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1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
22		42
23	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
24		44
25	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
28		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
		58
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		60
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
33		63
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
36		66
37	First and foremost, I<AnyEvent is not an event model> itself, it only	67	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	68	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	69	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	70	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	71	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
43		74
44	The goal of AnyEvent is to offer module authors the ability to do event	75	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	76	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	77	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
48	model you use.	79	model you use.
49		80
50	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	84	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	85	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
56		87
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
60	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
61	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
62	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
63	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
64	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
65		96
66	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
70	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
71	technically possible.	102	technically possible.
72		103
73	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
74	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
80	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
81	model, you should I<not> use this module.	112	model, you should I<not> use this module.
82		113
83	=head1 DESCRIPTION	114	=head1 DESCRIPTION
84		115
85	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
86	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
87	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
88	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
89		120
90	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
91	module.	122	module.
92		123
93	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
94	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
95	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
96	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
97	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
98	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
99	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Loop> should always work, so
100	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
101	found, AnyEvent will fall back to a pure-perl event loop, which is not
102	very efficient, but should work everywhere.
103		132
104	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
105	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
106	that model the default. For example:	135	that model the default. For example:
107		136
…		…
109	use AnyEvent;	138	use AnyEvent;
110		139
111	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
112		141
113	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
114	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
115	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
116		146
117	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
118	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	other event modules you can load it explicitly and enjoy the high
119	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
120		150
121	=head1 WATCHERS	151	=head1 WATCHERS
122		152
123	AnyEvent has the central concept of a I<watcher>, which is an object that	153	AnyEvent has the central concept of a I<watcher>, which is an object that
124	stores relevant data for each kind of event you are waiting for, such as	154	stores relevant data for each kind of event you are waiting for, such as
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
129	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
130	is in control).	160	is in control).
131		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
132	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
133	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	170	to it).
135		171
136	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
137		173
138	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
139	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
140		176
141	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
142		178
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
145	undef $w;	181	undef $w;
146	});	182	});
…		…
149	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
150	declared.	186	declared.
151		187
152	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
153		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
156		198
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
158	for events. C<poll> must be a string that is either C<r> or C<w>,	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
160	respectively. C<cb> is the callback to invoke each time the file handle	209	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		210
163	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
166		214
167	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
168	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
169	underlying file descriptor.	217	underlying file descriptor.
170		218
171	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
173	handles.	221	handles.
174		222
175	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
176	watcher.	224	watcher.
…		…
181	undef $w;	229	undef $w;
182	});	230	});
183		231
184	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
185		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	243	method with the following mandatory arguments:
188		244
189	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		248
193	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
196		252
197	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
198	parameter, C<interval>, as a positive number, then the callback will be	254	parameter, C<interval>, as a strictly positive number (> 0), then the
199	invoked regularly at that interval (in fractional seconds) after the first	255	callback will be invoked regularly at that interval (in fractional
200	invocation.	256	seconds) after the first invocation. If C<interval> is specified with a
		257	false value, then it is treated as if it were not specified at all.
201		258
202	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
203	attempt is done to avoid timer drift in most backends, so the interval is	260	attempt is made to avoid timer drift in most backends, so the interval is
204	only approximate.	261	only approximate.
205		262
206	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
207		264
208	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
226		283
227	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
228	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
229	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
230	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
231	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
232		289
233	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
234	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
235	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
236	timers.	293	timers.
237		294
238	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
239	AnyEvent API.	296	AnyEvent API.
…		…
261	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
262	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
263		320
264	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
265	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
266	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
267		324
268	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
269	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
270		327
271	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
272	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
273		330
274	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
275	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
276	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
277	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
278	after three seconds.	335	after three seconds.
279		336
…		…
297	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
298	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
299	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
300	account.	357	account.
301		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
		362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
		363	above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
302	=back	381	=back
303		382
304	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
305		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
306	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
307	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
308	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
309		390
310	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
311	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
312	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
313		394
…		…
315	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
316	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
317	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
318		399
319	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
320	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
321		403
322	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
323	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
324		407
325	Example: exit on SIGINT	408	Example: exit on SIGINT
326		409
327	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
328		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
329	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
330		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
331	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
332		454
333	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
334	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
335	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
336	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
337	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
338	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
339		469
340	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
341	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
342	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
343		473
344	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
345	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
346	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
347		480
348	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
349	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
350	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which case the latency and race
		488	problems mentioned in the description of signal watchers apply.
351		489
352	Example: fork a process and wait for it	490	Example: fork a process and wait for it
353		491
354	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
355		493
…		…
365	);	503	);
366		504
367	# do something else, then wait for process exit	505	# do something else, then wait for process exit
368	$done->recv;	506	$done->recv;
369		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
		547
370	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
371		554
372	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
373	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
374	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
375		558
376	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
377	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
378		561
379	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
380	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
381		566
382	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
383	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
384	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
385	becomes true.	570	becomes true, with the condition variable as the first argument (but not
		571	the results).
386		572
387	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
388	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
389	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
390	->send >> method).	576	->send >> method).
391		577
392	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
393	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
394	in time where multiple outstanding events have been processed. And yet	580
395	another way to call them is transactions - each condition variable can be	581	=over 4
396	used to represent a transaction, which finishes at some point and delivers	582
397	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
398		601
399	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
400	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
401	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
402	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
415		618
416	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
417	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
418	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
419	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
420	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
421		624
422	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
423	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
424	for the send to occur.	627	for the send to occur.
425		628
426	Example: wait for a timer.	629	Example: wait for a timer.
427		630
428	# wait till the result is ready	631	# condition: "wait till the timer is fired"
429	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
430		633
431	# do something such as adding a timer	634	# create the timer - we could wait for, say
432	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
433	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
434	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
435	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
436	after => 1,	639	after => 1,
437	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
438	);	641	);
439		642
440	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
441	# calls send	644	# calls ->send
442	$result_ready->recv;	645	$timer_fired->recv;
443		646
444	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
445	condition variables are also code references.	648	variables are also callable directly.
446		649
447	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
448	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
449	$done->recv;	652	$done->recv;
		653
		654	Example: Imagine an API that returns a condvar and doesn't support
		655	callbacks. This is how you make a synchronous call, for example from
		656	the main program:
		657
		658	use AnyEvent::CouchDB;
		659
		660	...
		661
		662	my @info = $couchdb->info->recv;
		663
		664	And this is how you would just set a callback to be called whenever the
		665	results are available:
		666
		667	$couchdb->info->cb (sub {
		668	my @info = $_[0]->recv;
		669	});
450		670
451	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
452		672
453	These methods should only be used by the producing side, i.e. the	673	These methods should only be used by the producing side, i.e. the
454	code/module that eventually sends the signal. Note that it is also	674	code/module that eventually sends the signal. Note that it is also
…		…
467	immediately from within send.	687	immediately from within send.
468		688
469	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
470	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
471		691
472	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
473	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
474	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
475	overloading, so as tempting as it may be, passing a condition variable
476	instead of a callback does not work. Both the pure perl and EV loops
477	support overloading, however, as well as all functions that use perl to
478	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
479	example).
480		695
481	=item $cv->croak ($error)	696	=item $cv->croak ($error)
482		697
483	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
484	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
485		700
486	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
487	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
488		707
489	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
490		709
491	=item $cv->end	710	=item $cv->end
492
493	These two methods are EXPERIMENTAL and MIGHT CHANGE.
494		711
495	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
496	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
497	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
498		715
499	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
500	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
501	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
502	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
503	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
504		722
505	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
506		730
507	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
508		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
509	my %result;	757	my %result;
510	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
511		759
512	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
513	$cv->begin;	761	$cv->begin;
514	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
515	$result{$host} = ...;	763	$result{$host} = ...;
…		…
530	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
531	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
532	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
533	doesn't execute once).	781	doesn't execute once).
534		782
535	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
536	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
537	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
538	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
539		788
540	=back	789	=back
541		790
542	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
543		792
…		…
547	=over 4	796	=over 4
548		797
549	=item $cv->recv	798	=item $cv->recv
550		799
551	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
552	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
553	normally.	802	normally.
554		803
555	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
556	will return immediately.	805	will return immediately.
557		806
…		…
559	function will call C<croak>.	808	function will call C<croak>.
560		809
561	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
562	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
563		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
564	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
565	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
566	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
567	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
568	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
569	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
570	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
571		827
572	Another reason I<never> to C<< ->recv >> in a module is that you cannot
573	sensibly have two C<< ->recv >>'s in parallel, as that would require
574	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
575	can supply.
576
577	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
578	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
579	versions and also integrates coroutines into AnyEvent, making blocking
580	C<< ->recv >> calls perfectly safe as long as they are done from another
581	coroutine (one that doesn't run the event loop).
582
583	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
584	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
585	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
586	waits otherwise.	831	waits otherwise.
587		832
588	=item $bool = $cv->ready	833	=item $bool = $cv->ready
589		834
590	Returns true when the condition is "true", i.e. whether C<send> or	835	Returns true when the condition is "true", i.e. whether C<send> or
591	C<croak> have been called.	836	C<croak> have been called.
592		837
593	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
594		839
595	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
596	replaces it before doing so.	841	replaces it before doing so.
597		842
598	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
599	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
600	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
601	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
602		848
603	=back	849	=back
604		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
605	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
606		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
607	=over 4	919	=over 4
608		920
609	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
610		922
611	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
612	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
613	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
614	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
615	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
616		930	will be C<urxvt::anyevent>).
617	The known classes so far are:
618
619	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
620	AnyEvent::Impl::Event based on Event, second best choice.
621	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
622	AnyEvent::Impl::Glib based on Glib, third-best choice.
623	AnyEvent::Impl::Tk based on Tk, very bad choice.
624	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
625	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
626	AnyEvent::Impl::POE based on POE, not generic enough for full support.
627
628	There is no support for WxWidgets, as WxWidgets has no support for
629	watching file handles. However, you can use WxWidgets through the
630	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
631	second, which was considered to be too horrible to even consider for
632	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
633	it's adaptor.
634
635	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
636	autodetecting them.
637		931
638	=item AnyEvent::detect	932	=item AnyEvent::detect
639		933
640	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
641	if necessary. You should only call this function right before you would	935	if necessary. You should only call this function right before you would
642	have created an AnyEvent watcher anyway, that is, as late as possible at	936	have created an AnyEvent watcher anyway, that is, as late as possible at
643	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
644		945
645	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
646		947
647	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
648	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
649		961
650	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
651	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
652	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
653		982
654	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
655		984
656	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
657	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
658	the event loop has been chosen.	987	after the event loop has been chosen.
659		988
660	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
661	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
662	and the array will be ignored.	991	array will be ignored.
663		992
664	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
665		1053
666	=back	1054	=back
667		1055
668	=head1 WHAT TO DO IN A MODULE	1056	=head1 WHAT TO DO IN A MODULE
669		1057
…		…
680	because it will stall the whole program, and the whole point of using	1068	because it will stall the whole program, and the whole point of using
681	events is to stay interactive.	1069	events is to stay interactive.
682		1070
683	It is fine, however, to call C<< ->recv >> when the user of your module	1071	It is fine, however, to call C<< ->recv >> when the user of your module
684	requests it (i.e. if you create a http request object ad have a method	1072	requests it (i.e. if you create a http request object ad have a method
685	called C<results> that returns the results, it should call C<< ->recv >>	1073	called C<results> that returns the results, it may call C<< ->recv >>
686	freely, as the user of your module knows what she is doing. always).	1074	freely, as the user of your module knows what she is doing. Always).
687		1075
688	=head1 WHAT TO DO IN THE MAIN PROGRAM	1076	=head1 WHAT TO DO IN THE MAIN PROGRAM
689		1077
690	There will always be a single main program - the only place that should	1078	There will always be a single main program - the only place that should
691	dictate which event model to use.	1079	dictate which event model to use.
692		1080
693	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1081	If the program is not event-based, it need not do anything special, even
694	do anything special (it does not need to be event-based) and let AnyEvent	1082	when it depends on a module that uses an AnyEvent. If the program itself
695	decide which implementation to chose if some module relies on it.	1083	uses AnyEvent, but does not care which event loop is used, all it needs
		1084	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1085	available loop implementation.
696		1086
697	If the main program relies on a specific event model - for example, in	1087	If the main program relies on a specific event model - for example, in
698	Gtk2 programs you have to rely on the Glib module - you should load the	1088	Gtk2 programs you have to rely on the Glib module - you should load the
699	event module before loading AnyEvent or any module that uses it: generally	1089	event module before loading AnyEvent or any module that uses it: generally
700	speaking, you should load it as early as possible. The reason is that	1090	speaking, you should load it as early as possible. The reason is that
701	modules might create watchers when they are loaded, and AnyEvent will	1091	modules might create watchers when they are loaded, and AnyEvent will
702	decide on the event model to use as soon as it creates watchers, and it	1092	decide on the event model to use as soon as it creates watchers, and it
703	might chose the wrong one unless you load the correct one yourself.	1093	might choose the wrong one unless you load the correct one yourself.
704		1094
705	You can chose to use a pure-perl implementation by loading the	1095	You can chose to use a pure-perl implementation by loading the
706	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1096	C<AnyEvent::Loop> module, which gives you similar behaviour
707	everywhere, but letting AnyEvent chose the model is generally better.	1097	everywhere, but letting AnyEvent chose the model is generally better.
708		1098
709	=head2 MAINLOOP EMULATION	1099	=head2 MAINLOOP EMULATION
710		1100
711	Sometimes (often for short test scripts, or even standalone programs who	1101	Sometimes (often for short test scripts, or even standalone programs who
…		…
724		1114
725		1115
726	=head1 OTHER MODULES	1116	=head1 OTHER MODULES
727		1117
728	The following is a non-exhaustive list of additional modules that use	1118	The following is a non-exhaustive list of additional modules that use
729	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1119	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
730	in the same program. Some of the modules come with AnyEvent, some are	1120	modules and other event loops in the same program. Some of the modules
731	available via CPAN.	1121	come as part of AnyEvent, the others are available via CPAN.
732		1122
733	=over 4	1123	=over 4
734		1124
735	=item L<AnyEvent::Util>	1125	=item L<AnyEvent::Util>
736		1126
737	Contains various utility functions that replace often-used but blocking	1127	Contains various utility functions that replace often-used blocking
738	functions such as C<inet_aton> by event-/callback-based versions.	1128	functions such as C<inet_aton> with event/callback-based versions.
739		1129
740	=item L<AnyEvent::Socket>	1130	=item L<AnyEvent::Socket>
741		1131
742	Provides various utility functions for (internet protocol) sockets,	1132	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	1133	addresses and name resolution. Also functions to create non-blocking tcp
…		…
745		1135
746	=item L<AnyEvent::Handle>	1136	=item L<AnyEvent::Handle>
747		1137
748	Provide read and write buffers, manages watchers for reads and writes,	1138	Provide read and write buffers, manages watchers for reads and writes,
749	supports raw and formatted I/O, I/O queued and fully transparent and	1139	supports raw and formatted I/O, I/O queued and fully transparent and
750	non-blocking SSL/TLS.	1140	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
751		1141
752	=item L<AnyEvent::DNS>	1142	=item L<AnyEvent::DNS>
753		1143
754	Provides rich asynchronous DNS resolver capabilities.	1144	Provides rich asynchronous DNS resolver capabilities.
755		1145
		1146	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1147
		1148	Implement event-based interfaces to the protocols of the same name (for
		1149	the curious, IGS is the International Go Server and FCP is the Freenet
		1150	Client Protocol).
		1151
		1152	=item L<AnyEvent::Handle::UDP>
		1153
		1154	Here be danger!
		1155
		1156	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1157	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1158	its use of a stream-based API with a protocol that isn't streamable, that
		1159	the only way to improve it is to delete it.
		1160
		1161	It features data corruption (but typically only under load) and general
		1162	confusion. On top, the author is not only clueless about UDP but also
		1163	fact-resistant - some gems of his understanding: "connect doesn't work
		1164	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1165	packets", "I don't need to implement proper error checking as UDP doesn't
		1166	support error checking" and so on - he doesn't even understand what's
		1167	wrong with his module when it is explained to him.
		1168
756	=item L<AnyEvent::HTTP>	1169	=item L<AnyEvent::DBI>
757		1170
758	A simple-to-use HTTP library that is capable of making a lot of concurrent	1171	Executes L<DBI> requests asynchronously in a proxy process for you,
759	HTTP requests.	1172	notifying you in an event-based way when the operation is finished.
		1173
		1174	=item L<AnyEvent::AIO>
		1175
		1176	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1177	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1178	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1179	file I/O, and much more.
760		1180
761	=item L<AnyEvent::HTTPD>	1181	=item L<AnyEvent::HTTPD>
762		1182
763	Provides a simple web application server framework.	1183	A simple embedded webserver.
764		1184
765	=item L<AnyEvent::FastPing>	1185	=item L<AnyEvent::FastPing>
766		1186
767	The fastest ping in the west.	1187	The fastest ping in the west.
768		1188
769	=item L<AnyEvent::DBI>
770
771	Executes L<DBI> requests asynchronously in a proxy process.
772
773	=item L<AnyEvent::AIO>
774
775	Truly asynchronous I/O, should be in the toolbox of every event
776	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
777	together.
778
779	=item L<AnyEvent::BDB>
780
781	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
782	L<BDB> and AnyEvent together.
783
784	=item L<AnyEvent::GPSD>
785
786	A non-blocking interface to gpsd, a daemon delivering GPS information.
787
788	=item L<AnyEvent::IGS>
789
790	A non-blocking interface to the Internet Go Server protocol (used by
791	L<App::IGS>).
792
793	=item L<Net::IRC3>
794
795	AnyEvent based IRC client module family.
796
797	=item L<Net::XMPP2>
798
799	AnyEvent based XMPP (Jabber protocol) module family.
800
801	=item L<Net::FCP>
802
803	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
804	of AnyEvent.
805
806	=item L<Event::ExecFlow>
807
808	High level API for event-based execution flow control.
809
810	=item L<Coro>	1189	=item L<Coro>
811		1190
812	Has special support for AnyEvent via L<Coro::AnyEvent>.	1191	Has special support for AnyEvent via L<Coro::AnyEvent>.
813		1192
814	=item L<IO::Lambda>
815
816	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
817
818	=back	1193	=back
819		1194
820	=cut	1195	=cut
821		1196
822	package AnyEvent;	1197	package AnyEvent;
823		1198
824	no warnings;	1199	# basically a tuned-down version of common::sense
825	use strict;	1200	sub common_sense {
		1201	# from common:.sense 3.4
		1202	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1203	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1204	$^H |= 0x00000600;
		1205	}
826		1206
		1207	BEGIN { AnyEvent::common_sense }
		1208
827	use Carp;	1209	use Carp ();
828		1210
829	our $VERSION = 4.2;	1211	our $VERSION = '6.01';
830	our $MODEL;	1212	our $MODEL;
831		1213
832	our $AUTOLOAD;
833	our @ISA;	1214	our @ISA;
834		1215
835	our @REGISTRY;	1216	our @REGISTRY;
836		1217
837	our $WIN32;	1218	our $VERBOSE;
838		1219
839	BEGIN {	1220	BEGIN {
840	my $win32 = ! ! ($^O =~ /mswin32/i);	1221	require "AnyEvent/constants.pl";
841	eval "sub WIN32(){ $win32 }";
842	}
843		1222
		1223	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1224
		1225	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1226	if ${^TAINT};
		1227
844	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1228	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1229
		1230	}
		1231
		1232	our $MAX_SIGNAL_LATENCY = 10;
845		1233
846	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1234	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
847		1235
848	{	1236	{
849	my $idx;	1237	my $idx;
850	$PROTOCOL{$_} = ++$idx	1238	$PROTOCOL{$_} = ++$idx
851	for reverse split /\s*,\s*/,	1239	for reverse split /\s*,\s*/,
852	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1240	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
853	}	1241	}
854		1242
		1243	our @post_detect;
		1244
		1245	sub post_detect(&) {
		1246	my ($cb) = @_;
		1247
		1248	push @post_detect, $cb;
		1249
		1250	defined wantarray
		1251	? bless \$cb, "AnyEvent::Util::postdetect"
		1252	: ()
		1253	}
		1254
		1255	sub AnyEvent::Util::postdetect::DESTROY {
		1256	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1257	}
		1258
		1259	our $POSTPONE_W;
		1260	our @POSTPONE;
		1261
		1262	sub _postpone_exec {
		1263	undef $POSTPONE_W;
		1264
		1265	&{ shift @POSTPONE }
		1266	while @POSTPONE;
		1267	}
		1268
		1269	sub postpone(&) {
		1270	push @POSTPONE, shift;
		1271
		1272	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1273
		1274	()
		1275	}
		1276
855	my @models = (	1277	our @models = (
856	[EV:: => AnyEvent::Impl::EV::],	1278	[EV:: => AnyEvent::Impl::EV:: , 1],
857	[Event:: => AnyEvent::Impl::Event::],	1279	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
858	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
859	# everything below here will not be autoprobed	1280	# everything below here will not (normally) be autoprobed
860	# as the pureperl backend should work everywhere	1281	# as the pure perl backend should work everywhere
861	# and is usually faster	1282	# and is usually faster
		1283	[Event:: => AnyEvent::Impl::Event::, 1],
		1284	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1285	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1286	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
862	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1287	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
863	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
864	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
865	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1288	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
866	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1289	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
867	[Wx:: => AnyEvent::Impl::POE::],	1290	[Wx:: => AnyEvent::Impl::POE::],
868	[Prima:: => AnyEvent::Impl::POE::],	1291	[Prima:: => AnyEvent::Impl::POE::],
		1292	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1293	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1294	[FLTK:: => AnyEvent::Impl::FLTK2::],
869	);	1295	);
870		1296
871	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1297	our @isa_hook;
872		1298
873	our @post_detect;	1299	sub _isa_set {
		1300	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
874		1301
		1302	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1303	for 1 .. $#pkg;
		1304
		1305	grep $_ && $_->[1], @isa_hook
		1306	and AE::_reset ();
		1307	}
		1308
		1309	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1310	sub _isa_hook($$;$) {
		1311	my ($i, $pkg, $reset_ae) = @_;
		1312
		1313	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1314
		1315	_isa_set;
		1316	}
		1317
		1318	# all autoloaded methods reserve the complete glob, not just the method slot.
		1319	# due to bugs in perls method cache implementation.
		1320	our @methods = qw(io timer time now now_update signal child idle condvar);
		1321
875	sub post_detect(&) {	1322	sub detect() {
876	my ($cb) = @_;	1323	local $!; # for good measure
		1324	local $SIG{__DIE__}; # we use eval
877		1325
878	if ($MODEL) {	1326	# free some memory
879	$cb->();	1327	*detect = sub () { $MODEL };
		1328	# undef &func doesn't correctly update the method cache. grmbl.
		1329	# so we delete the whole glob. grmbl.
		1330	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1331	# a glob with an active sub. hrm. i hope it works, but perl is
		1332	# usually buggy in this department. sigh.
		1333	delete @{"AnyEvent::"}{@methods};
		1334	undef @methods;
880		1335
881	1	1336	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1337	my $model = $1;
		1338	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1339	if (eval "require $model") {
		1340	$MODEL = $model;
		1341	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
882	} else {	1342	} else {
883	push @post_detect, $cb;	1343	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
884		1344	}
885	defined wantarray
886	? bless \$cb, "AnyEvent::Util::PostDetect"
887	: ()
888	}	1345	}
889	}
890		1346
891	sub AnyEvent::Util::PostDetect::DESTROY {	1347	# check for already loaded models
892	@post_detect = grep $_ != ${$_[0]}, @post_detect;
893	}
894
895	sub detect() {
896	unless ($MODEL) {	1348	unless ($MODEL) {
897	no strict 'refs';	1349	for (@REGISTRY, @models) {
898	local $SIG{__DIE__};	1350	my ($package, $model) = @$_;
899		1351	if (${"$package\::VERSION"} > 0) {
900	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
901	my $model = "AnyEvent::Impl::$1";
902	if (eval "require $model") {	1352	if (eval "require $model") {
903	$MODEL = $model;	1353	$MODEL = $model;
904	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1354	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
905	} else {	1355	last;
906	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1356	}
907	}	1357	}
908	}	1358	}
909		1359
910	# check for already loaded models
911	unless ($MODEL) {	1360	unless ($MODEL) {
		1361	# try to autoload a model
912	for (@REGISTRY, @models) {	1362	for (@REGISTRY, @models) {
913	my ($package, $model) = @$_;	1363	my ($package, $model, $autoload) = @$_;
		1364	if (
		1365	$autoload
		1366	and eval "require $package"
914	if (${"$package\::VERSION"} > 0) {	1367	and ${"$package\::VERSION"} > 0
915	if (eval "require $model") {	1368	and eval "require $model"
		1369	) {
916	$MODEL = $model;	1370	$MODEL = $model;
917	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1371	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
918	last;	1372	last;
919	}
920	}	1373	}
921	}	1374	}
922		1375
923	unless ($MODEL) {	1376	$MODEL
924	# try to load a model	1377	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
		1378	}
		1379	}
925		1380
926	for (@REGISTRY, @models) {	1381	# free memory only needed for probing
927	my ($package, $model) = @$_;	1382	undef @models;
928	if (eval "require $package"	1383	undef @REGISTRY;
929	and ${"$package\::VERSION"} > 0	1384
930	and eval "require $model") {	1385	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
931	$MODEL = $model;	1386
932	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1387	# now nuke some methods that are overridden by the backend.
		1388	# SUPER usage is not allowed in these.
		1389	for (qw(time signal child idle)) {
		1390	undef &{"AnyEvent::Base::$_"}
		1391	if defined &{"$MODEL\::$_"};
		1392	}
		1393
		1394	_isa_set;
		1395
		1396	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1397	require AnyEvent::Strict;
		1398	}
		1399
		1400	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1401	require AnyEvent::Debug;
		1402	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1403	}
		1404
		1405	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1406	require AnyEvent::Socket;
		1407	require AnyEvent::Debug;
		1408
		1409	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1410	$shell =~ s/\$\$/$$/g;
		1411
		1412	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1413	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1414	}
		1415
		1416	(shift @post_detect)->() while @post_detect;
		1417	undef @post_detect;
		1418
		1419	*post_detect = sub(&) {
		1420	shift->();
		1421
		1422	undef
		1423	};
		1424
		1425	$MODEL
		1426	}
		1427
		1428	for my $name (@methods) {
		1429	*$name = sub {
		1430	detect;
		1431	# we use goto because
		1432	# a) it makes the thunk more transparent
		1433	# b) it allows us to delete the thunk later
		1434	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1435	};
		1436	}
		1437
		1438	# utility function to dup a filehandle. this is used by many backends
		1439	# to support binding more than one watcher per filehandle (they usually
		1440	# allow only one watcher per fd, so we dup it to get a different one).
		1441	sub _dupfh($$;$$) {
		1442	my ($poll, $fh, $r, $w) = @_;
		1443
		1444	# cygwin requires the fh mode to be matching, unix doesn't
		1445	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1446
		1447	open my $fh2, $mode, $fh
		1448	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1449
		1450	# we assume CLOEXEC is already set by perl in all important cases
		1451
		1452	($fh2, $rw)
		1453	}
		1454
		1455	=head1 SIMPLIFIED AE API
		1456
		1457	Starting with version 5.0, AnyEvent officially supports a second, much
		1458	simpler, API that is designed to reduce the calling, typing and memory
		1459	overhead by using function call syntax and a fixed number of parameters.
		1460
		1461	See the L<AE> manpage for details.
		1462
		1463	=cut
		1464
		1465	package AE;
		1466
		1467	our $VERSION = $AnyEvent::VERSION;
		1468
		1469	sub _reset() {
		1470	eval q{
		1471	# fall back to the main API by default - backends and AnyEvent::Base
		1472	# implementations can overwrite these.
		1473
		1474	sub io($$$) {
		1475	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1476	}
		1477
		1478	sub timer($$$) {
		1479	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1480	}
		1481
		1482	sub signal($$) {
		1483	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1484	}
		1485
		1486	sub child($$) {
		1487	AnyEvent->child (pid => $_[0], cb => $_[1])
		1488	}
		1489
		1490	sub idle($) {
		1491	AnyEvent->idle (cb => $_[0]);
		1492	}
		1493
		1494	sub cv(;&) {
		1495	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1496	}
		1497
		1498	sub now() {
		1499	AnyEvent->now
		1500	}
		1501
		1502	sub now_update() {
		1503	AnyEvent->now_update
		1504	}
		1505
		1506	sub time() {
		1507	AnyEvent->time
		1508	}
		1509
		1510	*postpone = \&AnyEvent::postpone;
		1511	};
		1512	die if $@;
		1513	}
		1514
		1515	BEGIN { _reset }
		1516
		1517	package AnyEvent::Base;
		1518
		1519	# default implementations for many methods
		1520
		1521	sub time {
		1522	eval q{ # poor man's autoloading {}
		1523	# probe for availability of Time::HiRes
		1524	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1525	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1526	*time = sub { Time::HiRes::time () };
		1527	*AE::time = \& Time::HiRes::time ;
		1528	# if (eval "use POSIX (); (POSIX::times())...
		1529	} else {
		1530	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1531	*time = sub { CORE::time };
		1532	*AE::time = sub (){ CORE::time };
		1533	}
		1534
		1535	*now = \&time;
		1536	};
		1537	die if $@;
		1538
		1539	&time
		1540	}
		1541
		1542	*now = \&time;
		1543	sub now_update { }
		1544
		1545	sub _poll {
		1546	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1547	}
		1548
		1549	# default implementation for ->condvar
		1550	# in fact, the default should not be overwritten
		1551
		1552	sub condvar {
		1553	eval q{ # poor man's autoloading {}
		1554	*condvar = sub {
		1555	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1556	};
		1557
		1558	*AE::cv = sub (;&) {
		1559	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1560	};
		1561	};
		1562	die if $@;
		1563
		1564	&condvar
		1565	}
		1566
		1567	# default implementation for ->signal
		1568
		1569	our $HAVE_ASYNC_INTERRUPT;
		1570
		1571	sub _have_async_interrupt() {
		1572	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1573	&& eval "use Async::Interrupt 1.02 (); 1")
		1574	unless defined $HAVE_ASYNC_INTERRUPT;
		1575
		1576	$HAVE_ASYNC_INTERRUPT
		1577	}
		1578
		1579	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1580	our (%SIG_ASY, %SIG_ASY_W);
		1581	our ($SIG_COUNT, $SIG_TW);
		1582
		1583	# install a dummy wakeup watcher to reduce signal catching latency
		1584	# used by Impls
		1585	sub _sig_add() {
		1586	unless ($SIG_COUNT++) {
		1587	# try to align timer on a full-second boundary, if possible
		1588	my $NOW = AE::now;
		1589
		1590	$SIG_TW = AE::timer
		1591	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1592	$MAX_SIGNAL_LATENCY,
		1593	sub { } # just for the PERL_ASYNC_CHECK
		1594	;
		1595	}
		1596	}
		1597
		1598	sub _sig_del {
		1599	undef $SIG_TW
		1600	unless --$SIG_COUNT;
		1601	}
		1602
		1603	our $_sig_name_init; $_sig_name_init = sub {
		1604	eval q{ # poor man's autoloading {}
		1605	undef $_sig_name_init;
		1606
		1607	if (_have_async_interrupt) {
		1608	*sig2num = \&Async::Interrupt::sig2num;
		1609	*sig2name = \&Async::Interrupt::sig2name;
		1610	} else {
		1611	require Config;
		1612
		1613	my %signame2num;
		1614	@signame2num{ split ' ', $Config::Config{sig_name} }
		1615	= split ' ', $Config::Config{sig_num};
		1616
		1617	my @signum2name;
		1618	@signum2name[values %signame2num] = keys %signame2num;
		1619
		1620	*sig2num = sub($) {
		1621	$_[0] > 0 ? shift : $signame2num{+shift}
		1622	};
		1623	*sig2name = sub ($) {
		1624	$_[0] > 0 ? $signum2name[+shift] : shift
		1625	};
		1626	}
		1627	};
		1628	die if $@;
		1629	};
		1630
		1631	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1632	sub sig2name($) { &$_sig_name_init; &sig2name }
		1633
		1634	sub signal {
		1635	eval q{ # poor man's autoloading {}
		1636	# probe for availability of Async::Interrupt
		1637	if (_have_async_interrupt) {
		1638	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1639
		1640	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1641	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1642
		1643	} else {
		1644	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1645
		1646	if (AnyEvent::WIN32) {
		1647	require AnyEvent::Util;
		1648
		1649	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1650	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1651	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1652	} else {
		1653	pipe $SIGPIPE_R, $SIGPIPE_W;
		1654	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1655	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1656
		1657	# not strictly required, as $^F is normally 2, but let's make sure...
		1658	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1659	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1660	}
		1661
		1662	$SIGPIPE_R
		1663	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1664
		1665	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1666	}
		1667
		1668	*signal = $HAVE_ASYNC_INTERRUPT
		1669	? sub {
		1670	my (undef, %arg) = @_;
		1671
		1672	# async::interrupt
		1673	my $signal = sig2num $arg{signal};
		1674	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1675
		1676	$SIG_ASY{$signal} ||= new Async::Interrupt
		1677	cb => sub { undef $SIG_EV{$signal} },
		1678	signal => $signal,
		1679	pipe => [$SIGPIPE_R->filenos],
		1680	pipe_autodrain => 0,
		1681	;
		1682
		1683	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1684	}
		1685	: sub {
		1686	my (undef, %arg) = @_;
		1687
		1688	# pure perl
		1689	my $signal = sig2name $arg{signal};
		1690	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1691
		1692	$SIG{$signal} ||= sub {
933	last;	1693	local $!;
		1694	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1695	undef $SIG_EV{$signal};
934	}	1696	};
		1697
		1698	# can't do signal processing without introducing races in pure perl,
		1699	# so limit the signal latency.
		1700	_sig_add;
		1701
		1702	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1703	}
		1704	;
		1705
		1706	*AnyEvent::Base::signal::DESTROY = sub {
		1707	my ($signal, $cb) = @{$_[0]};
		1708
		1709	_sig_del;
		1710
		1711	delete $SIG_CB{$signal}{$cb};
		1712
		1713	$HAVE_ASYNC_INTERRUPT
		1714	? delete $SIG_ASY{$signal}
		1715	: # delete doesn't work with older perls - they then
		1716	# print weird messages, or just unconditionally exit
		1717	# instead of getting the default action.
		1718	undef $SIG{$signal}
		1719	unless keys %{ $SIG_CB{$signal} };
		1720	};
		1721
		1722	*_signal_exec = sub {
		1723	$HAVE_ASYNC_INTERRUPT
		1724	? $SIGPIPE_R->drain
		1725	: sysread $SIGPIPE_R, (my $dummy), 9;
		1726
		1727	while (%SIG_EV) {
		1728	for (keys %SIG_EV) {
		1729	delete $SIG_EV{$_};
		1730	&$_ for values %{ $SIG_CB{$_} || {} };
935	}	1731	}
936
937	$MODEL
938	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
939	}	1732	}
940	}	1733	};
941
942	unshift @ISA, $MODEL;
943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
944
945	(shift @post_detect)->() while @post_detect;
946	}
947
948	$MODEL
949	}
950
951	sub AUTOLOAD {
952	(my $func = $AUTOLOAD) =~ s/.*://;
953
954	$method{$func}
955	or croak "$func: not a valid method for AnyEvent objects";
956
957	detect unless $MODEL;
958
959	my $class = shift;
960	$class->$func (@_);
961	}
962
963	package AnyEvent::Base;
964
965	# default implementation for now and time
966
967	use Time::HiRes ();
968
969	sub time { Time::HiRes::time }
970	sub now { Time::HiRes::time }
971
972	# default implementation for ->condvar
973
974	sub condvar {
975	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
976	}
977
978	# default implementation for ->signal
979
980	our %SIG_CB;
981
982	sub signal {
983	my (undef, %arg) = @_;
984
985	my $signal = uc $arg{signal}
986	or Carp::croak "required option 'signal' is missing";
987
988	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
989	$SIG{$signal} ||= sub {
990	$_->() for values %{ $SIG_CB{$signal} || {} };
991	};	1734	};
		1735	die if $@;
992		1736
993	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1737	&signal
994	}
995
996	sub AnyEvent::Base::Signal::DESTROY {
997	my ($signal, $cb) = @{$_[0]};
998
999	delete $SIG_CB{$signal}{$cb};
1000
1001	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1002	}	1738	}
1003		1739
1004	# default implementation for ->child	1740	# default implementation for ->child
1005		1741
1006	our %PID_CB;	1742	our %PID_CB;
1007	our $CHLD_W;	1743	our $CHLD_W;
1008	our $CHLD_DELAY_W;	1744	our $CHLD_DELAY_W;
1009	our $PID_IDLE;
1010	our $WNOHANG;
1011		1745
1012	sub _child_wait {	1746	# used by many Impl's
1013	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1747	sub _emit_childstatus($$) {
		1748	my (undef, $rpid, $rstatus) = @_;
		1749
		1750	$_->($rpid, $rstatus)
1014	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1751	for values %{ $PID_CB{$rpid} || {} },
1015	(values %{ $PID_CB{0} || {} });	1752	values %{ $PID_CB{0} || {} };
1016	}
1017
1018	undef $PID_IDLE;
1019	}
1020
1021	sub _sigchld {
1022	# make sure we deliver these changes "synchronous" with the event loop.
1023	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1024	undef $CHLD_DELAY_W;
1025	&_child_wait;
1026	});
1027	}	1753	}
1028		1754
1029	sub child {	1755	sub child {
		1756	eval q{ # poor man's autoloading {}
		1757	*_sigchld = sub {
		1758	my $pid;
		1759
		1760	AnyEvent->_emit_childstatus ($pid, $?)
		1761	while ($pid = waitpid -1, WNOHANG) > 0;
		1762	};
		1763
		1764	*child = sub {
1030	my (undef, %arg) = @_;	1765	my (undef, %arg) = @_;
1031		1766
1032	defined (my $pid = $arg{pid} + 0)	1767	my $pid = $arg{pid};
1033	or Carp::croak "required option 'pid' is missing";	1768	my $cb = $arg{cb};
1034		1769
1035	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1770	$PID_CB{$pid}{$cb+0} = $cb;
1036		1771
1037	unless ($WNOHANG) {
1038	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1039	}
1040
1041	unless ($CHLD_W) {	1772	unless ($CHLD_W) {
1042	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1773	$CHLD_W = AE::signal CHLD => \&_sigchld;
1043	# child could be a zombie already, so make at least one round	1774	# child could be a zombie already, so make at least one round
1044	&_sigchld;	1775	&_sigchld;
1045	}	1776	}
1046		1777
1047	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1778	bless [$pid, $cb+0], "AnyEvent::Base::child"
1048	}	1779	};
1049		1780
1050	sub AnyEvent::Base::Child::DESTROY {	1781	*AnyEvent::Base::child::DESTROY = sub {
1051	my ($pid, $cb) = @{$_[0]};	1782	my ($pid, $icb) = @{$_[0]};
1052		1783
1053	delete $PID_CB{$pid}{$cb};	1784	delete $PID_CB{$pid}{$icb};
1054	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1785	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1055		1786
1056	undef $CHLD_W unless keys %PID_CB;	1787	undef $CHLD_W unless keys %PID_CB;
		1788	};
		1789	};
		1790	die if $@;
		1791
		1792	&child
		1793	}
		1794
		1795	# idle emulation is done by simply using a timer, regardless
		1796	# of whether the process is idle or not, and not letting
		1797	# the callback use more than 50% of the time.
		1798	sub idle {
		1799	eval q{ # poor man's autoloading {}
		1800	*idle = sub {
		1801	my (undef, %arg) = @_;
		1802
		1803	my ($cb, $w, $rcb) = $arg{cb};
		1804
		1805	$rcb = sub {
		1806	if ($cb) {
		1807	$w = AE::time;
		1808	&$cb;
		1809	$w = AE::time - $w;
		1810
		1811	# never use more then 50% of the time for the idle watcher,
		1812	# within some limits
		1813	$w = 0.0001 if $w < 0.0001;
		1814	$w = 5 if $w > 5;
		1815
		1816	$w = AE::timer $w, 0, $rcb;
		1817	} else {
		1818	# clean up...
		1819	undef $w;
		1820	undef $rcb;
		1821	}
		1822	};
		1823
		1824	$w = AE::timer 0.05, 0, $rcb;
		1825
		1826	bless \\$cb, "AnyEvent::Base::idle"
		1827	};
		1828
		1829	*AnyEvent::Base::idle::DESTROY = sub {
		1830	undef $${$_[0]};
		1831	};
		1832	};
		1833	die if $@;
		1834
		1835	&idle
1057	}	1836	}
1058		1837
1059	package AnyEvent::CondVar;	1838	package AnyEvent::CondVar;
1060		1839
1061	our @ISA = AnyEvent::CondVar::Base::;	1840	our @ISA = AnyEvent::CondVar::Base::;
1062		1841
		1842	# only to be used for subclassing
		1843	sub new {
		1844	my $class = shift;
		1845	bless AnyEvent->condvar (@_), $class
		1846	}
		1847
1063	package AnyEvent::CondVar::Base;	1848	package AnyEvent::CondVar::Base;
1064		1849
1065	use overload	1850	#use overload
1066	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1851	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1067	fallback => 1;	1852	# fallback => 1;
		1853
		1854	# save 300+ kilobytes by dirtily hardcoding overloading
		1855	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1856	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1857	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1858	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1859
		1860	our $WAITING;
1068		1861
1069	sub _send {	1862	sub _send {
1070	# nop	1863	# nop
		1864	}
		1865
		1866	sub _wait {
		1867	AnyEvent->_poll until $_[0]{_ae_sent};
1071	}	1868	}
1072		1869
1073	sub send {	1870	sub send {
1074	my $cv = shift;	1871	my $cv = shift;
1075	$cv->{_ae_sent} = [@_];	1872	$cv->{_ae_sent} = [@_];
…		…
1084		1881
1085	sub ready {	1882	sub ready {
1086	$_[0]{_ae_sent}	1883	$_[0]{_ae_sent}
1087	}	1884	}
1088		1885
1089	sub _wait {
1090	AnyEvent->one_event while !$_[0]{_ae_sent};
1091	}
1092
1093	sub recv {	1886	sub recv {
		1887	unless ($_[0]{_ae_sent}) {
		1888	$WAITING
		1889	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1890
		1891	local $WAITING = 1;
1094	$_[0]->_wait;	1892	$_[0]->_wait;
		1893	}
1095		1894
1096	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1895	$_[0]{_ae_croak}
1097	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1896	and Carp::croak $_[0]{_ae_croak};
		1897
		1898	wantarray
		1899	? @{ $_[0]{_ae_sent} }
		1900	: $_[0]{_ae_sent}[0]
1098	}	1901	}
1099		1902
1100	sub cb {	1903	sub cb {
1101	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1904	my $cv = shift;
		1905
		1906	@_
		1907	and $cv->{_ae_cb} = shift
		1908	and $cv->{_ae_sent}
		1909	and (delete $cv->{_ae_cb})->($cv);
		1910
1102	$_[0]{_ae_cb}	1911	$cv->{_ae_cb}
1103	}	1912	}
1104		1913
1105	sub begin {	1914	sub begin {
1106	++$_[0]{_ae_counter};	1915	++$_[0]{_ae_counter};
1107	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1916	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1112	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1921	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1113	}	1922	}
1114		1923
1115	# undocumented/compatibility with pre-3.4	1924	# undocumented/compatibility with pre-3.4
1116	*broadcast = \&send;	1925	*broadcast = \&send;
1117	*wait = \&_wait;	1926	*wait = \&recv;
		1927
		1928	=head1 ERROR AND EXCEPTION HANDLING
		1929
		1930	In general, AnyEvent does not do any error handling - it relies on the
		1931	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1932	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1933	checking of all AnyEvent methods, however, which is highly useful during
		1934	development.
		1935
		1936	As for exception handling (i.e. runtime errors and exceptions thrown while
		1937	executing a callback), this is not only highly event-loop specific, but
		1938	also not in any way wrapped by this module, as this is the job of the main
		1939	program.
		1940
		1941	The pure perl event loop simply re-throws the exception (usually
		1942	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1943	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1944	so on.
		1945
		1946	=head1 ENVIRONMENT VARIABLES
		1947
		1948	The following environment variables are used by this module or its
		1949	submodules.
		1950
		1951	Note that AnyEvent will remove I<all> environment variables starting with
		1952	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1953	enabled.
		1954
		1955	=over 4
		1956
		1957	=item C<PERL_ANYEVENT_VERBOSE>
		1958
		1959	By default, AnyEvent will be completely silent except in fatal
		1960	conditions. You can set this environment variable to make AnyEvent more
		1961	talkative.
		1962
		1963	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1964	conditions, such as not being able to load the event model specified by
		1965	C<PERL_ANYEVENT_MODEL>.
		1966
		1967	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1968	model it chooses.
		1969
		1970	When set to C<8> or higher, then AnyEvent will report extra information on
		1971	which optional modules it loads and how it implements certain features.
		1972
		1973	=item C<PERL_ANYEVENT_STRICT>
		1974
		1975	AnyEvent does not do much argument checking by default, as thorough
		1976	argument checking is very costly. Setting this variable to a true value
		1977	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1978	check the arguments passed to most method calls. If it finds any problems,
		1979	it will croak.
		1980
		1981	In other words, enables "strict" mode.
		1982
		1983	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		1984	>>, it is definitely recommended to keep it off in production. Keeping
		1985	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1986	can be very useful, however.
		1987
		1988	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1989
		1990	If this env variable is set, then its contents will be interpreted by
		1991	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		1992	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		1993	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		1994
		1995	This takes place when the first watcher is created.
		1996
		1997	For example, to bind a debug shell on a unix domain socket in
		1998	F<< /tmp/debug<pid>.sock >>, you could use this:
		1999
		2000	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug\$\$.sock perlprog
		2001
		2002	Note that creating sockets in F</tmp> is very unsafe on multiuser
		2003	systems.
		2004
		2005	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2006
		2007	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2008	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2009
		2010	=item C<PERL_ANYEVENT_MODEL>
		2011
		2012	This can be used to specify the event model to be used by AnyEvent, before
		2013	auto detection and -probing kicks in.
		2014
		2015	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2016	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2017	resulting module name is loaded and - if the load was successful - used as
		2018	event model backend. If it fails to load then AnyEvent will proceed with
		2019	auto detection and -probing.
		2020
		2021	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2022	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2023	the end of a string designates a module name and quotes it appropriately).
		2024
		2025	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2026	could start your program like this:
		2027
		2028	PERL_ANYEVENT_MODEL=Perl perl ...
		2029
		2030	=item C<PERL_ANYEVENT_PROTOCOLS>
		2031
		2032	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2033	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2034	of auto probing).
		2035
		2036	Must be set to a comma-separated list of protocols or address families,
		2037	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2038	used, and preference will be given to protocols mentioned earlier in the
		2039	list.
		2040
		2041	This variable can effectively be used for denial-of-service attacks
		2042	against local programs (e.g. when setuid), although the impact is likely
		2043	small, as the program has to handle conenction and other failures anyways.
		2044
		2045	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2046	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2047	- only support IPv4, never try to resolve or contact IPv6
		2048	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2049	IPv6, but prefer IPv6 over IPv4.
		2050
		2051	=item C<PERL_ANYEVENT_EDNS0>
		2052
		2053	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		2054	for DNS. This extension is generally useful to reduce DNS traffic, but
		2055	some (broken) firewalls drop such DNS packets, which is why it is off by
		2056	default.
		2057
		2058	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2059	EDNS0 in its DNS requests.
		2060
		2061	=item C<PERL_ANYEVENT_MAX_FORKS>
		2062
		2063	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2064	will create in parallel.
		2065
		2066	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2067
		2068	The default value for the C<max_outstanding> parameter for the default DNS
		2069	resolver - this is the maximum number of parallel DNS requests that are
		2070	sent to the DNS server.
		2071
		2072	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2073
		2074	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2075	configuration) in the default resolver. When set to the empty string, no
		2076	default config will be used.
		2077
		2078	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2079
		2080	When neither C<ca_file> nor C<ca_path> was specified during
		2081	L<AnyEvent::TLS> context creation, and either of these environment
		2082	variables exist, they will be used to specify CA certificate locations
		2083	instead of a system-dependent default.
		2084
		2085	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2086
		2087	When these are set to C<1>, then the respective modules are not
		2088	loaded. Mostly good for testing AnyEvent itself.
		2089
		2090	=back
1118		2091
1119	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2092	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1120		2093
1121	This is an advanced topic that you do not normally need to use AnyEvent in	2094	This is an advanced topic that you do not normally need to use AnyEvent in
1122	a module. This section is only of use to event loop authors who want to	2095	a module. This section is only of use to event loop authors who want to
…		…
1156		2129
1157	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2130	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1158	condition variables: code blocking while waiting for a condition will	2131	condition variables: code blocking while waiting for a condition will
1159	C<die>. This still works with most modules/usages, and blocking calls must	2132	C<die>. This still works with most modules/usages, and blocking calls must
1160	not be done in an interactive application, so it makes sense.	2133	not be done in an interactive application, so it makes sense.
1161
1162	=head1 ENVIRONMENT VARIABLES
1163
1164	The following environment variables are used by this module:
1165
1166	=over 4
1167
1168	=item C<PERL_ANYEVENT_VERBOSE>
1169
1170	By default, AnyEvent will be completely silent except in fatal
1171	conditions. You can set this environment variable to make AnyEvent more
1172	talkative.
1173
1174	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1175	conditions, such as not being able to load the event model specified by
1176	C<PERL_ANYEVENT_MODEL>.
1177
1178	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1179	model it chooses.
1180
1181	=item C<PERL_ANYEVENT_MODEL>
1182
1183	This can be used to specify the event model to be used by AnyEvent, before
1184	auto detection and -probing kicks in. It must be a string consisting
1185	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1186	and the resulting module name is loaded and if the load was successful,
1187	used as event model. If it fails to load AnyEvent will proceed with
1188	auto detection and -probing.
1189
1190	This functionality might change in future versions.
1191
1192	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1193	could start your program like this:
1194
1195	PERL_ANYEVENT_MODEL=Perl perl ...
1196
1197	=item C<PERL_ANYEVENT_PROTOCOLS>
1198
1199	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1200	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1201	of auto probing).
1202
1203	Must be set to a comma-separated list of protocols or address families,
1204	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1205	used, and preference will be given to protocols mentioned earlier in the
1206	list.
1207
1208	This variable can effectively be used for denial-of-service attacks
1209	against local programs (e.g. when setuid), although the impact is likely
1210	small, as the program has to handle connection errors already-
1211
1212	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1213	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1214	- only support IPv4, never try to resolve or contact IPv6
1215	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1216	IPv6, but prefer IPv6 over IPv4.
1217
1218	=item C<PERL_ANYEVENT_EDNS0>
1219
1220	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1221	for DNS. This extension is generally useful to reduce DNS traffic, but
1222	some (broken) firewalls drop such DNS packets, which is why it is off by
1223	default.
1224
1225	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1226	EDNS0 in its DNS requests.
1227
1228	=item C<PERL_ANYEVENT_MAX_FORKS>
1229
1230	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1231	will create in parallel.
1232
1233	=back
1234		2134
1235	=head1 EXAMPLE PROGRAM	2135	=head1 EXAMPLE PROGRAM
1236		2136
1237	The following program uses an I/O watcher to read data from STDIN, a timer	2137	The following program uses an I/O watcher to read data from STDIN, a timer
1238	to display a message once per second, and a condition variable to quit the	2138	to display a message once per second, and a condition variable to quit the
…		…
1251	warn "read: $input\n"; # output what has been read	2151	warn "read: $input\n"; # output what has been read
1252	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2152	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1253	},	2153	},
1254	);	2154	);
1255		2155
1256	my $time_watcher; # can only be used once
1257
1258	sub new_timer {
1259	$timer = AnyEvent->timer (after => 1, cb => sub {	2156	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1260	warn "timeout\n"; # print 'timeout' about every second	2157	warn "timeout\n"; # print 'timeout' at most every second
1261	&new_timer; # and restart the time
1262	});	2158	});
1263	}
1264
1265	new_timer; # create first timer
1266		2159
1267	$cv->recv; # wait until user enters /^q/i	2160	$cv->recv; # wait until user enters /^q/i
1268		2161
1269	=head1 REAL-WORLD EXAMPLE	2162	=head1 REAL-WORLD EXAMPLE
1270		2163
…		…
1343		2236
1344	The actual code goes further and collects all errors (C<die>s, exceptions)	2237	The actual code goes further and collects all errors (C<die>s, exceptions)
1345	that occurred during request processing. The C<result> method detects	2238	that occurred during request processing. The C<result> method detects
1346	whether an exception as thrown (it is stored inside the $txn object)	2239	whether an exception as thrown (it is stored inside the $txn object)
1347	and just throws the exception, which means connection errors and other	2240	and just throws the exception, which means connection errors and other
1348	problems get reported tot he code that tries to use the result, not in a	2241	problems get reported to the code that tries to use the result, not in a
1349	random callback.	2242	random callback.
1350		2243
1351	All of this enables the following usage styles:	2244	All of this enables the following usage styles:
1352		2245
1353	1. Blocking:	2246	1. Blocking:
…		…
1401	through AnyEvent. The benchmark creates a lot of timers (with a zero	2294	through AnyEvent. The benchmark creates a lot of timers (with a zero
1402	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2295	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1403	which it is), lets them fire exactly once and destroys them again.	2296	which it is), lets them fire exactly once and destroys them again.
1404		2297
1405	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2298	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1406	distribution.	2299	distribution. It uses the L<AE> interface, which makes a real difference
		2300	for the EV and Perl backends only.
1407		2301
1408	=head3 Explanation of the columns	2302	=head3 Explanation of the columns
1409		2303
1410	I<watcher> is the number of event watchers created/destroyed. Since	2304	I<watcher> is the number of event watchers created/destroyed. Since
1411	different event models feature vastly different performances, each event	2305	different event models feature vastly different performances, each event
…		…
1432	watcher.	2326	watcher.
1433		2327
1434	=head3 Results	2328	=head3 Results
1435		2329
1436	name watchers bytes create invoke destroy comment	2330	name watchers bytes create invoke destroy comment
1437	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2331	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1438	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2332	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1439	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2333	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1440	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2334	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1441	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2335	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1442	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2336	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2337	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2338	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1443	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2339	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1444	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2340	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1445	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2341	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1446	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2342	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1447		2343
1448	=head3 Discussion	2344	=head3 Discussion
1449		2345
1450	The benchmark does I<not> measure scalability of the event loop very	2346	The benchmark does I<not> measure scalability of the event loop very
1451	well. For example, a select-based event loop (such as the pure perl one)	2347	well. For example, a select-based event loop (such as the pure perl one)
…		…
1463	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2359	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1464	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2360	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1465	cycles with POE.	2361	cycles with POE.
1466		2362
1467	C<EV> is the sole leader regarding speed and memory use, which are both	2363	C<EV> is the sole leader regarding speed and memory use, which are both
1468	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2364	maximal/minimal, respectively. When using the L<AE> API there is zero
		2365	overhead (when going through the AnyEvent API create is about 5-6 times
		2366	slower, with other times being equal, so still uses far less memory than
1469	far less memory than any other event loop and is still faster than Event	2367	any other event loop and is still faster than Event natively).
1470	natively.
1471		2368
1472	The pure perl implementation is hit in a few sweet spots (both the	2369	The pure perl implementation is hit in a few sweet spots (both the
1473	constant timeout and the use of a single fd hit optimisations in the perl	2370	constant timeout and the use of a single fd hit optimisations in the perl
1474	interpreter and the backend itself). Nevertheless this shows that it	2371	interpreter and the backend itself). Nevertheless this shows that it
1475	adds very little overhead in itself. Like any select-based backend its	2372	adds very little overhead in itself. Like any select-based backend its
1476	performance becomes really bad with lots of file descriptors (and few of	2373	performance becomes really bad with lots of file descriptors (and few of
1477	them active), of course, but this was not subject of this benchmark.	2374	them active), of course, but this was not subject of this benchmark.
1478		2375
1479	The C<Event> module has a relatively high setup and callback invocation	2376	The C<Event> module has a relatively high setup and callback invocation
1480	cost, but overall scores in on the third place.	2377	cost, but overall scores in on the third place.
		2378
		2379	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2380	when using its pure perl backend.
1481		2381
1482	C<Glib>'s memory usage is quite a bit higher, but it features a	2382	C<Glib>'s memory usage is quite a bit higher, but it features a
1483	faster callback invocation and overall ends up in the same class as	2383	faster callback invocation and overall ends up in the same class as
1484	C<Event>. However, Glib scales extremely badly, doubling the number of	2384	C<Event>. However, Glib scales extremely badly, doubling the number of
1485	watchers increases the processing time by more than a factor of four,	2385	watchers increases the processing time by more than a factor of four,
…		…
1520	(even when used without AnyEvent), but most event loops have acceptable	2420	(even when used without AnyEvent), but most event loops have acceptable
1521	performance with or without AnyEvent.	2421	performance with or without AnyEvent.
1522		2422
1523	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2423	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1524	the actual event loop, only with extremely fast event loops such as EV	2424	the actual event loop, only with extremely fast event loops such as EV
1525	adds AnyEvent significant overhead.	2425	does AnyEvent add significant overhead.
1526		2426
1527	=item * You should avoid POE like the plague if you want performance or	2427	=item * You should avoid POE like the plague if you want performance or
1528	reasonable memory usage.	2428	reasonable memory usage.
1529		2429
1530	=back	2430	=back
…		…
1546	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2446	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1547	(1%) are active. This mirrors the activity of large servers with many	2447	(1%) are active. This mirrors the activity of large servers with many
1548	connections, most of which are idle at any one point in time.	2448	connections, most of which are idle at any one point in time.
1549		2449
1550	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2450	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1551	distribution.	2451	distribution. It uses the L<AE> interface, which makes a real difference
		2452	for the EV and Perl backends only.
1552		2453
1553	=head3 Explanation of the columns	2454	=head3 Explanation of the columns
1554		2455
1555	I<sockets> is the number of sockets, and twice the number of "servers" (as	2456	I<sockets> is the number of sockets, and twice the number of "servers" (as
1556	each server has a read and write socket end).	2457	each server has a read and write socket end).
…		…
1563	it to another server. This includes deleting the old timeout and creating	2464	it to another server. This includes deleting the old timeout and creating
1564	a new one that moves the timeout into the future.	2465	a new one that moves the timeout into the future.
1565		2466
1566	=head3 Results	2467	=head3 Results
1567		2468
1568	name sockets create request	2469	name sockets create request
1569	EV 20000 69.01 11.16	2470	EV 20000 62.66 7.99
1570	Perl 20000 73.32 35.87	2471	Perl 20000 68.32 32.64
1571	Event 20000 212.62 257.32	2472	IOAsync 20000 174.06 101.15 epoll
1572	Glib 20000 651.16 1896.30	2473	IOAsync 20000 174.67 610.84 poll
		2474	Event 20000 202.69 242.91
		2475	Glib 20000 557.01 1689.52
1573	POE 20000 349.67 12317.24 uses POE::Loop::Event	2476	POE 20000 341.54 12086.32 uses POE::Loop::Event
1574		2477
1575	=head3 Discussion	2478	=head3 Discussion
1576		2479
1577	This benchmark I<does> measure scalability and overall performance of the	2480	This benchmark I<does> measure scalability and overall performance of the
1578	particular event loop.	2481	particular event loop.
…		…
1580	EV is again fastest. Since it is using epoll on my system, the setup time	2483	EV is again fastest. Since it is using epoll on my system, the setup time
1581	is relatively high, though.	2484	is relatively high, though.
1582		2485
1583	Perl surprisingly comes second. It is much faster than the C-based event	2486	Perl surprisingly comes second. It is much faster than the C-based event
1584	loops Event and Glib.	2487	loops Event and Glib.
		2488
		2489	IO::Async performs very well when using its epoll backend, and still quite
		2490	good compared to Glib when using its pure perl backend.
1585		2491
1586	Event suffers from high setup time as well (look at its code and you will	2492	Event suffers from high setup time as well (look at its code and you will
1587	understand why). Callback invocation also has a high overhead compared to	2493	understand why). Callback invocation also has a high overhead compared to
1588	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2494	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1589	uses select or poll in basically all documented configurations.	2495	uses select or poll in basically all documented configurations.
…		…
1652	=item * C-based event loops perform very well with small number of	2558	=item * C-based event loops perform very well with small number of
1653	watchers, as the management overhead dominates.	2559	watchers, as the management overhead dominates.
1654		2560
1655	=back	2561	=back
1656		2562
		2563	=head2 THE IO::Lambda BENCHMARK
		2564
		2565	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2566	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2567	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2568	shouldn't come as a surprise to anybody). As such, the benchmark is
		2569	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2570	very optimal. But how would AnyEvent compare when used without the extra
		2571	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2572
		2573	The benchmark itself creates an echo-server, and then, for 500 times,
		2574	connects to the echo server, sends a line, waits for the reply, and then
		2575	creates the next connection. This is a rather bad benchmark, as it doesn't
		2576	test the efficiency of the framework or much non-blocking I/O, but it is a
		2577	benchmark nevertheless.
		2578
		2579	name runtime
		2580	Lambda/select 0.330 sec
		2581	+ optimized 0.122 sec
		2582	Lambda/AnyEvent 0.327 sec
		2583	+ optimized 0.138 sec
		2584	Raw sockets/select 0.077 sec
		2585	POE/select, components 0.662 sec
		2586	POE/select, raw sockets 0.226 sec
		2587	POE/select, optimized 0.404 sec
		2588
		2589	AnyEvent/select/nb 0.085 sec
		2590	AnyEvent/EV/nb 0.068 sec
		2591	+state machine 0.134 sec
		2592
		2593	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2594	benchmarks actually make blocking connects and use 100% blocking I/O,
		2595	defeating the purpose of an event-based solution. All of the newly
		2596	written AnyEvent benchmarks use 100% non-blocking connects (using
		2597	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2598	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2599	generally require a lot more bookkeeping and event handling than blocking
		2600	connects (which involve a single syscall only).
		2601
		2602	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2603	offers similar expressive power as POE and IO::Lambda, using conventional
		2604	Perl syntax. This means that both the echo server and the client are 100%
		2605	non-blocking, further placing it at a disadvantage.
		2606
		2607	As you can see, the AnyEvent + EV combination even beats the
		2608	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2609	backend easily beats IO::Lambda and POE.
		2610
		2611	And even the 100% non-blocking version written using the high-level (and
		2612	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2613	higher level ("unoptimised") abstractions by a large margin, even though
		2614	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2615
		2616	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2617	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2618	part of the IO::Lambda distribution and were used without any changes.
		2619
		2620
		2621	=head1 SIGNALS
		2622
		2623	AnyEvent currently installs handlers for these signals:
		2624
		2625	=over 4
		2626
		2627	=item SIGCHLD
		2628
		2629	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2630	emulation for event loops that do not support them natively. Also, some
		2631	event loops install a similar handler.
		2632
		2633	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2634	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2635
		2636	=item SIGPIPE
		2637
		2638	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2639	when AnyEvent gets loaded.
		2640
		2641	The rationale for this is that AnyEvent users usually do not really depend
		2642	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2643	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2644	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2645	some random socket.
		2646
		2647	The rationale for installing a no-op handler as opposed to ignoring it is
		2648	that this way, the handler will be restored to defaults on exec.
		2649
		2650	Feel free to install your own handler, or reset it to defaults.
		2651
		2652	=back
		2653
		2654	=cut
		2655
		2656	undef $SIG{CHLD}
		2657	if $SIG{CHLD} eq 'IGNORE';
		2658
		2659	$SIG{PIPE} = sub { }
		2660	unless defined $SIG{PIPE};
		2661
		2662	=head1 RECOMMENDED/OPTIONAL MODULES
		2663
		2664	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2665	its built-in modules) are required to use it.
		2666
		2667	That does not mean that AnyEvent won't take advantage of some additional
		2668	modules if they are installed.
		2669
		2670	This section explains which additional modules will be used, and how they
		2671	affect AnyEvent's operation.
		2672
		2673	=over 4
		2674
		2675	=item L<Async::Interrupt>
		2676
		2677	This slightly arcane module is used to implement fast signal handling: To
		2678	my knowledge, there is no way to do completely race-free and quick
		2679	signal handling in pure perl. To ensure that signals still get
		2680	delivered, AnyEvent will start an interval timer to wake up perl (and
		2681	catch the signals) with some delay (default is 10 seconds, look for
		2682	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2683
		2684	If this module is available, then it will be used to implement signal
		2685	catching, which means that signals will not be delayed, and the event loop
		2686	will not be interrupted regularly, which is more efficient (and good for
		2687	battery life on laptops).
		2688
		2689	This affects not just the pure-perl event loop, but also other event loops
		2690	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2691
		2692	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2693	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2694	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2695	does nothing for those backends.
		2696
		2697	=item L<EV>
		2698
		2699	This module isn't really "optional", as it is simply one of the backend
		2700	event loops that AnyEvent can use. However, it is simply the best event
		2701	loop available in terms of features, speed and stability: It supports
		2702	the AnyEvent API optimally, implements all the watcher types in XS, does
		2703	automatic timer adjustments even when no monotonic clock is available,
		2704	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2705	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2706	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2707
		2708	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2709	then this module will do nothing for you.
		2710
		2711	=item L<Guard>
		2712
		2713	The guard module, when used, will be used to implement
		2714	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2715	lot less memory), but otherwise doesn't affect guard operation much. It is
		2716	purely used for performance.
		2717
		2718	=item L<JSON> and L<JSON::XS>
		2719
		2720	One of these modules is required when you want to read or write JSON data
		2721	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2722	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2723
		2724	=item L<Net::SSLeay>
		2725
		2726	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2727	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2728	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2729
		2730	=item L<Time::HiRes>
		2731
		2732	This module is part of perl since release 5.008. It will be used when the
		2733	chosen event library does not come with a timing source of its own. The
		2734	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2735	try to use a monotonic clock for timing stability.
		2736
		2737	=back
		2738
1657		2739
1658	=head1 FORK	2740	=head1 FORK
1659		2741
1660	Most event libraries are not fork-safe. The ones who are usually are	2742	Most event libraries are not fork-safe. The ones who are usually are
1661	because they rely on inefficient but fork-safe C<select> or C<poll>	2743	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1662	calls. Only L<EV> is fully fork-aware.	2744	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2745	are usually badly thought-out hacks that are incompatible with fork in
		2746	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2747	continue event-processing in both parent and child (or both, if you know
		2748	what you are doing).
		2749
		2750	This means that, in general, you cannot fork and do event processing in
		2751	the child if the event library was initialised before the fork (which
		2752	usually happens when the first AnyEvent watcher is created, or the library
		2753	is loaded).
1663		2754
1664	If you have to fork, you must either do so I<before> creating your first	2755	If you have to fork, you must either do so I<before> creating your first
1665	watcher OR you must not use AnyEvent at all in the child.	2756	watcher OR you must not use AnyEvent at all in the child OR you must do
		2757	something completely out of the scope of AnyEvent.
		2758
		2759	The problem of doing event processing in the parent I<and> the child
		2760	is much more complicated: even for backends that I<are> fork-aware or
		2761	fork-safe, their behaviour is not usually what you want: fork clones all
		2762	watchers, that means all timers, I/O watchers etc. are active in both
		2763	parent and child, which is almost never what you want. USing C<exec>
		2764	to start worker children from some kind of manage rprocess is usually
		2765	preferred, because it is much easier and cleaner, at the expense of having
		2766	to have another binary.
1666		2767
1667		2768
1668	=head1 SECURITY CONSIDERATIONS	2769	=head1 SECURITY CONSIDERATIONS
1669		2770
1670	AnyEvent can be forced to load any event model via	2771	AnyEvent can be forced to load any event model via
…		…
1681		2782
1682	use AnyEvent;	2783	use AnyEvent;
1683		2784
1684	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2785	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1685	be used to probe what backend is used and gain other information (which is	2786	be used to probe what backend is used and gain other information (which is
1686	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2787	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2788	$ENV{PERL_ANYEVENT_STRICT}.
		2789
		2790	Note that AnyEvent will remove I<all> environment variables starting with
		2791	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2792	enabled.
1687		2793
1688		2794
1689	=head1 BUGS	2795	=head1 BUGS
1690		2796
1691	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2797	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1692	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2798	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1693	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2799	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1694	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2800	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1695	pronounced).	2801	pronounced).
1696		2802
1697		2803
1698	=head1 SEE ALSO	2804	=head1 SEE ALSO
1699		2805
		2806	Tutorial/Introduction: L<AnyEvent::Intro>.
		2807
		2808	FAQ: L<AnyEvent::FAQ>.
		2809
1700	Utility functions: L<AnyEvent::Util>.	2810	Utility functions: L<AnyEvent::Util>.
1701		2811
1702	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2812	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
1703	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2813	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1704		2814
1705	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2815	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1706	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2816	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1707	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2817	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1708	L<AnyEvent::Impl::POE>.	2818	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1709		2819
1710	Non-blocking file handles, sockets, TCP clients and	2820	Non-blocking file handles, sockets, TCP clients and
1711	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2821	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1712		2822
1713	Asynchronous DNS: L<AnyEvent::DNS>.	2823	Asynchronous DNS: L<AnyEvent::DNS>.
1714		2824
1715	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2825	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1716		2826
1717	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2827	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2828	L<AnyEvent::HTTP>.
1718		2829
1719		2830
1720	=head1 AUTHOR	2831	=head1 AUTHOR
1721		2832
1722	Marc Lehmann <schmorp@schmorp.de>	2833	Marc Lehmann <schmorp@schmorp.de>

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