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Revision 1.367 by root, Wed Aug 17 02:14:17 2011 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the 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 { ... });
12		17
		18	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
15		21
16	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		24
		25	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		27
		28	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	29	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	30	my ($pid, $status) = @_;
23	...	31	...
24	});	32	});
		33
		34	# called when event loop idle (if applicable)
		35	my $w = AnyEvent->idle (cb => sub { ... });
25		36
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	40	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
33		44
34	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
35	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
36	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
		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.
37		58
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		60
40	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
41	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
57	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
58	model you use.	79	model you use.
59		80
60	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
61	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
62	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
63	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
64	that isn't them. What's worse, all the potential users of your	85	that isn't them. What's worse, all the potential users of your
65	module are 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.
66		87
67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
68	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
69	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
70	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
71	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
72	event models it supports (including stuff like IO::Async, as long as those	93	supports (including stuff like IO::Async, as long as those use one of the
73	use one of the supported event loops. It is trivial to add new event loops	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
74	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
75		96
76	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
77	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
78	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
79	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
80	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
81	technically possible.	102	technically possible.
82		103
83	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
84	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
90	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
91	model, you should I<not> use this module.	112	model, you should I<not> use this module.
92		113
93	=head1 DESCRIPTION	114	=head1 DESCRIPTION
94		115
95	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
96	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
97	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
98	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
99		120
100	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>
101	module.	122	module.
102		123
103	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
104	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
105	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
106	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
107	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
108	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
109	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
110	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
111	found, AnyEvent will fall back to a pure-perl event loop, which is not
112	very efficient, but should work everywhere.
113		132
114	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
115	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
116	that model the default. For example:	135	that model the default. For example:
117		136
…		…
119	use AnyEvent;	138	use AnyEvent;
120		139
121	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
122		141
123	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
124	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,
125	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
126		146
127	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
128	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
129	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
130		150
131	=head1 WATCHERS	151	=head1 WATCHERS
132		152
133	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
134	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
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
138	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
139	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
140	is in control).	160	is in control).
141		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
142	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
143	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
144	to it).	170	to it).
145		171
146	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.
147		173
148	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
149	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.
150		176
151	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
152		178
153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
154	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
155	undef $w;	181	undef $w;
156	});	182	});
…		…
159	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
160	declared.	186	declared.
161		187
162	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
163		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
164	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
165	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
166		198
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
168	(AnyEvent might or might not keep a reference to this file handle). C<poll>	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
169	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
171	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
172		210
173	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
176		214
177	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.
178	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
179	underlying file descriptor.	217	underlying file descriptor.
180		218
181	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
182	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
183	handles.	221	handles.
184		222
185	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
186	watcher.	224	watcher.
…		…
191	undef $w;	229	undef $w;
192	});	230	});
193		231
194	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
195		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
196	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 >>
197	method with the following mandatory arguments:	243	method with the following mandatory arguments:
198		244
199	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
200	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
…		…
202		248
203	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
204	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
205	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
206		252
207	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
208	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
209	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
210	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
211	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
212		258
213	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
214	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
215	only approximate.	261	only approximate.
216		262
217	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
218		264
219	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
237		283
238	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
239	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
240	"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
241	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
242	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.
243		289
244	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
245	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
246	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)
247	timers.	293	timers.
248		294
249	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	296	AnyEvent API.
…		…
272	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
273	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
274		320
275	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
276	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
277	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
278		324
279	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
280	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
281		327
282	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>
283	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
284		330
285	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
286	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
287	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
288	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
289	after three seconds.	335	after three seconds.
290		336
…		…
308	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
309	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
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	357	account.
312		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
313	=back	381	=back
314		382
315	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
316		386
317	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
318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
319	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
320		390
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
327	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,
328	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
329		399
330	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
331	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
332		403
333	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
335		407
336	Example: exit on SIGINT	408	Example: exit on SIGINT
337		409
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$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
340	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
341		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
342	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.
343		454
344	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,
345	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
346	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
347	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
348	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
349	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).
350		469
351	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
352	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
353	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
354		473
355	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
356	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
357	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.
358		480
359	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
360	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
361	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.
362		489
363	Example: fork a process and wait for it	490	Example: fork a process and wait for it
364		491
365	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
366		493
…		…
376	);	503	);
377		504
378	# do something else, then wait for process exit	505	# do something else, then wait for process exit
379	$done->recv;	506	$done->recv;
380		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
381	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
382		554
383	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
384	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
385	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
386		558
387	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
388	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).
389		561
390	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
391	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.
392		566
393	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
394
395	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
396
397	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
398	becomes true, with the condition variable as the first argument (but not	570	becomes true, with the condition variable as the first argument (but not
399	the results).	571	the results).
400		572
401	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
402	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
403	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<<
404	->send >> method).	576	->send >> method).
405		577
406	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
407	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:
408	in time where multiple outstanding events have been processed. And yet	580
409	another way to call them is transactions - each condition variable can be	581	=over 4
410	used to represent a transaction, which finishes at some point and delivers	582
411	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
412		601
413	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
414	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,
415	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
416	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
…		…
429		618
430	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
431	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
432	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
433	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
434	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
435		624
436	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
437	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
438	for the send to occur.	627	for the send to occur.
439		628
440	Example: wait for a timer.	629	Example: wait for a timer.
441		630
442	# wait till the result is ready	631	# condition: "wait till the timer is fired"
443	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
444		633
445	# do something such as adding a timer	634	# create the timer - we could wait for, say
446	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
447	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
448	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
449	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
450	after => 1,	639	after => 1,
451	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
452	);	641	);
453		642
454	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
455	# calls send	644	# calls ->send
456	$result_ready->recv;	645	$timer_fired->recv;
457		646
458	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
459	condition variables are also code references.	648	variables are also callable directly.
460		649
461	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
462	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
463	$done->recv;	652	$done->recv;
464		653
…		…
470		659
471	...	660	...
472		661
473	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
474		663
475	And this is how you would just ste a callback to be called whenever the	664	And this is how you would just set a callback to be called whenever the
476	results are available:	665	results are available:
477		666
478	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
479	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
480	});	669	});
…		…
498	immediately from within send.	687	immediately from within send.
499		688
500	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
501	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
502		691
503	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
504	(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
505	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
506	overloading, so as tempting as it may be, passing a condition variable
507	instead of a callback does not work. Both the pure perl and EV loops
508	support overloading, however, as well as all functions that use perl to
509	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
510	example).
511		695
512	=item $cv->croak ($error)	696	=item $cv->croak ($error)
513		697
514	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
515	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
516		700
517	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
518	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.
519		707
520	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
521		709
522	=item $cv->end	710	=item $cv->end
523
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525		711
526	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
527	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
528	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
529		715
530	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
531	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
532	>>, 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
533	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
534	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.
535		722
536	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:
537		730
538	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
539		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
540	my %result;	757	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
542		759
543	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
544	$cv->begin;	761	$cv->begin;
545	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
546	$result{$host} = ...;	763	$result{$host} = ...;
…		…
561	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
562	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
563	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
564	doesn't execute once).	781	doesn't execute once).
565		782
566	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
567	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
568	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
569	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>.
570		788
571	=back	789	=back
572		790
573	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
574		792
…		…
578	=over 4	796	=over 4
579		797
580	=item $cv->recv	798	=item $cv->recv
581		799
582	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
583	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
584	normally.	802	normally.
585		803
586	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
587	will return immediately.	805	will return immediately.
588		806
…		…
590	function will call C<croak>.	808	function will call C<croak>.
591		809
592	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,
593	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
594		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
595	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
596	(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
597	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
598	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
599	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
600	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,
601	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
602		827
603	Another reason I<never> to C<< ->recv >> in a module is that you cannot
604	sensibly have two C<< ->recv >>'s in parallel, as that would require
605	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
606	can supply.
607
608	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
609	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
610	versions and also integrates coroutines into AnyEvent, making blocking
611	C<< ->recv >> calls perfectly safe as long as they are done from another
612	coroutine (one that doesn't run the event loop).
613
614	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
615	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
616	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
617	waits otherwise.	831	waits otherwise.
618		832
619	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
625		839
626	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
627	replaces it before doing so.	841	replaces it before doing so.
628		842
629	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
630	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
631	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
632	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.
633		848
634	=back	849	=back
635		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
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
638	=over 4	919	=over 4
639		920
640	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
641		922
642	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
643	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		930	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		931
669	=item AnyEvent::detect	932	=item AnyEvent::detect
670		933
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	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
673	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
674	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>.
675		945
676	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
677		947
678	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$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.
680		961
681	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
682	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
683	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 ||= $guard;
684		982
685	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
686		984
687	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
688	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
689	the event loop has been chosen.	987	after the event loop has been chosen.
690		988
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	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
693	and the array will be ignored.	991	array will be ignored.
694		992
695	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;
		1053
		1054	=item AnyEvent::log $level, $msg[, @args]
		1055
		1056	Log the given C<$msg> at the given C<$level>.
		1057
		1058	Loads AnyEvent::Log on first use and calls C<AnyEvent::Log::log> -
		1059	consequently, look at the L<AnyEvent::Log> documentation for details.
		1060
		1061	If you want to sprinkle loads of logging calls around your code, consider
		1062	creating a logger callback with the C<AnyEvent::Log::logger< function.
696		1063
697	=back	1064	=back
698		1065
699	=head1 WHAT TO DO IN A MODULE	1066	=head1 WHAT TO DO IN A MODULE
700		1067
…		…
711	because it will stall the whole program, and the whole point of using	1078	because it will stall the whole program, and the whole point of using
712	events is to stay interactive.	1079	events is to stay interactive.
713		1080
714	It is fine, however, to call C<< ->recv >> when the user of your module	1081	It is fine, however, to call C<< ->recv >> when the user of your module
715	requests it (i.e. if you create a http request object ad have a method	1082	requests it (i.e. if you create a http request object ad have a method
716	called C<results> that returns the results, it should call C<< ->recv >>	1083	called C<results> that returns the results, it may call C<< ->recv >>
717	freely, as the user of your module knows what she is doing. always).	1084	freely, as the user of your module knows what she is doing. Always).
718		1085
719	=head1 WHAT TO DO IN THE MAIN PROGRAM	1086	=head1 WHAT TO DO IN THE MAIN PROGRAM
720		1087
721	There will always be a single main program - the only place that should	1088	There will always be a single main program - the only place that should
722	dictate which event model to use.	1089	dictate which event model to use.
723		1090
724	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1091	If the program is not event-based, it need not do anything special, even
725	do anything special (it does not need to be event-based) and let AnyEvent	1092	when it depends on a module that uses an AnyEvent. If the program itself
726	decide which implementation to chose if some module relies on it.	1093	uses AnyEvent, but does not care which event loop is used, all it needs
		1094	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1095	available loop implementation.
727		1096
728	If the main program relies on a specific event model - for example, in	1097	If the main program relies on a specific event model - for example, in
729	Gtk2 programs you have to rely on the Glib module - you should load the	1098	Gtk2 programs you have to rely on the Glib module - you should load the
730	event module before loading AnyEvent or any module that uses it: generally	1099	event module before loading AnyEvent or any module that uses it: generally
731	speaking, you should load it as early as possible. The reason is that	1100	speaking, you should load it as early as possible. The reason is that
732	modules might create watchers when they are loaded, and AnyEvent will	1101	modules might create watchers when they are loaded, and AnyEvent will
733	decide on the event model to use as soon as it creates watchers, and it	1102	decide on the event model to use as soon as it creates watchers, and it
734	might chose the wrong one unless you load the correct one yourself.	1103	might choose the wrong one unless you load the correct one yourself.
735		1104
736	You can chose to use a pure-perl implementation by loading the	1105	You can chose to use a pure-perl implementation by loading the
737	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1106	C<AnyEvent::Loop> module, which gives you similar behaviour
738	everywhere, but letting AnyEvent chose the model is generally better.	1107	everywhere, but letting AnyEvent chose the model is generally better.
739		1108
740	=head2 MAINLOOP EMULATION	1109	=head2 MAINLOOP EMULATION
741		1110
742	Sometimes (often for short test scripts, or even standalone programs who	1111	Sometimes (often for short test scripts, or even standalone programs who
…		…
755		1124
756		1125
757	=head1 OTHER MODULES	1126	=head1 OTHER MODULES
758		1127
759	The following is a non-exhaustive list of additional modules that use	1128	The following is a non-exhaustive list of additional modules that use
760	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1129	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
761	in the same program. Some of the modules come with AnyEvent, some are	1130	modules and other event loops in the same program. Some of the modules
762	available via CPAN.	1131	come as part of AnyEvent, the others are available via CPAN.
763		1132
764	=over 4	1133	=over 4
765		1134
766	=item L<AnyEvent::Util>	1135	=item L<AnyEvent::Util>
767		1136
768	Contains various utility functions that replace often-used but blocking	1137	Contains various utility functions that replace often-used blocking
769	functions such as C<inet_aton> by event-/callback-based versions.	1138	functions such as C<inet_aton> with event/callback-based versions.
770		1139
771	=item L<AnyEvent::Socket>	1140	=item L<AnyEvent::Socket>
772		1141
773	Provides various utility functions for (internet protocol) sockets,	1142	Provides various utility functions for (internet protocol) sockets,
774	addresses and name resolution. Also functions to create non-blocking tcp	1143	addresses and name resolution. Also functions to create non-blocking tcp
…		…
776		1145
777	=item L<AnyEvent::Handle>	1146	=item L<AnyEvent::Handle>
778		1147
779	Provide read and write buffers, manages watchers for reads and writes,	1148	Provide read and write buffers, manages watchers for reads and writes,
780	supports raw and formatted I/O, I/O queued and fully transparent and	1149	supports raw and formatted I/O, I/O queued and fully transparent and
781	non-blocking SSL/TLS.	1150	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
782		1151
783	=item L<AnyEvent::DNS>	1152	=item L<AnyEvent::DNS>
784		1153
785	Provides rich asynchronous DNS resolver capabilities.	1154	Provides rich asynchronous DNS resolver capabilities.
786		1155
		1156	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1157
		1158	Implement event-based interfaces to the protocols of the same name (for
		1159	the curious, IGS is the International Go Server and FCP is the Freenet
		1160	Client Protocol).
		1161
		1162	=item L<AnyEvent::Handle::UDP>
		1163
		1164	Here be danger!
		1165
		1166	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1167	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1168	its use of a stream-based API with a protocol that isn't streamable, that
		1169	the only way to improve it is to delete it.
		1170
		1171	It features data corruption (but typically only under load) and general
		1172	confusion. On top, the author is not only clueless about UDP but also
		1173	fact-resistant - some gems of his understanding: "connect doesn't work
		1174	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1175	packets", "I don't need to implement proper error checking as UDP doesn't
		1176	support error checking" and so on - he doesn't even understand what's
		1177	wrong with his module when it is explained to him.
		1178
787	=item L<AnyEvent::HTTP>	1179	=item L<AnyEvent::DBI>
788		1180
789	A simple-to-use HTTP library that is capable of making a lot of concurrent	1181	Executes L<DBI> requests asynchronously in a proxy process for you,
790	HTTP requests.	1182	notifying you in an event-based way when the operation is finished.
		1183
		1184	=item L<AnyEvent::AIO>
		1185
		1186	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1187	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1188	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1189	file I/O, and much more.
791		1190
792	=item L<AnyEvent::HTTPD>	1191	=item L<AnyEvent::HTTPD>
793		1192
794	Provides a simple web application server framework.	1193	A simple embedded webserver.
795		1194
796	=item L<AnyEvent::FastPing>	1195	=item L<AnyEvent::FastPing>
797		1196
798	The fastest ping in the west.	1197	The fastest ping in the west.
799		1198
800	=item L<AnyEvent::DBI>
801
802	Executes L<DBI> requests asynchronously in a proxy process.
803
804	=item L<AnyEvent::AIO>
805
806	Truly asynchronous I/O, should be in the toolbox of every event
807	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
808	together.
809
810	=item L<AnyEvent::BDB>
811
812	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
813	L<BDB> and AnyEvent together.
814
815	=item L<AnyEvent::GPSD>
816
817	A non-blocking interface to gpsd, a daemon delivering GPS information.
818
819	=item L<AnyEvent::IGS>
820
821	A non-blocking interface to the Internet Go Server protocol (used by
822	L<App::IGS>).
823
824	=item L<Net::IRC3>
825
826	AnyEvent based IRC client module family.
827
828	=item L<Net::XMPP2>
829
830	AnyEvent based XMPP (Jabber protocol) module family.
831
832	=item L<Net::FCP>
833
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.
836
837	=item L<Event::ExecFlow>
838
839	High level API for event-based execution flow control.
840
841	=item L<Coro>	1199	=item L<Coro>
842		1200
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1201	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1202
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1203	=back
850		1204
851	=cut	1205	=cut
852		1206
853	package AnyEvent;	1207	package AnyEvent;
854		1208
855	no warnings;	1209	# basically a tuned-down version of common::sense
856	use strict;	1210	sub common_sense {
		1211	# from common:.sense 3.4
		1212	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1213	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1214	$^H |= 0x00000600;
		1215	}
857		1216
		1217	BEGIN { AnyEvent::common_sense }
		1218
858	use Carp;	1219	use Carp ();
859		1220
860	our $VERSION = 4.22;	1221	our $VERSION = '6.01';
861	our $MODEL;	1222	our $MODEL;
862		1223
863	our $AUTOLOAD;
864	our @ISA;	1224	our @ISA;
865		1225
866	our @REGISTRY;	1226	our @REGISTRY;
867		1227
868	our $WIN32;	1228	our $VERBOSE;
869		1229
870	BEGIN {	1230	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1231	require "AnyEvent/constants.pl";
872	eval "sub WIN32(){ $win32 }";
873	}
874		1232
		1233	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1234
		1235	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1236	if ${^TAINT};
		1237
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1238	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1239	}
		1240
		1241	our $MAX_SIGNAL_LATENCY = 10;
876		1242
877	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1243	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
878		1244
879	{	1245	{
880	my $idx;	1246	my $idx;
881	$PROTOCOL{$_} = ++$idx	1247	$PROTOCOL{$_} = ++$idx
882	for reverse split /\s*,\s*/,	1248	for reverse split /\s*,\s*/,
883	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1249	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
884	}	1250	}
885		1251
		1252	our @post_detect;
		1253
		1254	sub post_detect(&) {
		1255	my ($cb) = @_;
		1256
		1257	push @post_detect, $cb;
		1258
		1259	defined wantarray
		1260	? bless \$cb, "AnyEvent::Util::postdetect"
		1261	: ()
		1262	}
		1263
		1264	sub AnyEvent::Util::postdetect::DESTROY {
		1265	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1266	}
		1267
		1268	our $POSTPONE_W;
		1269	our @POSTPONE;
		1270
		1271	sub _postpone_exec {
		1272	undef $POSTPONE_W;
		1273
		1274	&{ shift @POSTPONE }
		1275	while @POSTPONE;
		1276	}
		1277
		1278	sub postpone(&) {
		1279	push @POSTPONE, shift;
		1280
		1281	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1282
		1283	()
		1284	}
		1285
		1286	sub log($$;@) {
		1287	require AnyEvent::Log;
		1288	# AnyEvent::Log overwrites this function
		1289	goto &log;
		1290	}
		1291
886	my @models = (	1292	our @models = (
887	[EV:: => AnyEvent::Impl::EV::],	1293	[EV:: => AnyEvent::Impl::EV:: , 1],
888	[Event:: => AnyEvent::Impl::Event::],	1294	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
890	# everything below here will not be autoprobed	1295	# everything below here will not (normally) be autoprobed
891	# as the pureperl backend should work everywhere	1296	# as the pure perl backend should work everywhere
892	# and is usually faster	1297	# and is usually faster
		1298	[Event:: => AnyEvent::Impl::Event::, 1],
		1299	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1300	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1301	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1302	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1303	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1304	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1305	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1306	[Prima:: => AnyEvent::Impl::POE::],
		1307	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1308	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1309	[FLTK:: => AnyEvent::Impl::FLTK2::],
900	);	1310	);
901		1311
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1312	our @isa_hook;
903		1313
904	our @post_detect;	1314	sub _isa_set {
		1315	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
905		1316
		1317	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1318	for 1 .. $#pkg;
		1319
		1320	grep $_ && $_->[1], @isa_hook
		1321	and AE::_reset ();
		1322	}
		1323
		1324	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1325	sub _isa_hook($$;$) {
		1326	my ($i, $pkg, $reset_ae) = @_;
		1327
		1328	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1329
		1330	_isa_set;
		1331	}
		1332
		1333	# all autoloaded methods reserve the complete glob, not just the method slot.
		1334	# due to bugs in perls method cache implementation.
		1335	our @methods = qw(io timer time now now_update signal child idle condvar);
		1336
906	sub post_detect(&) {	1337	sub detect() {
907	my ($cb) = @_;	1338	return $MODEL if $MODEL; # some programs keep references to detect
908		1339
909	if ($MODEL) {	1340	local $!; # for good measure
910	$cb->();	1341	local $SIG{__DIE__}; # we use eval
911		1342
912	1	1343	# free some memory
		1344	*detect = sub () { $MODEL };
		1345	# undef &func doesn't correctly update the method cache. grmbl.
		1346	# so we delete the whole glob. grmbl.
		1347	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1348	# a glob with an active sub. hrm. i hope it works, but perl is
		1349	# usually buggy in this department. sigh.
		1350	delete @{"AnyEvent::"}{@methods};
		1351	undef @methods;
		1352
		1353	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1354	my $model = $1;
		1355	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1356	if (eval "require $model") {
		1357	$MODEL = $model;
		1358	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it."
		1359	if $VERBOSE >= 7;
913	} else {	1360	} else {
914	push @post_detect, $cb;	1361	AnyEvent::log warn => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
915		1362	}
916	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"
918	: ()
919	}	1363	}
920	}
921		1364
922	sub AnyEvent::Util::PostDetect::DESTROY {	1365	# check for already loaded models
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}
925
926	sub detect() {
927	unless ($MODEL) {	1366	unless ($MODEL) {
928	no strict 'refs';	1367	for (@REGISTRY, @models) {
929	local $SIG{__DIE__};	1368	my ($package, $model) = @$_;
930		1369	if (${"$package\::VERSION"} > 0) {
931	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
932	my $model = "AnyEvent::Impl::$1";
933	if (eval "require $model") {	1370	if (eval "require $model") {
934	$MODEL = $model;	1371	$MODEL = $model;
935	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1372	AnyEvent::log 7 => "autodetected model '$model', using it."
936	} else {	1373	if $VERBOSE >= 7;
937	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1374	last;
		1375	}
938	}	1376	}
939	}	1377	}
940		1378
941	# check for already loaded models
942	unless ($MODEL) {	1379	unless ($MODEL) {
		1380	# try to autoload a model
943	for (@REGISTRY, @models) {	1381	for (@REGISTRY, @models) {
944	my ($package, $model) = @$_;	1382	my ($package, $model, $autoload) = @$_;
		1383	if (
		1384	$autoload
		1385	and eval "require $package"
945	if (${"$package\::VERSION"} > 0) {	1386	and ${"$package\::VERSION"} > 0
946	if (eval "require $model") {	1387	and eval "require $model"
		1388	) {
947	$MODEL = $model;	1389	$MODEL = $model;
948	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1390	AnyEvent::log 7 => "autoloaded model '$model', using it."
		1391	if $VERBOSE >= 7;
949	last;	1392	last;
950	}
951	}	1393	}
952	}	1394	}
953		1395
954	unless ($MODEL) {
955	# try to load a model
956
957	for (@REGISTRY, @models) {
958	my ($package, $model) = @$_;
959	if (eval "require $package"
960	and ${"$package\::VERSION"} > 0
961	and eval "require $model") {
962	$MODEL = $model;
963	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
964	last;
965	}
966	}
967
968	$MODEL	1396	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1397	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
970	}
971	}	1398	}
972
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974
975	unshift @ISA, $MODEL;
976
977	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
978
979	(shift @post_detect)->() while @post_detect;
980	}	1399	}
981		1400
		1401	# free memory only needed for probing
		1402	undef @models;
		1403	undef @REGISTRY;
		1404
		1405	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1406
		1407	# now nuke some methods that are overridden by the backend.
		1408	# SUPER usage is not allowed in these.
		1409	for (qw(time signal child idle)) {
		1410	undef &{"AnyEvent::Base::$_"}
		1411	if defined &{"$MODEL\::$_"};
		1412	}
		1413
		1414	_isa_set;
		1415
		1416	# we're officially open!
		1417
		1418	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1419	require AnyEvent::Strict;
		1420	}
		1421
		1422	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1423	require AnyEvent::Debug;
		1424	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1425	}
		1426
		1427	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1428	require AnyEvent::Socket;
		1429	require AnyEvent::Debug;
		1430
		1431	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1432	$shell =~ s/\$\$/$$/g;
		1433
		1434	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1435	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1436	}
		1437
		1438	# now the anyevent environment is set up as the user told us to, so
		1439	# call the actual user code - post detects
		1440
		1441	(shift @post_detect)->() while @post_detect;
		1442	undef @post_detect;
		1443
		1444	*post_detect = sub(&) {
		1445	shift->();
		1446
		1447	undef
		1448	};
		1449
982	$MODEL	1450	$MODEL
983	}	1451	}
984		1452
985	sub AUTOLOAD {	1453	for my $name (@methods) {
986	(my $func = $AUTOLOAD) =~ s/.*://;	1454	*$name = sub {
987		1455	detect;
988	$method{$func}	1456	# we use goto because
989	or croak "$func: not a valid method for AnyEvent objects";	1457	# a) it makes the thunk more transparent
990		1458	# b) it allows us to delete the thunk later
991	detect unless $MODEL;	1459	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
992		1460	};
993	my $class = shift;
994	$class->$func (@_);
995	}	1461	}
996		1462
997	# utility function to dup a filehandle. this is used by many backends	1463	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1464	# to support binding more than one watcher per filehandle (they usually
999	# allow only one watcher per fd, so we dup it to get a different one).	1465	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1466	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1467	my ($poll, $fh, $r, $w) = @_;
1002		1468
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1469	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1470	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1007	: $poll eq "w" ? ($w, ">")
1008	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1009		1471
1010	open my $fh2, "$mode&" . fileno $fh	1472	open my $fh2, $mode, $fh
1011	or die "cannot dup() filehandle: $!";	1473	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1474
1013	# we assume CLOEXEC is already set by perl in all important cases	1475	# we assume CLOEXEC is already set by perl in all important cases
1014		1476
1015	($fh2, $rw)	1477	($fh2, $rw)
1016	}	1478	}
1017		1479
		1480	=head1 SIMPLIFIED AE API
		1481
		1482	Starting with version 5.0, AnyEvent officially supports a second, much
		1483	simpler, API that is designed to reduce the calling, typing and memory
		1484	overhead by using function call syntax and a fixed number of parameters.
		1485
		1486	See the L<AE> manpage for details.
		1487
		1488	=cut
		1489
		1490	package AE;
		1491
		1492	our $VERSION = $AnyEvent::VERSION;
		1493
		1494	sub _reset() {
		1495	eval q{
		1496	# fall back to the main API by default - backends and AnyEvent::Base
		1497	# implementations can overwrite these.
		1498
		1499	sub io($$$) {
		1500	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1501	}
		1502
		1503	sub timer($$$) {
		1504	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1505	}
		1506
		1507	sub signal($$) {
		1508	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1509	}
		1510
		1511	sub child($$) {
		1512	AnyEvent->child (pid => $_[0], cb => $_[1])
		1513	}
		1514
		1515	sub idle($) {
		1516	AnyEvent->idle (cb => $_[0]);
		1517	}
		1518
		1519	sub cv(;&) {
		1520	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1521	}
		1522
		1523	sub now() {
		1524	AnyEvent->now
		1525	}
		1526
		1527	sub now_update() {
		1528	AnyEvent->now_update
		1529	}
		1530
		1531	sub time() {
		1532	AnyEvent->time
		1533	}
		1534
		1535	*postpone = \&AnyEvent::postpone;
		1536	*log = \&AnyEvent::log;
		1537	};
		1538	die if $@;
		1539	}
		1540
		1541	BEGIN { _reset }
		1542
1018	package AnyEvent::Base;	1543	package AnyEvent::Base;
1019		1544
1020	# default implementation for now and time	1545	# default implementations for many methods
1021		1546
1022	use Time::HiRes ();	1547	sub time {
		1548	eval q{ # poor man's autoloading {}
		1549	# probe for availability of Time::HiRes
		1550	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1551	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy."
		1552	if $AnyEvent::VERBOSE >= 8;
		1553	*time = sub { Time::HiRes::time () };
		1554	*AE::time = \& Time::HiRes::time ;
		1555	# if (eval "use POSIX (); (POSIX::times())...
		1556	} else {
		1557	AnyEvent::log critical => "using built-in time(), WARNING, no sub-second resolution!";
		1558	*time = sub { CORE::time };
		1559	*AE::time = sub (){ CORE::time };
		1560	}
1023		1561
1024	sub time { Time::HiRes::time }	1562	*now = \&time;
1025	sub now { Time::HiRes::time }	1563	};
		1564	die if $@;
		1565
		1566	&time
		1567	}
		1568
		1569	*now = \&time;
		1570	sub now_update { }
		1571
		1572	sub _poll {
		1573	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1574	}
1026		1575
1027	# default implementation for ->condvar	1576	# default implementation for ->condvar
		1577	# in fact, the default should not be overwritten
1028		1578
1029	sub condvar {	1579	sub condvar {
		1580	eval q{ # poor man's autoloading {}
		1581	*condvar = sub {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1582	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1583	};
		1584
		1585	*AE::cv = sub (;&) {
		1586	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1587	};
		1588	};
		1589	die if $@;
		1590
		1591	&condvar
1031	}	1592	}
1032		1593
1033	# default implementation for ->signal	1594	# default implementation for ->signal
1034		1595
1035	our %SIG_CB;	1596	our $HAVE_ASYNC_INTERRUPT;
		1597
		1598	sub _have_async_interrupt() {
		1599	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1600	&& eval "use Async::Interrupt 1.02 (); 1")
		1601	unless defined $HAVE_ASYNC_INTERRUPT;
		1602
		1603	$HAVE_ASYNC_INTERRUPT
		1604	}
		1605
		1606	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1607	our (%SIG_ASY, %SIG_ASY_W);
		1608	our ($SIG_COUNT, $SIG_TW);
		1609
		1610	# install a dummy wakeup watcher to reduce signal catching latency
		1611	# used by Impls
		1612	sub _sig_add() {
		1613	unless ($SIG_COUNT++) {
		1614	# try to align timer on a full-second boundary, if possible
		1615	my $NOW = AE::now;
		1616
		1617	$SIG_TW = AE::timer
		1618	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1619	$MAX_SIGNAL_LATENCY,
		1620	sub { } # just for the PERL_ASYNC_CHECK
		1621	;
		1622	}
		1623	}
		1624
		1625	sub _sig_del {
		1626	undef $SIG_TW
		1627	unless --$SIG_COUNT;
		1628	}
		1629
		1630	our $_sig_name_init; $_sig_name_init = sub {
		1631	eval q{ # poor man's autoloading {}
		1632	undef $_sig_name_init;
		1633
		1634	if (_have_async_interrupt) {
		1635	*sig2num = \&Async::Interrupt::sig2num;
		1636	*sig2name = \&Async::Interrupt::sig2name;
		1637	} else {
		1638	require Config;
		1639
		1640	my %signame2num;
		1641	@signame2num{ split ' ', $Config::Config{sig_name} }
		1642	= split ' ', $Config::Config{sig_num};
		1643
		1644	my @signum2name;
		1645	@signum2name[values %signame2num] = keys %signame2num;
		1646
		1647	*sig2num = sub($) {
		1648	$_[0] > 0 ? shift : $signame2num{+shift}
		1649	};
		1650	*sig2name = sub ($) {
		1651	$_[0] > 0 ? $signum2name[+shift] : shift
		1652	};
		1653	}
		1654	};
		1655	die if $@;
		1656	};
		1657
		1658	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1659	sub sig2name($) { &$_sig_name_init; &sig2name }
1036		1660
1037	sub signal {	1661	sub signal {
		1662	eval q{ # poor man's autoloading {}
		1663	# probe for availability of Async::Interrupt
		1664	if (_have_async_interrupt) {
		1665	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling."
		1666	if $AnyEvent::VERBOSE >= 8;
		1667
		1668	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1669	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1670
		1671	} else {
		1672	AnyEvent::log 8 => "using emulated perl signal handling with latency timer."
		1673	if $AnyEvent::VERBOSE >= 8;
		1674
		1675	if (AnyEvent::WIN32) {
		1676	require AnyEvent::Util;
		1677
		1678	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1679	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1680	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1681	} else {
		1682	pipe $SIGPIPE_R, $SIGPIPE_W;
		1683	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1684	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1685
		1686	# not strictly required, as $^F is normally 2, but let's make sure...
		1687	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1688	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1689	}
		1690
		1691	$SIGPIPE_R
		1692	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1693
		1694	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1695	}
		1696
		1697	*signal = $HAVE_ASYNC_INTERRUPT
		1698	? sub {
1038	my (undef, %arg) = @_;	1699	my (undef, %arg) = @_;
1039		1700
		1701	# async::interrupt
1040	my $signal = uc $arg{signal}	1702	my $signal = sig2num $arg{signal};
1041	or Carp::croak "required option 'signal' is missing";
1042
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1703	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1704
		1705	$SIG_ASY{$signal} ||= new Async::Interrupt
		1706	cb => sub { undef $SIG_EV{$signal} },
		1707	signal => $signal,
		1708	pipe => [$SIGPIPE_R->filenos],
		1709	pipe_autodrain => 0,
		1710	;
		1711
		1712	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1713	}
		1714	: sub {
		1715	my (undef, %arg) = @_;
		1716
		1717	# pure perl
		1718	my $signal = sig2name $arg{signal};
		1719	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1720
1044	$SIG{$signal} ||= sub {	1721	$SIG{$signal} ||= sub {
		1722	local $!;
		1723	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1724	undef $SIG_EV{$signal};
		1725	};
		1726
		1727	# can't do signal processing without introducing races in pure perl,
		1728	# so limit the signal latency.
		1729	_sig_add;
		1730
		1731	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1732	}
		1733	;
		1734
		1735	*AnyEvent::Base::signal::DESTROY = sub {
		1736	my ($signal, $cb) = @{$_[0]};
		1737
		1738	_sig_del;
		1739
		1740	delete $SIG_CB{$signal}{$cb};
		1741
		1742	$HAVE_ASYNC_INTERRUPT
		1743	? delete $SIG_ASY{$signal}
		1744	: # delete doesn't work with older perls - they then
		1745	# print weird messages, or just unconditionally exit
		1746	# instead of getting the default action.
		1747	undef $SIG{$signal}
		1748	unless keys %{ $SIG_CB{$signal} };
		1749	};
		1750
		1751	*_signal_exec = sub {
		1752	$HAVE_ASYNC_INTERRUPT
		1753	? $SIGPIPE_R->drain
		1754	: sysread $SIGPIPE_R, (my $dummy), 9;
		1755
		1756	while (%SIG_EV) {
		1757	for (keys %SIG_EV) {
		1758	delete $SIG_EV{$_};
1045	$_->() for values %{ $SIG_CB{$signal} || {} };	1759	&$_ for values %{ $SIG_CB{$_} || {} };
		1760	}
		1761	}
		1762	};
1046	};	1763	};
		1764	die if $@;
1047		1765
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1766	&signal
1049	}
1050
1051	sub AnyEvent::Base::Signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};
1053
1054	delete $SIG_CB{$signal}{$cb};
1055
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1057	}	1767	}
1058		1768
1059	# default implementation for ->child	1769	# default implementation for ->child
1060		1770
1061	our %PID_CB;	1771	our %PID_CB;
1062	our $CHLD_W;	1772	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1773	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;
1066		1774
1067	sub _child_wait {	1775	# used by many Impl's
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1776	sub _emit_childstatus($$) {
		1777	my (undef, $rpid, $rstatus) = @_;
		1778
		1779	$_->($rpid, $rstatus)
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1780	for values %{ $PID_CB{$rpid} || {} },
1070	(values %{ $PID_CB{0} || {} });	1781	values %{ $PID_CB{0} || {} };
1071	}
1072
1073	undef $PID_IDLE;
1074	}
1075
1076	sub _sigchld {
1077	# make sure we deliver these changes "synchronous" with the event loop.
1078	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1079	undef $CHLD_DELAY_W;
1080	&_child_wait;
1081	});
1082	}	1782	}
1083		1783
1084	sub child {	1784	sub child {
		1785	eval q{ # poor man's autoloading {}
		1786	*_sigchld = sub {
		1787	my $pid;
		1788
		1789	AnyEvent->_emit_childstatus ($pid, $?)
		1790	while ($pid = waitpid -1, WNOHANG) > 0;
		1791	};
		1792
		1793	*child = sub {
1085	my (undef, %arg) = @_;	1794	my (undef, %arg) = @_;
1086		1795
1087	defined (my $pid = $arg{pid} + 0)	1796	my $pid = $arg{pid};
1088	or Carp::croak "required option 'pid' is missing";	1797	my $cb = $arg{cb};
1089		1798
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1799	$PID_CB{$pid}{$cb+0} = $cb;
1091		1800
1092	unless ($WNOHANG) {
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094	}
1095
1096	unless ($CHLD_W) {	1801	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1802	$CHLD_W = AE::signal CHLD => \&_sigchld;
1098	# child could be a zombie already, so make at least one round	1803	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1804	&_sigchld;
1100	}	1805	}
1101		1806
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1807	bless [$pid, $cb+0], "AnyEvent::Base::child"
1103	}	1808	};
1104		1809
1105	sub AnyEvent::Base::Child::DESTROY {	1810	*AnyEvent::Base::child::DESTROY = sub {
1106	my ($pid, $cb) = @{$_[0]};	1811	my ($pid, $icb) = @{$_[0]};
1107		1812
1108	delete $PID_CB{$pid}{$cb};	1813	delete $PID_CB{$pid}{$icb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1814	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1815
1111	undef $CHLD_W unless keys %PID_CB;	1816	undef $CHLD_W unless keys %PID_CB;
		1817	};
		1818	};
		1819	die if $@;
		1820
		1821	&child
		1822	}
		1823
		1824	# idle emulation is done by simply using a timer, regardless
		1825	# of whether the process is idle or not, and not letting
		1826	# the callback use more than 50% of the time.
		1827	sub idle {
		1828	eval q{ # poor man's autoloading {}
		1829	*idle = sub {
		1830	my (undef, %arg) = @_;
		1831
		1832	my ($cb, $w, $rcb) = $arg{cb};
		1833
		1834	$rcb = sub {
		1835	if ($cb) {
		1836	$w = AE::time;
		1837	&$cb;
		1838	$w = AE::time - $w;
		1839
		1840	# never use more then 50% of the time for the idle watcher,
		1841	# within some limits
		1842	$w = 0.0001 if $w < 0.0001;
		1843	$w = 5 if $w > 5;
		1844
		1845	$w = AE::timer $w, 0, $rcb;
		1846	} else {
		1847	# clean up...
		1848	undef $w;
		1849	undef $rcb;
		1850	}
		1851	};
		1852
		1853	$w = AE::timer 0.05, 0, $rcb;
		1854
		1855	bless \\$cb, "AnyEvent::Base::idle"
		1856	};
		1857
		1858	*AnyEvent::Base::idle::DESTROY = sub {
		1859	undef $${$_[0]};
		1860	};
		1861	};
		1862	die if $@;
		1863
		1864	&idle
1112	}	1865	}
1113		1866
1114	package AnyEvent::CondVar;	1867	package AnyEvent::CondVar;
1115		1868
1116	our @ISA = AnyEvent::CondVar::Base::;	1869	our @ISA = AnyEvent::CondVar::Base::;
1117		1870
		1871	# only to be used for subclassing
		1872	sub new {
		1873	my $class = shift;
		1874	bless AnyEvent->condvar (@_), $class
		1875	}
		1876
1118	package AnyEvent::CondVar::Base;	1877	package AnyEvent::CondVar::Base;
1119		1878
1120	use overload	1879	#use overload
1121	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1880	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1122	fallback => 1;	1881	# fallback => 1;
		1882
		1883	# save 300+ kilobytes by dirtily hardcoding overloading
		1884	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1885	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1886	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1887	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1888
		1889	our $WAITING;
1123		1890
1124	sub _send {	1891	sub _send {
1125	# nop	1892	# nop
		1893	}
		1894
		1895	sub _wait {
		1896	AnyEvent->_poll until $_[0]{_ae_sent};
1126	}	1897	}
1127		1898
1128	sub send {	1899	sub send {
1129	my $cv = shift;	1900	my $cv = shift;
1130	$cv->{_ae_sent} = [@_];	1901	$cv->{_ae_sent} = [@_];
…		…
1139		1910
1140	sub ready {	1911	sub ready {
1141	$_[0]{_ae_sent}	1912	$_[0]{_ae_sent}
1142	}	1913	}
1143		1914
1144	sub _wait {
1145	AnyEvent->one_event while !$_[0]{_ae_sent};
1146	}
1147
1148	sub recv {	1915	sub recv {
		1916	unless ($_[0]{_ae_sent}) {
		1917	$WAITING
		1918	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1919
		1920	local $WAITING = 1;
1149	$_[0]->_wait;	1921	$_[0]->_wait;
		1922	}
1150		1923
1151	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1924	$_[0]{_ae_croak}
1152	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1925	and Carp::croak $_[0]{_ae_croak};
		1926
		1927	wantarray
		1928	? @{ $_[0]{_ae_sent} }
		1929	: $_[0]{_ae_sent}[0]
1153	}	1930	}
1154		1931
1155	sub cb {	1932	sub cb {
1156	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1933	my $cv = shift;
		1934
		1935	@_
		1936	and $cv->{_ae_cb} = shift
		1937	and $cv->{_ae_sent}
		1938	and (delete $cv->{_ae_cb})->($cv);
		1939
1157	$_[0]{_ae_cb}	1940	$cv->{_ae_cb}
1158	}	1941	}
1159		1942
1160	sub begin {	1943	sub begin {
1161	++$_[0]{_ae_counter};	1944	++$_[0]{_ae_counter};
1162	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1945	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1167	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1950	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1168	}	1951	}
1169		1952
1170	# undocumented/compatibility with pre-3.4	1953	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1954	*broadcast = \&send;
1172	*wait = \&_wait;	1955	*wait = \&recv;
		1956
		1957	=head1 ERROR AND EXCEPTION HANDLING
		1958
		1959	In general, AnyEvent does not do any error handling - it relies on the
		1960	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1961	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1962	checking of all AnyEvent methods, however, which is highly useful during
		1963	development.
		1964
		1965	As for exception handling (i.e. runtime errors and exceptions thrown while
		1966	executing a callback), this is not only highly event-loop specific, but
		1967	also not in any way wrapped by this module, as this is the job of the main
		1968	program.
		1969
		1970	The pure perl event loop simply re-throws the exception (usually
		1971	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1972	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1973	so on.
		1974
		1975	=head1 ENVIRONMENT VARIABLES
		1976
		1977	The following environment variables are used by this module or its
		1978	submodules.
		1979
		1980	Note that AnyEvent will remove I<all> environment variables starting with
		1981	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1982	enabled.
		1983
		1984	=over 4
		1985
		1986	=item C<PERL_ANYEVENT_VERBOSE>
		1987
		1988	By default, AnyEvent will be completely silent except in fatal
		1989	conditions. You can set this environment variable to make AnyEvent more
		1990	talkative.
		1991
		1992	When set to C<5> or higher, causes AnyEvent to warn about unexpected
		1993	conditions, such as not being able to load the event model specified by
		1994	C<PERL_ANYEVENT_MODEL>.
		1995
		1996	When set to C<7> or higher, cause AnyEvent to report to STDERR which event
		1997	model it chooses.
		1998
		1999	When set to C<8> or higher, then AnyEvent will report extra information on
		2000	which optional modules it loads and how it implements certain features.
		2001
		2002	=item C<PERL_ANYEVENT_STRICT>
		2003
		2004	AnyEvent does not do much argument checking by default, as thorough
		2005	argument checking is very costly. Setting this variable to a true value
		2006	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		2007	check the arguments passed to most method calls. If it finds any problems,
		2008	it will croak.
		2009
		2010	In other words, enables "strict" mode.
		2011
		2012	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2013	>>, it is definitely recommended to keep it off in production. Keeping
		2014	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2015	can be very useful, however.
		2016
		2017	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2018
		2019	If this env variable is set, then its contents will be interpreted by
		2020	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		2021	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		2022	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		2023
		2024	This takes place when the first watcher is created.
		2025
		2026	For example, to bind a debug shell on a unix domain socket in
		2027	F<< /tmp/debug<pid>.sock >>, you could use this:
		2028
		2029	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2030
		2031	Note that creating sockets in F</tmp> is very unsafe on multiuser
		2032	systems.
		2033
		2034	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2035
		2036	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2037	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2038
		2039	=item C<PERL_ANYEVENT_MODEL>
		2040
		2041	This can be used to specify the event model to be used by AnyEvent, before
		2042	auto detection and -probing kicks in.
		2043
		2044	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2045	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2046	resulting module name is loaded and - if the load was successful - used as
		2047	event model backend. If it fails to load then AnyEvent will proceed with
		2048	auto detection and -probing.
		2049
		2050	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2051	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2052	the end of a string designates a module name and quotes it appropriately).
		2053
		2054	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2055	could start your program like this:
		2056
		2057	PERL_ANYEVENT_MODEL=Perl perl ...
		2058
		2059	=item C<PERL_ANYEVENT_PROTOCOLS>
		2060
		2061	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2062	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2063	of auto probing).
		2064
		2065	Must be set to a comma-separated list of protocols or address families,
		2066	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2067	used, and preference will be given to protocols mentioned earlier in the
		2068	list.
		2069
		2070	This variable can effectively be used for denial-of-service attacks
		2071	against local programs (e.g. when setuid), although the impact is likely
		2072	small, as the program has to handle conenction and other failures anyways.
		2073
		2074	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2075	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2076	- only support IPv4, never try to resolve or contact IPv6
		2077	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2078	IPv6, but prefer IPv6 over IPv4.
		2079
		2080	=item C<PERL_ANYEVENT_EDNS0>
		2081
		2082	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		2083	for DNS. This extension is generally useful to reduce DNS traffic, but
		2084	some (broken) firewalls drop such DNS packets, which is why it is off by
		2085	default.
		2086
		2087	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2088	EDNS0 in its DNS requests.
		2089
		2090	=item C<PERL_ANYEVENT_MAX_FORKS>
		2091
		2092	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2093	will create in parallel.
		2094
		2095	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2096
		2097	The default value for the C<max_outstanding> parameter for the default DNS
		2098	resolver - this is the maximum number of parallel DNS requests that are
		2099	sent to the DNS server.
		2100
		2101	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2102
		2103	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2104	configuration) in the default resolver. When set to the empty string, no
		2105	default config will be used.
		2106
		2107	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2108
		2109	When neither C<ca_file> nor C<ca_path> was specified during
		2110	L<AnyEvent::TLS> context creation, and either of these environment
		2111	variables exist, they will be used to specify CA certificate locations
		2112	instead of a system-dependent default.
		2113
		2114	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2115
		2116	When these are set to C<1>, then the respective modules are not
		2117	loaded. Mostly good for testing AnyEvent itself.
		2118
		2119	=back
1173		2120
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2121	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		2122
1176	This is an advanced topic that you do not normally need to use AnyEvent in	2123	This is an advanced topic that you do not normally need to use AnyEvent in
1177	a module. This section is only of use to event loop authors who want to	2124	a module. This section is only of use to event loop authors who want to
…		…
1211		2158
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2159	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	2160	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	2161	C<die>. This still works with most modules/usages, and blocking calls must
1215	not be done in an interactive application, so it makes sense.	2162	not be done in an interactive application, so it makes sense.
1216
1217	=head1 ENVIRONMENT VARIABLES
1218
1219	The following environment variables are used by this module:
1220
1221	=over 4
1222
1223	=item C<PERL_ANYEVENT_VERBOSE>
1224
1225	By default, AnyEvent will be completely silent except in fatal
1226	conditions. You can set this environment variable to make AnyEvent more
1227	talkative.
1228
1229	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1230	conditions, such as not being able to load the event model specified by
1231	C<PERL_ANYEVENT_MODEL>.
1232
1233	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1234	model it chooses.
1235
1236	=item C<PERL_ANYEVENT_STRICT>
1237
1238	AnyEvent does not do much argument checking by default, as thorough
1239	argument checking is very costly. Setting this variable to a true value
1240	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1241	check the arguments passed to most method calls. If it finds any problems
1242	it will croak.
1243
1244	In other words, enables "strict" mode.
1245
1246	Unlike C<use strict> it is definitely recommended ot keep it off in
1247	production.
1248
1249	=item C<PERL_ANYEVENT_MODEL>
1250
1251	This can be used to specify the event model to be used by AnyEvent, before
1252	auto detection and -probing kicks in. It must be a string consisting
1253	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1254	and the resulting module name is loaded and if the load was successful,
1255	used as event model. If it fails to load AnyEvent will proceed with
1256	auto detection and -probing.
1257
1258	This functionality might change in future versions.
1259
1260	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1261	could start your program like this:
1262
1263	PERL_ANYEVENT_MODEL=Perl perl ...
1264
1265	=item C<PERL_ANYEVENT_PROTOCOLS>
1266
1267	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1268	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1269	of auto probing).
1270
1271	Must be set to a comma-separated list of protocols or address families,
1272	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1273	used, and preference will be given to protocols mentioned earlier in the
1274	list.
1275
1276	This variable can effectively be used for denial-of-service attacks
1277	against local programs (e.g. when setuid), although the impact is likely
1278	small, as the program has to handle connection errors already-
1279
1280	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1281	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1282	- only support IPv4, never try to resolve or contact IPv6
1283	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1284	IPv6, but prefer IPv6 over IPv4.
1285
1286	=item C<PERL_ANYEVENT_EDNS0>
1287
1288	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1289	for DNS. This extension is generally useful to reduce DNS traffic, but
1290	some (broken) firewalls drop such DNS packets, which is why it is off by
1291	default.
1292
1293	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1294	EDNS0 in its DNS requests.
1295
1296	=item C<PERL_ANYEVENT_MAX_FORKS>
1297
1298	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1299	will create in parallel.
1300
1301	=back
1302		2163
1303	=head1 EXAMPLE PROGRAM	2164	=head1 EXAMPLE PROGRAM
1304		2165
1305	The following program uses an I/O watcher to read data from STDIN, a timer	2166	The following program uses an I/O watcher to read data from STDIN, a timer
1306	to display a message once per second, and a condition variable to quit the	2167	to display a message once per second, and a condition variable to quit the
…		…
1319	warn "read: $input\n"; # output what has been read	2180	warn "read: $input\n"; # output what has been read
1320	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2181	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1321	},	2182	},
1322	);	2183	);
1323		2184
1324	my $time_watcher; # can only be used once
1325
1326	sub new_timer {
1327	$timer = AnyEvent->timer (after => 1, cb => sub {	2185	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1328	warn "timeout\n"; # print 'timeout' about every second	2186	warn "timeout\n"; # print 'timeout' at most every second
1329	&new_timer; # and restart the time
1330	});	2187	});
1331	}
1332
1333	new_timer; # create first timer
1334		2188
1335	$cv->recv; # wait until user enters /^q/i	2189	$cv->recv; # wait until user enters /^q/i
1336		2190
1337	=head1 REAL-WORLD EXAMPLE	2191	=head1 REAL-WORLD EXAMPLE
1338		2192
…		…
1411		2265
1412	The actual code goes further and collects all errors (C<die>s, exceptions)	2266	The actual code goes further and collects all errors (C<die>s, exceptions)
1413	that occurred during request processing. The C<result> method detects	2267	that occurred during request processing. The C<result> method detects
1414	whether an exception as thrown (it is stored inside the $txn object)	2268	whether an exception as thrown (it is stored inside the $txn object)
1415	and just throws the exception, which means connection errors and other	2269	and just throws the exception, which means connection errors and other
1416	problems get reported tot he code that tries to use the result, not in a	2270	problems get reported to the code that tries to use the result, not in a
1417	random callback.	2271	random callback.
1418		2272
1419	All of this enables the following usage styles:	2273	All of this enables the following usage styles:
1420		2274
1421	1. Blocking:	2275	1. Blocking:
…		…
1469	through AnyEvent. The benchmark creates a lot of timers (with a zero	2323	through AnyEvent. The benchmark creates a lot of timers (with a zero
1470	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2324	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1471	which it is), lets them fire exactly once and destroys them again.	2325	which it is), lets them fire exactly once and destroys them again.
1472		2326
1473	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2327	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1474	distribution.	2328	distribution. It uses the L<AE> interface, which makes a real difference
		2329	for the EV and Perl backends only.
1475		2330
1476	=head3 Explanation of the columns	2331	=head3 Explanation of the columns
1477		2332
1478	I<watcher> is the number of event watchers created/destroyed. Since	2333	I<watcher> is the number of event watchers created/destroyed. Since
1479	different event models feature vastly different performances, each event	2334	different event models feature vastly different performances, each event
…		…
1500	watcher.	2355	watcher.
1501		2356
1502	=head3 Results	2357	=head3 Results
1503		2358
1504	name watchers bytes create invoke destroy comment	2359	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2360	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1506	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2361	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1507	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2362	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1508	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2363	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1509	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2364	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1510	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2365	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2366	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2367	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1511	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2368	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1512	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2369	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1513	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2370	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1514	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2371	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1515		2372
1516	=head3 Discussion	2373	=head3 Discussion
1517		2374
1518	The benchmark does I<not> measure scalability of the event loop very	2375	The benchmark does I<not> measure scalability of the event loop very
1519	well. For example, a select-based event loop (such as the pure perl one)	2376	well. For example, a select-based event loop (such as the pure perl one)
…		…
1531	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2388	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1532	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2389	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1533	cycles with POE.	2390	cycles with POE.
1534		2391
1535	C<EV> is the sole leader regarding speed and memory use, which are both	2392	C<EV> is the sole leader regarding speed and memory use, which are both
1536	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2393	maximal/minimal, respectively. When using the L<AE> API there is zero
		2394	overhead (when going through the AnyEvent API create is about 5-6 times
		2395	slower, with other times being equal, so still uses far less memory than
1537	far less memory than any other event loop and is still faster than Event	2396	any other event loop and is still faster than Event natively).
1538	natively.
1539		2397
1540	The pure perl implementation is hit in a few sweet spots (both the	2398	The pure perl implementation is hit in a few sweet spots (both the
1541	constant timeout and the use of a single fd hit optimisations in the perl	2399	constant timeout and the use of a single fd hit optimisations in the perl
1542	interpreter and the backend itself). Nevertheless this shows that it	2400	interpreter and the backend itself). Nevertheless this shows that it
1543	adds very little overhead in itself. Like any select-based backend its	2401	adds very little overhead in itself. Like any select-based backend its
1544	performance becomes really bad with lots of file descriptors (and few of	2402	performance becomes really bad with lots of file descriptors (and few of
1545	them active), of course, but this was not subject of this benchmark.	2403	them active), of course, but this was not subject of this benchmark.
1546		2404
1547	The C<Event> module has a relatively high setup and callback invocation	2405	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	2406	cost, but overall scores in on the third place.
		2407
		2408	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2409	when using its pure perl backend.
1549		2410
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	2411	C<Glib>'s memory usage is quite a bit higher, but it features a
1551	faster callback invocation and overall ends up in the same class as	2412	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	2413	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	2414	watchers increases the processing time by more than a factor of four,
…		…
1588	(even when used without AnyEvent), but most event loops have acceptable	2449	(even when used without AnyEvent), but most event loops have acceptable
1589	performance with or without AnyEvent.	2450	performance with or without AnyEvent.
1590		2451
1591	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2452	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1592	the actual event loop, only with extremely fast event loops such as EV	2453	the actual event loop, only with extremely fast event loops such as EV
1593	adds AnyEvent significant overhead.	2454	does AnyEvent add significant overhead.
1594		2455
1595	=item * You should avoid POE like the plague if you want performance or	2456	=item * You should avoid POE like the plague if you want performance or
1596	reasonable memory usage.	2457	reasonable memory usage.
1597		2458
1598	=back	2459	=back
…		…
1614	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2475	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1615	(1%) are active. This mirrors the activity of large servers with many	2476	(1%) are active. This mirrors the activity of large servers with many
1616	connections, most of which are idle at any one point in time.	2477	connections, most of which are idle at any one point in time.
1617		2478
1618	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2479	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1619	distribution.	2480	distribution. It uses the L<AE> interface, which makes a real difference
		2481	for the EV and Perl backends only.
1620		2482
1621	=head3 Explanation of the columns	2483	=head3 Explanation of the columns
1622		2484
1623	I<sockets> is the number of sockets, and twice the number of "servers" (as	2485	I<sockets> is the number of sockets, and twice the number of "servers" (as
1624	each server has a read and write socket end).	2486	each server has a read and write socket end).
…		…
1631	it to another server. This includes deleting the old timeout and creating	2493	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	2494	a new one that moves the timeout into the future.
1633		2495
1634	=head3 Results	2496	=head3 Results
1635		2497
1636	name sockets create request	2498	name sockets create request
1637	EV 20000 69.01 11.16	2499	EV 20000 62.66 7.99
1638	Perl 20000 73.32 35.87	2500	Perl 20000 68.32 32.64
1639	Event 20000 212.62 257.32	2501	IOAsync 20000 174.06 101.15 epoll
1640	Glib 20000 651.16 1896.30	2502	IOAsync 20000 174.67 610.84 poll
		2503	Event 20000 202.69 242.91
		2504	Glib 20000 557.01 1689.52
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	2505	POE 20000 341.54 12086.32 uses POE::Loop::Event
1642		2506
1643	=head3 Discussion	2507	=head3 Discussion
1644		2508
1645	This benchmark I<does> measure scalability and overall performance of the	2509	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	2510	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	2512	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	2513	is relatively high, though.
1650		2514
1651	Perl surprisingly comes second. It is much faster than the C-based event	2515	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	2516	loops Event and Glib.
		2517
		2518	IO::Async performs very well when using its epoll backend, and still quite
		2519	good compared to Glib when using its pure perl backend.
1653		2520
1654	Event suffers from high setup time as well (look at its code and you will	2521	Event suffers from high setup time as well (look at its code and you will
1655	understand why). Callback invocation also has a high overhead compared to	2522	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2523	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	2524	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2587	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2588	watchers, as the management overhead dominates.
1722		2589
1723	=back	2590	=back
1724		2591
		2592	=head2 THE IO::Lambda BENCHMARK
		2593
		2594	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2595	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2596	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2597	shouldn't come as a surprise to anybody). As such, the benchmark is
		2598	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2599	very optimal. But how would AnyEvent compare when used without the extra
		2600	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2601
		2602	The benchmark itself creates an echo-server, and then, for 500 times,
		2603	connects to the echo server, sends a line, waits for the reply, and then
		2604	creates the next connection. This is a rather bad benchmark, as it doesn't
		2605	test the efficiency of the framework or much non-blocking I/O, but it is a
		2606	benchmark nevertheless.
		2607
		2608	name runtime
		2609	Lambda/select 0.330 sec
		2610	+ optimized 0.122 sec
		2611	Lambda/AnyEvent 0.327 sec
		2612	+ optimized 0.138 sec
		2613	Raw sockets/select 0.077 sec
		2614	POE/select, components 0.662 sec
		2615	POE/select, raw sockets 0.226 sec
		2616	POE/select, optimized 0.404 sec
		2617
		2618	AnyEvent/select/nb 0.085 sec
		2619	AnyEvent/EV/nb 0.068 sec
		2620	+state machine 0.134 sec
		2621
		2622	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2623	benchmarks actually make blocking connects and use 100% blocking I/O,
		2624	defeating the purpose of an event-based solution. All of the newly
		2625	written AnyEvent benchmarks use 100% non-blocking connects (using
		2626	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2627	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2628	generally require a lot more bookkeeping and event handling than blocking
		2629	connects (which involve a single syscall only).
		2630
		2631	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2632	offers similar expressive power as POE and IO::Lambda, using conventional
		2633	Perl syntax. This means that both the echo server and the client are 100%
		2634	non-blocking, further placing it at a disadvantage.
		2635
		2636	As you can see, the AnyEvent + EV combination even beats the
		2637	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2638	backend easily beats IO::Lambda and POE.
		2639
		2640	And even the 100% non-blocking version written using the high-level (and
		2641	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2642	higher level ("unoptimised") abstractions by a large margin, even though
		2643	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2644
		2645	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2646	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2647	part of the IO::Lambda distribution and were used without any changes.
		2648
		2649
		2650	=head1 SIGNALS
		2651
		2652	AnyEvent currently installs handlers for these signals:
		2653
		2654	=over 4
		2655
		2656	=item SIGCHLD
		2657
		2658	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2659	emulation for event loops that do not support them natively. Also, some
		2660	event loops install a similar handler.
		2661
		2662	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2663	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2664
		2665	=item SIGPIPE
		2666
		2667	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2668	when AnyEvent gets loaded.
		2669
		2670	The rationale for this is that AnyEvent users usually do not really depend
		2671	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2672	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2673	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2674	some random socket.
		2675
		2676	The rationale for installing a no-op handler as opposed to ignoring it is
		2677	that this way, the handler will be restored to defaults on exec.
		2678
		2679	Feel free to install your own handler, or reset it to defaults.
		2680
		2681	=back
		2682
		2683	=cut
		2684
		2685	undef $SIG{CHLD}
		2686	if $SIG{CHLD} eq 'IGNORE';
		2687
		2688	$SIG{PIPE} = sub { }
		2689	unless defined $SIG{PIPE};
		2690
		2691	=head1 RECOMMENDED/OPTIONAL MODULES
		2692
		2693	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2694	its built-in modules) are required to use it.
		2695
		2696	That does not mean that AnyEvent won't take advantage of some additional
		2697	modules if they are installed.
		2698
		2699	This section explains which additional modules will be used, and how they
		2700	affect AnyEvent's operation.
		2701
		2702	=over 4
		2703
		2704	=item L<Async::Interrupt>
		2705
		2706	This slightly arcane module is used to implement fast signal handling: To
		2707	my knowledge, there is no way to do completely race-free and quick
		2708	signal handling in pure perl. To ensure that signals still get
		2709	delivered, AnyEvent will start an interval timer to wake up perl (and
		2710	catch the signals) with some delay (default is 10 seconds, look for
		2711	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2712
		2713	If this module is available, then it will be used to implement signal
		2714	catching, which means that signals will not be delayed, and the event loop
		2715	will not be interrupted regularly, which is more efficient (and good for
		2716	battery life on laptops).
		2717
		2718	This affects not just the pure-perl event loop, but also other event loops
		2719	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2720
		2721	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2722	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2723	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2724	does nothing for those backends.
		2725
		2726	=item L<EV>
		2727
		2728	This module isn't really "optional", as it is simply one of the backend
		2729	event loops that AnyEvent can use. However, it is simply the best event
		2730	loop available in terms of features, speed and stability: It supports
		2731	the AnyEvent API optimally, implements all the watcher types in XS, does
		2732	automatic timer adjustments even when no monotonic clock is available,
		2733	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2734	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2735	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2736
		2737	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2738	then this module will do nothing for you.
		2739
		2740	=item L<Guard>
		2741
		2742	The guard module, when used, will be used to implement
		2743	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2744	lot less memory), but otherwise doesn't affect guard operation much. It is
		2745	purely used for performance.
		2746
		2747	=item L<JSON> and L<JSON::XS>
		2748
		2749	One of these modules is required when you want to read or write JSON data
		2750	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2751	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2752
		2753	=item L<Net::SSLeay>
		2754
		2755	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2756	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2757	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2758
		2759	=item L<Time::HiRes>
		2760
		2761	This module is part of perl since release 5.008. It will be used when the
		2762	chosen event library does not come with a timing source of its own. The
		2763	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2764	try to use a monotonic clock for timing stability.
		2765
		2766	=back
		2767
1725		2768
1726	=head1 FORK	2769	=head1 FORK
1727		2770
1728	Most event libraries are not fork-safe. The ones who are usually are	2771	Most event libraries are not fork-safe. The ones who are usually are
1729	because they rely on inefficient but fork-safe C<select> or C<poll>	2772	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1730	calls. Only L<EV> is fully fork-aware.	2773	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2774	are usually badly thought-out hacks that are incompatible with fork in
		2775	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2776	continue event-processing in both parent and child (or both, if you know
		2777	what you are doing).
		2778
		2779	This means that, in general, you cannot fork and do event processing in
		2780	the child if the event library was initialised before the fork (which
		2781	usually happens when the first AnyEvent watcher is created, or the library
		2782	is loaded).
1731		2783
1732	If you have to fork, you must either do so I<before> creating your first	2784	If you have to fork, you must either do so I<before> creating your first
1733	watcher OR you must not use AnyEvent at all in the child.	2785	watcher OR you must not use AnyEvent at all in the child OR you must do
		2786	something completely out of the scope of AnyEvent.
		2787
		2788	The problem of doing event processing in the parent I<and> the child
		2789	is much more complicated: even for backends that I<are> fork-aware or
		2790	fork-safe, their behaviour is not usually what you want: fork clones all
		2791	watchers, that means all timers, I/O watchers etc. are active in both
		2792	parent and child, which is almost never what you want. USing C<exec>
		2793	to start worker children from some kind of manage rprocess is usually
		2794	preferred, because it is much easier and cleaner, at the expense of having
		2795	to have another binary.
1734		2796
1735		2797
1736	=head1 SECURITY CONSIDERATIONS	2798	=head1 SECURITY CONSIDERATIONS
1737		2799
1738	AnyEvent can be forced to load any event model via	2800	AnyEvent can be forced to load any event model via
…		…
1750	use AnyEvent;	2812	use AnyEvent;
1751		2813
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2814	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1753	be used to probe what backend is used and gain other information (which is	2815	be used to probe what backend is used and gain other information (which is
1754	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2816	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2817	$ENV{PERL_ANYEVENT_STRICT}.
		2818
		2819	Note that AnyEvent will remove I<all> environment variables starting with
		2820	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2821	enabled.
1756		2822
1757		2823
1758	=head1 BUGS	2824	=head1 BUGS
1759		2825
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2826	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1761	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2827	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1762	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2828	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1763	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2829	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2830	pronounced).
1765		2831
1766		2832
1767	=head1 SEE ALSO	2833	=head1 SEE ALSO
1768		2834
1769	Utility functions: L<AnyEvent::Util>.	2835	Tutorial/Introduction: L<AnyEvent::Intro>.
1770		2836
1771	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2837	FAQ: L<AnyEvent::FAQ>.
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2838
		2839	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2840	(simply logging).
		2841
		2842	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2843	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2844
		2845	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2846	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2847	L<Qt>, L<POE>, L<FLTK>.
1773		2848
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2849	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2850	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2851	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		2852	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1777	L<AnyEvent::Impl::POE>.	2853	L<AnyEvent::Impl::FLTK>.
1778		2854
1779	Non-blocking file handles, sockets, TCP clients and	2855	Non-blocking handles, pipes, stream sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2856	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2857
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2858	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2859
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2860	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1785		2861
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2862	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2863	L<AnyEvent::HTTP>.
1787		2864
1788		2865
1789	=head1 AUTHOR	2866	=head1 AUTHOR
1790		2867
1791	Marc Lehmann <schmorp@schmorp.de>	2868	Marc Lehmann <schmorp@schmorp.de>

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