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Revision 1.315 by root, Sat Mar 13 00:08:08 2010 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	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		369	when mod_perl executes the script, then the event loop will have the wrong
		370	idea about the "current time" (being potentially far in the past, when the
		371	script ran the last time). In that case you should arrange a call to C<<
		372	AnyEvent->now_update >> each time the web server process wakes up again
		373	(e.g. at the start of your script, or in a handler).
		374
		375	Note that updating the time I<might> cause some events to be handled.
		376
305	=back	377	=back
306		378
307	=head2 SIGNAL WATCHERS	379	=head2 SIGNAL WATCHERS
308		380
		381	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		382
309	You can watch for signals using a signal watcher, C<signal> is the signal	383	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	384	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311	be invoked whenever a signal occurs.	385	callback to be invoked whenever a signal occurs.
312		386
313	Although the callback might get passed parameters, their value and	387	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	388	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	389	callbacks cannot use arguments passed to signal watcher callbacks.
316		390
…		…
318	invocation, and callback invocation will be synchronous. Synchronous means	392	invocation, and callback invocation will be synchronous. Synchronous means
319	that it might take a while until the signal gets handled by the process,	393	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.	394	but it is guaranteed not to interrupt any other callbacks.
321		395
322	The main advantage of using these watchers is that you can share a signal	396	The main advantage of using these watchers is that you can share a signal
323	between multiple watchers.	397	between multiple watchers, and AnyEvent will ensure that signals will not
		398	interrupt your program at bad times.
324		399
325	This watcher might use C<%SIG>, so programs overwriting those signals	400	This watcher might use C<%SIG> (depending on the event loop used),
326	directly will likely not work correctly.	401	so programs overwriting those signals directly will likely not work
		402	correctly.
327		403
328	Example: exit on SIGINT	404	Example: exit on SIGINT
329		405
330	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	406	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		407
		408	=head3 Restart Behaviour
		409
		410	While restart behaviour is up to the event loop implementation, most will
		411	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		412	pure perl implementation).
		413
		414	=head3 Safe/Unsafe Signals
		415
		416	Perl signals can be either "safe" (synchronous to opcode handling) or
		417	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		418	latter might corrupt your memory.
		419
		420	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		421	i.e. they will not interrupt your running perl program but will only be
		422	called as part of the normal event handling (just like timer, I/O etc.
		423	callbacks, too).
		424
		425	=head3 Signal Races, Delays and Workarounds
		426
		427	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		428	callbacks to signals in a generic way, which is a pity, as you cannot
		429	do race-free signal handling in perl, requiring C libraries for
		430	this. AnyEvent will try to do it's best, which means in some cases,
		431	signals will be delayed. The maximum time a signal might be delayed is
		432	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		433	variable can be changed only before the first signal watcher is created,
		434	and should be left alone otherwise. This variable determines how often
		435	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		436	will cause fewer spurious wake-ups, which is better for power and CPU
		437	saving.
		438
		439	All these problems can be avoided by installing the optional
		440	L<Async::Interrupt> module, which works with most event loops. It will not
		441	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		442	(and not with L<POE> currently, as POE does it's own workaround with
		443	one-second latency). For those, you just have to suffer the delays.
		444
332	=head2 CHILD PROCESS WATCHERS	445	=head2 CHILD PROCESS WATCHERS
333		446
		447	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		448
334	You can also watch on a child process exit and catch its exit status.	449	You can also watch on a child process exit and catch its exit status.
335		450
336	The child process is specified by the C<pid> argument (if set to C<0>, it	451	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	452	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	453	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	454	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,	455	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	456
		457	The callback will be called with the pid and exit status (as returned by
		458	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		459	callback arguments.
		460
		461	This watcher type works by installing a signal handler for C<SIGCHLD>,
		462	and since it cannot be shared, nothing else should use SIGCHLD or reap
		463	random child processes (waiting for specific child processes, e.g. inside
		464	C<system>, is just fine).
342		465
343	There is a slight catch to child watchers, however: you usually start them	466	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	467	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	468	have exited already (and no SIGCHLD will be sent anymore).
346		469
347	Not all event models handle this correctly (POE doesn't), but even for	470	Not all event models handle this correctly (neither POE nor IO::Async do,
		471	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	472	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).	473	the process exits (i.e. before you fork in the first place). AnyEvent's
		474	pure perl event loop handles all cases correctly regardless of when you
		475	start the watcher.
350		476
351	This means you cannot create a child watcher as the very first thing in an	477	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	478	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>).	479	watcher before you C<fork> the child (alternatively, you can call
		480	C<AnyEvent::detect>).
		481
		482	As most event loops do not support waiting for child events, they will be
		483	emulated by AnyEvent in most cases, in which the latency and race problems
		484	mentioned in the description of signal watchers apply.
354		485
355	Example: fork a process and wait for it	486	Example: fork a process and wait for it
356		487
357	my $done = AnyEvent->condvar;	488	my $done = AnyEvent->condvar;
358		489
…		…
368	);	499	);
369		500
370	# do something else, then wait for process exit	501	# do something else, then wait for process exit
371	$done->recv;	502	$done->recv;
372		503
		504	=head2 IDLE WATCHERS
		505
		506	$w = AnyEvent->idle (cb => <callback>);
		507
		508	Repeatedly invoke the callback after the process becomes idle, until
		509	either the watcher is destroyed or new events have been detected.
		510
		511	Idle watchers are useful when there is a need to do something, but it
		512	is not so important (or wise) to do it instantly. The callback will be
		513	invoked only when there is "nothing better to do", which is usually
		514	defined as "all outstanding events have been handled and no new events
		515	have been detected". That means that idle watchers ideally get invoked
		516	when the event loop has just polled for new events but none have been
		517	detected. Instead of blocking to wait for more events, the idle watchers
		518	will be invoked.
		519
		520	Unfortunately, most event loops do not really support idle watchers (only
		521	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		522	will simply call the callback "from time to time".
		523
		524	Example: read lines from STDIN, but only process them when the
		525	program is otherwise idle:
		526
		527	my @lines; # read data
		528	my $idle_w;
		529	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		530	push @lines, scalar <STDIN>;
		531
		532	# start an idle watcher, if not already done
		533	$idle_w ||= AnyEvent->idle (cb => sub {
		534	# handle only one line, when there are lines left
		535	if (my $line = shift @lines) {
		536	print "handled when idle: $line";
		537	} else {
		538	# otherwise disable the idle watcher again
		539	undef $idle_w;
		540	}
		541	});
		542	});
		543
373	=head2 CONDITION VARIABLES	544	=head2 CONDITION VARIABLES
		545
		546	$cv = AnyEvent->condvar;
		547
		548	$cv->send (<list>);
		549	my @res = $cv->recv;
374		550
375	If you are familiar with some event loops you will know that all of them	551	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	552	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	553	will actively watch for new events and call your callbacks.
378		554
379	AnyEvent is different, it expects somebody else to run the event loop and	555	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	556	loop and will only block when necessary (usually when told by the user).
381		557
382	The instrument to do that is called a "condition variable", so called	558	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	559	because they represent a condition that must become true.
		560
		561	Now is probably a good time to look at the examples further below.
384		562
385	Condition variables can be created by calling the C<< AnyEvent->condvar	563	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	564	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	565	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	566	becomes true, with the condition variable as the first argument (but not
		567	the results).
389		568
390	After creation, the condition variable is "false" until it becomes "true"	569	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	570	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<<	571	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	572	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	574	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	575	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	576	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	577	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	578	used to represent a transaction, which finishes at some point and delivers
400	a result.	579	a result. And yet some people know them as "futures" - a promise to
		580	compute/deliver something that you can wait for.
401		581
402	Condition variables are very useful to signal that something has finished,	582	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	583	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	584	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	585	availability of results. The user can either act when the callback is
…		…
439	after => 1,	619	after => 1,
440	cb => sub { $result_ready->send },	620	cb => sub { $result_ready->send },
441	);	621	);
442		622
443	# this "blocks" (while handling events) till the callback	623	# this "blocks" (while handling events) till the callback
444	# calls send	624	# calls ->send
445	$result_ready->recv;	625	$result_ready->recv;
446		626
447	Example: wait for a timer, but take advantage of the fact that	627	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	628	variables are also callable directly.
449		629
450	my $done = AnyEvent->condvar;	630	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	631	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	632	$done->recv;
		633
		634	Example: Imagine an API that returns a condvar and doesn't support
		635	callbacks. This is how you make a synchronous call, for example from
		636	the main program:
		637
		638	use AnyEvent::CouchDB;
		639
		640	...
		641
		642	my @info = $couchdb->info->recv;
		643
		644	And this is how you would just set a callback to be called whenever the
		645	results are available:
		646
		647	$couchdb->info->cb (sub {
		648	my @info = $_[0]->recv;
		649	});
453		650
454	=head3 METHODS FOR PRODUCERS	651	=head3 METHODS FOR PRODUCERS
455		652
456	These methods should only be used by the producing side, i.e. the	653	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	654	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	667	immediately from within send.
471		668
472	Any arguments passed to the C<send> call will be returned by all	669	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	670	future C<< ->recv >> calls.
474		671
475	Condition variables are overloaded so one can call them directly	672	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	673	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	674	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		675
484	=item $cv->croak ($error)	676	=item $cv->croak ($error)
485		677
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	678	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	679	C<Carp::croak> with the given error message/object/scalar.
488		680
489	This can be used to signal any errors to the condition variable	681	This can be used to signal any errors to the condition variable
490	user/consumer.	682	user/consumer. Doing it this way instead of calling C<croak> directly
		683	delays the error detetcion, but has the overwhelmign advantage that it
		684	diagnoses the error at the place where the result is expected, and not
		685	deep in some event clalback without connection to the actual code causing
		686	the problem.
491		687
492	=item $cv->begin ([group callback])	688	=item $cv->begin ([group callback])
493		689
494	=item $cv->end	690	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		691
498	These two methods can be used to combine many transactions/events into	692	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	693	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	694	to use a condition variable for the whole process.
501		695
502	Every call to C<< ->begin >> will increment a counter, and every call to	696	Every call to C<< ->begin >> will increment a counter, and every call to
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	697	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	698	>>, the (last) callback passed to C<begin> will be executed, passing the
505	is I<supposed> to call C<< ->send >>, but that is not required. If no	699	condvar as first argument. That callback is I<supposed> to call C<< ->send
506	callback was set, C<send> will be called without any arguments.	700	>>, but that is not required. If no group callback was set, C<send> will
		701	be called without any arguments.
507		702
508	Let's clarify this with the ping example:	703	You can think of C<< $cv->send >> giving you an OR condition (one call
		704	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		705	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		706
		707	Let's start with a simple example: you have two I/O watchers (for example,
		708	STDOUT and STDERR for a program), and you want to wait for both streams to
		709	close before activating a condvar:
509		710
510	my $cv = AnyEvent->condvar;	711	my $cv = AnyEvent->condvar;
511		712
		713	$cv->begin; # first watcher
		714	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		715	defined sysread $fh1, my $buf, 4096
		716	or $cv->end;
		717	});
		718
		719	$cv->begin; # second watcher
		720	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		721	defined sysread $fh2, my $buf, 4096
		722	or $cv->end;
		723	});
		724
		725	$cv->recv;
		726
		727	This works because for every event source (EOF on file handle), there is
		728	one call to C<begin>, so the condvar waits for all calls to C<end> before
		729	sending.
		730
		731	The ping example mentioned above is slightly more complicated, as the
		732	there are results to be passwd back, and the number of tasks that are
		733	begung can potentially be zero:
		734
		735	my $cv = AnyEvent->condvar;
		736
512	my %result;	737	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	738	$cv->begin (sub { shift->send (\%result) });
514		739
515	for my $host (@list_of_hosts) {	740	for my $host (@list_of_hosts) {
516	$cv->begin;	741	$cv->begin;
517	ping_host_then_call_callback $host, sub {	742	ping_host_then_call_callback $host, sub {
518	$result{$host} = ...;	743	$result{$host} = ...;
…		…
533	loop, which serves two important purposes: first, it sets the callback	758	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	759	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	760	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	761	doesn't execute once).
537		762
538	This is the general pattern when you "fan out" into multiple subrequests:	763	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>	764	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	765	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>.	766	subrequest you start, call C<begin> and for each subrequest you finish,
		767	call C<end>.
542		768
543	=back	769	=back
544		770
545	=head3 METHODS FOR CONSUMERS	771	=head3 METHODS FOR CONSUMERS
546		772
…		…
562	function will call C<croak>.	788	function will call C<croak>.
563		789
564	In list context, all parameters passed to C<send> will be returned,	790	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	791	in scalar context only the first one will be returned.
566		792
		793	Note that doing a blocking wait in a callback is not supported by any
		794	event loop, that is, recursive invocation of a blocking C<< ->recv
		795	>> is not allowed, and the C<recv> call will C<croak> if such a
		796	condition is detected. This condition can be slightly loosened by using
		797	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		798	any thread that doesn't run the event loop itself.
		799
567	Not all event models support a blocking wait - some die in that case	800	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	801	(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	802	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	803	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	804	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	805	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	806	while still supporting blocking waits if the caller so desires).
574		807
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	808	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	809	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	810	time). This will work even when the event loop does not support blocking
589	waits otherwise.	811	waits otherwise.
590		812
591	=item $bool = $cv->ready	813	=item $bool = $cv->ready
592		814
593	Returns true when the condition is "true", i.e. whether C<send> or	815	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	816	C<croak> have been called.
595		817
596	=item $cb = $cv->cb ([new callback])	818	=item $cb = $cv->cb ($cb->($cv))
597		819
598	This is a mutator function that returns the callback set and optionally	820	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	821	replaces it before doing so.
600		822
601	The callback will be called when the condition becomes "true", i.e. when	823	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	824	"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	825	the only argument being the condition variable itself. Calling C<recv>
604	is guaranteed not to block.	826	inside the callback or at any later time is guaranteed not to block.
605		827
606	=back	828	=back
607		829
		830	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		831
		832	The available backend classes are (every class has its own manpage):
		833
		834	=over 4
		835
		836	=item Backends that are autoprobed when no other event loop can be found.
		837
		838	EV is the preferred backend when no other event loop seems to be in
		839	use. If EV is not installed, then AnyEvent will fall back to its own
		840	pure-perl implementation, which is available everywhere as it comes with
		841	AnyEvent itself.
		842
		843	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		844	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		845
		846	=item Backends that are transparently being picked up when they are used.
		847
		848	These will be used when they are currently loaded when the first watcher
		849	is created, in which case it is assumed that the application is using
		850	them. This means that AnyEvent will automatically pick the right backend
		851	when the main program loads an event module before anything starts to
		852	create watchers. Nothing special needs to be done by the main program.
		853
		854	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		855	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		856	AnyEvent::Impl::Tk based on Tk, very broken.
		857	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		858	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		859	AnyEvent::Impl::Irssi used when running within irssi.
		860
		861	=item Backends with special needs.
		862
		863	Qt requires the Qt::Application to be instantiated first, but will
		864	otherwise be picked up automatically. As long as the main program
		865	instantiates the application before any AnyEvent watchers are created,
		866	everything should just work.
		867
		868	AnyEvent::Impl::Qt based on Qt.
		869
		870	Support for IO::Async can only be partial, as it is too broken and
		871	architecturally limited to even support the AnyEvent API. It also
		872	is the only event loop that needs the loop to be set explicitly, so
		873	it can only be used by a main program knowing about AnyEvent. See
		874	L<AnyEvent::Impl::Async> for the gory details.
		875
		876	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		877
		878	=item Event loops that are indirectly supported via other backends.
		879
		880	Some event loops can be supported via other modules:
		881
		882	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		883
		884	B<WxWidgets> has no support for watching file handles. However, you can
		885	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		886	polls 20 times per second, which was considered to be too horrible to even
		887	consider for AnyEvent.
		888
		889	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		890	backend, so it can be supported through POE.
		891
		892	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		893	load L<POE> when detecting them, in the hope that POE will pick them up,
		894	in which case everything will be automatic.
		895
		896	=back
		897
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	898	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		899
		900	These are not normally required to use AnyEvent, but can be useful to
		901	write AnyEvent extension modules.
		902
610	=over 4	903	=over 4
611		904
612	=item $AnyEvent::MODEL	905	=item $AnyEvent::MODEL
613		906
614	Contains C<undef> until the first watcher is being created. Then it	907	Contains C<undef> until the first watcher is being created, before the
		908	backend has been autodetected.
		909
615	contains the event model that is being used, which is the name of the	910	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	911	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	912	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	913	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		914	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		915
641	=item AnyEvent::detect	916	=item AnyEvent::detect
642		917
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	918	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	919	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	920	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	921	runtime, and not e.g. while initialising of your module.
		922
		923	If you need to do some initialisation before AnyEvent watchers are
		924	created, use C<post_detect>.
647		925
648	=item $guard = AnyEvent::post_detect { BLOCK }	926	=item $guard = AnyEvent::post_detect { BLOCK }
649		927
650	Arranges for the code block to be executed as soon as the event model is	928	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	929	autodetected (or immediately if this has already happened).
652		930
		931	The block will be executed I<after> the actual backend has been detected
		932	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		933	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		934	other initialisations - see the sources of L<AnyEvent::Strict> or
		935	L<AnyEvent::AIO> to see how this is used.
		936
		937	The most common usage is to create some global watchers, without forcing
		938	event module detection too early, for example, L<AnyEvent::AIO> creates
		939	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		940	avoid autodetecting the event module at load time.
		941
653	If called in scalar or list context, then it creates and returns an object	942	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	943	that automatically removes the callback again when it is destroyed (or
		944	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	945	a case where this is useful.
		946
		947	Example: Create a watcher for the IO::AIO module and store it in
		948	C<$WATCHER>. Only do so after the event loop is initialised, though.
		949
		950	our WATCHER;
		951
		952	my $guard = AnyEvent::post_detect {
		953	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		954	};
		955
		956	# the ||= is important in case post_detect immediately runs the block,
		957	# as to not clobber the newly-created watcher. assigning both watcher and
		958	# post_detect guard to the same variable has the advantage of users being
		959	# able to just C<undef $WATCHER> if the watcher causes them grief.
		960
		961	$WATCHER ||= $guard;
656		962
657	=item @AnyEvent::post_detect	963	=item @AnyEvent::post_detect
658		964
659	If there are any code references in this array (you can C<push> to it	965	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	966	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	967	the event loop has been chosen.
662		968
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	969	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,	970	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	971	array will be ignored.
666		972
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	973	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		974	it, as it takes care of these details.
		975
		976	This variable is mainly useful for modules that can do something useful
		977	when AnyEvent is used and thus want to know when it is initialised, but do
		978	not need to even load it by default. This array provides the means to hook
		979	into AnyEvent passively, without loading it.
		980
		981	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		982	together, you could put this into Coro (this is the actual code used by
		983	Coro to accomplish this):
		984
		985	if (defined $AnyEvent::MODEL) {
		986	# AnyEvent already initialised, so load Coro::AnyEvent
		987	require Coro::AnyEvent;
		988	} else {
		989	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		990	# as soon as it is
		991	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		992	}
668		993
669	=back	994	=back
670		995
671	=head1 WHAT TO DO IN A MODULE	996	=head1 WHAT TO DO IN A MODULE
672		997
…		…
727		1052
728		1053
729	=head1 OTHER MODULES	1054	=head1 OTHER MODULES
730		1055
731	The following is a non-exhaustive list of additional modules that use	1056	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1057	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	1058	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1059	come with AnyEvent, most are available via CPAN.
735		1060
736	=over 4	1061	=over 4
737		1062
738	=item L<AnyEvent::Util>	1063	=item L<AnyEvent::Util>
739		1064
740	Contains various utility functions that replace often-used but blocking	1065	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1066	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		1067
747	=item L<AnyEvent::Socket>	1068	=item L<AnyEvent::Socket>
748		1069
749	Provides various utility functions for (internet protocol) sockets,	1070	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1071	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1072	connections or tcp servers, with IPv6 and SRV record support and more.
752		1073
		1074	=item L<AnyEvent::Handle>
		1075
		1076	Provide read and write buffers, manages watchers for reads and writes,
		1077	supports raw and formatted I/O, I/O queued and fully transparent and
		1078	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1079
753	=item L<AnyEvent::DNS>	1080	=item L<AnyEvent::DNS>
754		1081
755	Provides rich asynchronous DNS resolver capabilities.	1082	Provides rich asynchronous DNS resolver capabilities.
756		1083
757	=item L<AnyEvent::HTTP>	1084	=item L<AnyEvent::HTTP>
…		…
765		1092
766	=item L<AnyEvent::FastPing>	1093	=item L<AnyEvent::FastPing>
767		1094
768	The fastest ping in the west.	1095	The fastest ping in the west.
769		1096
		1097	=item L<AnyEvent::DBI>
		1098
		1099	Executes L<DBI> requests asynchronously in a proxy process.
		1100
		1101	=item L<AnyEvent::AIO>
		1102
		1103	Truly asynchronous I/O, should be in the toolbox of every event
		1104	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1105	together.
		1106
		1107	=item L<AnyEvent::BDB>
		1108
		1109	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1110	L<BDB> and AnyEvent together.
		1111
		1112	=item L<AnyEvent::GPSD>
		1113
		1114	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1115
770	=item L<Net::IRC3>	1116	=item L<AnyEvent::IRC>
771		1117
772	AnyEvent based IRC client module family.	1118	AnyEvent based IRC client module family (replacing the older Net::IRC3).
773		1119
774	=item L<Net::XMPP2>	1120	=item L<AnyEvent::XMPP>
775		1121
776	AnyEvent based XMPP (Jabber protocol) module family.	1122	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1123	Net::XMPP2>.
		1124
		1125	=item L<AnyEvent::IGS>
		1126
		1127	A non-blocking interface to the Internet Go Server protocol (used by
		1128	L<App::IGS>).
777		1129
778	=item L<Net::FCP>	1130	=item L<Net::FCP>
779		1131
780	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1132	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
781	of AnyEvent.	1133	of AnyEvent.
…		…
786		1138
787	=item L<Coro>	1139	=item L<Coro>
788		1140
789	Has special support for AnyEvent via L<Coro::AnyEvent>.	1141	Has special support for AnyEvent via L<Coro::AnyEvent>.
790		1142
791	=item L<AnyEvent::AIO>, L<IO::AIO>
792
793	Truly asynchronous I/O, should be in the toolbox of every event
794	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
795	together.
796
797	=item L<AnyEvent::BDB>, L<BDB>
798
799	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
800	IO::AIO and AnyEvent together.
801
802	=item L<IO::Lambda>
803
804	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
805
806	=back	1143	=back
807		1144
808	=cut	1145	=cut
809		1146
810	package AnyEvent;	1147	package AnyEvent;
811		1148
812	no warnings;	1149	# basically a tuned-down version of common::sense
813	use strict;	1150	sub common_sense {
		1151	# from common:.sense 1.0
		1152	${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
		1153	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1154	$^H |= 0x00000600;
		1155	}
814		1156
		1157	BEGIN { AnyEvent::common_sense }
		1158
815	use Carp;	1159	use Carp ();
816		1160
817	our $VERSION = 4.14;	1161	our $VERSION = '5.251';
818	our $MODEL;	1162	our $MODEL;
819		1163
820	our $AUTOLOAD;	1164	our $AUTOLOAD;
821	our @ISA;	1165	our @ISA;
822		1166
823	our @REGISTRY;	1167	our @REGISTRY;
824		1168
825	our $WIN32;	1169	our $VERBOSE;
826		1170
827	BEGIN {	1171	BEGIN {
828	my $win32 = ! ! ($^O =~ /mswin32/i);	1172	require "AnyEvent/constants.pl";
829	eval "sub WIN32(){ $win32 }";
830	}
831		1173
		1174	eval "sub TAINT (){" . (${^TAINT} *1) . "}";
		1175
		1176	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1177	if ${^TAINT};
		1178
832	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1179	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1180
		1181	}
		1182
		1183	our $MAX_SIGNAL_LATENCY = 10;
833		1184
834	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1185	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
835		1186
836	{	1187	{
837	my $idx;	1188	my $idx;
…		…
839	for reverse split /\s*,\s*/,	1190	for reverse split /\s*,\s*/,
840	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1191	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
841	}	1192	}
842		1193
843	my @models = (	1194	my @models = (
844	[EV:: => AnyEvent::Impl::EV::],	1195	[EV:: => AnyEvent::Impl::EV:: , 1],
845	[Event:: => AnyEvent::Impl::Event::],
846	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1196	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
847	# everything below here will not be autoprobed	1197	# everything below here will not (normally) be autoprobed
848	# as the pureperl backend should work everywhere	1198	# as the pureperl backend should work everywhere
849	# and is usually faster	1199	# and is usually faster
		1200	[Event:: => AnyEvent::Impl::Event::, 1],
		1201	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1202	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1203	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
850	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1204	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
851	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
852	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
853	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1205	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
854	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1206	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
855	[Wx:: => AnyEvent::Impl::POE::],	1207	[Wx:: => AnyEvent::Impl::POE::],
856	[Prima:: => AnyEvent::Impl::POE::],	1208	[Prima:: => AnyEvent::Impl::POE::],
		1209	# IO::Async is just too broken - we would need workarounds for its
		1210	# byzantine signal and broken child handling, among others.
		1211	# IO::Async is rather hard to detect, as it doesn't have any
		1212	# obvious default class.
		1213	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1214	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1215	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1216	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
857	);	1217	);
858		1218
859	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1219	our %method = map +($_ => 1),
		1220	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
860		1221
861	our @post_detect;	1222	our @post_detect;
862		1223
863	sub post_detect(&) {	1224	sub post_detect(&) {
864	my ($cb) = @_;	1225	my ($cb) = @_;
865		1226
866	if ($MODEL) {	1227	if ($MODEL) {
867	$cb->();	1228	$cb->();
868		1229
869	1	1230	undef
870	} else {	1231	} else {
871	push @post_detect, $cb;	1232	push @post_detect, $cb;
872		1233
873	defined wantarray	1234	defined wantarray
874	? bless \$cb, "AnyEvent::Util::PostDetect"	1235	? bless \$cb, "AnyEvent::Util::postdetect"
875	: ()	1236	: ()
876	}	1237	}
877	}	1238	}
878		1239
879	sub AnyEvent::Util::PostDetect::DESTROY {	1240	sub AnyEvent::Util::postdetect::DESTROY {
880	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1241	@post_detect = grep $_ != ${$_[0]}, @post_detect;
881	}	1242	}
882		1243
883	sub detect() {	1244	sub detect() {
		1245	# free some memory
		1246	*detect = sub () { $MODEL };
		1247
		1248	local $!; # for good measure
		1249	local $SIG{__DIE__};
		1250
		1251	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1252	my $model = "AnyEvent::Impl::$1";
		1253	if (eval "require $model") {
		1254	$MODEL = $model;
		1255	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1256	} else {
		1257	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1258	}
		1259	}
		1260
		1261	# check for already loaded models
884	unless ($MODEL) {	1262	unless ($MODEL) {
885	no strict 'refs';	1263	for (@REGISTRY, @models) {
886	local $SIG{__DIE__};	1264	my ($package, $model) = @$_;
887		1265	if (${"$package\::VERSION"} > 0) {
888	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
889	my $model = "AnyEvent::Impl::$1";
890	if (eval "require $model") {	1266	if (eval "require $model") {
891	$MODEL = $model;	1267	$MODEL = $model;
892	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1268	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
893	} else {	1269	last;
894	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1270	}
895	}	1271	}
896	}	1272	}
897		1273
898	# check for already loaded models
899	unless ($MODEL) {	1274	unless ($MODEL) {
		1275	# try to autoload a model
900	for (@REGISTRY, @models) {	1276	for (@REGISTRY, @models) {
901	my ($package, $model) = @$_;	1277	my ($package, $model, $autoload) = @$_;
		1278	if (
		1279	$autoload
		1280	and eval "require $package"
902	if (${"$package\::VERSION"} > 0) {	1281	and ${"$package\::VERSION"} > 0
903	if (eval "require $model") {	1282	and eval "require $model"
		1283	) {
904	$MODEL = $model;	1284	$MODEL = $model;
905	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1285	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
906	last;	1286	last;
907	}
908	}	1287	}
909	}	1288	}
910		1289
911	unless ($MODEL) {
912	# try to load a model
913
914	for (@REGISTRY, @models) {
915	my ($package, $model) = @$_;
916	if (eval "require $package"
917	and ${"$package\::VERSION"} > 0
918	and eval "require $model") {
919	$MODEL = $model;
920	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
921	last;
922	}
923	}
924
925	$MODEL	1290	$MODEL
926	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1291	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
927	}
928	}	1292	}
929
930	unshift @ISA, $MODEL;
931	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
932
933	(shift @post_detect)->() while @post_detect;
934	}	1293	}
		1294
		1295	@models = (); # free probe data
		1296
		1297	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1298	unshift @ISA, $MODEL;
		1299
		1300	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1301
		1302	(shift @post_detect)->() while @post_detect;
935		1303
936	$MODEL	1304	$MODEL
937	}	1305	}
938		1306
939	sub AUTOLOAD {	1307	sub AUTOLOAD {
940	(my $func = $AUTOLOAD) =~ s/.*://;	1308	(my $func = $AUTOLOAD) =~ s/.*://;
941		1309
942	$method{$func}	1310	$method{$func}
943	or croak "$func: not a valid method for AnyEvent objects";	1311	or Carp::croak "$func: not a valid AnyEvent class method";
944		1312
945	detect unless $MODEL;	1313	detect;
946		1314
947	my $class = shift;	1315	my $class = shift;
948	$class->$func (@_);	1316	$class->$func (@_);
949	}	1317	}
950		1318
		1319	# utility function to dup a filehandle. this is used by many backends
		1320	# to support binding more than one watcher per filehandle (they usually
		1321	# allow only one watcher per fd, so we dup it to get a different one).
		1322	sub _dupfh($$;$$) {
		1323	my ($poll, $fh, $r, $w) = @_;
		1324
		1325	# cygwin requires the fh mode to be matching, unix doesn't
		1326	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1327
		1328	open my $fh2, $mode, $fh
		1329	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1330
		1331	# we assume CLOEXEC is already set by perl in all important cases
		1332
		1333	($fh2, $rw)
		1334	}
		1335
		1336	=head1 SIMPLIFIED AE API
		1337
		1338	Starting with version 5.0, AnyEvent officially supports a second, much
		1339	simpler, API that is designed to reduce the calling, typing and memory
		1340	overhead.
		1341
		1342	See the L<AE> manpage for details.
		1343
		1344	=cut
		1345
		1346	package AE;
		1347
		1348	our $VERSION = $AnyEvent::VERSION;
		1349
		1350	sub io($$$) {
		1351	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1352	}
		1353
		1354	sub timer($$$) {
		1355	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1356	}
		1357
		1358	sub signal($$) {
		1359	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1360	}
		1361
		1362	sub child($$) {
		1363	AnyEvent->child (pid => $_[0], cb => $_[1])
		1364	}
		1365
		1366	sub idle($) {
		1367	AnyEvent->idle (cb => $_[0])
		1368	}
		1369
		1370	sub cv(;&) {
		1371	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1372	}
		1373
		1374	sub now() {
		1375	AnyEvent->now
		1376	}
		1377
		1378	sub now_update() {
		1379	AnyEvent->now_update
		1380	}
		1381
		1382	sub time() {
		1383	AnyEvent->time
		1384	}
		1385
951	package AnyEvent::Base;	1386	package AnyEvent::Base;
952		1387
953	# default implementation for now and time	1388	# default implementations for many methods
954		1389
955	use Time::HiRes ();	1390	sub _time() {
		1391	eval q{ # poor man's autoloading
		1392	# probe for availability of Time::HiRes
		1393	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1394	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1395	*_time = \&Time::HiRes::time;
		1396	# if (eval "use POSIX (); (POSIX::times())...
		1397	} else {
		1398	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1399	*_time = sub (){ time }; # epic fail
		1400	}
		1401	};
		1402	die if $@;
956		1403
957	sub time { Time::HiRes::time }	1404	&_time
958	sub now { Time::HiRes::time }	1405	}
		1406
		1407	sub time { _time }
		1408	sub now { _time }
		1409	sub now_update { }
959		1410
960	# default implementation for ->condvar	1411	# default implementation for ->condvar
961		1412
962	sub condvar {	1413	sub condvar {
963	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1414	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
964	}	1415	}
965		1416
966	# default implementation for ->signal	1417	# default implementation for ->signal
967		1418
968	our %SIG_CB;	1419	our $HAVE_ASYNC_INTERRUPT;
		1420
		1421	sub _have_async_interrupt() {
		1422	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1423	&& eval "use Async::Interrupt 1.02 (); 1")
		1424	unless defined $HAVE_ASYNC_INTERRUPT;
		1425
		1426	$HAVE_ASYNC_INTERRUPT
		1427	}
		1428
		1429	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1430	our (%SIG_ASY, %SIG_ASY_W);
		1431	our ($SIG_COUNT, $SIG_TW);
		1432
		1433	# install a dummy wakeup watcher to reduce signal catching latency
		1434	# used by Impls
		1435	sub _sig_add() {
		1436	unless ($SIG_COUNT++) {
		1437	# try to align timer on a full-second boundary, if possible
		1438	my $NOW = AE::now;
		1439
		1440	$SIG_TW = AE::timer
		1441	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1442	$MAX_SIGNAL_LATENCY,
		1443	sub { } # just for the PERL_ASYNC_CHECK
		1444	;
		1445	}
		1446	}
		1447
		1448	sub _sig_del {
		1449	undef $SIG_TW
		1450	unless --$SIG_COUNT;
		1451	}
		1452
		1453	our $_sig_name_init; $_sig_name_init = sub {
		1454	eval q{ # poor man's autoloading
		1455	undef $_sig_name_init;
		1456
		1457	if (_have_async_interrupt) {
		1458	*sig2num = \&Async::Interrupt::sig2num;
		1459	*sig2name = \&Async::Interrupt::sig2name;
		1460	} else {
		1461	require Config;
		1462
		1463	my %signame2num;
		1464	@signame2num{ split ' ', $Config::Config{sig_name} }
		1465	= split ' ', $Config::Config{sig_num};
		1466
		1467	my @signum2name;
		1468	@signum2name[values %signame2num] = keys %signame2num;
		1469
		1470	*sig2num = sub($) {
		1471	$_[0] > 0 ? shift : $signame2num{+shift}
		1472	};
		1473	*sig2name = sub ($) {
		1474	$_[0] > 0 ? $signum2name[+shift] : shift
		1475	};
		1476	}
		1477	};
		1478	die if $@;
		1479	};
		1480
		1481	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1482	sub sig2name($) { &$_sig_name_init; &sig2name }
969		1483
970	sub signal {	1484	sub signal {
		1485	eval q{ # poor man's autoloading {}
		1486	# probe for availability of Async::Interrupt
		1487	if (_have_async_interrupt) {
		1488	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1489
		1490	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1491	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1492
		1493	} else {
		1494	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1495
		1496	if (AnyEvent::WIN32) {
		1497	require AnyEvent::Util;
		1498
		1499	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1500	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1501	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1502	} else {
		1503	pipe $SIGPIPE_R, $SIGPIPE_W;
		1504	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1505	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1506
		1507	# not strictly required, as $^F is normally 2, but let's make sure...
		1508	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1509	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1510	}
		1511
		1512	$SIGPIPE_R
		1513	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1514
		1515	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1516	}
		1517
		1518	*signal = sub {
971	my (undef, %arg) = @_;	1519	my (undef, %arg) = @_;
972		1520
973	my $signal = uc $arg{signal}	1521	my $signal = uc $arg{signal}
974	or Carp::croak "required option 'signal' is missing";	1522	or Carp::croak "required option 'signal' is missing";
975		1523
		1524	if ($HAVE_ASYNC_INTERRUPT) {
		1525	# async::interrupt
		1526
		1527	$signal = sig2num $signal;
976	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1528	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1529
		1530	$SIG_ASY{$signal} ||= new Async::Interrupt
		1531	cb => sub { undef $SIG_EV{$signal} },
		1532	signal => $signal,
		1533	pipe => [$SIGPIPE_R->filenos],
		1534	pipe_autodrain => 0,
		1535	;
		1536
		1537	} else {
		1538	# pure perl
		1539
		1540	# AE::Util has been loaded in signal
		1541	$signal = sig2name $signal;
		1542	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1543
977	$SIG{$signal} ||= sub {	1544	$SIG{$signal} ||= sub {
		1545	local $!;
		1546	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1547	undef $SIG_EV{$signal};
		1548	};
		1549
		1550	# can't do signal processing without introducing races in pure perl,
		1551	# so limit the signal latency.
		1552	_sig_add;
		1553	}
		1554
		1555	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1556	};
		1557
		1558	*AnyEvent::Base::signal::DESTROY = sub {
		1559	my ($signal, $cb) = @{$_[0]};
		1560
		1561	_sig_del;
		1562
		1563	delete $SIG_CB{$signal}{$cb};
		1564
		1565	$HAVE_ASYNC_INTERRUPT
		1566	? delete $SIG_ASY{$signal}
		1567	: # delete doesn't work with older perls - they then
		1568	# print weird messages, or just unconditionally exit
		1569	# instead of getting the default action.
		1570	undef $SIG{$signal}
		1571	unless keys %{ $SIG_CB{$signal} };
		1572	};
		1573
		1574	*_signal_exec = sub {
		1575	$HAVE_ASYNC_INTERRUPT
		1576	? $SIGPIPE_R->drain
		1577	: sysread $SIGPIPE_R, (my $dummy), 9;
		1578
		1579	while (%SIG_EV) {
		1580	for (keys %SIG_EV) {
		1581	delete $SIG_EV{$_};
978	$_->() for values %{ $SIG_CB{$signal} || {} };	1582	$_->() for values %{ $SIG_CB{$_} || {} };
		1583	}
		1584	}
		1585	};
979	};	1586	};
		1587	die if $@;
980		1588
981	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1589	&signal
982	}
983
984	sub AnyEvent::Base::Signal::DESTROY {
985	my ($signal, $cb) = @{$_[0]};
986
987	delete $SIG_CB{$signal}{$cb};
988
989	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
990	}	1590	}
991		1591
992	# default implementation for ->child	1592	# default implementation for ->child
993		1593
994	our %PID_CB;	1594	our %PID_CB;
995	our $CHLD_W;	1595	our $CHLD_W;
996	our $CHLD_DELAY_W;	1596	our $CHLD_DELAY_W;
997	our $PID_IDLE;
998	our $WNOHANG;	1597	our $WNOHANG;
999		1598
1000	sub _child_wait {	1599	# used by many Impl's
1001	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1600	sub _emit_childstatus($$) {
		1601	my (undef, $rpid, $rstatus) = @_;
		1602
		1603	$_->($rpid, $rstatus)
1002	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1604	for values %{ $PID_CB{$rpid} || {} },
1003	(values %{ $PID_CB{0} || {} });	1605	values %{ $PID_CB{0} || {} };
1004	}
1005
1006	undef $PID_IDLE;
1007	}
1008
1009	sub _sigchld {
1010	# make sure we deliver these changes "synchronous" with the event loop.
1011	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1012	undef $CHLD_DELAY_W;
1013	&_child_wait;
1014	});
1015	}	1606	}
1016		1607
1017	sub child {	1608	sub child {
		1609	eval q{ # poor man's autoloading {}
		1610	*_sigchld = sub {
		1611	my $pid;
		1612
		1613	AnyEvent->_emit_childstatus ($pid, $?)
		1614	while ($pid = waitpid -1, $WNOHANG) > 0;
		1615	};
		1616
		1617	*child = sub {
1018	my (undef, %arg) = @_;	1618	my (undef, %arg) = @_;
1019		1619
1020	defined (my $pid = $arg{pid} + 0)	1620	defined (my $pid = $arg{pid} + 0)
1021	or Carp::croak "required option 'pid' is missing";	1621	or Carp::croak "required option 'pid' is missing";
1022		1622
1023	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1623	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1024		1624
1025	unless ($WNOHANG) {	1625	# WNOHANG is almost cetrainly 1 everywhere
		1626	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1627	? 1
1026	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1628	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1027	}
1028		1629
1029	unless ($CHLD_W) {	1630	unless ($CHLD_W) {
1030	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1631	$CHLD_W = AE::signal CHLD => \&_sigchld;
1031	# child could be a zombie already, so make at least one round	1632	# child could be a zombie already, so make at least one round
1032	&_sigchld;	1633	&_sigchld;
1033	}	1634	}
1034		1635
1035	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1636	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1036	}	1637	};
1037		1638
1038	sub AnyEvent::Base::Child::DESTROY {	1639	*AnyEvent::Base::child::DESTROY = sub {
1039	my ($pid, $cb) = @{$_[0]};	1640	my ($pid, $cb) = @{$_[0]};
1040		1641
1041	delete $PID_CB{$pid}{$cb};	1642	delete $PID_CB{$pid}{$cb};
1042	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1643	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1043		1644
1044	undef $CHLD_W unless keys %PID_CB;	1645	undef $CHLD_W unless keys %PID_CB;
		1646	};
		1647	};
		1648	die if $@;
		1649
		1650	&child
		1651	}
		1652
		1653	# idle emulation is done by simply using a timer, regardless
		1654	# of whether the process is idle or not, and not letting
		1655	# the callback use more than 50% of the time.
		1656	sub idle {
		1657	eval q{ # poor man's autoloading {}
		1658	*idle = sub {
		1659	my (undef, %arg) = @_;
		1660
		1661	my ($cb, $w, $rcb) = $arg{cb};
		1662
		1663	$rcb = sub {
		1664	if ($cb) {
		1665	$w = _time;
		1666	&$cb;
		1667	$w = _time - $w;
		1668
		1669	# never use more then 50% of the time for the idle watcher,
		1670	# within some limits
		1671	$w = 0.0001 if $w < 0.0001;
		1672	$w = 5 if $w > 5;
		1673
		1674	$w = AE::timer $w, 0, $rcb;
		1675	} else {
		1676	# clean up...
		1677	undef $w;
		1678	undef $rcb;
		1679	}
		1680	};
		1681
		1682	$w = AE::timer 0.05, 0, $rcb;
		1683
		1684	bless \\$cb, "AnyEvent::Base::idle"
		1685	};
		1686
		1687	*AnyEvent::Base::idle::DESTROY = sub {
		1688	undef $${$_[0]};
		1689	};
		1690	};
		1691	die if $@;
		1692
		1693	&idle
1045	}	1694	}
1046		1695
1047	package AnyEvent::CondVar;	1696	package AnyEvent::CondVar;
1048		1697
1049	our @ISA = AnyEvent::CondVar::Base::;	1698	our @ISA = AnyEvent::CondVar::Base::;
1050		1699
1051	package AnyEvent::CondVar::Base;	1700	package AnyEvent::CondVar::Base;
1052		1701
1053	use overload	1702	#use overload
1054	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1703	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1055	fallback => 1;	1704	# fallback => 1;
		1705
		1706	# save 300+ kilobytes by dirtily hardcoding overloading
		1707	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1708	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1709	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1710	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1711
		1712	our $WAITING;
1056		1713
1057	sub _send {	1714	sub _send {
1058	# nop	1715	# nop
1059	}	1716	}
1060		1717
…		…
1073	sub ready {	1730	sub ready {
1074	$_[0]{_ae_sent}	1731	$_[0]{_ae_sent}
1075	}	1732	}
1076		1733
1077	sub _wait {	1734	sub _wait {
		1735	$WAITING
		1736	and !$_[0]{_ae_sent}
		1737	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1738
		1739	local $WAITING = 1;
1078	AnyEvent->one_event while !$_[0]{_ae_sent};	1740	AnyEvent->one_event while !$_[0]{_ae_sent};
1079	}	1741	}
1080		1742
1081	sub recv {	1743	sub recv {
1082	$_[0]->_wait;	1744	$_[0]->_wait;
…		…
1084	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1746	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1085	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1747	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1086	}	1748	}
1087		1749
1088	sub cb {	1750	sub cb {
1089	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1751	my $cv = shift;
		1752
		1753	@_
		1754	and $cv->{_ae_cb} = shift
		1755	and $cv->{_ae_sent}
		1756	and (delete $cv->{_ae_cb})->($cv);
		1757
1090	$_[0]{_ae_cb}	1758	$cv->{_ae_cb}
1091	}	1759	}
1092		1760
1093	sub begin {	1761	sub begin {
1094	++$_[0]{_ae_counter};	1762	++$_[0]{_ae_counter};
1095	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1763	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1101	}	1769	}
1102		1770
1103	# undocumented/compatibility with pre-3.4	1771	# undocumented/compatibility with pre-3.4
1104	*broadcast = \&send;	1772	*broadcast = \&send;
1105	*wait = \&_wait;	1773	*wait = \&_wait;
		1774
		1775	=head1 ERROR AND EXCEPTION HANDLING
		1776
		1777	In general, AnyEvent does not do any error handling - it relies on the
		1778	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1779	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1780	checking of all AnyEvent methods, however, which is highly useful during
		1781	development.
		1782
		1783	As for exception handling (i.e. runtime errors and exceptions thrown while
		1784	executing a callback), this is not only highly event-loop specific, but
		1785	also not in any way wrapped by this module, as this is the job of the main
		1786	program.
		1787
		1788	The pure perl event loop simply re-throws the exception (usually
		1789	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1790	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1791	so on.
		1792
		1793	=head1 ENVIRONMENT VARIABLES
		1794
		1795	The following environment variables are used by this module or its
		1796	submodules.
		1797
		1798	Note that AnyEvent will remove I<all> environment variables starting with
		1799	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1800	enabled.
		1801
		1802	=over 4
		1803
		1804	=item C<PERL_ANYEVENT_VERBOSE>
		1805
		1806	By default, AnyEvent will be completely silent except in fatal
		1807	conditions. You can set this environment variable to make AnyEvent more
		1808	talkative.
		1809
		1810	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1811	conditions, such as not being able to load the event model specified by
		1812	C<PERL_ANYEVENT_MODEL>.
		1813
		1814	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1815	model it chooses.
		1816
		1817	When set to C<8> or higher, then AnyEvent will report extra information on
		1818	which optional modules it loads and how it implements certain features.
		1819
		1820	=item C<PERL_ANYEVENT_STRICT>
		1821
		1822	AnyEvent does not do much argument checking by default, as thorough
		1823	argument checking is very costly. Setting this variable to a true value
		1824	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1825	check the arguments passed to most method calls. If it finds any problems,
		1826	it will croak.
		1827
		1828	In other words, enables "strict" mode.
		1829
		1830	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1831	>>, it is definitely recommended to keep it off in production. Keeping
		1832	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1833	can be very useful, however.
		1834
		1835	=item C<PERL_ANYEVENT_MODEL>
		1836
		1837	This can be used to specify the event model to be used by AnyEvent, before
		1838	auto detection and -probing kicks in. It must be a string consisting
		1839	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1840	and the resulting module name is loaded and if the load was successful,
		1841	used as event model. If it fails to load AnyEvent will proceed with
		1842	auto detection and -probing.
		1843
		1844	This functionality might change in future versions.
		1845
		1846	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1847	could start your program like this:
		1848
		1849	PERL_ANYEVENT_MODEL=Perl perl ...
		1850
		1851	=item C<PERL_ANYEVENT_PROTOCOLS>
		1852
		1853	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1854	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1855	of auto probing).
		1856
		1857	Must be set to a comma-separated list of protocols or address families,
		1858	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1859	used, and preference will be given to protocols mentioned earlier in the
		1860	list.
		1861
		1862	This variable can effectively be used for denial-of-service attacks
		1863	against local programs (e.g. when setuid), although the impact is likely
		1864	small, as the program has to handle conenction and other failures anyways.
		1865
		1866	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1867	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1868	- only support IPv4, never try to resolve or contact IPv6
		1869	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1870	IPv6, but prefer IPv6 over IPv4.
		1871
		1872	=item C<PERL_ANYEVENT_EDNS0>
		1873
		1874	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1875	for DNS. This extension is generally useful to reduce DNS traffic, but
		1876	some (broken) firewalls drop such DNS packets, which is why it is off by
		1877	default.
		1878
		1879	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1880	EDNS0 in its DNS requests.
		1881
		1882	=item C<PERL_ANYEVENT_MAX_FORKS>
		1883
		1884	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1885	will create in parallel.
		1886
		1887	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1888
		1889	The default value for the C<max_outstanding> parameter for the default DNS
		1890	resolver - this is the maximum number of parallel DNS requests that are
		1891	sent to the DNS server.
		1892
		1893	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1894
		1895	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1896	configuration) in the default resolver. When set to the empty string, no
		1897	default config will be used.
		1898
		1899	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1900
		1901	When neither C<ca_file> nor C<ca_path> was specified during
		1902	L<AnyEvent::TLS> context creation, and either of these environment
		1903	variables exist, they will be used to specify CA certificate locations
		1904	instead of a system-dependent default.
		1905
		1906	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1907
		1908	When these are set to C<1>, then the respective modules are not
		1909	loaded. Mostly good for testing AnyEvent itself.
		1910
		1911	=back
1106		1912
1107	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1913	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1108		1914
1109	This is an advanced topic that you do not normally need to use AnyEvent in	1915	This is an advanced topic that you do not normally need to use AnyEvent in
1110	a module. This section is only of use to event loop authors who want to	1916	a module. This section is only of use to event loop authors who want to
…		…
1144		1950
1145	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1951	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1146	condition variables: code blocking while waiting for a condition will	1952	condition variables: code blocking while waiting for a condition will
1147	C<die>. This still works with most modules/usages, and blocking calls must	1953	C<die>. This still works with most modules/usages, and blocking calls must
1148	not be done in an interactive application, so it makes sense.	1954	not be done in an interactive application, so it makes sense.
1149
1150	=head1 ENVIRONMENT VARIABLES
1151
1152	The following environment variables are used by this module:
1153
1154	=over 4
1155
1156	=item C<PERL_ANYEVENT_VERBOSE>
1157
1158	By default, AnyEvent will be completely silent except in fatal
1159	conditions. You can set this environment variable to make AnyEvent more
1160	talkative.
1161
1162	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1163	conditions, such as not being able to load the event model specified by
1164	C<PERL_ANYEVENT_MODEL>.
1165
1166	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1167	model it chooses.
1168
1169	=item C<PERL_ANYEVENT_MODEL>
1170
1171	This can be used to specify the event model to be used by AnyEvent, before
1172	auto detection and -probing kicks in. It must be a string consisting
1173	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1174	and the resulting module name is loaded and if the load was successful,
1175	used as event model. If it fails to load AnyEvent will proceed with
1176	auto detection and -probing.
1177
1178	This functionality might change in future versions.
1179
1180	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1181	could start your program like this:
1182
1183	PERL_ANYEVENT_MODEL=Perl perl ...
1184
1185	=item C<PERL_ANYEVENT_PROTOCOLS>
1186
1187	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1188	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1189	of auto probing).
1190
1191	Must be set to a comma-separated list of protocols or address families,
1192	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1193	used, and preference will be given to protocols mentioned earlier in the
1194	list.
1195
1196	This variable can effectively be used for denial-of-service attacks
1197	against local programs (e.g. when setuid), although the impact is likely
1198	small, as the program has to handle connection errors already-
1199
1200	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1201	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1202	- only support IPv4, never try to resolve or contact IPv6
1203	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1204	IPv6, but prefer IPv6 over IPv4.
1205
1206	=item C<PERL_ANYEVENT_EDNS0>
1207
1208	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1209	for DNS. This extension is generally useful to reduce DNS traffic, but
1210	some (broken) firewalls drop such DNS packets, which is why it is off by
1211	default.
1212
1213	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1214	EDNS0 in its DNS requests.
1215
1216	=item C<PERL_ANYEVENT_MAX_FORKS>
1217
1218	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1219	will create in parallel.
1220
1221	=back
1222		1955
1223	=head1 EXAMPLE PROGRAM	1956	=head1 EXAMPLE PROGRAM
1224		1957
1225	The following program uses an I/O watcher to read data from STDIN, a timer	1958	The following program uses an I/O watcher to read data from STDIN, a timer
1226	to display a message once per second, and a condition variable to quit the	1959	to display a message once per second, and a condition variable to quit the
…		…
1239	warn "read: $input\n"; # output what has been read	1972	warn "read: $input\n"; # output what has been read
1240	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1973	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1241	},	1974	},
1242	);	1975	);
1243		1976
1244	my $time_watcher; # can only be used once
1245
1246	sub new_timer {
1247	$timer = AnyEvent->timer (after => 1, cb => sub {	1977	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1248	warn "timeout\n"; # print 'timeout' about every second	1978	warn "timeout\n"; # print 'timeout' at most every second
1249	&new_timer; # and restart the time
1250	});	1979	});
1251	}
1252
1253	new_timer; # create first timer
1254		1980
1255	$cv->recv; # wait until user enters /^q/i	1981	$cv->recv; # wait until user enters /^q/i
1256		1982
1257	=head1 REAL-WORLD EXAMPLE	1983	=head1 REAL-WORLD EXAMPLE
1258		1984
…		…
1389	through AnyEvent. The benchmark creates a lot of timers (with a zero	2115	through AnyEvent. The benchmark creates a lot of timers (with a zero
1390	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2116	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1391	which it is), lets them fire exactly once and destroys them again.	2117	which it is), lets them fire exactly once and destroys them again.
1392		2118
1393	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2119	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1394	distribution.	2120	distribution. It uses the L<AE> interface, which makes a real difference
		2121	for the EV and Perl backends only.
1395		2122
1396	=head3 Explanation of the columns	2123	=head3 Explanation of the columns
1397		2124
1398	I<watcher> is the number of event watchers created/destroyed. Since	2125	I<watcher> is the number of event watchers created/destroyed. Since
1399	different event models feature vastly different performances, each event	2126	different event models feature vastly different performances, each event
…		…
1420	watcher.	2147	watcher.
1421		2148
1422	=head3 Results	2149	=head3 Results
1423		2150
1424	name watchers bytes create invoke destroy comment	2151	name watchers bytes create invoke destroy comment
1425	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2152	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1426	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2153	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1427	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2154	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1428	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2155	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1429	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2156	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1430	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2157	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2158	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2159	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1431	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2160	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1432	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2161	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1433	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2162	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1434	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2163	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1435		2164
1436	=head3 Discussion	2165	=head3 Discussion
1437		2166
1438	The benchmark does I<not> measure scalability of the event loop very	2167	The benchmark does I<not> measure scalability of the event loop very
1439	well. For example, a select-based event loop (such as the pure perl one)	2168	well. For example, a select-based event loop (such as the pure perl one)
…		…
1451	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2180	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1452	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2181	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1453	cycles with POE.	2182	cycles with POE.
1454		2183
1455	C<EV> is the sole leader regarding speed and memory use, which are both	2184	C<EV> is the sole leader regarding speed and memory use, which are both
1456	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2185	maximal/minimal, respectively. When using the L<AE> API there is zero
		2186	overhead (when going through the AnyEvent API create is about 5-6 times
		2187	slower, with other times being equal, so still uses far less memory than
1457	far less memory than any other event loop and is still faster than Event	2188	any other event loop and is still faster than Event natively).
1458	natively.
1459		2189
1460	The pure perl implementation is hit in a few sweet spots (both the	2190	The pure perl implementation is hit in a few sweet spots (both the
1461	constant timeout and the use of a single fd hit optimisations in the perl	2191	constant timeout and the use of a single fd hit optimisations in the perl
1462	interpreter and the backend itself). Nevertheless this shows that it	2192	interpreter and the backend itself). Nevertheless this shows that it
1463	adds very little overhead in itself. Like any select-based backend its	2193	adds very little overhead in itself. Like any select-based backend its
1464	performance becomes really bad with lots of file descriptors (and few of	2194	performance becomes really bad with lots of file descriptors (and few of
1465	them active), of course, but this was not subject of this benchmark.	2195	them active), of course, but this was not subject of this benchmark.
1466		2196
1467	The C<Event> module has a relatively high setup and callback invocation	2197	The C<Event> module has a relatively high setup and callback invocation
1468	cost, but overall scores in on the third place.	2198	cost, but overall scores in on the third place.
		2199
		2200	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2201	when using its pure perl backend.
1469		2202
1470	C<Glib>'s memory usage is quite a bit higher, but it features a	2203	C<Glib>'s memory usage is quite a bit higher, but it features a
1471	faster callback invocation and overall ends up in the same class as	2204	faster callback invocation and overall ends up in the same class as
1472	C<Event>. However, Glib scales extremely badly, doubling the number of	2205	C<Event>. However, Glib scales extremely badly, doubling the number of
1473	watchers increases the processing time by more than a factor of four,	2206	watchers increases the processing time by more than a factor of four,
…		…
1534	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2267	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1535	(1%) are active. This mirrors the activity of large servers with many	2268	(1%) are active. This mirrors the activity of large servers with many
1536	connections, most of which are idle at any one point in time.	2269	connections, most of which are idle at any one point in time.
1537		2270
1538	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2271	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1539	distribution.	2272	distribution. It uses the L<AE> interface, which makes a real difference
		2273	for the EV and Perl backends only.
1540		2274
1541	=head3 Explanation of the columns	2275	=head3 Explanation of the columns
1542		2276
1543	I<sockets> is the number of sockets, and twice the number of "servers" (as	2277	I<sockets> is the number of sockets, and twice the number of "servers" (as
1544	each server has a read and write socket end).	2278	each server has a read and write socket end).
…		…
1551	it to another server. This includes deleting the old timeout and creating	2285	it to another server. This includes deleting the old timeout and creating
1552	a new one that moves the timeout into the future.	2286	a new one that moves the timeout into the future.
1553		2287
1554	=head3 Results	2288	=head3 Results
1555		2289
1556	name sockets create request	2290	name sockets create request
1557	EV 20000 69.01 11.16	2291	EV 20000 62.66 7.99
1558	Perl 20000 73.32 35.87	2292	Perl 20000 68.32 32.64
1559	Event 20000 212.62 257.32	2293	IOAsync 20000 174.06 101.15 epoll
1560	Glib 20000 651.16 1896.30	2294	IOAsync 20000 174.67 610.84 poll
		2295	Event 20000 202.69 242.91
		2296	Glib 20000 557.01 1689.52
1561	POE 20000 349.67 12317.24 uses POE::Loop::Event	2297	POE 20000 341.54 12086.32 uses POE::Loop::Event
1562		2298
1563	=head3 Discussion	2299	=head3 Discussion
1564		2300
1565	This benchmark I<does> measure scalability and overall performance of the	2301	This benchmark I<does> measure scalability and overall performance of the
1566	particular event loop.	2302	particular event loop.
…		…
1568	EV is again fastest. Since it is using epoll on my system, the setup time	2304	EV is again fastest. Since it is using epoll on my system, the setup time
1569	is relatively high, though.	2305	is relatively high, though.
1570		2306
1571	Perl surprisingly comes second. It is much faster than the C-based event	2307	Perl surprisingly comes second. It is much faster than the C-based event
1572	loops Event and Glib.	2308	loops Event and Glib.
		2309
		2310	IO::Async performs very well when using its epoll backend, and still quite
		2311	good compared to Glib when using its pure perl backend.
1573		2312
1574	Event suffers from high setup time as well (look at its code and you will	2313	Event suffers from high setup time as well (look at its code and you will
1575	understand why). Callback invocation also has a high overhead compared to	2314	understand why). Callback invocation also has a high overhead compared to
1576	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2315	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1577	uses select or poll in basically all documented configurations.	2316	uses select or poll in basically all documented configurations.
…		…
1640	=item * C-based event loops perform very well with small number of	2379	=item * C-based event loops perform very well with small number of
1641	watchers, as the management overhead dominates.	2380	watchers, as the management overhead dominates.
1642		2381
1643	=back	2382	=back
1644		2383
		2384	=head2 THE IO::Lambda BENCHMARK
		2385
		2386	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2387	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2388	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2389	shouldn't come as a surprise to anybody). As such, the benchmark is
		2390	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2391	very optimal. But how would AnyEvent compare when used without the extra
		2392	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2393
		2394	The benchmark itself creates an echo-server, and then, for 500 times,
		2395	connects to the echo server, sends a line, waits for the reply, and then
		2396	creates the next connection. This is a rather bad benchmark, as it doesn't
		2397	test the efficiency of the framework or much non-blocking I/O, but it is a
		2398	benchmark nevertheless.
		2399
		2400	name runtime
		2401	Lambda/select 0.330 sec
		2402	+ optimized 0.122 sec
		2403	Lambda/AnyEvent 0.327 sec
		2404	+ optimized 0.138 sec
		2405	Raw sockets/select 0.077 sec
		2406	POE/select, components 0.662 sec
		2407	POE/select, raw sockets 0.226 sec
		2408	POE/select, optimized 0.404 sec
		2409
		2410	AnyEvent/select/nb 0.085 sec
		2411	AnyEvent/EV/nb 0.068 sec
		2412	+state machine 0.134 sec
		2413
		2414	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2415	benchmarks actually make blocking connects and use 100% blocking I/O,
		2416	defeating the purpose of an event-based solution. All of the newly
		2417	written AnyEvent benchmarks use 100% non-blocking connects (using
		2418	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2419	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2420	generally require a lot more bookkeeping and event handling than blocking
		2421	connects (which involve a single syscall only).
		2422
		2423	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2424	offers similar expressive power as POE and IO::Lambda, using conventional
		2425	Perl syntax. This means that both the echo server and the client are 100%
		2426	non-blocking, further placing it at a disadvantage.
		2427
		2428	As you can see, the AnyEvent + EV combination even beats the
		2429	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2430	backend easily beats IO::Lambda and POE.
		2431
		2432	And even the 100% non-blocking version written using the high-level (and
		2433	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2434	higher level ("unoptimised") abstractions by a large margin, even though
		2435	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2436
		2437	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2438	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2439	part of the IO::Lambda distribution and were used without any changes.
		2440
		2441
		2442	=head1 SIGNALS
		2443
		2444	AnyEvent currently installs handlers for these signals:
		2445
		2446	=over 4
		2447
		2448	=item SIGCHLD
		2449
		2450	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2451	emulation for event loops that do not support them natively. Also, some
		2452	event loops install a similar handler.
		2453
		2454	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2455	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2456
		2457	=item SIGPIPE
		2458
		2459	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2460	when AnyEvent gets loaded.
		2461
		2462	The rationale for this is that AnyEvent users usually do not really depend
		2463	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2464	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2465	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2466	some random socket.
		2467
		2468	The rationale for installing a no-op handler as opposed to ignoring it is
		2469	that this way, the handler will be restored to defaults on exec.
		2470
		2471	Feel free to install your own handler, or reset it to defaults.
		2472
		2473	=back
		2474
		2475	=cut
		2476
		2477	undef $SIG{CHLD}
		2478	if $SIG{CHLD} eq 'IGNORE';
		2479
		2480	$SIG{PIPE} = sub { }
		2481	unless defined $SIG{PIPE};
		2482
		2483	=head1 RECOMMENDED/OPTIONAL MODULES
		2484
		2485	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2486	it's built-in modules) are required to use it.
		2487
		2488	That does not mean that AnyEvent won't take advantage of some additional
		2489	modules if they are installed.
		2490
		2491	This section explains which additional modules will be used, and how they
		2492	affect AnyEvent's operation.
		2493
		2494	=over 4
		2495
		2496	=item L<Async::Interrupt>
		2497
		2498	This slightly arcane module is used to implement fast signal handling: To
		2499	my knowledge, there is no way to do completely race-free and quick
		2500	signal handling in pure perl. To ensure that signals still get
		2501	delivered, AnyEvent will start an interval timer to wake up perl (and
		2502	catch the signals) with some delay (default is 10 seconds, look for
		2503	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2504
		2505	If this module is available, then it will be used to implement signal
		2506	catching, which means that signals will not be delayed, and the event loop
		2507	will not be interrupted regularly, which is more efficient (and good for
		2508	battery life on laptops).
		2509
		2510	This affects not just the pure-perl event loop, but also other event loops
		2511	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2512
		2513	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2514	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2515	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2516	does nothing for those backends.
		2517
		2518	=item L<EV>
		2519
		2520	This module isn't really "optional", as it is simply one of the backend
		2521	event loops that AnyEvent can use. However, it is simply the best event
		2522	loop available in terms of features, speed and stability: It supports
		2523	the AnyEvent API optimally, implements all the watcher types in XS, does
		2524	automatic timer adjustments even when no monotonic clock is available,
		2525	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2526	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2527	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2528
		2529	=item L<Guard>
		2530
		2531	The guard module, when used, will be used to implement
		2532	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2533	lot less memory), but otherwise doesn't affect guard operation much. It is
		2534	purely used for performance.
		2535
		2536	=item L<JSON> and L<JSON::XS>
		2537
		2538	One of these modules is required when you want to read or write JSON data
		2539	via L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2540	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2541
		2542	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2543	installed.
		2544
		2545	=item L<Net::SSLeay>
		2546
		2547	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2548	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2549	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2550
		2551	=item L<Time::HiRes>
		2552
		2553	This module is part of perl since release 5.008. It will be used when the
		2554	chosen event library does not come with a timing source on it's own. The
		2555	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2556	try to use a monotonic clock for timing stability.
		2557
		2558	=back
		2559
1645		2560
1646	=head1 FORK	2561	=head1 FORK
1647		2562
1648	Most event libraries are not fork-safe. The ones who are usually are	2563	Most event libraries are not fork-safe. The ones who are usually are
1649	because they rely on inefficient but fork-safe C<select> or C<poll>	2564	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1650	calls. Only L<EV> is fully fork-aware.	2565	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2566	are usually badly thought-out hacks that are incompatible with fork in
		2567	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2568	continue event-processing in both parent and child (or both, if you know
		2569	what you are doing).
		2570
		2571	This means that, in general, you cannot fork and do event processing in
		2572	the child if the event library was initialised before the fork (which
		2573	usually happens when the first AnyEvent watcher is created, or the library
		2574	is loaded).
1651		2575
1652	If you have to fork, you must either do so I<before> creating your first	2576	If you have to fork, you must either do so I<before> creating your first
1653	watcher OR you must not use AnyEvent at all in the child.	2577	watcher OR you must not use AnyEvent at all in the child OR you must do
		2578	something completely out of the scope of AnyEvent.
		2579
		2580	The problem of doing event processing in the parent I<and> the child
		2581	is much more complicated: even for backends that I<are> fork-aware or
		2582	fork-safe, their behaviour is not usually what you want: fork clones all
		2583	watchers, that means all timers, I/O watchers etc. are active in both
		2584	parent and child, which is almost never what you want. USing C<exec>
		2585	to start worker children from some kind of manage rprocess is usually
		2586	preferred, because it is much easier and cleaner, at the expense of having
		2587	to have another binary.
1654		2588
1655		2589
1656	=head1 SECURITY CONSIDERATIONS	2590	=head1 SECURITY CONSIDERATIONS
1657		2591
1658	AnyEvent can be forced to load any event model via	2592	AnyEvent can be forced to load any event model via
…		…
1669		2603
1670	use AnyEvent;	2604	use AnyEvent;
1671		2605
1672	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2606	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1673	be used to probe what backend is used and gain other information (which is	2607	be used to probe what backend is used and gain other information (which is
1674	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2608	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2609	$ENV{PERL_ANYEVENT_STRICT}.
		2610
		2611	Note that AnyEvent will remove I<all> environment variables starting with
		2612	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2613	enabled.
		2614
		2615
		2616	=head1 BUGS
		2617
		2618	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2619	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2620	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2621	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2622	pronounced).
1675		2623
1676		2624
1677	=head1 SEE ALSO	2625	=head1 SEE ALSO
1678		2626
1679	Utility functions: L<AnyEvent::Util>.	2627	Utility functions: L<AnyEvent::Util>.
…		…
1682	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2630	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1683		2631
1684	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2632	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1685	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2633	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1686	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2634	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1687	L<AnyEvent::Impl::POE>.	2635	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1688		2636
1689	Non-blocking file handles, sockets, TCP clients and	2637	Non-blocking file handles, sockets, TCP clients and
1690	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2638	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1691		2639
1692	Asynchronous DNS: L<AnyEvent::DNS>.	2640	Asynchronous DNS: L<AnyEvent::DNS>.
1693		2641
1694	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2642	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2643	L<Coro::Event>,
1695		2644
1696	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2645	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2646	L<AnyEvent::HTTP>.
1697		2647
1698		2648
1699	=head1 AUTHOR	2649	=head1 AUTHOR
1700		2650
1701	Marc Lehmann <schmorp@schmorp.de>	2651	Marc Lehmann <schmorp@schmorp.de>

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