1368	sub condvar {
943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1369	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
944	}	1370	}
945		1371
946	# default implementation for ->signal	1372	# default implementation for ->signal
947		1373
948	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 }
949		1450
950	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 {
951	my (undef, %arg) = @_;	1488	my (undef, %arg) = @_;
952		1489
953	my $signal = uc $arg{signal}	1490	my $signal = uc $arg{signal}
954	or Carp::croak "required option 'signal' is missing";	1491	or Carp::croak "required option 'signal' is missing";
955		1492
		1493	if ($HAVE_ASYNC_INTERRUPT) {
		1494	# async::interrupt
		1495
		1496	$signal = sig2num $signal;
956	$SIG_CB{$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
957	$SIG{$signal} ||= sub {	1513	$SIG{$signal} ||= sub {
958	$_->() 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	};
959	};	1542	};
960		1543	die if $@;
961	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1544	&signal
962	}
963
964	sub AnyEvent::Base::Signal::DESTROY {
965	my ($signal, $cb) = @{$_[0]};
966
967	delete $SIG_CB{$signal}{$cb};
968
969	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
970	}	1545	}
971		1546
972	# default implementation for ->child	1547	# default implementation for ->child
973		1548
974	our %PID_CB;	1549	our %PID_CB;
975	our $CHLD_W;	1550	our $CHLD_W;
976	our $CHLD_DELAY_W;	1551	our $CHLD_DELAY_W;
977	our $PID_IDLE;
978	our $WNOHANG;	1552	our $WNOHANG;
979		1553
980	sub _child_wait {	1554	sub _emit_childstatus($$) {
981	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1555	my (undef, $rpid, $rstatus) = @_;
		1556
		1557	$_->($rpid, $rstatus)
982	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1558	for values %{ $PID_CB{$rpid} || {} },
983	(values %{ $PID_CB{0} || {} });	1559	values %{ $PID_CB{0} || {} };
984	}
985
986	undef $PID_IDLE;
987	}	1560	}
988		1561
989	sub _sigchld {	1562	sub _sigchld {
990	# make sure we deliver these changes "synchronous" with the event loop.	1563	my $pid;
991	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1564
992	undef $CHLD_DELAY_W;	1565	AnyEvent->_emit_childstatus ($pid, $?)
993	&_child_wait;	1566	while ($pid = waitpid -1, $WNOHANG) > 0;
994	});
995	}	1567	}
996		1568
997	sub child {	1569	sub child {
998	my (undef, %arg) = @_;	1570	my (undef, %arg) = @_;
999		1571
1000	defined (my $pid = $arg{pid} + 0)	1572	defined (my $pid = $arg{pid} + 0)
1001	or Carp::croak "required option 'pid' is missing";	1573	or Carp::croak "required option 'pid' is missing";
1002		1574
1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1575	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1004		1576
1005	unless ($WNOHANG) {	1577	# WNOHANG is almost cetrainly 1 everywhere
		1578	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1579	? 1
1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1580	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1007	}
1008		1581
1009	unless ($CHLD_W) {	1582	unless ($CHLD_W) {
1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1583	$CHLD_W = AE::signal CHLD => \&_sigchld;
1011	# 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
1012	&_sigchld;	1585	&_sigchld;
1013	}	1586	}
1014		1587
1015	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1588	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1016	}	1589	}
1017		1590
1018	sub AnyEvent::Base::Child::DESTROY {	1591	sub AnyEvent::Base::child::DESTROY {
1019	my ($pid, $cb) = @{$_[0]};	1592	my ($pid, $cb) = @{$_[0]};
1020		1593
1021	delete $PID_CB{$pid}{$cb};	1594	delete $PID_CB{$pid}{$cb};
1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1595	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1023		1596
1024	undef $CHLD_W unless keys %PID_CB;	1597	undef $CHLD_W unless keys %PID_CB;
1025	}	1598	}
1026		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
1027	package AnyEvent::CondVar;	1636	package AnyEvent::CondVar;
1028		1637
1029	our @ISA = AnyEvent::CondVar::Base::;	1638	our @ISA = AnyEvent::CondVar::Base::;
1030		1639
1031	package AnyEvent::CondVar::Base;	1640	package AnyEvent::CondVar::Base;
1032		1641
1033	use overload	1642	#use overload
1034	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1643	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1035	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;
1036		1653
1037	sub _send {	1654	sub _send {
1038	# nop	1655	# nop
1039	}	1656	}
1040		1657
…		…
1053	sub ready {	1670	sub ready {
1054	$_[0]{_ae_sent}	1671	$_[0]{_ae_sent}
1055	}	1672	}
1056		1673
1057	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 $WAITING = 1;
1058	AnyEvent->one_event while !$_[0]{_ae_sent};	1680	AnyEvent->one_event while !$_[0]{_ae_sent};
1059	}	1681	}
1060		1682
1061	sub recv {	1683	sub recv {
1062	$_[0]->_wait;	1684	$_[0]->_wait;
…		…
1064	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1686	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1065	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1687	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1066	}	1688	}
1067		1689
1068	sub cb {	1690	sub cb {
1069	$_[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
1070	$_[0]{_ae_cb}	1698	$cv->{_ae_cb}
1071	}	1699	}
1072		1700
1073	sub begin {	1701	sub begin {
1074	++$_[0]{_ae_counter};	1702	++$_[0]{_ae_counter};
1075	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1703	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1081	}	1709	}
1082		1710
1083	# undocumented/compatibility with pre-3.4	1711	# undocumented/compatibility with pre-3.4
1084	*broadcast = \&send;	1712	*broadcast = \&send;
1085	*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
1086		1852
1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1853	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1088		1854
1089	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
1090	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
…		…
1124		1890
1125	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
1126	condition variables: code blocking while waiting for a condition will	1892	condition variables: code blocking while waiting for a condition will
1127	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
1128	not be done in an interactive application, so it makes sense.	1894	not be done in an interactive application, so it makes sense.
1129
1130	=head1 ENVIRONMENT VARIABLES
1131
1132	The following environment variables are used by this module:
1133
1134	=over 4
1135
1136	=item C<PERL_ANYEVENT_VERBOSE>
1137
1138	By default, AnyEvent will be completely silent except in fatal
1139	conditions. You can set this environment variable to make AnyEvent more
1140	talkative.
1141
1142	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1143	conditions, such as not being able to load the event model specified by
1144	C<PERL_ANYEVENT_MODEL>.
1145
1146	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1147	model it chooses.
1148
1149	=item C<PERL_ANYEVENT_MODEL>
1150
1151	This can be used to specify the event model to be used by AnyEvent, before
1152	auto detection and -probing kicks in. It must be a string consisting
1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1154	and the resulting module name is loaded and if the load was successful,
1155	used as event model. If it fails to load AnyEvent will proceed with
1156	auto detection and -probing.
1157
1158	This functionality might change in future versions.
1159
1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1161	could start your program like this:
1162
1163	PERL_ANYEVENT_MODEL=Perl perl ...
1164
1165	=item C<PERL_ANYEVENT_PROTOCOLS>
1166
1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1169	of auto probing).
1170
1171	Must be set to a comma-separated list of protocols or address families,
1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1173	used, and preference will be given to protocols mentioned earlier in the
1174	list.
1175
1176	This variable can effectively be used for denial-of-service attacks
1177	against local programs (e.g. when setuid), although the impact is likely
1178	small, as the program has to handle connection errors already-
1179
1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1182	- only support IPv4, never try to resolve or contact IPv6
1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1184	IPv6, but prefer IPv6 over IPv4.
1185
1186	=item C<PERL_ANYEVENT_EDNS0>
1187
1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic, but
1190	some (broken) firewalls drop such DNS packets, which is why it is off by
1191	default.
1192
1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1194	EDNS0 in its DNS requests.
1195
1196	=item C<PERL_ANYEVENT_MAX_FORKS>
1197
1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1199	will create in parallel.
1200
1201	=back
1202		1895
1203	=head1 EXAMPLE PROGRAM	1896	=head1 EXAMPLE PROGRAM
1204		1897
1205	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
1206	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
…		…
1219	warn "read: $input\n"; # output what has been read	1912	warn "read: $input\n"; # output what has been read
1220	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1913	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1221	},	1914	},
1222	);	1915	);
1223		1916
1224	my $time_watcher; # can only be used once
1225
1226	sub new_timer {
1227	$timer = AnyEvent->timer (after => 1, cb => sub {	1917	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1228	warn "timeout\n"; # print 'timeout' about every second	1918	warn "timeout\n"; # print 'timeout' at most every second
1229	&new_timer; # and restart the time
1230	});	1919	});
1231	}
1232
1233	new_timer; # create first timer
1234		1920
1235	$cv->recv; # wait until user enters /^q/i	1921	$cv->recv; # wait until user enters /^q/i
1236		1922
1237	=head1 REAL-WORLD EXAMPLE	1923	=head1 REAL-WORLD EXAMPLE
1238		1924
…		…
1369	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
1370	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,
1371	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.
1372		2058
1373	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
1374	distribution.	2060	distribution. It uses the L<AE> interface, which makes a real difference
		2061	for the EV and Perl backends only.
1375		2062
1376	=head3 Explanation of the columns	2063	=head3 Explanation of the columns
1377		2064
1378	I<watcher> is the number of event watchers created/destroyed. Since	2065	I<watcher> is the number of event watchers created/destroyed. Since
1379	different event models feature vastly different performances, each event	2066	different event models feature vastly different performances, each event
…		…
1400	watcher.	2087	watcher.
1401		2088
1402	=head3 Results	2089	=head3 Results
1403		2090
1404	name watchers bytes create invoke destroy comment	2091	name watchers bytes create invoke destroy comment
1405	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
1406	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
1407	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
1408	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
1409	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
1410	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
1411	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
1412	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
1413	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
1414	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
1415		2104
1416	=head3 Discussion	2105	=head3 Discussion
1417		2106
1418	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
1419	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)
…		…
1431	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2120	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1432	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
1433	cycles with POE.	2122	cycles with POE.
1434		2123
1435	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
1436	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
1437	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).
1438	natively.
1439		2129
1440	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
1441	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
1442	interpreter and the backend itself). Nevertheless this shows that it	2132	interpreter and the backend itself). Nevertheless this shows that it
1443	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
1444	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
1445	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.
1446		2136
1447	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
1448	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.
1449		2142
1450	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
1451	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
1452	C<Event>. However, Glib scales extremely badly, doubling the number of	2145	C<Event>. However, Glib scales extremely badly, doubling the number of
1453	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,
…		…
1514	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
1515	(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
1516	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.
1517		2210
1518	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
1519	distribution.	2212	distribution. It uses the L<AE> interface, which makes a real difference
		2213	for the EV and Perl backends only.
1520		2214
1521	=head3 Explanation of the columns	2215	=head3 Explanation of the columns
1522		2216
1523	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
1524	each server has a read and write socket end).	2218	each server has a read and write socket end).
…		…
1531	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
1532	a new one that moves the timeout into the future.	2226	a new one that moves the timeout into the future.
1533		2227
1534	=head3 Results	2228	=head3 Results
1535		2229
1536	name sockets create request	2230	name sockets create request
1537	EV 20000 69.01 11.16	2231	EV 20000 62.66 7.99
1538	Perl 20000 73.32 35.87	2232	Perl 20000 68.32 32.64
1539	Event 20000 212.62 257.32	2233	IOAsync 20000 174.06 101.15 epoll
1540	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
1541	POE 20000 349.67 12317.24 uses POE::Loop::Event	2237	POE 20000 341.54 12086.32 uses POE::Loop::Event
1542		2238
1543	=head3 Discussion	2239	=head3 Discussion
1544		2240
1545	This benchmark I<does> measure scalability and overall performance of the	2241	This benchmark I<does> measure scalability and overall performance of the
1546	particular event loop.	2242	particular event loop.
…		…
1548	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
1549	is relatively high, though.	2245	is relatively high, though.
1550		2246
1551	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
1552	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.
1553		2252
1554	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
1555	understand why). Callback invocation also has a high overhead compared to	2254	understand why). Callback invocation also has a high overhead compared to
1556	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
1557	uses select or poll in basically all documented configurations.	2256	uses select or poll in basically all documented configurations.
…		…
1620	=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
1621	watchers, as the management overhead dominates.	2320	watchers, as the management overhead dominates.
1622		2321
1623	=back	2322	=back
1624		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
1625		2500
1626	=head1 FORK	2501	=head1 FORK
1627		2502
1628	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
1629	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>
1630	calls. Only L<EV> is fully fork-aware.	2505	calls. Only L<EV> is fully fork-aware.
1631		2506
1632	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
1633	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.
1634		2510
1635		2511
1636	=head1 SECURITY CONSIDERATIONS	2512	=head1 SECURITY CONSIDERATIONS
1637		2513
1638	AnyEvent can be forced to load any event model via	2514	AnyEvent can be forced to load any event model via
…		…
1643	specified in the variable.	2519	specified in the variable.
1644		2520
1645	You can make AnyEvent completely ignore this variable by deleting it	2521	You can make AnyEvent completely ignore this variable by deleting it
1646	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:
1647		2523
1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2524	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1649		2525
1650	use AnyEvent;	2526	use AnyEvent;
1651		2527
1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2528	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1653	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
1654	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).
1655		2545
1656		2546
1657	=head1 SEE ALSO	2547	=head1 SEE ALSO
1658		2548
1659	Utility functions: L<AnyEvent::Util>.	2549	Utility functions: L<AnyEvent::Util>.
…		…
1662	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2552	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1663		2553
1664	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2554	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1665	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>,
1666	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2556	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1667	L<AnyEvent::Impl::POE>.	2557	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1668		2558
1669	Non-blocking file handles, sockets, TCP clients and	2559	Non-blocking file handles, sockets, TCP clients and
1670	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2560	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1671		2561
1672	Asynchronous DNS: L<AnyEvent::DNS>.	2562	Asynchronous DNS: L<AnyEvent::DNS>.
1673		2563
1674	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>,
1675		2566
1676	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>.
1677		2569
1678		2570
1679	=head1 AUTHOR	2571	=head1 AUTHOR
1680		2572
1681	Marc Lehmann <schmorp@schmorp.de>	2573	Marc Lehmann <schmorp@schmorp.de>
1682	http://home.schmorp.de/	2574	http://home.schmorp.de/
1683		2575
1684	=cut	2576	=cut
1685		2577
1686	1	2578	1
1687		2579

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