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Revision 1.266 by root, Thu Jul 30 03:41:56 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 });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
28		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.
		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	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
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
33		58
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
36		61
37	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
38	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
39	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
40	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,
41	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
42	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
43		69
44	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
45	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
46	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
47	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
48	model you use.	74	model you use.
49		75
50	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
51	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
52	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
53	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
54	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
55	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.
56		82
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	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
59	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
60	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,
61	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
62	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
63	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
64	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
65		91
66	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
67	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
68	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
69	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
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
128	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
129	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
130	is in control).	156	is in control).
131		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
132	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
133	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
134	to it).	166	to it).
135		167
136	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.
…		…
149	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
150	declared.	182	declared.
151		183
152	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
153		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
154	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
155	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
156		194
157	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
158	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
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
160	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.
161	becomes ready.
162		206
163	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
166		210
…		…
170		214
171	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
172	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
173	handles.	217	handles.
174		218
175	Example:
176
177	# 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
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	224	warn "read: $input\n";
181	undef $w;	225	undef $w;
182	});	226	});
183		227
184	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
185		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
186	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 >>
187	method with the following mandatory arguments:	239	method with the following mandatory arguments:
188		240
189	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
190	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
…		…
192		244
193	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
196		248
197	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
198	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
199	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.
200		254
201	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.
202		258
203	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	262	warn "timeout\n";
206	});	263	});
207		264
208	# to cancel the timer:	265	# to cancel the timer:
209	undef $w;	266	undef $w;
210		267
211	Example 2:
212
213	# 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.
214	my $w;
215		269
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
219	};	272	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		273
224	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
225		275
226	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
227	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
…		…
300	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
301	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
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	353	account.
304		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
305	=back	370	=back
306		371
307	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
308		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
309	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
310	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
311	be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
312		379
313	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	381	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	382	callbacks cannot use arguments passed to signal watcher callbacks.
316		383
…		…
318	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
319	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,
320	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
321		388
322	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
323	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
324		392
325	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
326	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
327		396
328	Example: exit on SIGINT	397	Example: exit on SIGINT
329		398
330	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot do
		405	race-free signal handling in perl. AnyEvent will try to do it's best, but
		406	in some cases, signals will be delayed. The maximum time a signal might
		407	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		408	seconds). This variable can be changed only before the first signal
		409	watcher is created, and should be left alone otherwise. Higher values
		410	will cause fewer spurious wake-ups, which is better for power and CPU
		411	saving. All these problems can be avoided by installing the optional
		412	L<Async::Interrupt> module. This will not work with inherently broken
		413	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		414	currently, as POE does it's own workaround with one-second latency). With
		415	those, you just have to suffer the delays.
		416
332	=head2 CHILD PROCESS WATCHERS	417	=head2 CHILD PROCESS WATCHERS
333		418
		419	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		420
334	You can also watch on a child process exit and catch its exit status.	421	You can also watch on a child process exit and catch its exit status.
335		422
336	The child process is specified by the C<pid> argument (if set to C<0>, it	423	The child process is specified by the C<pid> argument (one some backends,
337	watches for any child process exit). The watcher will trigger as often	424	using C<0> watches for any child process exit, on others this will
338	as status change for the child are received. This works by installing a	425	croak). The watcher will be triggered only when the child process has
339	signal handler for C<SIGCHLD>. The callback will be called with the pid	426	finished and an exit status is available, not on any trace events
340	and exit status (as returned by waitpid), so unlike other watcher types,	427	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	428
		429	The callback will be called with the pid and exit status (as returned by
		430	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		431	callback arguments.
		432
		433	This watcher type works by installing a signal handler for C<SIGCHLD>,
		434	and since it cannot be shared, nothing else should use SIGCHLD or reap
		435	random child processes (waiting for specific child processes, e.g. inside
		436	C<system>, is just fine).
342		437
343	There is a slight catch to child watchers, however: you usually start them	438	There is a slight catch to child watchers, however: you usually start them
344	I<after> the child process was created, and this means the process could	439	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	440	have exited already (and no SIGCHLD will be sent anymore).
346		441
347	Not all event models handle this correctly (POE doesn't), but even for	442	Not all event models handle this correctly (neither POE nor IO::Async do,
		443	see their AnyEvent::Impl manpages for details), but even for event models
348	event models that I<do> handle this correctly, they usually need to be	444	that I<do> handle this correctly, they usually need to be loaded before
349	loaded before the process exits (i.e. before you fork in the first place).	445	the process exits (i.e. before you fork in the first place). AnyEvent's
		446	pure perl event loop handles all cases correctly regardless of when you
		447	start the watcher.
350		448
351	This means you cannot create a child watcher as the very first thing in an	449	This means you cannot create a child watcher as the very first
352	AnyEvent program, you I<have> to create at least one watcher before you	450	thing in an AnyEvent program, you I<have> to create at least one
353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	451	watcher before you C<fork> the child (alternatively, you can call
		452	C<AnyEvent::detect>).
		453
		454	As most event loops do not support waiting for child events, they will be
		455	emulated by AnyEvent in most cases, in which the latency and race problems
		456	mentioned in the description of signal watchers apply.
354		457
355	Example: fork a process and wait for it	458	Example: fork a process and wait for it
356		459
357	my $done = AnyEvent->condvar;	460	my $done = AnyEvent->condvar;
358		461
…		…
368	);	471	);
369		472
370	# do something else, then wait for process exit	473	# do something else, then wait for process exit
371	$done->recv;	474	$done->recv;
372		475
		476	=head2 IDLE WATCHERS
		477
		478	$w = AnyEvent->idle (cb => <callback>);
		479
		480	Sometimes there is a need to do something, but it is not so important
		481	to do it instantly, but only when there is nothing better to do. This
		482	"nothing better to do" is usually defined to be "no other events need
		483	attention by the event loop".
		484
		485	Idle watchers ideally get invoked when the event loop has nothing
		486	better to do, just before it would block the process to wait for new
		487	events. Instead of blocking, the idle watcher is invoked.
		488
		489	Most event loops unfortunately do not really support idle watchers (only
		490	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		491	will simply call the callback "from time to time".
		492
		493	Example: read lines from STDIN, but only process them when the
		494	program is otherwise idle:
		495
		496	my @lines; # read data
		497	my $idle_w;
		498	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		499	push @lines, scalar <STDIN>;
		500
		501	# start an idle watcher, if not already done
		502	$idle_w ||= AnyEvent->idle (cb => sub {
		503	# handle only one line, when there are lines left
		504	if (my $line = shift @lines) {
		505	print "handled when idle: $line";
		506	} else {
		507	# otherwise disable the idle watcher again
		508	undef $idle_w;
		509	}
		510	});
		511	});
		512
373	=head2 CONDITION VARIABLES	513	=head2 CONDITION VARIABLES
		514
		515	$cv = AnyEvent->condvar;
		516
		517	$cv->send (<list>);
		518	my @res = $cv->recv;
374		519
375	If you are familiar with some event loops you will know that all of them	520	If you are familiar with some event loops you will know that all of them
376	require you to run some blocking "loop", "run" or similar function that	521	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	522	will actively watch for new events and call your callbacks.
378		523
379	AnyEvent is different, it expects somebody else to run the event loop and	524	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	525	loop and will only block when necessary (usually when told by the user).
381		526
382	The instrument to do that is called a "condition variable", so called	527	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	528	because they represent a condition that must become true.
		529
		530	Now is probably a good time to look at the examples further below.
384		531
385	Condition variables can be created by calling the C<< AnyEvent->condvar	532	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	533	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	534	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	535	becomes true, with the condition variable as the first argument (but not
		536	the results).
389		537
390	After creation, the condition variable is "false" until it becomes "true"	538	After creation, the condition variable is "false" until it becomes "true"
391	by calling the C<send> method (or calling the condition variable as if it	539	by calling the C<send> method (or calling the condition variable as if it
392	were a callback, read about the caveats in the description for the C<<	540	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	541	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	543	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	544	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	545	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	546	another way to call them is transactions - each condition variable can be
399	used to represent a transaction, which finishes at some point and delivers	547	used to represent a transaction, which finishes at some point and delivers
400	a result.	548	a result. And yet some people know them as "futures" - a promise to
		549	compute/deliver something that you can wait for.
401		550
402	Condition variables are very useful to signal that something has finished,	551	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	552	for example, if you write a module that does asynchronous http requests,
404	then a condition variable would be the ideal candidate to signal the	553	then a condition variable would be the ideal candidate to signal the
405	availability of results. The user can either act when the callback is	554	availability of results. The user can either act when the callback is
…		…
439	after => 1,	588	after => 1,
440	cb => sub { $result_ready->send },	589	cb => sub { $result_ready->send },
441	);	590	);
442		591
443	# this "blocks" (while handling events) till the callback	592	# this "blocks" (while handling events) till the callback
444	# calls send	593	# calls -<send
445	$result_ready->recv;	594	$result_ready->recv;
446		595
447	Example: wait for a timer, but take advantage of the fact that	596	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	597	variables are also callable directly.
449		598
450	my $done = AnyEvent->condvar;	599	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	600	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	601	$done->recv;
		602
		603	Example: Imagine an API that returns a condvar and doesn't support
		604	callbacks. This is how you make a synchronous call, for example from
		605	the main program:
		606
		607	use AnyEvent::CouchDB;
		608
		609	...
		610
		611	my @info = $couchdb->info->recv;
		612
		613	And this is how you would just set a callback to be called whenever the
		614	results are available:
		615
		616	$couchdb->info->cb (sub {
		617	my @info = $_[0]->recv;
		618	});
453		619
454	=head3 METHODS FOR PRODUCERS	620	=head3 METHODS FOR PRODUCERS
455		621
456	These methods should only be used by the producing side, i.e. the	622	These methods should only be used by the producing side, i.e. the
457	code/module that eventually sends the signal. Note that it is also	623	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	636	immediately from within send.
471		637
472	Any arguments passed to the C<send> call will be returned by all	638	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	639	future C<< ->recv >> calls.
474		640
475	Condition variables are overloaded so one can call them directly	641	Condition variables are overloaded so one can call them directly (as if
476	(as a code reference). Calling them directly is the same as calling	642	they were a code reference). Calling them directly is the same as calling
477	C<send>. Note, however, that many C-based event loops do not handle	643	C<send>.
478	overloading, so as tempting as it may be, passing a condition variable
479	instead of a callback does not work. Both the pure perl and EV loops
480	support overloading, however, as well as all functions that use perl to
481	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
482	example).
483		644
484	=item $cv->croak ($error)	645	=item $cv->croak ($error)
485		646
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	647	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	648	C<Carp::croak> with the given error message/object/scalar.
488		649
489	This can be used to signal any errors to the condition variable	650	This can be used to signal any errors to the condition variable
490	user/consumer.	651	user/consumer. Doing it this way instead of calling C<croak> directly
		652	delays the error detetcion, but has the overwhelmign advantage that it
		653	diagnoses the error at the place where the result is expected, and not
		654	deep in some event clalback without connection to the actual code causing
		655	the problem.
491		656
492	=item $cv->begin ([group callback])	657	=item $cv->begin ([group callback])
493		658
494	=item $cv->end	659	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		660
498	These two methods can be used to combine many transactions/events into	661	These two methods can be used to combine many transactions/events into
499	one. For example, a function that pings many hosts in parallel might want	662	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	663	to use a condition variable for the whole process.
501		664
…		…
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	666	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
504	>>, the (last) callback passed to C<begin> will be executed. That callback	667	>>, the (last) callback passed to C<begin> will be executed. That callback
505	is I<supposed> to call C<< ->send >>, but that is not required. If no	668	is I<supposed> to call C<< ->send >>, but that is not required. If no
506	callback was set, C<send> will be called without any arguments.	669	callback was set, C<send> will be called without any arguments.
507		670
508	Let's clarify this with the ping example:	671	You can think of C<< $cv->send >> giving you an OR condition (one call
		672	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		673	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		674
		675	Let's start with a simple example: you have two I/O watchers (for example,
		676	STDOUT and STDERR for a program), and you want to wait for both streams to
		677	close before activating a condvar:
		678
		679	my $cv = AnyEvent->condvar;
		680
		681	$cv->begin; # first watcher
		682	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		683	defined sysread $fh1, my $buf, 4096
		684	or $cv->end;
		685	});
		686
		687	$cv->begin; # second watcher
		688	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		689	defined sysread $fh2, my $buf, 4096
		690	or $cv->end;
		691	});
		692
		693	$cv->recv;
		694
		695	This works because for every event source (EOF on file handle), there is
		696	one call to C<begin>, so the condvar waits for all calls to C<end> before
		697	sending.
		698
		699	The ping example mentioned above is slightly more complicated, as the
		700	there are results to be passwd back, and the number of tasks that are
		701	begung can potentially be zero:
509		702
510	my $cv = AnyEvent->condvar;	703	my $cv = AnyEvent->condvar;
511		704
512	my %result;	705	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	706	$cv->begin (sub { $cv->send (\%result) });
…		…
533	loop, which serves two important purposes: first, it sets the callback	726	loop, which serves two important purposes: first, it sets the callback
534	to be called once the counter reaches C<0>, and second, it ensures that	727	to be called once the counter reaches C<0>, and second, it ensures that
535	C<send> is called even when C<no> hosts are being pinged (the loop	728	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	729	doesn't execute once).
537		730
538	This is the general pattern when you "fan out" into multiple subrequests:	731	This is the general pattern when you "fan out" into multiple (but
539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	732	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
540	is called at least once, and then, for each subrequest you start, call	733	the callback and ensure C<end> is called at least once, and then, for each
541	C<begin> and for each subrequest you finish, call C<end>.	734	subrequest you start, call C<begin> and for each subrequest you finish,
		735	call C<end>.
542		736
543	=back	737	=back
544		738
545	=head3 METHODS FOR CONSUMERS	739	=head3 METHODS FOR CONSUMERS
546		740
…		…
562	function will call C<croak>.	756	function will call C<croak>.
563		757
564	In list context, all parameters passed to C<send> will be returned,	758	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	759	in scalar context only the first one will be returned.
566		760
		761	Note that doing a blocking wait in a callback is not supported by any
		762	event loop, that is, recursive invocation of a blocking C<< ->recv
		763	>> is not allowed, and the C<recv> call will C<croak> if such a
		764	condition is detected. This condition can be slightly loosened by using
		765	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		766	any thread that doesn't run the event loop itself.
		767
567	Not all event models support a blocking wait - some die in that case	768	Not all event models support a blocking wait - some die in that case
568	(programs might want to do that to stay interactive), so I<if you are	769	(programs might want to do that to stay interactive), so I<if you are
569	using this from a module, never require a blocking wait>, but let the	770	using this from a module, never require a blocking wait>. Instead, let the
570	caller decide whether the call will block or not (for example, by coupling	771	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	772	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	773	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	774	while still supporting blocking waits if the caller so desires).
574		775
575	Another reason I<never> to C<< ->recv >> in a module is that you cannot
576	sensibly have two C<< ->recv >>'s in parallel, as that would require
577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
578	can supply.
579
580	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
581	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
582	versions and also integrates coroutines into AnyEvent, making blocking
583	C<< ->recv >> calls perfectly safe as long as they are done from another
584	coroutine (one that doesn't run the event loop).
585
586	You can ensure that C<< -recv >> never blocks by setting a callback and	776	You can ensure that C<< -recv >> never blocks by setting a callback and
587	only calling C<< ->recv >> from within that callback (or at a later	777	only calling C<< ->recv >> from within that callback (or at a later
588	time). This will work even when the event loop does not support blocking	778	time). This will work even when the event loop does not support blocking
589	waits otherwise.	779	waits otherwise.
590		780
591	=item $bool = $cv->ready	781	=item $bool = $cv->ready
592		782
593	Returns true when the condition is "true", i.e. whether C<send> or	783	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	784	C<croak> have been called.
595		785
596	=item $cb = $cv->cb ([new callback])	786	=item $cb = $cv->cb ($cb->($cv))
597		787
598	This is a mutator function that returns the callback set and optionally	788	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	789	replaces it before doing so.
600		790
601	The callback will be called when the condition becomes "true", i.e. when	791	The callback will be called when the condition becomes "true", i.e. when
…		…
603	variable itself. Calling C<recv> inside the callback or at any later time	793	variable itself. Calling C<recv> inside the callback or at any later time
604	is guaranteed not to block.	794	is guaranteed not to block.
605		795
606	=back	796	=back
607		797
		798	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		799
		800	The available backend classes are (every class has its own manpage):
		801
		802	=over 4
		803
		804	=item Backends that are autoprobed when no other event loop can be found.
		805
		806	EV is the preferred backend when no other event loop seems to be in
		807	use. If EV is not installed, then AnyEvent will try Event, and, failing
		808	that, will fall back to its own pure-perl implementation, which is
		809	available everywhere as it comes with AnyEvent itself.
		810
		811	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		812	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		813	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		814
		815	=item Backends that are transparently being picked up when they are used.
		816
		817	These will be used when they are currently loaded when the first watcher
		818	is created, in which case it is assumed that the application is using
		819	them. This means that AnyEvent will automatically pick the right backend
		820	when the main program loads an event module before anything starts to
		821	create watchers. Nothing special needs to be done by the main program.
		822
		823	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		824	AnyEvent::Impl::Tk based on Tk, very broken.
		825	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		826	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		827	AnyEvent::Impl::Irssi used when running within irssi.
		828
		829	=item Backends with special needs.
		830
		831	Qt requires the Qt::Application to be instantiated first, but will
		832	otherwise be picked up automatically. As long as the main program
		833	instantiates the application before any AnyEvent watchers are created,
		834	everything should just work.
		835
		836	AnyEvent::Impl::Qt based on Qt.
		837
		838	Support for IO::Async can only be partial, as it is too broken and
		839	architecturally limited to even support the AnyEvent API. It also
		840	is the only event loop that needs the loop to be set explicitly, so
		841	it can only be used by a main program knowing about AnyEvent. See
		842	L<AnyEvent::Impl::Async> for the gory details.
		843
		844	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		845
		846	=item Event loops that are indirectly supported via other backends.
		847
		848	Some event loops can be supported via other modules:
		849
		850	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		851
		852	B<WxWidgets> has no support for watching file handles. However, you can
		853	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		854	polls 20 times per second, which was considered to be too horrible to even
		855	consider for AnyEvent.
		856
		857	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		858	backend, so it can be supported through POE.
		859
		860	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		861	load L<POE> when detecting them, in the hope that POE will pick them up,
		862	in which case everything will be automatic.
		863
		864	=back
		865
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	866	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		867
		868	These are not normally required to use AnyEvent, but can be useful to
		869	write AnyEvent extension modules.
		870
610	=over 4	871	=over 4
611		872
612	=item $AnyEvent::MODEL	873	=item $AnyEvent::MODEL
613		874
614	Contains C<undef> until the first watcher is being created. Then it	875	Contains C<undef> until the first watcher is being created, before the
		876	backend has been autodetected.
		877
615	contains the event model that is being used, which is the name of the	878	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	879	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	880	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	881	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		882	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		883
641	=item AnyEvent::detect	884	=item AnyEvent::detect
642		885
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	886	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	887	if necessary. You should only call this function right before you would
645	have created an AnyEvent watcher anyway, that is, as late as possible at	888	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	889	runtime, and not e.g. while initialising of your module.
		890
		891	If you need to do some initialisation before AnyEvent watchers are
		892	created, use C<post_detect>.
647		893
648	=item $guard = AnyEvent::post_detect { BLOCK }	894	=item $guard = AnyEvent::post_detect { BLOCK }
649		895
650	Arranges for the code block to be executed as soon as the event model is	896	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	897	autodetected (or immediately if this has already happened).
652		898
		899	The block will be executed I<after> the actual backend has been detected
		900	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		901	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		902	other initialisations - see the sources of L<AnyEvent::Strict> or
		903	L<AnyEvent::AIO> to see how this is used.
		904
		905	The most common usage is to create some global watchers, without forcing
		906	event module detection too early, for example, L<AnyEvent::AIO> creates
		907	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		908	avoid autodetecting the event module at load time.
		909
653	If called in scalar or list context, then it creates and returns an object	910	If called in scalar or list context, then it creates and returns an object
654	that automatically removes the callback again when it is destroyed. See	911	that automatically removes the callback again when it is destroyed (or
		912	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	913	a case where this is useful.
		914
		915	Example: Create a watcher for the IO::AIO module and store it in
		916	C<$WATCHER>. Only do so after the event loop is initialised, though.
		917
		918	our WATCHER;
		919
		920	my $guard = AnyEvent::post_detect {
		921	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		922	};
		923
		924	# the ||= is important in case post_detect immediately runs the block,
		925	# as to not clobber the newly-created watcher. assigning both watcher and
		926	# post_detect guard to the same variable has the advantage of users being
		927	# able to just C<undef $WATCHER> if the watcher causes them grief.
		928
		929	$WATCHER ||= $guard;
656		930
657	=item @AnyEvent::post_detect	931	=item @AnyEvent::post_detect
658		932
659	If there are any code references in this array (you can C<push> to it	933	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	934	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	935	the event loop has been chosen.
662		936
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	937	You should check C<$AnyEvent::MODEL> before adding to this array, though:
664	if it contains a true value then the event loop has already been detected,	938	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	939	array will be ignored.
666		940
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	941	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		942	it,as it takes care of these details.
		943
		944	This variable is mainly useful for modules that can do something useful
		945	when AnyEvent is used and thus want to know when it is initialised, but do
		946	not need to even load it by default. This array provides the means to hook
		947	into AnyEvent passively, without loading it.
668		948
669	=back	949	=back
670		950
671	=head1 WHAT TO DO IN A MODULE	951	=head1 WHAT TO DO IN A MODULE
672		952
…		…
727		1007
728		1008
729	=head1 OTHER MODULES	1009	=head1 OTHER MODULES
730		1010
731	The following is a non-exhaustive list of additional modules that use	1011	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1012	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
733	in the same program. Some of the modules come with AnyEvent, some are	1013	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1014	come with AnyEvent, most are available via CPAN.
735		1015
736	=over 4	1016	=over 4
737		1017
738	=item L<AnyEvent::Util>	1018	=item L<AnyEvent::Util>
739		1019
740	Contains various utility functions that replace often-used but blocking	1020	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1021	functions such as C<inet_aton> by event-/callback-based versions.
742
743	=item L<AnyEvent::Handle>
744
745	Provide read and write buffers and manages watchers for reads and writes.
746		1022
747	=item L<AnyEvent::Socket>	1023	=item L<AnyEvent::Socket>
748		1024
749	Provides various utility functions for (internet protocol) sockets,	1025	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1026	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1027	connections or tcp servers, with IPv6 and SRV record support and more.
752		1028
		1029	=item L<AnyEvent::Handle>
		1030
		1031	Provide read and write buffers, manages watchers for reads and writes,
		1032	supports raw and formatted I/O, I/O queued and fully transparent and
		1033	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1034
753	=item L<AnyEvent::DNS>	1035	=item L<AnyEvent::DNS>
754		1036
755	Provides rich asynchronous DNS resolver capabilities.	1037	Provides rich asynchronous DNS resolver capabilities.
756		1038
757	=item L<AnyEvent::HTTP>	1039	=item L<AnyEvent::HTTP>
…		…
767		1049
768	The fastest ping in the west.	1050	The fastest ping in the west.
769		1051
770	=item L<AnyEvent::DBI>	1052	=item L<AnyEvent::DBI>
771		1053
772	Executes DBI requests asynchronously in a proxy process.	1054	Executes L<DBI> requests asynchronously in a proxy process.
773		1055
		1056	=item L<AnyEvent::AIO>
		1057
		1058	Truly asynchronous I/O, should be in the toolbox of every event
		1059	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1060	together.
		1061
		1062	=item L<AnyEvent::BDB>
		1063
		1064	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1065	L<BDB> and AnyEvent together.
		1066
		1067	=item L<AnyEvent::GPSD>
		1068
		1069	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1070
774	=item L<Net::IRC3>	1071	=item L<AnyEvent::IRC>
775		1072
776	AnyEvent based IRC client module family.	1073	AnyEvent based IRC client module family (replacing the older Net::IRC3).
777		1074
778	=item L<Net::XMPP2>	1075	=item L<AnyEvent::XMPP>
779		1076
780	AnyEvent based XMPP (Jabber protocol) module family.	1077	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1078	Net::XMPP2>.
		1079
		1080	=item L<AnyEvent::IGS>
		1081
		1082	A non-blocking interface to the Internet Go Server protocol (used by
		1083	L<App::IGS>).
781		1084
782	=item L<Net::FCP>	1085	=item L<Net::FCP>
783		1086
784	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1087	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
785	of AnyEvent.	1088	of AnyEvent.
…		…
790		1093
791	=item L<Coro>	1094	=item L<Coro>
792		1095
793	Has special support for AnyEvent via L<Coro::AnyEvent>.	1096	Has special support for AnyEvent via L<Coro::AnyEvent>.
794		1097
795	=item L<AnyEvent::AIO>, L<IO::AIO>
796
797	Truly asynchronous I/O, should be in the toolbox of every event
798	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
799	together.
800
801	=item L<AnyEvent::BDB>, L<BDB>
802
803	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
804	IO::AIO and AnyEvent together.
805
806	=item L<IO::Lambda>
807
808	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
809
810	=back	1098	=back
811		1099
812	=cut	1100	=cut
813		1101
814	package AnyEvent;	1102	package AnyEvent;
815		1103
		1104	# basically a tuned-down version of common::sense
		1105	sub common_sense {
816	no warnings;	1106	# no warnings
817	use strict;	1107	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1108	# use strict vars subs
		1109	$^H |= 0x00000600;
		1110	}
818		1111
		1112	BEGIN { AnyEvent::common_sense }
		1113
819	use Carp;	1114	use Carp ();
820		1115
821	our $VERSION = 4.151;	1116	our $VERSION = 4.881;
822	our $MODEL;	1117	our $MODEL;
823		1118
824	our $AUTOLOAD;	1119	our $AUTOLOAD;
825	our @ISA;	1120	our @ISA;
826		1121
827	our @REGISTRY;	1122	our @REGISTRY;
828		1123
829	our $WIN32;	1124	our $WIN32;
830		1125
		1126	our $VERBOSE;
		1127
831	BEGIN {	1128	BEGIN {
832	my $win32 = ! ! ($^O =~ /mswin32/i);	1129	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
833	eval "sub WIN32(){ $win32 }";	1130	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
834	}
835		1131
		1132	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1133	if ${^TAINT};
		1134
836	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1135	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1136
		1137	}
		1138
		1139	our $MAX_SIGNAL_LATENCY = 10;
837		1140
838	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1141	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
839		1142
840	{	1143	{
841	my $idx;	1144	my $idx;
…		…
843	for reverse split /\s*,\s*/,	1146	for reverse split /\s*,\s*/,
844	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1147	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
845	}	1148	}
846		1149
847	my @models = (	1150	my @models = (
848	[EV:: => AnyEvent::Impl::EV::],	1151	[EV:: => AnyEvent::Impl::EV:: , 1],
849	[Event:: => AnyEvent::Impl::Event::],	1152	[Event:: => AnyEvent::Impl::Event::, 1],
850	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1153	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
851	# everything below here will not be autoprobed	1154	# everything below here will not (normally) be autoprobed
852	# as the pureperl backend should work everywhere	1155	# as the pureperl backend should work everywhere
853	# and is usually faster	1156	# and is usually faster
		1157	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1158	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1159	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
854	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1160	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
855	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
856	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
857	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1161	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
858	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1162	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
859	[Wx:: => AnyEvent::Impl::POE::],	1163	[Wx:: => AnyEvent::Impl::POE::],
860	[Prima:: => AnyEvent::Impl::POE::],	1164	[Prima:: => AnyEvent::Impl::POE::],
		1165	# IO::Async is just too broken - we would need workarounds for its
		1166	# byzantine signal and broken child handling, among others.
		1167	# IO::Async is rather hard to detect, as it doesn't have any
		1168	# obvious default class.
		1169	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1170	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1171	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
861	);	1172	);
862		1173
863	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1174	our %method = map +($_ => 1),
		1175	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
864		1176
865	our @post_detect;	1177	our @post_detect;
866		1178
867	sub post_detect(&) {	1179	sub post_detect(&) {
868	my ($cb) = @_;	1180	my ($cb) = @_;
869		1181
870	if ($MODEL) {	1182	if ($MODEL) {
871	$cb->();	1183	$cb->();
872		1184
873	1	1185	undef
874	} else {	1186	} else {
875	push @post_detect, $cb;	1187	push @post_detect, $cb;
876		1188
877	defined wantarray	1189	defined wantarray
878	? bless \$cb, "AnyEvent::Util::PostDetect"	1190	? bless \$cb, "AnyEvent::Util::postdetect"
879	: ()	1191	: ()
880	}	1192	}
881	}	1193	}
882		1194
883	sub AnyEvent::Util::PostDetect::DESTROY {	1195	sub AnyEvent::Util::postdetect::DESTROY {
884	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1196	@post_detect = grep $_ != ${$_[0]}, @post_detect;
885	}	1197	}
886		1198
887	sub detect() {	1199	sub detect() {
888	unless ($MODEL) {	1200	unless ($MODEL) {
889	no strict 'refs';
890	local $SIG{__DIE__};	1201	local $SIG{__DIE__};
891		1202
892	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1203	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
893	my $model = "AnyEvent::Impl::$1";	1204	my $model = "AnyEvent::Impl::$1";
894	if (eval "require $model") {	1205	if (eval "require $model") {
895	$MODEL = $model;	1206	$MODEL = $model;
896	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1207	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
897	} else {	1208	} else {
898	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1209	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
899	}	1210	}
900	}	1211	}
901		1212
902	# check for already loaded models	1213	# check for already loaded models
903	unless ($MODEL) {	1214	unless ($MODEL) {
904	for (@REGISTRY, @models) {	1215	for (@REGISTRY, @models) {
905	my ($package, $model) = @$_;	1216	my ($package, $model) = @$_;
906	if (${"$package\::VERSION"} > 0) {	1217	if (${"$package\::VERSION"} > 0) {
907	if (eval "require $model") {	1218	if (eval "require $model") {
908	$MODEL = $model;	1219	$MODEL = $model;
909	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1220	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
910	last;	1221	last;
911	}	1222	}
912	}	1223	}
913	}	1224	}
914		1225
915	unless ($MODEL) {	1226	unless ($MODEL) {
916	# try to load a model	1227	# try to autoload a model
917
918	for (@REGISTRY, @models) {	1228	for (@REGISTRY, @models) {
919	my ($package, $model) = @$_;	1229	my ($package, $model, $autoload) = @$_;
		1230	if (
		1231	$autoload
920	if (eval "require $package"	1232	and eval "require $package"
921	and ${"$package\::VERSION"} > 0	1233	and ${"$package\::VERSION"} > 0
922	and eval "require $model") {	1234	and eval "require $model"
		1235	) {
923	$MODEL = $model;	1236	$MODEL = $model;
924	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1237	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
925	last;	1238	last;
926	}	1239	}
927	}	1240	}
928		1241
929	$MODEL	1242	$MODEL
930	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1243	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
931	}	1244	}
932	}	1245	}
933		1246
		1247	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1248
934	unshift @ISA, $MODEL;	1249	unshift @ISA, $MODEL;
935	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1250
		1251	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
936		1252
937	(shift @post_detect)->() while @post_detect;	1253	(shift @post_detect)->() while @post_detect;
938	}	1254	}
939		1255
940	$MODEL	1256	$MODEL
…		…
942		1258
943	sub AUTOLOAD {	1259	sub AUTOLOAD {
944	(my $func = $AUTOLOAD) =~ s/.*://;	1260	(my $func = $AUTOLOAD) =~ s/.*://;
945		1261
946	$method{$func}	1262	$method{$func}
947	or croak "$func: not a valid method for AnyEvent objects";	1263	or Carp::croak "$func: not a valid method for AnyEvent objects";
948		1264
949	detect unless $MODEL;	1265	detect unless $MODEL;
950		1266
951	my $class = shift;	1267	my $class = shift;
952	$class->$func (@_);	1268	$class->$func (@_);
953	}	1269	}
954		1270
		1271	# utility function to dup a filehandle. this is used by many backends
		1272	# to support binding more than one watcher per filehandle (they usually
		1273	# allow only one watcher per fd, so we dup it to get a different one).
		1274	sub _dupfh($$;$$) {
		1275	my ($poll, $fh, $r, $w) = @_;
		1276
		1277	# cygwin requires the fh mode to be matching, unix doesn't
		1278	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1279
		1280	open my $fh2, $mode, $fh
		1281	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1282
		1283	# we assume CLOEXEC is already set by perl in all important cases
		1284
		1285	($fh2, $rw)
		1286	}
		1287
955	package AnyEvent::Base;	1288	package AnyEvent::Base;
956		1289
957	# default implementation for now and time	1290	# default implementations for many methods
958		1291
959	use Time::HiRes ();	1292	sub _time {
		1293	# probe for availability of Time::HiRes
		1294	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1295	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1296	*_time = \&Time::HiRes::time;
		1297	# if (eval "use POSIX (); (POSIX::times())...
		1298	} else {
		1299	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1300	*_time = sub { time }; # epic fail
		1301	}
960		1302
961	sub time { Time::HiRes::time }	1303	&_time
962	sub now { Time::HiRes::time }	1304	}
		1305
		1306	sub time { _time }
		1307	sub now { _time }
		1308	sub now_update { }
963		1309
964	# default implementation for ->condvar	1310	# default implementation for ->condvar
965		1311
966	sub condvar {	1312	sub condvar {
967	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1313	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
968	}	1314	}
969		1315
970	# default implementation for ->signal	1316	# default implementation for ->signal
971		1317
972	our %SIG_CB;	1318	our $HAVE_ASYNC_INTERRUPT;
		1319
		1320	sub _have_async_interrupt() {
		1321	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1322	&& eval "use Async::Interrupt 1.0 (); 1")
		1323	unless defined $HAVE_ASYNC_INTERRUPT;
		1324
		1325	$HAVE_ASYNC_INTERRUPT
		1326	}
		1327
		1328	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1329	our (%SIG_ASY, %SIG_ASY_W);
		1330	our ($SIG_COUNT, $SIG_TW);
		1331
		1332	sub _signal_exec {
		1333	$HAVE_ASYNC_INTERRUPT
		1334	? $SIGPIPE_R->drain
		1335	: sysread $SIGPIPE_R, my $dummy, 9;
		1336
		1337	while (%SIG_EV) {
		1338	for (keys %SIG_EV) {
		1339	delete $SIG_EV{$_};
		1340	$_->() for values %{ $SIG_CB{$_} || {} };
		1341	}
		1342	}
		1343	}
		1344
		1345	# install a dummy wakeup watcher to reduce signal catching latency
		1346	sub _sig_add() {
		1347	unless ($SIG_COUNT++) {
		1348	# try to align timer on a full-second boundary, if possible
		1349	my $NOW = AnyEvent->now;
		1350
		1351	$SIG_TW = AnyEvent->timer (
		1352	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1353	interval => $MAX_SIGNAL_LATENCY,
		1354	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1355	);
		1356	}
		1357	}
		1358
		1359	sub _sig_del {
		1360	undef $SIG_TW
		1361	unless --$SIG_COUNT;
		1362	}
		1363
		1364	our $_sig_name_init; $_sig_name_init = sub {
		1365	eval q{ # poor man's autoloading
		1366	undef $_sig_name_init;
		1367
		1368	if (_have_async_interrupt) {
		1369	*sig2num = \&Async::Interrupt::sig2num;
		1370	*sig2name = \&Async::Interrupt::sig2name;
		1371	} else {
		1372	require Config;
		1373
		1374	my %signame2num;
		1375	@signame2num{ split ' ', $Config::Config{sig_name} }
		1376	= split ' ', $Config::Config{sig_num};
		1377
		1378	my @signum2name;
		1379	@signum2name[values %signame2num] = keys %signame2num;
		1380
		1381	*sig2num = sub($) {
		1382	$_[0] > 0 ? shift : $signame2num{+shift}
		1383	};
		1384	*sig2name = sub ($) {
		1385	$_[0] > 0 ? $signum2name[+shift] : shift
		1386	};
		1387	}
		1388	};
		1389	die if $@;
		1390	};
		1391
		1392	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1393	sub sig2name($) { &$_sig_name_init; &sig2name }
973		1394
974	sub signal {	1395	sub signal {
		1396	eval q{ # poor man's autoloading {}
		1397	# probe for availability of Async::Interrupt
		1398	if (_have_async_interrupt) {
		1399	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1400
		1401	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1402	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1403
		1404	} else {
		1405	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1406
		1407	require Fcntl;
		1408
		1409	if (AnyEvent::WIN32) {
		1410	require AnyEvent::Util;
		1411
		1412	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1413	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1414	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1415	} else {
		1416	pipe $SIGPIPE_R, $SIGPIPE_W;
		1417	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1418	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1419
		1420	# not strictly required, as $^F is normally 2, but let's make sure...
		1421	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1422	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1423	}
		1424
		1425	$SIGPIPE_R
		1426	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1427
		1428	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1429	}
		1430
		1431	*signal = sub {
975	my (undef, %arg) = @_;	1432	my (undef, %arg) = @_;
976		1433
977	my $signal = uc $arg{signal}	1434	my $signal = uc $arg{signal}
978	or Carp::croak "required option 'signal' is missing";	1435	or Carp::croak "required option 'signal' is missing";
979		1436
		1437	if ($HAVE_ASYNC_INTERRUPT) {
		1438	# async::interrupt
		1439
		1440	$signal = sig2num $signal;
980	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1441	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1442
		1443	$SIG_ASY{$signal} ||= new Async::Interrupt
		1444	cb => sub { undef $SIG_EV{$signal} },
		1445	signal => $signal,
		1446	pipe => [$SIGPIPE_R->filenos],
		1447	pipe_autodrain => 0,
		1448	;
		1449
		1450	} else {
		1451	# pure perl
		1452
		1453	# AE::Util has been loaded in signal
		1454	$signal = sig2name $signal;
		1455	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1456
981	$SIG{$signal} ||= sub {	1457	$SIG{$signal} ||= sub {
982	$_->() for values %{ $SIG_CB{$signal} || {} };	1458	local $!;
		1459	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1460	undef $SIG_EV{$signal};
		1461	};
		1462
		1463	# can't do signal processing without introducing races in pure perl,
		1464	# so limit the signal latency.
		1465	_sig_add;
		1466	}
		1467
		1468	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1469	};
		1470
		1471	*AnyEvent::Base::signal::DESTROY = sub {
		1472	my ($signal, $cb) = @{$_[0]};
		1473
		1474	_sig_del;
		1475
		1476	delete $SIG_CB{$signal}{$cb};
		1477
		1478	$HAVE_ASYNC_INTERRUPT
		1479	? delete $SIG_ASY{$signal}
		1480	: # delete doesn't work with older perls - they then
		1481	# print weird messages, or just unconditionally exit
		1482	# instead of getting the default action.
		1483	undef $SIG{$signal}
		1484	unless keys %{ $SIG_CB{$signal} };
		1485	};
983	};	1486	};
984		1487	die if $@;
985	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1488	&signal
986	}
987
988	sub AnyEvent::Base::Signal::DESTROY {
989	my ($signal, $cb) = @{$_[0]};
990
991	delete $SIG_CB{$signal}{$cb};
992
993	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
994	}	1489	}
995		1490
996	# default implementation for ->child	1491	# default implementation for ->child
997		1492
998	our %PID_CB;	1493	our %PID_CB;
999	our $CHLD_W;	1494	our $CHLD_W;
1000	our $CHLD_DELAY_W;	1495	our $CHLD_DELAY_W;
1001	our $PID_IDLE;
1002	our $WNOHANG;	1496	our $WNOHANG;
1003		1497
1004	sub _child_wait {	1498	sub _emit_childstatus($$) {
1005	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1499	my (undef, $rpid, $rstatus) = @_;
		1500
		1501	$_->($rpid, $rstatus)
1006	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1502	for values %{ $PID_CB{$rpid} || {} },
1007	(values %{ $PID_CB{0} || {} });	1503	values %{ $PID_CB{0} || {} };
1008	}
1009
1010	undef $PID_IDLE;
1011	}	1504	}
1012		1505
1013	sub _sigchld {	1506	sub _sigchld {
1014	# make sure we deliver these changes "synchronous" with the event loop.	1507	my $pid;
1015	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1508
1016	undef $CHLD_DELAY_W;	1509	AnyEvent->_emit_childstatus ($pid, $?)
1017	&_child_wait;	1510	while ($pid = waitpid -1, $WNOHANG) > 0;
1018	});
1019	}	1511	}
1020		1512
1021	sub child {	1513	sub child {
1022	my (undef, %arg) = @_;	1514	my (undef, %arg) = @_;
1023		1515
1024	defined (my $pid = $arg{pid} + 0)	1516	defined (my $pid = $arg{pid} + 0)
1025	or Carp::croak "required option 'pid' is missing";	1517	or Carp::croak "required option 'pid' is missing";
1026		1518
1027	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1519	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1028		1520
1029	unless ($WNOHANG) {	1521	# WNOHANG is almost cetrainly 1 everywhere
		1522	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1523	? 1
1030	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1524	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1031	}
1032		1525
1033	unless ($CHLD_W) {	1526	unless ($CHLD_W) {
1034	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1527	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1035	# child could be a zombie already, so make at least one round	1528	# child could be a zombie already, so make at least one round
1036	&_sigchld;	1529	&_sigchld;
1037	}	1530	}
1038		1531
1039	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1532	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1040	}	1533	}
1041		1534
1042	sub AnyEvent::Base::Child::DESTROY {	1535	sub AnyEvent::Base::child::DESTROY {
1043	my ($pid, $cb) = @{$_[0]};	1536	my ($pid, $cb) = @{$_[0]};
1044		1537
1045	delete $PID_CB{$pid}{$cb};	1538	delete $PID_CB{$pid}{$cb};
1046	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1539	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1047		1540
1048	undef $CHLD_W unless keys %PID_CB;	1541	undef $CHLD_W unless keys %PID_CB;
1049	}	1542	}
1050		1543
		1544	# idle emulation is done by simply using a timer, regardless
		1545	# of whether the process is idle or not, and not letting
		1546	# the callback use more than 50% of the time.
		1547	sub idle {
		1548	my (undef, %arg) = @_;
		1549
		1550	my ($cb, $w, $rcb) = $arg{cb};
		1551
		1552	$rcb = sub {
		1553	if ($cb) {
		1554	$w = _time;
		1555	&$cb;
		1556	$w = _time - $w;
		1557
		1558	# never use more then 50% of the time for the idle watcher,
		1559	# within some limits
		1560	$w = 0.0001 if $w < 0.0001;
		1561	$w = 5 if $w > 5;
		1562
		1563	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1564	} else {
		1565	# clean up...
		1566	undef $w;
		1567	undef $rcb;
		1568	}
		1569	};
		1570
		1571	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1572
		1573	bless \\$cb, "AnyEvent::Base::idle"
		1574	}
		1575
		1576	sub AnyEvent::Base::idle::DESTROY {
		1577	undef $${$_[0]};
		1578	}
		1579
1051	package AnyEvent::CondVar;	1580	package AnyEvent::CondVar;
1052		1581
1053	our @ISA = AnyEvent::CondVar::Base::;	1582	our @ISA = AnyEvent::CondVar::Base::;
1054		1583
1055	package AnyEvent::CondVar::Base;	1584	package AnyEvent::CondVar::Base;
1056		1585
1057	use overload	1586	#use overload
1058	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1587	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1059	fallback => 1;	1588	# fallback => 1;
		1589
		1590	# save 300+ kilobytes by dirtily hardcoding overloading
		1591	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1592	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1593	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1594	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1595
		1596	our $WAITING;
1060		1597
1061	sub _send {	1598	sub _send {
1062	# nop	1599	# nop
1063	}	1600	}
1064		1601
…		…
1077	sub ready {	1614	sub ready {
1078	$_[0]{_ae_sent}	1615	$_[0]{_ae_sent}
1079	}	1616	}
1080		1617
1081	sub _wait {	1618	sub _wait {
		1619	$WAITING
		1620	and !$_[0]{_ae_sent}
		1621	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1622
		1623	local $WAITING = 1;
1082	AnyEvent->one_event while !$_[0]{_ae_sent};	1624	AnyEvent->one_event while !$_[0]{_ae_sent};
1083	}	1625	}
1084		1626
1085	sub recv {	1627	sub recv {
1086	$_[0]->_wait;	1628	$_[0]->_wait;
…		…
1105	}	1647	}
1106		1648
1107	# undocumented/compatibility with pre-3.4	1649	# undocumented/compatibility with pre-3.4
1108	*broadcast = \&send;	1650	*broadcast = \&send;
1109	*wait = \&_wait;	1651	*wait = \&_wait;
		1652
		1653	#############################################################################
		1654	# "new" API, currently only emulation of it
		1655	#############################################################################
		1656
		1657	package AE;
		1658
		1659	sub io($$$) {
		1660	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1661	}
		1662
		1663	sub timer($$$) {
		1664	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1665	}
		1666
		1667	sub signal($$) {
		1668	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1669	}
		1670
		1671	sub child($$) {
		1672	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1673	}
		1674
		1675	sub idle($) {
		1676	AnyEvent->idle (cb => $_[0]);
		1677	}
		1678
		1679	sub cv() {
		1680	AnyEvent->condvar
		1681	}
		1682
		1683	sub now() {
		1684	AnyEvent->now
		1685	}
		1686
		1687	sub now_update() {
		1688	AnyEvent->now_update
		1689	}
		1690
		1691	sub time() {
		1692	AnyEvent->time
		1693	}
		1694
		1695	=head1 ERROR AND EXCEPTION HANDLING
		1696
		1697	In general, AnyEvent does not do any error handling - it relies on the
		1698	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1699	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1700	checking of all AnyEvent methods, however, which is highly useful during
		1701	development.
		1702
		1703	As for exception handling (i.e. runtime errors and exceptions thrown while
		1704	executing a callback), this is not only highly event-loop specific, but
		1705	also not in any way wrapped by this module, as this is the job of the main
		1706	program.
		1707
		1708	The pure perl event loop simply re-throws the exception (usually
		1709	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1710	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1711	so on.
		1712
		1713	=head1 ENVIRONMENT VARIABLES
		1714
		1715	The following environment variables are used by this module or its
		1716	submodules.
		1717
		1718	Note that AnyEvent will remove I<all> environment variables starting with
		1719	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1720	enabled.
		1721
		1722	=over 4
		1723
		1724	=item C<PERL_ANYEVENT_VERBOSE>
		1725
		1726	By default, AnyEvent will be completely silent except in fatal
		1727	conditions. You can set this environment variable to make AnyEvent more
		1728	talkative.
		1729
		1730	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1731	conditions, such as not being able to load the event model specified by
		1732	C<PERL_ANYEVENT_MODEL>.
		1733
		1734	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1735	model it chooses.
		1736
		1737	When set to C<8> or higher, then AnyEvent will report extra information on
		1738	which optional modules it loads and how it implements certain features.
		1739
		1740	=item C<PERL_ANYEVENT_STRICT>
		1741
		1742	AnyEvent does not do much argument checking by default, as thorough
		1743	argument checking is very costly. Setting this variable to a true value
		1744	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1745	check the arguments passed to most method calls. If it finds any problems,
		1746	it will croak.
		1747
		1748	In other words, enables "strict" mode.
		1749
		1750	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1751	>>, it is definitely recommended to keep it off in production. Keeping
		1752	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1753	can be very useful, however.
		1754
		1755	=item C<PERL_ANYEVENT_MODEL>
		1756
		1757	This can be used to specify the event model to be used by AnyEvent, before
		1758	auto detection and -probing kicks in. It must be a string consisting
		1759	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1760	and the resulting module name is loaded and if the load was successful,
		1761	used as event model. If it fails to load AnyEvent will proceed with
		1762	auto detection and -probing.
		1763
		1764	This functionality might change in future versions.
		1765
		1766	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1767	could start your program like this:
		1768
		1769	PERL_ANYEVENT_MODEL=Perl perl ...
		1770
		1771	=item C<PERL_ANYEVENT_PROTOCOLS>
		1772
		1773	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1774	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1775	of auto probing).
		1776
		1777	Must be set to a comma-separated list of protocols or address families,
		1778	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1779	used, and preference will be given to protocols mentioned earlier in the
		1780	list.
		1781
		1782	This variable can effectively be used for denial-of-service attacks
		1783	against local programs (e.g. when setuid), although the impact is likely
		1784	small, as the program has to handle conenction and other failures anyways.
		1785
		1786	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1787	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1788	- only support IPv4, never try to resolve or contact IPv6
		1789	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1790	IPv6, but prefer IPv6 over IPv4.
		1791
		1792	=item C<PERL_ANYEVENT_EDNS0>
		1793
		1794	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1795	for DNS. This extension is generally useful to reduce DNS traffic, but
		1796	some (broken) firewalls drop such DNS packets, which is why it is off by
		1797	default.
		1798
		1799	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1800	EDNS0 in its DNS requests.
		1801
		1802	=item C<PERL_ANYEVENT_MAX_FORKS>
		1803
		1804	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1805	will create in parallel.
		1806
		1807	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1808
		1809	The default value for the C<max_outstanding> parameter for the default DNS
		1810	resolver - this is the maximum number of parallel DNS requests that are
		1811	sent to the DNS server.
		1812
		1813	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1814
		1815	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1816	configuration) in the default resolver. When set to the empty string, no
		1817	default config will be used.
		1818
		1819	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1820
		1821	When neither C<ca_file> nor C<ca_path> was specified during
		1822	L<AnyEvent::TLS> context creation, and either of these environment
		1823	variables exist, they will be used to specify CA certificate locations
		1824	instead of a system-dependent default.
		1825
		1826	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1827
		1828	When these are set to C<1>, then the respective modules are not
		1829	loaded. Mostly good for testing AnyEvent itself.
		1830
		1831	=back
1110		1832
1111	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1833	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1112		1834
1113	This is an advanced topic that you do not normally need to use AnyEvent in	1835	This is an advanced topic that you do not normally need to use AnyEvent in
1114	a module. This section is only of use to event loop authors who want to	1836	a module. This section is only of use to event loop authors who want to
…		…
1148		1870
1149	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1871	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1150	condition variables: code blocking while waiting for a condition will	1872	condition variables: code blocking while waiting for a condition will
1151	C<die>. This still works with most modules/usages, and blocking calls must	1873	C<die>. This still works with most modules/usages, and blocking calls must
1152	not be done in an interactive application, so it makes sense.	1874	not be done in an interactive application, so it makes sense.
1153
1154	=head1 ENVIRONMENT VARIABLES
1155
1156	The following environment variables are used by this module:
1157
1158	=over 4
1159
1160	=item C<PERL_ANYEVENT_VERBOSE>
1161
1162	By default, AnyEvent will be completely silent except in fatal
1163	conditions. You can set this environment variable to make AnyEvent more
1164	talkative.
1165
1166	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1167	conditions, such as not being able to load the event model specified by
1168	C<PERL_ANYEVENT_MODEL>.
1169
1170	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1171	model it chooses.
1172
1173	=item C<PERL_ANYEVENT_MODEL>
1174
1175	This can be used to specify the event model to be used by AnyEvent, before
1176	auto detection and -probing kicks in. It must be a string consisting
1177	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1178	and the resulting module name is loaded and if the load was successful,
1179	used as event model. If it fails to load AnyEvent will proceed with
1180	auto detection and -probing.
1181
1182	This functionality might change in future versions.
1183
1184	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1185	could start your program like this:
1186
1187	PERL_ANYEVENT_MODEL=Perl perl ...
1188
1189	=item C<PERL_ANYEVENT_PROTOCOLS>
1190
1191	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1192	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1193	of auto probing).
1194
1195	Must be set to a comma-separated list of protocols or address families,
1196	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1197	used, and preference will be given to protocols mentioned earlier in the
1198	list.
1199
1200	This variable can effectively be used for denial-of-service attacks
1201	against local programs (e.g. when setuid), although the impact is likely
1202	small, as the program has to handle connection errors already-
1203
1204	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1205	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1206	- only support IPv4, never try to resolve or contact IPv6
1207	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1208	IPv6, but prefer IPv6 over IPv4.
1209
1210	=item C<PERL_ANYEVENT_EDNS0>
1211
1212	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1213	for DNS. This extension is generally useful to reduce DNS traffic, but
1214	some (broken) firewalls drop such DNS packets, which is why it is off by
1215	default.
1216
1217	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1218	EDNS0 in its DNS requests.
1219
1220	=item C<PERL_ANYEVENT_MAX_FORKS>
1221
1222	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1223	will create in parallel.
1224
1225	=back
1226		1875
1227	=head1 EXAMPLE PROGRAM	1876	=head1 EXAMPLE PROGRAM
1228		1877
1229	The following program uses an I/O watcher to read data from STDIN, a timer	1878	The following program uses an I/O watcher to read data from STDIN, a timer
1230	to display a message once per second, and a condition variable to quit the	1879	to display a message once per second, and a condition variable to quit the
…		…
1424	watcher.	2073	watcher.
1425		2074
1426	=head3 Results	2075	=head3 Results
1427		2076
1428	name watchers bytes create invoke destroy comment	2077	name watchers bytes create invoke destroy comment
1429	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2078	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1430	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2079	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1431	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2080	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1432	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2081	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1433	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2082	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1434	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2083	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2084	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2085	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1435	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2086	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1436	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2087	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1437	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2088	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1438	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2089	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1439		2090
1440	=head3 Discussion	2091	=head3 Discussion
1441		2092
1442	The benchmark does I<not> measure scalability of the event loop very	2093	The benchmark does I<not> measure scalability of the event loop very
1443	well. For example, a select-based event loop (such as the pure perl one)	2094	well. For example, a select-based event loop (such as the pure perl one)
…		…
1468	performance becomes really bad with lots of file descriptors (and few of	2119	performance becomes really bad with lots of file descriptors (and few of
1469	them active), of course, but this was not subject of this benchmark.	2120	them active), of course, but this was not subject of this benchmark.
1470		2121
1471	The C<Event> module has a relatively high setup and callback invocation	2122	The C<Event> module has a relatively high setup and callback invocation
1472	cost, but overall scores in on the third place.	2123	cost, but overall scores in on the third place.
		2124
		2125	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2126	when using its pure perl backend.
1473		2127
1474	C<Glib>'s memory usage is quite a bit higher, but it features a	2128	C<Glib>'s memory usage is quite a bit higher, but it features a
1475	faster callback invocation and overall ends up in the same class as	2129	faster callback invocation and overall ends up in the same class as
1476	C<Event>. However, Glib scales extremely badly, doubling the number of	2130	C<Event>. However, Glib scales extremely badly, doubling the number of
1477	watchers increases the processing time by more than a factor of four,	2131	watchers increases the processing time by more than a factor of four,
…		…
1555	it to another server. This includes deleting the old timeout and creating	2209	it to another server. This includes deleting the old timeout and creating
1556	a new one that moves the timeout into the future.	2210	a new one that moves the timeout into the future.
1557		2211
1558	=head3 Results	2212	=head3 Results
1559		2213
1560	name sockets create request	2214	name sockets create request
1561	EV 20000 69.01 11.16	2215	EV 20000 69.01 11.16
1562	Perl 20000 73.32 35.87	2216	Perl 20000 73.32 35.87
		2217	IOAsync 20000 157.00 98.14 epoll
		2218	IOAsync 20000 159.31 616.06 poll
1563	Event 20000 212.62 257.32	2219	Event 20000 212.62 257.32
1564	Glib 20000 651.16 1896.30	2220	Glib 20000 651.16 1896.30
1565	POE 20000 349.67 12317.24 uses POE::Loop::Event	2221	POE 20000 349.67 12317.24 uses POE::Loop::Event
1566		2222
1567	=head3 Discussion	2223	=head3 Discussion
1568		2224
1569	This benchmark I<does> measure scalability and overall performance of the	2225	This benchmark I<does> measure scalability and overall performance of the
1570	particular event loop.	2226	particular event loop.
…		…
1572	EV is again fastest. Since it is using epoll on my system, the setup time	2228	EV is again fastest. Since it is using epoll on my system, the setup time
1573	is relatively high, though.	2229	is relatively high, though.
1574		2230
1575	Perl surprisingly comes second. It is much faster than the C-based event	2231	Perl surprisingly comes second. It is much faster than the C-based event
1576	loops Event and Glib.	2232	loops Event and Glib.
		2233
		2234	IO::Async performs very well when using its epoll backend, and still quite
		2235	good compared to Glib when using its pure perl backend.
1577		2236
1578	Event suffers from high setup time as well (look at its code and you will	2237	Event suffers from high setup time as well (look at its code and you will
1579	understand why). Callback invocation also has a high overhead compared to	2238	understand why). Callback invocation also has a high overhead compared to
1580	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2239	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1581	uses select or poll in basically all documented configurations.	2240	uses select or poll in basically all documented configurations.
…		…
1644	=item * C-based event loops perform very well with small number of	2303	=item * C-based event loops perform very well with small number of
1645	watchers, as the management overhead dominates.	2304	watchers, as the management overhead dominates.
1646		2305
1647	=back	2306	=back
1648		2307
		2308	=head2 THE IO::Lambda BENCHMARK
		2309
		2310	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2311	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2312	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2313	shouldn't come as a surprise to anybody). As such, the benchmark is
		2314	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2315	very optimal. But how would AnyEvent compare when used without the extra
		2316	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2317
		2318	The benchmark itself creates an echo-server, and then, for 500 times,
		2319	connects to the echo server, sends a line, waits for the reply, and then
		2320	creates the next connection. This is a rather bad benchmark, as it doesn't
		2321	test the efficiency of the framework or much non-blocking I/O, but it is a
		2322	benchmark nevertheless.
		2323
		2324	name runtime
		2325	Lambda/select 0.330 sec
		2326	+ optimized 0.122 sec
		2327	Lambda/AnyEvent 0.327 sec
		2328	+ optimized 0.138 sec
		2329	Raw sockets/select 0.077 sec
		2330	POE/select, components 0.662 sec
		2331	POE/select, raw sockets 0.226 sec
		2332	POE/select, optimized 0.404 sec
		2333
		2334	AnyEvent/select/nb 0.085 sec
		2335	AnyEvent/EV/nb 0.068 sec
		2336	+state machine 0.134 sec
		2337
		2338	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2339	benchmarks actually make blocking connects and use 100% blocking I/O,
		2340	defeating the purpose of an event-based solution. All of the newly
		2341	written AnyEvent benchmarks use 100% non-blocking connects (using
		2342	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2343	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2344	generally require a lot more bookkeeping and event handling than blocking
		2345	connects (which involve a single syscall only).
		2346
		2347	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2348	offers similar expressive power as POE and IO::Lambda, using conventional
		2349	Perl syntax. This means that both the echo server and the client are 100%
		2350	non-blocking, further placing it at a disadvantage.
		2351
		2352	As you can see, the AnyEvent + EV combination even beats the
		2353	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2354	backend easily beats IO::Lambda and POE.
		2355
		2356	And even the 100% non-blocking version written using the high-level (and
		2357	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2358	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2359	in a non-blocking way.
		2360
		2361	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2362	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2363	part of the IO::lambda distribution and were used without any changes.
		2364
		2365
		2366	=head1 SIGNALS
		2367
		2368	AnyEvent currently installs handlers for these signals:
		2369
		2370	=over 4
		2371
		2372	=item SIGCHLD
		2373
		2374	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2375	emulation for event loops that do not support them natively. Also, some
		2376	event loops install a similar handler.
		2377
		2378	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2379	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2380
		2381	=item SIGPIPE
		2382
		2383	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2384	when AnyEvent gets loaded.
		2385
		2386	The rationale for this is that AnyEvent users usually do not really depend
		2387	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2388	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2389	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2390	some random socket.
		2391
		2392	The rationale for installing a no-op handler as opposed to ignoring it is
		2393	that this way, the handler will be restored to defaults on exec.
		2394
		2395	Feel free to install your own handler, or reset it to defaults.
		2396
		2397	=back
		2398
		2399	=cut
		2400
		2401	undef $SIG{CHLD}
		2402	if $SIG{CHLD} eq 'IGNORE';
		2403
		2404	$SIG{PIPE} = sub { }
		2405	unless defined $SIG{PIPE};
		2406
		2407	=head1 RECOMMENDED/OPTIONAL MODULES
		2408
		2409	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2410	it's built-in modules) are required to use it.
		2411
		2412	That does not mean that AnyEvent won't take advantage of some additional
		2413	modules if they are installed.
		2414
		2415	This section epxlains which additional modules will be used, and how they
		2416	affect AnyEvent's operetion.
		2417
		2418	=over 4
		2419
		2420	=item L<Async::Interrupt>
		2421
		2422	This slightly arcane module is used to implement fast signal handling: To
		2423	my knowledge, there is no way to do completely race-free and quick
		2424	signal handling in pure perl. To ensure that signals still get
		2425	delivered, AnyEvent will start an interval timer to wake up perl (and
		2426	catch the signals) with some delay (default is 10 seconds, look for
		2427	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2428
		2429	If this module is available, then it will be used to implement signal
		2430	catching, which means that signals will not be delayed, and the event loop
		2431	will not be interrupted regularly, which is more efficient (And good for
		2432	battery life on laptops).
		2433
		2434	This affects not just the pure-perl event loop, but also other event loops
		2435	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2436
		2437	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2438	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2439	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2440	does nothing for those backends.
		2441
		2442	=item L<EV>
		2443
		2444	This module isn't really "optional", as it is simply one of the backend
		2445	event loops that AnyEvent can use. However, it is simply the best event
		2446	loop available in terms of features, speed and stability: It supports
		2447	the AnyEvent API optimally, implements all the watcher types in XS, does
		2448	automatic timer adjustments even when no monotonic clock is available,
		2449	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2450	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2451	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2452
		2453	=item L<Guard>
		2454
		2455	The guard module, when used, will be used to implement
		2456	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2457	lot less memory), but otherwise doesn't affect guard operation much. It is
		2458	purely used for performance.
		2459
		2460	=item L<JSON> and L<JSON::XS>
		2461
		2462	This module is required when you want to read or write JSON data via
		2463	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2464	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2465
		2466	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2467	installed.
		2468
		2469	=item L<Net::SSLeay>
		2470
		2471	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2472	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2473	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2474
		2475	=item L<Time::HiRes>
		2476
		2477	This module is part of perl since release 5.008. It will be used when the
		2478	chosen event library does not come with a timing source on it's own. The
		2479	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2480	try to use a monotonic clock for timing stability.
		2481
		2482	=back
		2483
1649		2484
1650	=head1 FORK	2485	=head1 FORK
1651		2486
1652	Most event libraries are not fork-safe. The ones who are usually are	2487	Most event libraries are not fork-safe. The ones who are usually are
1653	because they rely on inefficient but fork-safe C<select> or C<poll>	2488	because they rely on inefficient but fork-safe C<select> or C<poll>
1654	calls. Only L<EV> is fully fork-aware.	2489	calls. Only L<EV> is fully fork-aware.
1655		2490
1656	If you have to fork, you must either do so I<before> creating your first	2491	If you have to fork, you must either do so I<before> creating your first
1657	watcher OR you must not use AnyEvent at all in the child.	2492	watcher OR you must not use AnyEvent at all in the child OR you must do
		2493	something completely out of the scope of AnyEvent.
1658		2494
1659		2495
1660	=head1 SECURITY CONSIDERATIONS	2496	=head1 SECURITY CONSIDERATIONS
1661		2497
1662	AnyEvent can be forced to load any event model via	2498	AnyEvent can be forced to load any event model via
…		…
1673		2509
1674	use AnyEvent;	2510	use AnyEvent;
1675		2511
1676	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2512	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1677	be used to probe what backend is used and gain other information (which is	2513	be used to probe what backend is used and gain other information (which is
1678	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2514	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2515	$ENV{PERL_ANYEVENT_STRICT}.
		2516
		2517	Note that AnyEvent will remove I<all> environment variables starting with
		2518	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2519	enabled.
1679		2520
1680		2521
1681	=head1 BUGS	2522	=head1 BUGS
1682		2523
1683	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2524	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1684	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2525	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1685	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2526	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1686	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2527	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1687	pronounced).	2528	pronounced).
1688		2529
1689		2530
1690	=head1 SEE ALSO	2531	=head1 SEE ALSO
1691		2532
…		…
1695	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2536	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1696		2537
1697	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2538	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1698	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2539	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1699	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2540	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1700	L<AnyEvent::Impl::POE>.	2541	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1701		2542
1702	Non-blocking file handles, sockets, TCP clients and	2543	Non-blocking file handles, sockets, TCP clients and
1703	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2544	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1704		2545
1705	Asynchronous DNS: L<AnyEvent::DNS>.	2546	Asynchronous DNS: L<AnyEvent::DNS>.
1706		2547
1707	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2548	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2549	L<Coro::Event>,
1708		2550
1709	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2551	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2552	L<AnyEvent::HTTP>.
1710		2553
1711		2554
1712	=head1 AUTHOR	2555	=head1 AUTHOR
1713		2556
1714	Marc Lehmann <schmorp@schmorp.de>	2557	Marc Lehmann <schmorp@schmorp.de>

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