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Revision 1.253 by root, Tue Jul 21 06:00:47 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
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	Respository>, 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 enourmous 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
64	offering the functionality that is necessary, in as thin as a wrapper as	96	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	97	technically possible.
66		98
		99	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		100	of useful functionality, such as an asynchronous DNS resolver, 100%
		101	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		102	such as Windows) and lots of real-world knowledge and workarounds for
		103	platform bugs and differences.
		104
67	Of course, if you want lots of policy (this can arguably be somewhat	105	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	106	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	107	model, you should I<not> use this module.
70		108
71	=head1 DESCRIPTION	109	=head1 DESCRIPTION
72		110
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	140	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	141	use AnyEvent so their modules work together with others seamlessly...
104		142
105	The pure-perl implementation of AnyEvent is called	143	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	144	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	145	explicitly and enjoy the high availability of that event loop :)
108		146
109	=head1 WATCHERS	147	=head1 WATCHERS
110		148
111	AnyEvent has the central concept of a I<watcher>, which is an object that	149	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	150	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	151	the callback to call, the file handle to watch, etc.
114		152
115	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	156	is in control).
119		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
120	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
121	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
122	to it).	166	to it).
123		167
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		172
129	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
130		174
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
133	undef $w;	177	undef $w;
134	});	178	});
135		179
136	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,
137	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
138	declared.	182	declared.
139		183
140	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
141		185
142	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
143	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
144		188
145	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
146	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
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
148	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.
149	becomes ready.
150		200
151	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
154		204
…		…
158		208
159	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	211	handles.
162		212
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	218	warn "read: $input\n";
169	undef $w;	219	undef $w;
170	});	220	});
…		…
180		230
181	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
184		234
185	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
186	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
187	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.
188		240
189	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.
190		244
191	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	248	warn "timeout\n";
194	});	249	});
195		250
196	# to cancel the timer:	251	# to cancel the timer:
197	undef $w;	252	undef $w;
198		253
199	Example 2:
200
201	# 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.
202	my $w;
203		255
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
207	};	258	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		259
212	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
213		261
214	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
215	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
…		…
227	timers.	275	timers.
228		276
229	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	278	AnyEvent API.
231		279
		280	AnyEvent has two additional methods that return the "current time":
		281
		282	=over 4
		283
		284	=item AnyEvent->time
		285
		286	This returns the "current wallclock time" as a fractional number of
		287	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		288	return, and the result is guaranteed to be compatible with those).
		289
		290	It progresses independently of any event loop processing, i.e. each call
		291	will check the system clock, which usually gets updated frequently.
		292
		293	=item AnyEvent->now
		294
		295	This also returns the "current wallclock time", but unlike C<time>, above,
		296	this value might change only once per event loop iteration, depending on
		297	the event loop (most return the same time as C<time>, above). This is the
		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.
		309
		310	For a practical example of when these times differ, consider L<Event::Lib>
		311	and L<EV> and the following set-up:
		312
		313	The event loop is running and has just invoked one of your callback at
		314	time=500 (assume no other callbacks delay processing). In your callback,
		315	you wait a second by executing C<sleep 1> (blocking the process for a
		316	second) and then (at time=501) you create a relative timer that fires
		317	after three seconds.
		318
		319	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		320	both return C<501>, because that is the current time, and the timer will
		321	be scheduled to fire at time=504 (C<501> + C<3>).
		322
		323	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		324	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		325	last event processing phase started. With L<EV>, your timer gets scheduled
		326	to run at time=503 (C<500> + C<3>).
		327
		328	In one sense, L<Event::Lib> is more exact, as it uses the current time
		329	regardless of any delays introduced by event processing. However, most
		330	callbacks do not expect large delays in processing, so this causes a
		331	higher drift (and a lot more system calls to get the current time).
		332
		333	In another sense, L<EV> is more exact, as your timer will be scheduled at
		334	the same time, regardless of how long event processing actually took.
		335
		336	In either case, if you care (and in most cases, you don't), then you
		337	can get whatever behaviour you want with any event loop, by taking the
		338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		339	account.
		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
		356	=back
		357
232	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
233		359
234	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
235	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
236	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
237		363
238	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
241		367
242	Multiple signal occurances can be clumped together into one callback	368	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
246		372
247	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
248	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
249		376
250	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
252		380
253	Example: exit on SIGINT	381	Example: exit on SIGINT
254		382
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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
257	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
258		402
259	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.
260		404
261	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 (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	406	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	407	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	409
266	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
267		418
268	There is a slight catch to child watchers, however: you usually start them	419	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	420	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
271		422
272	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	425	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
275		429
276	This means you cannot create a child watcher as the very first thing in an	430	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	431	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
279		438
280	Example: fork a process and wait for it	439	Example: fork a process and wait for it
281		440
282	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
283		442
284	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
285		444
286	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
287	pid => $pid,	446	pid => $pid,
288	cb => sub {	447	cb => sub {
289	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
291	$done->send;	450	$done->send;
292	},	451	},
293	);	452	);
294		453
295	# do something else, then wait for process exit	454	# do something else, then wait for process exit
296	$done->recv;	455	$done->recv;
		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
297		491
298	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
299		493
300	If you are familiar with some event loops you will know that all of them	494	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	495	require you to run some blocking "loop", "run" or similar function that
302	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
303		497
304	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
305	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
306		500
307	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	502	because they represent a condition that must become true.
		503
		504	Now is probably a good time to look at the examples further below.
309		505
310	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
312	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	509	becomes true, with the condition variable as the first argument (but not
		510	the results).
314		511
315	After creation, the conditon variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method.	513	by calling the C<send> method (or calling the condition variable as if it
		514	were a callback, read about the caveats in the description for the C<<
		515	->send >> method).
317		516
318	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
319	optionally wait for them. They can also be called merge points - points	518	optionally wait for them. They can also be called merge points - points
320	in time where multiple outstandign events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
321	another way to call them is transations - each condition variable can be	520	another way to call them is transactions - each condition variable can be
322	used to represent a transaction, which finishes at some point and delivers	521	used to represent a transaction, which finishes at some point and delivers
323	a result.	522	a result. And yet some people know them as "futures" - a promise to
		523	compute/deliver something that you can wait for.
324		524
325	Condition variables are very useful to signal that something has finished,	525	Condition variables are very useful to signal that something has finished,
326	for example, if you write a module that does asynchronous http requests,	526	for example, if you write a module that does asynchronous http requests,
327	then a condition variable would be the ideal candidate to signal the	527	then a condition variable would be the ideal candidate to signal the
328	availability of results. The user can either act when the callback is	528	availability of results. The user can either act when the callback is
…		…
332	you can block your main program until an event occurs - for example, you	532	you can block your main program until an event occurs - for example, you
333	could C<< ->recv >> in your main program until the user clicks the Quit	533	could C<< ->recv >> in your main program until the user clicks the Quit
334	button of your app, which would C<< ->send >> the "quit" event.	534	button of your app, which would C<< ->send >> the "quit" event.
335		535
336	Note that condition variables recurse into the event loop - if you have	536	Note that condition variables recurse into the event loop - if you have
337	two pieces of code that call C<< ->recv >> in a round-robbin fashion, you	537	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338	lose. Therefore, condition variables are good to export to your caller, but	538	lose. Therefore, condition variables are good to export to your caller, but
339	you should avoid making a blocking wait yourself, at least in callbacks,	539	you should avoid making a blocking wait yourself, at least in callbacks,
340	as this asks for trouble.	540	as this asks for trouble.
341		541
342	Condition variables are represented by hash refs in perl, and the keys	542	Condition variables are represented by hash refs in perl, and the keys
…		…
347		547
348	There are two "sides" to a condition variable - the "producer side" which	548	There are two "sides" to a condition variable - the "producer side" which
349	eventually calls C<< -> send >>, and the "consumer side", which waits	549	eventually calls C<< -> send >>, and the "consumer side", which waits
350	for the send to occur.	550	for the send to occur.
351		551
352	Example:	552	Example: wait for a timer.
353		553
354	# wait till the result is ready	554	# wait till the result is ready
355	my $result_ready = AnyEvent->condvar;	555	my $result_ready = AnyEvent->condvar;
356		556
357	# do something such as adding a timer	557	# do something such as adding a timer
…		…
362	after => 1,	562	after => 1,
363	cb => sub { $result_ready->send },	563	cb => sub { $result_ready->send },
364	);	564	);
365		565
366	# this "blocks" (while handling events) till the callback	566	# this "blocks" (while handling events) till the callback
367	# calls send	567	# calls -<send
368	$result_ready->recv;	568	$result_ready->recv;
		569
		570	Example: wait for a timer, but take advantage of the fact that condition
		571	variables are also callable directly.
		572
		573	my $done = AnyEvent->condvar;
		574	my $delay = AnyEvent->timer (after => 5, cb => $done);
		575	$done->recv;
		576
		577	Example: Imagine an API that returns a condvar and doesn't support
		578	callbacks. This is how you make a synchronous call, for example from
		579	the main program:
		580
		581	use AnyEvent::CouchDB;
		582
		583	...
		584
		585	my @info = $couchdb->info->recv;
		586
		587	And this is how you would just set a callback to be called whenever the
		588	results are available:
		589
		590	$couchdb->info->cb (sub {
		591	my @info = $_[0]->recv;
		592	});
369		593
370	=head3 METHODS FOR PRODUCERS	594	=head3 METHODS FOR PRODUCERS
371		595
372	These methods should only be used by the producing side, i.e. the	596	These methods should only be used by the producing side, i.e. the
373	code/module that eventually sends the signal. Note that it is also	597	code/module that eventually sends the signal. Note that it is also
…		…
386	immediately from within send.	610	immediately from within send.
387		611
388	Any arguments passed to the C<send> call will be returned by all	612	Any arguments passed to the C<send> call will be returned by all
389	future C<< ->recv >> calls.	613	future C<< ->recv >> calls.
390		614
		615	Condition variables are overloaded so one can call them directly (as if
		616	they were a code reference). Calling them directly is the same as calling
		617	C<send>.
		618
391	=item $cv->croak ($error)	619	=item $cv->croak ($error)
392		620
393	Similar to send, but causes all call's to C<< ->recv >> to invoke	621	Similar to send, but causes all call's to C<< ->recv >> to invoke
394	C<Carp::croak> with the given error message/object/scalar.	622	C<Carp::croak> with the given error message/object/scalar.
395		623
396	This can be used to signal any errors to the condition variable	624	This can be used to signal any errors to the condition variable
397	user/consumer.	625	user/consumer. Doing it this way instead of calling C<croak> directly
		626	delays the error detetcion, but has the overwhelmign advantage that it
		627	diagnoses the error at the place where the result is expected, and not
		628	deep in some event clalback without connection to the actual code causing
		629	the problem.
398		630
399	=item $cv->begin ([group callback])	631	=item $cv->begin ([group callback])
400		632
401	=item $cv->end	633	=item $cv->end
402
403	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		634
405	These two methods can be used to combine many transactions/events into	635	These two methods can be used to combine many transactions/events into
406	one. For example, a function that pings many hosts in parallel might want	636	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	637	to use a condition variable for the whole process.
408		638
…		…
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	640	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	641	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->send >>, but that is not required. If no	642	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<send> will be called without any arguments.	643	callback was set, C<send> will be called without any arguments.
414		644
415	Let's clarify this with the ping example:	645	You can think of C<< $cv->send >> giving you an OR condition (one call
		646	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		647	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		648
		649	Let's start with a simple example: you have two I/O watchers (for example,
		650	STDOUT and STDERR for a program), and you want to wait for both streams to
		651	close before activating a condvar:
		652
		653	my $cv = AnyEvent->condvar;
		654
		655	$cv->begin; # first watcher
		656	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		657	defined sysread $fh1, my $buf, 4096
		658	or $cv->end;
		659	});
		660
		661	$cv->begin; # second watcher
		662	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		663	defined sysread $fh2, my $buf, 4096
		664	or $cv->end;
		665	});
		666
		667	$cv->recv;
		668
		669	This works because for every event source (EOF on file handle), there is
		670	one call to C<begin>, so the condvar waits for all calls to C<end> before
		671	sending.
		672
		673	The ping example mentioned above is slightly more complicated, as the
		674	there are results to be passwd back, and the number of tasks that are
		675	begung can potentially be zero:
416		676
417	my $cv = AnyEvent->condvar;	677	my $cv = AnyEvent->condvar;
418		678
419	my %result;	679	my %result;
420	$cv->begin (sub { $cv->send (\%result) });	680	$cv->begin (sub { $cv->send (\%result) });
…		…
440	loop, which serves two important purposes: first, it sets the callback	700	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	701	to be called once the counter reaches C<0>, and second, it ensures that
442	C<send> is called even when C<no> hosts are being pinged (the loop	702	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	703	doesn't execute once).
444		704
445	This is the general pattern when you "fan out" into multiple subrequests:	705	This is the general pattern when you "fan out" into multiple (but
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	706	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
447	is called at least once, and then, for each subrequest you start, call	707	the callback and ensure C<end> is called at least once, and then, for each
448	C<begin> and for eahc subrequest you finish, call C<end>.	708	subrequest you start, call C<begin> and for each subrequest you finish,
		709	call C<end>.
449		710
450	=back	711	=back
451		712
452	=head3 METHODS FOR CONSUMERS	713	=head3 METHODS FOR CONSUMERS
453		714
…		…
469	function will call C<croak>.	730	function will call C<croak>.
470		731
471	In list context, all parameters passed to C<send> will be returned,	732	In list context, all parameters passed to C<send> will be returned,
472	in scalar context only the first one will be returned.	733	in scalar context only the first one will be returned.
473		734
		735	Note that doing a blocking wait in a callback is not supported by any
		736	event loop, that is, recursive invocation of a blocking C<< ->recv
		737	>> is not allowed, and the C<recv> call will C<croak> if such a
		738	condition is detected. This condition can be slightly loosened by using
		739	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		740	any thread that doesn't run the event loop itself.
		741
474	Not all event models support a blocking wait - some die in that case	742	Not all event models support a blocking wait - some die in that case
475	(programs might want to do that to stay interactive), so I<if you are	743	(programs might want to do that to stay interactive), so I<if you are
476	using this from a module, never require a blocking wait>, but let the	744	using this from a module, never require a blocking wait>. Instead, let the
477	caller decide whether the call will block or not (for example, by coupling	745	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	746	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	747	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	748	while still supporting blocking waits if the caller so desires).
481
482	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.
486
487	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489	versions and also integrates coroutines into AnyEvent, making blocking
490	C<< ->recv >> calls perfectly safe as long as they are done from another
491	coroutine (one that doesn't run the event loop).
492		749
493	You can ensure that C<< -recv >> never blocks by setting a callback and	750	You can ensure that C<< -recv >> never blocks by setting a callback and
494	only calling C<< ->recv >> from within that callback (or at a later	751	only calling C<< ->recv >> from within that callback (or at a later
495	time). This will work even when the event loop does not support blocking	752	time). This will work even when the event loop does not support blocking
496	waits otherwise.	753	waits otherwise.
…		…
498	=item $bool = $cv->ready	755	=item $bool = $cv->ready
499		756
500	Returns true when the condition is "true", i.e. whether C<send> or	757	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	758	C<croak> have been called.
502		759
503	=item $cb = $cv->cb ([new callback])	760	=item $cb = $cv->cb ($cb->($cv))
504		761
505	This is a mutator function that returns the callback set and optionally	762	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	763	replaces it before doing so.
507		764
508	The callback will be called when the condition becomes "true", i.e. when	765	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<recv> inside the callback	766	C<send> or C<croak> are called, with the only argument being the condition
510	or at any later time is guaranteed not to block.	767	variable itself. Calling C<recv> inside the callback or at any later time
		768	is guaranteed not to block.
511		769
512	=back	770	=back
513		771
		772	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		773
		774	The available backend classes are (every class has its own manpage):
		775
		776	=over 4
		777
		778	=item Backends that are autoprobed when no other event loop can be found.
		779
		780	EV is the preferred backend when no other event loop seems to be in
		781	use. If EV is not installed, then AnyEvent will try Event, and, failing
		782	that, will fall back to its own pure-perl implementation, which is
		783	available everywhere as it comes with AnyEvent itself.
		784
		785	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		786	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		787	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		788
		789	=item Backends that are transparently being picked up when they are used.
		790
		791	These will be used when they are currently loaded when the first watcher
		792	is created, in which case it is assumed that the application is using
		793	them. This means that AnyEvent will automatically pick the right backend
		794	when the main program loads an event module before anything starts to
		795	create watchers. Nothing special needs to be done by the main program.
		796
		797	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		798	AnyEvent::Impl::Tk based on Tk, very broken.
		799	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		800	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		801
		802	=item Backends with special needs.
		803
		804	Qt requires the Qt::Application to be instantiated first, but will
		805	otherwise be picked up automatically. As long as the main program
		806	instantiates the application before any AnyEvent watchers are created,
		807	everything should just work.
		808
		809	AnyEvent::Impl::Qt based on Qt.
		810
		811	Support for IO::Async can only be partial, as it is too broken and
		812	architecturally limited to even support the AnyEvent API. It also
		813	is the only event loop that needs the loop to be set explicitly, so
		814	it can only be used by a main program knowing about AnyEvent. See
		815	L<AnyEvent::Impl::Async> for the gory details.
		816
		817	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		818
		819	=item Event loops that are indirectly supported via other backends.
		820
		821	Some event loops can be supported via other modules:
		822
		823	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		824
		825	B<WxWidgets> has no support for watching file handles. However, you can
		826	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		827	polls 20 times per second, which was considered to be too horrible to even
		828	consider for AnyEvent.
		829
		830	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		831	backend, so it can be supported through POE.
		832
		833	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		834	load L<POE> when detecting them, in the hope that POE will pick them up,
		835	in which case everything will be automatic.
		836
		837	=back
		838
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
516	=over 4	844	=over 4
517		845
518	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
519		847
520	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
521	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
522	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
523	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
524	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
525		855	will be C<urxvt::anyevent>).
526	The known classes so far are:
527
528	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
529	AnyEvent::Impl::Event based on Event, second best choice.
530	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
531	AnyEvent::Impl::Glib based on Glib, third-best choice.
532	AnyEvent::Impl::Tk based on Tk, very bad choice.
533	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
534	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
535	AnyEvent::Impl::POE based on POE, not generic enough for full support.
536
537	There is no support for WxWidgets, as WxWidgets has no support for
538	watching file handles. However, you can use WxWidgets through the
539	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
540	second, which was considered to be too horrible to even consider for
541	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
542	it's adaptor.
543
544	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
545	autodetecting them.
546		856
547	=item AnyEvent::detect	857	=item AnyEvent::detect
548		858
549	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550	if necessary. You should only call this function right before you would	860	if necessary. You should only call this function right before you would
551	have created an AnyEvent watcher anyway, that is, as late as possible at	861	have created an AnyEvent watcher anyway, that is, as late as possible at
552	runtime.	862	runtime, and not e.g. while initialising of your module.
		863
		864	If you need to do some initialisation before AnyEvent watchers are
		865	created, use C<post_detect>.
553		866
554	=item $guard = AnyEvent::post_detect { BLOCK }	867	=item $guard = AnyEvent::post_detect { BLOCK }
555		868
556	Arranges for the code block to be executed as soon as the event model is	869	Arranges for the code block to be executed as soon as the event model is
557	autodetected (or immediately if this has already happened).	870	autodetected (or immediately if this has already happened).
558		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		874	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		875	other initialisations - see the sources of L<AnyEvent::Strict> or
		876	L<AnyEvent::AIO> to see how this is used.
		877
		878	The most common usage is to create some global watchers, without forcing
		879	event module detection too early, for example, L<AnyEvent::AIO> creates
		880	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		881	avoid autodetecting the event module at load time.
		882
559	If called in scalar or list context, then it creates and returns an object	883	If called in scalar or list context, then it creates and returns an object
560	that automatically removes the callback again when it is destroyed. See	884	that automatically removes the callback again when it is destroyed (or
		885	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
561	L<Coro::BDB> for a case where this is useful.	886	a case where this is useful.
		887
		888	Example: Create a watcher for the IO::AIO module and store it in
		889	C<$WATCHER>. Only do so after the event loop is initialised, though.
		890
		891	our WATCHER;
		892
		893	my $guard = AnyEvent::post_detect {
		894	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		895	};
		896
		897	# the ||= is important in case post_detect immediately runs the block,
		898	# as to not clobber the newly-created watcher. assigning both watcher and
		899	# post_detect guard to the same variable has the advantage of users being
		900	# able to just C<undef $WATCHER> if the watcher causes them grief.
		901
		902	$WATCHER ||= $guard;
562		903
563	=item @AnyEvent::post_detect	904	=item @AnyEvent::post_detect
564		905
565	If there are any code references in this array (you can C<push> to it	906	If there are any code references in this array (you can C<push> to it
566	before or after loading AnyEvent), then they will called directly after	907	before or after loading AnyEvent), then they will called directly after
567	the event loop has been chosen.	908	the event loop has been chosen.
568		909
569	You should check C<$AnyEvent::MODEL> before adding to this array, though:	910	You should check C<$AnyEvent::MODEL> before adding to this array, though:
570	if it contains a true value then the event loop has already been detected,	911	if it is defined then the event loop has already been detected, and the
571	and the array will be ignored.	912	array will be ignored.
572		913
573	Best use C<AnyEvent::post_detect { BLOCK }> instead.	914	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		915	it,as it takes care of these details.
		916
		917	This variable is mainly useful for modules that can do something useful
		918	when AnyEvent is used and thus want to know when it is initialised, but do
		919	not need to even load it by default. This array provides the means to hook
		920	into AnyEvent passively, without loading it.
574		921
575	=back	922	=back
576		923
577	=head1 WHAT TO DO IN A MODULE	924	=head1 WHAT TO DO IN A MODULE
578		925
…		…
601		948
602	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	949	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
603	do anything special (it does not need to be event-based) and let AnyEvent	950	do anything special (it does not need to be event-based) and let AnyEvent
604	decide which implementation to chose if some module relies on it.	951	decide which implementation to chose if some module relies on it.
605		952
606	If the main program relies on a specific event model. For example, in	953	If the main program relies on a specific event model - for example, in
607	Gtk2 programs you have to rely on the Glib module. You should load the	954	Gtk2 programs you have to rely on the Glib module - you should load the
608	event module before loading AnyEvent or any module that uses it: generally	955	event module before loading AnyEvent or any module that uses it: generally
609	speaking, you should load it as early as possible. The reason is that	956	speaking, you should load it as early as possible. The reason is that
610	modules might create watchers when they are loaded, and AnyEvent will	957	modules might create watchers when they are loaded, and AnyEvent will
611	decide on the event model to use as soon as it creates watchers, and it	958	decide on the event model to use as soon as it creates watchers, and it
612	might chose the wrong one unless you load the correct one yourself.	959	might chose the wrong one unless you load the correct one yourself.
613		960
614	You can chose to use a rather inefficient pure-perl implementation by	961	You can chose to use a pure-perl implementation by loading the
615	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	962	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616	behaviour everywhere, but letting AnyEvent chose is generally better.	963	everywhere, but letting AnyEvent chose the model is generally better.
		964
		965	=head2 MAINLOOP EMULATION
		966
		967	Sometimes (often for short test scripts, or even standalone programs who
		968	only want to use AnyEvent), you do not want to run a specific event loop.
		969
		970	In that case, you can use a condition variable like this:
		971
		972	AnyEvent->condvar->recv;
		973
		974	This has the effect of entering the event loop and looping forever.
		975
		976	Note that usually your program has some exit condition, in which case
		977	it is better to use the "traditional" approach of storing a condition
		978	variable somewhere, waiting for it, and sending it when the program should
		979	exit cleanly.
		980
617		981
618	=head1 OTHER MODULES	982	=head1 OTHER MODULES
619		983
620	The following is a non-exhaustive list of additional modules that use	984	The following is a non-exhaustive list of additional modules that use
621	AnyEvent and can therefore be mixed easily with other AnyEvent modules	985	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
622	in the same program. Some of the modules come with AnyEvent, some are	986	modules and other event loops in the same program. Some of the modules
623	available via CPAN.	987	come with AnyEvent, most are available via CPAN.
624		988
625	=over 4	989	=over 4
626		990
627	=item L<AnyEvent::Util>	991	=item L<AnyEvent::Util>
628		992
629	Contains various utility functions that replace often-used but blocking	993	Contains various utility functions that replace often-used but blocking
630	functions such as C<inet_aton> by event-/callback-based versions.	994	functions such as C<inet_aton> by event-/callback-based versions.
631		995
		996	=item L<AnyEvent::Socket>
		997
		998	Provides various utility functions for (internet protocol) sockets,
		999	addresses and name resolution. Also functions to create non-blocking tcp
		1000	connections or tcp servers, with IPv6 and SRV record support and more.
		1001
632	=item L<AnyEvent::Handle>	1002	=item L<AnyEvent::Handle>
633		1003
634	Provide read and write buffers and manages watchers for reads and writes.	1004	Provide read and write buffers, manages watchers for reads and writes,
		1005	supports raw and formatted I/O, I/O queued and fully transparent and
		1006	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1007
		1008	=item L<AnyEvent::DNS>
		1009
		1010	Provides rich asynchronous DNS resolver capabilities.
		1011
		1012	=item L<AnyEvent::HTTP>
		1013
		1014	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1015	HTTP requests.
635		1016
636	=item L<AnyEvent::HTTPD>	1017	=item L<AnyEvent::HTTPD>
637		1018
638	Provides a simple web application server framework.	1019	Provides a simple web application server framework.
639		1020
640	=item L<AnyEvent::DNS>
641
642	Provides asynchronous DNS resolver capabilities, beyond what
643	L<AnyEvent::Util> offers.
644
645	=item L<AnyEvent::FastPing>	1021	=item L<AnyEvent::FastPing>
646		1022
647	The fastest ping in the west.	1023	The fastest ping in the west.
648		1024
		1025	=item L<AnyEvent::DBI>
		1026
		1027	Executes L<DBI> requests asynchronously in a proxy process.
		1028
		1029	=item L<AnyEvent::AIO>
		1030
		1031	Truly asynchronous I/O, should be in the toolbox of every event
		1032	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1033	together.
		1034
		1035	=item L<AnyEvent::BDB>
		1036
		1037	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1038	L<BDB> and AnyEvent together.
		1039
		1040	=item L<AnyEvent::GPSD>
		1041
		1042	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1043
649	=item L<Net::IRC3>	1044	=item L<AnyEvent::IRC>
650		1045
651	AnyEvent based IRC client module family.	1046	AnyEvent based IRC client module family (replacing the older Net::IRC3).
652		1047
653	=item L<Net::XMPP2>	1048	=item L<AnyEvent::XMPP>
654		1049
655	AnyEvent based XMPP (Jabber protocol) module family.	1050	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1051	Net::XMPP2>.
		1052
		1053	=item L<AnyEvent::IGS>
		1054
		1055	A non-blocking interface to the Internet Go Server protocol (used by
		1056	L<App::IGS>).
656		1057
657	=item L<Net::FCP>	1058	=item L<Net::FCP>
658		1059
659	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1060	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
660	of AnyEvent.	1061	of AnyEvent.
…		…
665		1066
666	=item L<Coro>	1067	=item L<Coro>
667		1068
668	Has special support for AnyEvent via L<Coro::AnyEvent>.	1069	Has special support for AnyEvent via L<Coro::AnyEvent>.
669		1070
670	=item L<AnyEvent::AIO>, L<IO::AIO>
671
672	Truly asynchronous I/O, should be in the toolbox of every event
673	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
674	together.
675
676	=item L<AnyEvent::BDB>, L<BDB>
677
678	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
679	IO::AIO and AnyEvent together.
680
681	=item L<IO::Lambda>
682
683	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
684
685	=back	1071	=back
686		1072
687	=cut	1073	=cut
688		1074
689	package AnyEvent;	1075	package AnyEvent;
690		1076
		1077	# basically a tuned-down version of common::sense
		1078	sub common_sense {
691	no warnings;	1079	# no warnings
692	use strict;	1080	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1081	# use strict vars subs
		1082	$^H |= 0x00000600;
		1083	}
693		1084
		1085	BEGIN { AnyEvent::common_sense }
		1086
694	use Carp;	1087	use Carp ();
695		1088
696	our $VERSION = '3.41';	1089	our $VERSION = 4.86;
697	our $MODEL;	1090	our $MODEL;
698		1091
699	our $AUTOLOAD;	1092	our $AUTOLOAD;
700	our @ISA;	1093	our @ISA;
701		1094
702	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
703
704	our @REGISTRY;	1095	our @REGISTRY;
		1096
		1097	our $WIN32;
		1098
		1099	our $VERBOSE;
		1100
		1101	BEGIN {
		1102	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1103	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1104
		1105	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1106	if ${^TAINT};
		1107
		1108	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1109
		1110	}
		1111
		1112	our $MAX_SIGNAL_LATENCY = 10;
		1113
		1114	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1115
		1116	{
		1117	my $idx;
		1118	$PROTOCOL{$_} = ++$idx
		1119	for reverse split /\s*,\s*/,
		1120	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1121	}
705		1122
706	my @models = (	1123	my @models = (
707	[EV:: => AnyEvent::Impl::EV::],	1124	[EV:: => AnyEvent::Impl::EV::],
708	[Event:: => AnyEvent::Impl::Event::],	1125	[Event:: => AnyEvent::Impl::Event::],
		1126	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1127	# everything below here will not be autoprobed
		1128	# as the pureperl backend should work everywhere
		1129	# and is usually faster
		1130	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1131	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
709	[Tk:: => AnyEvent::Impl::Tk::],	1132	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1133	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1134	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
710	[Wx:: => AnyEvent::Impl::POE::],	1135	[Wx:: => AnyEvent::Impl::POE::],
711	[Prima:: => AnyEvent::Impl::POE::],	1136	[Prima:: => AnyEvent::Impl::POE::],
712	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1137	# IO::Async is just too broken - we would need workarounds for its
713	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1138	# byzantine signal and broken child handling, among others.
714	[Glib:: => AnyEvent::Impl::Glib::],	1139	# IO::Async is rather hard to detect, as it doesn't have any
715	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1140	# obvious default class.
716	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1141	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
717	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1142	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1143	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
718	);	1144	);
719		1145
720	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1146	our %method = map +($_ => 1),
		1147	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
721		1148
722	our @post_detect;	1149	our @post_detect;
723		1150
724	sub post_detect(&) {	1151	sub post_detect(&) {
725	my ($cb) = @_;	1152	my ($cb) = @_;
726		1153
727	if ($MODEL) {	1154	if ($MODEL) {
728	$cb->();	1155	$cb->();
729		1156
730	1	1157	undef
731	} else {	1158	} else {
732	push @post_detect, $cb;	1159	push @post_detect, $cb;
733		1160
734	defined wantarray	1161	defined wantarray
735	? bless \$cb, "AnyEvent::Util::Guard"	1162	? bless \$cb, "AnyEvent::Util::postdetect"
736	: ()	1163	: ()
737	}	1164	}
738	}	1165	}
739		1166
740	sub AnyEvent::Util::Guard::DESTROY {	1167	sub AnyEvent::Util::postdetect::DESTROY {
741	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1168	@post_detect = grep $_ != ${$_[0]}, @post_detect;
742	}	1169	}
743		1170
744	sub detect() {	1171	sub detect() {
745	unless ($MODEL) {	1172	unless ($MODEL) {
746	no strict 'refs';	1173	local $SIG{__DIE__};
747		1174
748	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1175	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
749	my $model = "AnyEvent::Impl::$1";	1176	my $model = "AnyEvent::Impl::$1";
750	if (eval "require $model") {	1177	if (eval "require $model") {
751	$MODEL = $model;	1178	$MODEL = $model;
752	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1179	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
753	} else {	1180	} else {
754	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1181	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
755	}	1182	}
756	}	1183	}
757		1184
758	# check for already loaded models	1185	# check for already loaded models
759	unless ($MODEL) {	1186	unless ($MODEL) {
760	for (@REGISTRY, @models) {	1187	for (@REGISTRY, @models) {
761	my ($package, $model) = @$_;	1188	my ($package, $model) = @$_;
762	if (${"$package\::VERSION"} > 0) {	1189	if (${"$package\::VERSION"} > 0) {
763	if (eval "require $model") {	1190	if (eval "require $model") {
764	$MODEL = $model;	1191	$MODEL = $model;
765	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1192	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
766	last;	1193	last;
767	}	1194	}
768	}	1195	}
769	}	1196	}
770		1197
…		…
775	my ($package, $model) = @$_;	1202	my ($package, $model) = @$_;
776	if (eval "require $package"	1203	if (eval "require $package"
777	and ${"$package\::VERSION"} > 0	1204	and ${"$package\::VERSION"} > 0
778	and eval "require $model") {	1205	and eval "require $model") {
779	$MODEL = $model;	1206	$MODEL = $model;
780	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1207	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
781	last;	1208	last;
782	}	1209	}
783	}	1210	}
784		1211
785	$MODEL	1212	$MODEL
786	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1213	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
787	}	1214	}
788	}	1215	}
789		1216
		1217	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1218
790	unshift @ISA, $MODEL;	1219	unshift @ISA, $MODEL;
791	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1220
		1221	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
792		1222
793	(shift @post_detect)->() while @post_detect;	1223	(shift @post_detect)->() while @post_detect;
794	}	1224	}
795		1225
796	$MODEL	1226	$MODEL
…		…
798		1228
799	sub AUTOLOAD {	1229	sub AUTOLOAD {
800	(my $func = $AUTOLOAD) =~ s/.*://;	1230	(my $func = $AUTOLOAD) =~ s/.*://;
801		1231
802	$method{$func}	1232	$method{$func}
803	or croak "$func: not a valid method for AnyEvent objects";	1233	or Carp::croak "$func: not a valid method for AnyEvent objects";
804		1234
805	detect unless $MODEL;	1235	detect unless $MODEL;
806		1236
807	my $class = shift;	1237	my $class = shift;
808	$class->$func (@_);	1238	$class->$func (@_);
809	}	1239	}
810		1240
		1241	# utility function to dup a filehandle. this is used by many backends
		1242	# to support binding more than one watcher per filehandle (they usually
		1243	# allow only one watcher per fd, so we dup it to get a different one).
		1244	sub _dupfh($$;$$) {
		1245	my ($poll, $fh, $r, $w) = @_;
		1246
		1247	# cygwin requires the fh mode to be matching, unix doesn't
		1248	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1249
		1250	open my $fh2, $mode, $fh
		1251	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1252
		1253	# we assume CLOEXEC is already set by perl in all important cases
		1254
		1255	($fh2, $rw)
		1256	}
		1257
811	package AnyEvent::Base;	1258	package AnyEvent::Base;
812		1259
		1260	# default implementations for many methods
		1261
		1262	sub _time {
		1263	# probe for availability of Time::HiRes
		1264	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1265	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1266	*_time = \&Time::HiRes::time;
		1267	# if (eval "use POSIX (); (POSIX::times())...
		1268	} else {
		1269	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1270	*_time = sub { time }; # epic fail
		1271	}
		1272
		1273	&_time
		1274	}
		1275
		1276	sub time { _time }
		1277	sub now { _time }
		1278	sub now_update { }
		1279
813	# default implementation for ->condvar	1280	# default implementation for ->condvar
814		1281
815	sub condvar {	1282	sub condvar {
816	bless {}, AnyEvent::CondVar::	1283	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
817	}	1284	}
818		1285
819	# default implementation for ->signal	1286	# default implementation for ->signal
820		1287
821	our %SIG_CB;	1288	our $HAVE_ASYNC_INTERRUPT;
		1289	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1290	our (%SIG_ASY, %SIG_ASY_W);
		1291	our ($SIG_COUNT, $SIG_TW);
822		1292
		1293	sub _signal_exec {
		1294	$HAVE_ASYNC_INTERRUPT
		1295	? $SIGPIPE_R->drain
		1296	: sysread $SIGPIPE_R, my $dummy, 9;
		1297
		1298	while (%SIG_EV) {
		1299	for (keys %SIG_EV) {
		1300	delete $SIG_EV{$_};
		1301	$_->() for values %{ $SIG_CB{$_} || {} };
		1302	}
		1303	}
		1304	}
		1305
		1306	# install a dumym wakeupw atcher to reduce signal catching latency
		1307	sub _sig_add() {
		1308	unless ($SIG_COUNT++) {
		1309	# try to align timer on a full-second boundary, if possible
		1310	my $NOW = AnyEvent->now;
		1311
		1312	$SIG_TW = AnyEvent->timer (
		1313	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1314	interval => $MAX_SIGNAL_LATENCY,
		1315	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1316	);
		1317	}
		1318	}
		1319
		1320	sub _sig_del {
		1321	undef $SIG_TW
		1322	unless --$SIG_COUNT;
		1323	}
		1324
823	sub signal {	1325	sub _signal {
824	my (undef, %arg) = @_;	1326	my (undef, %arg) = @_;
825		1327
826	my $signal = uc $arg{signal}	1328	my $signal = uc $arg{signal}
827	or Carp::croak "required option 'signal' is missing";	1329	or Carp::croak "required option 'signal' is missing";
828		1330
829	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1331	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1332
		1333	if ($HAVE_ASYNC_INTERRUPT) {
		1334	# async::interrupt
		1335
		1336	$SIG_ASY{$signal} ||= do {
		1337	my $asy = new Async::Interrupt
		1338	cb => sub { undef $SIG_EV{$signal} },
		1339	signal => $signal,
		1340	pipe => [$SIGPIPE_R->filenos],
		1341	;
		1342	$asy->pipe_autodrain (0);
		1343
		1344	$asy
		1345	};
		1346
		1347	} else {
		1348	# pure perl
		1349
830	$SIG{$signal} ||= sub {	1350	$SIG{$signal} ||= sub {
831	$_->() for values %{ $SIG_CB{$signal} || {} };	1351	local $!;
		1352	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1353	undef $SIG_EV{$signal};
		1354	};
		1355
		1356	# can't do signal processing without introducing races in pure perl,
		1357	# so limit the signal latency.
		1358	_sig_add;
832	};	1359	}
833		1360
834	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1361	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
835	}	1362	}
836		1363
		1364	sub signal {
		1365	# probe for availability of Async::Interrupt
		1366	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1367	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1368
		1369	$HAVE_ASYNC_INTERRUPT = 1;
		1370	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1372
		1373	} else {
		1374	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1375
		1376	require Fcntl;
		1377
		1378	if (AnyEvent::WIN32) {
		1379	require AnyEvent::Util;
		1380
		1381	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1382	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1383	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1384	} else {
		1385	pipe $SIGPIPE_R, $SIGPIPE_W;
		1386	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1387	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1388
		1389	# not strictly required, as $^F is normally 2, but let's make sure...
		1390	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1391	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1392	}
		1393
		1394	$SIGPIPE_R
		1395	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1396
		1397	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1398	}
		1399
		1400	*signal = \&_signal;
		1401	&signal
		1402	}
		1403
837	sub AnyEvent::Base::Signal::DESTROY {	1404	sub AnyEvent::Base::signal::DESTROY {
838	my ($signal, $cb) = @{$_[0]};	1405	my ($signal, $cb) = @{$_[0]};
839		1406
		1407	_sig_del;
		1408
840	delete $SIG_CB{$signal}{$cb};	1409	delete $SIG_CB{$signal}{$cb};
841		1410
842	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1411	$HAVE_ASYNC_INTERRUPT
		1412	? delete $SIG_ASY{$signal}
		1413	: # delete doesn't work with older perls - they then
		1414	# print weird messages, or just unconditionally exit
		1415	# instead of getting the default action.
		1416	undef $SIG{$signal}
		1417	unless keys %{ $SIG_CB{$signal} };
843	}	1418	}
844		1419
845	# default implementation for ->child	1420	# default implementation for ->child
846		1421
847	our %PID_CB;	1422	our %PID_CB;
848	our $CHLD_W;	1423	our $CHLD_W;
849	our $CHLD_DELAY_W;	1424	our $CHLD_DELAY_W;
850	our $PID_IDLE;
851	our $WNOHANG;	1425	our $WNOHANG;
852		1426
853	sub _child_wait {	1427	sub _sigchld {
854	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1428	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1429	$_->($pid, $?)
855	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1430	for values %{ $PID_CB{$pid} || {} },
856	(values %{ $PID_CB{0} || {} });	1431	values %{ $PID_CB{0} || {} };
857	}	1432	}
858
859	undef $PID_IDLE;
860	}
861
862	sub _sigchld {
863	# make sure we deliver these changes "synchronous" with the event loop.
864	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
865	undef $CHLD_DELAY_W;
866	&_child_wait;
867	});
868	}	1433	}
869		1434
870	sub child {	1435	sub child {
871	my (undef, %arg) = @_;	1436	my (undef, %arg) = @_;
872		1437
873	defined (my $pid = $arg{pid} + 0)	1438	defined (my $pid = $arg{pid} + 0)
874	or Carp::croak "required option 'pid' is missing";	1439	or Carp::croak "required option 'pid' is missing";
875		1440
876	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1441	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
877		1442
878	unless ($WNOHANG) {	1443	# WNOHANG is almost cetrainly 1 everywhere
879	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1444	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
880	}	1445	? 1
		1446	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
881		1447
882	unless ($CHLD_W) {	1448	unless ($CHLD_W) {
883	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1449	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
884	# child could be a zombie already, so make at least one round	1450	# child could be a zombie already, so make at least one round
885	&_sigchld;	1451	&_sigchld;
886	}	1452	}
887		1453
888	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1454	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
889	}	1455	}
890		1456
891	sub AnyEvent::Base::Child::DESTROY {	1457	sub AnyEvent::Base::child::DESTROY {
892	my ($pid, $cb) = @{$_[0]};	1458	my ($pid, $cb) = @{$_[0]};
893		1459
894	delete $PID_CB{$pid}{$cb};	1460	delete $PID_CB{$pid}{$cb};
895	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1461	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
896		1462
897	undef $CHLD_W unless keys %PID_CB;	1463	undef $CHLD_W unless keys %PID_CB;
898	}	1464	}
899		1465
		1466	# idle emulation is done by simply using a timer, regardless
		1467	# of whether the process is idle or not, and not letting
		1468	# the callback use more than 50% of the time.
		1469	sub idle {
		1470	my (undef, %arg) = @_;
		1471
		1472	my ($cb, $w, $rcb) = $arg{cb};
		1473
		1474	$rcb = sub {
		1475	if ($cb) {
		1476	$w = _time;
		1477	&$cb;
		1478	$w = _time - $w;
		1479
		1480	# never use more then 50% of the time for the idle watcher,
		1481	# within some limits
		1482	$w = 0.0001 if $w < 0.0001;
		1483	$w = 5 if $w > 5;
		1484
		1485	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1486	} else {
		1487	# clean up...
		1488	undef $w;
		1489	undef $rcb;
		1490	}
		1491	};
		1492
		1493	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1494
		1495	bless \\$cb, "AnyEvent::Base::idle"
		1496	}
		1497
		1498	sub AnyEvent::Base::idle::DESTROY {
		1499	undef $${$_[0]};
		1500	}
		1501
900	package AnyEvent::CondVar;	1502	package AnyEvent::CondVar;
901		1503
902	our @ISA = AnyEvent::CondVar::Base::;	1504	our @ISA = AnyEvent::CondVar::Base::;
903		1505
904	package AnyEvent::CondVar::Base;	1506	package AnyEvent::CondVar::Base;
		1507
		1508	#use overload
		1509	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1510	# fallback => 1;
		1511
		1512	# save 300+ kilobytes by dirtily hardcoding overloading
		1513	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1514	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1515	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1516	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1517
		1518	our $WAITING;
905		1519
906	sub _send {	1520	sub _send {
907	# nop	1521	# nop
908	}	1522	}
909		1523
…		…
922	sub ready {	1536	sub ready {
923	$_[0]{_ae_sent}	1537	$_[0]{_ae_sent}
924	}	1538	}
925		1539
926	sub _wait {	1540	sub _wait {
		1541	$WAITING
		1542	and !$_[0]{_ae_sent}
		1543	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1544
		1545	local $WAITING = 1;
927	AnyEvent->one_event while !$_[0]{_ae_sent};	1546	AnyEvent->one_event while !$_[0]{_ae_sent};
928	}	1547	}
929		1548
930	sub recv {	1549	sub recv {
931	$_[0]->_wait;	1550	$_[0]->_wait;
…		…
944	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1563	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
945	}	1564	}
946		1565
947	sub end {	1566	sub end {
948	return if --$_[0]{_ae_counter};	1567	return if --$_[0]{_ae_counter};
949	&{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb};	1568	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
950	}	1569	}
951		1570
952	# undocumented/compatibility with pre-3.4	1571	# undocumented/compatibility with pre-3.4
953	*broadcast = \&send;	1572	*broadcast = \&send;
954	*wait = \&_wait;	1573	*wait = \&_wait;
		1574
		1575	=head1 ERROR AND EXCEPTION HANDLING
		1576
		1577	In general, AnyEvent does not do any error handling - it relies on the
		1578	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1579	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1580	checking of all AnyEvent methods, however, which is highly useful during
		1581	development.
		1582
		1583	As for exception handling (i.e. runtime errors and exceptions thrown while
		1584	executing a callback), this is not only highly event-loop specific, but
		1585	also not in any way wrapped by this module, as this is the job of the main
		1586	program.
		1587
		1588	The pure perl event loop simply re-throws the exception (usually
		1589	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1590	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1591	so on.
		1592
		1593	=head1 ENVIRONMENT VARIABLES
		1594
		1595	The following environment variables are used by this module or its
		1596	submodules.
		1597
		1598	Note that AnyEvent will remove I<all> environment variables starting with
		1599	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1600	enabled.
		1601
		1602	=over 4
		1603
		1604	=item C<PERL_ANYEVENT_VERBOSE>
		1605
		1606	By default, AnyEvent will be completely silent except in fatal
		1607	conditions. You can set this environment variable to make AnyEvent more
		1608	talkative.
		1609
		1610	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1611	conditions, such as not being able to load the event model specified by
		1612	C<PERL_ANYEVENT_MODEL>.
		1613
		1614	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1615	model it chooses.
		1616
		1617	When set to C<8> or higher, then AnyEvent will report extra information on
		1618	which optional modules it loads and how it implements certain features.
		1619
		1620	=item C<PERL_ANYEVENT_STRICT>
		1621
		1622	AnyEvent does not do much argument checking by default, as thorough
		1623	argument checking is very costly. Setting this variable to a true value
		1624	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1625	check the arguments passed to most method calls. If it finds any problems,
		1626	it will croak.
		1627
		1628	In other words, enables "strict" mode.
		1629
		1630	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1631	>>, it is definitely recommended to keep it off in production. Keeping
		1632	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1633	can be very useful, however.
		1634
		1635	=item C<PERL_ANYEVENT_MODEL>
		1636
		1637	This can be used to specify the event model to be used by AnyEvent, before
		1638	auto detection and -probing kicks in. It must be a string consisting
		1639	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1640	and the resulting module name is loaded and if the load was successful,
		1641	used as event model. If it fails to load AnyEvent will proceed with
		1642	auto detection and -probing.
		1643
		1644	This functionality might change in future versions.
		1645
		1646	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1647	could start your program like this:
		1648
		1649	PERL_ANYEVENT_MODEL=Perl perl ...
		1650
		1651	=item C<PERL_ANYEVENT_PROTOCOLS>
		1652
		1653	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1654	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1655	of auto probing).
		1656
		1657	Must be set to a comma-separated list of protocols or address families,
		1658	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1659	used, and preference will be given to protocols mentioned earlier in the
		1660	list.
		1661
		1662	This variable can effectively be used for denial-of-service attacks
		1663	against local programs (e.g. when setuid), although the impact is likely
		1664	small, as the program has to handle conenction and other failures anyways.
		1665
		1666	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1667	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1668	- only support IPv4, never try to resolve or contact IPv6
		1669	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1670	IPv6, but prefer IPv6 over IPv4.
		1671
		1672	=item C<PERL_ANYEVENT_EDNS0>
		1673
		1674	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1675	for DNS. This extension is generally useful to reduce DNS traffic, but
		1676	some (broken) firewalls drop such DNS packets, which is why it is off by
		1677	default.
		1678
		1679	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1680	EDNS0 in its DNS requests.
		1681
		1682	=item C<PERL_ANYEVENT_MAX_FORKS>
		1683
		1684	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1685	will create in parallel.
		1686
		1687	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1688
		1689	The default value for the C<max_outstanding> parameter for the default DNS
		1690	resolver - this is the maximum number of parallel DNS requests that are
		1691	sent to the DNS server.
		1692
		1693	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1694
		1695	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1696	configuration) in the default resolver. When set to the empty string, no
		1697	default config will be used.
		1698
		1699	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1700
		1701	When neither C<ca_file> nor C<ca_path> was specified during
		1702	L<AnyEvent::TLS> context creation, and either of these environment
		1703	variables exist, they will be used to specify CA certificate locations
		1704	instead of a system-dependent default.
		1705
		1706	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1707
		1708	When these are set to C<1>, then the respective modules are not
		1709	loaded. Mostly good for testing AnyEvent itself.
		1710
		1711	=back
955		1712
956	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1713	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
957		1714
958	This is an advanced topic that you do not normally need to use AnyEvent in	1715	This is an advanced topic that you do not normally need to use AnyEvent in
959	a module. This section is only of use to event loop authors who want to	1716	a module. This section is only of use to event loop authors who want to
…		…
993		1750
994	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1751	I<rxvt-unicode> also cheats a bit by not providing blocking access to
995	condition variables: code blocking while waiting for a condition will	1752	condition variables: code blocking while waiting for a condition will
996	C<die>. This still works with most modules/usages, and blocking calls must	1753	C<die>. This still works with most modules/usages, and blocking calls must
997	not be done in an interactive application, so it makes sense.	1754	not be done in an interactive application, so it makes sense.
998
999	=head1 ENVIRONMENT VARIABLES
1000
1001	The following environment variables are used by this module:
1002
1003	=over 4
1004
1005	=item C<PERL_ANYEVENT_VERBOSE>
1006
1007	By default, AnyEvent will be completely silent except in fatal
1008	conditions. You can set this environment variable to make AnyEvent more
1009	talkative.
1010
1011	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1012	conditions, such as not being able to load the event model specified by
1013	C<PERL_ANYEVENT_MODEL>.
1014
1015	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1016	model it chooses.
1017
1018	=item C<PERL_ANYEVENT_MODEL>
1019
1020	This can be used to specify the event model to be used by AnyEvent, before
1021	autodetection and -probing kicks in. It must be a string consisting
1022	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1023	and the resulting module name is loaded and if the load was successful,
1024	used as event model. If it fails to load AnyEvent will proceed with
1025	autodetection and -probing.
1026
1027	This functionality might change in future versions.
1028
1029	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1030	could start your program like this:
1031
1032	PERL_ANYEVENT_MODEL=Perl perl ...
1033
1034	=back
1035		1755
1036	=head1 EXAMPLE PROGRAM	1756	=head1 EXAMPLE PROGRAM
1037		1757
1038	The following program uses an I/O watcher to read data from STDIN, a timer	1758	The following program uses an I/O watcher to read data from STDIN, a timer
1039	to display a message once per second, and a condition variable to quit the	1759	to display a message once per second, and a condition variable to quit the
…		…
1048	poll => 'r',	1768	poll => 'r',
1049	cb => sub {	1769	cb => sub {
1050	warn "io event <$_[0]>\n"; # will always output <r>	1770	warn "io event <$_[0]>\n"; # will always output <r>
1051	chomp (my $input = <STDIN>); # read a line	1771	chomp (my $input = <STDIN>); # read a line
1052	warn "read: $input\n"; # output what has been read	1772	warn "read: $input\n"; # output what has been read
1053	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1773	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1054	},	1774	},
1055	);	1775	);
1056		1776
1057	my $time_watcher; # can only be used once	1777	my $time_watcher; # can only be used once
1058		1778
…		…
1063	});	1783	});
1064	}	1784	}
1065		1785
1066	new_timer; # create first timer	1786	new_timer; # create first timer
1067		1787
1068	$cv->wait; # wait until user enters /^q/i	1788	$cv->recv; # wait until user enters /^q/i
1069		1789
1070	=head1 REAL-WORLD EXAMPLE	1790	=head1 REAL-WORLD EXAMPLE
1071		1791
1072	Consider the L<Net::FCP> module. It features (among others) the following	1792	Consider the L<Net::FCP> module. It features (among others) the following
1073	API calls, which are to freenet what HTTP GET requests are to http:	1793	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1123	syswrite $txn->{fh}, $txn->{request}	1843	syswrite $txn->{fh}, $txn->{request}
1124	or die "connection or write error";	1844	or die "connection or write error";
1125	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1845	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1126		1846
1127	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1847	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1128	result and signals any possible waiters that the request ahs finished:	1848	result and signals any possible waiters that the request has finished:
1129		1849
1130	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1850	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1131		1851
1132	if (end-of-file or data complete) {	1852	if (end-of-file or data complete) {
1133	$txn->{result} = $txn->{buf};	1853	$txn->{result} = $txn->{buf};
1134	$txn->{finished}->broadcast;	1854	$txn->{finished}->send;
1135	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1855	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1136	}	1856	}
1137		1857
1138	The C<result> method, finally, just waits for the finished signal (if the	1858	The C<result> method, finally, just waits for the finished signal (if the
1139	request was already finished, it doesn't wait, of course, and returns the	1859	request was already finished, it doesn't wait, of course, and returns the
1140	data:	1860	data:
1141		1861
1142	$txn->{finished}->wait;	1862	$txn->{finished}->recv;
1143	return $txn->{result};	1863	return $txn->{result};
1144		1864
1145	The actual code goes further and collects all errors (C<die>s, exceptions)	1865	The actual code goes further and collects all errors (C<die>s, exceptions)
1146	that occured during request processing. The C<result> method detects	1866	that occurred during request processing. The C<result> method detects
1147	whether an exception as thrown (it is stored inside the $txn object)	1867	whether an exception as thrown (it is stored inside the $txn object)
1148	and just throws the exception, which means connection errors and other	1868	and just throws the exception, which means connection errors and other
1149	problems get reported tot he code that tries to use the result, not in a	1869	problems get reported tot he code that tries to use the result, not in a
1150	random callback.	1870	random callback.
1151		1871
…		…
1182		1902
1183	my $quit = AnyEvent->condvar;	1903	my $quit = AnyEvent->condvar;
1184		1904
1185	$fcp->txn_client_get ($url)->cb (sub {	1905	$fcp->txn_client_get ($url)->cb (sub {
1186	...	1906	...
1187	$quit->broadcast;	1907	$quit->send;
1188	});	1908	});
1189		1909
1190	$quit->wait;	1910	$quit->recv;
1191		1911
1192		1912
1193	=head1 BENCHMARKS	1913	=head1 BENCHMARKS
1194		1914
1195	To give you an idea of the performance and overheads that AnyEvent adds	1915	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1197	of various event loops I prepared some benchmarks.	1917	of various event loops I prepared some benchmarks.
1198		1918
1199	=head2 BENCHMARKING ANYEVENT OVERHEAD	1919	=head2 BENCHMARKING ANYEVENT OVERHEAD
1200		1920
1201	Here is a benchmark of various supported event models used natively and	1921	Here is a benchmark of various supported event models used natively and
1202	through anyevent. The benchmark creates a lot of timers (with a zero	1922	through AnyEvent. The benchmark creates a lot of timers (with a zero
1203	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1923	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1204	which it is), lets them fire exactly once and destroys them again.	1924	which it is), lets them fire exactly once and destroys them again.
1205		1925
1206	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1926	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1207	distribution.	1927	distribution.
…		…
1224	all watchers, to avoid adding memory overhead. That means closure creation	1944	all watchers, to avoid adding memory overhead. That means closure creation
1225	and memory usage is not included in the figures.	1945	and memory usage is not included in the figures.
1226		1946
1227	I<invoke> is the time, in microseconds, used to invoke a simple	1947	I<invoke> is the time, in microseconds, used to invoke a simple
1228	callback. The callback simply counts down a Perl variable and after it was	1948	callback. The callback simply counts down a Perl variable and after it was
1229	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1949	invoked "watcher" times, it would C<< ->send >> a condvar once to
1230	signal the end of this phase.	1950	signal the end of this phase.
1231		1951
1232	I<destroy> is the time, in microseconds, that it takes to destroy a single	1952	I<destroy> is the time, in microseconds, that it takes to destroy a single
1233	watcher.	1953	watcher.
1234		1954
1235	=head3 Results	1955	=head3 Results
1236		1956
1237	name watchers bytes create invoke destroy comment	1957	name watchers bytes create invoke destroy comment
1238	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1958	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1239	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1959	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1240	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1960	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1241	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1961	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1242	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1962	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1243	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1963	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1964	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1965	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1244	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1966	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1245	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1967	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1246	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1968	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1247	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1969	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1248		1970
1249	=head3 Discussion	1971	=head3 Discussion
1250		1972
1251	The benchmark does I<not> measure scalability of the event loop very	1973	The benchmark does I<not> measure scalability of the event loop very
1252	well. For example, a select-based event loop (such as the pure perl one)	1974	well. For example, a select-based event loop (such as the pure perl one)
…		…
1277	performance becomes really bad with lots of file descriptors (and few of	1999	performance becomes really bad with lots of file descriptors (and few of
1278	them active), of course, but this was not subject of this benchmark.	2000	them active), of course, but this was not subject of this benchmark.
1279		2001
1280	The C<Event> module has a relatively high setup and callback invocation	2002	The C<Event> module has a relatively high setup and callback invocation
1281	cost, but overall scores in on the third place.	2003	cost, but overall scores in on the third place.
		2004
		2005	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2006	when using its pure perl backend.
1282		2007
1283	C<Glib>'s memory usage is quite a bit higher, but it features a	2008	C<Glib>'s memory usage is quite a bit higher, but it features a
1284	faster callback invocation and overall ends up in the same class as	2009	faster callback invocation and overall ends up in the same class as
1285	C<Event>. However, Glib scales extremely badly, doubling the number of	2010	C<Event>. However, Glib scales extremely badly, doubling the number of
1286	watchers increases the processing time by more than a factor of four,	2011	watchers increases the processing time by more than a factor of four,
…		…
1330		2055
1331	=back	2056	=back
1332		2057
1333	=head2 BENCHMARKING THE LARGE SERVER CASE	2058	=head2 BENCHMARKING THE LARGE SERVER CASE
1334		2059
1335	This benchmark atcually benchmarks the event loop itself. It works by	2060	This benchmark actually benchmarks the event loop itself. It works by
1336	creating a number of "servers": each server consists of a socketpair, a	2061	creating a number of "servers": each server consists of a socket pair, a
1337	timeout watcher that gets reset on activity (but never fires), and an I/O	2062	timeout watcher that gets reset on activity (but never fires), and an I/O
1338	watcher waiting for input on one side of the socket. Each time the socket	2063	watcher waiting for input on one side of the socket. Each time the socket
1339	watcher reads a byte it will write that byte to a random other "server".	2064	watcher reads a byte it will write that byte to a random other "server".
1340		2065
1341	The effect is that there will be a lot of I/O watchers, only part of which	2066	The effect is that there will be a lot of I/O watchers, only part of which
1342	are active at any one point (so there is a constant number of active	2067	are active at any one point (so there is a constant number of active
1343	fds for each loop iterstaion, but which fds these are is random). The	2068	fds for each loop iteration, but which fds these are is random). The
1344	timeout is reset each time something is read because that reflects how	2069	timeout is reset each time something is read because that reflects how
1345	most timeouts work (and puts extra pressure on the event loops).	2070	most timeouts work (and puts extra pressure on the event loops).
1346		2071
1347	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	2072	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1348	(1%) are active. This mirrors the activity of large servers with many	2073	(1%) are active. This mirrors the activity of large servers with many
1349	connections, most of which are idle at any one point in time.	2074	connections, most of which are idle at any one point in time.
1350		2075
1351	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2076	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1352	distribution.	2077	distribution.
…		…
1354	=head3 Explanation of the columns	2079	=head3 Explanation of the columns
1355		2080
1356	I<sockets> is the number of sockets, and twice the number of "servers" (as	2081	I<sockets> is the number of sockets, and twice the number of "servers" (as
1357	each server has a read and write socket end).	2082	each server has a read and write socket end).
1358		2083
1359	I<create> is the time it takes to create a socketpair (which is	2084	I<create> is the time it takes to create a socket pair (which is
1360	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	2085	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1361		2086
1362	I<request>, the most important value, is the time it takes to handle a	2087	I<request>, the most important value, is the time it takes to handle a
1363	single "request", that is, reading the token from the pipe and forwarding	2088	single "request", that is, reading the token from the pipe and forwarding
1364	it to another server. This includes deleting the old timeout and creating	2089	it to another server. This includes deleting the old timeout and creating
1365	a new one that moves the timeout into the future.	2090	a new one that moves the timeout into the future.
1366		2091
1367	=head3 Results	2092	=head3 Results
1368		2093
1369	name sockets create request	2094	name sockets create request
1370	EV 20000 69.01 11.16	2095	EV 20000 69.01 11.16
1371	Perl 20000 73.32 35.87	2096	Perl 20000 73.32 35.87
		2097	IOAsync 20000 157.00 98.14 epoll
		2098	IOAsync 20000 159.31 616.06 poll
1372	Event 20000 212.62 257.32	2099	Event 20000 212.62 257.32
1373	Glib 20000 651.16 1896.30	2100	Glib 20000 651.16 1896.30
1374	POE 20000 349.67 12317.24 uses POE::Loop::Event	2101	POE 20000 349.67 12317.24 uses POE::Loop::Event
1375		2102
1376	=head3 Discussion	2103	=head3 Discussion
1377		2104
1378	This benchmark I<does> measure scalability and overall performance of the	2105	This benchmark I<does> measure scalability and overall performance of the
1379	particular event loop.	2106	particular event loop.
…		…
1381	EV is again fastest. Since it is using epoll on my system, the setup time	2108	EV is again fastest. Since it is using epoll on my system, the setup time
1382	is relatively high, though.	2109	is relatively high, though.
1383		2110
1384	Perl surprisingly comes second. It is much faster than the C-based event	2111	Perl surprisingly comes second. It is much faster than the C-based event
1385	loops Event and Glib.	2112	loops Event and Glib.
		2113
		2114	IO::Async performs very well when using its epoll backend, and still quite
		2115	good compared to Glib when using its pure perl backend.
1386		2116
1387	Event suffers from high setup time as well (look at its code and you will	2117	Event suffers from high setup time as well (look at its code and you will
1388	understand why). Callback invocation also has a high overhead compared to	2118	understand why). Callback invocation also has a high overhead compared to
1389	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2119	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1390	uses select or poll in basically all documented configurations.	2120	uses select or poll in basically all documented configurations.
…		…
1437	speed most when you have lots of watchers, not when you only have a few of	2167	speed most when you have lots of watchers, not when you only have a few of
1438	them).	2168	them).
1439		2169
1440	EV is again fastest.	2170	EV is again fastest.
1441		2171
1442	Perl again comes second. It is noticably faster than the C-based event	2172	Perl again comes second. It is noticeably faster than the C-based event
1443	loops Event and Glib, although the difference is too small to really	2173	loops Event and Glib, although the difference is too small to really
1444	matter.	2174	matter.
1445		2175
1446	POE also performs much better in this case, but is is still far behind the	2176	POE also performs much better in this case, but is is still far behind the
1447	others.	2177	others.
…		…
1450		2180
1451	=over 4	2181	=over 4
1452		2182
1453	=item * C-based event loops perform very well with small number of	2183	=item * C-based event loops perform very well with small number of
1454	watchers, as the management overhead dominates.	2184	watchers, as the management overhead dominates.
		2185
		2186	=back
		2187
		2188	=head2 THE IO::Lambda BENCHMARK
		2189
		2190	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2191	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2192	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2193	shouldn't come as a surprise to anybody). As such, the benchmark is
		2194	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2195	very optimal. But how would AnyEvent compare when used without the extra
		2196	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2197
		2198	The benchmark itself creates an echo-server, and then, for 500 times,
		2199	connects to the echo server, sends a line, waits for the reply, and then
		2200	creates the next connection. This is a rather bad benchmark, as it doesn't
		2201	test the efficiency of the framework or much non-blocking I/O, but it is a
		2202	benchmark nevertheless.
		2203
		2204	name runtime
		2205	Lambda/select 0.330 sec
		2206	+ optimized 0.122 sec
		2207	Lambda/AnyEvent 0.327 sec
		2208	+ optimized 0.138 sec
		2209	Raw sockets/select 0.077 sec
		2210	POE/select, components 0.662 sec
		2211	POE/select, raw sockets 0.226 sec
		2212	POE/select, optimized 0.404 sec
		2213
		2214	AnyEvent/select/nb 0.085 sec
		2215	AnyEvent/EV/nb 0.068 sec
		2216	+state machine 0.134 sec
		2217
		2218	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2219	benchmarks actually make blocking connects and use 100% blocking I/O,
		2220	defeating the purpose of an event-based solution. All of the newly
		2221	written AnyEvent benchmarks use 100% non-blocking connects (using
		2222	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2223	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2224	generally require a lot more bookkeeping and event handling than blocking
		2225	connects (which involve a single syscall only).
		2226
		2227	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2228	offers similar expressive power as POE and IO::Lambda, using conventional
		2229	Perl syntax. This means that both the echo server and the client are 100%
		2230	non-blocking, further placing it at a disadvantage.
		2231
		2232	As you can see, the AnyEvent + EV combination even beats the
		2233	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2234	backend easily beats IO::Lambda and POE.
		2235
		2236	And even the 100% non-blocking version written using the high-level (and
		2237	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2238	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2239	in a non-blocking way.
		2240
		2241	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2242	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2243	part of the IO::lambda distribution and were used without any changes.
		2244
		2245
		2246	=head1 SIGNALS
		2247
		2248	AnyEvent currently installs handlers for these signals:
		2249
		2250	=over 4
		2251
		2252	=item SIGCHLD
		2253
		2254	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2255	emulation for event loops that do not support them natively. Also, some
		2256	event loops install a similar handler.
		2257
		2258	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2259	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2260
		2261	=item SIGPIPE
		2262
		2263	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2264	when AnyEvent gets loaded.
		2265
		2266	The rationale for this is that AnyEvent users usually do not really depend
		2267	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2268	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2269	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2270	some random socket.
		2271
		2272	The rationale for installing a no-op handler as opposed to ignoring it is
		2273	that this way, the handler will be restored to defaults on exec.
		2274
		2275	Feel free to install your own handler, or reset it to defaults.
		2276
		2277	=back
		2278
		2279	=cut
		2280
		2281	undef $SIG{CHLD}
		2282	if $SIG{CHLD} eq 'IGNORE';
		2283
		2284	$SIG{PIPE} = sub { }
		2285	unless defined $SIG{PIPE};
		2286
		2287	=head1 RECOMMENDED/OPTIONAL MODULES
		2288
		2289	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2290	it's built-in modules) are required to use it.
		2291
		2292	That does not mean that AnyEvent won't take advantage of some additional
		2293	modules if they are installed.
		2294
		2295	This section epxlains which additional modules will be used, and how they
		2296	affect AnyEvent's operetion.
		2297
		2298	=over 4
		2299
		2300	=item L<Async::Interrupt>
		2301
		2302	This slightly arcane module is used to implement fast signal handling: To
		2303	my knowledge, there is no way to do completely race-free and quick
		2304	signal handling in pure perl. To ensure that signals still get
		2305	delivered, AnyEvent will start an interval timer to wake up perl (and
		2306	catch the signals) with some delay (default is 10 seconds, look for
		2307	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2308
		2309	If this module is available, then it will be used to implement signal
		2310	catching, which means that signals will not be delayed, and the event loop
		2311	will not be interrupted regularly, which is more efficient (And good for
		2312	battery life on laptops).
		2313
		2314	This affects not just the pure-perl event loop, but also other event loops
		2315	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2316
		2317	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2318	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2319	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2320	does nothing for those backends.
		2321
		2322	=item L<EV>
		2323
		2324	This module isn't really "optional", as it is simply one of the backend
		2325	event loops that AnyEvent can use. However, it is simply the best event
		2326	loop available in terms of features, speed and stability: It supports
		2327	the AnyEvent API optimally, implements all the watcher types in XS, does
		2328	automatic timer adjustments even when no monotonic clock is available,
		2329	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2330	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2331	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2332
		2333	=item L<Guard>
		2334
		2335	The guard module, when used, will be used to implement
		2336	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2337	lot less memory), but otherwise doesn't affect guard operation much. It is
		2338	purely used for performance.
		2339
		2340	=item L<JSON> and L<JSON::XS>
		2341
		2342	This module is required when you want to read or write JSON data via
		2343	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2344	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2345
		2346	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2347	installed.
		2348
		2349	=item L<Net::SSLeay>
		2350
		2351	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2352	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2353	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2354
		2355	=item L<Time::HiRes>
		2356
		2357	This module is part of perl since release 5.008. It will be used when the
		2358	chosen event library does not come with a timing source on it's own. The
		2359	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2360	try to use a monotonic clock for timing stability.
1455		2361
1456	=back	2362	=back
1457		2363
1458		2364
1459	=head1 FORK	2365	=head1 FORK
…		…
1461	Most event libraries are not fork-safe. The ones who are usually are	2367	Most event libraries are not fork-safe. The ones who are usually are
1462	because they rely on inefficient but fork-safe C<select> or C<poll>	2368	because they rely on inefficient but fork-safe C<select> or C<poll>
1463	calls. Only L<EV> is fully fork-aware.	2369	calls. Only L<EV> is fully fork-aware.
1464		2370
1465	If you have to fork, you must either do so I<before> creating your first	2371	If you have to fork, you must either do so I<before> creating your first
1466	watcher OR you must not use AnyEvent at all in the child.	2372	watcher OR you must not use AnyEvent at all in the child OR you must do
		2373	something completely out of the scope of AnyEvent.
1467		2374
1468		2375
1469	=head1 SECURITY CONSIDERATIONS	2376	=head1 SECURITY CONSIDERATIONS
1470		2377
1471	AnyEvent can be forced to load any event model via	2378	AnyEvent can be forced to load any event model via
…		…
1476	specified in the variable.	2383	specified in the variable.
1477		2384
1478	You can make AnyEvent completely ignore this variable by deleting it	2385	You can make AnyEvent completely ignore this variable by deleting it
1479	before the first watcher gets created, e.g. with a C<BEGIN> block:	2386	before the first watcher gets created, e.g. with a C<BEGIN> block:
1480		2387
1481	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2388	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1482		2389
1483	use AnyEvent;	2390	use AnyEvent;
1484		2391
1485	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2392	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1486	be used to probe what backend is used and gain other information (which is	2393	be used to probe what backend is used and gain other information (which is
1487	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2394	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2395	$ENV{PERL_ANYEVENT_STRICT}.
		2396
		2397	Note that AnyEvent will remove I<all> environment variables starting with
		2398	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2399	enabled.
		2400
		2401
		2402	=head1 BUGS
		2403
		2404	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2405	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2406	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2407	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2408	pronounced).
1488		2409
1489		2410
1490	=head1 SEE ALSO	2411	=head1 SEE ALSO
		2412
		2413	Utility functions: L<AnyEvent::Util>.
1491		2414
1492	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2415	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1493	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2416	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1494		2417
1495	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2418	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1496	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2419	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1497	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2420	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1498	L<AnyEvent::Impl::POE>.	2421	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1499		2422
		2423	Non-blocking file handles, sockets, TCP clients and
		2424	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2425
		2426	Asynchronous DNS: L<AnyEvent::DNS>.
		2427
1500	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2428	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2429	L<Coro::Event>,
1501		2430
1502	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2431	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2432	L<AnyEvent::HTTP>.
1503		2433
1504		2434
1505	=head1 AUTHOR	2435	=head1 AUTHOR
1506		2436
1507	Marc Lehmann <schmorp@schmorp.de>	2437	Marc Lehmann <schmorp@schmorp.de>
1508	http://home.schmorp.de/	2438	http://home.schmorp.de/
1509		2439
1510	=cut	2440	=cut
1511		2441
1512	1	2442	1
1513		2443

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