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Revision 1.273 by root, Thu Aug 6 13:45:04 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 $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		409	variable can be changed only before the first signal watcher is created,
		410	and should be left alone otherwise. This variable determines how often
		411	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		412	will cause fewer spurious wake-ups, which is better for power and CPU
		413	saving.
		414
		415	All these problems can be avoided by installing the optional
		416	L<Async::Interrupt> module, which works with most event loops. It will not
		417	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		418	(and not with L<POE> currently, as POE does it's own workaround with
		419	one-second latency). For those, you just have to suffer the delays.
		420
332	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
333		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
334	You can also watch on a child process exit and catch its exit status.	425	You can also watch on a child process exit and catch its exit status.
335		426
336	The child process is specified by the C<pid> argument (if set to C<0>, it	427	The child process is specified by the C<pid> argument (one some backends,
337	watches for any child process exit). The watcher will trigger as often	428	using C<0> watches for any child process exit, on others this will
338	as status change for the child are received. This works by installing a	429	croak). The watcher will be triggered only when the child process has
339	signal handler for C<SIGCHLD>. The callback will be called with the pid	430	finished and an exit status is available, not on any trace events
340	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	432
		433	The callback will be called with the pid and exit status (as returned by
		434	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		435	callback arguments.
		436
		437	This watcher type works by installing a signal handler for C<SIGCHLD>,
		438	and since it cannot be shared, nothing else should use SIGCHLD or reap
		439	random child processes (waiting for specific child processes, e.g. inside
		440	C<system>, is just fine).
342		441
343	There is a slight catch to child watchers, however: you usually start them	442	There is a slight catch to child watchers, however: you usually start them
344	I<after> the child process was created, and this means the process could	443	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
346		445
347	Not all event models handle this correctly (POE doesn't), but even for	446	Not all event models handle this correctly (neither POE nor IO::Async do,
		447	see their AnyEvent::Impl manpages for details), but even for event models
348	event models that I<do> handle this correctly, they usually need to be	448	that I<do> handle this correctly, they usually need to be loaded before
349	loaded before the process exits (i.e. before you fork in the first place).	449	the process exits (i.e. before you fork in the first place). AnyEvent's
		450	pure perl event loop handles all cases correctly regardless of when you
		451	start the watcher.
350		452
351	This means you cannot create a child watcher as the very first thing in an	453	This means you cannot create a child watcher as the very first
352	AnyEvent program, you I<have> to create at least one watcher before you	454	thing in an AnyEvent program, you I<have> to create at least one
353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	455	watcher before you C<fork> the child (alternatively, you can call
		456	C<AnyEvent::detect>).
		457
		458	As most event loops do not support waiting for child events, they will be
		459	emulated by AnyEvent in most cases, in which the latency and race problems
		460	mentioned in the description of signal watchers apply.
354		461
355	Example: fork a process and wait for it	462	Example: fork a process and wait for it
356		463
357	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
358		465
…		…
368	);	475	);
369		476
370	# do something else, then wait for process exit	477	# do something else, then wait for process exit
371	$done->recv;	478	$done->recv;
372		479
		480	=head2 IDLE WATCHERS
		481
		482	$w = AnyEvent->idle (cb => <callback>);
		483
		484	Sometimes there is a need to do something, but it is not so important
		485	to do it instantly, but only when there is nothing better to do. This
		486	"nothing better to do" is usually defined to be "no other events need
		487	attention by the event loop".
		488
		489	Idle watchers ideally get invoked when the event loop has nothing
		490	better to do, just before it would block the process to wait for new
		491	events. Instead of blocking, the idle watcher is invoked.
		492
		493	Most event loops unfortunately do not really support idle watchers (only
		494	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		495	will simply call the callback "from time to time".
		496
		497	Example: read lines from STDIN, but only process them when the
		498	program is otherwise idle:
		499
		500	my @lines; # read data
		501	my $idle_w;
		502	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		503	push @lines, scalar <STDIN>;
		504
		505	# start an idle watcher, if not already done
		506	$idle_w ||= AnyEvent->idle (cb => sub {
		507	# handle only one line, when there are lines left
		508	if (my $line = shift @lines) {
		509	print "handled when idle: $line";
		510	} else {
		511	# otherwise disable the idle watcher again
		512	undef $idle_w;
		513	}
		514	});
		515	});
		516
373	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
374		523
375	If you are familiar with some event loops you will know that all of them	524	If you are familiar with some event loops you will know that all of them
376	require you to run some blocking "loop", "run" or similar function that	525	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
378		527
379	AnyEvent is different, it expects somebody else to run the event loop and	528	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	529	loop and will only block when necessary (usually when told by the user).
381		530
382	The instrument to do that is called a "condition variable", so called	531	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	532	because they represent a condition that must become true.
		533
		534	Now is probably a good time to look at the examples further below.
384		535
385	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	538	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
389		541
390	After creation, the condition variable is "false" until it becomes "true"	542	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	543	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<<	544	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	545	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	548	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	550	another way to call them is transactions - each condition variable can be
399	used to represent a transaction, which finishes at some point and delivers	551	used to represent a transaction, which finishes at some point and delivers
400	a result.	552	a result. And yet some people know them as "futures" - a promise to
		553	compute/deliver something that you can wait for.
401		554
402	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	556	for example, if you write a module that does asynchronous http requests,
404	then a condition variable would be the ideal candidate to signal the	557	then a condition variable would be the ideal candidate to signal the
405	availability of results. The user can either act when the callback is	558	availability of results. The user can either act when the callback is
…		…
439	after => 1,	592	after => 1,
440	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
441	);	594	);
442		595
443	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
444	# calls send	597	# calls -<send
445	$result_ready->recv;	598	$result_ready->recv;
446		599
447	Example: wait for a timer, but take advantage of the fact that	600	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	601	variables are also callable directly.
449		602
450	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	605	$done->recv;
		606
		607	Example: Imagine an API that returns a condvar and doesn't support
		608	callbacks. This is how you make a synchronous call, for example from
		609	the main program:
		610
		611	use AnyEvent::CouchDB;
		612
		613	...
		614
		615	my @info = $couchdb->info->recv;
		616
		617	And this is how you would just set a callback to be called whenever the
		618	results are available:
		619
		620	$couchdb->info->cb (sub {
		621	my @info = $_[0]->recv;
		622	});
453		623
454	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
455		625
456	These methods should only be used by the producing side, i.e. the	626	These methods should only be used by the producing side, i.e. the
457	code/module that eventually sends the signal. Note that it is also	627	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	640	immediately from within send.
471		641
472	Any arguments passed to the C<send> call will be returned by all	642	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
474		644
475	Condition variables are overloaded so one can call them directly	645	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	646	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	647	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		648
484	=item $cv->croak ($error)	649	=item $cv->croak ($error)
485		650
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	651	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
488		653
489	This can be used to signal any errors to the condition variable	654	This can be used to signal any errors to the condition variable
490	user/consumer.	655	user/consumer. Doing it this way instead of calling C<croak> directly
		656	delays the error detetcion, but has the overwhelmign advantage that it
		657	diagnoses the error at the place where the result is expected, and not
		658	deep in some event clalback without connection to the actual code causing
		659	the problem.
491		660
492	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
493		662
494	=item $cv->end	663	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		664
498	These two methods can be used to combine many transactions/events into	665	These two methods can be used to combine many transactions/events into
499	one. For example, a function that pings many hosts in parallel might want	666	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
501		668
…		…
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	670	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
504	>>, the (last) callback passed to C<begin> will be executed. That callback	671	>>, 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	672	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.	673	callback was set, C<send> will be called without any arguments.
507		674
508	Let's clarify this with the ping example:	675	You can think of C<< $cv->send >> giving you an OR condition (one call
		676	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		677	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		678
		679	Let's start with a simple example: you have two I/O watchers (for example,
		680	STDOUT and STDERR for a program), and you want to wait for both streams to
		681	close before activating a condvar:
		682
		683	my $cv = AnyEvent->condvar;
		684
		685	$cv->begin; # first watcher
		686	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		687	defined sysread $fh1, my $buf, 4096
		688	or $cv->end;
		689	});
		690
		691	$cv->begin; # second watcher
		692	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		693	defined sysread $fh2, my $buf, 4096
		694	or $cv->end;
		695	});
		696
		697	$cv->recv;
		698
		699	This works because for every event source (EOF on file handle), there is
		700	one call to C<begin>, so the condvar waits for all calls to C<end> before
		701	sending.
		702
		703	The ping example mentioned above is slightly more complicated, as the
		704	there are results to be passwd back, and the number of tasks that are
		705	begung can potentially be zero:
509		706
510	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
511		708
512	my %result;	709	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
533	loop, which serves two important purposes: first, it sets the callback	730	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	731	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	732	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	733	doesn't execute once).
537		734
538	This is the general pattern when you "fan out" into multiple subrequests:	735	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>	736	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	737	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>.	738	subrequest you start, call C<begin> and for each subrequest you finish,
		739	call C<end>.
542		740
543	=back	741	=back
544		742
545	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
546		744
…		…
562	function will call C<croak>.	760	function will call C<croak>.
563		761
564	In list context, all parameters passed to C<send> will be returned,	762	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
566		764
		765	Note that doing a blocking wait in a callback is not supported by any
		766	event loop, that is, recursive invocation of a blocking C<< ->recv
		767	>> is not allowed, and the C<recv> call will C<croak> if such a
		768	condition is detected. This condition can be slightly loosened by using
		769	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		770	any thread that doesn't run the event loop itself.
		771
567	Not all event models support a blocking wait - some die in that case	772	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	773	(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	774	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	775	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	777	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
574		779
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	780	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	781	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	782	time). This will work even when the event loop does not support blocking
589	waits otherwise.	783	waits otherwise.
590		784
591	=item $bool = $cv->ready	785	=item $bool = $cv->ready
592		786
593	Returns true when the condition is "true", i.e. whether C<send> or	787	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	788	C<croak> have been called.
595		789
596	=item $cb = $cv->cb ([new callback])	790	=item $cb = $cv->cb ($cb->($cv))
597		791
598	This is a mutator function that returns the callback set and optionally	792	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	793	replaces it before doing so.
600		794
601	The callback will be called when the condition becomes "true", i.e. when	795	The callback will be called when the condition becomes (or already was)
602	C<send> or C<croak> are called, with the only argument being the condition	796	"true", i.e. when C<send> or C<croak> are called (or were called), with
603	variable itself. Calling C<recv> inside the callback or at any later time	797	the only argument being the condition variable itself. Calling C<recv>
604	is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
605		799
606	=back	800	=back
607		801
		802	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		803
		804	The available backend classes are (every class has its own manpage):
		805
		806	=over 4
		807
		808	=item Backends that are autoprobed when no other event loop can be found.
		809
		810	EV is the preferred backend when no other event loop seems to be in
		811	use. If EV is not installed, then AnyEvent will try Event, and, failing
		812	that, will fall back to its own pure-perl implementation, which is
		813	available everywhere as it comes with AnyEvent itself.
		814
		815	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		816	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		817	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		818
		819	=item Backends that are transparently being picked up when they are used.
		820
		821	These will be used when they are currently loaded when the first watcher
		822	is created, in which case it is assumed that the application is using
		823	them. This means that AnyEvent will automatically pick the right backend
		824	when the main program loads an event module before anything starts to
		825	create watchers. Nothing special needs to be done by the main program.
		826
		827	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		828	AnyEvent::Impl::Tk based on Tk, very broken.
		829	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		830	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		831	AnyEvent::Impl::Irssi used when running within irssi.
		832
		833	=item Backends with special needs.
		834
		835	Qt requires the Qt::Application to be instantiated first, but will
		836	otherwise be picked up automatically. As long as the main program
		837	instantiates the application before any AnyEvent watchers are created,
		838	everything should just work.
		839
		840	AnyEvent::Impl::Qt based on Qt.
		841
		842	Support for IO::Async can only be partial, as it is too broken and
		843	architecturally limited to even support the AnyEvent API. It also
		844	is the only event loop that needs the loop to be set explicitly, so
		845	it can only be used by a main program knowing about AnyEvent. See
		846	L<AnyEvent::Impl::Async> for the gory details.
		847
		848	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		849
		850	=item Event loops that are indirectly supported via other backends.
		851
		852	Some event loops can be supported via other modules:
		853
		854	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		855
		856	B<WxWidgets> has no support for watching file handles. However, you can
		857	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		858	polls 20 times per second, which was considered to be too horrible to even
		859	consider for AnyEvent.
		860
		861	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		862	backend, so it can be supported through POE.
		863
		864	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		865	load L<POE> when detecting them, in the hope that POE will pick them up,
		866	in which case everything will be automatic.
		867
		868	=back
		869
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
610	=over 4	875	=over 4
611		876
612	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
613		878
614	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
615	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		886	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		887
641	=item AnyEvent::detect	888	=item AnyEvent::detect
642		889
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	891	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	892	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	893	runtime, and not e.g. while initialising of your module.
		894
		895	If you need to do some initialisation before AnyEvent watchers are
		896	created, use C<post_detect>.
647		897
648	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
649		899
650	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
652		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		905	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		906	other initialisations - see the sources of L<AnyEvent::Strict> or
		907	L<AnyEvent::AIO> to see how this is used.
		908
		909	The most common usage is to create some global watchers, without forcing
		910	event module detection too early, for example, L<AnyEvent::AIO> creates
		911	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		912	avoid autodetecting the event module at load time.
		913
653	If called in scalar or list context, then it creates and returns an object	914	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	915	that automatically removes the callback again when it is destroyed (or
		916	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	917	a case where this is useful.
		918
		919	Example: Create a watcher for the IO::AIO module and store it in
		920	C<$WATCHER>. Only do so after the event loop is initialised, though.
		921
		922	our WATCHER;
		923
		924	my $guard = AnyEvent::post_detect {
		925	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		926	};
		927
		928	# the ||= is important in case post_detect immediately runs the block,
		929	# as to not clobber the newly-created watcher. assigning both watcher and
		930	# post_detect guard to the same variable has the advantage of users being
		931	# able to just C<undef $WATCHER> if the watcher causes them grief.
		932
		933	$WATCHER ||= $guard;
656		934
657	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
658		936
659	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	939	the event loop has been chosen.
662		940
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	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,	942	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	943	array will be ignored.
666		944
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	945	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		946	it,as it takes care of these details.
		947
		948	This variable is mainly useful for modules that can do something useful
		949	when AnyEvent is used and thus want to know when it is initialised, but do
		950	not need to even load it by default. This array provides the means to hook
		951	into AnyEvent passively, without loading it.
668		952
669	=back	953	=back
670		954
671	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
672		956
…		…
727		1011
728		1012
729	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
730		1014
731	The following is a non-exhaustive list of additional modules that use	1015	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1016	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	1017	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
735		1019
736	=over 4	1020	=over 4
737		1021
738	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
739		1023
740	Contains various utility functions that replace often-used but blocking	1024	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1025	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		1026
747	=item L<AnyEvent::Socket>	1027	=item L<AnyEvent::Socket>
748		1028
749	Provides various utility functions for (internet protocol) sockets,	1029	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1030	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1031	connections or tcp servers, with IPv6 and SRV record support and more.
752		1032
		1033	=item L<AnyEvent::Handle>
		1034
		1035	Provide read and write buffers, manages watchers for reads and writes,
		1036	supports raw and formatted I/O, I/O queued and fully transparent and
		1037	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1038
753	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
754		1040
755	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
756		1042
		1043	=item L<AnyEvent::HTTP>
		1044
		1045	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1046	HTTP requests.
		1047
757	=item L<AnyEvent::HTTPD>	1048	=item L<AnyEvent::HTTPD>
758		1049
759	Provides a simple web application server framework.	1050	Provides a simple web application server framework.
760		1051
761	=item L<AnyEvent::FastPing>	1052	=item L<AnyEvent::FastPing>
762		1053
763	The fastest ping in the west.	1054	The fastest ping in the west.
764		1055
		1056	=item L<AnyEvent::DBI>
		1057
		1058	Executes L<DBI> requests asynchronously in a proxy process.
		1059
		1060	=item L<AnyEvent::AIO>
		1061
		1062	Truly asynchronous I/O, should be in the toolbox of every event
		1063	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1064	together.
		1065
		1066	=item L<AnyEvent::BDB>
		1067
		1068	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1069	L<BDB> and AnyEvent together.
		1070
		1071	=item L<AnyEvent::GPSD>
		1072
		1073	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1074
765	=item L<Net::IRC3>	1075	=item L<AnyEvent::IRC>
766		1076
767	AnyEvent based IRC client module family.	1077	AnyEvent based IRC client module family (replacing the older Net::IRC3).
768		1078
769	=item L<Net::XMPP2>	1079	=item L<AnyEvent::XMPP>
770		1080
771	AnyEvent based XMPP (Jabber protocol) module family.	1081	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1082	Net::XMPP2>.
		1083
		1084	=item L<AnyEvent::IGS>
		1085
		1086	A non-blocking interface to the Internet Go Server protocol (used by
		1087	L<App::IGS>).
772		1088
773	=item L<Net::FCP>	1089	=item L<Net::FCP>
774		1090
775	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
776	of AnyEvent.	1092	of AnyEvent.
…		…
781		1097
782	=item L<Coro>	1098	=item L<Coro>
783		1099
784	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
785		1101
786	=item L<AnyEvent::AIO>, L<IO::AIO>
787
788	Truly asynchronous I/O, should be in the toolbox of every event
789	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
790	together.
791
792	=item L<AnyEvent::BDB>, L<BDB>
793
794	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
795	IO::AIO and AnyEvent together.
796
797	=item L<IO::Lambda>
798
799	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
800
801	=back	1102	=back
802		1103
803	=cut	1104	=cut
804		1105
805	package AnyEvent;	1106	package AnyEvent;
806		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
807	no warnings;	1110	# no warnings
808	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
809		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
810	use Carp;	1118	use Carp ();
811		1119
812	our $VERSION = 4.14;	1120	our $VERSION = 4.91;
813	our $MODEL;	1121	our $MODEL;
814		1122
815	our $AUTOLOAD;	1123	our $AUTOLOAD;
816	our @ISA;	1124	our @ISA;
817		1125
818	our @REGISTRY;	1126	our @REGISTRY;
819		1127
820	our $WIN32;	1128	our $WIN32;
821		1129
		1130	our $VERBOSE;
		1131
822	BEGIN {	1132	BEGIN {
823	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
824	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
825	}
826		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
828		1144
829	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
830		1146
831	{	1147	{
832	my $idx;	1148	my $idx;
…		…
834	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
835	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
836	}	1152	}
837		1153
838	my @models = (	1154	my @models = (
839	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
840	[Event:: => AnyEvent::Impl::Event::],	1156	[Event:: => AnyEvent::Impl::Event::, 1],
841	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1157	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
842	# everything below here will not be autoprobed	1158	# everything below here will not (normally) be autoprobed
843	# as the pureperl backend should work everywhere	1159	# as the pureperl backend should work everywhere
844	# and is usually faster	1160	# and is usually faster
		1161	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1162	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1163	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
845	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
846	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
850	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
851	[Prima:: => AnyEvent::Impl::POE::],	1168	[Prima:: => AnyEvent::Impl::POE::],
		1169	# IO::Async is just too broken - we would need workarounds for its
		1170	# byzantine signal and broken child handling, among others.
		1171	# IO::Async is rather hard to detect, as it doesn't have any
		1172	# obvious default class.
		1173	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
852	);	1176	);
853		1177
854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1178	our %method = map +($_ => 1),
		1179	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
855		1180
856	our @post_detect;	1181	our @post_detect;
857		1182
858	sub post_detect(&) {	1183	sub post_detect(&) {
859	my ($cb) = @_;	1184	my ($cb) = @_;
860		1185
861	if ($MODEL) {	1186	if ($MODEL) {
862	$cb->();	1187	$cb->();
863		1188
864	1	1189	undef
865	} else {	1190	} else {
866	push @post_detect, $cb;	1191	push @post_detect, $cb;
867		1192
868	defined wantarray	1193	defined wantarray
869	? bless \$cb, "AnyEvent::Util::PostDetect"	1194	? bless \$cb, "AnyEvent::Util::postdetect"
870	: ()	1195	: ()
871	}	1196	}
872	}	1197	}
873		1198
874	sub AnyEvent::Util::PostDetect::DESTROY {	1199	sub AnyEvent::Util::postdetect::DESTROY {
875	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1200	@post_detect = grep $_ != ${$_[0]}, @post_detect;
876	}	1201	}
877		1202
878	sub detect() {	1203	sub detect() {
879	unless ($MODEL) {	1204	unless ($MODEL) {
880	no strict 'refs';
881	local $SIG{__DIE__};	1205	local $SIG{__DIE__};
882		1206
883	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1207	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
884	my $model = "AnyEvent::Impl::$1";	1208	my $model = "AnyEvent::Impl::$1";
885	if (eval "require $model") {	1209	if (eval "require $model") {
886	$MODEL = $model;	1210	$MODEL = $model;
887	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1211	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
888	} else {	1212	} else {
889	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1213	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
890	}	1214	}
891	}	1215	}
892		1216
893	# check for already loaded models	1217	# check for already loaded models
894	unless ($MODEL) {	1218	unless ($MODEL) {
895	for (@REGISTRY, @models) {	1219	for (@REGISTRY, @models) {
896	my ($package, $model) = @$_;	1220	my ($package, $model) = @$_;
897	if (${"$package\::VERSION"} > 0) {	1221	if (${"$package\::VERSION"} > 0) {
898	if (eval "require $model") {	1222	if (eval "require $model") {
899	$MODEL = $model;	1223	$MODEL = $model;
900	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1224	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
901	last;	1225	last;
902	}	1226	}
903	}	1227	}
904	}	1228	}
905		1229
906	unless ($MODEL) {	1230	unless ($MODEL) {
907	# try to load a model	1231	# try to autoload a model
908
909	for (@REGISTRY, @models) {	1232	for (@REGISTRY, @models) {
910	my ($package, $model) = @$_;	1233	my ($package, $model, $autoload) = @$_;
		1234	if (
		1235	$autoload
911	if (eval "require $package"	1236	and eval "require $package"
912	and ${"$package\::VERSION"} > 0	1237	and ${"$package\::VERSION"} > 0
913	and eval "require $model") {	1238	and eval "require $model"
		1239	) {
914	$MODEL = $model;	1240	$MODEL = $model;
915	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1241	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
916	last;	1242	last;
917	}	1243	}
918	}	1244	}
919		1245
920	$MODEL	1246	$MODEL
921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1247	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
922	}	1248	}
923	}	1249	}
924		1250
		1251	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1252
925	unshift @ISA, $MODEL;	1253	unshift @ISA, $MODEL;
926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1254
		1255	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927		1256
928	(shift @post_detect)->() while @post_detect;	1257	(shift @post_detect)->() while @post_detect;
929	}	1258	}
930		1259
931	$MODEL	1260	$MODEL
…		…
933		1262
934	sub AUTOLOAD {	1263	sub AUTOLOAD {
935	(my $func = $AUTOLOAD) =~ s/.*://;	1264	(my $func = $AUTOLOAD) =~ s/.*://;
936		1265
937	$method{$func}	1266	$method{$func}
938	or croak "$func: not a valid method for AnyEvent objects";	1267	or Carp::croak "$func: not a valid method for AnyEvent objects";
939		1268
940	detect unless $MODEL;	1269	detect unless $MODEL;
941		1270
942	my $class = shift;	1271	my $class = shift;
943	$class->$func (@_);	1272	$class->$func (@_);
944	}	1273	}
945		1274
		1275	# utility function to dup a filehandle. this is used by many backends
		1276	# to support binding more than one watcher per filehandle (they usually
		1277	# allow only one watcher per fd, so we dup it to get a different one).
		1278	sub _dupfh($$;$$) {
		1279	my ($poll, $fh, $r, $w) = @_;
		1280
		1281	# cygwin requires the fh mode to be matching, unix doesn't
		1282	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1283
		1284	open my $fh2, $mode, $fh
		1285	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1286
		1287	# we assume CLOEXEC is already set by perl in all important cases
		1288
		1289	($fh2, $rw)
		1290	}
		1291
		1292	#############################################################################
		1293	# "new" API, currently only emulation of it
		1294	#############################################################################
		1295
		1296	package AE;
		1297
		1298	sub io($$$) {
		1299	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1300	}
		1301
		1302	sub timer($$$) {
		1303	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1304	}
		1305
		1306	sub signal($$) {
		1307	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1308	}
		1309
		1310	sub child($$) {
		1311	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1312	}
		1313
		1314	sub idle($) {
		1315	AnyEvent->idle (cb => $_[0]);
		1316	}
		1317
		1318	sub cv(;&) {
		1319	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1320	}
		1321
		1322	sub now() {
		1323	AnyEvent->now
		1324	}
		1325
		1326	sub now_update() {
		1327	AnyEvent->now_update
		1328	}
		1329
		1330	sub time() {
		1331	AnyEvent->time
		1332	}
		1333
946	package AnyEvent::Base;	1334	package AnyEvent::Base;
947		1335
948	# default implementation for now and time	1336	# default implementations for many methods
949		1337
950	use Time::HiRes ();	1338	sub _time {
		1339	# probe for availability of Time::HiRes
		1340	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1341	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1342	*_time = \&Time::HiRes::time;
		1343	# if (eval "use POSIX (); (POSIX::times())...
		1344	} else {
		1345	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1346	*_time = sub { time }; # epic fail
		1347	}
951		1348
952	sub time { Time::HiRes::time }	1349	&_time
953	sub now { Time::HiRes::time }	1350	}
		1351
		1352	sub time { _time }
		1353	sub now { _time }
		1354	sub now_update { }
954		1355
955	# default implementation for ->condvar	1356	# default implementation for ->condvar
956		1357
957	sub condvar {	1358	sub condvar {
958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1359	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
959	}	1360	}
960		1361
961	# default implementation for ->signal	1362	# default implementation for ->signal
962		1363
963	our %SIG_CB;	1364	our $HAVE_ASYNC_INTERRUPT;
		1365
		1366	sub _have_async_interrupt() {
		1367	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1368	&& eval "use Async::Interrupt 1.0 (); 1")
		1369	unless defined $HAVE_ASYNC_INTERRUPT;
		1370
		1371	$HAVE_ASYNC_INTERRUPT
		1372	}
		1373
		1374	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1375	our (%SIG_ASY, %SIG_ASY_W);
		1376	our ($SIG_COUNT, $SIG_TW);
		1377
		1378	sub _signal_exec {
		1379	$HAVE_ASYNC_INTERRUPT
		1380	? $SIGPIPE_R->drain
		1381	: sysread $SIGPIPE_R, my $dummy, 9;
		1382
		1383	while (%SIG_EV) {
		1384	for (keys %SIG_EV) {
		1385	delete $SIG_EV{$_};
		1386	$_->() for values %{ $SIG_CB{$_} || {} };
		1387	}
		1388	}
		1389	}
		1390
		1391	# install a dummy wakeup watcher to reduce signal catching latency
		1392	sub _sig_add() {
		1393	unless ($SIG_COUNT++) {
		1394	# try to align timer on a full-second boundary, if possible
		1395	my $NOW = AE::now;
		1396
		1397	$SIG_TW = AE::timer
		1398	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1399	$MAX_SIGNAL_LATENCY,
		1400	sub { } # just for the PERL_ASYNC_CHECK
		1401	;
		1402	}
		1403	}
		1404
		1405	sub _sig_del {
		1406	undef $SIG_TW
		1407	unless --$SIG_COUNT;
		1408	}
		1409
		1410	our $_sig_name_init; $_sig_name_init = sub {
		1411	eval q{ # poor man's autoloading
		1412	undef $_sig_name_init;
		1413
		1414	if (_have_async_interrupt) {
		1415	*sig2num = \&Async::Interrupt::sig2num;
		1416	*sig2name = \&Async::Interrupt::sig2name;
		1417	} else {
		1418	require Config;
		1419
		1420	my %signame2num;
		1421	@signame2num{ split ' ', $Config::Config{sig_name} }
		1422	= split ' ', $Config::Config{sig_num};
		1423
		1424	my @signum2name;
		1425	@signum2name[values %signame2num] = keys %signame2num;
		1426
		1427	*sig2num = sub($) {
		1428	$_[0] > 0 ? shift : $signame2num{+shift}
		1429	};
		1430	*sig2name = sub ($) {
		1431	$_[0] > 0 ? $signum2name[+shift] : shift
		1432	};
		1433	}
		1434	};
		1435	die if $@;
		1436	};
		1437
		1438	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1439	sub sig2name($) { &$_sig_name_init; &sig2name }
964		1440
965	sub signal {	1441	sub signal {
		1442	eval q{ # poor man's autoloading {}
		1443	# probe for availability of Async::Interrupt
		1444	if (_have_async_interrupt) {
		1445	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1446
		1447	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1448	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1449
		1450	} else {
		1451	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1452
		1453	require Fcntl;
		1454
		1455	if (AnyEvent::WIN32) {
		1456	require AnyEvent::Util;
		1457
		1458	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1459	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1460	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1461	} else {
		1462	pipe $SIGPIPE_R, $SIGPIPE_W;
		1463	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1464	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1465
		1466	# not strictly required, as $^F is normally 2, but let's make sure...
		1467	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1468	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1469	}
		1470
		1471	$SIGPIPE_R
		1472	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1473
		1474	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1475	}
		1476
		1477	*signal = sub {
966	my (undef, %arg) = @_;	1478	my (undef, %arg) = @_;
967		1479
968	my $signal = uc $arg{signal}	1480	my $signal = uc $arg{signal}
969	or Carp::croak "required option 'signal' is missing";	1481	or Carp::croak "required option 'signal' is missing";
970		1482
		1483	if ($HAVE_ASYNC_INTERRUPT) {
		1484	# async::interrupt
		1485
		1486	$signal = sig2num $signal;
971	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1487	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1488
		1489	$SIG_ASY{$signal} ||= new Async::Interrupt
		1490	cb => sub { undef $SIG_EV{$signal} },
		1491	signal => $signal,
		1492	pipe => [$SIGPIPE_R->filenos],
		1493	pipe_autodrain => 0,
		1494	;
		1495
		1496	} else {
		1497	# pure perl
		1498
		1499	# AE::Util has been loaded in signal
		1500	$signal = sig2name $signal;
		1501	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1502
972	$SIG{$signal} ||= sub {	1503	$SIG{$signal} ||= sub {
973	$_->() for values %{ $SIG_CB{$signal} || {} };	1504	local $!;
		1505	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1506	undef $SIG_EV{$signal};
		1507	};
		1508
		1509	# can't do signal processing without introducing races in pure perl,
		1510	# so limit the signal latency.
		1511	_sig_add;
		1512	}
		1513
		1514	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1515	};
		1516
		1517	*AnyEvent::Base::signal::DESTROY = sub {
		1518	my ($signal, $cb) = @{$_[0]};
		1519
		1520	_sig_del;
		1521
		1522	delete $SIG_CB{$signal}{$cb};
		1523
		1524	$HAVE_ASYNC_INTERRUPT
		1525	? delete $SIG_ASY{$signal}
		1526	: # delete doesn't work with older perls - they then
		1527	# print weird messages, or just unconditionally exit
		1528	# instead of getting the default action.
		1529	undef $SIG{$signal}
		1530	unless keys %{ $SIG_CB{$signal} };
		1531	};
974	};	1532	};
975		1533	die if $@;
976	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1534	&signal
977	}
978
979	sub AnyEvent::Base::Signal::DESTROY {
980	my ($signal, $cb) = @{$_[0]};
981
982	delete $SIG_CB{$signal}{$cb};
983
984	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
985	}	1535	}
986		1536
987	# default implementation for ->child	1537	# default implementation for ->child
988		1538
989	our %PID_CB;	1539	our %PID_CB;
990	our $CHLD_W;	1540	our $CHLD_W;
991	our $CHLD_DELAY_W;	1541	our $CHLD_DELAY_W;
992	our $PID_IDLE;
993	our $WNOHANG;	1542	our $WNOHANG;
994		1543
995	sub _child_wait {	1544	sub _emit_childstatus($$) {
996	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1545	my (undef, $rpid, $rstatus) = @_;
		1546
		1547	$_->($rpid, $rstatus)
997	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1548	for values %{ $PID_CB{$rpid} || {} },
998	(values %{ $PID_CB{0} || {} });	1549	values %{ $PID_CB{0} || {} };
999	}
1000
1001	undef $PID_IDLE;
1002	}	1550	}
1003		1551
1004	sub _sigchld {	1552	sub _sigchld {
1005	# make sure we deliver these changes "synchronous" with the event loop.	1553	my $pid;
1006	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1554
1007	undef $CHLD_DELAY_W;	1555	AnyEvent->_emit_childstatus ($pid, $?)
1008	&_child_wait;	1556	while ($pid = waitpid -1, $WNOHANG) > 0;
1009	});
1010	}	1557	}
1011		1558
1012	sub child {	1559	sub child {
1013	my (undef, %arg) = @_;	1560	my (undef, %arg) = @_;
1014		1561
1015	defined (my $pid = $arg{pid} + 0)	1562	defined (my $pid = $arg{pid} + 0)
1016	or Carp::croak "required option 'pid' is missing";	1563	or Carp::croak "required option 'pid' is missing";
1017		1564
1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1565	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1019		1566
1020	unless ($WNOHANG) {	1567	# WNOHANG is almost cetrainly 1 everywhere
		1568	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1569	? 1
1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1570	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1022	}
1023		1571
1024	unless ($CHLD_W) {	1572	unless ($CHLD_W) {
1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1573	$CHLD_W = AE::signal CHLD => \&_sigchld;
1026	# child could be a zombie already, so make at least one round	1574	# child could be a zombie already, so make at least one round
1027	&_sigchld;	1575	&_sigchld;
1028	}	1576	}
1029		1577
1030	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1578	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1031	}	1579	}
1032		1580
1033	sub AnyEvent::Base::Child::DESTROY {	1581	sub AnyEvent::Base::child::DESTROY {
1034	my ($pid, $cb) = @{$_[0]};	1582	my ($pid, $cb) = @{$_[0]};
1035		1583
1036	delete $PID_CB{$pid}{$cb};	1584	delete $PID_CB{$pid}{$cb};
1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1585	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1038		1586
1039	undef $CHLD_W unless keys %PID_CB;	1587	undef $CHLD_W unless keys %PID_CB;
1040	}	1588	}
1041		1589
		1590	# idle emulation is done by simply using a timer, regardless
		1591	# of whether the process is idle or not, and not letting
		1592	# the callback use more than 50% of the time.
		1593	sub idle {
		1594	my (undef, %arg) = @_;
		1595
		1596	my ($cb, $w, $rcb) = $arg{cb};
		1597
		1598	$rcb = sub {
		1599	if ($cb) {
		1600	$w = _time;
		1601	&$cb;
		1602	$w = _time - $w;
		1603
		1604	# never use more then 50% of the time for the idle watcher,
		1605	# within some limits
		1606	$w = 0.0001 if $w < 0.0001;
		1607	$w = 5 if $w > 5;
		1608
		1609	$w = AE::timer $w, 0, $rcb;
		1610	} else {
		1611	# clean up...
		1612	undef $w;
		1613	undef $rcb;
		1614	}
		1615	};
		1616
		1617	$w = AE::timer 0.05, 0, $rcb;
		1618
		1619	bless \\$cb, "AnyEvent::Base::idle"
		1620	}
		1621
		1622	sub AnyEvent::Base::idle::DESTROY {
		1623	undef $${$_[0]};
		1624	}
		1625
1042	package AnyEvent::CondVar;	1626	package AnyEvent::CondVar;
1043		1627
1044	our @ISA = AnyEvent::CondVar::Base::;	1628	our @ISA = AnyEvent::CondVar::Base::;
1045		1629
1046	package AnyEvent::CondVar::Base;	1630	package AnyEvent::CondVar::Base;
1047		1631
1048	use overload	1632	#use overload
1049	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1633	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1050	fallback => 1;	1634	# fallback => 1;
		1635
		1636	# save 300+ kilobytes by dirtily hardcoding overloading
		1637	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1638	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1639	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1640	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1641
		1642	our $WAITING;
1051		1643
1052	sub _send {	1644	sub _send {
1053	# nop	1645	# nop
1054	}	1646	}
1055		1647
…		…
1068	sub ready {	1660	sub ready {
1069	$_[0]{_ae_sent}	1661	$_[0]{_ae_sent}
1070	}	1662	}
1071		1663
1072	sub _wait {	1664	sub _wait {
		1665	$WAITING
		1666	and !$_[0]{_ae_sent}
		1667	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1668
		1669	local $WAITING = 1;
1073	AnyEvent->one_event while !$_[0]{_ae_sent};	1670	AnyEvent->one_event while !$_[0]{_ae_sent};
1074	}	1671	}
1075		1672
1076	sub recv {	1673	sub recv {
1077	$_[0]->_wait;	1674	$_[0]->_wait;
…		…
1079	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1676	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1080	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1677	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1081	}	1678	}
1082		1679
1083	sub cb {	1680	sub cb {
1084	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1681	my $cv = shift;
		1682
		1683	@_
		1684	and $cv->{_ae_cb} = shift
		1685	and $cv->{_ae_sent}
		1686	and (delete $cv->{_ae_cb})->($cv);
		1687
1085	$_[0]{_ae_cb}	1688	$cv->{_ae_cb}
1086	}	1689	}
1087		1690
1088	sub begin {	1691	sub begin {
1089	++$_[0]{_ae_counter};	1692	++$_[0]{_ae_counter};
1090	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1693	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1096	}	1699	}
1097		1700
1098	# undocumented/compatibility with pre-3.4	1701	# undocumented/compatibility with pre-3.4
1099	*broadcast = \&send;	1702	*broadcast = \&send;
1100	*wait = \&_wait;	1703	*wait = \&_wait;
		1704
		1705	=head1 ERROR AND EXCEPTION HANDLING
		1706
		1707	In general, AnyEvent does not do any error handling - it relies on the
		1708	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1709	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1710	checking of all AnyEvent methods, however, which is highly useful during
		1711	development.
		1712
		1713	As for exception handling (i.e. runtime errors and exceptions thrown while
		1714	executing a callback), this is not only highly event-loop specific, but
		1715	also not in any way wrapped by this module, as this is the job of the main
		1716	program.
		1717
		1718	The pure perl event loop simply re-throws the exception (usually
		1719	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1720	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1721	so on.
		1722
		1723	=head1 ENVIRONMENT VARIABLES
		1724
		1725	The following environment variables are used by this module or its
		1726	submodules.
		1727
		1728	Note that AnyEvent will remove I<all> environment variables starting with
		1729	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1730	enabled.
		1731
		1732	=over 4
		1733
		1734	=item C<PERL_ANYEVENT_VERBOSE>
		1735
		1736	By default, AnyEvent will be completely silent except in fatal
		1737	conditions. You can set this environment variable to make AnyEvent more
		1738	talkative.
		1739
		1740	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1741	conditions, such as not being able to load the event model specified by
		1742	C<PERL_ANYEVENT_MODEL>.
		1743
		1744	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1745	model it chooses.
		1746
		1747	When set to C<8> or higher, then AnyEvent will report extra information on
		1748	which optional modules it loads and how it implements certain features.
		1749
		1750	=item C<PERL_ANYEVENT_STRICT>
		1751
		1752	AnyEvent does not do much argument checking by default, as thorough
		1753	argument checking is very costly. Setting this variable to a true value
		1754	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1755	check the arguments passed to most method calls. If it finds any problems,
		1756	it will croak.
		1757
		1758	In other words, enables "strict" mode.
		1759
		1760	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1761	>>, it is definitely recommended to keep it off in production. Keeping
		1762	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1763	can be very useful, however.
		1764
		1765	=item C<PERL_ANYEVENT_MODEL>
		1766
		1767	This can be used to specify the event model to be used by AnyEvent, before
		1768	auto detection and -probing kicks in. It must be a string consisting
		1769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1770	and the resulting module name is loaded and if the load was successful,
		1771	used as event model. If it fails to load AnyEvent will proceed with
		1772	auto detection and -probing.
		1773
		1774	This functionality might change in future versions.
		1775
		1776	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1777	could start your program like this:
		1778
		1779	PERL_ANYEVENT_MODEL=Perl perl ...
		1780
		1781	=item C<PERL_ANYEVENT_PROTOCOLS>
		1782
		1783	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1784	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1785	of auto probing).
		1786
		1787	Must be set to a comma-separated list of protocols or address families,
		1788	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1789	used, and preference will be given to protocols mentioned earlier in the
		1790	list.
		1791
		1792	This variable can effectively be used for denial-of-service attacks
		1793	against local programs (e.g. when setuid), although the impact is likely
		1794	small, as the program has to handle conenction and other failures anyways.
		1795
		1796	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1797	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1798	- only support IPv4, never try to resolve or contact IPv6
		1799	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1800	IPv6, but prefer IPv6 over IPv4.
		1801
		1802	=item C<PERL_ANYEVENT_EDNS0>
		1803
		1804	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1805	for DNS. This extension is generally useful to reduce DNS traffic, but
		1806	some (broken) firewalls drop such DNS packets, which is why it is off by
		1807	default.
		1808
		1809	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1810	EDNS0 in its DNS requests.
		1811
		1812	=item C<PERL_ANYEVENT_MAX_FORKS>
		1813
		1814	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1815	will create in parallel.
		1816
		1817	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1818
		1819	The default value for the C<max_outstanding> parameter for the default DNS
		1820	resolver - this is the maximum number of parallel DNS requests that are
		1821	sent to the DNS server.
		1822
		1823	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1824
		1825	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1826	configuration) in the default resolver. When set to the empty string, no
		1827	default config will be used.
		1828
		1829	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1830
		1831	When neither C<ca_file> nor C<ca_path> was specified during
		1832	L<AnyEvent::TLS> context creation, and either of these environment
		1833	variables exist, they will be used to specify CA certificate locations
		1834	instead of a system-dependent default.
		1835
		1836	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1837
		1838	When these are set to C<1>, then the respective modules are not
		1839	loaded. Mostly good for testing AnyEvent itself.
		1840
		1841	=back
1101		1842
1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1843	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1103		1844
1104	This is an advanced topic that you do not normally need to use AnyEvent in	1845	This is an advanced topic that you do not normally need to use AnyEvent in
1105	a module. This section is only of use to event loop authors who want to	1846	a module. This section is only of use to event loop authors who want to
…		…
1139		1880
1140	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1881	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1141	condition variables: code blocking while waiting for a condition will	1882	condition variables: code blocking while waiting for a condition will
1142	C<die>. This still works with most modules/usages, and blocking calls must	1883	C<die>. This still works with most modules/usages, and blocking calls must
1143	not be done in an interactive application, so it makes sense.	1884	not be done in an interactive application, so it makes sense.
1144
1145	=head1 ENVIRONMENT VARIABLES
1146
1147	The following environment variables are used by this module:
1148
1149	=over 4
1150
1151	=item C<PERL_ANYEVENT_VERBOSE>
1152
1153	By default, AnyEvent will be completely silent except in fatal
1154	conditions. You can set this environment variable to make AnyEvent more
1155	talkative.
1156
1157	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1158	conditions, such as not being able to load the event model specified by
1159	C<PERL_ANYEVENT_MODEL>.
1160
1161	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1162	model it chooses.
1163
1164	=item C<PERL_ANYEVENT_MODEL>
1165
1166	This can be used to specify the event model to be used by AnyEvent, before
1167	auto detection and -probing kicks in. It must be a string consisting
1168	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1169	and the resulting module name is loaded and if the load was successful,
1170	used as event model. If it fails to load AnyEvent will proceed with
1171	auto detection and -probing.
1172
1173	This functionality might change in future versions.
1174
1175	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1176	could start your program like this:
1177
1178	PERL_ANYEVENT_MODEL=Perl perl ...
1179
1180	=item C<PERL_ANYEVENT_PROTOCOLS>
1181
1182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1184	of auto probing).
1185
1186	Must be set to a comma-separated list of protocols or address families,
1187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1188	used, and preference will be given to protocols mentioned earlier in the
1189	list.
1190
1191	This variable can effectively be used for denial-of-service attacks
1192	against local programs (e.g. when setuid), although the impact is likely
1193	small, as the program has to handle connection errors already-
1194
1195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1197	- only support IPv4, never try to resolve or contact IPv6
1198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1199	IPv6, but prefer IPv6 over IPv4.
1200
1201	=item C<PERL_ANYEVENT_EDNS0>
1202
1203	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1204	for DNS. This extension is generally useful to reduce DNS traffic, but
1205	some (broken) firewalls drop such DNS packets, which is why it is off by
1206	default.
1207
1208	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1209	EDNS0 in its DNS requests.
1210
1211	=item C<PERL_ANYEVENT_MAX_FORKS>
1212
1213	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1214	will create in parallel.
1215
1216	=back
1217		1885
1218	=head1 EXAMPLE PROGRAM	1886	=head1 EXAMPLE PROGRAM
1219		1887
1220	The following program uses an I/O watcher to read data from STDIN, a timer	1888	The following program uses an I/O watcher to read data from STDIN, a timer
1221	to display a message once per second, and a condition variable to quit the	1889	to display a message once per second, and a condition variable to quit the
…		…
1415	watcher.	2083	watcher.
1416		2084
1417	=head3 Results	2085	=head3 Results
1418		2086
1419	name watchers bytes create invoke destroy comment	2087	name watchers bytes create invoke destroy comment
1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2088	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2089	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2090	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2091	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2092	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2093	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2094	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2095	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2096	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2097	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2098	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2099	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1430		2100
1431	=head3 Discussion	2101	=head3 Discussion
1432		2102
1433	The benchmark does I<not> measure scalability of the event loop very	2103	The benchmark does I<not> measure scalability of the event loop very
1434	well. For example, a select-based event loop (such as the pure perl one)	2104	well. For example, a select-based event loop (such as the pure perl one)
…		…
1459	performance becomes really bad with lots of file descriptors (and few of	2129	performance becomes really bad with lots of file descriptors (and few of
1460	them active), of course, but this was not subject of this benchmark.	2130	them active), of course, but this was not subject of this benchmark.
1461		2131
1462	The C<Event> module has a relatively high setup and callback invocation	2132	The C<Event> module has a relatively high setup and callback invocation
1463	cost, but overall scores in on the third place.	2133	cost, but overall scores in on the third place.
		2134
		2135	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2136	when using its pure perl backend.
1464		2137
1465	C<Glib>'s memory usage is quite a bit higher, but it features a	2138	C<Glib>'s memory usage is quite a bit higher, but it features a
1466	faster callback invocation and overall ends up in the same class as	2139	faster callback invocation and overall ends up in the same class as
1467	C<Event>. However, Glib scales extremely badly, doubling the number of	2140	C<Event>. However, Glib scales extremely badly, doubling the number of
1468	watchers increases the processing time by more than a factor of four,	2141	watchers increases the processing time by more than a factor of four,
…		…
1546	it to another server. This includes deleting the old timeout and creating	2219	it to another server. This includes deleting the old timeout and creating
1547	a new one that moves the timeout into the future.	2220	a new one that moves the timeout into the future.
1548		2221
1549	=head3 Results	2222	=head3 Results
1550		2223
1551	name sockets create request	2224	name sockets create request
1552	EV 20000 69.01 11.16	2225	EV 20000 69.01 11.16
1553	Perl 20000 73.32 35.87	2226	Perl 20000 73.32 35.87
		2227	IOAsync 20000 157.00 98.14 epoll
		2228	IOAsync 20000 159.31 616.06 poll
1554	Event 20000 212.62 257.32	2229	Event 20000 212.62 257.32
1555	Glib 20000 651.16 1896.30	2230	Glib 20000 651.16 1896.30
1556	POE 20000 349.67 12317.24 uses POE::Loop::Event	2231	POE 20000 349.67 12317.24 uses POE::Loop::Event
1557		2232
1558	=head3 Discussion	2233	=head3 Discussion
1559		2234
1560	This benchmark I<does> measure scalability and overall performance of the	2235	This benchmark I<does> measure scalability and overall performance of the
1561	particular event loop.	2236	particular event loop.
…		…
1563	EV is again fastest. Since it is using epoll on my system, the setup time	2238	EV is again fastest. Since it is using epoll on my system, the setup time
1564	is relatively high, though.	2239	is relatively high, though.
1565		2240
1566	Perl surprisingly comes second. It is much faster than the C-based event	2241	Perl surprisingly comes second. It is much faster than the C-based event
1567	loops Event and Glib.	2242	loops Event and Glib.
		2243
		2244	IO::Async performs very well when using its epoll backend, and still quite
		2245	good compared to Glib when using its pure perl backend.
1568		2246
1569	Event suffers from high setup time as well (look at its code and you will	2247	Event suffers from high setup time as well (look at its code and you will
1570	understand why). Callback invocation also has a high overhead compared to	2248	understand why). Callback invocation also has a high overhead compared to
1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2249	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1572	uses select or poll in basically all documented configurations.	2250	uses select or poll in basically all documented configurations.
…		…
1635	=item * C-based event loops perform very well with small number of	2313	=item * C-based event loops perform very well with small number of
1636	watchers, as the management overhead dominates.	2314	watchers, as the management overhead dominates.
1637		2315
1638	=back	2316	=back
1639		2317
		2318	=head2 THE IO::Lambda BENCHMARK
		2319
		2320	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2321	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2322	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2323	shouldn't come as a surprise to anybody). As such, the benchmark is
		2324	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2325	very optimal. But how would AnyEvent compare when used without the extra
		2326	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2327
		2328	The benchmark itself creates an echo-server, and then, for 500 times,
		2329	connects to the echo server, sends a line, waits for the reply, and then
		2330	creates the next connection. This is a rather bad benchmark, as it doesn't
		2331	test the efficiency of the framework or much non-blocking I/O, but it is a
		2332	benchmark nevertheless.
		2333
		2334	name runtime
		2335	Lambda/select 0.330 sec
		2336	+ optimized 0.122 sec
		2337	Lambda/AnyEvent 0.327 sec
		2338	+ optimized 0.138 sec
		2339	Raw sockets/select 0.077 sec
		2340	POE/select, components 0.662 sec
		2341	POE/select, raw sockets 0.226 sec
		2342	POE/select, optimized 0.404 sec
		2343
		2344	AnyEvent/select/nb 0.085 sec
		2345	AnyEvent/EV/nb 0.068 sec
		2346	+state machine 0.134 sec
		2347
		2348	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2349	benchmarks actually make blocking connects and use 100% blocking I/O,
		2350	defeating the purpose of an event-based solution. All of the newly
		2351	written AnyEvent benchmarks use 100% non-blocking connects (using
		2352	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2353	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2354	generally require a lot more bookkeeping and event handling than blocking
		2355	connects (which involve a single syscall only).
		2356
		2357	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2358	offers similar expressive power as POE and IO::Lambda, using conventional
		2359	Perl syntax. This means that both the echo server and the client are 100%
		2360	non-blocking, further placing it at a disadvantage.
		2361
		2362	As you can see, the AnyEvent + EV combination even beats the
		2363	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2364	backend easily beats IO::Lambda and POE.
		2365
		2366	And even the 100% non-blocking version written using the high-level (and
		2367	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2368	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2369	in a non-blocking way.
		2370
		2371	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2372	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2373	part of the IO::lambda distribution and were used without any changes.
		2374
		2375
		2376	=head1 SIGNALS
		2377
		2378	AnyEvent currently installs handlers for these signals:
		2379
		2380	=over 4
		2381
		2382	=item SIGCHLD
		2383
		2384	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2385	emulation for event loops that do not support them natively. Also, some
		2386	event loops install a similar handler.
		2387
		2388	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2389	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2390
		2391	=item SIGPIPE
		2392
		2393	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2394	when AnyEvent gets loaded.
		2395
		2396	The rationale for this is that AnyEvent users usually do not really depend
		2397	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2398	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2399	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2400	some random socket.
		2401
		2402	The rationale for installing a no-op handler as opposed to ignoring it is
		2403	that this way, the handler will be restored to defaults on exec.
		2404
		2405	Feel free to install your own handler, or reset it to defaults.
		2406
		2407	=back
		2408
		2409	=cut
		2410
		2411	undef $SIG{CHLD}
		2412	if $SIG{CHLD} eq 'IGNORE';
		2413
		2414	$SIG{PIPE} = sub { }
		2415	unless defined $SIG{PIPE};
		2416
		2417	=head1 RECOMMENDED/OPTIONAL MODULES
		2418
		2419	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2420	it's built-in modules) are required to use it.
		2421
		2422	That does not mean that AnyEvent won't take advantage of some additional
		2423	modules if they are installed.
		2424
		2425	This section epxlains which additional modules will be used, and how they
		2426	affect AnyEvent's operetion.
		2427
		2428	=over 4
		2429
		2430	=item L<Async::Interrupt>
		2431
		2432	This slightly arcane module is used to implement fast signal handling: To
		2433	my knowledge, there is no way to do completely race-free and quick
		2434	signal handling in pure perl. To ensure that signals still get
		2435	delivered, AnyEvent will start an interval timer to wake up perl (and
		2436	catch the signals) with some delay (default is 10 seconds, look for
		2437	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2438
		2439	If this module is available, then it will be used to implement signal
		2440	catching, which means that signals will not be delayed, and the event loop
		2441	will not be interrupted regularly, which is more efficient (And good for
		2442	battery life on laptops).
		2443
		2444	This affects not just the pure-perl event loop, but also other event loops
		2445	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2446
		2447	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2448	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2449	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2450	does nothing for those backends.
		2451
		2452	=item L<EV>
		2453
		2454	This module isn't really "optional", as it is simply one of the backend
		2455	event loops that AnyEvent can use. However, it is simply the best event
		2456	loop available in terms of features, speed and stability: It supports
		2457	the AnyEvent API optimally, implements all the watcher types in XS, does
		2458	automatic timer adjustments even when no monotonic clock is available,
		2459	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2460	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2461	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2462
		2463	=item L<Guard>
		2464
		2465	The guard module, when used, will be used to implement
		2466	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2467	lot less memory), but otherwise doesn't affect guard operation much. It is
		2468	purely used for performance.
		2469
		2470	=item L<JSON> and L<JSON::XS>
		2471
		2472	This module is required when you want to read or write JSON data via
		2473	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2474	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2475
		2476	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2477	installed.
		2478
		2479	=item L<Net::SSLeay>
		2480
		2481	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2482	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2483	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2484
		2485	=item L<Time::HiRes>
		2486
		2487	This module is part of perl since release 5.008. It will be used when the
		2488	chosen event library does not come with a timing source on it's own. The
		2489	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2490	try to use a monotonic clock for timing stability.
		2491
		2492	=back
		2493
1640		2494
1641	=head1 FORK	2495	=head1 FORK
1642		2496
1643	Most event libraries are not fork-safe. The ones who are usually are	2497	Most event libraries are not fork-safe. The ones who are usually are
1644	because they rely on inefficient but fork-safe C<select> or C<poll>	2498	because they rely on inefficient but fork-safe C<select> or C<poll>
1645	calls. Only L<EV> is fully fork-aware.	2499	calls. Only L<EV> is fully fork-aware.
1646		2500
1647	If you have to fork, you must either do so I<before> creating your first	2501	If you have to fork, you must either do so I<before> creating your first
1648	watcher OR you must not use AnyEvent at all in the child.	2502	watcher OR you must not use AnyEvent at all in the child OR you must do
		2503	something completely out of the scope of AnyEvent.
1649		2504
1650		2505
1651	=head1 SECURITY CONSIDERATIONS	2506	=head1 SECURITY CONSIDERATIONS
1652		2507
1653	AnyEvent can be forced to load any event model via	2508	AnyEvent can be forced to load any event model via
…		…
1664		2519
1665	use AnyEvent;	2520	use AnyEvent;
1666		2521
1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2522	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1668	be used to probe what backend is used and gain other information (which is	2523	be used to probe what backend is used and gain other information (which is
1669	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2524	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2525	$ENV{PERL_ANYEVENT_STRICT}.
		2526
		2527	Note that AnyEvent will remove I<all> environment variables starting with
		2528	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2529	enabled.
		2530
		2531
		2532	=head1 BUGS
		2533
		2534	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2535	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2536	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2537	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2538	pronounced).
1670		2539
1671		2540
1672	=head1 SEE ALSO	2541	=head1 SEE ALSO
1673		2542
1674	Utility functions: L<AnyEvent::Util>.	2543	Utility functions: L<AnyEvent::Util>.
…		…
1677	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2546	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1678		2547
1679	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2548	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1680	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2549	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1681	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2550	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1682	L<AnyEvent::Impl::POE>.	2551	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1683		2552
1684	Non-blocking file handles, sockets, TCP clients and	2553	Non-blocking file handles, sockets, TCP clients and
1685	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2554	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1686		2555
1687	Asynchronous DNS: L<AnyEvent::DNS>.	2556	Asynchronous DNS: L<AnyEvent::DNS>.
1688		2557
1689	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2558	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2559	L<Coro::Event>,
1690		2560
1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2561	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2562	L<AnyEvent::HTTP>.
1692		2563
1693		2564
1694	=head1 AUTHOR	2565	=head1 AUTHOR
1695		2566
1696	Marc Lehmann <schmorp@schmorp.de>	2567	Marc Lehmann <schmorp@schmorp.de>

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