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Revision 1.320 by root, Mon Apr 12 02:50:31 2010 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the L<AE> manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
22		42
23	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
24		44
25	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
28		48
		49	=head1 SUPPORT
		50
		51	There is a mailinglist for discussing all things AnyEvent, and an IRC
		52	channel, too.
		53
		54	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		55	Repository>, at L<http://anyevent.schmorp.de>, for more info.
		56
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	57	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		58
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	59	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	60	nowadays. So what is different about AnyEvent?
33		61
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	62	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	63	policy> and AnyEvent is I<small and efficient>.
36		64
37	First and foremost, I<AnyEvent is not an event model> itself, it only	65	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	66	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,	67	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,	68	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	69	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	70	cannot change this, but it can hide the differences between those event
		71	loops.
43		72
44	The goal of AnyEvent is to offer module authors the ability to do event	73	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	74	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	75	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	76	module users into the same thing by forcing them to use the same event
48	model you use.	77	model you use.
49		78
50	For modules like POE or IO::Async (which is a total misnomer as it is	79	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	80	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	81	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	82	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	83	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.	84	module are I<also> forced to use the same event loop you use.
56		85
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	87	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	88	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,	89	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	90	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	91	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	92	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).	93	to AnyEvent, too, so it is future-proof).
65		94
66	In addition to being free of having to use I<the one and only true event	95	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	96	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	97	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	98	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	156	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	157	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	158	callback when the event occurs (of course, only when the event model
130	is in control).	159	is in control).
131		160
		161	Note that B<callbacks must not permanently change global variables>
		162	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		163	callbacks must not C<die> >>. The former is good programming practise in
		164	Perl and the latter stems from the fact that exception handling differs
		165	widely between event loops.
		166
132	To disable the watcher you have to destroy it (e.g. by setting the	167	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	168	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	169	to it).
135		170
136	All watchers are created by calling a method on the C<AnyEvent> class.	171	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	184	my variables are only visible after the statement in which they are
150	declared.	185	declared.
151		186
152	=head2 I/O WATCHERS	187	=head2 I/O WATCHERS
153		188
		189	$w = AnyEvent->io (
		190	fh => <filehandle_or_fileno>,
		191	poll => <"r" or "w">,
		192	cb => <callback>,
		193	);
		194
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	195	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	196	with the following mandatory key-value pairs as arguments:
156		197
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	198	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		199	for events (AnyEvent might or might not keep a reference to this file
		200	handle). Note that only file handles pointing to things for which
		201	non-blocking operation makes sense are allowed. This includes sockets,
		202	most character devices, pipes, fifos and so on, but not for example files
		203	or block devices.
		204
158	for events. C<poll> must be a string that is either C<r> or C<w>,	205	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,	206	watcher waiting for "r"eadable or "w"ritable events, respectively.
		207
160	respectively. C<cb> is the callback to invoke each time the file handle	208	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		209
163	Although the callback might get passed parameters, their value and	210	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	211	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	212	callbacks cannot use arguments passed to I/O watcher callbacks.
166		213
…		…
170		217
171	Some event loops issue spurious readyness notifications, so you should	218	Some event loops issue spurious readyness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	219	always use non-blocking calls when reading/writing from/to your file
173	handles.	220	handles.
174		221
175	Example:
176
177	# wait for readability of STDIN, then read a line and disable the watcher	222	Example: wait for readability of STDIN, then read a line and disable the
		223	watcher.
		224
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	225	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	226	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	227	warn "read: $input\n";
181	undef $w;	228	undef $w;
182	});	229	});
183		230
184	=head2 TIME WATCHERS	231	=head2 TIME WATCHERS
185		232
		233	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		234
		235	$w = AnyEvent->timer (
		236	after => <fractional_seconds>,
		237	interval => <fractional_seconds>,
		238	cb => <callback>,
		239	);
		240
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	241	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	242	method with the following mandatory arguments:
188		243
189	C<after> specifies after how many seconds (fractional values are	244	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	245	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		247
193	Although the callback might get passed parameters, their value and	248	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	249	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	250	callbacks cannot use arguments passed to time watcher callbacks.
196		251
197	The timer callback will be invoked at most once: if you want a repeating	252	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	253	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	254	callback will be invoked regularly at that interval (in fractional
		255	seconds) after the first invocation. If C<interval> is specified with a
		256	false value, then it is treated as if it were missing.
200		257
201	Example:	258	The callback will be rescheduled before invoking the callback, but no
		259	attempt is done to avoid timer drift in most backends, so the interval is
		260	only approximate.
202		261
203	# fire an event after 7.7 seconds	262	Example: fire an event after 7.7 seconds.
		263
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	264	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	265	warn "timeout\n";
206	});	266	});
207		267
208	# to cancel the timer:	268	# to cancel the timer:
209	undef $w;	269	undef $w;
210		270
211	Example 2:
212
213	# fire an event after 0.5 seconds, then roughly every second	271	Example 2: fire an event after 0.5 seconds, then roughly every second.
214	my $w;
215		272
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	273	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		274	warn "timeout\n";
219	};	275	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		276
224	=head3 TIMING ISSUES	277	=head3 TIMING ISSUES
225		278
226	There are two ways to handle timers: based on real time (relative, "fire	279	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	280	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	353	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	354	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	355	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	356	account.
304		357
		358	=item AnyEvent->now_update
		359
		360	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		361	the current time for each loop iteration (see the discussion of L<<
		362	AnyEvent->now >>, above).
		363
		364	When a callback runs for a long time (or when the process sleeps), then
		365	this "current" time will differ substantially from the real time, which
		366	might affect timers and time-outs.
		367
		368	When this is the case, you can call this method, which will update the
		369	event loop's idea of "current time".
		370
		371	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		372	when mod_perl executes the script, then the event loop will have the wrong
		373	idea about the "current time" (being potentially far in the past, when the
		374	script ran the last time). In that case you should arrange a call to C<<
		375	AnyEvent->now_update >> each time the web server process wakes up again
		376	(e.g. at the start of your script, or in a handler).
		377
		378	Note that updating the time I<might> cause some events to be handled.
		379
305	=back	380	=back
306		381
307	=head2 SIGNAL WATCHERS	382	=head2 SIGNAL WATCHERS
308		383
		384	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		385
309	You can watch for signals using a signal watcher, C<signal> is the signal	386	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	387	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311	be invoked whenever a signal occurs.	388	callback to be invoked whenever a signal occurs.
312		389
313	Although the callback might get passed parameters, their value and	390	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	391	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	392	callbacks cannot use arguments passed to signal watcher callbacks.
316		393
…		…
318	invocation, and callback invocation will be synchronous. Synchronous means	395	invocation, and callback invocation will be synchronous. Synchronous means
319	that it might take a while until the signal gets handled by the process,	396	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.	397	but it is guaranteed not to interrupt any other callbacks.
321		398
322	The main advantage of using these watchers is that you can share a signal	399	The main advantage of using these watchers is that you can share a signal
323	between multiple watchers.	400	between multiple watchers, and AnyEvent will ensure that signals will not
		401	interrupt your program at bad times.
324		402
325	This watcher might use C<%SIG>, so programs overwriting those signals	403	This watcher might use C<%SIG> (depending on the event loop used),
326	directly will likely not work correctly.	404	so programs overwriting those signals directly will likely not work
		405	correctly.
327		406
328	Example: exit on SIGINT	407	Example: exit on SIGINT
329		408
330	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	409	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		410
		411	=head3 Restart Behaviour
		412
		413	While restart behaviour is up to the event loop implementation, most will
		414	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		415	pure perl implementation).
		416
		417	=head3 Safe/Unsafe Signals
		418
		419	Perl signals can be either "safe" (synchronous to opcode handling) or
		420	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		421	latter might corrupt your memory.
		422
		423	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		424	i.e. they will not interrupt your running perl program but will only be
		425	called as part of the normal event handling (just like timer, I/O etc.
		426	callbacks, too).
		427
		428	=head3 Signal Races, Delays and Workarounds
		429
		430	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		431	callbacks to signals in a generic way, which is a pity, as you cannot
		432	do race-free signal handling in perl, requiring C libraries for
		433	this. AnyEvent will try to do it's best, which means in some cases,
		434	signals will be delayed. The maximum time a signal might be delayed is
		435	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		436	variable can be changed only before the first signal watcher is created,
		437	and should be left alone otherwise. This variable determines how often
		438	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		439	will cause fewer spurious wake-ups, which is better for power and CPU
		440	saving.
		441
		442	All these problems can be avoided by installing the optional
		443	L<Async::Interrupt> module, which works with most event loops. It will not
		444	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		445	(and not with L<POE> currently, as POE does it's own workaround with
		446	one-second latency). For those, you just have to suffer the delays.
		447
332	=head2 CHILD PROCESS WATCHERS	448	=head2 CHILD PROCESS WATCHERS
333		449
		450	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		451
334	You can also watch on a child process exit and catch its exit status.	452	You can also watch on a child process exit and catch its exit status.
335		453
336	The child process is specified by the C<pid> argument (if set to C<0>, it	454	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	455	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	456	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	457	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,	458	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	459
		460	The callback will be called with the pid and exit status (as returned by
		461	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		462	callback arguments.
		463
		464	This watcher type works by installing a signal handler for C<SIGCHLD>,
		465	and since it cannot be shared, nothing else should use SIGCHLD or reap
		466	random child processes (waiting for specific child processes, e.g. inside
		467	C<system>, is just fine).
342		468
343	There is a slight catch to child watchers, however: you usually start them	469	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	470	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	471	have exited already (and no SIGCHLD will be sent anymore).
346		472
347	Not all event models handle this correctly (POE doesn't), but even for	473	Not all event models handle this correctly (neither POE nor IO::Async do,
		474	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	475	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).	476	the process exits (i.e. before you fork in the first place). AnyEvent's
		477	pure perl event loop handles all cases correctly regardless of when you
		478	start the watcher.
350		479
351	This means you cannot create a child watcher as the very first thing in an	480	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	481	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>).	482	watcher before you C<fork> the child (alternatively, you can call
		483	C<AnyEvent::detect>).
		484
		485	As most event loops do not support waiting for child events, they will be
		486	emulated by AnyEvent in most cases, in which the latency and race problems
		487	mentioned in the description of signal watchers apply.
354		488
355	Example: fork a process and wait for it	489	Example: fork a process and wait for it
356		490
357	my $done = AnyEvent->condvar;	491	my $done = AnyEvent->condvar;
358		492
…		…
368	);	502	);
369		503
370	# do something else, then wait for process exit	504	# do something else, then wait for process exit
371	$done->recv;	505	$done->recv;
372		506
		507	=head2 IDLE WATCHERS
		508
		509	$w = AnyEvent->idle (cb => <callback>);
		510
		511	Repeatedly invoke the callback after the process becomes idle, until
		512	either the watcher is destroyed or new events have been detected.
		513
		514	Idle watchers are useful when there is a need to do something, but it
		515	is not so important (or wise) to do it instantly. The callback will be
		516	invoked only when there is "nothing better to do", which is usually
		517	defined as "all outstanding events have been handled and no new events
		518	have been detected". That means that idle watchers ideally get invoked
		519	when the event loop has just polled for new events but none have been
		520	detected. Instead of blocking to wait for more events, the idle watchers
		521	will be invoked.
		522
		523	Unfortunately, most event loops do not really support idle watchers (only
		524	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		525	will simply call the callback "from time to time".
		526
		527	Example: read lines from STDIN, but only process them when the
		528	program is otherwise idle:
		529
		530	my @lines; # read data
		531	my $idle_w;
		532	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		533	push @lines, scalar <STDIN>;
		534
		535	# start an idle watcher, if not already done
		536	$idle_w ||= AnyEvent->idle (cb => sub {
		537	# handle only one line, when there are lines left
		538	if (my $line = shift @lines) {
		539	print "handled when idle: $line";
		540	} else {
		541	# otherwise disable the idle watcher again
		542	undef $idle_w;
		543	}
		544	});
		545	});
		546
373	=head2 CONDITION VARIABLES	547	=head2 CONDITION VARIABLES
		548
		549	$cv = AnyEvent->condvar;
		550
		551	$cv->send (<list>);
		552	my @res = $cv->recv;
374		553
375	If you are familiar with some event loops you will know that all of them	554	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	555	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	556	will actively watch for new events and call your callbacks.
378		557
379	AnyEvent is different, it expects somebody else to run the event loop and	558	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	559	loop and will only block when necessary (usually when told by the user).
381		560
382	The instrument to do that is called a "condition variable", so called	561	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	562	because they represent a condition that must become true.
		563
		564	Now is probably a good time to look at the examples further below.
384		565
385	Condition variables can be created by calling the C<< AnyEvent->condvar	566	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	567	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	568	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	569	becomes true, with the condition variable as the first argument (but not
		570	the results).
389		571
390	After creation, the condition variable is "false" until it becomes "true"	572	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	573	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<<	574	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	575	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	577	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	578	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	579	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	580	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	581	used to represent a transaction, which finishes at some point and delivers
400	a result.	582	a result. And yet some people know them as "futures" - a promise to
		583	compute/deliver something that you can wait for.
401		584
402	Condition variables are very useful to signal that something has finished,	585	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	586	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	587	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	588	availability of results. The user can either act when the callback is
…		…
426	eventually calls C<< -> send >>, and the "consumer side", which waits	609	eventually calls C<< -> send >>, and the "consumer side", which waits
427	for the send to occur.	610	for the send to occur.
428		611
429	Example: wait for a timer.	612	Example: wait for a timer.
430		613
431	# wait till the result is ready	614	# condition: "wait till the timer is fired"
432	my $result_ready = AnyEvent->condvar;	615	my $timer_fired = AnyEvent->condvar;
433		616
434	# do something such as adding a timer	617	# create the timer - we could wait for, say
435	# or socket watcher the calls $result_ready->send	618	# a handle becomign ready, or even an
436	# when the "result" is ready.	619	# AnyEvent::HTTP request to finish, but
437	# in this case, we simply use a timer:	620	# in this case, we simply use a timer:
438	my $w = AnyEvent->timer (	621	my $w = AnyEvent->timer (
439	after => 1,	622	after => 1,
440	cb => sub { $result_ready->send },	623	cb => sub { $timer_fired->send },
441	);	624	);
442		625
443	# this "blocks" (while handling events) till the callback	626	# this "blocks" (while handling events) till the callback
444	# calls send	627	# calls ->send
445	$result_ready->recv;	628	$timer_fired->recv;
446		629
447	Example: wait for a timer, but take advantage of the fact that	630	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	631	variables are also callable directly.
449		632
450	my $done = AnyEvent->condvar;	633	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	634	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	635	$done->recv;
		636
		637	Example: Imagine an API that returns a condvar and doesn't support
		638	callbacks. This is how you make a synchronous call, for example from
		639	the main program:
		640
		641	use AnyEvent::CouchDB;
		642
		643	...
		644
		645	my @info = $couchdb->info->recv;
		646
		647	And this is how you would just set a callback to be called whenever the
		648	results are available:
		649
		650	$couchdb->info->cb (sub {
		651	my @info = $_[0]->recv;
		652	});
453		653
454	=head3 METHODS FOR PRODUCERS	654	=head3 METHODS FOR PRODUCERS
455		655
456	These methods should only be used by the producing side, i.e. the	656	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	657	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	670	immediately from within send.
471		671
472	Any arguments passed to the C<send> call will be returned by all	672	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	673	future C<< ->recv >> calls.
474		674
475	Condition variables are overloaded so one can call them directly	675	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	676	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	677	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		678
484	=item $cv->croak ($error)	679	=item $cv->croak ($error)
485		680
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	681	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	682	C<Carp::croak> with the given error message/object/scalar.
488		683
489	This can be used to signal any errors to the condition variable	684	This can be used to signal any errors to the condition variable
490	user/consumer.	685	user/consumer. Doing it this way instead of calling C<croak> directly
		686	delays the error detetcion, but has the overwhelmign advantage that it
		687	diagnoses the error at the place where the result is expected, and not
		688	deep in some event clalback without connection to the actual code causing
		689	the problem.
491		690
492	=item $cv->begin ([group callback])	691	=item $cv->begin ([group callback])
493		692
494	=item $cv->end	693	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		694
498	These two methods can be used to combine many transactions/events into	695	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	696	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	697	to use a condition variable for the whole process.
501		698
502	Every call to C<< ->begin >> will increment a counter, and every call to	699	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	700	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	701	>>, 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	702	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.	703	>>, but that is not required. If no group callback was set, C<send> will
		704	be called without any arguments.
507		705
508	Let's clarify this with the ping example:	706	You can think of C<< $cv->send >> giving you an OR condition (one call
		707	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		708	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		709
		710	Let's start with a simple example: you have two I/O watchers (for example,
		711	STDOUT and STDERR for a program), and you want to wait for both streams to
		712	close before activating a condvar:
509		713
510	my $cv = AnyEvent->condvar;	714	my $cv = AnyEvent->condvar;
511		715
		716	$cv->begin; # first watcher
		717	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		718	defined sysread $fh1, my $buf, 4096
		719	or $cv->end;
		720	});
		721
		722	$cv->begin; # second watcher
		723	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		724	defined sysread $fh2, my $buf, 4096
		725	or $cv->end;
		726	});
		727
		728	$cv->recv;
		729
		730	This works because for every event source (EOF on file handle), there is
		731	one call to C<begin>, so the condvar waits for all calls to C<end> before
		732	sending.
		733
		734	The ping example mentioned above is slightly more complicated, as the
		735	there are results to be passwd back, and the number of tasks that are
		736	begung can potentially be zero:
		737
		738	my $cv = AnyEvent->condvar;
		739
512	my %result;	740	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	741	$cv->begin (sub { shift->send (\%result) });
514		742
515	for my $host (@list_of_hosts) {	743	for my $host (@list_of_hosts) {
516	$cv->begin;	744	$cv->begin;
517	ping_host_then_call_callback $host, sub {	745	ping_host_then_call_callback $host, sub {
518	$result{$host} = ...;	746	$result{$host} = ...;
…		…
533	loop, which serves two important purposes: first, it sets the callback	761	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	762	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	763	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	764	doesn't execute once).
537		765
538	This is the general pattern when you "fan out" into multiple subrequests:	766	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>	767	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	768	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>.	769	subrequest you start, call C<begin> and for each subrequest you finish,
		770	call C<end>.
542		771
543	=back	772	=back
544		773
545	=head3 METHODS FOR CONSUMERS	774	=head3 METHODS FOR CONSUMERS
546		775
…		…
562	function will call C<croak>.	791	function will call C<croak>.
563		792
564	In list context, all parameters passed to C<send> will be returned,	793	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	794	in scalar context only the first one will be returned.
566		795
		796	Note that doing a blocking wait in a callback is not supported by any
		797	event loop, that is, recursive invocation of a blocking C<< ->recv
		798	>> is not allowed, and the C<recv> call will C<croak> if such a
		799	condition is detected. This condition can be slightly loosened by using
		800	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		801	any thread that doesn't run the event loop itself.
		802
567	Not all event models support a blocking wait - some die in that case	803	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	804	(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	805	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	806	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	807	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	808	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	809	while still supporting blocking waits if the caller so desires).
574		810
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	811	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	812	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	813	time). This will work even when the event loop does not support blocking
589	waits otherwise.	814	waits otherwise.
590		815
591	=item $bool = $cv->ready	816	=item $bool = $cv->ready
592		817
593	Returns true when the condition is "true", i.e. whether C<send> or	818	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	819	C<croak> have been called.
595		820
596	=item $cb = $cv->cb ([new callback])	821	=item $cb = $cv->cb ($cb->($cv))
597		822
598	This is a mutator function that returns the callback set and optionally	823	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	824	replaces it before doing so.
600		825
601	The callback will be called when the condition becomes "true", i.e. when	826	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	827	"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	828	the only argument being the condition variable itself. Calling C<recv>
604	is guaranteed not to block.	829	inside the callback or at any later time is guaranteed not to block.
605		830
606	=back	831	=back
607		832
		833	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		834
		835	The available backend classes are (every class has its own manpage):
		836
		837	=over 4
		838
		839	=item Backends that are autoprobed when no other event loop can be found.
		840
		841	EV is the preferred backend when no other event loop seems to be in
		842	use. If EV is not installed, then AnyEvent will fall back to its own
		843	pure-perl implementation, which is available everywhere as it comes with
		844	AnyEvent itself.
		845
		846	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		847	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		848
		849	=item Backends that are transparently being picked up when they are used.
		850
		851	These will be used when they are currently loaded when the first watcher
		852	is created, in which case it is assumed that the application is using
		853	them. This means that AnyEvent will automatically pick the right backend
		854	when the main program loads an event module before anything starts to
		855	create watchers. Nothing special needs to be done by the main program.
		856
		857	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		858	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		859	AnyEvent::Impl::Tk based on Tk, very broken.
		860	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		861	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		862	AnyEvent::Impl::Irssi used when running within irssi.
		863
		864	=item Backends with special needs.
		865
		866	Qt requires the Qt::Application to be instantiated first, but will
		867	otherwise be picked up automatically. As long as the main program
		868	instantiates the application before any AnyEvent watchers are created,
		869	everything should just work.
		870
		871	AnyEvent::Impl::Qt based on Qt.
		872
		873	Support for IO::Async can only be partial, as it is too broken and
		874	architecturally limited to even support the AnyEvent API. It also
		875	is the only event loop that needs the loop to be set explicitly, so
		876	it can only be used by a main program knowing about AnyEvent. See
		877	L<AnyEvent::Impl::Async> for the gory details.
		878
		879	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		880
		881	=item Event loops that are indirectly supported via other backends.
		882
		883	Some event loops can be supported via other modules:
		884
		885	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		886
		887	B<WxWidgets> has no support for watching file handles. However, you can
		888	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		889	polls 20 times per second, which was considered to be too horrible to even
		890	consider for AnyEvent.
		891
		892	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		893	backend, so it can be supported through POE.
		894
		895	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		896	load L<POE> when detecting them, in the hope that POE will pick them up,
		897	in which case everything will be automatic.
		898
		899	=back
		900
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	901	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		902
		903	These are not normally required to use AnyEvent, but can be useful to
		904	write AnyEvent extension modules.
		905
610	=over 4	906	=over 4
611		907
612	=item $AnyEvent::MODEL	908	=item $AnyEvent::MODEL
613		909
614	Contains C<undef> until the first watcher is being created. Then it	910	Contains C<undef> until the first watcher is being created, before the
		911	backend has been autodetected.
		912
615	contains the event model that is being used, which is the name of the	913	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	914	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	915	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	916	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		917	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		918
641	=item AnyEvent::detect	919	=item AnyEvent::detect
642		920
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	921	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	922	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	923	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	924	runtime, and not e.g. while initialising of your module.
		925
		926	If you need to do some initialisation before AnyEvent watchers are
		927	created, use C<post_detect>.
647		928
648	=item $guard = AnyEvent::post_detect { BLOCK }	929	=item $guard = AnyEvent::post_detect { BLOCK }
649		930
650	Arranges for the code block to be executed as soon as the event model is	931	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	932	autodetected (or immediately if this has already happened).
652		933
		934	The block will be executed I<after> the actual backend has been detected
		935	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		936	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		937	other initialisations - see the sources of L<AnyEvent::Strict> or
		938	L<AnyEvent::AIO> to see how this is used.
		939
		940	The most common usage is to create some global watchers, without forcing
		941	event module detection too early, for example, L<AnyEvent::AIO> creates
		942	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		943	avoid autodetecting the event module at load time.
		944
653	If called in scalar or list context, then it creates and returns an object	945	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	946	that automatically removes the callback again when it is destroyed (or
		947	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	948	a case where this is useful.
		949
		950	Example: Create a watcher for the IO::AIO module and store it in
		951	C<$WATCHER>. Only do so after the event loop is initialised, though.
		952
		953	our WATCHER;
		954
		955	my $guard = AnyEvent::post_detect {
		956	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		957	};
		958
		959	# the ||= is important in case post_detect immediately runs the block,
		960	# as to not clobber the newly-created watcher. assigning both watcher and
		961	# post_detect guard to the same variable has the advantage of users being
		962	# able to just C<undef $WATCHER> if the watcher causes them grief.
		963
		964	$WATCHER ||= $guard;
656		965
657	=item @AnyEvent::post_detect	966	=item @AnyEvent::post_detect
658		967
659	If there are any code references in this array (you can C<push> to it	968	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	969	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	970	the event loop has been chosen.
662		971
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	972	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,	973	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	974	array will be ignored.
666		975
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	976	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		977	it, as it takes care of these details.
		978
		979	This variable is mainly useful for modules that can do something useful
		980	when AnyEvent is used and thus want to know when it is initialised, but do
		981	not need to even load it by default. This array provides the means to hook
		982	into AnyEvent passively, without loading it.
		983
		984	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		985	together, you could put this into Coro (this is the actual code used by
		986	Coro to accomplish this):
		987
		988	if (defined $AnyEvent::MODEL) {
		989	# AnyEvent already initialised, so load Coro::AnyEvent
		990	require Coro::AnyEvent;
		991	} else {
		992	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		993	# as soon as it is
		994	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		995	}
668		996
669	=back	997	=back
670		998
671	=head1 WHAT TO DO IN A MODULE	999	=head1 WHAT TO DO IN A MODULE
672		1000
…		…
727		1055
728		1056
729	=head1 OTHER MODULES	1057	=head1 OTHER MODULES
730		1058
731	The following is a non-exhaustive list of additional modules that use	1059	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1060	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	1061	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1062	come with AnyEvent, most are available via CPAN.
735		1063
736	=over 4	1064	=over 4
737		1065
738	=item L<AnyEvent::Util>	1066	=item L<AnyEvent::Util>
739		1067
740	Contains various utility functions that replace often-used but blocking	1068	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1069	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		1070
747	=item L<AnyEvent::Socket>	1071	=item L<AnyEvent::Socket>
748		1072
749	Provides various utility functions for (internet protocol) sockets,	1073	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1074	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1075	connections or tcp servers, with IPv6 and SRV record support and more.
752		1076
		1077	=item L<AnyEvent::Handle>
		1078
		1079	Provide read and write buffers, manages watchers for reads and writes,
		1080	supports raw and formatted I/O, I/O queued and fully transparent and
		1081	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1082
753	=item L<AnyEvent::DNS>	1083	=item L<AnyEvent::DNS>
754		1084
755	Provides rich asynchronous DNS resolver capabilities.	1085	Provides rich asynchronous DNS resolver capabilities.
756		1086
757	=item L<AnyEvent::HTTP>	1087	=item L<AnyEvent::HTTP>
…		…
767		1097
768	The fastest ping in the west.	1098	The fastest ping in the west.
769		1099
770	=item L<AnyEvent::DBI>	1100	=item L<AnyEvent::DBI>
771		1101
772	Executes DBI requests asynchronously in a proxy process.	1102	Executes L<DBI> requests asynchronously in a proxy process.
773		1103
		1104	=item L<AnyEvent::AIO>
		1105
		1106	Truly asynchronous I/O, should be in the toolbox of every event
		1107	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1108	together.
		1109
		1110	=item L<AnyEvent::BDB>
		1111
		1112	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1113	L<BDB> and AnyEvent together.
		1114
		1115	=item L<AnyEvent::GPSD>
		1116
		1117	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1118
774	=item L<Net::IRC3>	1119	=item L<AnyEvent::IRC>
775		1120
776	AnyEvent based IRC client module family.	1121	AnyEvent based IRC client module family (replacing the older Net::IRC3).
777		1122
778	=item L<Net::XMPP2>	1123	=item L<AnyEvent::XMPP>
779		1124
780	AnyEvent based XMPP (Jabber protocol) module family.	1125	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1126	Net::XMPP2>.
		1127
		1128	=item L<AnyEvent::IGS>
		1129
		1130	A non-blocking interface to the Internet Go Server protocol (used by
		1131	L<App::IGS>).
781		1132
782	=item L<Net::FCP>	1133	=item L<Net::FCP>
783		1134
784	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1135	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
785	of AnyEvent.	1136	of AnyEvent.
…		…
790		1141
791	=item L<Coro>	1142	=item L<Coro>
792		1143
793	Has special support for AnyEvent via L<Coro::AnyEvent>.	1144	Has special support for AnyEvent via L<Coro::AnyEvent>.
794		1145
795	=item L<AnyEvent::AIO>, L<IO::AIO>
796
797	Truly asynchronous I/O, should be in the toolbox of every event
798	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
799	together.
800
801	=item L<AnyEvent::BDB>, L<BDB>
802
803	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
804	IO::AIO and AnyEvent together.
805
806	=item L<IO::Lambda>
807
808	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
809
810	=back	1146	=back
811		1147
812	=cut	1148	=cut
813		1149
814	package AnyEvent;	1150	package AnyEvent;
815		1151
816	no warnings;	1152	# basically a tuned-down version of common::sense
817	use strict;	1153	sub common_sense {
		1154	# from common:.sense 1.0
		1155	${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
		1156	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1157	$^H |= 0x00000600;
		1158	}
818		1159
		1160	BEGIN { AnyEvent::common_sense }
		1161
819	use Carp;	1162	use Carp ();
820		1163
821	our $VERSION = 4.151;	1164	our $VERSION = '5.26';
822	our $MODEL;	1165	our $MODEL;
823		1166
824	our $AUTOLOAD;	1167	our $AUTOLOAD;
825	our @ISA;	1168	our @ISA;
826		1169
827	our @REGISTRY;	1170	our @REGISTRY;
828		1171
829	our $WIN32;	1172	our $VERBOSE;
830		1173
831	BEGIN {	1174	BEGIN {
832	my $win32 = ! ! ($^O =~ /mswin32/i);	1175	require "AnyEvent/constants.pl";
833	eval "sub WIN32(){ $win32 }";
834	}
835		1176
		1177	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1178
		1179	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1180	if ${^TAINT};
		1181
836	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1182	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1183
		1184	}
		1185
		1186	our $MAX_SIGNAL_LATENCY = 10;
837		1187
838	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1188	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
839		1189
840	{	1190	{
841	my $idx;	1191	my $idx;
…		…
843	for reverse split /\s*,\s*/,	1193	for reverse split /\s*,\s*/,
844	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1194	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
845	}	1195	}
846		1196
847	my @models = (	1197	my @models = (
848	[EV:: => AnyEvent::Impl::EV::],	1198	[EV:: => AnyEvent::Impl::EV:: , 1],
849	[Event:: => AnyEvent::Impl::Event::],
850	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1199	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
851	# everything below here will not be autoprobed	1200	# everything below here will not (normally) be autoprobed
852	# as the pureperl backend should work everywhere	1201	# as the pureperl backend should work everywhere
853	# and is usually faster	1202	# and is usually faster
		1203	[Event:: => AnyEvent::Impl::Event::, 1],
		1204	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1205	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1206	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
854	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1207	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
855	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
856	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
857	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1208	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
858	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1209	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
859	[Wx:: => AnyEvent::Impl::POE::],	1210	[Wx:: => AnyEvent::Impl::POE::],
860	[Prima:: => AnyEvent::Impl::POE::],	1211	[Prima:: => AnyEvent::Impl::POE::],
		1212	# IO::Async is just too broken - we would need workarounds for its
		1213	# byzantine signal and broken child handling, among others.
		1214	# IO::Async is rather hard to detect, as it doesn't have any
		1215	# obvious default class.
		1216	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1217	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1218	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1219	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
861	);	1220	);
862		1221
863	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1222	our %method = map +($_ => 1),
		1223	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
864		1224
865	our @post_detect;	1225	our @post_detect;
866		1226
867	sub post_detect(&) {	1227	sub post_detect(&) {
868	my ($cb) = @_;	1228	my ($cb) = @_;
869		1229
870	if ($MODEL) {
871	$cb->();
872
873	1
874	} else {
875	push @post_detect, $cb;	1230	push @post_detect, $cb;
876		1231
877	defined wantarray	1232	defined wantarray
878	? bless \$cb, "AnyEvent::Util::PostDetect"	1233	? bless \$cb, "AnyEvent::Util::postdetect"
879	: ()	1234	: ()
		1235	}
		1236
		1237	sub AnyEvent::Util::postdetect::DESTROY {
		1238	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1239	}
		1240
		1241	sub detect() {
		1242	# free some memory
		1243	*detect = sub () { $MODEL };
		1244
		1245	local $!; # for good measure
		1246	local $SIG{__DIE__};
		1247
		1248	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1249	my $model = "AnyEvent::Impl::$1";
		1250	if (eval "require $model") {
		1251	$MODEL = $model;
		1252	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1253	} else {
		1254	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1255	}
880	}	1256	}
881	}
882		1257
883	sub AnyEvent::Util::PostDetect::DESTROY {	1258	# check for already loaded models
884	@post_detect = grep $_ != ${$_[0]}, @post_detect;
885	}
886
887	sub detect() {
888	unless ($MODEL) {	1259	unless ($MODEL) {
889	no strict 'refs';	1260	for (@REGISTRY, @models) {
890	local $SIG{__DIE__};	1261	my ($package, $model) = @$_;
891		1262	if (${"$package\::VERSION"} > 0) {
892	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
893	my $model = "AnyEvent::Impl::$1";
894	if (eval "require $model") {	1263	if (eval "require $model") {
895	$MODEL = $model;	1264	$MODEL = $model;
896	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1265	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
897	} else {	1266	last;
898	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1267	}
899	}	1268	}
900	}	1269	}
901		1270
902	# check for already loaded models
903	unless ($MODEL) {	1271	unless ($MODEL) {
		1272	# try to autoload a model
904	for (@REGISTRY, @models) {	1273	for (@REGISTRY, @models) {
905	my ($package, $model) = @$_;	1274	my ($package, $model, $autoload) = @$_;
		1275	if (
		1276	$autoload
		1277	and eval "require $package"
906	if (${"$package\::VERSION"} > 0) {	1278	and ${"$package\::VERSION"} > 0
907	if (eval "require $model") {	1279	and eval "require $model"
		1280	) {
908	$MODEL = $model;	1281	$MODEL = $model;
909	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1282	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
910	last;	1283	last;
911	}
912	}	1284	}
913	}	1285	}
914		1286
915	unless ($MODEL) {
916	# try to load a model
917
918	for (@REGISTRY, @models) {
919	my ($package, $model) = @$_;
920	if (eval "require $package"
921	and ${"$package\::VERSION"} > 0
922	and eval "require $model") {
923	$MODEL = $model;
924	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
925	last;
926	}
927	}
928
929	$MODEL	1287	$MODEL
930	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1288	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
931	}
932	}	1289	}
933
934	unshift @ISA, $MODEL;
935	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
936
937	(shift @post_detect)->() while @post_detect;
938	}	1290	}
		1291
		1292	@models = (); # free probe data
		1293
		1294	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1295	unshift @ISA, $MODEL;
		1296
		1297	# now nuke some methods that are overriden by the backend.
		1298	# SUPER is not allowed.
		1299	for (qw(time signal child idle)) {
		1300	undef &{"AnyEvent::Base::$_"}
		1301	if defined &{"$MODEL\::$_"};
		1302	}
		1303
		1304	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1305
		1306	(shift @post_detect)->() while @post_detect;
		1307
		1308	*post_detect = sub(&) {
		1309	shift->();
		1310
		1311	undef
		1312	};
939		1313
940	$MODEL	1314	$MODEL
941	}	1315	}
942		1316
943	sub AUTOLOAD {	1317	sub AUTOLOAD {
944	(my $func = $AUTOLOAD) =~ s/.*://;	1318	(my $func = $AUTOLOAD) =~ s/.*://;
945		1319
946	$method{$func}	1320	$method{$func}
947	or croak "$func: not a valid method for AnyEvent objects";	1321	or Carp::croak "$func: not a valid AnyEvent class method";
948		1322
949	detect unless $MODEL;	1323	detect;
950		1324
951	my $class = shift;	1325	my $class = shift;
952	$class->$func (@_);	1326	$class->$func (@_);
953	}	1327	}
954		1328
		1329	# utility function to dup a filehandle. this is used by many backends
		1330	# to support binding more than one watcher per filehandle (they usually
		1331	# allow only one watcher per fd, so we dup it to get a different one).
		1332	sub _dupfh($$;$$) {
		1333	my ($poll, $fh, $r, $w) = @_;
		1334
		1335	# cygwin requires the fh mode to be matching, unix doesn't
		1336	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1337
		1338	open my $fh2, $mode, $fh
		1339	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1340
		1341	# we assume CLOEXEC is already set by perl in all important cases
		1342
		1343	($fh2, $rw)
		1344	}
		1345
		1346	=head1 SIMPLIFIED AE API
		1347
		1348	Starting with version 5.0, AnyEvent officially supports a second, much
		1349	simpler, API that is designed to reduce the calling, typing and memory
		1350	overhead by using function call syntax and a fixed number of parameters.
		1351
		1352	See the L<AE> manpage for details.
		1353
		1354	=cut
		1355
		1356	package AE;
		1357
		1358	our $VERSION = $AnyEvent::VERSION;
		1359
		1360	# fall back to the main API by default - backends and AnyEvent::Base
		1361	# implementations can overwrite these.
		1362
		1363	sub io($$$) {
		1364	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1365	}
		1366
		1367	sub timer($$$) {
		1368	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1369	}
		1370
		1371	sub signal($$) {
		1372	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1373	}
		1374
		1375	sub child($$) {
		1376	AnyEvent->child (pid => $_[0], cb => $_[1])
		1377	}
		1378
		1379	sub idle($) {
		1380	AnyEvent->idle (cb => $_[0])
		1381	}
		1382
		1383	sub cv(;&) {
		1384	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1385	}
		1386
		1387	sub now() {
		1388	AnyEvent->now
		1389	}
		1390
		1391	sub now_update() {
		1392	AnyEvent->now_update
		1393	}
		1394
		1395	sub time() {
		1396	AnyEvent->time
		1397	}
		1398
955	package AnyEvent::Base;	1399	package AnyEvent::Base;
956		1400
957	# default implementation for now and time	1401	# default implementations for many methods
958		1402
959	use Time::HiRes ();	1403	sub time {
		1404	eval q{ # poor man's autoloading {}
		1405	# probe for availability of Time::HiRes
		1406	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1407	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1408	*AE::time = \&Time::HiRes::time;
		1409	# if (eval "use POSIX (); (POSIX::times())...
		1410	} else {
		1411	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1412	*AE::time = sub (){ time }; # epic fail
		1413	}
960		1414
961	sub time { Time::HiRes::time }	1415	*time = sub { AE::time }; # different prototypes
962	sub now { Time::HiRes::time }	1416	};
		1417	die if $@;
		1418
		1419	&time
		1420	}
		1421
		1422	*now = \&time;
		1423
		1424	sub now_update { }
963		1425
964	# default implementation for ->condvar	1426	# default implementation for ->condvar
965		1427
966	sub condvar {	1428	sub condvar {
		1429	eval q{ # poor man's autoloading {}
		1430	*condvar = sub {
967	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1431	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1432	};
		1433
		1434	*AE::cv = sub (;&) {
		1435	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1436	};
		1437	};
		1438	die if $@;
		1439
		1440	&condvar
968	}	1441	}
969		1442
970	# default implementation for ->signal	1443	# default implementation for ->signal
971		1444
972	our %SIG_CB;	1445	our $HAVE_ASYNC_INTERRUPT;
		1446
		1447	sub _have_async_interrupt() {
		1448	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1449	&& eval "use Async::Interrupt 1.02 (); 1")
		1450	unless defined $HAVE_ASYNC_INTERRUPT;
		1451
		1452	$HAVE_ASYNC_INTERRUPT
		1453	}
		1454
		1455	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1456	our (%SIG_ASY, %SIG_ASY_W);
		1457	our ($SIG_COUNT, $SIG_TW);
		1458
		1459	# install a dummy wakeup watcher to reduce signal catching latency
		1460	# used by Impls
		1461	sub _sig_add() {
		1462	unless ($SIG_COUNT++) {
		1463	# try to align timer on a full-second boundary, if possible
		1464	my $NOW = AE::now;
		1465
		1466	$SIG_TW = AE::timer
		1467	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1468	$MAX_SIGNAL_LATENCY,
		1469	sub { } # just for the PERL_ASYNC_CHECK
		1470	;
		1471	}
		1472	}
		1473
		1474	sub _sig_del {
		1475	undef $SIG_TW
		1476	unless --$SIG_COUNT;
		1477	}
		1478
		1479	our $_sig_name_init; $_sig_name_init = sub {
		1480	eval q{ # poor man's autoloading {}
		1481	undef $_sig_name_init;
		1482
		1483	if (_have_async_interrupt) {
		1484	*sig2num = \&Async::Interrupt::sig2num;
		1485	*sig2name = \&Async::Interrupt::sig2name;
		1486	} else {
		1487	require Config;
		1488
		1489	my %signame2num;
		1490	@signame2num{ split ' ', $Config::Config{sig_name} }
		1491	= split ' ', $Config::Config{sig_num};
		1492
		1493	my @signum2name;
		1494	@signum2name[values %signame2num] = keys %signame2num;
		1495
		1496	*sig2num = sub($) {
		1497	$_[0] > 0 ? shift : $signame2num{+shift}
		1498	};
		1499	*sig2name = sub ($) {
		1500	$_[0] > 0 ? $signum2name[+shift] : shift
		1501	};
		1502	}
		1503	};
		1504	die if $@;
		1505	};
		1506
		1507	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1508	sub sig2name($) { &$_sig_name_init; &sig2name }
973		1509
974	sub signal {	1510	sub signal {
		1511	eval q{ # poor man's autoloading {}
		1512	# probe for availability of Async::Interrupt
		1513	if (_have_async_interrupt) {
		1514	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1515
		1516	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1517	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1518
		1519	} else {
		1520	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1521
		1522	if (AnyEvent::WIN32) {
		1523	require AnyEvent::Util;
		1524
		1525	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1526	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1527	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1528	} else {
		1529	pipe $SIGPIPE_R, $SIGPIPE_W;
		1530	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1531	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1532
		1533	# not strictly required, as $^F is normally 2, but let's make sure...
		1534	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1535	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1536	}
		1537
		1538	$SIGPIPE_R
		1539	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1540
		1541	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1542	}
		1543
		1544	*signal = $HAVE_ASYNC_INTERRUPT
		1545	? sub {
975	my (undef, %arg) = @_;	1546	my (undef, %arg) = @_;
976		1547
		1548	# async::interrupt
977	my $signal = uc $arg{signal}	1549	my $signal = sig2num $arg{signal};
978	or Carp::croak "required option 'signal' is missing";
979
980	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1550	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1551
		1552	$SIG_ASY{$signal} ||= new Async::Interrupt
		1553	cb => sub { undef $SIG_EV{$signal} },
		1554	signal => $signal,
		1555	pipe => [$SIGPIPE_R->filenos],
		1556	pipe_autodrain => 0,
		1557	;
		1558
		1559	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1560	}
		1561	: sub {
		1562	my (undef, %arg) = @_;
		1563
		1564	# pure perl
		1565	my $signal = sig2name $arg{signal};
		1566	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1567
981	$SIG{$signal} ||= sub {	1568	$SIG{$signal} ||= sub {
		1569	local $!;
		1570	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1571	undef $SIG_EV{$signal};
		1572	};
		1573
		1574	# can't do signal processing without introducing races in pure perl,
		1575	# so limit the signal latency.
		1576	_sig_add;
		1577
		1578	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1579	}
		1580	;
		1581
		1582	*AnyEvent::Base::signal::DESTROY = sub {
		1583	my ($signal, $cb) = @{$_[0]};
		1584
		1585	_sig_del;
		1586
		1587	delete $SIG_CB{$signal}{$cb};
		1588
		1589	$HAVE_ASYNC_INTERRUPT
		1590	? delete $SIG_ASY{$signal}
		1591	: # delete doesn't work with older perls - they then
		1592	# print weird messages, or just unconditionally exit
		1593	# instead of getting the default action.
		1594	undef $SIG{$signal}
		1595	unless keys %{ $SIG_CB{$signal} };
		1596	};
		1597
		1598	*_signal_exec = sub {
		1599	$HAVE_ASYNC_INTERRUPT
		1600	? $SIGPIPE_R->drain
		1601	: sysread $SIGPIPE_R, (my $dummy), 9;
		1602
		1603	while (%SIG_EV) {
		1604	for (keys %SIG_EV) {
		1605	delete $SIG_EV{$_};
982	$_->() for values %{ $SIG_CB{$signal} || {} };	1606	$_->() for values %{ $SIG_CB{$_} || {} };
		1607	}
		1608	}
		1609	};
983	};	1610	};
		1611	die if $@;
984		1612
985	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1613	&signal
986	}
987
988	sub AnyEvent::Base::Signal::DESTROY {
989	my ($signal, $cb) = @{$_[0]};
990
991	delete $SIG_CB{$signal}{$cb};
992
993	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
994	}	1614	}
995		1615
996	# default implementation for ->child	1616	# default implementation for ->child
997		1617
998	our %PID_CB;	1618	our %PID_CB;
999	our $CHLD_W;	1619	our $CHLD_W;
1000	our $CHLD_DELAY_W;	1620	our $CHLD_DELAY_W;
1001	our $PID_IDLE;
1002	our $WNOHANG;	1621	our $WNOHANG;
1003		1622
1004	sub _child_wait {	1623	# used by many Impl's
1005	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1624	sub _emit_childstatus($$) {
		1625	my (undef, $rpid, $rstatus) = @_;
		1626
		1627	$_->($rpid, $rstatus)
1006	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1628	for values %{ $PID_CB{$rpid} || {} },
1007	(values %{ $PID_CB{0} || {} });	1629	values %{ $PID_CB{0} || {} };
1008	}
1009
1010	undef $PID_IDLE;
1011	}
1012
1013	sub _sigchld {
1014	# make sure we deliver these changes "synchronous" with the event loop.
1015	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1016	undef $CHLD_DELAY_W;
1017	&_child_wait;
1018	});
1019	}	1630	}
1020		1631
1021	sub child {	1632	sub child {
		1633	eval q{ # poor man's autoloading {}
		1634	*_sigchld = sub {
		1635	my $pid;
		1636
		1637	AnyEvent->_emit_childstatus ($pid, $?)
		1638	while ($pid = waitpid -1, $WNOHANG) > 0;
		1639	};
		1640
		1641	*child = sub {
1022	my (undef, %arg) = @_;	1642	my (undef, %arg) = @_;
1023		1643
1024	defined (my $pid = $arg{pid} + 0)	1644	defined (my $pid = $arg{pid} + 0)
1025	or Carp::croak "required option 'pid' is missing";	1645	or Carp::croak "required option 'pid' is missing";
1026		1646
1027	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1647	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1028		1648
1029	unless ($WNOHANG) {	1649	# WNOHANG is almost cetrainly 1 everywhere
		1650	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1651	? 1
1030	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1652	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1031	}
1032		1653
1033	unless ($CHLD_W) {	1654	unless ($CHLD_W) {
1034	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1655	$CHLD_W = AE::signal CHLD => \&_sigchld;
1035	# child could be a zombie already, so make at least one round	1656	# child could be a zombie already, so make at least one round
1036	&_sigchld;	1657	&_sigchld;
1037	}	1658	}
1038		1659
1039	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1660	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1040	}	1661	};
1041		1662
1042	sub AnyEvent::Base::Child::DESTROY {	1663	*AnyEvent::Base::child::DESTROY = sub {
1043	my ($pid, $cb) = @{$_[0]};	1664	my ($pid, $cb) = @{$_[0]};
1044		1665
1045	delete $PID_CB{$pid}{$cb};	1666	delete $PID_CB{$pid}{$cb};
1046	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1667	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1047		1668
1048	undef $CHLD_W unless keys %PID_CB;	1669	undef $CHLD_W unless keys %PID_CB;
		1670	};
		1671	};
		1672	die if $@;
		1673
		1674	&child
		1675	}
		1676
		1677	# idle emulation is done by simply using a timer, regardless
		1678	# of whether the process is idle or not, and not letting
		1679	# the callback use more than 50% of the time.
		1680	sub idle {
		1681	eval q{ # poor man's autoloading {}
		1682	*idle = sub {
		1683	my (undef, %arg) = @_;
		1684
		1685	my ($cb, $w, $rcb) = $arg{cb};
		1686
		1687	$rcb = sub {
		1688	if ($cb) {
		1689	$w = _time;
		1690	&$cb;
		1691	$w = _time - $w;
		1692
		1693	# never use more then 50% of the time for the idle watcher,
		1694	# within some limits
		1695	$w = 0.0001 if $w < 0.0001;
		1696	$w = 5 if $w > 5;
		1697
		1698	$w = AE::timer $w, 0, $rcb;
		1699	} else {
		1700	# clean up...
		1701	undef $w;
		1702	undef $rcb;
		1703	}
		1704	};
		1705
		1706	$w = AE::timer 0.05, 0, $rcb;
		1707
		1708	bless \\$cb, "AnyEvent::Base::idle"
		1709	};
		1710
		1711	*AnyEvent::Base::idle::DESTROY = sub {
		1712	undef $${$_[0]};
		1713	};
		1714	};
		1715	die if $@;
		1716
		1717	&idle
1049	}	1718	}
1050		1719
1051	package AnyEvent::CondVar;	1720	package AnyEvent::CondVar;
1052		1721
1053	our @ISA = AnyEvent::CondVar::Base::;	1722	our @ISA = AnyEvent::CondVar::Base::;
1054		1723
1055	package AnyEvent::CondVar::Base;	1724	package AnyEvent::CondVar::Base;
1056		1725
1057	use overload	1726	#use overload
1058	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1727	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1059	fallback => 1;	1728	# fallback => 1;
		1729
		1730	# save 300+ kilobytes by dirtily hardcoding overloading
		1731	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1732	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1733	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1734	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1735
		1736	our $WAITING;
1060		1737
1061	sub _send {	1738	sub _send {
1062	# nop	1739	# nop
1063	}	1740	}
1064		1741
…		…
1077	sub ready {	1754	sub ready {
1078	$_[0]{_ae_sent}	1755	$_[0]{_ae_sent}
1079	}	1756	}
1080		1757
1081	sub _wait {	1758	sub _wait {
		1759	$WAITING
		1760	and !$_[0]{_ae_sent}
		1761	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1762
		1763	local $WAITING = 1;
1082	AnyEvent->one_event while !$_[0]{_ae_sent};	1764	AnyEvent->one_event while !$_[0]{_ae_sent};
1083	}	1765	}
1084		1766
1085	sub recv {	1767	sub recv {
1086	$_[0]->_wait;	1768	$_[0]->_wait;
…		…
1088	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1770	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1089	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1771	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1090	}	1772	}
1091		1773
1092	sub cb {	1774	sub cb {
1093	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1775	my $cv = shift;
		1776
		1777	@_
		1778	and $cv->{_ae_cb} = shift
		1779	and $cv->{_ae_sent}
		1780	and (delete $cv->{_ae_cb})->($cv);
		1781
1094	$_[0]{_ae_cb}	1782	$cv->{_ae_cb}
1095	}	1783	}
1096		1784
1097	sub begin {	1785	sub begin {
1098	++$_[0]{_ae_counter};	1786	++$_[0]{_ae_counter};
1099	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1787	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1105	}	1793	}
1106		1794
1107	# undocumented/compatibility with pre-3.4	1795	# undocumented/compatibility with pre-3.4
1108	*broadcast = \&send;	1796	*broadcast = \&send;
1109	*wait = \&_wait;	1797	*wait = \&_wait;
		1798
		1799	=head1 ERROR AND EXCEPTION HANDLING
		1800
		1801	In general, AnyEvent does not do any error handling - it relies on the
		1802	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1803	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1804	checking of all AnyEvent methods, however, which is highly useful during
		1805	development.
		1806
		1807	As for exception handling (i.e. runtime errors and exceptions thrown while
		1808	executing a callback), this is not only highly event-loop specific, but
		1809	also not in any way wrapped by this module, as this is the job of the main
		1810	program.
		1811
		1812	The pure perl event loop simply re-throws the exception (usually
		1813	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1814	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1815	so on.
		1816
		1817	=head1 ENVIRONMENT VARIABLES
		1818
		1819	The following environment variables are used by this module or its
		1820	submodules.
		1821
		1822	Note that AnyEvent will remove I<all> environment variables starting with
		1823	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1824	enabled.
		1825
		1826	=over 4
		1827
		1828	=item C<PERL_ANYEVENT_VERBOSE>
		1829
		1830	By default, AnyEvent will be completely silent except in fatal
		1831	conditions. You can set this environment variable to make AnyEvent more
		1832	talkative.
		1833
		1834	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1835	conditions, such as not being able to load the event model specified by
		1836	C<PERL_ANYEVENT_MODEL>.
		1837
		1838	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1839	model it chooses.
		1840
		1841	When set to C<8> or higher, then AnyEvent will report extra information on
		1842	which optional modules it loads and how it implements certain features.
		1843
		1844	=item C<PERL_ANYEVENT_STRICT>
		1845
		1846	AnyEvent does not do much argument checking by default, as thorough
		1847	argument checking is very costly. Setting this variable to a true value
		1848	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1849	check the arguments passed to most method calls. If it finds any problems,
		1850	it will croak.
		1851
		1852	In other words, enables "strict" mode.
		1853
		1854	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1855	>>, it is definitely recommended to keep it off in production. Keeping
		1856	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1857	can be very useful, however.
		1858
		1859	=item C<PERL_ANYEVENT_MODEL>
		1860
		1861	This can be used to specify the event model to be used by AnyEvent, before
		1862	auto detection and -probing kicks in. It must be a string consisting
		1863	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1864	and the resulting module name is loaded and if the load was successful,
		1865	used as event model. If it fails to load AnyEvent will proceed with
		1866	auto detection and -probing.
		1867
		1868	This functionality might change in future versions.
		1869
		1870	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1871	could start your program like this:
		1872
		1873	PERL_ANYEVENT_MODEL=Perl perl ...
		1874
		1875	=item C<PERL_ANYEVENT_PROTOCOLS>
		1876
		1877	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1878	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1879	of auto probing).
		1880
		1881	Must be set to a comma-separated list of protocols or address families,
		1882	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1883	used, and preference will be given to protocols mentioned earlier in the
		1884	list.
		1885
		1886	This variable can effectively be used for denial-of-service attacks
		1887	against local programs (e.g. when setuid), although the impact is likely
		1888	small, as the program has to handle conenction and other failures anyways.
		1889
		1890	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1891	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1892	- only support IPv4, never try to resolve or contact IPv6
		1893	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1894	IPv6, but prefer IPv6 over IPv4.
		1895
		1896	=item C<PERL_ANYEVENT_EDNS0>
		1897
		1898	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1899	for DNS. This extension is generally useful to reduce DNS traffic, but
		1900	some (broken) firewalls drop such DNS packets, which is why it is off by
		1901	default.
		1902
		1903	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1904	EDNS0 in its DNS requests.
		1905
		1906	=item C<PERL_ANYEVENT_MAX_FORKS>
		1907
		1908	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1909	will create in parallel.
		1910
		1911	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1912
		1913	The default value for the C<max_outstanding> parameter for the default DNS
		1914	resolver - this is the maximum number of parallel DNS requests that are
		1915	sent to the DNS server.
		1916
		1917	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1918
		1919	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1920	configuration) in the default resolver. When set to the empty string, no
		1921	default config will be used.
		1922
		1923	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1924
		1925	When neither C<ca_file> nor C<ca_path> was specified during
		1926	L<AnyEvent::TLS> context creation, and either of these environment
		1927	variables exist, they will be used to specify CA certificate locations
		1928	instead of a system-dependent default.
		1929
		1930	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1931
		1932	When these are set to C<1>, then the respective modules are not
		1933	loaded. Mostly good for testing AnyEvent itself.
		1934
		1935	=back
1110		1936
1111	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1937	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1112		1938
1113	This is an advanced topic that you do not normally need to use AnyEvent in	1939	This is an advanced topic that you do not normally need to use AnyEvent in
1114	a module. This section is only of use to event loop authors who want to	1940	a module. This section is only of use to event loop authors who want to
…		…
1148		1974
1149	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1975	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1150	condition variables: code blocking while waiting for a condition will	1976	condition variables: code blocking while waiting for a condition will
1151	C<die>. This still works with most modules/usages, and blocking calls must	1977	C<die>. This still works with most modules/usages, and blocking calls must
1152	not be done in an interactive application, so it makes sense.	1978	not be done in an interactive application, so it makes sense.
1153
1154	=head1 ENVIRONMENT VARIABLES
1155
1156	The following environment variables are used by this module:
1157
1158	=over 4
1159
1160	=item C<PERL_ANYEVENT_VERBOSE>
1161
1162	By default, AnyEvent will be completely silent except in fatal
1163	conditions. You can set this environment variable to make AnyEvent more
1164	talkative.
1165
1166	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1167	conditions, such as not being able to load the event model specified by
1168	C<PERL_ANYEVENT_MODEL>.
1169
1170	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1171	model it chooses.
1172
1173	=item C<PERL_ANYEVENT_MODEL>
1174
1175	This can be used to specify the event model to be used by AnyEvent, before
1176	auto detection and -probing kicks in. It must be a string consisting
1177	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1178	and the resulting module name is loaded and if the load was successful,
1179	used as event model. If it fails to load AnyEvent will proceed with
1180	auto detection and -probing.
1181
1182	This functionality might change in future versions.
1183
1184	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1185	could start your program like this:
1186
1187	PERL_ANYEVENT_MODEL=Perl perl ...
1188
1189	=item C<PERL_ANYEVENT_PROTOCOLS>
1190
1191	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1192	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1193	of auto probing).
1194
1195	Must be set to a comma-separated list of protocols or address families,
1196	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1197	used, and preference will be given to protocols mentioned earlier in the
1198	list.
1199
1200	This variable can effectively be used for denial-of-service attacks
1201	against local programs (e.g. when setuid), although the impact is likely
1202	small, as the program has to handle connection errors already-
1203
1204	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1205	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1206	- only support IPv4, never try to resolve or contact IPv6
1207	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1208	IPv6, but prefer IPv6 over IPv4.
1209
1210	=item C<PERL_ANYEVENT_EDNS0>
1211
1212	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1213	for DNS. This extension is generally useful to reduce DNS traffic, but
1214	some (broken) firewalls drop such DNS packets, which is why it is off by
1215	default.
1216
1217	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1218	EDNS0 in its DNS requests.
1219
1220	=item C<PERL_ANYEVENT_MAX_FORKS>
1221
1222	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1223	will create in parallel.
1224
1225	=back
1226		1979
1227	=head1 EXAMPLE PROGRAM	1980	=head1 EXAMPLE PROGRAM
1228		1981
1229	The following program uses an I/O watcher to read data from STDIN, a timer	1982	The following program uses an I/O watcher to read data from STDIN, a timer
1230	to display a message once per second, and a condition variable to quit the	1983	to display a message once per second, and a condition variable to quit the
…		…
1243	warn "read: $input\n"; # output what has been read	1996	warn "read: $input\n"; # output what has been read
1244	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1997	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1245	},	1998	},
1246	);	1999	);
1247		2000
1248	my $time_watcher; # can only be used once
1249
1250	sub new_timer {
1251	$timer = AnyEvent->timer (after => 1, cb => sub {	2001	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1252	warn "timeout\n"; # print 'timeout' about every second	2002	warn "timeout\n"; # print 'timeout' at most every second
1253	&new_timer; # and restart the time
1254	});	2003	});
1255	}
1256
1257	new_timer; # create first timer
1258		2004
1259	$cv->recv; # wait until user enters /^q/i	2005	$cv->recv; # wait until user enters /^q/i
1260		2006
1261	=head1 REAL-WORLD EXAMPLE	2007	=head1 REAL-WORLD EXAMPLE
1262		2008
…		…
1335		2081
1336	The actual code goes further and collects all errors (C<die>s, exceptions)	2082	The actual code goes further and collects all errors (C<die>s, exceptions)
1337	that occurred during request processing. The C<result> method detects	2083	that occurred during request processing. The C<result> method detects
1338	whether an exception as thrown (it is stored inside the $txn object)	2084	whether an exception as thrown (it is stored inside the $txn object)
1339	and just throws the exception, which means connection errors and other	2085	and just throws the exception, which means connection errors and other
1340	problems get reported tot he code that tries to use the result, not in a	2086	problems get reported to the code that tries to use the result, not in a
1341	random callback.	2087	random callback.
1342		2088
1343	All of this enables the following usage styles:	2089	All of this enables the following usage styles:
1344		2090
1345	1. Blocking:	2091	1. Blocking:
…		…
1393	through AnyEvent. The benchmark creates a lot of timers (with a zero	2139	through AnyEvent. The benchmark creates a lot of timers (with a zero
1394	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2140	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1395	which it is), lets them fire exactly once and destroys them again.	2141	which it is), lets them fire exactly once and destroys them again.
1396		2142
1397	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2143	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1398	distribution.	2144	distribution. It uses the L<AE> interface, which makes a real difference
		2145	for the EV and Perl backends only.
1399		2146
1400	=head3 Explanation of the columns	2147	=head3 Explanation of the columns
1401		2148
1402	I<watcher> is the number of event watchers created/destroyed. Since	2149	I<watcher> is the number of event watchers created/destroyed. Since
1403	different event models feature vastly different performances, each event	2150	different event models feature vastly different performances, each event
…		…
1424	watcher.	2171	watcher.
1425		2172
1426	=head3 Results	2173	=head3 Results
1427		2174
1428	name watchers bytes create invoke destroy comment	2175	name watchers bytes create invoke destroy comment
1429	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2176	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1430	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2177	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1431	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2178	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1432	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2179	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1433	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2180	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1434	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2181	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2182	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2183	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1435	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2184	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1436	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2185	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1437	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2186	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1438	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2187	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1439		2188
1440	=head3 Discussion	2189	=head3 Discussion
1441		2190
1442	The benchmark does I<not> measure scalability of the event loop very	2191	The benchmark does I<not> measure scalability of the event loop very
1443	well. For example, a select-based event loop (such as the pure perl one)	2192	well. For example, a select-based event loop (such as the pure perl one)
…		…
1455	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2204	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1456	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2205	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1457	cycles with POE.	2206	cycles with POE.
1458		2207
1459	C<EV> is the sole leader regarding speed and memory use, which are both	2208	C<EV> is the sole leader regarding speed and memory use, which are both
1460	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2209	maximal/minimal, respectively. When using the L<AE> API there is zero
		2210	overhead (when going through the AnyEvent API create is about 5-6 times
		2211	slower, with other times being equal, so still uses far less memory than
1461	far less memory than any other event loop and is still faster than Event	2212	any other event loop and is still faster than Event natively).
1462	natively.
1463		2213
1464	The pure perl implementation is hit in a few sweet spots (both the	2214	The pure perl implementation is hit in a few sweet spots (both the
1465	constant timeout and the use of a single fd hit optimisations in the perl	2215	constant timeout and the use of a single fd hit optimisations in the perl
1466	interpreter and the backend itself). Nevertheless this shows that it	2216	interpreter and the backend itself). Nevertheless this shows that it
1467	adds very little overhead in itself. Like any select-based backend its	2217	adds very little overhead in itself. Like any select-based backend its
1468	performance becomes really bad with lots of file descriptors (and few of	2218	performance becomes really bad with lots of file descriptors (and few of
1469	them active), of course, but this was not subject of this benchmark.	2219	them active), of course, but this was not subject of this benchmark.
1470		2220
1471	The C<Event> module has a relatively high setup and callback invocation	2221	The C<Event> module has a relatively high setup and callback invocation
1472	cost, but overall scores in on the third place.	2222	cost, but overall scores in on the third place.
		2223
		2224	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2225	when using its pure perl backend.
1473		2226
1474	C<Glib>'s memory usage is quite a bit higher, but it features a	2227	C<Glib>'s memory usage is quite a bit higher, but it features a
1475	faster callback invocation and overall ends up in the same class as	2228	faster callback invocation and overall ends up in the same class as
1476	C<Event>. However, Glib scales extremely badly, doubling the number of	2229	C<Event>. However, Glib scales extremely badly, doubling the number of
1477	watchers increases the processing time by more than a factor of four,	2230	watchers increases the processing time by more than a factor of four,
…		…
1538	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2291	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1539	(1%) are active. This mirrors the activity of large servers with many	2292	(1%) are active. This mirrors the activity of large servers with many
1540	connections, most of which are idle at any one point in time.	2293	connections, most of which are idle at any one point in time.
1541		2294
1542	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2295	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1543	distribution.	2296	distribution. It uses the L<AE> interface, which makes a real difference
		2297	for the EV and Perl backends only.
1544		2298
1545	=head3 Explanation of the columns	2299	=head3 Explanation of the columns
1546		2300
1547	I<sockets> is the number of sockets, and twice the number of "servers" (as	2301	I<sockets> is the number of sockets, and twice the number of "servers" (as
1548	each server has a read and write socket end).	2302	each server has a read and write socket end).
…		…
1555	it to another server. This includes deleting the old timeout and creating	2309	it to another server. This includes deleting the old timeout and creating
1556	a new one that moves the timeout into the future.	2310	a new one that moves the timeout into the future.
1557		2311
1558	=head3 Results	2312	=head3 Results
1559		2313
1560	name sockets create request	2314	name sockets create request
1561	EV 20000 69.01 11.16	2315	EV 20000 62.66 7.99
1562	Perl 20000 73.32 35.87	2316	Perl 20000 68.32 32.64
1563	Event 20000 212.62 257.32	2317	IOAsync 20000 174.06 101.15 epoll
1564	Glib 20000 651.16 1896.30	2318	IOAsync 20000 174.67 610.84 poll
		2319	Event 20000 202.69 242.91
		2320	Glib 20000 557.01 1689.52
1565	POE 20000 349.67 12317.24 uses POE::Loop::Event	2321	POE 20000 341.54 12086.32 uses POE::Loop::Event
1566		2322
1567	=head3 Discussion	2323	=head3 Discussion
1568		2324
1569	This benchmark I<does> measure scalability and overall performance of the	2325	This benchmark I<does> measure scalability and overall performance of the
1570	particular event loop.	2326	particular event loop.
…		…
1572	EV is again fastest. Since it is using epoll on my system, the setup time	2328	EV is again fastest. Since it is using epoll on my system, the setup time
1573	is relatively high, though.	2329	is relatively high, though.
1574		2330
1575	Perl surprisingly comes second. It is much faster than the C-based event	2331	Perl surprisingly comes second. It is much faster than the C-based event
1576	loops Event and Glib.	2332	loops Event and Glib.
		2333
		2334	IO::Async performs very well when using its epoll backend, and still quite
		2335	good compared to Glib when using its pure perl backend.
1577		2336
1578	Event suffers from high setup time as well (look at its code and you will	2337	Event suffers from high setup time as well (look at its code and you will
1579	understand why). Callback invocation also has a high overhead compared to	2338	understand why). Callback invocation also has a high overhead compared to
1580	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2339	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1581	uses select or poll in basically all documented configurations.	2340	uses select or poll in basically all documented configurations.
…		…
1644	=item * C-based event loops perform very well with small number of	2403	=item * C-based event loops perform very well with small number of
1645	watchers, as the management overhead dominates.	2404	watchers, as the management overhead dominates.
1646		2405
1647	=back	2406	=back
1648		2407
		2408	=head2 THE IO::Lambda BENCHMARK
		2409
		2410	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2411	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2412	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2413	shouldn't come as a surprise to anybody). As such, the benchmark is
		2414	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2415	very optimal. But how would AnyEvent compare when used without the extra
		2416	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2417
		2418	The benchmark itself creates an echo-server, and then, for 500 times,
		2419	connects to the echo server, sends a line, waits for the reply, and then
		2420	creates the next connection. This is a rather bad benchmark, as it doesn't
		2421	test the efficiency of the framework or much non-blocking I/O, but it is a
		2422	benchmark nevertheless.
		2423
		2424	name runtime
		2425	Lambda/select 0.330 sec
		2426	+ optimized 0.122 sec
		2427	Lambda/AnyEvent 0.327 sec
		2428	+ optimized 0.138 sec
		2429	Raw sockets/select 0.077 sec
		2430	POE/select, components 0.662 sec
		2431	POE/select, raw sockets 0.226 sec
		2432	POE/select, optimized 0.404 sec
		2433
		2434	AnyEvent/select/nb 0.085 sec
		2435	AnyEvent/EV/nb 0.068 sec
		2436	+state machine 0.134 sec
		2437
		2438	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2439	benchmarks actually make blocking connects and use 100% blocking I/O,
		2440	defeating the purpose of an event-based solution. All of the newly
		2441	written AnyEvent benchmarks use 100% non-blocking connects (using
		2442	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2443	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2444	generally require a lot more bookkeeping and event handling than blocking
		2445	connects (which involve a single syscall only).
		2446
		2447	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2448	offers similar expressive power as POE and IO::Lambda, using conventional
		2449	Perl syntax. This means that both the echo server and the client are 100%
		2450	non-blocking, further placing it at a disadvantage.
		2451
		2452	As you can see, the AnyEvent + EV combination even beats the
		2453	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2454	backend easily beats IO::Lambda and POE.
		2455
		2456	And even the 100% non-blocking version written using the high-level (and
		2457	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2458	higher level ("unoptimised") abstractions by a large margin, even though
		2459	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2460
		2461	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2462	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2463	part of the IO::Lambda distribution and were used without any changes.
		2464
		2465
		2466	=head1 SIGNALS
		2467
		2468	AnyEvent currently installs handlers for these signals:
		2469
		2470	=over 4
		2471
		2472	=item SIGCHLD
		2473
		2474	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2475	emulation for event loops that do not support them natively. Also, some
		2476	event loops install a similar handler.
		2477
		2478	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2479	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2480
		2481	=item SIGPIPE
		2482
		2483	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2484	when AnyEvent gets loaded.
		2485
		2486	The rationale for this is that AnyEvent users usually do not really depend
		2487	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2488	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2489	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2490	some random socket.
		2491
		2492	The rationale for installing a no-op handler as opposed to ignoring it is
		2493	that this way, the handler will be restored to defaults on exec.
		2494
		2495	Feel free to install your own handler, or reset it to defaults.
		2496
		2497	=back
		2498
		2499	=cut
		2500
		2501	undef $SIG{CHLD}
		2502	if $SIG{CHLD} eq 'IGNORE';
		2503
		2504	$SIG{PIPE} = sub { }
		2505	unless defined $SIG{PIPE};
		2506
		2507	=head1 RECOMMENDED/OPTIONAL MODULES
		2508
		2509	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2510	it's built-in modules) are required to use it.
		2511
		2512	That does not mean that AnyEvent won't take advantage of some additional
		2513	modules if they are installed.
		2514
		2515	This section explains which additional modules will be used, and how they
		2516	affect AnyEvent's operation.
		2517
		2518	=over 4
		2519
		2520	=item L<Async::Interrupt>
		2521
		2522	This slightly arcane module is used to implement fast signal handling: To
		2523	my knowledge, there is no way to do completely race-free and quick
		2524	signal handling in pure perl. To ensure that signals still get
		2525	delivered, AnyEvent will start an interval timer to wake up perl (and
		2526	catch the signals) with some delay (default is 10 seconds, look for
		2527	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2528
		2529	If this module is available, then it will be used to implement signal
		2530	catching, which means that signals will not be delayed, and the event loop
		2531	will not be interrupted regularly, which is more efficient (and good for
		2532	battery life on laptops).
		2533
		2534	This affects not just the pure-perl event loop, but also other event loops
		2535	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2536
		2537	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2538	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2539	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2540	does nothing for those backends.
		2541
		2542	=item L<EV>
		2543
		2544	This module isn't really "optional", as it is simply one of the backend
		2545	event loops that AnyEvent can use. However, it is simply the best event
		2546	loop available in terms of features, speed and stability: It supports
		2547	the AnyEvent API optimally, implements all the watcher types in XS, does
		2548	automatic timer adjustments even when no monotonic clock is available,
		2549	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2550	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2551	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2552
		2553	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2554	then this module will do nothing for you.
		2555
		2556	=item L<Guard>
		2557
		2558	The guard module, when used, will be used to implement
		2559	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2560	lot less memory), but otherwise doesn't affect guard operation much. It is
		2561	purely used for performance.
		2562
		2563	=item L<JSON> and L<JSON::XS>
		2564
		2565	One of these modules is required when you want to read or write JSON data
		2566	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2567	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2568
		2569	=item L<Net::SSLeay>
		2570
		2571	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2572	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2573	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2574
		2575	=item L<Time::HiRes>
		2576
		2577	This module is part of perl since release 5.008. It will be used when the
		2578	chosen event library does not come with a timing source on it's own. The
		2579	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2580	try to use a monotonic clock for timing stability.
		2581
		2582	=back
		2583
1649		2584
1650	=head1 FORK	2585	=head1 FORK
1651		2586
1652	Most event libraries are not fork-safe. The ones who are usually are	2587	Most event libraries are not fork-safe. The ones who are usually are
1653	because they rely on inefficient but fork-safe C<select> or C<poll>	2588	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1654	calls. Only L<EV> is fully fork-aware.	2589	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2590	are usually badly thought-out hacks that are incompatible with fork in
		2591	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2592	continue event-processing in both parent and child (or both, if you know
		2593	what you are doing).
		2594
		2595	This means that, in general, you cannot fork and do event processing in
		2596	the child if the event library was initialised before the fork (which
		2597	usually happens when the first AnyEvent watcher is created, or the library
		2598	is loaded).
1655		2599
1656	If you have to fork, you must either do so I<before> creating your first	2600	If you have to fork, you must either do so I<before> creating your first
1657	watcher OR you must not use AnyEvent at all in the child.	2601	watcher OR you must not use AnyEvent at all in the child OR you must do
		2602	something completely out of the scope of AnyEvent.
		2603
		2604	The problem of doing event processing in the parent I<and> the child
		2605	is much more complicated: even for backends that I<are> fork-aware or
		2606	fork-safe, their behaviour is not usually what you want: fork clones all
		2607	watchers, that means all timers, I/O watchers etc. are active in both
		2608	parent and child, which is almost never what you want. USing C<exec>
		2609	to start worker children from some kind of manage rprocess is usually
		2610	preferred, because it is much easier and cleaner, at the expense of having
		2611	to have another binary.
1658		2612
1659		2613
1660	=head1 SECURITY CONSIDERATIONS	2614	=head1 SECURITY CONSIDERATIONS
1661		2615
1662	AnyEvent can be forced to load any event model via	2616	AnyEvent can be forced to load any event model via
…		…
1673		2627
1674	use AnyEvent;	2628	use AnyEvent;
1675		2629
1676	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2630	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1677	be used to probe what backend is used and gain other information (which is	2631	be used to probe what backend is used and gain other information (which is
1678	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2632	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2633	$ENV{PERL_ANYEVENT_STRICT}.
		2634
		2635	Note that AnyEvent will remove I<all> environment variables starting with
		2636	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2637	enabled.
1679		2638
1680		2639
1681	=head1 BUGS	2640	=head1 BUGS
1682		2641
1683	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2642	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1684	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2643	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1685	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2644	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1686	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2645	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1687	pronounced).	2646	pronounced).
1688		2647
1689		2648
1690	=head1 SEE ALSO	2649	=head1 SEE ALSO
1691		2650
…		…
1695	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2654	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1696		2655
1697	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2656	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1698	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2657	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1699	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2658	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1700	L<AnyEvent::Impl::POE>.	2659	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1701		2660
1702	Non-blocking file handles, sockets, TCP clients and	2661	Non-blocking file handles, sockets, TCP clients and
1703	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2662	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1704		2663
1705	Asynchronous DNS: L<AnyEvent::DNS>.	2664	Asynchronous DNS: L<AnyEvent::DNS>.
1706		2665
1707	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2666	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2667	L<Coro::Event>,
1708		2668
1709	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2669	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2670	L<AnyEvent::HTTP>.
1710		2671
1711		2672
1712	=head1 AUTHOR	2673	=head1 AUTHOR
1713		2674
1714	Marc Lehmann <schmorp@schmorp.de>	2675	Marc Lehmann <schmorp@schmorp.de>

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