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Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs.
Revision 1.264 by root, Wed Jul 29 12:42:09 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		53
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		55
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
27		58
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
30		61
31	First and foremost, I<AnyEvent is not an event model> itself, it only	62	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	63	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	65	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	66	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
37		69
38	The goal of AnyEvent is to offer module authors the ability to do event	70	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	71	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
42	model you use.	74	model you use.
43		75
44	For modules like POE or IO::Async (which is a total misnomer as it is	76	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	77	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	78	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	80	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	81	module are I<also> forced to use the same event loop you use.
50		82
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	85	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	86	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	87	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	88	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	89	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
59		91
60	In addition to being free of having to use I<the one and only true event	92	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	93	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	94	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	95	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
124	is in control).	156	is in control).
125		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
126	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	166	to it).
129		167
130	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	171	example), or need to refer to their watcher object in other ways.
134		172
135	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
136		174
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
139	undef $w;	177	undef $w;
140	});	178	});
141		179
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	180	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
144	declared.	182	declared.
145		183
146	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
147		185
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
150		188
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
152	for events. C<poll> must be a string that is either C<r> or C<w>,	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
154	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		200
157	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
160		204
…		…
164		208
165	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	210	always use non-blocking calls when reading/writing from/to your file
167	handles.	211	handles.
168		212
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	213	Example: wait for readability of STDIN, then read a line and disable the
		214	watcher.
		215
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	218	warn "read: $input\n";
175	undef $w;	219	undef $w;
176	});	220	});
…		…
186		230
187	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
190		234
191	The timer callback will be invoked at most once: if you want a repeating	235	The callback will normally be invoked once only. If you specify another
192	timer you have to create a new watcher (this is a limitation by both Tk	236	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
194		240
195	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
196		244
197	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	248	warn "timeout\n";
200	});	249	});
201		250
202	# to cancel the timer:	251	# to cancel the timer:
203	undef $w;	252	undef $w;
204		253
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	254	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		255
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
213	};	258	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		259
218	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
219		261
220	There are two ways to handle timers: based on real time (relative, "fire	262	There are two ways to handle timers: based on real time (relative, "fire
221	in 10 seconds") and based on wallclock time (absolute, "fire at 12	263	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
243		285
244	This returns the "current wallclock time" as a fractional number of	286	This returns the "current wallclock time" as a fractional number of
245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>	287	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
246	return, and the result is guaranteed to be compatible with those).	288	return, and the result is guaranteed to be compatible with those).
247		289
248	It progresses independently of any event loop processing.	290	It progresses independently of any event loop processing, i.e. each call
249		291	will check the system clock, which usually gets updated frequently.
250	In almost all cases (in all cases if you don't care), this is the function
251	to call when you want to know the current time.
252		292
253	=item AnyEvent->now	293	=item AnyEvent->now
254		294
255	This also returns the "current wallclock time", but unlike C<time>, above,	295	This also returns the "current wallclock time", but unlike C<time>, above,
256	this value might change only once per event loop iteration, depending on	296	this value might change only once per event loop iteration, depending on
257	the event loop (most return the same time as C<time>, above). This is the	297	the event loop (most return the same time as C<time>, above). This is the
258	time that AnyEvent timers get scheduled against.	298	time that AnyEvent's timers get scheduled against.
		299
		300	I<In almost all cases (in all cases if you don't care), this is the
		301	function to call when you want to know the current time.>
		302
		303	This function is also often faster then C<< AnyEvent->time >>, and
		304	thus the preferred method if you want some timestamp (for example,
		305	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		306
		307	The rest of this section is only of relevance if you try to be very exact
		308	with your timing, you can skip it without bad conscience.
259		309
260	For a practical example of when these times differ, consider L<Event::Lib>	310	For a practical example of when these times differ, consider L<Event::Lib>
261	and L<EV> and the following set-up:	311	and L<EV> and the following set-up:
262		312
263	The event loop is running and has just invoked one of your callback at	313	The event loop is running and has just invoked one of your callback at
…		…
268		318
269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will	319	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
270	both return C<501>, because that is the current time, and the timer will	320	both return C<501>, because that is the current time, and the timer will
271	be scheduled to fire at time=504 (C<501> + C<3>).	321	be scheduled to fire at time=504 (C<501> + C<3>).
272		322
273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current	323	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the	324	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
275	last event processing phase started. With L<EV>, your timer gets scheduled	325	last event processing phase started. With L<EV>, your timer gets scheduled
276	to run at time=503 (C<500> + C<3>).	326	to run at time=503 (C<500> + C<3>).
277		327
278	In one sense, L<Event::Lib> is more exact, as it uses the current time	328	In one sense, L<Event::Lib> is more exact, as it uses the current time
279	regardless of any delays introduced by event processing. However, most	329	regardless of any delays introduced by event processing. However, most
280	callbacks do not expect large delays in processing, so this causes a	330	callbacks do not expect large delays in processing, so this causes a
281	higher drift (and a lot more syscalls to get the current time).	331	higher drift (and a lot more system calls to get the current time).
282		332
283	In another sense, L<EV> is more exact, as your timer will be scheduled at	333	In another sense, L<EV> is more exact, as your timer will be scheduled at
284	the same time, regardless of how long event processing actually took.	334	the same time, regardless of how long event processing actually took.
285		335
286	In either case, if you care (and in most cases, you don't), then you	336	In either case, if you care (and in most cases, you don't), then you
287	can get whatever behaviour you want with any event loop, by taking the	337	can get whatever behaviour you want with any event loop, by taking the
288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
289	account.	339	account.
290		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
291	=back	356	=back
292		357
293	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
294		359
295	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
296	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
297	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
298		363
299	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
300	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
301	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
302		367
…		…
304	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
305	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
306	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
307		372
308	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
309	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
310		376
311	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
312	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
313		380
314	Example: exit on SIGINT	381	Example: exit on SIGINT
315		382
316	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
317		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
318	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
319		402
320	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
321		404
322	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (one some backends,
323	watches for any child process exit). The watcher will trigger as often	406	using C<0> watches for any child process exit, on others this will
324	as status change for the child are received. This works by installing a	407	croak). The watcher will be triggered only when the child process has
325	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	finished and an exit status is available, not on any trace events
326	and exit status (as returned by waitpid), so unlike other watcher types,	409	(stopped/continued).
327	you I<can> rely on child watcher callback arguments.	410
		411	The callback will be called with the pid and exit status (as returned by
		412	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		413	callback arguments.
		414
		415	This watcher type works by installing a signal handler for C<SIGCHLD>,
		416	and since it cannot be shared, nothing else should use SIGCHLD or reap
		417	random child processes (waiting for specific child processes, e.g. inside
		418	C<system>, is just fine).
328		419
329	There is a slight catch to child watchers, however: you usually start them	420	There is a slight catch to child watchers, however: you usually start them
330	I<after> the child process was created, and this means the process could	421	I<after> the child process was created, and this means the process could
331	have exited already (and no SIGCHLD will be sent anymore).	422	have exited already (and no SIGCHLD will be sent anymore).
332		423
333	Not all event models handle this correctly (POE doesn't), but even for	424	Not all event models handle this correctly (neither POE nor IO::Async do,
		425	see their AnyEvent::Impl manpages for details), but even for event models
334	event models that I<do> handle this correctly, they usually need to be	426	that I<do> handle this correctly, they usually need to be loaded before
335	loaded before the process exits (i.e. before you fork in the first place).	427	the process exits (i.e. before you fork in the first place). AnyEvent's
		428	pure perl event loop handles all cases correctly regardless of when you
		429	start the watcher.
336		430
337	This means you cannot create a child watcher as the very first thing in an	431	This means you cannot create a child watcher as the very first
338	AnyEvent program, you I<have> to create at least one watcher before you	432	thing in an AnyEvent program, you I<have> to create at least one
339	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	433	watcher before you C<fork> the child (alternatively, you can call
		434	C<AnyEvent::detect>).
		435
		436	As most event loops do not support waiting for child events, they will be
		437	emulated by AnyEvent in most cases, in which the latency and race problems
		438	mentioned in the description of signal watchers apply.
340		439
341	Example: fork a process and wait for it	440	Example: fork a process and wait for it
342		441
343	my $done = AnyEvent->condvar;	442	my $done = AnyEvent->condvar;
344		443
345	my $pid = fork or exit 5;	444	my $pid = fork or exit 5;
346		445
347	my $w = AnyEvent->child (	446	my $w = AnyEvent->child (
348	pid => $pid,	447	pid => $pid,
349	cb => sub {	448	cb => sub {
350	my ($pid, $status) = @_;	449	my ($pid, $status) = @_;
351	warn "pid $pid exited with status $status";	450	warn "pid $pid exited with status $status";
352	$done->send;	451	$done->send;
353	},	452	},
354	);	453	);
355		454
356	# do something else, then wait for process exit	455	# do something else, then wait for process exit
357	$done->recv;	456	$done->recv;
		457
		458	=head2 IDLE WATCHERS
		459
		460	Sometimes there is a need to do something, but it is not so important
		461	to do it instantly, but only when there is nothing better to do. This
		462	"nothing better to do" is usually defined to be "no other events need
		463	attention by the event loop".
		464
		465	Idle watchers ideally get invoked when the event loop has nothing
		466	better to do, just before it would block the process to wait for new
		467	events. Instead of blocking, the idle watcher is invoked.
		468
		469	Most event loops unfortunately do not really support idle watchers (only
		470	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		471	will simply call the callback "from time to time".
		472
		473	Example: read lines from STDIN, but only process them when the
		474	program is otherwise idle:
		475
		476	my @lines; # read data
		477	my $idle_w;
		478	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		479	push @lines, scalar <STDIN>;
		480
		481	# start an idle watcher, if not already done
		482	$idle_w ||= AnyEvent->idle (cb => sub {
		483	# handle only one line, when there are lines left
		484	if (my $line = shift @lines) {
		485	print "handled when idle: $line";
		486	} else {
		487	# otherwise disable the idle watcher again
		488	undef $idle_w;
		489	}
		490	});
		491	});
358		492
359	=head2 CONDITION VARIABLES	493	=head2 CONDITION VARIABLES
360		494
361	If you are familiar with some event loops you will know that all of them	495	If you are familiar with some event loops you will know that all of them
362	require you to run some blocking "loop", "run" or similar function that	496	require you to run some blocking "loop", "run" or similar function that
363	will actively watch for new events and call your callbacks.	497	will actively watch for new events and call your callbacks.
364		498
365	AnyEvent is different, it expects somebody else to run the event loop and	499	AnyEvent is slightly different: it expects somebody else to run the event
366	will only block when necessary (usually when told by the user).	500	loop and will only block when necessary (usually when told by the user).
367		501
368	The instrument to do that is called a "condition variable", so called	502	The instrument to do that is called a "condition variable", so called
369	because they represent a condition that must become true.	503	because they represent a condition that must become true.
		504
		505	Now is probably a good time to look at the examples further below.
370		506
371	Condition variables can be created by calling the C<< AnyEvent->condvar	507	Condition variables can be created by calling the C<< AnyEvent->condvar
372	>> method, usually without arguments. The only argument pair allowed is	508	>> method, usually without arguments. The only argument pair allowed is
373	C<cb>, which specifies a callback to be called when the condition variable	509	C<cb>, which specifies a callback to be called when the condition variable
374	becomes true.	510	becomes true, with the condition variable as the first argument (but not
		511	the results).
375		512
376	After creation, the condition variable is "false" until it becomes "true"	513	After creation, the condition variable is "false" until it becomes "true"
377	by calling the C<send> method (or calling the condition variable as if it	514	by calling the C<send> method (or calling the condition variable as if it
378	were a callback, read about the caveats in the description for the C<<	515	were a callback, read about the caveats in the description for the C<<
379	->send >> method).	516	->send >> method).
…		…
381	Condition variables are similar to callbacks, except that you can	518	Condition variables are similar to callbacks, except that you can
382	optionally wait for them. They can also be called merge points - points	519	optionally wait for them. They can also be called merge points - points
383	in time where multiple outstanding events have been processed. And yet	520	in time where multiple outstanding events have been processed. And yet
384	another way to call them is transactions - each condition variable can be	521	another way to call them is transactions - each condition variable can be
385	used to represent a transaction, which finishes at some point and delivers	522	used to represent a transaction, which finishes at some point and delivers
386	a result.	523	a result. And yet some people know them as "futures" - a promise to
		524	compute/deliver something that you can wait for.
387		525
388	Condition variables are very useful to signal that something has finished,	526	Condition variables are very useful to signal that something has finished,
389	for example, if you write a module that does asynchronous http requests,	527	for example, if you write a module that does asynchronous http requests,
390	then a condition variable would be the ideal candidate to signal the	528	then a condition variable would be the ideal candidate to signal the
391	availability of results. The user can either act when the callback is	529	availability of results. The user can either act when the callback is
…		…
425	after => 1,	563	after => 1,
426	cb => sub { $result_ready->send },	564	cb => sub { $result_ready->send },
427	);	565	);
428		566
429	# this "blocks" (while handling events) till the callback	567	# this "blocks" (while handling events) till the callback
430	# calls send	568	# calls -<send
431	$result_ready->recv;	569	$result_ready->recv;
432		570
433	Example: wait for a timer, but take advantage of the fact that	571	Example: wait for a timer, but take advantage of the fact that condition
434	condition variables are also code references.	572	variables are also callable directly.
435		573
436	my $done = AnyEvent->condvar;	574	my $done = AnyEvent->condvar;
437	my $delay = AnyEvent->timer (after => 5, cb => $done);	575	my $delay = AnyEvent->timer (after => 5, cb => $done);
438	$done->recv;	576	$done->recv;
		577
		578	Example: Imagine an API that returns a condvar and doesn't support
		579	callbacks. This is how you make a synchronous call, for example from
		580	the main program:
		581
		582	use AnyEvent::CouchDB;
		583
		584	...
		585
		586	my @info = $couchdb->info->recv;
		587
		588	And this is how you would just set a callback to be called whenever the
		589	results are available:
		590
		591	$couchdb->info->cb (sub {
		592	my @info = $_[0]->recv;
		593	});
439		594
440	=head3 METHODS FOR PRODUCERS	595	=head3 METHODS FOR PRODUCERS
441		596
442	These methods should only be used by the producing side, i.e. the	597	These methods should only be used by the producing side, i.e. the
443	code/module that eventually sends the signal. Note that it is also	598	code/module that eventually sends the signal. Note that it is also
…		…
456	immediately from within send.	611	immediately from within send.
457		612
458	Any arguments passed to the C<send> call will be returned by all	613	Any arguments passed to the C<send> call will be returned by all
459	future C<< ->recv >> calls.	614	future C<< ->recv >> calls.
460		615
461	Condition variables are overloaded so one can call them directly	616	Condition variables are overloaded so one can call them directly (as if
462	(as a code reference). Calling them directly is the same as calling	617	they were a code reference). Calling them directly is the same as calling
463	C<send>. Note, however, that many C-based event loops do not handle	618	C<send>.
464	overloading, so as tempting as it may be, passing a condition variable
465	instead of a callback does not work. Both the pure perl and EV loops
466	support overloading, however, as well as all functions that use perl to
467	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
468	example).
469		619
470	=item $cv->croak ($error)	620	=item $cv->croak ($error)
471		621
472	Similar to send, but causes all call's to C<< ->recv >> to invoke	622	Similar to send, but causes all call's to C<< ->recv >> to invoke
473	C<Carp::croak> with the given error message/object/scalar.	623	C<Carp::croak> with the given error message/object/scalar.
474		624
475	This can be used to signal any errors to the condition variable	625	This can be used to signal any errors to the condition variable
476	user/consumer.	626	user/consumer. Doing it this way instead of calling C<croak> directly
		627	delays the error detetcion, but has the overwhelmign advantage that it
		628	diagnoses the error at the place where the result is expected, and not
		629	deep in some event clalback without connection to the actual code causing
		630	the problem.
477		631
478	=item $cv->begin ([group callback])	632	=item $cv->begin ([group callback])
479		633
480	=item $cv->end	634	=item $cv->end
481
482	These two methods are EXPERIMENTAL and MIGHT CHANGE.
483		635
484	These two methods can be used to combine many transactions/events into	636	These two methods can be used to combine many transactions/events into
485	one. For example, a function that pings many hosts in parallel might want	637	one. For example, a function that pings many hosts in parallel might want
486	to use a condition variable for the whole process.	638	to use a condition variable for the whole process.
487		639
…		…
489	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	641	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
490	>>, the (last) callback passed to C<begin> will be executed. That callback	642	>>, the (last) callback passed to C<begin> will be executed. That callback
491	is I<supposed> to call C<< ->send >>, but that is not required. If no	643	is I<supposed> to call C<< ->send >>, but that is not required. If no
492	callback was set, C<send> will be called without any arguments.	644	callback was set, C<send> will be called without any arguments.
493		645
494	Let's clarify this with the ping example:	646	You can think of C<< $cv->send >> giving you an OR condition (one call
		647	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		648	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		649
		650	Let's start with a simple example: you have two I/O watchers (for example,
		651	STDOUT and STDERR for a program), and you want to wait for both streams to
		652	close before activating a condvar:
		653
		654	my $cv = AnyEvent->condvar;
		655
		656	$cv->begin; # first watcher
		657	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		658	defined sysread $fh1, my $buf, 4096
		659	or $cv->end;
		660	});
		661
		662	$cv->begin; # second watcher
		663	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		664	defined sysread $fh2, my $buf, 4096
		665	or $cv->end;
		666	});
		667
		668	$cv->recv;
		669
		670	This works because for every event source (EOF on file handle), there is
		671	one call to C<begin>, so the condvar waits for all calls to C<end> before
		672	sending.
		673
		674	The ping example mentioned above is slightly more complicated, as the
		675	there are results to be passwd back, and the number of tasks that are
		676	begung can potentially be zero:
495		677
496	my $cv = AnyEvent->condvar;	678	my $cv = AnyEvent->condvar;
497		679
498	my %result;	680	my %result;
499	$cv->begin (sub { $cv->send (\%result) });	681	$cv->begin (sub { $cv->send (\%result) });
…		…
519	loop, which serves two important purposes: first, it sets the callback	701	loop, which serves two important purposes: first, it sets the callback
520	to be called once the counter reaches C<0>, and second, it ensures that	702	to be called once the counter reaches C<0>, and second, it ensures that
521	C<send> is called even when C<no> hosts are being pinged (the loop	703	C<send> is called even when C<no> hosts are being pinged (the loop
522	doesn't execute once).	704	doesn't execute once).
523		705
524	This is the general pattern when you "fan out" into multiple subrequests:	706	This is the general pattern when you "fan out" into multiple (but
525	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	707	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
526	is called at least once, and then, for each subrequest you start, call	708	the callback and ensure C<end> is called at least once, and then, for each
527	C<begin> and for each subrequest you finish, call C<end>.	709	subrequest you start, call C<begin> and for each subrequest you finish,
		710	call C<end>.
528		711
529	=back	712	=back
530		713
531	=head3 METHODS FOR CONSUMERS	714	=head3 METHODS FOR CONSUMERS
532		715
…		…
548	function will call C<croak>.	731	function will call C<croak>.
549		732
550	In list context, all parameters passed to C<send> will be returned,	733	In list context, all parameters passed to C<send> will be returned,
551	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
552		735
		736	Note that doing a blocking wait in a callback is not supported by any
		737	event loop, that is, recursive invocation of a blocking C<< ->recv
		738	>> is not allowed, and the C<recv> call will C<croak> if such a
		739	condition is detected. This condition can be slightly loosened by using
		740	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		741	any thread that doesn't run the event loop itself.
		742
553	Not all event models support a blocking wait - some die in that case	743	Not all event models support a blocking wait - some die in that case
554	(programs might want to do that to stay interactive), so I<if you are	744	(programs might want to do that to stay interactive), so I<if you are
555	using this from a module, never require a blocking wait>, but let the	745	using this from a module, never require a blocking wait>. Instead, let the
556	caller decide whether the call will block or not (for example, by coupling	746	caller decide whether the call will block or not (for example, by coupling
557	condition variables with some kind of request results and supporting	747	condition variables with some kind of request results and supporting
558	callbacks so the caller knows that getting the result will not block,	748	callbacks so the caller knows that getting the result will not block,
559	while still supporting blocking waits if the caller so desires).	749	while still supporting blocking waits if the caller so desires).
560		750
561	Another reason I<never> to C<< ->recv >> in a module is that you cannot
562	sensibly have two C<< ->recv >>'s in parallel, as that would require
563	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
564	can supply.
565
566	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
567	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
568	versions and also integrates coroutines into AnyEvent, making blocking
569	C<< ->recv >> calls perfectly safe as long as they are done from another
570	coroutine (one that doesn't run the event loop).
571
572	You can ensure that C<< -recv >> never blocks by setting a callback and	751	You can ensure that C<< -recv >> never blocks by setting a callback and
573	only calling C<< ->recv >> from within that callback (or at a later	752	only calling C<< ->recv >> from within that callback (or at a later
574	time). This will work even when the event loop does not support blocking	753	time). This will work even when the event loop does not support blocking
575	waits otherwise.	754	waits otherwise.
576		755
577	=item $bool = $cv->ready	756	=item $bool = $cv->ready
578		757
579	Returns true when the condition is "true", i.e. whether C<send> or	758	Returns true when the condition is "true", i.e. whether C<send> or
580	C<croak> have been called.	759	C<croak> have been called.
581		760
582	=item $cb = $cv->cb ([new callback])	761	=item $cb = $cv->cb ($cb->($cv))
583		762
584	This is a mutator function that returns the callback set and optionally	763	This is a mutator function that returns the callback set and optionally
585	replaces it before doing so.	764	replaces it before doing so.
586		765
587	The callback will be called when the condition becomes "true", i.e. when	766	The callback will be called when the condition becomes "true", i.e. when
588	C<send> or C<croak> are called. Calling C<recv> inside the callback	767	C<send> or C<croak> are called, with the only argument being the condition
589	or at any later time is guaranteed not to block.	768	variable itself. Calling C<recv> inside the callback or at any later time
		769	is guaranteed not to block.
590		770
591	=back	771	=back
592		772
		773	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		774
		775	The available backend classes are (every class has its own manpage):
		776
		777	=over 4
		778
		779	=item Backends that are autoprobed when no other event loop can be found.
		780
		781	EV is the preferred backend when no other event loop seems to be in
		782	use. If EV is not installed, then AnyEvent will try Event, and, failing
		783	that, will fall back to its own pure-perl implementation, which is
		784	available everywhere as it comes with AnyEvent itself.
		785
		786	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		787	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		788	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		789
		790	=item Backends that are transparently being picked up when they are used.
		791
		792	These will be used when they are currently loaded when the first watcher
		793	is created, in which case it is assumed that the application is using
		794	them. This means that AnyEvent will automatically pick the right backend
		795	when the main program loads an event module before anything starts to
		796	create watchers. Nothing special needs to be done by the main program.
		797
		798	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		799	AnyEvent::Impl::Tk based on Tk, very broken.
		800	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		801	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		802	AnyEvent::Impl::Irssi used when running within irssi.
		803
		804	=item Backends with special needs.
		805
		806	Qt requires the Qt::Application to be instantiated first, but will
		807	otherwise be picked up automatically. As long as the main program
		808	instantiates the application before any AnyEvent watchers are created,
		809	everything should just work.
		810
		811	AnyEvent::Impl::Qt based on Qt.
		812
		813	Support for IO::Async can only be partial, as it is too broken and
		814	architecturally limited to even support the AnyEvent API. It also
		815	is the only event loop that needs the loop to be set explicitly, so
		816	it can only be used by a main program knowing about AnyEvent. See
		817	L<AnyEvent::Impl::Async> for the gory details.
		818
		819	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		820
		821	=item Event loops that are indirectly supported via other backends.
		822
		823	Some event loops can be supported via other modules:
		824
		825	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		826
		827	B<WxWidgets> has no support for watching file handles. However, you can
		828	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		829	polls 20 times per second, which was considered to be too horrible to even
		830	consider for AnyEvent.
		831
		832	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		833	backend, so it can be supported through POE.
		834
		835	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		836	load L<POE> when detecting them, in the hope that POE will pick them up,
		837	in which case everything will be automatic.
		838
		839	=back
		840
593	=head1 GLOBAL VARIABLES AND FUNCTIONS	841	=head1 GLOBAL VARIABLES AND FUNCTIONS
594		842
		843	These are not normally required to use AnyEvent, but can be useful to
		844	write AnyEvent extension modules.
		845
595	=over 4	846	=over 4
596		847
597	=item $AnyEvent::MODEL	848	=item $AnyEvent::MODEL
598		849
599	Contains C<undef> until the first watcher is being created. Then it	850	Contains C<undef> until the first watcher is being created, before the
		851	backend has been autodetected.
		852
600	contains the event model that is being used, which is the name of the	853	Afterwards it contains the event model that is being used, which is the
601	Perl class implementing the model. This class is usually one of the	854	name of the Perl class implementing the model. This class is usually one
602	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	855	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
603	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	856	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
604		857	will be C<urxvt::anyevent>).
605	The known classes so far are:
606
607	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
608	AnyEvent::Impl::Event based on Event, second best choice.
609	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
610	AnyEvent::Impl::Glib based on Glib, third-best choice.
611	AnyEvent::Impl::Tk based on Tk, very bad choice.
612	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
614	AnyEvent::Impl::POE based on POE, not generic enough for full support.
615
616	There is no support for WxWidgets, as WxWidgets has no support for
617	watching file handles. However, you can use WxWidgets through the
618	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
619	second, which was considered to be too horrible to even consider for
620	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
621	it's adaptor.
622
623	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
624	autodetecting them.
625		858
626	=item AnyEvent::detect	859	=item AnyEvent::detect
627		860
628	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	861	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
629	if necessary. You should only call this function right before you would	862	if necessary. You should only call this function right before you would
630	have created an AnyEvent watcher anyway, that is, as late as possible at	863	have created an AnyEvent watcher anyway, that is, as late as possible at
631	runtime.	864	runtime, and not e.g. while initialising of your module.
		865
		866	If you need to do some initialisation before AnyEvent watchers are
		867	created, use C<post_detect>.
632		868
633	=item $guard = AnyEvent::post_detect { BLOCK }	869	=item $guard = AnyEvent::post_detect { BLOCK }
634		870
635	Arranges for the code block to be executed as soon as the event model is	871	Arranges for the code block to be executed as soon as the event model is
636	autodetected (or immediately if this has already happened).	872	autodetected (or immediately if this has already happened).
637		873
		874	The block will be executed I<after> the actual backend has been detected
		875	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		876	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		877	other initialisations - see the sources of L<AnyEvent::Strict> or
		878	L<AnyEvent::AIO> to see how this is used.
		879
		880	The most common usage is to create some global watchers, without forcing
		881	event module detection too early, for example, L<AnyEvent::AIO> creates
		882	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		883	avoid autodetecting the event module at load time.
		884
638	If called in scalar or list context, then it creates and returns an object	885	If called in scalar or list context, then it creates and returns an object
639	that automatically removes the callback again when it is destroyed. See	886	that automatically removes the callback again when it is destroyed (or
		887	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
640	L<Coro::BDB> for a case where this is useful.	888	a case where this is useful.
		889
		890	Example: Create a watcher for the IO::AIO module and store it in
		891	C<$WATCHER>. Only do so after the event loop is initialised, though.
		892
		893	our WATCHER;
		894
		895	my $guard = AnyEvent::post_detect {
		896	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		897	};
		898
		899	# the ||= is important in case post_detect immediately runs the block,
		900	# as to not clobber the newly-created watcher. assigning both watcher and
		901	# post_detect guard to the same variable has the advantage of users being
		902	# able to just C<undef $WATCHER> if the watcher causes them grief.
		903
		904	$WATCHER ||= $guard;
641		905
642	=item @AnyEvent::post_detect	906	=item @AnyEvent::post_detect
643		907
644	If there are any code references in this array (you can C<push> to it	908	If there are any code references in this array (you can C<push> to it
645	before or after loading AnyEvent), then they will called directly after	909	before or after loading AnyEvent), then they will called directly after
646	the event loop has been chosen.	910	the event loop has been chosen.
647		911
648	You should check C<$AnyEvent::MODEL> before adding to this array, though:	912	You should check C<$AnyEvent::MODEL> before adding to this array, though:
649	if it contains a true value then the event loop has already been detected,	913	if it is defined then the event loop has already been detected, and the
650	and the array will be ignored.	914	array will be ignored.
651		915
652	Best use C<AnyEvent::post_detect { BLOCK }> instead.	916	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		917	it,as it takes care of these details.
		918
		919	This variable is mainly useful for modules that can do something useful
		920	when AnyEvent is used and thus want to know when it is initialised, but do
		921	not need to even load it by default. This array provides the means to hook
		922	into AnyEvent passively, without loading it.
653		923
654	=back	924	=back
655		925
656	=head1 WHAT TO DO IN A MODULE	926	=head1 WHAT TO DO IN A MODULE
657		927
…		…
712		982
713		983
714	=head1 OTHER MODULES	984	=head1 OTHER MODULES
715		985
716	The following is a non-exhaustive list of additional modules that use	986	The following is a non-exhaustive list of additional modules that use
717	AnyEvent and can therefore be mixed easily with other AnyEvent modules	987	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
718	in the same program. Some of the modules come with AnyEvent, some are	988	modules and other event loops in the same program. Some of the modules
719	available via CPAN.	989	come with AnyEvent, most are available via CPAN.
720		990
721	=over 4	991	=over 4
722		992
723	=item L<AnyEvent::Util>	993	=item L<AnyEvent::Util>
724		994
725	Contains various utility functions that replace often-used but blocking	995	Contains various utility functions that replace often-used but blocking
726	functions such as C<inet_aton> by event-/callback-based versions.	996	functions such as C<inet_aton> by event-/callback-based versions.
727
728	=item L<AnyEvent::Handle>
729
730	Provide read and write buffers and manages watchers for reads and writes.
731		997
732	=item L<AnyEvent::Socket>	998	=item L<AnyEvent::Socket>
733		999
734	Provides various utility functions for (internet protocol) sockets,	1000	Provides various utility functions for (internet protocol) sockets,
735	addresses and name resolution. Also functions to create non-blocking tcp	1001	addresses and name resolution. Also functions to create non-blocking tcp
736	connections or tcp servers, with IPv6 and SRV record support and more.	1002	connections or tcp servers, with IPv6 and SRV record support and more.
737		1003
		1004	=item L<AnyEvent::Handle>
		1005
		1006	Provide read and write buffers, manages watchers for reads and writes,
		1007	supports raw and formatted I/O, I/O queued and fully transparent and
		1008	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1009
738	=item L<AnyEvent::DNS>	1010	=item L<AnyEvent::DNS>
739		1011
740	Provides rich asynchronous DNS resolver capabilities.	1012	Provides rich asynchronous DNS resolver capabilities.
741		1013
		1014	=item L<AnyEvent::HTTP>
		1015
		1016	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1017	HTTP requests.
		1018
742	=item L<AnyEvent::HTTPD>	1019	=item L<AnyEvent::HTTPD>
743		1020
744	Provides a simple web application server framework.	1021	Provides a simple web application server framework.
745		1022
746	=item L<AnyEvent::FastPing>	1023	=item L<AnyEvent::FastPing>
747		1024
748	The fastest ping in the west.	1025	The fastest ping in the west.
749		1026
		1027	=item L<AnyEvent::DBI>
		1028
		1029	Executes L<DBI> requests asynchronously in a proxy process.
		1030
		1031	=item L<AnyEvent::AIO>
		1032
		1033	Truly asynchronous I/O, should be in the toolbox of every event
		1034	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1035	together.
		1036
		1037	=item L<AnyEvent::BDB>
		1038
		1039	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1040	L<BDB> and AnyEvent together.
		1041
		1042	=item L<AnyEvent::GPSD>
		1043
		1044	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1045
750	=item L<Net::IRC3>	1046	=item L<AnyEvent::IRC>
751		1047
752	AnyEvent based IRC client module family.	1048	AnyEvent based IRC client module family (replacing the older Net::IRC3).
753		1049
754	=item L<Net::XMPP2>	1050	=item L<AnyEvent::XMPP>
755		1051
756	AnyEvent based XMPP (Jabber protocol) module family.	1052	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1053	Net::XMPP2>.
		1054
		1055	=item L<AnyEvent::IGS>
		1056
		1057	A non-blocking interface to the Internet Go Server protocol (used by
		1058	L<App::IGS>).
757		1059
758	=item L<Net::FCP>	1060	=item L<Net::FCP>
759		1061
760	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1062	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
761	of AnyEvent.	1063	of AnyEvent.
…		…
766		1068
767	=item L<Coro>	1069	=item L<Coro>
768		1070
769	Has special support for AnyEvent via L<Coro::AnyEvent>.	1071	Has special support for AnyEvent via L<Coro::AnyEvent>.
770		1072
771	=item L<AnyEvent::AIO>, L<IO::AIO>
772
773	Truly asynchronous I/O, should be in the toolbox of every event
774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
775	together.
776
777	=item L<AnyEvent::BDB>, L<BDB>
778
779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
780	IO::AIO and AnyEvent together.
781
782	=item L<IO::Lambda>
783
784	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
785
786	=back	1073	=back
787		1074
788	=cut	1075	=cut
789		1076
790	package AnyEvent;	1077	package AnyEvent;
791		1078
		1079	# basically a tuned-down version of common::sense
		1080	sub common_sense {
792	no warnings;	1081	# no warnings
793	use strict;	1082	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1083	# use strict vars subs
		1084	$^H |= 0x00000600;
		1085	}
794		1086
		1087	BEGIN { AnyEvent::common_sense }
		1088
795	use Carp;	1089	use Carp ();
796		1090
797	our $VERSION = '4.05';	1091	our $VERSION = 4.881;
798	our $MODEL;	1092	our $MODEL;
799		1093
800	our $AUTOLOAD;	1094	our $AUTOLOAD;
801	our @ISA;	1095	our @ISA;
802		1096
803	our @REGISTRY;	1097	our @REGISTRY;
804		1098
805	our $WIN32;	1099	our $WIN32;
806		1100
		1101	our $VERBOSE;
		1102
807	BEGIN {	1103	BEGIN {
808	my $win32 = ! ! ($^O =~ /mswin32/i);	1104	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
809	eval "sub WIN32(){ $win32 }";	1105	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
810	}
811		1106
		1107	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1108	if ${^TAINT};
		1109
812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1110	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1111
		1112	}
		1113
		1114	our $MAX_SIGNAL_LATENCY = 10;
813		1115
814	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1116	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
815		1117
816	{	1118	{
817	my $idx;	1119	my $idx;
…		…
819	for reverse split /\s*,\s*/,	1121	for reverse split /\s*,\s*/,
820	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1122	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
821	}	1123	}
822		1124
823	my @models = (	1125	my @models = (
824	[EV:: => AnyEvent::Impl::EV::],	1126	[EV:: => AnyEvent::Impl::EV:: , 1],
825	[Event:: => AnyEvent::Impl::Event::],	1127	[Event:: => AnyEvent::Impl::Event::, 1],
826	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1128	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
827	# everything below here will not be autoprobed	1129	# everything below here will not (normally) be autoprobed
828	# as the pureperl backend should work everywhere	1130	# as the pureperl backend should work everywhere
829	# and is usually faster	1131	# and is usually faster
		1132	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1133	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1134	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
830	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1135	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
831	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1136	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1137	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
835	[Wx:: => AnyEvent::Impl::POE::],	1138	[Wx:: => AnyEvent::Impl::POE::],
836	[Prima:: => AnyEvent::Impl::POE::],	1139	[Prima:: => AnyEvent::Impl::POE::],
		1140	# IO::Async is just too broken - we would need workarounds for its
		1141	# byzantine signal and broken child handling, among others.
		1142	# IO::Async is rather hard to detect, as it doesn't have any
		1143	# obvious default class.
		1144	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1145	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1146	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
837	);	1147	);
838		1148
839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1149	our %method = map +($_ => 1),
		1150	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
840		1151
841	our @post_detect;	1152	our @post_detect;
842		1153
843	sub post_detect(&) {	1154	sub post_detect(&) {
844	my ($cb) = @_;	1155	my ($cb) = @_;
845		1156
846	if ($MODEL) {	1157	if ($MODEL) {
847	$cb->();	1158	$cb->();
848		1159
849	1	1160	undef
850	} else {	1161	} else {
851	push @post_detect, $cb;	1162	push @post_detect, $cb;
852		1163
853	defined wantarray	1164	defined wantarray
854	? bless \$cb, "AnyEvent::Util::PostDetect"	1165	? bless \$cb, "AnyEvent::Util::postdetect"
855	: ()	1166	: ()
856	}	1167	}
857	}	1168	}
858		1169
859	sub AnyEvent::Util::PostDetect::DESTROY {	1170	sub AnyEvent::Util::postdetect::DESTROY {
860	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1171	@post_detect = grep $_ != ${$_[0]}, @post_detect;
861	}	1172	}
862		1173
863	sub detect() {	1174	sub detect() {
864	unless ($MODEL) {	1175	unless ($MODEL) {
865	no strict 'refs';
866	local $SIG{__DIE__};	1176	local $SIG{__DIE__};
867		1177
868	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1178	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
869	my $model = "AnyEvent::Impl::$1";	1179	my $model = "AnyEvent::Impl::$1";
870	if (eval "require $model") {	1180	if (eval "require $model") {
871	$MODEL = $model;	1181	$MODEL = $model;
872	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1182	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
873	} else {	1183	} else {
874	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1184	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
875	}	1185	}
876	}	1186	}
877		1187
878	# check for already loaded models	1188	# check for already loaded models
879	unless ($MODEL) {	1189	unless ($MODEL) {
880	for (@REGISTRY, @models) {	1190	for (@REGISTRY, @models) {
881	my ($package, $model) = @$_;	1191	my ($package, $model) = @$_;
882	if (${"$package\::VERSION"} > 0) {	1192	if (${"$package\::VERSION"} > 0) {
883	if (eval "require $model") {	1193	if (eval "require $model") {
884	$MODEL = $model;	1194	$MODEL = $model;
885	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1195	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
886	last;	1196	last;
887	}	1197	}
888	}	1198	}
889	}	1199	}
890		1200
891	unless ($MODEL) {	1201	unless ($MODEL) {
892	# try to load a model	1202	# try to autoload a model
893
894	for (@REGISTRY, @models) {	1203	for (@REGISTRY, @models) {
895	my ($package, $model) = @$_;	1204	my ($package, $model, $autoload) = @$_;
		1205	if (
		1206	$autoload
896	if (eval "require $package"	1207	and eval "require $package"
897	and ${"$package\::VERSION"} > 0	1208	and ${"$package\::VERSION"} > 0
898	and eval "require $model") {	1209	and eval "require $model"
		1210	) {
899	$MODEL = $model;	1211	$MODEL = $model;
900	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1212	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
901	last;	1213	last;
902	}	1214	}
903	}	1215	}
904		1216
905	$MODEL	1217	$MODEL
906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1218	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
907	}	1219	}
908	}	1220	}
909		1221
		1222	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1223
910	unshift @ISA, $MODEL;	1224	unshift @ISA, $MODEL;
911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1225
		1226	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
912		1227
913	(shift @post_detect)->() while @post_detect;	1228	(shift @post_detect)->() while @post_detect;
914	}	1229	}
915		1230
916	$MODEL	1231	$MODEL
…		…
918		1233
919	sub AUTOLOAD {	1234	sub AUTOLOAD {
920	(my $func = $AUTOLOAD) =~ s/.*://;	1235	(my $func = $AUTOLOAD) =~ s/.*://;
921		1236
922	$method{$func}	1237	$method{$func}
923	or croak "$func: not a valid method for AnyEvent objects";	1238	or Carp::croak "$func: not a valid method for AnyEvent objects";
924		1239
925	detect unless $MODEL;	1240	detect unless $MODEL;
926		1241
927	my $class = shift;	1242	my $class = shift;
928	$class->$func (@_);	1243	$class->$func (@_);
929	}	1244	}
930		1245
		1246	# utility function to dup a filehandle. this is used by many backends
		1247	# to support binding more than one watcher per filehandle (they usually
		1248	# allow only one watcher per fd, so we dup it to get a different one).
		1249	sub _dupfh($$;$$) {
		1250	my ($poll, $fh, $r, $w) = @_;
		1251
		1252	# cygwin requires the fh mode to be matching, unix doesn't
		1253	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1254
		1255	open my $fh2, $mode, $fh
		1256	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1257
		1258	# we assume CLOEXEC is already set by perl in all important cases
		1259
		1260	($fh2, $rw)
		1261	}
		1262
931	package AnyEvent::Base;	1263	package AnyEvent::Base;
932		1264
933	# default implementation for now and time	1265	# default implementations for many methods
934		1266
935	use Time::HiRes ();	1267	sub _time {
		1268	# probe for availability of Time::HiRes
		1269	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1270	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1271	*_time = \&Time::HiRes::time;
		1272	# if (eval "use POSIX (); (POSIX::times())...
		1273	} else {
		1274	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1275	*_time = sub { time }; # epic fail
		1276	}
936		1277
937	sub time { Time::HiRes::time }	1278	&_time
938	sub now { Time::HiRes::time }	1279	}
		1280
		1281	sub time { _time }
		1282	sub now { _time }
		1283	sub now_update { }
939		1284
940	# default implementation for ->condvar	1285	# default implementation for ->condvar
941		1286
942	sub condvar {	1287	sub condvar {
943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1288	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
944	}	1289	}
945		1290
946	# default implementation for ->signal	1291	# default implementation for ->signal
947		1292
948	our %SIG_CB;	1293	our $HAVE_ASYNC_INTERRUPT;
949		1294
		1295	sub _have_async_interrupt() {
		1296	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1297	&& eval "use Async::Interrupt 1.0 (); 1")
		1298	unless defined $HAVE_ASYNC_INTERRUPT;
		1299
		1300	$HAVE_ASYNC_INTERRUPT
		1301	}
		1302
		1303	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1304	our (%SIG_ASY, %SIG_ASY_W);
		1305	our ($SIG_COUNT, $SIG_TW);
		1306
		1307	sub _signal_exec {
		1308	$HAVE_ASYNC_INTERRUPT
		1309	? $SIGPIPE_R->drain
		1310	: sysread $SIGPIPE_R, my $dummy, 9;
		1311
		1312	while (%SIG_EV) {
		1313	for (keys %SIG_EV) {
		1314	delete $SIG_EV{$_};
		1315	$_->() for values %{ $SIG_CB{$_} || {} };
		1316	}
		1317	}
		1318	}
		1319
		1320	# install a dummy wakeup watcher to reduce signal catching latency
		1321	sub _sig_add() {
		1322	unless ($SIG_COUNT++) {
		1323	# try to align timer on a full-second boundary, if possible
		1324	my $NOW = AnyEvent->now;
		1325
		1326	$SIG_TW = AnyEvent->timer (
		1327	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1328	interval => $MAX_SIGNAL_LATENCY,
		1329	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1330	);
		1331	}
		1332	}
		1333
		1334	sub _sig_del {
		1335	undef $SIG_TW
		1336	unless --$SIG_COUNT;
		1337	}
		1338
		1339	our $_sig_name_init; $_sig_name_init = sub {
		1340	undef $_sig_name_init;
		1341
		1342	if (_have_async_interrupt) {
		1343	*sig2num = \&Async::Interrupt::sig2num;
		1344	*sig2name = \&Async::Interrupt::sig2name;
		1345	} else {
		1346	require Config;
		1347
		1348	my %signame2num;
		1349	@signame2num{ split ' ', $Config::Config{sig_name} }
		1350	= split ' ', $Config::Config{sig_num};
		1351
		1352	my @signum2name;
		1353	@signum2name[values %signame2num] = keys %signame2num;
		1354
		1355	*sig2num = sub($) {
		1356	$_[0] > 0 ? shift : $signame2num{+shift}
		1357	};
		1358	*sig2name = sub ($) {
		1359	$_[0] > 0 ? $signum2name[+shift] : shift
		1360	};
		1361	}
		1362	};
		1363
		1364	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1365	sub sig2name($) { &$_sig_name_init; &sig2name }
		1366
950	sub signal {	1367	sub _signal {
951	my (undef, %arg) = @_;	1368	my (undef, %arg) = @_;
952		1369
953	my $signal = uc $arg{signal}	1370	my $signal = uc $arg{signal}
954	or Carp::croak "required option 'signal' is missing";	1371	or Carp::croak "required option 'signal' is missing";
955		1372
		1373	if ($HAVE_ASYNC_INTERRUPT) {
		1374	# async::interrupt
		1375
		1376	$signal = sig2num $signal;
956	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1377	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1378
		1379	$SIG_ASY{$signal} ||= new Async::Interrupt
		1380	cb => sub { undef $SIG_EV{$signal} },
		1381	signal => $signal,
		1382	pipe => [$SIGPIPE_R->filenos],
		1383	pipe_autodrain => 0,
		1384	;
		1385
		1386	} else {
		1387	# pure perl
		1388
		1389	# AE::Util has been loaded in signal
		1390	$signal = sig2name $signal;
		1391	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1392
957	$SIG{$signal} ||= sub {	1393	$SIG{$signal} ||= sub {
958	$_->() for values %{ $SIG_CB{$signal} || {} };	1394	local $!;
		1395	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1396	undef $SIG_EV{$signal};
		1397	};
		1398
		1399	# can't do signal processing without introducing races in pure perl,
		1400	# so limit the signal latency.
		1401	_sig_add;
959	};	1402	}
960		1403
961	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1404	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
962	}	1405	}
963		1406
		1407	sub signal {
		1408	# probe for availability of Async::Interrupt
		1409	if (_have_async_interrupt) {
		1410	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1411
		1412	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1413	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1414
		1415	} else {
		1416	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1417
		1418	require Fcntl;
		1419
		1420	if (AnyEvent::WIN32) {
		1421	require AnyEvent::Util;
		1422
		1423	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1424	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1425	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1426	} else {
		1427	pipe $SIGPIPE_R, $SIGPIPE_W;
		1428	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1429	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1430
		1431	# not strictly required, as $^F is normally 2, but let's make sure...
		1432	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1433	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1434	}
		1435
		1436	$SIGPIPE_R
		1437	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1438
		1439	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1440	}
		1441
		1442	*signal = \&_signal;
		1443	&signal
		1444	}
		1445
964	sub AnyEvent::Base::Signal::DESTROY {	1446	sub AnyEvent::Base::signal::DESTROY {
965	my ($signal, $cb) = @{$_[0]};	1447	my ($signal, $cb) = @{$_[0]};
966		1448
		1449	_sig_del;
		1450
967	delete $SIG_CB{$signal}{$cb};	1451	delete $SIG_CB{$signal}{$cb};
968		1452
969	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1453	$HAVE_ASYNC_INTERRUPT
		1454	? delete $SIG_ASY{$signal}
		1455	: # delete doesn't work with older perls - they then
		1456	# print weird messages, or just unconditionally exit
		1457	# instead of getting the default action.
		1458	undef $SIG{$signal}
		1459	unless keys %{ $SIG_CB{$signal} };
970	}	1460	}
971		1461
972	# default implementation for ->child	1462	# default implementation for ->child
973		1463
974	our %PID_CB;	1464	our %PID_CB;
975	our $CHLD_W;	1465	our $CHLD_W;
976	our $CHLD_DELAY_W;	1466	our $CHLD_DELAY_W;
977	our $PID_IDLE;
978	our $WNOHANG;	1467	our $WNOHANG;
979		1468
980	sub _child_wait {	1469	sub _emit_childstatus($$) {
981	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1470	my (undef, $rpid, $rstatus) = @_;
		1471
		1472	$_->($rpid, $rstatus)
982	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1473	for values %{ $PID_CB{$rpid} || {} },
983	(values %{ $PID_CB{0} || {} });	1474	values %{ $PID_CB{0} || {} };
984	}
985
986	undef $PID_IDLE;
987	}	1475	}
988		1476
989	sub _sigchld {	1477	sub _sigchld {
990	# make sure we deliver these changes "synchronous" with the event loop.	1478	my $pid;
991	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1479
992	undef $CHLD_DELAY_W;	1480	AnyEvent->_emit_childstatus ($pid, $?)
993	&_child_wait;	1481	while ($pid = waitpid -1, $WNOHANG) > 0;
994	});
995	}	1482	}
996		1483
997	sub child {	1484	sub child {
998	my (undef, %arg) = @_;	1485	my (undef, %arg) = @_;
999		1486
1000	defined (my $pid = $arg{pid} + 0)	1487	defined (my $pid = $arg{pid} + 0)
1001	or Carp::croak "required option 'pid' is missing";	1488	or Carp::croak "required option 'pid' is missing";
1002		1489
1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1490	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1004		1491
1005	unless ($WNOHANG) {	1492	# WNOHANG is almost cetrainly 1 everywhere
		1493	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1494	? 1
1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1495	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1007	}
1008		1496
1009	unless ($CHLD_W) {	1497	unless ($CHLD_W) {
1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1498	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1011	# child could be a zombie already, so make at least one round	1499	# child could be a zombie already, so make at least one round
1012	&_sigchld;	1500	&_sigchld;
1013	}	1501	}
1014		1502
1015	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1503	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1016	}	1504	}
1017		1505
1018	sub AnyEvent::Base::Child::DESTROY {	1506	sub AnyEvent::Base::child::DESTROY {
1019	my ($pid, $cb) = @{$_[0]};	1507	my ($pid, $cb) = @{$_[0]};
1020		1508
1021	delete $PID_CB{$pid}{$cb};	1509	delete $PID_CB{$pid}{$cb};
1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1510	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1023		1511
1024	undef $CHLD_W unless keys %PID_CB;	1512	undef $CHLD_W unless keys %PID_CB;
1025	}	1513	}
1026		1514
		1515	# idle emulation is done by simply using a timer, regardless
		1516	# of whether the process is idle or not, and not letting
		1517	# the callback use more than 50% of the time.
		1518	sub idle {
		1519	my (undef, %arg) = @_;
		1520
		1521	my ($cb, $w, $rcb) = $arg{cb};
		1522
		1523	$rcb = sub {
		1524	if ($cb) {
		1525	$w = _time;
		1526	&$cb;
		1527	$w = _time - $w;
		1528
		1529	# never use more then 50% of the time for the idle watcher,
		1530	# within some limits
		1531	$w = 0.0001 if $w < 0.0001;
		1532	$w = 5 if $w > 5;
		1533
		1534	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1535	} else {
		1536	# clean up...
		1537	undef $w;
		1538	undef $rcb;
		1539	}
		1540	};
		1541
		1542	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1543
		1544	bless \\$cb, "AnyEvent::Base::idle"
		1545	}
		1546
		1547	sub AnyEvent::Base::idle::DESTROY {
		1548	undef $${$_[0]};
		1549	}
		1550
1027	package AnyEvent::CondVar;	1551	package AnyEvent::CondVar;
1028		1552
1029	our @ISA = AnyEvent::CondVar::Base::;	1553	our @ISA = AnyEvent::CondVar::Base::;
1030		1554
1031	package AnyEvent::CondVar::Base;	1555	package AnyEvent::CondVar::Base;
1032		1556
1033	use overload	1557	#use overload
1034	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1558	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1035	fallback => 1;	1559	# fallback => 1;
		1560
		1561	# save 300+ kilobytes by dirtily hardcoding overloading
		1562	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1563	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1564	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1565	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1566
		1567	our $WAITING;
1036		1568
1037	sub _send {	1569	sub _send {
1038	# nop	1570	# nop
1039	}	1571	}
1040		1572
…		…
1053	sub ready {	1585	sub ready {
1054	$_[0]{_ae_sent}	1586	$_[0]{_ae_sent}
1055	}	1587	}
1056		1588
1057	sub _wait {	1589	sub _wait {
		1590	$WAITING
		1591	and !$_[0]{_ae_sent}
		1592	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1593
		1594	local $WAITING = 1;
1058	AnyEvent->one_event while !$_[0]{_ae_sent};	1595	AnyEvent->one_event while !$_[0]{_ae_sent};
1059	}	1596	}
1060		1597
1061	sub recv {	1598	sub recv {
1062	$_[0]->_wait;	1599	$_[0]->_wait;
…		…
1081	}	1618	}
1082		1619
1083	# undocumented/compatibility with pre-3.4	1620	# undocumented/compatibility with pre-3.4
1084	*broadcast = \&send;	1621	*broadcast = \&send;
1085	*wait = \&_wait;	1622	*wait = \&_wait;
		1623
		1624	=head1 ERROR AND EXCEPTION HANDLING
		1625
		1626	In general, AnyEvent does not do any error handling - it relies on the
		1627	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1628	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1629	checking of all AnyEvent methods, however, which is highly useful during
		1630	development.
		1631
		1632	As for exception handling (i.e. runtime errors and exceptions thrown while
		1633	executing a callback), this is not only highly event-loop specific, but
		1634	also not in any way wrapped by this module, as this is the job of the main
		1635	program.
		1636
		1637	The pure perl event loop simply re-throws the exception (usually
		1638	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1639	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1640	so on.
		1641
		1642	=head1 ENVIRONMENT VARIABLES
		1643
		1644	The following environment variables are used by this module or its
		1645	submodules.
		1646
		1647	Note that AnyEvent will remove I<all> environment variables starting with
		1648	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1649	enabled.
		1650
		1651	=over 4
		1652
		1653	=item C<PERL_ANYEVENT_VERBOSE>
		1654
		1655	By default, AnyEvent will be completely silent except in fatal
		1656	conditions. You can set this environment variable to make AnyEvent more
		1657	talkative.
		1658
		1659	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1660	conditions, such as not being able to load the event model specified by
		1661	C<PERL_ANYEVENT_MODEL>.
		1662
		1663	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1664	model it chooses.
		1665
		1666	When set to C<8> or higher, then AnyEvent will report extra information on
		1667	which optional modules it loads and how it implements certain features.
		1668
		1669	=item C<PERL_ANYEVENT_STRICT>
		1670
		1671	AnyEvent does not do much argument checking by default, as thorough
		1672	argument checking is very costly. Setting this variable to a true value
		1673	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1674	check the arguments passed to most method calls. If it finds any problems,
		1675	it will croak.
		1676
		1677	In other words, enables "strict" mode.
		1678
		1679	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1680	>>, it is definitely recommended to keep it off in production. Keeping
		1681	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1682	can be very useful, however.
		1683
		1684	=item C<PERL_ANYEVENT_MODEL>
		1685
		1686	This can be used to specify the event model to be used by AnyEvent, before
		1687	auto detection and -probing kicks in. It must be a string consisting
		1688	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1689	and the resulting module name is loaded and if the load was successful,
		1690	used as event model. If it fails to load AnyEvent will proceed with
		1691	auto detection and -probing.
		1692
		1693	This functionality might change in future versions.
		1694
		1695	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1696	could start your program like this:
		1697
		1698	PERL_ANYEVENT_MODEL=Perl perl ...
		1699
		1700	=item C<PERL_ANYEVENT_PROTOCOLS>
		1701
		1702	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1703	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1704	of auto probing).
		1705
		1706	Must be set to a comma-separated list of protocols or address families,
		1707	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1708	used, and preference will be given to protocols mentioned earlier in the
		1709	list.
		1710
		1711	This variable can effectively be used for denial-of-service attacks
		1712	against local programs (e.g. when setuid), although the impact is likely
		1713	small, as the program has to handle conenction and other failures anyways.
		1714
		1715	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1716	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1717	- only support IPv4, never try to resolve or contact IPv6
		1718	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1719	IPv6, but prefer IPv6 over IPv4.
		1720
		1721	=item C<PERL_ANYEVENT_EDNS0>
		1722
		1723	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1724	for DNS. This extension is generally useful to reduce DNS traffic, but
		1725	some (broken) firewalls drop such DNS packets, which is why it is off by
		1726	default.
		1727
		1728	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1729	EDNS0 in its DNS requests.
		1730
		1731	=item C<PERL_ANYEVENT_MAX_FORKS>
		1732
		1733	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1734	will create in parallel.
		1735
		1736	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1737
		1738	The default value for the C<max_outstanding> parameter for the default DNS
		1739	resolver - this is the maximum number of parallel DNS requests that are
		1740	sent to the DNS server.
		1741
		1742	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1743
		1744	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1745	configuration) in the default resolver. When set to the empty string, no
		1746	default config will be used.
		1747
		1748	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1749
		1750	When neither C<ca_file> nor C<ca_path> was specified during
		1751	L<AnyEvent::TLS> context creation, and either of these environment
		1752	variables exist, they will be used to specify CA certificate locations
		1753	instead of a system-dependent default.
		1754
		1755	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1756
		1757	When these are set to C<1>, then the respective modules are not
		1758	loaded. Mostly good for testing AnyEvent itself.
		1759
		1760	=back
1086		1761
1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1762	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1088		1763
1089	This is an advanced topic that you do not normally need to use AnyEvent in	1764	This is an advanced topic that you do not normally need to use AnyEvent in
1090	a module. This section is only of use to event loop authors who want to	1765	a module. This section is only of use to event loop authors who want to
…		…
1124		1799
1125	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1800	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1126	condition variables: code blocking while waiting for a condition will	1801	condition variables: code blocking while waiting for a condition will
1127	C<die>. This still works with most modules/usages, and blocking calls must	1802	C<die>. This still works with most modules/usages, and blocking calls must
1128	not be done in an interactive application, so it makes sense.	1803	not be done in an interactive application, so it makes sense.
1129
1130	=head1 ENVIRONMENT VARIABLES
1131
1132	The following environment variables are used by this module:
1133
1134	=over 4
1135
1136	=item C<PERL_ANYEVENT_VERBOSE>
1137
1138	By default, AnyEvent will be completely silent except in fatal
1139	conditions. You can set this environment variable to make AnyEvent more
1140	talkative.
1141
1142	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1143	conditions, such as not being able to load the event model specified by
1144	C<PERL_ANYEVENT_MODEL>.
1145
1146	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1147	model it chooses.
1148
1149	=item C<PERL_ANYEVENT_MODEL>
1150
1151	This can be used to specify the event model to be used by AnyEvent, before
1152	auto detection and -probing kicks in. It must be a string consisting
1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1154	and the resulting module name is loaded and if the load was successful,
1155	used as event model. If it fails to load AnyEvent will proceed with
1156	auto detection and -probing.
1157
1158	This functionality might change in future versions.
1159
1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1161	could start your program like this:
1162
1163	PERL_ANYEVENT_MODEL=Perl perl ...
1164
1165	=item C<PERL_ANYEVENT_PROTOCOLS>
1166
1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1169	of auto probing).
1170
1171	Must be set to a comma-separated list of protocols or address families,
1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1173	used, and preference will be given to protocols mentioned earlier in the
1174	list.
1175
1176	This variable can effectively be used for denial-of-service attacks
1177	against local programs (e.g. when setuid), although the impact is likely
1178	small, as the program has to handle connection errors already-
1179
1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1182	- only support IPv4, never try to resolve or contact IPv6
1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1184	IPv6, but prefer IPv6 over IPv4.
1185
1186	=item C<PERL_ANYEVENT_EDNS0>
1187
1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic, but
1190	some (broken) firewalls drop such DNS packets, which is why it is off by
1191	default.
1192
1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1194	EDNS0 in its DNS requests.
1195
1196	=item C<PERL_ANYEVENT_MAX_FORKS>
1197
1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1199	will create in parallel.
1200
1201	=back
1202		1804
1203	=head1 EXAMPLE PROGRAM	1805	=head1 EXAMPLE PROGRAM
1204		1806
1205	The following program uses an I/O watcher to read data from STDIN, a timer	1807	The following program uses an I/O watcher to read data from STDIN, a timer
1206	to display a message once per second, and a condition variable to quit the	1808	to display a message once per second, and a condition variable to quit the
…		…
1400	watcher.	2002	watcher.
1401		2003
1402	=head3 Results	2004	=head3 Results
1403		2005
1404	name watchers bytes create invoke destroy comment	2006	name watchers bytes create invoke destroy comment
1405	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2007	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1406	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2008	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1407	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2009	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1408	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2010	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1409	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2011	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1410	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2012	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2013	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2014	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1411	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2015	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1412	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2016	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1413	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2017	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1414	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2018	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1415		2019
1416	=head3 Discussion	2020	=head3 Discussion
1417		2021
1418	The benchmark does I<not> measure scalability of the event loop very	2022	The benchmark does I<not> measure scalability of the event loop very
1419	well. For example, a select-based event loop (such as the pure perl one)	2023	well. For example, a select-based event loop (such as the pure perl one)
…		…
1444	performance becomes really bad with lots of file descriptors (and few of	2048	performance becomes really bad with lots of file descriptors (and few of
1445	them active), of course, but this was not subject of this benchmark.	2049	them active), of course, but this was not subject of this benchmark.
1446		2050
1447	The C<Event> module has a relatively high setup and callback invocation	2051	The C<Event> module has a relatively high setup and callback invocation
1448	cost, but overall scores in on the third place.	2052	cost, but overall scores in on the third place.
		2053
		2054	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2055	when using its pure perl backend.
1449		2056
1450	C<Glib>'s memory usage is quite a bit higher, but it features a	2057	C<Glib>'s memory usage is quite a bit higher, but it features a
1451	faster callback invocation and overall ends up in the same class as	2058	faster callback invocation and overall ends up in the same class as
1452	C<Event>. However, Glib scales extremely badly, doubling the number of	2059	C<Event>. However, Glib scales extremely badly, doubling the number of
1453	watchers increases the processing time by more than a factor of four,	2060	watchers increases the processing time by more than a factor of four,
…		…
1531	it to another server. This includes deleting the old timeout and creating	2138	it to another server. This includes deleting the old timeout and creating
1532	a new one that moves the timeout into the future.	2139	a new one that moves the timeout into the future.
1533		2140
1534	=head3 Results	2141	=head3 Results
1535		2142
1536	name sockets create request	2143	name sockets create request
1537	EV 20000 69.01 11.16	2144	EV 20000 69.01 11.16
1538	Perl 20000 73.32 35.87	2145	Perl 20000 73.32 35.87
		2146	IOAsync 20000 157.00 98.14 epoll
		2147	IOAsync 20000 159.31 616.06 poll
1539	Event 20000 212.62 257.32	2148	Event 20000 212.62 257.32
1540	Glib 20000 651.16 1896.30	2149	Glib 20000 651.16 1896.30
1541	POE 20000 349.67 12317.24 uses POE::Loop::Event	2150	POE 20000 349.67 12317.24 uses POE::Loop::Event
1542		2151
1543	=head3 Discussion	2152	=head3 Discussion
1544		2153
1545	This benchmark I<does> measure scalability and overall performance of the	2154	This benchmark I<does> measure scalability and overall performance of the
1546	particular event loop.	2155	particular event loop.
…		…
1548	EV is again fastest. Since it is using epoll on my system, the setup time	2157	EV is again fastest. Since it is using epoll on my system, the setup time
1549	is relatively high, though.	2158	is relatively high, though.
1550		2159
1551	Perl surprisingly comes second. It is much faster than the C-based event	2160	Perl surprisingly comes second. It is much faster than the C-based event
1552	loops Event and Glib.	2161	loops Event and Glib.
		2162
		2163	IO::Async performs very well when using its epoll backend, and still quite
		2164	good compared to Glib when using its pure perl backend.
1553		2165
1554	Event suffers from high setup time as well (look at its code and you will	2166	Event suffers from high setup time as well (look at its code and you will
1555	understand why). Callback invocation also has a high overhead compared to	2167	understand why). Callback invocation also has a high overhead compared to
1556	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2168	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1557	uses select or poll in basically all documented configurations.	2169	uses select or poll in basically all documented configurations.
…		…
1620	=item * C-based event loops perform very well with small number of	2232	=item * C-based event loops perform very well with small number of
1621	watchers, as the management overhead dominates.	2233	watchers, as the management overhead dominates.
1622		2234
1623	=back	2235	=back
1624		2236
		2237	=head2 THE IO::Lambda BENCHMARK
		2238
		2239	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2240	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2241	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2242	shouldn't come as a surprise to anybody). As such, the benchmark is
		2243	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2244	very optimal. But how would AnyEvent compare when used without the extra
		2245	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2246
		2247	The benchmark itself creates an echo-server, and then, for 500 times,
		2248	connects to the echo server, sends a line, waits for the reply, and then
		2249	creates the next connection. This is a rather bad benchmark, as it doesn't
		2250	test the efficiency of the framework or much non-blocking I/O, but it is a
		2251	benchmark nevertheless.
		2252
		2253	name runtime
		2254	Lambda/select 0.330 sec
		2255	+ optimized 0.122 sec
		2256	Lambda/AnyEvent 0.327 sec
		2257	+ optimized 0.138 sec
		2258	Raw sockets/select 0.077 sec
		2259	POE/select, components 0.662 sec
		2260	POE/select, raw sockets 0.226 sec
		2261	POE/select, optimized 0.404 sec
		2262
		2263	AnyEvent/select/nb 0.085 sec
		2264	AnyEvent/EV/nb 0.068 sec
		2265	+state machine 0.134 sec
		2266
		2267	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2268	benchmarks actually make blocking connects and use 100% blocking I/O,
		2269	defeating the purpose of an event-based solution. All of the newly
		2270	written AnyEvent benchmarks use 100% non-blocking connects (using
		2271	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2272	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2273	generally require a lot more bookkeeping and event handling than blocking
		2274	connects (which involve a single syscall only).
		2275
		2276	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2277	offers similar expressive power as POE and IO::Lambda, using conventional
		2278	Perl syntax. This means that both the echo server and the client are 100%
		2279	non-blocking, further placing it at a disadvantage.
		2280
		2281	As you can see, the AnyEvent + EV combination even beats the
		2282	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2283	backend easily beats IO::Lambda and POE.
		2284
		2285	And even the 100% non-blocking version written using the high-level (and
		2286	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2287	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2288	in a non-blocking way.
		2289
		2290	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2291	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2292	part of the IO::lambda distribution and were used without any changes.
		2293
		2294
		2295	=head1 SIGNALS
		2296
		2297	AnyEvent currently installs handlers for these signals:
		2298
		2299	=over 4
		2300
		2301	=item SIGCHLD
		2302
		2303	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2304	emulation for event loops that do not support them natively. Also, some
		2305	event loops install a similar handler.
		2306
		2307	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2308	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2309
		2310	=item SIGPIPE
		2311
		2312	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2313	when AnyEvent gets loaded.
		2314
		2315	The rationale for this is that AnyEvent users usually do not really depend
		2316	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2317	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2318	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2319	some random socket.
		2320
		2321	The rationale for installing a no-op handler as opposed to ignoring it is
		2322	that this way, the handler will be restored to defaults on exec.
		2323
		2324	Feel free to install your own handler, or reset it to defaults.
		2325
		2326	=back
		2327
		2328	=cut
		2329
		2330	undef $SIG{CHLD}
		2331	if $SIG{CHLD} eq 'IGNORE';
		2332
		2333	$SIG{PIPE} = sub { }
		2334	unless defined $SIG{PIPE};
		2335
		2336	=head1 RECOMMENDED/OPTIONAL MODULES
		2337
		2338	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2339	it's built-in modules) are required to use it.
		2340
		2341	That does not mean that AnyEvent won't take advantage of some additional
		2342	modules if they are installed.
		2343
		2344	This section epxlains which additional modules will be used, and how they
		2345	affect AnyEvent's operetion.
		2346
		2347	=over 4
		2348
		2349	=item L<Async::Interrupt>
		2350
		2351	This slightly arcane module is used to implement fast signal handling: To
		2352	my knowledge, there is no way to do completely race-free and quick
		2353	signal handling in pure perl. To ensure that signals still get
		2354	delivered, AnyEvent will start an interval timer to wake up perl (and
		2355	catch the signals) with some delay (default is 10 seconds, look for
		2356	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2357
		2358	If this module is available, then it will be used to implement signal
		2359	catching, which means that signals will not be delayed, and the event loop
		2360	will not be interrupted regularly, which is more efficient (And good for
		2361	battery life on laptops).
		2362
		2363	This affects not just the pure-perl event loop, but also other event loops
		2364	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2365
		2366	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2367	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2368	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2369	does nothing for those backends.
		2370
		2371	=item L<EV>
		2372
		2373	This module isn't really "optional", as it is simply one of the backend
		2374	event loops that AnyEvent can use. However, it is simply the best event
		2375	loop available in terms of features, speed and stability: It supports
		2376	the AnyEvent API optimally, implements all the watcher types in XS, does
		2377	automatic timer adjustments even when no monotonic clock is available,
		2378	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2379	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2380	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2381
		2382	=item L<Guard>
		2383
		2384	The guard module, when used, will be used to implement
		2385	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2386	lot less memory), but otherwise doesn't affect guard operation much. It is
		2387	purely used for performance.
		2388
		2389	=item L<JSON> and L<JSON::XS>
		2390
		2391	This module is required when you want to read or write JSON data via
		2392	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2393	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2394
		2395	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2396	installed.
		2397
		2398	=item L<Net::SSLeay>
		2399
		2400	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2401	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2402	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2403
		2404	=item L<Time::HiRes>
		2405
		2406	This module is part of perl since release 5.008. It will be used when the
		2407	chosen event library does not come with a timing source on it's own. The
		2408	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2409	try to use a monotonic clock for timing stability.
		2410
		2411	=back
		2412
1625		2413
1626	=head1 FORK	2414	=head1 FORK
1627		2415
1628	Most event libraries are not fork-safe. The ones who are usually are	2416	Most event libraries are not fork-safe. The ones who are usually are
1629	because they rely on inefficient but fork-safe C<select> or C<poll>	2417	because they rely on inefficient but fork-safe C<select> or C<poll>
1630	calls. Only L<EV> is fully fork-aware.	2418	calls. Only L<EV> is fully fork-aware.
1631		2419
1632	If you have to fork, you must either do so I<before> creating your first	2420	If you have to fork, you must either do so I<before> creating your first
1633	watcher OR you must not use AnyEvent at all in the child.	2421	watcher OR you must not use AnyEvent at all in the child OR you must do
		2422	something completely out of the scope of AnyEvent.
1634		2423
1635		2424
1636	=head1 SECURITY CONSIDERATIONS	2425	=head1 SECURITY CONSIDERATIONS
1637		2426
1638	AnyEvent can be forced to load any event model via	2427	AnyEvent can be forced to load any event model via
…		…
1643	specified in the variable.	2432	specified in the variable.
1644		2433
1645	You can make AnyEvent completely ignore this variable by deleting it	2434	You can make AnyEvent completely ignore this variable by deleting it
1646	before the first watcher gets created, e.g. with a C<BEGIN> block:	2435	before the first watcher gets created, e.g. with a C<BEGIN> block:
1647		2436
1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2437	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1649		2438
1650	use AnyEvent;	2439	use AnyEvent;
1651		2440
1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2441	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1653	be used to probe what backend is used and gain other information (which is	2442	be used to probe what backend is used and gain other information (which is
1654	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2443	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2444	$ENV{PERL_ANYEVENT_STRICT}.
		2445
		2446	Note that AnyEvent will remove I<all> environment variables starting with
		2447	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2448	enabled.
		2449
		2450
		2451	=head1 BUGS
		2452
		2453	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2454	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2455	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2456	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2457	pronounced).
1655		2458
1656		2459
1657	=head1 SEE ALSO	2460	=head1 SEE ALSO
1658		2461
1659	Utility functions: L<AnyEvent::Util>.	2462	Utility functions: L<AnyEvent::Util>.
…		…
1662	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2465	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1663		2466
1664	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2467	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1665	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2468	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1666	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2469	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1667	L<AnyEvent::Impl::POE>.	2470	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1668		2471
1669	Non-blocking file handles, sockets, TCP clients and	2472	Non-blocking file handles, sockets, TCP clients and
1670	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2473	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1671		2474
1672	Asynchronous DNS: L<AnyEvent::DNS>.	2475	Asynchronous DNS: L<AnyEvent::DNS>.
1673		2476
1674	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2477	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2478	L<Coro::Event>,
1675		2479
1676	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2480	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2481	L<AnyEvent::HTTP>.
1677		2482
1678		2483
1679	=head1 AUTHOR	2484	=head1 AUTHOR
1680		2485
1681	Marc Lehmann <schmorp@schmorp.de>	2486	Marc Lehmann <schmorp@schmorp.de>
1682	http://home.schmorp.de/	2487	http://home.schmorp.de/
1683		2488
1684	=cut	2489	=cut
1685		2490
1686	1	2491	1
1687		2492

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