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Revision 1.360 by root, Sat Aug 13 22:44:05 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 and POE are various supported	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
6	event loops.	6	and POE are various supported event loops/environments.
7		7
8	=head1 SYNOPSIS	8	=head1 SYNOPSIS
9		9
10	use AnyEvent;	10	use AnyEvent;
11		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
12	# file descriptor readable	15	# file handle or descriptor readable
13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
14		17
15	# one-shot or repeating timers	18	# one-shot or repeating timers
16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
18		21
19	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
21		24
22	# POSIX signal	25	# POSIX signal
…		…
40	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
41		44
42	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
43	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
44	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.
45		58
46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
47		60
48	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
49	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
65	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
66	model you use.	79	model you use.
67		80
68	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
69	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
70	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
71	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
72	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
73	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.
74		87
75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
76	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
77	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
78	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
79	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
80	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
81	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,
82	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
83		96
84	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
85	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
86	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
87	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
88	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
89	technically possible.	102	technically possible.
90		103
91	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
92	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
98	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
99	model, you should I<not> use this module.	112	model, you should I<not> use this module.
100		113
101	=head1 DESCRIPTION	114	=head1 DESCRIPTION
102		115
103	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
104	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
105	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
106	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
107		120
108	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>
109	module.	122	module.
110		123
111	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
112	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
113	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
114	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
115	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
116	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
117	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
118	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
119	found, AnyEvent will fall back to a pure-perl event loop, which is not
120	very efficient, but should work everywhere.
121		132
122	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
123	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
124	that model the default. For example:	135	that model the default. For example:
125		136
…		…
127	use AnyEvent;	138	use AnyEvent;
128		139
129	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
130		141
131	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
132	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,
133	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
134		146
135	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
136	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
137	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
138		150
139	=head1 WATCHERS	151	=head1 WATCHERS
140		152
141	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
142	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
…		…
147	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
148	is in control).	160	is in control).
149		161
150	Note that B<callbacks must not permanently change global variables>	162	Note that B<callbacks must not permanently change global variables>
151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152	callbacks must not C<die> >>. The former is good programming practise in	164	callbacks must not C<die> >>. The former is good programming practice in
153	Perl and the latter stems from the fact that exception handling differs	165	Perl and the latter stems from the fact that exception handling differs
154	widely between event loops.	166	widely between event loops.
155		167
156	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
157	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
158	to it).	170	to it).
159		171
160	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.
161		173
162	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
163	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.
164		176
165	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
166		178
167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
168	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
169	undef $w;	181	undef $w;
170	});	182	});
…		…
172	Note that C<my $w; $w => combination. This is necessary because in Perl,	184	Note that C<my $w; $w => combination. This is necessary because in Perl,
173	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
174	declared.	186	declared.
175		187
176	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
177		195
178	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
179	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
180		198
181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
…		…
196		214
197	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.
198	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
199	underlying file descriptor.	217	underlying file descriptor.
200		218
201	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
202	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
203	handles.	221	handles.
204		222
205	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
206	watcher.	224	watcher.
…		…
211	undef $w;	229	undef $w;
212	});	230	});
213		231
214	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
215		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
216	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 >>
217	method with the following mandatory arguments:	243	method with the following mandatory arguments:
218		244
219	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
220	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
…		…
222		248
223	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
224	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
225	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
226		252
227	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
228	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
229	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
230	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
231	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.
232		258
233	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
234	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
235	only approximate.	261	only approximate.
236		262
237	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
238		264
239	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
257		283
258	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
259	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
260	"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
261	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
262	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.
263		289
264	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
265	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
266	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)
267	timers.	293	timers.
268		294
269	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
270	AnyEvent API.	296	AnyEvent API.
…		…
292	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
293	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
294		320
295	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
296	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
297	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
298		324
299	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
300	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
301		327
302	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>
303	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
304		330
305	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
306	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
307	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
308	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
309	after three seconds.	335	after three seconds.
310		336
…		…
330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
331	account.	357	account.
332		358
333	=item AnyEvent->now_update	359	=item AnyEvent->now_update
334		360
335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache	361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
336	the current time for each loop iteration (see the discussion of L<<	362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
337	AnyEvent->now >>, above).	363	above).
338		364
339	When a callback runs for a long time (or when the process sleeps), then	365	When a callback runs for a long time (or when the process sleeps), then
340	this "current" time will differ substantially from the real time, which	366	this "current" time will differ substantially from the real time, which
341	might affect timers and time-outs.	367	might affect timers and time-outs.
342		368
343	When this is the case, you can call this method, which will update the	369	When this is the case, you can call this method, which will update the
344	event loop's idea of "current time".	370	event loop's idea of "current time".
345		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
346	Note that updating the time I<might> cause some events to be handled.	379	Note that updating the time I<might> cause some events to be handled.
347		380
348	=back	381	=back
349		382
350	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351		386
352	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
353	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
354	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
355		390
…		…
361	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
362	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,
363	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
364		399
365	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
366	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
367		403
368	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
369	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
370		407
371	Example: exit on SIGINT	408	Example: exit on SIGINT
372		409
373	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
374		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$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
375	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
376		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
377	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.
378		454
379	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,
380	watches for any child process exit). The watcher will triggered only when	456	using C<0> watches for any child process exit, on others this will
381	the child process has finished and an exit status is available, not on	457	croak). The watcher will be triggered only when the child process has
382	any trace events (stopped/continued).	458	finished and an exit status is available, not on any trace events
		459	(stopped/continued).
383		460
384	The callback will be called with the pid and exit status (as returned by	461	The callback will be called with the pid and exit status (as returned by
385	waitpid), so unlike other watcher types, you I<can> rely on child watcher	462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
386	callback arguments.	463	callback arguments.
387		464
…		…
403		480
404	This means you cannot create a child watcher as the very first	481	This means you cannot create a child watcher as the very first
405	thing in an AnyEvent program, you I<have> to create at least one	482	thing in an AnyEvent program, you I<have> to create at least one
406	watcher before you C<fork> the child (alternatively, you can call	483	watcher before you C<fork> the child (alternatively, you can call
407	C<AnyEvent::detect>).	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.
408		489
409	Example: fork a process and wait for it	490	Example: fork a process and wait for it
410		491
411	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
412		493
…		…
424	# do something else, then wait for process exit	505	# do something else, then wait for process exit
425	$done->recv;	506	$done->recv;
426		507
427	=head2 IDLE WATCHERS	508	=head2 IDLE WATCHERS
428		509
429	Sometimes there is a need to do something, but it is not so important	510	$w = AnyEvent->idle (cb => <callback>);
430	to do it instantly, but only when there is nothing better to do. This
431	"nothing better to do" is usually defined to be "no other events need
432	attention by the event loop".
433		511
434	Idle watchers ideally get invoked when the event loop has nothing	512	This will repeatedly invoke the callback after the process becomes idle,
435	better to do, just before it would block the process to wait for new	513	until either the watcher is destroyed or new events have been detected.
436	events. Instead of blocking, the idle watcher is invoked.
437		514
438	Most event loops unfortunately do not really support idle watchers (only	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
439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
440	will simply call the callback "from time to time".	526	will simply call the callback "from time to time".
441		527
442	Example: read lines from STDIN, but only process them when the	528	Example: read lines from STDIN, but only process them when the
443	program is otherwise idle:	529	program is otherwise idle:
…		…
459	});	545	});
460	});	546	});
461		547
462	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
463		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
		554
464	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
465	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
466	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
467		558
468	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
469	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).
470		561
471	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
472	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.
473		566
474	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
475	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
476
477	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
478	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
479	the results).	571	the results).
480		572
481	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
482	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
483	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<<
484	->send >> method).	576	->send >> method).
485		577
486	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
487	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:
488	in time where multiple outstanding events have been processed. And yet	580
489	another way to call them is transactions - each condition variable can be	581	=over 4
490	used to represent a transaction, which finishes at some point and delivers	582
491	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
492		601
493	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
494	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,
495	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
496	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
…		…
509		618
510	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
511	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
512	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
513	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
514	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
515		624
516	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
517	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
518	for the send to occur.	627	for the send to occur.
519		628
520	Example: wait for a timer.	629	Example: wait for a timer.
521		630
522	# wait till the result is ready	631	# condition: "wait till the timer is fired"
523	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
524		633
525	# do something such as adding a timer	634	# create the timer - we could wait for, say
526	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
527	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
528	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
529	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
530	after => 1,	639	after => 1,
531	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
532	);	641	);
533		642
534	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
535	# calls send	644	# calls ->send
536	$result_ready->recv;	645	$timer_fired->recv;
537		646
538	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
539	condition variables are also code references.	648	variables are also callable directly.
540		649
541	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
542	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
543	$done->recv;	652	$done->recv;
544		653
…		…
550		659
551	...	660	...
552		661
553	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
554		663
555	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
556	results are available:	665	results are available:
557		666
558	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
559	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
560	});	669	});
…		…
578	immediately from within send.	687	immediately from within send.
579		688
580	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
581	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
582		691
583	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
584	(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
585	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
586	overloading, so as tempting as it may be, passing a condition variable
587	instead of a callback does not work. Both the pure perl and EV loops
588	support overloading, however, as well as all functions that use perl to
589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
590	example).
591		695
592	=item $cv->croak ($error)	696	=item $cv->croak ($error)
593		697
594	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
595	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
596		700
597	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
598	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.
599		707
600	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
601		709
602	=item $cv->end	710	=item $cv->end
603		711
…		…
605	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
606	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
607		715
608	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
609	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
610	>>, 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
611	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
612	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.
613		722
614	You can think of C<< $cv->send >> giving you an OR condition (one call	723	You can think of C<< $cv->send >> giving you an OR condition (one call
615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND	724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).	725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617		726
…		…
639	one call to C<begin>, so the condvar waits for all calls to C<end> before	748	one call to C<begin>, so the condvar waits for all calls to C<end> before
640	sending.	749	sending.
641		750
642	The ping example mentioned above is slightly more complicated, as the	751	The ping example mentioned above is slightly more complicated, as the
643	there are results to be passwd back, and the number of tasks that are	752	there are results to be passwd back, and the number of tasks that are
644	begung can potentially be zero:	753	begun can potentially be zero:
645		754
646	my $cv = AnyEvent->condvar;	755	my $cv = AnyEvent->condvar;
647		756
648	my %result;	757	my %result;
649	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
650		759
651	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
652	$cv->begin;	761	$cv->begin;
653	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
654	$result{$host} = ...;	763	$result{$host} = ...;
…		…
670	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
671	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
672	doesn't execute once).	781	doesn't execute once).
673		782
674	This is the general pattern when you "fan out" into multiple (but	783	This is the general pattern when you "fan out" into multiple (but
675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
676	the callback and ensure C<end> is called at least once, and then, for each	785	the callback and ensure C<end> is called at least once, and then, for each
677	subrequest you start, call C<begin> and for each subrequest you finish,	786	subrequest you start, call C<begin> and for each subrequest you finish,
678	call C<end>.	787	call C<end>.
679		788
680	=back	789	=back
…		…
687	=over 4	796	=over 4
688		797
689	=item $cv->recv	798	=item $cv->recv
690		799
691	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
692	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
693	normally.	802	normally.
694		803
695	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
696	will return immediately.	805	will return immediately.
697		806
…		…
699	function will call C<croak>.	808	function will call C<croak>.
700		809
701	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,
702	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
703		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
704	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
705	(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
706	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
707	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
708	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
709	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,
710	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
711		827
712	Another reason I<never> to C<< ->recv >> in a module is that you cannot
713	sensibly have two C<< ->recv >>'s in parallel, as that would require
714	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
715	can supply.
716
717	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
718	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
719	versions and also integrates coroutines into AnyEvent, making blocking
720	C<< ->recv >> calls perfectly safe as long as they are done from another
721	coroutine (one that doesn't run the event loop).
722
723	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
724	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
725	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
726	waits otherwise.	831	waits otherwise.
727		832
728	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
734		839
735	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
736	replaces it before doing so.	841	replaces it before doing so.
737		842
738	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
739	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
740	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
741	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.
742		848
743	=back	849	=back
744		850
745	=head1 SUPPORTED EVENT LOOPS/BACKENDS	851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
746		852
…		…
749	=over 4	855	=over 4
750		856
751	=item Backends that are autoprobed when no other event loop can be found.	857	=item Backends that are autoprobed when no other event loop can be found.
752		858
753	EV is the preferred backend when no other event loop seems to be in	859	EV is the preferred backend when no other event loop seems to be in
754	use. If EV is not installed, then AnyEvent will try Event, and, failing	860	use. If EV is not installed, then AnyEvent will fall back to its own
755	that, will fall back to its own pure-perl implementation, which is	861	pure-perl implementation, which is available everywhere as it comes with
756	available everywhere as it comes with AnyEvent itself.	862	AnyEvent itself.
757		863
758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
761		866
762	=item Backends that are transparently being picked up when they are used.	867	=item Backends that are transparently being picked up when they are used.
763		868
764	These will be used when they are currently loaded when the first watcher	869	These will be used if they are already loaded when the first watcher
765	is created, in which case it is assumed that the application is using	870	is created, in which case it is assumed that the application is using
766	them. This means that AnyEvent will automatically pick the right backend	871	them. This means that AnyEvent will automatically pick the right backend
767	when the main program loads an event module before anything starts to	872	when the main program loads an event module before anything starts to
768	create watchers. Nothing special needs to be done by the main program.	873	create watchers. Nothing special needs to be done by the main program.
769		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
770	AnyEvent::Impl::Glib based on Glib, slow but very stable.	876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
771	AnyEvent::Impl::Tk based on Tk, very broken.	877	AnyEvent::Impl::Tk based on Tk, very broken.
772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
773	AnyEvent::Impl::POE based on POE, very slow, some limitations.	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).
774		884
775	=item Backends with special needs.	885	=item Backends with special needs.
776		886
777	Qt requires the Qt::Application to be instantiated first, but will	887	Qt requires the Qt::Application to be instantiated first, but will
778	otherwise be picked up automatically. As long as the main program	888	otherwise be picked up automatically. As long as the main program
779	instantiates the application before any AnyEvent watchers are created,	889	instantiates the application before any AnyEvent watchers are created,
780	everything should just work.	890	everything should just work.
781		891
782	AnyEvent::Impl::Qt based on Qt.	892	AnyEvent::Impl::Qt based on Qt.
783		893
784	Support for IO::Async can only be partial, as it is too broken and
785	architecturally limited to even support the AnyEvent API. It also
786	is the only event loop that needs the loop to be set explicitly, so
787	it can only be used by a main program knowing about AnyEvent. See
788	L<AnyEvent::Impl::Async> for the gory details.
789
790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
791
792	=item Event loops that are indirectly supported via other backends.	894	=item Event loops that are indirectly supported via other backends.
793		895
794	Some event loops can be supported via other modules:	896	Some event loops can be supported via other modules:
795		897
796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.	898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
…		…
821	Contains C<undef> until the first watcher is being created, before the	923	Contains C<undef> until the first watcher is being created, before the
822	backend has been autodetected.	924	backend has been autodetected.
823		925
824	Afterwards it contains the event model that is being used, which is the	926	Afterwards it contains the event model that is being used, which is the
825	name of the Perl class implementing the model. This class is usually one	927	name of the Perl class implementing the model. This class is usually one
826	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
827	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
828	will be C<urxvt::anyevent>).	930	will be C<urxvt::anyevent>).
829		931
830	=item AnyEvent::detect	932	=item AnyEvent::detect
831		933
832	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
833	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
834	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
835	runtime, and not e.g. while initialising of your module.	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).
836		942
837	If you need to do some initialisation before AnyEvent watchers are	943	If you need to do some initialisation before AnyEvent watchers are
838	created, use C<post_detect>.	944	created, use C<post_detect>.
839		945
840	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
841		947
842	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
843	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
844		950
845	The block will be executed I<after> the actual backend has been detected	951	The block will be executed I<after> the actual backend has been detected
846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been	952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do	953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
848	other initialisations - see the sources of L<AnyEvent::Strict> or	954	other initialisations - see the sources of L<AnyEvent::Strict> or
…		…
852	event module detection too early, for example, L<AnyEvent::AIO> creates	958	event module detection too early, for example, L<AnyEvent::AIO> creates
853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to	959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
854	avoid autodetecting the event module at load time.	960	avoid autodetecting the event module at load time.
855		961
856	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
857	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
858	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$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 ||= $guard;
859		982
860	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
861		984
862	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
863	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
864	the event loop has been chosen.	987	after the event loop has been chosen.
865		988
866	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
867	if it is defined then the event loop has already been detected, and the	990	if it is defined then the event loop has already been detected, and the
868	array will be ignored.	991	array will be ignored.
869		992
870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
871	it,as it takes care of these details.	994	it, as it takes care of these details.
872		995
873	This variable is mainly useful for modules that can do something useful	996	This variable is mainly useful for modules that can do something useful
874	when AnyEvent is used and thus want to know when it is initialised, but do	997	when AnyEvent is used and thus want to know when it is initialised, but do
875	not need to even load it by default. This array provides the means to hook	998	not need to even load it by default. This array provides the means to hook
876	into AnyEvent passively, without loading it.	999	into AnyEvent passively, without loading it.
877		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
878	=back	1054	=back
879		1055
880	=head1 WHAT TO DO IN A MODULE	1056	=head1 WHAT TO DO IN A MODULE
881		1057
882	As a module author, you should C<use AnyEvent> and call AnyEvent methods	1058	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
892	because it will stall the whole program, and the whole point of using	1068	because it will stall the whole program, and the whole point of using
893	events is to stay interactive.	1069	events is to stay interactive.
894		1070
895	It is fine, however, to call C<< ->recv >> when the user of your module	1071	It is fine, however, to call C<< ->recv >> when the user of your module
896	requests it (i.e. if you create a http request object ad have a method	1072	requests it (i.e. if you create a http request object ad have a method
897	called C<results> that returns the results, it should call C<< ->recv >>	1073	called C<results> that returns the results, it may call C<< ->recv >>
898	freely, as the user of your module knows what she is doing. always).	1074	freely, as the user of your module knows what she is doing. Always).
899		1075
900	=head1 WHAT TO DO IN THE MAIN PROGRAM	1076	=head1 WHAT TO DO IN THE MAIN PROGRAM
901		1077
902	There will always be a single main program - the only place that should	1078	There will always be a single main program - the only place that should
903	dictate which event model to use.	1079	dictate which event model to use.
904		1080
905	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1081	If the program is not event-based, it need not do anything special, even
906	do anything special (it does not need to be event-based) and let AnyEvent	1082	when it depends on a module that uses an AnyEvent. If the program itself
907	decide which implementation to chose if some module relies on it.	1083	uses AnyEvent, but does not care which event loop is used, all it needs
		1084	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1085	available loop implementation.
908		1086
909	If the main program relies on a specific event model - for example, in	1087	If the main program relies on a specific event model - for example, in
910	Gtk2 programs you have to rely on the Glib module - you should load the	1088	Gtk2 programs you have to rely on the Glib module - you should load the
911	event module before loading AnyEvent or any module that uses it: generally	1089	event module before loading AnyEvent or any module that uses it: generally
912	speaking, you should load it as early as possible. The reason is that	1090	speaking, you should load it as early as possible. The reason is that
913	modules might create watchers when they are loaded, and AnyEvent will	1091	modules might create watchers when they are loaded, and AnyEvent will
914	decide on the event model to use as soon as it creates watchers, and it	1092	decide on the event model to use as soon as it creates watchers, and it
915	might chose the wrong one unless you load the correct one yourself.	1093	might choose the wrong one unless you load the correct one yourself.
916		1094
917	You can chose to use a pure-perl implementation by loading the	1095	You can chose to use a pure-perl implementation by loading the
918	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1096	C<AnyEvent::Loop> module, which gives you similar behaviour
919	everywhere, but letting AnyEvent chose the model is generally better.	1097	everywhere, but letting AnyEvent chose the model is generally better.
920		1098
921	=head2 MAINLOOP EMULATION	1099	=head2 MAINLOOP EMULATION
922		1100
923	Sometimes (often for short test scripts, or even standalone programs who	1101	Sometimes (often for short test scripts, or even standalone programs who
…		…
938	=head1 OTHER MODULES	1116	=head1 OTHER MODULES
939		1117
940	The following is a non-exhaustive list of additional modules that use	1118	The following is a non-exhaustive list of additional modules that use
941	AnyEvent as a client and can therefore be mixed easily with other AnyEvent	1119	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
942	modules and other event loops in the same program. Some of the modules	1120	modules and other event loops in the same program. Some of the modules
943	come with AnyEvent, most are available via CPAN.	1121	come as part of AnyEvent, the others are available via CPAN.
944		1122
945	=over 4	1123	=over 4
946		1124
947	=item L<AnyEvent::Util>	1125	=item L<AnyEvent::Util>
948		1126
949	Contains various utility functions that replace often-used but blocking	1127	Contains various utility functions that replace often-used blocking
950	functions such as C<inet_aton> by event-/callback-based versions.	1128	functions such as C<inet_aton> with event/callback-based versions.
951		1129
952	=item L<AnyEvent::Socket>	1130	=item L<AnyEvent::Socket>
953		1131
954	Provides various utility functions for (internet protocol) sockets,	1132	Provides various utility functions for (internet protocol) sockets,
955	addresses and name resolution. Also functions to create non-blocking tcp	1133	addresses and name resolution. Also functions to create non-blocking tcp
…		…
957		1135
958	=item L<AnyEvent::Handle>	1136	=item L<AnyEvent::Handle>
959		1137
960	Provide read and write buffers, manages watchers for reads and writes,	1138	Provide read and write buffers, manages watchers for reads and writes,
961	supports raw and formatted I/O, I/O queued and fully transparent and	1139	supports raw and formatted I/O, I/O queued and fully transparent and
962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1140	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
963		1141
964	=item L<AnyEvent::DNS>	1142	=item L<AnyEvent::DNS>
965		1143
966	Provides rich asynchronous DNS resolver capabilities.	1144	Provides rich asynchronous DNS resolver capabilities.
967		1145
		1146	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1147
		1148	Implement event-based interfaces to the protocols of the same name (for
		1149	the curious, IGS is the International Go Server and FCP is the Freenet
		1150	Client Protocol).
		1151
		1152	=item L<AnyEvent::Handle::UDP>
		1153
		1154	Here be danger!
		1155
		1156	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1157	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1158	its use of a stream-based API with a protocol that isn't streamable, that
		1159	the only way to improve it is to delete it.
		1160
		1161	It features data corruption (but typically only under load) and general
		1162	confusion. On top, the author is not only clueless about UDP but also
		1163	fact-resistant - some gems of his understanding: "connect doesn't work
		1164	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1165	packets", "I don't need to implement proper error checking as UDP doesn't
		1166	support error checking" and so on - he doesn't even understand what's
		1167	wrong with his module when it is explained to him.
		1168
968	=item L<AnyEvent::HTTP>	1169	=item L<AnyEvent::DBI>
969		1170
970	A simple-to-use HTTP library that is capable of making a lot of concurrent	1171	Executes L<DBI> requests asynchronously in a proxy process for you,
971	HTTP requests.	1172	notifying you in an event-based way when the operation is finished.
		1173
		1174	=item L<AnyEvent::AIO>
		1175
		1176	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1177	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1178	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1179	file I/O, and much more.
972		1180
973	=item L<AnyEvent::HTTPD>	1181	=item L<AnyEvent::HTTPD>
974		1182
975	Provides a simple web application server framework.	1183	A simple embedded webserver.
976		1184
977	=item L<AnyEvent::FastPing>	1185	=item L<AnyEvent::FastPing>
978		1186
979	The fastest ping in the west.	1187	The fastest ping in the west.
980		1188
981	=item L<AnyEvent::DBI>
982
983	Executes L<DBI> requests asynchronously in a proxy process.
984
985	=item L<AnyEvent::AIO>
986
987	Truly asynchronous I/O, should be in the toolbox of every event
988	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
989	together.
990
991	=item L<AnyEvent::BDB>
992
993	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
994	L<BDB> and AnyEvent together.
995
996	=item L<AnyEvent::GPSD>
997
998	A non-blocking interface to gpsd, a daemon delivering GPS information.
999
1000	=item L<AnyEvent::IRC>
1001
1002	AnyEvent based IRC client module family (replacing the older Net::IRC3).
1003
1004	=item L<AnyEvent::XMPP>
1005
1006	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1007	Net::XMPP2>.
1008
1009	=item L<AnyEvent::IGS>
1010
1011	A non-blocking interface to the Internet Go Server protocol (used by
1012	L<App::IGS>).
1013
1014	=item L<Net::FCP>
1015
1016	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1017	of AnyEvent.
1018
1019	=item L<Event::ExecFlow>
1020
1021	High level API for event-based execution flow control.
1022
1023	=item L<Coro>	1189	=item L<Coro>
1024		1190
1025	Has special support for AnyEvent via L<Coro::AnyEvent>.	1191	Has special support for AnyEvent via L<Coro::AnyEvent>.
1026		1192
1027	=back	1193	=back
1028		1194
1029	=cut	1195	=cut
1030		1196
1031	package AnyEvent;	1197	package AnyEvent;
1032		1198
1033	no warnings;	1199	# basically a tuned-down version of common::sense
1034	use strict qw(vars subs);	1200	sub common_sense {
		1201	# from common:.sense 3.4
		1202	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1203	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1204	$^H |= 0x00000600;
		1205	}
1035		1206
		1207	BEGIN { AnyEvent::common_sense }
		1208
1036	use Carp;	1209	use Carp ();
1037		1210
1038	our $VERSION = 4.81;	1211	our $VERSION = '6.0';
1039	our $MODEL;	1212	our $MODEL;
1040		1213
1041	our $AUTOLOAD;
1042	our @ISA;	1214	our @ISA;
1043		1215
1044	our @REGISTRY;	1216	our @REGISTRY;
1045		1217
1046	our $WIN32;	1218	our $VERBOSE;
1047		1219
1048	BEGIN {	1220	BEGIN {
1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1221	require "AnyEvent/constants.pl";
		1222
1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1223	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1051		1224
1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1225	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1053	if ${^TAINT};	1226	if ${^TAINT};
1054	}
1055		1227
1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1228	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1229
		1230	}
		1231
		1232	our $MAX_SIGNAL_LATENCY = 10;
1057		1233
1058	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1234	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1059		1235
1060	{	1236	{
1061	my $idx;	1237	my $idx;
1062	$PROTOCOL{$_} = ++$idx	1238	$PROTOCOL{$_} = ++$idx
1063	for reverse split /\s*,\s*/,	1239	for reverse split /\s*,\s*/,
1064	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1240	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1065	}	1241	}
1066		1242
		1243	our @post_detect;
		1244
		1245	sub post_detect(&) {
		1246	my ($cb) = @_;
		1247
		1248	push @post_detect, $cb;
		1249
		1250	defined wantarray
		1251	? bless \$cb, "AnyEvent::Util::postdetect"
		1252	: ()
		1253	}
		1254
		1255	sub AnyEvent::Util::postdetect::DESTROY {
		1256	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1257	}
		1258
		1259	our $POSTPONE_W;
		1260	our @POSTPONE;
		1261
		1262	sub _postpone_exec {
		1263	undef $POSTPONE_W;
		1264
		1265	&{ shift @POSTPONE }
		1266	while @POSTPONE;
		1267	}
		1268
		1269	sub postpone(&) {
		1270	push @POSTPONE, shift;
		1271
		1272	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1273
		1274	()
		1275	}
		1276
1067	my @models = (	1277	our @models = (
1068	[EV:: => AnyEvent::Impl::EV::],	1278	[EV:: => AnyEvent::Impl::EV:: , 1],
1069	[Event:: => AnyEvent::Impl::Event::],	1279	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1071	# everything below here will not be autoprobed	1280	# everything below here will not (normally) be autoprobed
1072	# as the pureperl backend should work everywhere	1281	# as the pure perl backend should work everywhere
1073	# and is usually faster	1282	# and is usually faster
		1283	[Event:: => AnyEvent::Impl::Event::, 1],
1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1284	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1285	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1286	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1287	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1288	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1077	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1289	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1078	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1079	[Wx:: => AnyEvent::Impl::POE::],	1290	[Wx:: => AnyEvent::Impl::POE::],
1080	[Prima:: => AnyEvent::Impl::POE::],	1291	[Prima:: => AnyEvent::Impl::POE::],
1081	# IO::Async is just too broken - we would need workarounds for its	1292	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
1082	# byzantine signal and broken child handling, among others.	1293	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1083	# IO::Async is rather hard to detect, as it doesn't have any	1294	[FLTK:: => AnyEvent::Impl::FLTK2::],
1084	# obvious default class.
1085	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1086	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1087	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
1088	);	1295	);
1089		1296
1090	our %method = map +($_ => 1),	1297	# all autoloaded methods reserve the complete glob, not just the method slot.
		1298	# due to bugs in perls method cache implementation.
1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1299	our @methods = qw(io timer time now now_update signal child idle condvar);
1092		1300
1093	our @post_detect;
1094
1095	sub post_detect(&) {	1301	sub detect() {
1096	my ($cb) = @_;	1302	local $!; # for good measure
		1303	local $SIG{__DIE__}; # we use eval
1097		1304
1098	if ($MODEL) {	1305	# free some memory
1099	$cb->();	1306	*detect = sub () { $MODEL };
		1307	# undef &func doesn't correctly update the method cache. grmbl.
		1308	# so we delete the whole glob. grmbl.
		1309	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1310	# a glob with an active sub. hrm. i hope it works, but perl is
		1311	# usually buggy in this department. sigh.
		1312	delete @{"AnyEvent::"}{@methods};
		1313	undef @methods;
1100		1314
1101	1	1315	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1316	my $model = $1;
		1317	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1318	if (eval "require $model") {
		1319	$MODEL = $model;
		1320	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1102	} else {	1321	} else {
1103	push @post_detect, $cb;	1322	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1104		1323	}
1105	defined wantarray
1106	? bless \$cb, "AnyEvent::Util::postdetect"
1107	: ()
1108	}	1324	}
1109	}
1110		1325
1111	sub AnyEvent::Util::postdetect::DESTROY {	1326	# check for already loaded models
1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1113	}
1114
1115	sub detect() {
1116	unless ($MODEL) {	1327	unless ($MODEL) {
1117	no strict 'refs';	1328	for (@REGISTRY, @models) {
1118	local $SIG{__DIE__};	1329	my ($package, $model) = @$_;
1119		1330	if (${"$package\::VERSION"} > 0) {
1120	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1121	my $model = "AnyEvent::Impl::$1";
1122	if (eval "require $model") {	1331	if (eval "require $model") {
1123	$MODEL = $model;	1332	$MODEL = $model;
1124	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1333	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1125	} else {	1334	last;
1126	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1335	}
1127	}	1336	}
1128	}	1337	}
1129		1338
1130	# check for already loaded models
1131	unless ($MODEL) {	1339	unless ($MODEL) {
		1340	# try to autoload a model
1132	for (@REGISTRY, @models) {	1341	for (@REGISTRY, @models) {
1133	my ($package, $model) = @$_;	1342	my ($package, $model, $autoload) = @$_;
		1343	if (
		1344	$autoload
		1345	and eval "require $package"
1134	if (${"$package\::VERSION"} > 0) {	1346	and ${"$package\::VERSION"} > 0
1135	if (eval "require $model") {	1347	and eval "require $model"
		1348	) {
1136	$MODEL = $model;	1349	$MODEL = $model;
1137	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1350	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1138	last;	1351	last;
1139	}
1140	}	1352	}
1141	}	1353	}
1142		1354
1143	unless ($MODEL) {
1144	# try to load a model
1145
1146	for (@REGISTRY, @models) {
1147	my ($package, $model) = @$_;
1148	if (eval "require $package"
1149	and ${"$package\::VERSION"} > 0
1150	and eval "require $model") {
1151	$MODEL = $model;
1152	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1153	last;
1154	}
1155	}
1156
1157	$MODEL	1355	$MODEL
1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1356	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1159	}
1160	}	1357	}
1161
1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1163
1164	unshift @ISA, $MODEL;
1165
1166	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1167
1168	(shift @post_detect)->() while @post_detect;
1169	}	1358	}
1170		1359
		1360	# free memory only needed for probing
		1361	undef @models;
		1362	undef @REGISTRY;
		1363
		1364	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1365	unshift @ISA, $MODEL;
		1366
		1367	# now nuke some methods that are overridden by the backend.
		1368	# SUPER usage is not allowed in these.
		1369	for (qw(time signal child idle)) {
		1370	undef &{"AnyEvent::Base::$_"}
		1371	if defined &{"$MODEL\::$_"};
		1372	}
		1373
		1374	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1375	require AnyEvent::Strict;
		1376	}
		1377
		1378	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1379	require AnyEvent::Debug;
		1380	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1381	}
		1382
		1383	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1384	require AnyEvent::Socket;
		1385	require AnyEvent::Debug;
		1386
		1387	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1388	$shell =~ s/\$\$/$$/g;
		1389
		1390	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1391	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1392	}
		1393
		1394	(shift @post_detect)->() while @post_detect;
		1395	undef @post_detect;
		1396
		1397	*post_detect = sub(&) {
		1398	shift->();
		1399
		1400	undef
		1401	};
		1402
1171	$MODEL	1403	$MODEL
1172	}	1404	}
1173		1405
1174	sub AUTOLOAD {	1406	for my $name (@methods) {
1175	(my $func = $AUTOLOAD) =~ s/.*://;	1407	*$name = sub {
1176		1408	detect;
1177	$method{$func}	1409	# we use goto because
1178	or croak "$func: not a valid method for AnyEvent objects";	1410	# a) it makes the thunk more transparent
1179		1411	# b) it allows us to delete the thunk later
1180	detect unless $MODEL;	1412	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1181		1413	};
1182	my $class = shift;
1183	$class->$func (@_);
1184	}	1414	}
1185		1415
1186	# utility function to dup a filehandle. this is used by many backends	1416	# utility function to dup a filehandle. this is used by many backends
1187	# to support binding more than one watcher per filehandle (they usually	1417	# to support binding more than one watcher per filehandle (they usually
1188	# allow only one watcher per fd, so we dup it to get a different one).	1418	# allow only one watcher per fd, so we dup it to get a different one).
1189	sub _dupfh($$;$$) {	1419	sub _dupfh($$;$$) {
1190	my ($poll, $fh, $r, $w) = @_;	1420	my ($poll, $fh, $r, $w) = @_;
1191		1421
1192	# cygwin requires the fh mode to be matching, unix doesn't	1422	# cygwin requires the fh mode to be matching, unix doesn't
1193	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");	1423	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1194		1424
1195	open my $fh2, "$mode&", $fh	1425	open my $fh2, $mode, $fh
1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";	1426	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1197		1427
1198	# we assume CLOEXEC is already set by perl in all important cases	1428	# we assume CLOEXEC is already set by perl in all important cases
1199		1429
1200	($fh2, $rw)	1430	($fh2, $rw)
1201	}	1431	}
1202		1432
		1433	=head1 SIMPLIFIED AE API
		1434
		1435	Starting with version 5.0, AnyEvent officially supports a second, much
		1436	simpler, API that is designed to reduce the calling, typing and memory
		1437	overhead by using function call syntax and a fixed number of parameters.
		1438
		1439	See the L<AE> manpage for details.
		1440
		1441	=cut
		1442
		1443	package AE;
		1444
		1445	our $VERSION = $AnyEvent::VERSION;
		1446
		1447	sub _reset() {
		1448	eval q{
		1449	# fall back to the main API by default - backends and AnyEvent::Base
		1450	# implementations can overwrite these.
		1451
		1452	sub io($$$) {
		1453	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1454	}
		1455
		1456	sub timer($$$) {
		1457	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1458	}
		1459
		1460	sub signal($$) {
		1461	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1462	}
		1463
		1464	sub child($$) {
		1465	AnyEvent->child (pid => $_[0], cb => $_[1])
		1466	}
		1467
		1468	sub idle($) {
		1469	AnyEvent->idle (cb => $_[0]);
		1470	}
		1471
		1472	sub cv(;&) {
		1473	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1474	}
		1475
		1476	sub now() {
		1477	AnyEvent->now
		1478	}
		1479
		1480	sub now_update() {
		1481	AnyEvent->now_update
		1482	}
		1483
		1484	sub time() {
		1485	AnyEvent->time
		1486	}
		1487
		1488	*postpone = \&AnyEvent::postpone;
		1489	};
		1490	die if $@;
		1491	}
		1492
		1493	BEGIN { _reset }
		1494
1203	package AnyEvent::Base;	1495	package AnyEvent::Base;
1204		1496
1205	# default implementations for many methods	1497	# default implementations for many methods
1206		1498
1207	BEGIN {	1499	sub time {
		1500	eval q{ # poor man's autoloading {}
		1501	# probe for availability of Time::HiRes
1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1502	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1503	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1209	*_time = \&Time::HiRes::time;	1504	*AE::time = \&Time::HiRes::time;
1210	# if (eval "use POSIX (); (POSIX::times())...	1505	# if (eval "use POSIX (); (POSIX::times())...
1211	} else {	1506	} else {
		1507	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1212	*_time = sub { time }; # epic fail	1508	*AE::time = sub (){ time }; # epic fail
		1509	}
		1510
		1511	*time = sub { AE::time }; # different prototypes
		1512	};
		1513	die if $@;
		1514
		1515	&time
		1516	}
		1517
		1518	*now = \&time;
		1519
		1520	sub now_update { }
		1521
		1522	sub _poll {
		1523	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1524	}
		1525
		1526	# default implementation for ->condvar
		1527	# in fact, the default should not be overwritten
		1528
		1529	sub condvar {
		1530	eval q{ # poor man's autoloading {}
		1531	*condvar = sub {
		1532	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1533	};
		1534
		1535	*AE::cv = sub (;&) {
		1536	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1537	};
		1538	};
		1539	die if $@;
		1540
		1541	&condvar
		1542	}
		1543
		1544	# default implementation for ->signal
		1545
		1546	our $HAVE_ASYNC_INTERRUPT;
		1547
		1548	sub _have_async_interrupt() {
		1549	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1550	&& eval "use Async::Interrupt 1.02 (); 1")
		1551	unless defined $HAVE_ASYNC_INTERRUPT;
		1552
		1553	$HAVE_ASYNC_INTERRUPT
		1554	}
		1555
		1556	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1557	our (%SIG_ASY, %SIG_ASY_W);
		1558	our ($SIG_COUNT, $SIG_TW);
		1559
		1560	# install a dummy wakeup watcher to reduce signal catching latency
		1561	# used by Impls
		1562	sub _sig_add() {
		1563	unless ($SIG_COUNT++) {
		1564	# try to align timer on a full-second boundary, if possible
		1565	my $NOW = AE::now;
		1566
		1567	$SIG_TW = AE::timer
		1568	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1569	$MAX_SIGNAL_LATENCY,
		1570	sub { } # just for the PERL_ASYNC_CHECK
		1571	;
1213	}	1572	}
1214	}	1573	}
1215		1574
1216	sub time { _time }	1575	sub _sig_del {
1217	sub now { _time }	1576	undef $SIG_TW
1218	sub now_update { }	1577	unless --$SIG_COUNT;
1219
1220	# default implementation for ->condvar
1221
1222	sub condvar {
1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1224	}	1578	}
1225		1579
1226	# default implementation for ->signal	1580	our $_sig_name_init; $_sig_name_init = sub {
		1581	eval q{ # poor man's autoloading {}
		1582	undef $_sig_name_init;
1227		1583
1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1584	if (_have_async_interrupt) {
		1585	*sig2num = \&Async::Interrupt::sig2num;
		1586	*sig2name = \&Async::Interrupt::sig2name;
		1587	} else {
		1588	require Config;
1229		1589
1230	sub _signal_exec {	1590	my %signame2num;
1231	sysread $SIGPIPE_R, my $dummy, 4;	1591	@signame2num{ split ' ', $Config::Config{sig_name} }
		1592	= split ' ', $Config::Config{sig_num};
1232		1593
1233	while (%SIG_EV) {	1594	my @signum2name;
1234	for (keys %SIG_EV) {	1595	@signum2name[values %signame2num] = keys %signame2num;
1235	delete $SIG_EV{$_};	1596
1236	$_->() for values %{ $SIG_CB{$_} || {} };	1597	*sig2num = sub($) {
		1598	$_[0] > 0 ? shift : $signame2num{+shift}
		1599	};
		1600	*sig2name = sub ($) {
		1601	$_[0] > 0 ? $signum2name[+shift] : shift
		1602	};
1237	}	1603	}
1238	}	1604	};
1239	}	1605	die if $@;
		1606	};
		1607
		1608	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1609	sub sig2name($) { &$_sig_name_init; &sig2name }
1240		1610
1241	sub signal {	1611	sub signal {
1242	my (undef, %arg) = @_;	1612	eval q{ # poor man's autoloading {}
		1613	# probe for availability of Async::Interrupt
		1614	if (_have_async_interrupt) {
		1615	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1243		1616
1244	unless ($SIGPIPE_R) {	1617	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1245	require Fcntl;	1618	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1246		1619
1247	if (AnyEvent::WIN32) {
1248	require AnyEvent::Util;
1249
1250	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1251	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1252	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1253	} else {	1620	} else {
		1621	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1622
		1623	if (AnyEvent::WIN32) {
		1624	require AnyEvent::Util;
		1625
		1626	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1627	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1628	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1629	} else {
1254	pipe $SIGPIPE_R, $SIGPIPE_W;	1630	pipe $SIGPIPE_R, $SIGPIPE_W;
1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1631	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1632	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1257		1633
1258	# not strictly required, as $^F is normally 2, but let's make sure...	1634	# not strictly required, as $^F is normally 2, but let's make sure...
1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1635	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1636	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1637	}
		1638
		1639	$SIGPIPE_R
		1640	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1641
		1642	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1261	}	1643	}
1262		1644
1263	$SIGPIPE_R	1645	*signal = $HAVE_ASYNC_INTERRUPT
1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1646	? sub {
		1647	my (undef, %arg) = @_;
1265		1648
1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1649	# async::interrupt
1267	}
1268
1269	my $signal = uc $arg{signal}	1650	my $signal = sig2num $arg{signal};
1270	or Carp::croak "required option 'signal' is missing";
1271
1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1651	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1652
		1653	$SIG_ASY{$signal} ||= new Async::Interrupt
		1654	cb => sub { undef $SIG_EV{$signal} },
		1655	signal => $signal,
		1656	pipe => [$SIGPIPE_R->filenos],
		1657	pipe_autodrain => 0,
		1658	;
		1659
		1660	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1661	}
		1662	: sub {
		1663	my (undef, %arg) = @_;
		1664
		1665	# pure perl
		1666	my $signal = sig2name $arg{signal};
		1667	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1668
1273	$SIG{$signal} ||= sub {	1669	$SIG{$signal} ||= sub {
1274	local $!;	1670	local $!;
1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1671	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1276	undef $SIG_EV{$signal};	1672	undef $SIG_EV{$signal};
		1673	};
		1674
		1675	# can't do signal processing without introducing races in pure perl,
		1676	# so limit the signal latency.
		1677	_sig_add;
		1678
		1679	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1680	}
		1681	;
		1682
		1683	*AnyEvent::Base::signal::DESTROY = sub {
		1684	my ($signal, $cb) = @{$_[0]};
		1685
		1686	_sig_del;
		1687
		1688	delete $SIG_CB{$signal}{$cb};
		1689
		1690	$HAVE_ASYNC_INTERRUPT
		1691	? delete $SIG_ASY{$signal}
		1692	: # delete doesn't work with older perls - they then
		1693	# print weird messages, or just unconditionally exit
		1694	# instead of getting the default action.
		1695	undef $SIG{$signal}
		1696	unless keys %{ $SIG_CB{$signal} };
		1697	};
		1698
		1699	*_signal_exec = sub {
		1700	$HAVE_ASYNC_INTERRUPT
		1701	? $SIGPIPE_R->drain
		1702	: sysread $SIGPIPE_R, (my $dummy), 9;
		1703
		1704	while (%SIG_EV) {
		1705	for (keys %SIG_EV) {
		1706	delete $SIG_EV{$_};
		1707	&$_ for values %{ $SIG_CB{$_} || {} };
		1708	}
		1709	}
		1710	};
1277	};	1711	};
		1712	die if $@;
1278		1713
1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1714	&signal
1280	}
1281
1282	sub AnyEvent::Base::signal::DESTROY {
1283	my ($signal, $cb) = @{$_[0]};
1284
1285	delete $SIG_CB{$signal}{$cb};
1286
1287	# delete doesn't work with older perls - they then
1288	# print weird messages, or just unconditionally exit
1289	# instead of getting the default action.
1290	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1291	}	1715	}
1292		1716
1293	# default implementation for ->child	1717	# default implementation for ->child
1294		1718
1295	our %PID_CB;	1719	our %PID_CB;
1296	our $CHLD_W;	1720	our $CHLD_W;
1297	our $CHLD_DELAY_W;	1721	our $CHLD_DELAY_W;
1298	our $WNOHANG;
1299		1722
1300	sub _sigchld {	1723	# used by many Impl's
1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1724	sub _emit_childstatus($$) {
		1725	my (undef, $rpid, $rstatus) = @_;
		1726
		1727	$_->($rpid, $rstatus)
1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1728	for values %{ $PID_CB{$rpid} || {} },
1303	(values %{ $PID_CB{0} || {} });	1729	values %{ $PID_CB{0} || {} };
1304	}
1305	}	1730	}
1306		1731
1307	sub child {	1732	sub child {
		1733	eval q{ # poor man's autoloading {}
		1734	*_sigchld = sub {
		1735	my $pid;
		1736
		1737	AnyEvent->_emit_childstatus ($pid, $?)
		1738	while ($pid = waitpid -1, WNOHANG) > 0;
		1739	};
		1740
		1741	*child = sub {
1308	my (undef, %arg) = @_;	1742	my (undef, %arg) = @_;
1309		1743
1310	defined (my $pid = $arg{pid} + 0)	1744	my $pid = $arg{pid};
1311	or Carp::croak "required option 'pid' is missing";	1745	my $cb = $arg{cb};
1312		1746
1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1747	$PID_CB{$pid}{$cb+0} = $cb;
1314		1748
1315	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1316
1317	unless ($CHLD_W) {	1749	unless ($CHLD_W) {
1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1750	$CHLD_W = AE::signal CHLD => \&_sigchld;
1319	# child could be a zombie already, so make at least one round	1751	# child could be a zombie already, so make at least one round
1320	&_sigchld;	1752	&_sigchld;
1321	}	1753	}
1322		1754
1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1755	bless [$pid, $cb+0], "AnyEvent::Base::child"
1324	}	1756	};
1325		1757
1326	sub AnyEvent::Base::child::DESTROY {	1758	*AnyEvent::Base::child::DESTROY = sub {
1327	my ($pid, $cb) = @{$_[0]};	1759	my ($pid, $icb) = @{$_[0]};
1328		1760
1329	delete $PID_CB{$pid}{$cb};	1761	delete $PID_CB{$pid}{$icb};
1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1762	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1331		1763
1332	undef $CHLD_W unless keys %PID_CB;	1764	undef $CHLD_W unless keys %PID_CB;
		1765	};
		1766	};
		1767	die if $@;
		1768
		1769	&child
1333	}	1770	}
1334		1771
1335	# idle emulation is done by simply using a timer, regardless	1772	# idle emulation is done by simply using a timer, regardless
1336	# of whether the process is idle or not, and not letting	1773	# of whether the process is idle or not, and not letting
1337	# the callback use more than 50% of the time.	1774	# the callback use more than 50% of the time.
1338	sub idle {	1775	sub idle {
		1776	eval q{ # poor man's autoloading {}
		1777	*idle = sub {
1339	my (undef, %arg) = @_;	1778	my (undef, %arg) = @_;
1340		1779
1341	my ($cb, $w, $rcb) = $arg{cb};	1780	my ($cb, $w, $rcb) = $arg{cb};
1342		1781
1343	$rcb = sub {	1782	$rcb = sub {
1344	if ($cb) {	1783	if ($cb) {
1345	$w = _time;	1784	$w = AE::time;
1346	&$cb;	1785	&$cb;
1347	$w = _time - $w;	1786	$w = AE::time - $w;
1348		1787
1349	# never use more then 50% of the time for the idle watcher,	1788	# never use more then 50% of the time for the idle watcher,
1350	# within some limits	1789	# within some limits
1351	$w = 0.0001 if $w < 0.0001;	1790	$w = 0.0001 if $w < 0.0001;
1352	$w = 5 if $w > 5;	1791	$w = 5 if $w > 5;
1353		1792
1354	$w = AnyEvent->timer (after => $w, cb => $rcb);	1793	$w = AE::timer $w, 0, $rcb;
1355	} else {	1794	} else {
1356	# clean up...	1795	# clean up...
1357	undef $w;	1796	undef $w;
1358	undef $rcb;	1797	undef $rcb;
		1798	}
		1799	};
		1800
		1801	$w = AE::timer 0.05, 0, $rcb;
		1802
		1803	bless \\$cb, "AnyEvent::Base::idle"
1359	}	1804	};
		1805
		1806	*AnyEvent::Base::idle::DESTROY = sub {
		1807	undef $${$_[0]};
		1808	};
1360	};	1809	};
		1810	die if $@;
1361		1811
1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1812	&idle
1363
1364	bless \\$cb, "AnyEvent::Base::idle"
1365	}
1366
1367	sub AnyEvent::Base::idle::DESTROY {
1368	undef $${$_[0]};
1369	}	1813	}
1370		1814
1371	package AnyEvent::CondVar;	1815	package AnyEvent::CondVar;
1372		1816
1373	our @ISA = AnyEvent::CondVar::Base::;	1817	our @ISA = AnyEvent::CondVar::Base::;
1374		1818
		1819	# only to be used for subclassing
		1820	sub new {
		1821	my $class = shift;
		1822	bless AnyEvent->condvar (@_), $class
		1823	}
		1824
1375	package AnyEvent::CondVar::Base;	1825	package AnyEvent::CondVar::Base;
1376		1826
1377	use overload	1827	#use overload
1378	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1828	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1379	fallback => 1;	1829	# fallback => 1;
		1830
		1831	# save 300+ kilobytes by dirtily hardcoding overloading
		1832	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1833	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1834	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1835	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1836
		1837	our $WAITING;
1380		1838
1381	sub _send {	1839	sub _send {
1382	# nop	1840	# nop
		1841	}
		1842
		1843	sub _wait {
		1844	AnyEvent->_poll until $_[0]{_ae_sent};
1383	}	1845	}
1384		1846
1385	sub send {	1847	sub send {
1386	my $cv = shift;	1848	my $cv = shift;
1387	$cv->{_ae_sent} = [@_];	1849	$cv->{_ae_sent} = [@_];
…		…
1396		1858
1397	sub ready {	1859	sub ready {
1398	$_[0]{_ae_sent}	1860	$_[0]{_ae_sent}
1399	}	1861	}
1400		1862
1401	sub _wait {
1402	AnyEvent->one_event while !$_[0]{_ae_sent};
1403	}
1404
1405	sub recv {	1863	sub recv {
		1864	unless ($_[0]{_ae_sent}) {
		1865	$WAITING
		1866	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1867
		1868	local $WAITING = 1;
1406	$_[0]->_wait;	1869	$_[0]->_wait;
		1870	}
1407		1871
1408	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1872	$_[0]{_ae_croak}
1409	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1873	and Carp::croak $_[0]{_ae_croak};
		1874
		1875	wantarray
		1876	? @{ $_[0]{_ae_sent} }
		1877	: $_[0]{_ae_sent}[0]
1410	}	1878	}
1411		1879
1412	sub cb {	1880	sub cb {
1413	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1881	my $cv = shift;
		1882
		1883	@_
		1884	and $cv->{_ae_cb} = shift
		1885	and $cv->{_ae_sent}
		1886	and (delete $cv->{_ae_cb})->($cv);
		1887
1414	$_[0]{_ae_cb}	1888	$cv->{_ae_cb}
1415	}	1889	}
1416		1890
1417	sub begin {	1891	sub begin {
1418	++$_[0]{_ae_counter};	1892	++$_[0]{_ae_counter};
1419	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1893	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1424	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1898	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1425	}	1899	}
1426		1900
1427	# undocumented/compatibility with pre-3.4	1901	# undocumented/compatibility with pre-3.4
1428	*broadcast = \&send;	1902	*broadcast = \&send;
1429	*wait = \&_wait;	1903	*wait = \&recv;
1430		1904
1431	=head1 ERROR AND EXCEPTION HANDLING	1905	=head1 ERROR AND EXCEPTION HANDLING
1432		1906
1433	In general, AnyEvent does not do any error handling - it relies on the	1907	In general, AnyEvent does not do any error handling - it relies on the
1434	caller to do that if required. The L<AnyEvent::Strict> module (see also	1908	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1468	C<PERL_ANYEVENT_MODEL>.	1942	C<PERL_ANYEVENT_MODEL>.
1469		1943
1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1944	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1471	model it chooses.	1945	model it chooses.
1472		1946
		1947	When set to C<8> or higher, then AnyEvent will report extra information on
		1948	which optional modules it loads and how it implements certain features.
		1949
1473	=item C<PERL_ANYEVENT_STRICT>	1950	=item C<PERL_ANYEVENT_STRICT>
1474		1951
1475	AnyEvent does not do much argument checking by default, as thorough	1952	AnyEvent does not do much argument checking by default, as thorough
1476	argument checking is very costly. Setting this variable to a true value	1953	argument checking is very costly. Setting this variable to a true value
1477	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1954	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1478	check the arguments passed to most method calls. If it finds any problems,	1955	check the arguments passed to most method calls. If it finds any problems,
1479	it will croak.	1956	it will croak.
1480		1957
1481	In other words, enables "strict" mode.	1958	In other words, enables "strict" mode.
1482		1959
1483	Unlike C<use strict>, it is definitely recommended to keep it off in	1960	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1484	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1961	>>, it is definitely recommended to keep it off in production. Keeping
1485	developing programs can be very useful, however.	1962	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1963	can be very useful, however.
		1964
		1965	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1966
		1967	If this env variable is set, then its contents will be interpreted by
		1968	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		1969	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		1970	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		1971
		1972	This takes place when the first watcher is created.
		1973
		1974	For example, to bind a debug shell on a unix domain socket in
		1975	F<< /tmp/debug<pid>.sock >>, you could use this:
		1976
		1977	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug\$\$.sock perlprog
		1978
		1979	Note that creating sockets in F</tmp> is very unsafe on multiuser
		1980	systems.
		1981
		1982	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		1983
		1984	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		1985	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
1486		1986
1487	=item C<PERL_ANYEVENT_MODEL>	1987	=item C<PERL_ANYEVENT_MODEL>
1488		1988
1489	This can be used to specify the event model to be used by AnyEvent, before	1989	This can be used to specify the event model to be used by AnyEvent, before
1490	auto detection and -probing kicks in. It must be a string consisting	1990	auto detection and -probing kicks in.
1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1991
		1992	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		1993	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1492	and the resulting module name is loaded and if the load was successful,	1994	resulting module name is loaded and - if the load was successful - used as
1493	used as event model. If it fails to load AnyEvent will proceed with	1995	event model backend. If it fails to load then AnyEvent will proceed with
1494	auto detection and -probing.	1996	auto detection and -probing.
1495		1997
1496	This functionality might change in future versions.	1998	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		1999	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2000	the end of a string designates a module name and quotes it appropriately).
1497		2001
1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	2002	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1499	could start your program like this:	2003	could start your program like this:
1500		2004
1501	PERL_ANYEVENT_MODEL=Perl perl ...	2005	PERL_ANYEVENT_MODEL=Perl perl ...
1502		2006
1503	=item C<PERL_ANYEVENT_PROTOCOLS>	2007	=item C<PERL_ANYEVENT_PROTOCOLS>
…		…
1552		2056
1553	When neither C<ca_file> nor C<ca_path> was specified during	2057	When neither C<ca_file> nor C<ca_path> was specified during
1554	L<AnyEvent::TLS> context creation, and either of these environment	2058	L<AnyEvent::TLS> context creation, and either of these environment
1555	variables exist, they will be used to specify CA certificate locations	2059	variables exist, they will be used to specify CA certificate locations
1556	instead of a system-dependent default.	2060	instead of a system-dependent default.
		2061
		2062	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2063
		2064	When these are set to C<1>, then the respective modules are not
		2065	loaded. Mostly good for testing AnyEvent itself.
1557		2066
1558	=back	2067	=back
1559		2068
1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2069	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1561		2070
…		…
1619	warn "read: $input\n"; # output what has been read	2128	warn "read: $input\n"; # output what has been read
1620	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2129	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1621	},	2130	},
1622	);	2131	);
1623		2132
1624	my $time_watcher; # can only be used once
1625
1626	sub new_timer {
1627	$timer = AnyEvent->timer (after => 1, cb => sub {	2133	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1628	warn "timeout\n"; # print 'timeout' about every second	2134	warn "timeout\n"; # print 'timeout' at most every second
1629	&new_timer; # and restart the time
1630	});	2135	});
1631	}
1632
1633	new_timer; # create first timer
1634		2136
1635	$cv->recv; # wait until user enters /^q/i	2137	$cv->recv; # wait until user enters /^q/i
1636		2138
1637	=head1 REAL-WORLD EXAMPLE	2139	=head1 REAL-WORLD EXAMPLE
1638		2140
…		…
1711		2213
1712	The actual code goes further and collects all errors (C<die>s, exceptions)	2214	The actual code goes further and collects all errors (C<die>s, exceptions)
1713	that occurred during request processing. The C<result> method detects	2215	that occurred during request processing. The C<result> method detects
1714	whether an exception as thrown (it is stored inside the $txn object)	2216	whether an exception as thrown (it is stored inside the $txn object)
1715	and just throws the exception, which means connection errors and other	2217	and just throws the exception, which means connection errors and other
1716	problems get reported tot he code that tries to use the result, not in a	2218	problems get reported to the code that tries to use the result, not in a
1717	random callback.	2219	random callback.
1718		2220
1719	All of this enables the following usage styles:	2221	All of this enables the following usage styles:
1720		2222
1721	1. Blocking:	2223	1. Blocking:
…		…
1769	through AnyEvent. The benchmark creates a lot of timers (with a zero	2271	through AnyEvent. The benchmark creates a lot of timers (with a zero
1770	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2272	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1771	which it is), lets them fire exactly once and destroys them again.	2273	which it is), lets them fire exactly once and destroys them again.
1772		2274
1773	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2275	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1774	distribution.	2276	distribution. It uses the L<AE> interface, which makes a real difference
		2277	for the EV and Perl backends only.
1775		2278
1776	=head3 Explanation of the columns	2279	=head3 Explanation of the columns
1777		2280
1778	I<watcher> is the number of event watchers created/destroyed. Since	2281	I<watcher> is the number of event watchers created/destroyed. Since
1779	different event models feature vastly different performances, each event	2282	different event models feature vastly different performances, each event
…		…
1800	watcher.	2303	watcher.
1801		2304
1802	=head3 Results	2305	=head3 Results
1803		2306
1804	name watchers bytes create invoke destroy comment	2307	name watchers bytes create invoke destroy comment
1805	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2308	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1806	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2309	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1807	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2310	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1808	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2311	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1809	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2312	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1810	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2313	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1811	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	2314	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1812	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	2315	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1813	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2316	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1814	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2317	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1815	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2318	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1816	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2319	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1817		2320
1818	=head3 Discussion	2321	=head3 Discussion
1819		2322
1820	The benchmark does I<not> measure scalability of the event loop very	2323	The benchmark does I<not> measure scalability of the event loop very
1821	well. For example, a select-based event loop (such as the pure perl one)	2324	well. For example, a select-based event loop (such as the pure perl one)
…		…
1833	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2336	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1834	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2337	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1835	cycles with POE.	2338	cycles with POE.
1836		2339
1837	C<EV> is the sole leader regarding speed and memory use, which are both	2340	C<EV> is the sole leader regarding speed and memory use, which are both
1838	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2341	maximal/minimal, respectively. When using the L<AE> API there is zero
		2342	overhead (when going through the AnyEvent API create is about 5-6 times
		2343	slower, with other times being equal, so still uses far less memory than
1839	far less memory than any other event loop and is still faster than Event	2344	any other event loop and is still faster than Event natively).
1840	natively.
1841		2345
1842	The pure perl implementation is hit in a few sweet spots (both the	2346	The pure perl implementation is hit in a few sweet spots (both the
1843	constant timeout and the use of a single fd hit optimisations in the perl	2347	constant timeout and the use of a single fd hit optimisations in the perl
1844	interpreter and the backend itself). Nevertheless this shows that it	2348	interpreter and the backend itself). Nevertheless this shows that it
1845	adds very little overhead in itself. Like any select-based backend its	2349	adds very little overhead in itself. Like any select-based backend its
…		…
1919	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2423	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1920	(1%) are active. This mirrors the activity of large servers with many	2424	(1%) are active. This mirrors the activity of large servers with many
1921	connections, most of which are idle at any one point in time.	2425	connections, most of which are idle at any one point in time.
1922		2426
1923	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2427	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1924	distribution.	2428	distribution. It uses the L<AE> interface, which makes a real difference
		2429	for the EV and Perl backends only.
1925		2430
1926	=head3 Explanation of the columns	2431	=head3 Explanation of the columns
1927		2432
1928	I<sockets> is the number of sockets, and twice the number of "servers" (as	2433	I<sockets> is the number of sockets, and twice the number of "servers" (as
1929	each server has a read and write socket end).	2434	each server has a read and write socket end).
…		…
1937	a new one that moves the timeout into the future.	2442	a new one that moves the timeout into the future.
1938		2443
1939	=head3 Results	2444	=head3 Results
1940		2445
1941	name sockets create request	2446	name sockets create request
1942	EV 20000 69.01 11.16	2447	EV 20000 62.66 7.99
1943	Perl 20000 73.32 35.87	2448	Perl 20000 68.32 32.64
1944	IOAsync 20000 157.00 98.14 epoll	2449	IOAsync 20000 174.06 101.15 epoll
1945	IOAsync 20000 159.31 616.06 poll	2450	IOAsync 20000 174.67 610.84 poll
1946	Event 20000 212.62 257.32	2451	Event 20000 202.69 242.91
1947	Glib 20000 651.16 1896.30	2452	Glib 20000 557.01 1689.52
1948	POE 20000 349.67 12317.24 uses POE::Loop::Event	2453	POE 20000 341.54 12086.32 uses POE::Loop::Event
1949		2454
1950	=head3 Discussion	2455	=head3 Discussion
1951		2456
1952	This benchmark I<does> measure scalability and overall performance of the	2457	This benchmark I<does> measure scalability and overall performance of the
1953	particular event loop.	2458	particular event loop.
…		…
2079	As you can see, the AnyEvent + EV combination even beats the	2584	As you can see, the AnyEvent + EV combination even beats the
2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2585	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2081	backend easily beats IO::Lambda and POE.	2586	backend easily beats IO::Lambda and POE.
2082		2587
2083	And even the 100% non-blocking version written using the high-level (and	2588	And even the 100% non-blocking version written using the high-level (and
2084	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a	2589	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2085	large margin, even though it does all of DNS, tcp-connect and socket I/O	2590	higher level ("unoptimised") abstractions by a large margin, even though
2086	in a non-blocking way.	2591	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2087		2592
2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2593	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2089	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are	2594	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2090	part of the IO::lambda distribution and were used without any changes.	2595	part of the IO::Lambda distribution and were used without any changes.
2091		2596
2092		2597
2093	=head1 SIGNALS	2598	=head1 SIGNALS
2094		2599
2095	AnyEvent currently installs handlers for these signals:	2600	AnyEvent currently installs handlers for these signals:
…		…
2100		2605
2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2606	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
2102	emulation for event loops that do not support them natively. Also, some	2607	emulation for event loops that do not support them natively. Also, some
2103	event loops install a similar handler.	2608	event loops install a similar handler.
2104		2609
2105	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will	2610	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2106	reset it to default, to avoid losing child exit statuses.	2611	AnyEvent will reset it to default, to avoid losing child exit statuses.
2107		2612
2108	=item SIGPIPE	2613	=item SIGPIPE
2109		2614
2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2615	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2111	when AnyEvent gets loaded.	2616	when AnyEvent gets loaded.
…		…
2129	if $SIG{CHLD} eq 'IGNORE';	2634	if $SIG{CHLD} eq 'IGNORE';
2130		2635
2131	$SIG{PIPE} = sub { }	2636	$SIG{PIPE} = sub { }
2132	unless defined $SIG{PIPE};	2637	unless defined $SIG{PIPE};
2133		2638
		2639	=head1 RECOMMENDED/OPTIONAL MODULES
		2640
		2641	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2642	its built-in modules) are required to use it.
		2643
		2644	That does not mean that AnyEvent won't take advantage of some additional
		2645	modules if they are installed.
		2646
		2647	This section explains which additional modules will be used, and how they
		2648	affect AnyEvent's operation.
		2649
		2650	=over 4
		2651
		2652	=item L<Async::Interrupt>
		2653
		2654	This slightly arcane module is used to implement fast signal handling: To
		2655	my knowledge, there is no way to do completely race-free and quick
		2656	signal handling in pure perl. To ensure that signals still get
		2657	delivered, AnyEvent will start an interval timer to wake up perl (and
		2658	catch the signals) with some delay (default is 10 seconds, look for
		2659	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2660
		2661	If this module is available, then it will be used to implement signal
		2662	catching, which means that signals will not be delayed, and the event loop
		2663	will not be interrupted regularly, which is more efficient (and good for
		2664	battery life on laptops).
		2665
		2666	This affects not just the pure-perl event loop, but also other event loops
		2667	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2668
		2669	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2670	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2671	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2672	does nothing for those backends.
		2673
		2674	=item L<EV>
		2675
		2676	This module isn't really "optional", as it is simply one of the backend
		2677	event loops that AnyEvent can use. However, it is simply the best event
		2678	loop available in terms of features, speed and stability: It supports
		2679	the AnyEvent API optimally, implements all the watcher types in XS, does
		2680	automatic timer adjustments even when no monotonic clock is available,
		2681	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2682	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2683	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2684
		2685	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2686	then this module will do nothing for you.
		2687
		2688	=item L<Guard>
		2689
		2690	The guard module, when used, will be used to implement
		2691	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2692	lot less memory), but otherwise doesn't affect guard operation much. It is
		2693	purely used for performance.
		2694
		2695	=item L<JSON> and L<JSON::XS>
		2696
		2697	One of these modules is required when you want to read or write JSON data
		2698	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2699	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2700
		2701	=item L<Net::SSLeay>
		2702
		2703	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2704	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2705	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2706
		2707	=item L<Time::HiRes>
		2708
		2709	This module is part of perl since release 5.008. It will be used when the
		2710	chosen event library does not come with a timing source of its own. The
		2711	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2712	try to use a monotonic clock for timing stability.
		2713
		2714	=back
		2715
		2716
2134	=head1 FORK	2717	=head1 FORK
2135		2718
2136	Most event libraries are not fork-safe. The ones who are usually are	2719	Most event libraries are not fork-safe. The ones who are usually are
2137	because they rely on inefficient but fork-safe C<select> or C<poll>	2720	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2138	calls. Only L<EV> is fully fork-aware.	2721	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2722	are usually badly thought-out hacks that are incompatible with fork in
		2723	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2724	continue event-processing in both parent and child (or both, if you know
		2725	what you are doing).
		2726
		2727	This means that, in general, you cannot fork and do event processing in
		2728	the child if the event library was initialised before the fork (which
		2729	usually happens when the first AnyEvent watcher is created, or the library
		2730	is loaded).
2139		2731
2140	If you have to fork, you must either do so I<before> creating your first	2732	If you have to fork, you must either do so I<before> creating your first
2141	watcher OR you must not use AnyEvent at all in the child.	2733	watcher OR you must not use AnyEvent at all in the child OR you must do
		2734	something completely out of the scope of AnyEvent.
		2735
		2736	The problem of doing event processing in the parent I<and> the child
		2737	is much more complicated: even for backends that I<are> fork-aware or
		2738	fork-safe, their behaviour is not usually what you want: fork clones all
		2739	watchers, that means all timers, I/O watchers etc. are active in both
		2740	parent and child, which is almost never what you want. USing C<exec>
		2741	to start worker children from some kind of manage rprocess is usually
		2742	preferred, because it is much easier and cleaner, at the expense of having
		2743	to have another binary.
2142		2744
2143		2745
2144	=head1 SECURITY CONSIDERATIONS	2746	=head1 SECURITY CONSIDERATIONS
2145		2747
2146	AnyEvent can be forced to load any event model via	2748	AnyEvent can be forced to load any event model via
…		…
2176	pronounced).	2778	pronounced).
2177		2779
2178		2780
2179	=head1 SEE ALSO	2781	=head1 SEE ALSO
2180		2782
		2783	Tutorial/Introduction: L<AnyEvent::Intro>.
		2784
		2785	FAQ: L<AnyEvent::FAQ>.
		2786
2181	Utility functions: L<AnyEvent::Util>.	2787	Utility functions: L<AnyEvent::Util>.
2182		2788
2183	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2789	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2184	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2790	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2185		2791
2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2792	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2793	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2794	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.	2795	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2190		2796
2191	Non-blocking file handles, sockets, TCP clients and	2797	Non-blocking file handles, sockets, TCP clients and
2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.	2798	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2193		2799
2194	Asynchronous DNS: L<AnyEvent::DNS>.	2800	Asynchronous DNS: L<AnyEvent::DNS>.
2195		2801
2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,	2802	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2197	L<Coro::Event>,
2198		2803
2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,	2804	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2200	L<AnyEvent::HTTP>.	2805	L<AnyEvent::HTTP>.
2201		2806
2202		2807
2203	=head1 AUTHOR	2808	=head1 AUTHOR
2204		2809

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