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Revision 1.151 by root, Sat May 31 13:38:01 2008 UTC vs.
Revision 1.302 by root, Fri Dec 4 16:31:57 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
28		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
33		58
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
36		61
37	First and foremost, I<AnyEvent is not an event model> itself, it only	62	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	63	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	65	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	66	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
43		69
44	The goal of AnyEvent is to offer module authors the ability to do event	70	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	71	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
48	model you use.	74	model you use.
49		75
50	For modules like POE or IO::Async (which is a total misnomer as it is	76	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	77	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	78	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	80	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	81	module are I<also> forced to use the same event loop you use.
56		82
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	85	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	86	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	87	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	88	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	89	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
65		91
66	In addition to being free of having to use I<the one and only true event	92	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	93	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	94	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	95	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
129	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
130	is in control).	156	is in control).
131		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
132	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
133	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	166	to it).
135		167
136	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
149	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
150	declared.	182	declared.
151		183
152	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
153		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	192	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
156		194
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	195	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		196	for events (AnyEvent might or might not keep a reference to this file
		197	handle). Note that only file handles pointing to things for which
		198	non-blocking operation makes sense are allowed. This includes sockets,
		199	most character devices, pipes, fifos and so on, but not for example files
		200	or block devices.
		201
158	for events. C<poll> must be a string that is either C<r> or C<w>,	202	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
160	respectively. C<cb> is the callback to invoke each time the file handle	205	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		206
163	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
166		210
…		…
170		214
171	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	216	always use non-blocking calls when reading/writing from/to your file
173	handles.	217	handles.
174		218
175	Example:
176
177	# wait for readability of STDIN, then read a line and disable the watcher	219	Example: wait for readability of STDIN, then read a line and disable the
		220	watcher.
		221
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	224	warn "read: $input\n";
181	undef $w;	225	undef $w;
182	});	226	});
183		227
184	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
185		229
		230	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		231
		232	$w = AnyEvent->timer (
		233	after => <fractional_seconds>,
		234	interval => <fractional_seconds>,
		235	cb => <callback>,
		236	);
		237
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	238	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	239	method with the following mandatory arguments:
188		240
189	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	242	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		244
193	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
196		248
197	The timer callback will be invoked at most once: if you want a repeating	249	The callback will normally be invoked once only. If you specify another
198	timer you have to create a new watcher (this is a limitation by both Tk	250	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	251	callback will be invoked regularly at that interval (in fractional
		252	seconds) after the first invocation. If C<interval> is specified with a
		253	false value, then it is treated as if it were missing.
200		254
201	Example:	255	The callback will be rescheduled before invoking the callback, but no
		256	attempt is done to avoid timer drift in most backends, so the interval is
		257	only approximate.
202		258
203	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	262	warn "timeout\n";
206	});	263	});
207		264
208	# to cancel the timer:	265	# to cancel the timer:
209	undef $w;	266	undef $w;
210		267
211	Example 2:
212
213	# fire an event after 0.5 seconds, then roughly every second	268	Example 2: fire an event after 0.5 seconds, then roughly every second.
214	my $w;
215		269
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
219	};	272	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		273
224	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
225		275
226	There are two ways to handle timers: based on real time (relative, "fire	276	There are two ways to handle timers: based on real time (relative, "fire
227	in 10 seconds") and based on wallclock time (absolute, "fire at 12	277	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
300	In either case, if you care (and in most cases, you don't), then you	350	In either case, if you care (and in most cases, you don't), then you
301	can get whatever behaviour you want with any event loop, by taking the	351	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	353	account.
304		354
		355	=item AnyEvent->now_update
		356
		357	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		358	the current time for each loop iteration (see the discussion of L<<
		359	AnyEvent->now >>, above).
		360
		361	When a callback runs for a long time (or when the process sleeps), then
		362	this "current" time will differ substantially from the real time, which
		363	might affect timers and time-outs.
		364
		365	When this is the case, you can call this method, which will update the
		366	event loop's idea of "current time".
		367
		368	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	Sometimes there is a need to do something, but it is not so important
		509	to do it instantly, but only when there is nothing better to do. This
		510	"nothing better to do" is usually defined to be "no other events need
		511	attention by the event loop".
		512
		513	Idle watchers ideally get invoked when the event loop has nothing
		514	better to do, just before it would block the process to wait for new
		515	events. Instead of blocking, the idle watcher is invoked.
		516
		517	Most event loops unfortunately do not really support idle watchers (only
		518	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		519	will simply call the callback "from time to time".
		520
		521	Example: read lines from STDIN, but only process them when the
		522	program is otherwise idle:
		523
		524	my @lines; # read data
		525	my $idle_w;
		526	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		527	push @lines, scalar <STDIN>;
		528
		529	# start an idle watcher, if not already done
		530	$idle_w ||= AnyEvent->idle (cb => sub {
		531	# handle only one line, when there are lines left
		532	if (my $line = shift @lines) {
		533	print "handled when idle: $line";
		534	} else {
		535	# otherwise disable the idle watcher again
		536	undef $idle_w;
		537	}
		538	});
		539	});
		540
373	=head2 CONDITION VARIABLES	541	=head2 CONDITION VARIABLES
		542
		543	$cv = AnyEvent->condvar;
		544
		545	$cv->send (<list>);
		546	my @res = $cv->recv;
374		547
375	If you are familiar with some event loops you will know that all of them	548	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	549	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	550	will actively watch for new events and call your callbacks.
378		551
379	AnyEvent is different, it expects somebody else to run the event loop and	552	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	553	loop and will only block when necessary (usually when told by the user).
381		554
382	The instrument to do that is called a "condition variable", so called	555	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	556	because they represent a condition that must become true.
		557
		558	Now is probably a good time to look at the examples further below.
384		559
385	Condition variables can be created by calling the C<< AnyEvent->condvar	560	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	561	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	562	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	563	becomes true, with the condition variable as the first argument (but not
		564	the results).
389		565
390	After creation, the condition variable is "false" until it becomes "true"	566	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	567	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<<	568	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	569	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	571	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	572	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	573	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	574	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	575	used to represent a transaction, which finishes at some point and delivers
400	a result.	576	a result. And yet some people know them as "futures" - a promise to
		577	compute/deliver something that you can wait for.
401		578
402	Condition variables are very useful to signal that something has finished,	579	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	580	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	581	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	582	availability of results. The user can either act when the callback is
…		…
439	after => 1,	616	after => 1,
440	cb => sub { $result_ready->send },	617	cb => sub { $result_ready->send },
441	);	618	);
442		619
443	# this "blocks" (while handling events) till the callback	620	# this "blocks" (while handling events) till the callback
444	# calls send	621	# calls ->send
445	$result_ready->recv;	622	$result_ready->recv;
446		623
447	Example: wait for a timer, but take advantage of the fact that	624	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	625	variables are also callable directly.
449		626
450	my $done = AnyEvent->condvar;	627	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	628	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	629	$done->recv;
		630
		631	Example: Imagine an API that returns a condvar and doesn't support
		632	callbacks. This is how you make a synchronous call, for example from
		633	the main program:
		634
		635	use AnyEvent::CouchDB;
		636
		637	...
		638
		639	my @info = $couchdb->info->recv;
		640
		641	And this is how you would just set a callback to be called whenever the
		642	results are available:
		643
		644	$couchdb->info->cb (sub {
		645	my @info = $_[0]->recv;
		646	});
453		647
454	=head3 METHODS FOR PRODUCERS	648	=head3 METHODS FOR PRODUCERS
455		649
456	These methods should only be used by the producing side, i.e. the	650	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	651	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	664	immediately from within send.
471		665
472	Any arguments passed to the C<send> call will be returned by all	666	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	667	future C<< ->recv >> calls.
474		668
475	Condition variables are overloaded so one can call them directly	669	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	670	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	671	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		672
484	=item $cv->croak ($error)	673	=item $cv->croak ($error)
485		674
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	675	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	676	C<Carp::croak> with the given error message/object/scalar.
488		677
489	This can be used to signal any errors to the condition variable	678	This can be used to signal any errors to the condition variable
490	user/consumer.	679	user/consumer. Doing it this way instead of calling C<croak> directly
		680	delays the error detetcion, but has the overwhelmign advantage that it
		681	diagnoses the error at the place where the result is expected, and not
		682	deep in some event clalback without connection to the actual code causing
		683	the problem.
491		684
492	=item $cv->begin ([group callback])	685	=item $cv->begin ([group callback])
493		686
494	=item $cv->end	687	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		688
498	These two methods can be used to combine many transactions/events into	689	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	690	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	691	to use a condition variable for the whole process.
501		692
502	Every call to C<< ->begin >> will increment a counter, and every call to	693	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	694	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	695	>>, 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	696	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.	697	>>, but that is not required. If no group callback was set, C<send> will
		698	be called without any arguments.
507		699
508	Let's clarify this with the ping example:	700	You can think of C<< $cv->send >> giving you an OR condition (one call
		701	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		702	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		703
		704	Let's start with a simple example: you have two I/O watchers (for example,
		705	STDOUT and STDERR for a program), and you want to wait for both streams to
		706	close before activating a condvar:
509		707
510	my $cv = AnyEvent->condvar;	708	my $cv = AnyEvent->condvar;
511		709
		710	$cv->begin; # first watcher
		711	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		712	defined sysread $fh1, my $buf, 4096
		713	or $cv->end;
		714	});
		715
		716	$cv->begin; # second watcher
		717	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		718	defined sysread $fh2, my $buf, 4096
		719	or $cv->end;
		720	});
		721
		722	$cv->recv;
		723
		724	This works because for every event source (EOF on file handle), there is
		725	one call to C<begin>, so the condvar waits for all calls to C<end> before
		726	sending.
		727
		728	The ping example mentioned above is slightly more complicated, as the
		729	there are results to be passwd back, and the number of tasks that are
		730	begung can potentially be zero:
		731
		732	my $cv = AnyEvent->condvar;
		733
512	my %result;	734	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	735	$cv->begin (sub { shift->send (\%result) });
514		736
515	for my $host (@list_of_hosts) {	737	for my $host (@list_of_hosts) {
516	$cv->begin;	738	$cv->begin;
517	ping_host_then_call_callback $host, sub {	739	ping_host_then_call_callback $host, sub {
518	$result{$host} = ...;	740	$result{$host} = ...;
…		…
533	loop, which serves two important purposes: first, it sets the callback	755	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	756	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	757	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	758	doesn't execute once).
537		759
538	This is the general pattern when you "fan out" into multiple subrequests:	760	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>	761	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	762	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>.	763	subrequest you start, call C<begin> and for each subrequest you finish,
		764	call C<end>.
542		765
543	=back	766	=back
544		767
545	=head3 METHODS FOR CONSUMERS	768	=head3 METHODS FOR CONSUMERS
546		769
…		…
562	function will call C<croak>.	785	function will call C<croak>.
563		786
564	In list context, all parameters passed to C<send> will be returned,	787	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	788	in scalar context only the first one will be returned.
566		789
		790	Note that doing a blocking wait in a callback is not supported by any
		791	event loop, that is, recursive invocation of a blocking C<< ->recv
		792	>> is not allowed, and the C<recv> call will C<croak> if such a
		793	condition is detected. This condition can be slightly loosened by using
		794	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		795	any thread that doesn't run the event loop itself.
		796
567	Not all event models support a blocking wait - some die in that case	797	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	798	(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	799	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	800	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	801	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	802	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	803	while still supporting blocking waits if the caller so desires).
574		804
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	805	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	806	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	807	time). This will work even when the event loop does not support blocking
589	waits otherwise.	808	waits otherwise.
590		809
591	=item $bool = $cv->ready	810	=item $bool = $cv->ready
592		811
593	Returns true when the condition is "true", i.e. whether C<send> or	812	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	813	C<croak> have been called.
595		814
596	=item $cb = $cv->cb ([new callback])	815	=item $cb = $cv->cb ($cb->($cv))
597		816
598	This is a mutator function that returns the callback set and optionally	817	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	818	replaces it before doing so.
600		819
601	The callback will be called when the condition becomes "true", i.e. when	820	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	821	"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	822	the only argument being the condition variable itself. Calling C<recv>
604	is guaranteed not to block.	823	inside the callback or at any later time is guaranteed not to block.
605		824
606	=back	825	=back
607		826
		827	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		828
		829	The available backend classes are (every class has its own manpage):
		830
		831	=over 4
		832
		833	=item Backends that are autoprobed when no other event loop can be found.
		834
		835	EV is the preferred backend when no other event loop seems to be in
		836	use. If EV is not installed, then AnyEvent will fall back to its own
		837	pure-perl implementation, which is available everywhere as it comes with
		838	AnyEvent itself.
		839
		840	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		841	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		842
		843	=item Backends that are transparently being picked up when they are used.
		844
		845	These will be used when they are currently loaded when the first watcher
		846	is created, in which case it is assumed that the application is using
		847	them. This means that AnyEvent will automatically pick the right backend
		848	when the main program loads an event module before anything starts to
		849	create watchers. Nothing special needs to be done by the main program.
		850
		851	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		852	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		853	AnyEvent::Impl::Tk based on Tk, very broken.
		854	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		855	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		856	AnyEvent::Impl::Irssi used when running within irssi.
		857
		858	=item Backends with special needs.
		859
		860	Qt requires the Qt::Application to be instantiated first, but will
		861	otherwise be picked up automatically. As long as the main program
		862	instantiates the application before any AnyEvent watchers are created,
		863	everything should just work.
		864
		865	AnyEvent::Impl::Qt based on Qt.
		866
		867	Support for IO::Async can only be partial, as it is too broken and
		868	architecturally limited to even support the AnyEvent API. It also
		869	is the only event loop that needs the loop to be set explicitly, so
		870	it can only be used by a main program knowing about AnyEvent. See
		871	L<AnyEvent::Impl::Async> for the gory details.
		872
		873	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		874
		875	=item Event loops that are indirectly supported via other backends.
		876
		877	Some event loops can be supported via other modules:
		878
		879	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		880
		881	B<WxWidgets> has no support for watching file handles. However, you can
		882	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		883	polls 20 times per second, which was considered to be too horrible to even
		884	consider for AnyEvent.
		885
		886	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		887	backend, so it can be supported through POE.
		888
		889	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		890	load L<POE> when detecting them, in the hope that POE will pick them up,
		891	in which case everything will be automatic.
		892
		893	=back
		894
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	895	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		896
		897	These are not normally required to use AnyEvent, but can be useful to
		898	write AnyEvent extension modules.
		899
610	=over 4	900	=over 4
611		901
612	=item $AnyEvent::MODEL	902	=item $AnyEvent::MODEL
613		903
614	Contains C<undef> until the first watcher is being created. Then it	904	Contains C<undef> until the first watcher is being created, before the
		905	backend has been autodetected.
		906
615	contains the event model that is being used, which is the name of the	907	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	908	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	909	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	910	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		911	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		912
641	=item AnyEvent::detect	913	=item AnyEvent::detect
642		914
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	915	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	916	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	917	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	918	runtime, and not e.g. while initialising of your module.
		919
		920	If you need to do some initialisation before AnyEvent watchers are
		921	created, use C<post_detect>.
647		922
648	=item $guard = AnyEvent::post_detect { BLOCK }	923	=item $guard = AnyEvent::post_detect { BLOCK }
649		924
650	Arranges for the code block to be executed as soon as the event model is	925	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	926	autodetected (or immediately if this has already happened).
652		927
		928	The block will be executed I<after> the actual backend has been detected
		929	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		930	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		931	other initialisations - see the sources of L<AnyEvent::Strict> or
		932	L<AnyEvent::AIO> to see how this is used.
		933
		934	The most common usage is to create some global watchers, without forcing
		935	event module detection too early, for example, L<AnyEvent::AIO> creates
		936	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		937	avoid autodetecting the event module at load time.
		938
653	If called in scalar or list context, then it creates and returns an object	939	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	940	that automatically removes the callback again when it is destroyed (or
		941	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	942	a case where this is useful.
		943
		944	Example: Create a watcher for the IO::AIO module and store it in
		945	C<$WATCHER>. Only do so after the event loop is initialised, though.
		946
		947	our WATCHER;
		948
		949	my $guard = AnyEvent::post_detect {
		950	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		951	};
		952
		953	# the ||= is important in case post_detect immediately runs the block,
		954	# as to not clobber the newly-created watcher. assigning both watcher and
		955	# post_detect guard to the same variable has the advantage of users being
		956	# able to just C<undef $WATCHER> if the watcher causes them grief.
		957
		958	$WATCHER ||= $guard;
656		959
657	=item @AnyEvent::post_detect	960	=item @AnyEvent::post_detect
658		961
659	If there are any code references in this array (you can C<push> to it	962	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	963	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	964	the event loop has been chosen.
662		965
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	966	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,	967	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	968	array will be ignored.
666		969
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	970	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		971	it,as it takes care of these details.
		972
		973	This variable is mainly useful for modules that can do something useful
		974	when AnyEvent is used and thus want to know when it is initialised, but do
		975	not need to even load it by default. This array provides the means to hook
		976	into AnyEvent passively, without loading it.
668		977
669	=back	978	=back
670		979
671	=head1 WHAT TO DO IN A MODULE	980	=head1 WHAT TO DO IN A MODULE
672		981
…		…
727		1036
728		1037
729	=head1 OTHER MODULES	1038	=head1 OTHER MODULES
730		1039
731	The following is a non-exhaustive list of additional modules that use	1040	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1041	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	1042	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1043	come with AnyEvent, most are available via CPAN.
735		1044
736	=over 4	1045	=over 4
737		1046
738	=item L<AnyEvent::Util>	1047	=item L<AnyEvent::Util>
739		1048
740	Contains various utility functions that replace often-used but blocking	1049	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1050	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		1051
747	=item L<AnyEvent::Socket>	1052	=item L<AnyEvent::Socket>
748		1053
749	Provides various utility functions for (internet protocol) sockets,	1054	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1055	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1056	connections or tcp servers, with IPv6 and SRV record support and more.
752		1057
		1058	=item L<AnyEvent::Handle>
		1059
		1060	Provide read and write buffers, manages watchers for reads and writes,
		1061	supports raw and formatted I/O, I/O queued and fully transparent and
		1062	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1063
753	=item L<AnyEvent::DNS>	1064	=item L<AnyEvent::DNS>
754		1065
755	Provides rich asynchronous DNS resolver capabilities.	1066	Provides rich asynchronous DNS resolver capabilities.
756		1067
		1068	=item L<AnyEvent::HTTP>
		1069
		1070	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1071	HTTP requests.
		1072
757	=item L<AnyEvent::HTTPD>	1073	=item L<AnyEvent::HTTPD>
758		1074
759	Provides a simple web application server framework.	1075	Provides a simple web application server framework.
760		1076
761	=item L<AnyEvent::FastPing>	1077	=item L<AnyEvent::FastPing>
762		1078
763	The fastest ping in the west.	1079	The fastest ping in the west.
764		1080
		1081	=item L<AnyEvent::DBI>
		1082
		1083	Executes L<DBI> requests asynchronously in a proxy process.
		1084
		1085	=item L<AnyEvent::AIO>
		1086
		1087	Truly asynchronous I/O, should be in the toolbox of every event
		1088	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1089	together.
		1090
		1091	=item L<AnyEvent::BDB>
		1092
		1093	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1094	L<BDB> and AnyEvent together.
		1095
		1096	=item L<AnyEvent::GPSD>
		1097
		1098	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1099
765	=item L<Net::IRC3>	1100	=item L<AnyEvent::IRC>
766		1101
767	AnyEvent based IRC client module family.	1102	AnyEvent based IRC client module family (replacing the older Net::IRC3).
768		1103
769	=item L<Net::XMPP2>	1104	=item L<AnyEvent::XMPP>
770		1105
771	AnyEvent based XMPP (Jabber protocol) module family.	1106	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1107	Net::XMPP2>.
		1108
		1109	=item L<AnyEvent::IGS>
		1110
		1111	A non-blocking interface to the Internet Go Server protocol (used by
		1112	L<App::IGS>).
772		1113
773	=item L<Net::FCP>	1114	=item L<Net::FCP>
774		1115
775	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1116	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
776	of AnyEvent.	1117	of AnyEvent.
…		…
781		1122
782	=item L<Coro>	1123	=item L<Coro>
783		1124
784	Has special support for AnyEvent via L<Coro::AnyEvent>.	1125	Has special support for AnyEvent via L<Coro::AnyEvent>.
785		1126
786	=item L<AnyEvent::AIO>, L<IO::AIO>
787
788	Truly asynchronous I/O, should be in the toolbox of every event
789	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
790	together.
791
792	=item L<AnyEvent::BDB>, L<BDB>
793
794	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
795	IO::AIO and AnyEvent together.
796
797	=item L<IO::Lambda>
798
799	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
800
801	=back	1127	=back
802		1128
803	=cut	1129	=cut
804		1130
805	package AnyEvent;	1131	package AnyEvent;
806		1132
807	no warnings;	1133	# basically a tuned-down version of common::sense
808	use strict;	1134	sub common_sense {
		1135	# from common:.sense 1.0
		1136	${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
		1137	# use strict vars subs
		1138	$^H |= 0x00000600;
		1139	}
809		1140
		1141	BEGIN { AnyEvent::common_sense }
		1142
810	use Carp;	1143	use Carp ();
811		1144
812	our $VERSION = 4.11;	1145	our $VERSION = '5.21';
813	our $MODEL;	1146	our $MODEL;
814		1147
815	our $AUTOLOAD;	1148	our $AUTOLOAD;
816	our @ISA;	1149	our @ISA;
817		1150
818	our @REGISTRY;	1151	our @REGISTRY;
819		1152
820	our $WIN32;	1153	our $VERBOSE;
821		1154
822	BEGIN {	1155	BEGIN {
823	my $win32 = ! ! ($^O =~ /mswin32/i);	1156	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
824	eval "sub WIN32(){ $win32 }";	1157	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
825	}
826		1158
		1159	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1160	if ${^TAINT};
		1161
827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1162	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1163
		1164	}
		1165
		1166	our $MAX_SIGNAL_LATENCY = 10;
828		1167
829	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1168	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
830		1169
831	{	1170	{
832	my $idx;	1171	my $idx;
…		…
834	for reverse split /\s*,\s*/,	1173	for reverse split /\s*,\s*/,
835	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1174	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
836	}	1175	}
837		1176
838	my @models = (	1177	my @models = (
839	[EV:: => AnyEvent::Impl::EV::],	1178	[EV:: => AnyEvent::Impl::EV:: , 1],
840	[Event:: => AnyEvent::Impl::Event::],
841	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1179	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
842	# everything below here will not be autoprobed	1180	# everything below here will not (normally) be autoprobed
843	# as the pureperl backend should work everywhere	1181	# as the pureperl backend should work everywhere
844	# and is usually faster	1182	# and is usually faster
		1183	[Event:: => AnyEvent::Impl::Event::, 1],
		1184	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1185	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1186	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
845	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1187	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
846	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1188	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1189	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
850	[Wx:: => AnyEvent::Impl::POE::],	1190	[Wx:: => AnyEvent::Impl::POE::],
851	[Prima:: => AnyEvent::Impl::POE::],	1191	[Prima:: => AnyEvent::Impl::POE::],
		1192	# IO::Async is just too broken - we would need workarounds for its
		1193	# byzantine signal and broken child handling, among others.
		1194	# IO::Async is rather hard to detect, as it doesn't have any
		1195	# obvious default class.
		1196	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1197	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1198	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1199	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
852	);	1200	);
853		1201
854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1202	our %method = map +($_ => 1),
		1203	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
855		1204
856	our @post_detect;	1205	our @post_detect;
857		1206
858	sub post_detect(&) {	1207	sub post_detect(&) {
859	my ($cb) = @_;	1208	my ($cb) = @_;
860		1209
861	if ($MODEL) {	1210	if ($MODEL) {
862	$cb->();	1211	$cb->();
863		1212
864	1	1213	undef
865	} else {	1214	} else {
866	push @post_detect, $cb;	1215	push @post_detect, $cb;
867		1216
868	defined wantarray	1217	defined wantarray
869	? bless \$cb, "AnyEvent::Util::PostDetect"	1218	? bless \$cb, "AnyEvent::Util::postdetect"
870	: ()	1219	: ()
871	}	1220	}
872	}	1221	}
873		1222
874	sub AnyEvent::Util::PostDetect::DESTROY {	1223	sub AnyEvent::Util::postdetect::DESTROY {
875	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1224	@post_detect = grep $_ != ${$_[0]}, @post_detect;
876	}	1225	}
877		1226
878	sub detect() {	1227	sub detect() {
879	unless ($MODEL) {	1228	unless ($MODEL) {
880	no strict 'refs';
881	local $SIG{__DIE__};	1229	local $SIG{__DIE__};
882		1230
883	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1231	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
884	my $model = "AnyEvent::Impl::$1";	1232	my $model = "AnyEvent::Impl::$1";
885	if (eval "require $model") {	1233	if (eval "require $model") {
886	$MODEL = $model;	1234	$MODEL = $model;
887	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1235	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
888	} else {	1236	} else {
889	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1237	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
890	}	1238	}
891	}	1239	}
892		1240
893	# check for already loaded models	1241	# check for already loaded models
894	unless ($MODEL) {	1242	unless ($MODEL) {
895	for (@REGISTRY, @models) {	1243	for (@REGISTRY, @models) {
896	my ($package, $model) = @$_;	1244	my ($package, $model) = @$_;
897	if (${"$package\::VERSION"} > 0) {	1245	if (${"$package\::VERSION"} > 0) {
898	if (eval "require $model") {	1246	if (eval "require $model") {
899	$MODEL = $model;	1247	$MODEL = $model;
900	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1248	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
901	last;	1249	last;
902	}	1250	}
903	}	1251	}
904	}	1252	}
905		1253
906	unless ($MODEL) {	1254	unless ($MODEL) {
907	# try to load a model	1255	# try to autoload a model
908
909	for (@REGISTRY, @models) {	1256	for (@REGISTRY, @models) {
910	my ($package, $model) = @$_;	1257	my ($package, $model, $autoload) = @$_;
		1258	if (
		1259	$autoload
911	if (eval "require $package"	1260	and eval "require $package"
912	and ${"$package\::VERSION"} > 0	1261	and ${"$package\::VERSION"} > 0
913	and eval "require $model") {	1262	and eval "require $model"
		1263	) {
914	$MODEL = $model;	1264	$MODEL = $model;
915	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1265	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
916	last;	1266	last;
917	}	1267	}
918	}	1268	}
919		1269
920	$MODEL	1270	$MODEL
921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1271	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
922	}	1272	}
923	}	1273	}
924		1274
		1275	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1276
925	unshift @ISA, $MODEL;	1277	unshift @ISA, $MODEL;
926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1278
		1279	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927		1280
928	(shift @post_detect)->() while @post_detect;	1281	(shift @post_detect)->() while @post_detect;
929	}	1282	}
930		1283
931	$MODEL	1284	$MODEL
…		…
933		1286
934	sub AUTOLOAD {	1287	sub AUTOLOAD {
935	(my $func = $AUTOLOAD) =~ s/.*://;	1288	(my $func = $AUTOLOAD) =~ s/.*://;
936		1289
937	$method{$func}	1290	$method{$func}
938	or croak "$func: not a valid method for AnyEvent objects";	1291	or Carp::croak "$func: not a valid method for AnyEvent objects";
939		1292
940	detect unless $MODEL;	1293	detect unless $MODEL;
941		1294
942	my $class = shift;	1295	my $class = shift;
943	$class->$func (@_);	1296	$class->$func (@_);
944	}	1297	}
945		1298
		1299	# utility function to dup a filehandle. this is used by many backends
		1300	# to support binding more than one watcher per filehandle (they usually
		1301	# allow only one watcher per fd, so we dup it to get a different one).
		1302	sub _dupfh($$;$$) {
		1303	my ($poll, $fh, $r, $w) = @_;
		1304
		1305	# cygwin requires the fh mode to be matching, unix doesn't
		1306	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1307
		1308	open my $fh2, $mode, $fh
		1309	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1310
		1311	# we assume CLOEXEC is already set by perl in all important cases
		1312
		1313	($fh2, $rw)
		1314	}
		1315
		1316	=head1 SIMPLIFIED AE API
		1317
		1318	Starting with version 5.0, AnyEvent officially supports a second, much
		1319	simpler, API that is designed to reduce the calling, typing and memory
		1320	overhead.
		1321
		1322	See the L<AE> manpage for details.
		1323
		1324	=cut
		1325
		1326	package AE;
		1327
		1328	our $VERSION = $AnyEvent::VERSION;
		1329
		1330	sub io($$$) {
		1331	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1332	}
		1333
		1334	sub timer($$$) {
		1335	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1336	}
		1337
		1338	sub signal($$) {
		1339	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1340	}
		1341
		1342	sub child($$) {
		1343	AnyEvent->child (pid => $_[0], cb => $_[1])
		1344	}
		1345
		1346	sub idle($) {
		1347	AnyEvent->idle (cb => $_[0])
		1348	}
		1349
		1350	sub cv(;&) {
		1351	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1352	}
		1353
		1354	sub now() {
		1355	AnyEvent->now
		1356	}
		1357
		1358	sub now_update() {
		1359	AnyEvent->now_update
		1360	}
		1361
		1362	sub time() {
		1363	AnyEvent->time
		1364	}
		1365
946	package AnyEvent::Base;	1366	package AnyEvent::Base;
947		1367
948	# default implementation for now and time	1368	# default implementations for many methods
949		1369
950	use Time::HiRes ();	1370	sub _time() {
		1371	# probe for availability of Time::HiRes
		1372	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1373	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1374	*_time = \&Time::HiRes::time;
		1375	# if (eval "use POSIX (); (POSIX::times())...
		1376	} else {
		1377	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1378	*_time = sub { time }; # epic fail
		1379	}
951		1380
952	sub time { Time::HiRes::time }	1381	&_time
953	sub now { Time::HiRes::time }	1382	}
		1383
		1384	sub time { _time }
		1385	sub now { _time }
		1386	sub now_update { }
954		1387
955	# default implementation for ->condvar	1388	# default implementation for ->condvar
956		1389
957	sub condvar {	1390	sub condvar {
958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1391	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
959	}	1392	}
960		1393
961	# default implementation for ->signal	1394	# default implementation for ->signal
962		1395
963	our %SIG_CB;	1396	our $HAVE_ASYNC_INTERRUPT;
		1397
		1398	sub _have_async_interrupt() {
		1399	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1400	&& eval "use Async::Interrupt 1.02 (); 1")
		1401	unless defined $HAVE_ASYNC_INTERRUPT;
		1402
		1403	$HAVE_ASYNC_INTERRUPT
		1404	}
		1405
		1406	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1407	our (%SIG_ASY, %SIG_ASY_W);
		1408	our ($SIG_COUNT, $SIG_TW);
		1409
		1410	sub _signal_exec {
		1411	$HAVE_ASYNC_INTERRUPT
		1412	? $SIGPIPE_R->drain
		1413	: sysread $SIGPIPE_R, (my $dummy), 9;
		1414
		1415	while (%SIG_EV) {
		1416	for (keys %SIG_EV) {
		1417	delete $SIG_EV{$_};
		1418	$_->() for values %{ $SIG_CB{$_} || {} };
		1419	}
		1420	}
		1421	}
		1422
		1423	# install a dummy wakeup watcher to reduce signal catching latency
		1424	sub _sig_add() {
		1425	unless ($SIG_COUNT++) {
		1426	# try to align timer on a full-second boundary, if possible
		1427	my $NOW = AE::now;
		1428
		1429	$SIG_TW = AE::timer
		1430	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1431	$MAX_SIGNAL_LATENCY,
		1432	sub { } # just for the PERL_ASYNC_CHECK
		1433	;
		1434	}
		1435	}
		1436
		1437	sub _sig_del {
		1438	undef $SIG_TW
		1439	unless --$SIG_COUNT;
		1440	}
		1441
		1442	our $_sig_name_init; $_sig_name_init = sub {
		1443	eval q{ # poor man's autoloading
		1444	undef $_sig_name_init;
		1445
		1446	if (_have_async_interrupt) {
		1447	*sig2num = \&Async::Interrupt::sig2num;
		1448	*sig2name = \&Async::Interrupt::sig2name;
		1449	} else {
		1450	require Config;
		1451
		1452	my %signame2num;
		1453	@signame2num{ split ' ', $Config::Config{sig_name} }
		1454	= split ' ', $Config::Config{sig_num};
		1455
		1456	my @signum2name;
		1457	@signum2name[values %signame2num] = keys %signame2num;
		1458
		1459	*sig2num = sub($) {
		1460	$_[0] > 0 ? shift : $signame2num{+shift}
		1461	};
		1462	*sig2name = sub ($) {
		1463	$_[0] > 0 ? $signum2name[+shift] : shift
		1464	};
		1465	}
		1466	};
		1467	die if $@;
		1468	};
		1469
		1470	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1471	sub sig2name($) { &$_sig_name_init; &sig2name }
964		1472
965	sub signal {	1473	sub signal {
		1474	eval q{ # poor man's autoloading {}
		1475	# probe for availability of Async::Interrupt
		1476	if (_have_async_interrupt) {
		1477	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1478
		1479	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1480	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1481
		1482	} else {
		1483	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1484
		1485	require Fcntl;
		1486
		1487	if (AnyEvent::WIN32) {
		1488	require AnyEvent::Util;
		1489
		1490	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1491	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1492	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1493	} else {
		1494	pipe $SIGPIPE_R, $SIGPIPE_W;
		1495	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1496	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1497
		1498	# not strictly required, as $^F is normally 2, but let's make sure...
		1499	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1500	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1501	}
		1502
		1503	$SIGPIPE_R
		1504	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1505
		1506	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1507	}
		1508
		1509	*signal = sub {
966	my (undef, %arg) = @_;	1510	my (undef, %arg) = @_;
967		1511
968	my $signal = uc $arg{signal}	1512	my $signal = uc $arg{signal}
969	or Carp::croak "required option 'signal' is missing";	1513	or Carp::croak "required option 'signal' is missing";
970		1514
		1515	if ($HAVE_ASYNC_INTERRUPT) {
		1516	# async::interrupt
		1517
		1518	$signal = sig2num $signal;
971	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1519	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1520
		1521	$SIG_ASY{$signal} ||= new Async::Interrupt
		1522	cb => sub { undef $SIG_EV{$signal} },
		1523	signal => $signal,
		1524	pipe => [$SIGPIPE_R->filenos],
		1525	pipe_autodrain => 0,
		1526	;
		1527
		1528	} else {
		1529	# pure perl
		1530
		1531	# AE::Util has been loaded in signal
		1532	$signal = sig2name $signal;
		1533	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1534
972	$SIG{$signal} ||= sub {	1535	$SIG{$signal} ||= sub {
973	$_->() for values %{ $SIG_CB{$signal} || {} };	1536	local $!;
		1537	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1538	undef $SIG_EV{$signal};
		1539	};
		1540
		1541	# can't do signal processing without introducing races in pure perl,
		1542	# so limit the signal latency.
		1543	_sig_add;
		1544	}
		1545
		1546	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1547	};
		1548
		1549	*AnyEvent::Base::signal::DESTROY = sub {
		1550	my ($signal, $cb) = @{$_[0]};
		1551
		1552	_sig_del;
		1553
		1554	delete $SIG_CB{$signal}{$cb};
		1555
		1556	$HAVE_ASYNC_INTERRUPT
		1557	? delete $SIG_ASY{$signal}
		1558	: # delete doesn't work with older perls - they then
		1559	# print weird messages, or just unconditionally exit
		1560	# instead of getting the default action.
		1561	undef $SIG{$signal}
		1562	unless keys %{ $SIG_CB{$signal} };
		1563	};
974	};	1564	};
975		1565	die if $@;
976	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1566	&signal
977	}
978
979	sub AnyEvent::Base::Signal::DESTROY {
980	my ($signal, $cb) = @{$_[0]};
981
982	delete $SIG_CB{$signal}{$cb};
983
984	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
985	}	1567	}
986		1568
987	# default implementation for ->child	1569	# default implementation for ->child
988		1570
989	our %PID_CB;	1571	our %PID_CB;
990	our $CHLD_W;	1572	our $CHLD_W;
991	our $CHLD_DELAY_W;	1573	our $CHLD_DELAY_W;
992	our $PID_IDLE;
993	our $WNOHANG;	1574	our $WNOHANG;
994		1575
995	sub _child_wait {	1576	sub _emit_childstatus($$) {
996	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1577	my (undef, $rpid, $rstatus) = @_;
		1578
		1579	$_->($rpid, $rstatus)
997	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1580	for values %{ $PID_CB{$rpid} || {} },
998	(values %{ $PID_CB{0} || {} });	1581	values %{ $PID_CB{0} || {} };
999	}
1000
1001	undef $PID_IDLE;
1002	}	1582	}
1003		1583
1004	sub _sigchld {	1584	sub _sigchld {
1005	# make sure we deliver these changes "synchronous" with the event loop.	1585	my $pid;
1006	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1586
1007	undef $CHLD_DELAY_W;	1587	AnyEvent->_emit_childstatus ($pid, $?)
1008	&_child_wait;	1588	while ($pid = waitpid -1, $WNOHANG) > 0;
1009	});
1010	}	1589	}
1011		1590
1012	sub child {	1591	sub child {
1013	my (undef, %arg) = @_;	1592	my (undef, %arg) = @_;
1014		1593
1015	defined (my $pid = $arg{pid} + 0)	1594	defined (my $pid = $arg{pid} + 0)
1016	or Carp::croak "required option 'pid' is missing";	1595	or Carp::croak "required option 'pid' is missing";
1017		1596
1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1597	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1019		1598
1020	unless ($WNOHANG) {	1599	# WNOHANG is almost cetrainly 1 everywhere
		1600	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1601	? 1
1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1602	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1022	}
1023		1603
1024	unless ($CHLD_W) {	1604	unless ($CHLD_W) {
1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1605	$CHLD_W = AE::signal CHLD => \&_sigchld;
1026	# child could be a zombie already, so make at least one round	1606	# child could be a zombie already, so make at least one round
1027	&_sigchld;	1607	&_sigchld;
1028	}	1608	}
1029		1609
1030	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1610	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1031	}	1611	}
1032		1612
1033	sub AnyEvent::Base::Child::DESTROY {	1613	sub AnyEvent::Base::child::DESTROY {
1034	my ($pid, $cb) = @{$_[0]};	1614	my ($pid, $cb) = @{$_[0]};
1035		1615
1036	delete $PID_CB{$pid}{$cb};	1616	delete $PID_CB{$pid}{$cb};
1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1617	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1038		1618
1039	undef $CHLD_W unless keys %PID_CB;	1619	undef $CHLD_W unless keys %PID_CB;
1040	}	1620	}
1041		1621
		1622	# idle emulation is done by simply using a timer, regardless
		1623	# of whether the process is idle or not, and not letting
		1624	# the callback use more than 50% of the time.
		1625	sub idle {
		1626	my (undef, %arg) = @_;
		1627
		1628	my ($cb, $w, $rcb) = $arg{cb};
		1629
		1630	$rcb = sub {
		1631	if ($cb) {
		1632	$w = _time;
		1633	&$cb;
		1634	$w = _time - $w;
		1635
		1636	# never use more then 50% of the time for the idle watcher,
		1637	# within some limits
		1638	$w = 0.0001 if $w < 0.0001;
		1639	$w = 5 if $w > 5;
		1640
		1641	$w = AE::timer $w, 0, $rcb;
		1642	} else {
		1643	# clean up...
		1644	undef $w;
		1645	undef $rcb;
		1646	}
		1647	};
		1648
		1649	$w = AE::timer 0.05, 0, $rcb;
		1650
		1651	bless \\$cb, "AnyEvent::Base::idle"
		1652	}
		1653
		1654	sub AnyEvent::Base::idle::DESTROY {
		1655	undef $${$_[0]};
		1656	}
		1657
1042	package AnyEvent::CondVar;	1658	package AnyEvent::CondVar;
1043		1659
1044	our @ISA = AnyEvent::CondVar::Base::;	1660	our @ISA = AnyEvent::CondVar::Base::;
1045		1661
1046	package AnyEvent::CondVar::Base;	1662	package AnyEvent::CondVar::Base;
1047		1663
1048	use overload	1664	#use overload
1049	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1665	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1050	fallback => 1;	1666	# fallback => 1;
		1667
		1668	# save 300+ kilobytes by dirtily hardcoding overloading
		1669	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1670	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1671	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1672	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1673
		1674	our $WAITING;
1051		1675
1052	sub _send {	1676	sub _send {
1053	# nop	1677	# nop
1054	}	1678	}
1055		1679
…		…
1068	sub ready {	1692	sub ready {
1069	$_[0]{_ae_sent}	1693	$_[0]{_ae_sent}
1070	}	1694	}
1071		1695
1072	sub _wait {	1696	sub _wait {
		1697	$WAITING
		1698	and !$_[0]{_ae_sent}
		1699	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1700
		1701	local $WAITING = 1;
1073	AnyEvent->one_event while !$_[0]{_ae_sent};	1702	AnyEvent->one_event while !$_[0]{_ae_sent};
1074	}	1703	}
1075		1704
1076	sub recv {	1705	sub recv {
1077	$_[0]->_wait;	1706	$_[0]->_wait;
…		…
1079	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1708	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1080	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1709	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1081	}	1710	}
1082		1711
1083	sub cb {	1712	sub cb {
1084	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1713	my $cv = shift;
		1714
		1715	@_
		1716	and $cv->{_ae_cb} = shift
		1717	and $cv->{_ae_sent}
		1718	and (delete $cv->{_ae_cb})->($cv);
		1719
1085	$_[0]{_ae_cb}	1720	$cv->{_ae_cb}
1086	}	1721	}
1087		1722
1088	sub begin {	1723	sub begin {
1089	++$_[0]{_ae_counter};	1724	++$_[0]{_ae_counter};
1090	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1725	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1096	}	1731	}
1097		1732
1098	# undocumented/compatibility with pre-3.4	1733	# undocumented/compatibility with pre-3.4
1099	*broadcast = \&send;	1734	*broadcast = \&send;
1100	*wait = \&_wait;	1735	*wait = \&_wait;
		1736
		1737	=head1 ERROR AND EXCEPTION HANDLING
		1738
		1739	In general, AnyEvent does not do any error handling - it relies on the
		1740	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1741	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1742	checking of all AnyEvent methods, however, which is highly useful during
		1743	development.
		1744
		1745	As for exception handling (i.e. runtime errors and exceptions thrown while
		1746	executing a callback), this is not only highly event-loop specific, but
		1747	also not in any way wrapped by this module, as this is the job of the main
		1748	program.
		1749
		1750	The pure perl event loop simply re-throws the exception (usually
		1751	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1752	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1753	so on.
		1754
		1755	=head1 ENVIRONMENT VARIABLES
		1756
		1757	The following environment variables are used by this module or its
		1758	submodules.
		1759
		1760	Note that AnyEvent will remove I<all> environment variables starting with
		1761	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1762	enabled.
		1763
		1764	=over 4
		1765
		1766	=item C<PERL_ANYEVENT_VERBOSE>
		1767
		1768	By default, AnyEvent will be completely silent except in fatal
		1769	conditions. You can set this environment variable to make AnyEvent more
		1770	talkative.
		1771
		1772	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1773	conditions, such as not being able to load the event model specified by
		1774	C<PERL_ANYEVENT_MODEL>.
		1775
		1776	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1777	model it chooses.
		1778
		1779	When set to C<8> or higher, then AnyEvent will report extra information on
		1780	which optional modules it loads and how it implements certain features.
		1781
		1782	=item C<PERL_ANYEVENT_STRICT>
		1783
		1784	AnyEvent does not do much argument checking by default, as thorough
		1785	argument checking is very costly. Setting this variable to a true value
		1786	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1787	check the arguments passed to most method calls. If it finds any problems,
		1788	it will croak.
		1789
		1790	In other words, enables "strict" mode.
		1791
		1792	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1793	>>, it is definitely recommended to keep it off in production. Keeping
		1794	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1795	can be very useful, however.
		1796
		1797	=item C<PERL_ANYEVENT_MODEL>
		1798
		1799	This can be used to specify the event model to be used by AnyEvent, before
		1800	auto detection and -probing kicks in. It must be a string consisting
		1801	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1802	and the resulting module name is loaded and if the load was successful,
		1803	used as event model. If it fails to load AnyEvent will proceed with
		1804	auto detection and -probing.
		1805
		1806	This functionality might change in future versions.
		1807
		1808	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1809	could start your program like this:
		1810
		1811	PERL_ANYEVENT_MODEL=Perl perl ...
		1812
		1813	=item C<PERL_ANYEVENT_PROTOCOLS>
		1814
		1815	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1816	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1817	of auto probing).
		1818
		1819	Must be set to a comma-separated list of protocols or address families,
		1820	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1821	used, and preference will be given to protocols mentioned earlier in the
		1822	list.
		1823
		1824	This variable can effectively be used for denial-of-service attacks
		1825	against local programs (e.g. when setuid), although the impact is likely
		1826	small, as the program has to handle conenction and other failures anyways.
		1827
		1828	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1829	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1830	- only support IPv4, never try to resolve or contact IPv6
		1831	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1832	IPv6, but prefer IPv6 over IPv4.
		1833
		1834	=item C<PERL_ANYEVENT_EDNS0>
		1835
		1836	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1837	for DNS. This extension is generally useful to reduce DNS traffic, but
		1838	some (broken) firewalls drop such DNS packets, which is why it is off by
		1839	default.
		1840
		1841	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1842	EDNS0 in its DNS requests.
		1843
		1844	=item C<PERL_ANYEVENT_MAX_FORKS>
		1845
		1846	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1847	will create in parallel.
		1848
		1849	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1850
		1851	The default value for the C<max_outstanding> parameter for the default DNS
		1852	resolver - this is the maximum number of parallel DNS requests that are
		1853	sent to the DNS server.
		1854
		1855	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1856
		1857	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1858	configuration) in the default resolver. When set to the empty string, no
		1859	default config will be used.
		1860
		1861	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1862
		1863	When neither C<ca_file> nor C<ca_path> was specified during
		1864	L<AnyEvent::TLS> context creation, and either of these environment
		1865	variables exist, they will be used to specify CA certificate locations
		1866	instead of a system-dependent default.
		1867
		1868	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1869
		1870	When these are set to C<1>, then the respective modules are not
		1871	loaded. Mostly good for testing AnyEvent itself.
		1872
		1873	=back
1101		1874
1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1875	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1103		1876
1104	This is an advanced topic that you do not normally need to use AnyEvent in	1877	This is an advanced topic that you do not normally need to use AnyEvent in
1105	a module. This section is only of use to event loop authors who want to	1878	a module. This section is only of use to event loop authors who want to
…		…
1139		1912
1140	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1913	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1141	condition variables: code blocking while waiting for a condition will	1914	condition variables: code blocking while waiting for a condition will
1142	C<die>. This still works with most modules/usages, and blocking calls must	1915	C<die>. This still works with most modules/usages, and blocking calls must
1143	not be done in an interactive application, so it makes sense.	1916	not be done in an interactive application, so it makes sense.
1144
1145	=head1 ENVIRONMENT VARIABLES
1146
1147	The following environment variables are used by this module:
1148
1149	=over 4
1150
1151	=item C<PERL_ANYEVENT_VERBOSE>
1152
1153	By default, AnyEvent will be completely silent except in fatal
1154	conditions. You can set this environment variable to make AnyEvent more
1155	talkative.
1156
1157	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1158	conditions, such as not being able to load the event model specified by
1159	C<PERL_ANYEVENT_MODEL>.
1160
1161	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1162	model it chooses.
1163
1164	=item C<PERL_ANYEVENT_MODEL>
1165
1166	This can be used to specify the event model to be used by AnyEvent, before
1167	auto detection and -probing kicks in. It must be a string consisting
1168	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1169	and the resulting module name is loaded and if the load was successful,
1170	used as event model. If it fails to load AnyEvent will proceed with
1171	auto detection and -probing.
1172
1173	This functionality might change in future versions.
1174
1175	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1176	could start your program like this:
1177
1178	PERL_ANYEVENT_MODEL=Perl perl ...
1179
1180	=item C<PERL_ANYEVENT_PROTOCOLS>
1181
1182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1184	of auto probing).
1185
1186	Must be set to a comma-separated list of protocols or address families,
1187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1188	used, and preference will be given to protocols mentioned earlier in the
1189	list.
1190
1191	This variable can effectively be used for denial-of-service attacks
1192	against local programs (e.g. when setuid), although the impact is likely
1193	small, as the program has to handle connection errors already-
1194
1195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1197	- only support IPv4, never try to resolve or contact IPv6
1198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1199	IPv6, but prefer IPv6 over IPv4.
1200
1201	=item C<PERL_ANYEVENT_EDNS0>
1202
1203	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1204	for DNS. This extension is generally useful to reduce DNS traffic, but
1205	some (broken) firewalls drop such DNS packets, which is why it is off by
1206	default.
1207
1208	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1209	EDNS0 in its DNS requests.
1210
1211	=item C<PERL_ANYEVENT_MAX_FORKS>
1212
1213	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1214	will create in parallel.
1215
1216	=back
1217		1917
1218	=head1 EXAMPLE PROGRAM	1918	=head1 EXAMPLE PROGRAM
1219		1919
1220	The following program uses an I/O watcher to read data from STDIN, a timer	1920	The following program uses an I/O watcher to read data from STDIN, a timer
1221	to display a message once per second, and a condition variable to quit the	1921	to display a message once per second, and a condition variable to quit the
…		…
1234	warn "read: $input\n"; # output what has been read	1934	warn "read: $input\n"; # output what has been read
1235	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1935	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1236	},	1936	},
1237	);	1937	);
1238		1938
1239	my $time_watcher; # can only be used once
1240
1241	sub new_timer {
1242	$timer = AnyEvent->timer (after => 1, cb => sub {	1939	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1243	warn "timeout\n"; # print 'timeout' about every second	1940	warn "timeout\n"; # print 'timeout' at most every second
1244	&new_timer; # and restart the time
1245	});	1941	});
1246	}
1247
1248	new_timer; # create first timer
1249		1942
1250	$cv->recv; # wait until user enters /^q/i	1943	$cv->recv; # wait until user enters /^q/i
1251		1944
1252	=head1 REAL-WORLD EXAMPLE	1945	=head1 REAL-WORLD EXAMPLE
1253		1946
…		…
1384	through AnyEvent. The benchmark creates a lot of timers (with a zero	2077	through AnyEvent. The benchmark creates a lot of timers (with a zero
1385	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2078	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1386	which it is), lets them fire exactly once and destroys them again.	2079	which it is), lets them fire exactly once and destroys them again.
1387		2080
1388	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2081	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1389	distribution.	2082	distribution. It uses the L<AE> interface, which makes a real difference
		2083	for the EV and Perl backends only.
1390		2084
1391	=head3 Explanation of the columns	2085	=head3 Explanation of the columns
1392		2086
1393	I<watcher> is the number of event watchers created/destroyed. Since	2087	I<watcher> is the number of event watchers created/destroyed. Since
1394	different event models feature vastly different performances, each event	2088	different event models feature vastly different performances, each event
…		…
1415	watcher.	2109	watcher.
1416		2110
1417	=head3 Results	2111	=head3 Results
1418		2112
1419	name watchers bytes create invoke destroy comment	2113	name watchers bytes create invoke destroy comment
1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2114	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2115	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2116	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2117	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2118	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2119	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2120	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2121	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2122	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2123	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2124	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2125	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1430		2126
1431	=head3 Discussion	2127	=head3 Discussion
1432		2128
1433	The benchmark does I<not> measure scalability of the event loop very	2129	The benchmark does I<not> measure scalability of the event loop very
1434	well. For example, a select-based event loop (such as the pure perl one)	2130	well. For example, a select-based event loop (such as the pure perl one)
…		…
1446	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2142	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1447	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2143	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1448	cycles with POE.	2144	cycles with POE.
1449		2145
1450	C<EV> is the sole leader regarding speed and memory use, which are both	2146	C<EV> is the sole leader regarding speed and memory use, which are both
1451	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2147	maximal/minimal, respectively. When using the L<AE> API there is zero
		2148	overhead (when going through the AnyEvent API create is about 5-6 times
		2149	slower, with other times being equal, so still uses far less memory than
1452	far less memory than any other event loop and is still faster than Event	2150	any other event loop and is still faster than Event natively).
1453	natively.
1454		2151
1455	The pure perl implementation is hit in a few sweet spots (both the	2152	The pure perl implementation is hit in a few sweet spots (both the
1456	constant timeout and the use of a single fd hit optimisations in the perl	2153	constant timeout and the use of a single fd hit optimisations in the perl
1457	interpreter and the backend itself). Nevertheless this shows that it	2154	interpreter and the backend itself). Nevertheless this shows that it
1458	adds very little overhead in itself. Like any select-based backend its	2155	adds very little overhead in itself. Like any select-based backend its
1459	performance becomes really bad with lots of file descriptors (and few of	2156	performance becomes really bad with lots of file descriptors (and few of
1460	them active), of course, but this was not subject of this benchmark.	2157	them active), of course, but this was not subject of this benchmark.
1461		2158
1462	The C<Event> module has a relatively high setup and callback invocation	2159	The C<Event> module has a relatively high setup and callback invocation
1463	cost, but overall scores in on the third place.	2160	cost, but overall scores in on the third place.
		2161
		2162	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2163	when using its pure perl backend.
1464		2164
1465	C<Glib>'s memory usage is quite a bit higher, but it features a	2165	C<Glib>'s memory usage is quite a bit higher, but it features a
1466	faster callback invocation and overall ends up in the same class as	2166	faster callback invocation and overall ends up in the same class as
1467	C<Event>. However, Glib scales extremely badly, doubling the number of	2167	C<Event>. However, Glib scales extremely badly, doubling the number of
1468	watchers increases the processing time by more than a factor of four,	2168	watchers increases the processing time by more than a factor of four,
…		…
1529	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2229	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1530	(1%) are active. This mirrors the activity of large servers with many	2230	(1%) are active. This mirrors the activity of large servers with many
1531	connections, most of which are idle at any one point in time.	2231	connections, most of which are idle at any one point in time.
1532		2232
1533	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2233	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1534	distribution.	2234	distribution. It uses the L<AE> interface, which makes a real difference
		2235	for the EV and Perl backends only.
1535		2236
1536	=head3 Explanation of the columns	2237	=head3 Explanation of the columns
1537		2238
1538	I<sockets> is the number of sockets, and twice the number of "servers" (as	2239	I<sockets> is the number of sockets, and twice the number of "servers" (as
1539	each server has a read and write socket end).	2240	each server has a read and write socket end).
…		…
1546	it to another server. This includes deleting the old timeout and creating	2247	it to another server. This includes deleting the old timeout and creating
1547	a new one that moves the timeout into the future.	2248	a new one that moves the timeout into the future.
1548		2249
1549	=head3 Results	2250	=head3 Results
1550		2251
1551	name sockets create request	2252	name sockets create request
1552	EV 20000 69.01 11.16	2253	EV 20000 62.66 7.99
1553	Perl 20000 73.32 35.87	2254	Perl 20000 68.32 32.64
1554	Event 20000 212.62 257.32	2255	IOAsync 20000 174.06 101.15 epoll
1555	Glib 20000 651.16 1896.30	2256	IOAsync 20000 174.67 610.84 poll
		2257	Event 20000 202.69 242.91
		2258	Glib 20000 557.01 1689.52
1556	POE 20000 349.67 12317.24 uses POE::Loop::Event	2259	POE 20000 341.54 12086.32 uses POE::Loop::Event
1557		2260
1558	=head3 Discussion	2261	=head3 Discussion
1559		2262
1560	This benchmark I<does> measure scalability and overall performance of the	2263	This benchmark I<does> measure scalability and overall performance of the
1561	particular event loop.	2264	particular event loop.
…		…
1563	EV is again fastest. Since it is using epoll on my system, the setup time	2266	EV is again fastest. Since it is using epoll on my system, the setup time
1564	is relatively high, though.	2267	is relatively high, though.
1565		2268
1566	Perl surprisingly comes second. It is much faster than the C-based event	2269	Perl surprisingly comes second. It is much faster than the C-based event
1567	loops Event and Glib.	2270	loops Event and Glib.
		2271
		2272	IO::Async performs very well when using its epoll backend, and still quite
		2273	good compared to Glib when using its pure perl backend.
1568		2274
1569	Event suffers from high setup time as well (look at its code and you will	2275	Event suffers from high setup time as well (look at its code and you will
1570	understand why). Callback invocation also has a high overhead compared to	2276	understand why). Callback invocation also has a high overhead compared to
1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2277	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1572	uses select or poll in basically all documented configurations.	2278	uses select or poll in basically all documented configurations.
…		…
1635	=item * C-based event loops perform very well with small number of	2341	=item * C-based event loops perform very well with small number of
1636	watchers, as the management overhead dominates.	2342	watchers, as the management overhead dominates.
1637		2343
1638	=back	2344	=back
1639		2345
		2346	=head2 THE IO::Lambda BENCHMARK
		2347
		2348	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2349	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2350	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2351	shouldn't come as a surprise to anybody). As such, the benchmark is
		2352	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2353	very optimal. But how would AnyEvent compare when used without the extra
		2354	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2355
		2356	The benchmark itself creates an echo-server, and then, for 500 times,
		2357	connects to the echo server, sends a line, waits for the reply, and then
		2358	creates the next connection. This is a rather bad benchmark, as it doesn't
		2359	test the efficiency of the framework or much non-blocking I/O, but it is a
		2360	benchmark nevertheless.
		2361
		2362	name runtime
		2363	Lambda/select 0.330 sec
		2364	+ optimized 0.122 sec
		2365	Lambda/AnyEvent 0.327 sec
		2366	+ optimized 0.138 sec
		2367	Raw sockets/select 0.077 sec
		2368	POE/select, components 0.662 sec
		2369	POE/select, raw sockets 0.226 sec
		2370	POE/select, optimized 0.404 sec
		2371
		2372	AnyEvent/select/nb 0.085 sec
		2373	AnyEvent/EV/nb 0.068 sec
		2374	+state machine 0.134 sec
		2375
		2376	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2377	benchmarks actually make blocking connects and use 100% blocking I/O,
		2378	defeating the purpose of an event-based solution. All of the newly
		2379	written AnyEvent benchmarks use 100% non-blocking connects (using
		2380	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2381	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2382	generally require a lot more bookkeeping and event handling than blocking
		2383	connects (which involve a single syscall only).
		2384
		2385	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2386	offers similar expressive power as POE and IO::Lambda, using conventional
		2387	Perl syntax. This means that both the echo server and the client are 100%
		2388	non-blocking, further placing it at a disadvantage.
		2389
		2390	As you can see, the AnyEvent + EV combination even beats the
		2391	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2392	backend easily beats IO::Lambda and POE.
		2393
		2394	And even the 100% non-blocking version written using the high-level (and
		2395	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2396	higher level ("unoptimised") abstractions by a large margin, even though
		2397	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2398
		2399	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2400	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2401	part of the IO::Lambda distribution and were used without any changes.
		2402
		2403
		2404	=head1 SIGNALS
		2405
		2406	AnyEvent currently installs handlers for these signals:
		2407
		2408	=over 4
		2409
		2410	=item SIGCHLD
		2411
		2412	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2413	emulation for event loops that do not support them natively. Also, some
		2414	event loops install a similar handler.
		2415
		2416	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2417	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2418
		2419	=item SIGPIPE
		2420
		2421	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2422	when AnyEvent gets loaded.
		2423
		2424	The rationale for this is that AnyEvent users usually do not really depend
		2425	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2426	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2427	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2428	some random socket.
		2429
		2430	The rationale for installing a no-op handler as opposed to ignoring it is
		2431	that this way, the handler will be restored to defaults on exec.
		2432
		2433	Feel free to install your own handler, or reset it to defaults.
		2434
		2435	=back
		2436
		2437	=cut
		2438
		2439	undef $SIG{CHLD}
		2440	if $SIG{CHLD} eq 'IGNORE';
		2441
		2442	$SIG{PIPE} = sub { }
		2443	unless defined $SIG{PIPE};
		2444
		2445	=head1 RECOMMENDED/OPTIONAL MODULES
		2446
		2447	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2448	it's built-in modules) are required to use it.
		2449
		2450	That does not mean that AnyEvent won't take advantage of some additional
		2451	modules if they are installed.
		2452
		2453	This section explains which additional modules will be used, and how they
		2454	affect AnyEvent's operation.
		2455
		2456	=over 4
		2457
		2458	=item L<Async::Interrupt>
		2459
		2460	This slightly arcane module is used to implement fast signal handling: To
		2461	my knowledge, there is no way to do completely race-free and quick
		2462	signal handling in pure perl. To ensure that signals still get
		2463	delivered, AnyEvent will start an interval timer to wake up perl (and
		2464	catch the signals) with some delay (default is 10 seconds, look for
		2465	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2466
		2467	If this module is available, then it will be used to implement signal
		2468	catching, which means that signals will not be delayed, and the event loop
		2469	will not be interrupted regularly, which is more efficient (and good for
		2470	battery life on laptops).
		2471
		2472	This affects not just the pure-perl event loop, but also other event loops
		2473	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2474
		2475	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2476	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2477	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2478	does nothing for those backends.
		2479
		2480	=item L<EV>
		2481
		2482	This module isn't really "optional", as it is simply one of the backend
		2483	event loops that AnyEvent can use. However, it is simply the best event
		2484	loop available in terms of features, speed and stability: It supports
		2485	the AnyEvent API optimally, implements all the watcher types in XS, does
		2486	automatic timer adjustments even when no monotonic clock is available,
		2487	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2488	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2489	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2490
		2491	=item L<Guard>
		2492
		2493	The guard module, when used, will be used to implement
		2494	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2495	lot less memory), but otherwise doesn't affect guard operation much. It is
		2496	purely used for performance.
		2497
		2498	=item L<JSON> and L<JSON::XS>
		2499
		2500	One of these modules is required when you want to read or write JSON data
		2501	via L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2502	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2503
		2504	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2505	installed.
		2506
		2507	=item L<Net::SSLeay>
		2508
		2509	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2510	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2511	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2512
		2513	=item L<Time::HiRes>
		2514
		2515	This module is part of perl since release 5.008. It will be used when the
		2516	chosen event library does not come with a timing source on it's own. The
		2517	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2518	try to use a monotonic clock for timing stability.
		2519
		2520	=back
		2521
1640		2522
1641	=head1 FORK	2523	=head1 FORK
1642		2524
1643	Most event libraries are not fork-safe. The ones who are usually are	2525	Most event libraries are not fork-safe. The ones who are usually are
1644	because they rely on inefficient but fork-safe C<select> or C<poll>	2526	because they rely on inefficient but fork-safe C<select> or C<poll>
1645	calls. Only L<EV> is fully fork-aware.	2527	calls. Only L<EV> is fully fork-aware.
1646		2528
		2529	This means that, in general, you cannot fork and do event processing
		2530	in the child if a watcher was created before the fork (which in turn
		2531	initialises the event library).
		2532
1647	If you have to fork, you must either do so I<before> creating your first	2533	If you have to fork, you must either do so I<before> creating your first
1648	watcher OR you must not use AnyEvent at all in the child.	2534	watcher OR you must not use AnyEvent at all in the child OR you must do
		2535	something completely out of the scope of AnyEvent.
		2536
		2537	The problem of doing event processing in the parent I<and> the child
		2538	is much more complicated: even for backends that I<are> fork-aware or
		2539	fork-safe, their behaviour is not usually what you want: fork clones all
		2540	watchers, that means all timers, I/O watchers etc. are active in both
		2541	parent and child, which is almost never what you want.
1649		2542
1650		2543
1651	=head1 SECURITY CONSIDERATIONS	2544	=head1 SECURITY CONSIDERATIONS
1652		2545
1653	AnyEvent can be forced to load any event model via	2546	AnyEvent can be forced to load any event model via
…		…
1664		2557
1665	use AnyEvent;	2558	use AnyEvent;
1666		2559
1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2560	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1668	be used to probe what backend is used and gain other information (which is	2561	be used to probe what backend is used and gain other information (which is
1669	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2562	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2563	$ENV{PERL_ANYEVENT_STRICT}.
		2564
		2565	Note that AnyEvent will remove I<all> environment variables starting with
		2566	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2567	enabled.
		2568
		2569
		2570	=head1 BUGS
		2571
		2572	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2573	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2574	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2575	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2576	pronounced).
1670		2577
1671		2578
1672	=head1 SEE ALSO	2579	=head1 SEE ALSO
1673		2580
1674	Utility functions: L<AnyEvent::Util>.	2581	Utility functions: L<AnyEvent::Util>.
…		…
1677	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2584	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1678		2585
1679	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2586	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1680	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2587	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1681	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2588	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1682	L<AnyEvent::Impl::POE>.	2589	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1683		2590
1684	Non-blocking file handles, sockets, TCP clients and	2591	Non-blocking file handles, sockets, TCP clients and
1685	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2592	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1686		2593
1687	Asynchronous DNS: L<AnyEvent::DNS>.	2594	Asynchronous DNS: L<AnyEvent::DNS>.
1688		2595
1689	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2596	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2597	L<Coro::Event>,
1690		2598
1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2599	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2600	L<AnyEvent::HTTP>.
1692		2601
1693		2602
1694	=head1 AUTHOR	2603	=head1 AUTHOR
1695		2604
1696	Marc Lehmann <schmorp@schmorp.de>	2605	Marc Lehmann <schmorp@schmorp.de>

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