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Revision 1.357 by root, Sat Aug 13 02:20:29 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.
836		938
837	If you need to do some initialisation before AnyEvent watchers are	939	If you need to do some initialisation before AnyEvent watchers are
838	created, use C<post_detect>.	940	created, use C<post_detect>.
839		941
840	=item $guard = AnyEvent::post_detect { BLOCK }	942	=item $guard = AnyEvent::post_detect { BLOCK }
841		943
842	Arranges for the code block to be executed as soon as the event model is	944	Arranges for the code block to be executed as soon as the event model is
843	autodetected (or immediately if this has already happened).	945	autodetected (or immediately if that has already happened).
844		946
845	The block will be executed I<after> the actual backend has been detected	947	The block will be executed I<after> the actual backend has been detected
846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been	948	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do	949	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
848	other initialisations - see the sources of L<AnyEvent::Strict> or	950	other initialisations - see the sources of L<AnyEvent::Strict> or
…		…
852	event module detection too early, for example, L<AnyEvent::AIO> creates	954	event module detection too early, for example, L<AnyEvent::AIO> creates
853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to	955	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
854	avoid autodetecting the event module at load time.	956	avoid autodetecting the event module at load time.
855		957
856	If called in scalar or list context, then it creates and returns an object	958	If called in scalar or list context, then it creates and returns an object
857	that automatically removes the callback again when it is destroyed. See	959	that automatically removes the callback again when it is destroyed (or
		960	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
858	L<Coro::BDB> for a case where this is useful.	961	a case where this is useful.
		962
		963	Example: Create a watcher for the IO::AIO module and store it in
		964	C<$WATCHER>, but do so only do so after the event loop is initialised.
		965
		966	our WATCHER;
		967
		968	my $guard = AnyEvent::post_detect {
		969	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		970	};
		971
		972	# the ||= is important in case post_detect immediately runs the block,
		973	# as to not clobber the newly-created watcher. assigning both watcher and
		974	# post_detect guard to the same variable has the advantage of users being
		975	# able to just C<undef $WATCHER> if the watcher causes them grief.
		976
		977	$WATCHER ||= $guard;
859		978
860	=item @AnyEvent::post_detect	979	=item @AnyEvent::post_detect
861		980
862	If there are any code references in this array (you can C<push> to it	981	If there are any code references in this array (you can C<push> to it
863	before or after loading AnyEvent), then they will called directly after	982	before or after loading AnyEvent), then they will be called directly
864	the event loop has been chosen.	983	after the event loop has been chosen.
865		984
866	You should check C<$AnyEvent::MODEL> before adding to this array, though:	985	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	986	if it is defined then the event loop has already been detected, and the
868	array will be ignored.	987	array will be ignored.
869		988
870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows	989	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
871	it,as it takes care of these details.	990	it, as it takes care of these details.
872		991
873	This variable is mainly useful for modules that can do something useful	992	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	993	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	994	not need to even load it by default. This array provides the means to hook
876	into AnyEvent passively, without loading it.	995	into AnyEvent passively, without loading it.
877		996
		997	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		998	together, you could put this into Coro (this is the actual code used by
		999	Coro to accomplish this):
		1000
		1001	if (defined $AnyEvent::MODEL) {
		1002	# AnyEvent already initialised, so load Coro::AnyEvent
		1003	require Coro::AnyEvent;
		1004	} else {
		1005	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1006	# as soon as it is
		1007	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1008	}
		1009
		1010	=item AnyEvent::postpone { BLOCK }
		1011
		1012	Arranges for the block to be executed as soon as possible, but not before
		1013	the call itself returns. In practise, the block will be executed just
		1014	before the event loop polls for new events, or shortly afterwards.
		1015
		1016	This function never returns anything (to make the C<return postpone { ...
		1017	}> idiom more useful.
		1018
		1019	To understand the usefulness of this function, consider a function that
		1020	asynchronously does something for you and returns some transaction
		1021	object or guard to let you cancel the operation. For example,
		1022	C<AnyEvent::Socket::tcp_connect>:
		1023
		1024	# start a conenction attempt unless one is active
		1025	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1026	delete $self->{connect_guard};
		1027	...
		1028	};
		1029
		1030	Imagine that this function could instantly call the callback, for
		1031	example, because it detects an obvious error such as a negative port
		1032	number. Invoking the callback before the function returns causes problems
		1033	however: the callback will be called and will try to delete the guard
		1034	object. But since the function hasn't returned yet, there is nothing to
		1035	delete. When the function eventually returns it will assign the guard
		1036	object to C<< $self->{connect_guard} >>, where it will likely never be
		1037	deleted, so the program thinks it is still trying to connect.
		1038
		1039	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1040	callback directly on error:
		1041
		1042	$cb->(undef), return # signal error to callback, BAD!
		1043	if $some_error_condition;
		1044
		1045	It should use C<postpone>:
		1046
		1047	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1048	if $some_error_condition;
		1049
878	=back	1050	=back
879		1051
880	=head1 WHAT TO DO IN A MODULE	1052	=head1 WHAT TO DO IN A MODULE
881		1053
882	As a module author, you should C<use AnyEvent> and call AnyEvent methods	1054	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	1064	because it will stall the whole program, and the whole point of using
893	events is to stay interactive.	1065	events is to stay interactive.
894		1066
895	It is fine, however, to call C<< ->recv >> when the user of your module	1067	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	1068	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 >>	1069	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).	1070	freely, as the user of your module knows what she is doing. Always).
899		1071
900	=head1 WHAT TO DO IN THE MAIN PROGRAM	1072	=head1 WHAT TO DO IN THE MAIN PROGRAM
901		1073
902	There will always be a single main program - the only place that should	1074	There will always be a single main program - the only place that should
903	dictate which event model to use.	1075	dictate which event model to use.
904		1076
905	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1077	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	1078	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.	1079	uses AnyEvent, but does not care which event loop is used, all it needs
		1080	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1081	available loop implementation.
908		1082
909	If the main program relies on a specific event model - for example, in	1083	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	1084	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	1085	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	1086	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	1087	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	1088	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.	1089	might choose the wrong one unless you load the correct one yourself.
916		1090
917	You can chose to use a pure-perl implementation by loading the	1091	You can chose to use a pure-perl implementation by loading the
918	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1092	C<AnyEvent::Loop> module, which gives you similar behaviour
919	everywhere, but letting AnyEvent chose the model is generally better.	1093	everywhere, but letting AnyEvent chose the model is generally better.
920		1094
921	=head2 MAINLOOP EMULATION	1095	=head2 MAINLOOP EMULATION
922		1096
923	Sometimes (often for short test scripts, or even standalone programs who	1097	Sometimes (often for short test scripts, or even standalone programs who
…		…
938	=head1 OTHER MODULES	1112	=head1 OTHER MODULES
939		1113
940	The following is a non-exhaustive list of additional modules that use	1114	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	1115	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	1116	modules and other event loops in the same program. Some of the modules
943	come with AnyEvent, most are available via CPAN.	1117	come as part of AnyEvent, the others are available via CPAN.
944		1118
945	=over 4	1119	=over 4
946		1120
947	=item L<AnyEvent::Util>	1121	=item L<AnyEvent::Util>
948		1122
949	Contains various utility functions that replace often-used but blocking	1123	Contains various utility functions that replace often-used blocking
950	functions such as C<inet_aton> by event-/callback-based versions.	1124	functions such as C<inet_aton> with event/callback-based versions.
951		1125
952	=item L<AnyEvent::Socket>	1126	=item L<AnyEvent::Socket>
953		1127
954	Provides various utility functions for (internet protocol) sockets,	1128	Provides various utility functions for (internet protocol) sockets,
955	addresses and name resolution. Also functions to create non-blocking tcp	1129	addresses and name resolution. Also functions to create non-blocking tcp
…		…
957		1131
958	=item L<AnyEvent::Handle>	1132	=item L<AnyEvent::Handle>
959		1133
960	Provide read and write buffers, manages watchers for reads and writes,	1134	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	1135	supports raw and formatted I/O, I/O queued and fully transparent and
962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1136	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
963		1137
964	=item L<AnyEvent::DNS>	1138	=item L<AnyEvent::DNS>
965		1139
966	Provides rich asynchronous DNS resolver capabilities.	1140	Provides rich asynchronous DNS resolver capabilities.
967		1141
		1142	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1143
		1144	Implement event-based interfaces to the protocols of the same name (for
		1145	the curious, IGS is the International Go Server and FCP is the Freenet
		1146	Client Protocol).
		1147
		1148	=item L<AnyEvent::Handle::UDP>
		1149
		1150	Here be danger!
		1151
		1152	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1153	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1154	its use of a stream-based API with a protocol that isn't streamable, that
		1155	the only way to improve it is to delete it.
		1156
		1157	It features data corruption (but typically only under load) and general
		1158	confusion. On top, the author is not only clueless about UDP but also
		1159	fact-resistant - some gems of his understanding: "connect doesn't work
		1160	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1161	packets", "I don't need to implement proper error checking as UDP doesn't
		1162	support error checking" and so on - he doesn't even understand what's
		1163	wrong with his module when it is explained to him.
		1164
968	=item L<AnyEvent::HTTP>	1165	=item L<AnyEvent::DBI>
969		1166
970	A simple-to-use HTTP library that is capable of making a lot of concurrent	1167	Executes L<DBI> requests asynchronously in a proxy process for you,
971	HTTP requests.	1168	notifying you in an event-based way when the operation is finished.
		1169
		1170	=item L<AnyEvent::AIO>
		1171
		1172	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1173	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1174	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1175	file I/O, and much more.
972		1176
973	=item L<AnyEvent::HTTPD>	1177	=item L<AnyEvent::HTTPD>
974		1178
975	Provides a simple web application server framework.	1179	A simple embedded webserver.
976		1180
977	=item L<AnyEvent::FastPing>	1181	=item L<AnyEvent::FastPing>
978		1182
979	The fastest ping in the west.	1183	The fastest ping in the west.
980		1184
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>	1185	=item L<Coro>
1024		1186
1025	Has special support for AnyEvent via L<Coro::AnyEvent>.	1187	Has special support for AnyEvent via L<Coro::AnyEvent>.
1026		1188
1027	=back	1189	=back
1028		1190
1029	=cut	1191	=cut
1030		1192
1031	package AnyEvent;	1193	package AnyEvent;
1032		1194
1033	no warnings;	1195	# basically a tuned-down version of common::sense
1034	use strict qw(vars subs);	1196	sub common_sense {
		1197	# from common:.sense 3.4
		1198	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1199	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1200	$^H |= 0x00000600;
		1201	}
1035		1202
		1203	BEGIN { AnyEvent::common_sense }
		1204
1036	use Carp;	1205	use Carp ();
1037		1206
1038	our $VERSION = 4.801;	1207	our $VERSION = '5.34';
1039	our $MODEL;	1208	our $MODEL;
1040		1209
1041	our $AUTOLOAD;
1042	our @ISA;	1210	our @ISA;
1043		1211
1044	our @REGISTRY;	1212	our @REGISTRY;
1045		1213
1046	our $WIN32;	1214	our $VERBOSE;
1047		1215
1048	BEGIN {	1216	BEGIN {
1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1217	require "AnyEvent/constants.pl";
		1218
1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1219	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1051		1220
1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1221	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1053	if ${^TAINT};	1222	if ${^TAINT};
1054	}
1055		1223
1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1224	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1225
		1226	}
		1227
		1228	our $MAX_SIGNAL_LATENCY = 10;
1057		1229
1058	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1230	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1059		1231
1060	{	1232	{
1061	my $idx;	1233	my $idx;
1062	$PROTOCOL{$_} = ++$idx	1234	$PROTOCOL{$_} = ++$idx
1063	for reverse split /\s*,\s*/,	1235	for reverse split /\s*,\s*/,
1064	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1236	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1065	}	1237	}
1066		1238
		1239	our @post_detect;
		1240
		1241	sub post_detect(&) {
		1242	my ($cb) = @_;
		1243
		1244	push @post_detect, $cb;
		1245
		1246	defined wantarray
		1247	? bless \$cb, "AnyEvent::Util::postdetect"
		1248	: ()
		1249	}
		1250
		1251	sub AnyEvent::Util::postdetect::DESTROY {
		1252	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1253	}
		1254
		1255	our $POSTPONE_W;
		1256	our @POSTPONE;
		1257
		1258	sub _postpone_exec {
		1259	undef $POSTPONE_W;
		1260
		1261	&{ shift @POSTPONE }
		1262	while @POSTPONE;
		1263	}
		1264
		1265	sub postpone(&) {
		1266	push @POSTPONE, shift;
		1267
		1268	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1269
		1270	()
		1271	}
		1272
1067	my @models = (	1273	our @models = (
1068	[EV:: => AnyEvent::Impl::EV::],	1274	[EV:: => AnyEvent::Impl::EV:: , 1],
1069	[Event:: => AnyEvent::Impl::Event::],	1275	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1071	# everything below here will not be autoprobed	1276	# everything below here will not (normally) be autoprobed
1072	# as the pureperl backend should work everywhere	1277	# as the pure perl backend should work everywhere
1073	# and is usually faster	1278	# and is usually faster
		1279	[Event:: => AnyEvent::Impl::Event::, 1],
1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1280	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1281	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1282	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1283	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1284	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1077	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1285	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1078	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1079	[Wx:: => AnyEvent::Impl::POE::],	1286	[Wx:: => AnyEvent::Impl::POE::],
1080	[Prima:: => AnyEvent::Impl::POE::],	1287	[Prima:: => AnyEvent::Impl::POE::],
1081	# IO::Async is just too broken - we would need workarounds for its	1288	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
1082	# byzantine signal and broken child handling, among others.	1289	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1083	# IO::Async is rather hard to detect, as it doesn't have any	1290	[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	);	1291	);
1089		1292
1090	our %method = map +($_ => 1),	1293	# all autoloaded methods reserve the complete glob, not just the method slot.
		1294	# due to bugs in perls method cache implementation.
1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1295	our @methods = qw(io timer time now now_update signal child idle condvar);
1092		1296
1093	our @post_detect;
1094
1095	sub post_detect(&) {	1297	sub detect() {
1096	my ($cb) = @_;	1298	local $!; # for good measure
		1299	local $SIG{__DIE__}; # we use eval
1097		1300
1098	if ($MODEL) {	1301	# free some memory
1099	$cb->();	1302	*detect = sub () { $MODEL };
		1303	# undef &func doesn't correctly update the method cache. grmbl.
		1304	# so we delete the whole glob. grmbl.
		1305	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1306	# a glob with an active sub. hrm. i hope it works, but perl is
		1307	# usually buggy in this department. sigh.
		1308	delete @{"AnyEvent::"}{@methods};
		1309	undef @methods;
1100		1310
1101	1	1311	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1312	my $model = $1;
		1313	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1314	if (eval "require $model") {
		1315	$MODEL = $model;
		1316	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1102	} else {	1317	} else {
1103	push @post_detect, $cb;	1318	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1104		1319	}
1105	defined wantarray
1106	? bless \$cb, "AnyEvent::Util::postdetect"
1107	: ()
1108	}	1320	}
1109	}
1110		1321
1111	sub AnyEvent::Util::postdetect::DESTROY {	1322	# check for already loaded models
1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1113	}
1114
1115	sub detect() {
1116	unless ($MODEL) {	1323	unless ($MODEL) {
1117	no strict 'refs';	1324	for (@REGISTRY, @models) {
1118	local $SIG{__DIE__};	1325	my ($package, $model) = @$_;
1119		1326	if (${"$package\::VERSION"} > 0) {
1120	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1121	my $model = "AnyEvent::Impl::$1";
1122	if (eval "require $model") {	1327	if (eval "require $model") {
1123	$MODEL = $model;	1328	$MODEL = $model;
1124	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1329	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1125	} else {	1330	last;
1126	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1331	}
1127	}	1332	}
1128	}	1333	}
1129		1334
1130	# check for already loaded models
1131	unless ($MODEL) {	1335	unless ($MODEL) {
		1336	# try to autoload a model
1132	for (@REGISTRY, @models) {	1337	for (@REGISTRY, @models) {
1133	my ($package, $model) = @$_;	1338	my ($package, $model, $autoload) = @$_;
		1339	if (
		1340	$autoload
		1341	and eval "require $package"
1134	if (${"$package\::VERSION"} > 0) {	1342	and ${"$package\::VERSION"} > 0
1135	if (eval "require $model") {	1343	and eval "require $model"
		1344	) {
1136	$MODEL = $model;	1345	$MODEL = $model;
1137	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1346	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1138	last;	1347	last;
1139	}
1140	}	1348	}
1141	}	1349	}
1142		1350
1143	unless ($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	1351	$MODEL
1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1352	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1159	}
1160	}	1353	}
1161
1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1163
1164	unshift @ISA, $MODEL;
1165
1166	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1167
1168	(shift @post_detect)->() while @post_detect;
1169	}	1354	}
1170		1355
		1356	# free memory only needed for probing
		1357	undef @models;
		1358	undef @REGISTRY;
		1359
		1360	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1361	unshift @ISA, $MODEL;
		1362
		1363	# now nuke some methods that are overridden by the backend.
		1364	# SUPER usage is not allowed in these.
		1365	for (qw(time signal child idle)) {
		1366	undef &{"AnyEvent::Base::$_"}
		1367	if defined &{"$MODEL\::$_"};
		1368	}
		1369
		1370	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1371	require AnyEvent::Strict;
		1372	}
		1373
		1374	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1375	require AnyEvent::Debug;
		1376	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1377	}
		1378
		1379	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1380	require AnyEvent::Debug;
		1381	#d#
		1382	}
		1383
		1384	(shift @post_detect)->() while @post_detect;
		1385	undef @post_detect;
		1386
		1387	*post_detect = sub(&) {
		1388	shift->();
		1389
		1390	undef
		1391	};
		1392
1171	$MODEL	1393	$MODEL
1172	}	1394	}
1173		1395
1174	sub AUTOLOAD {	1396	for my $name (@methods) {
1175	(my $func = $AUTOLOAD) =~ s/.*://;	1397	*$name = sub {
1176		1398	detect;
1177	$method{$func}	1399	# we use goto because
1178	or croak "$func: not a valid method for AnyEvent objects";	1400	# a) it makes the thunk more transparent
1179		1401	# b) it allows us to delete the thunk later
1180	detect unless $MODEL;	1402	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1181		1403	};
1182	my $class = shift;
1183	$class->$func (@_);
1184	}	1404	}
1185		1405
1186	# utility function to dup a filehandle. this is used by many backends	1406	# utility function to dup a filehandle. this is used by many backends
1187	# to support binding more than one watcher per filehandle (they usually	1407	# 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).	1408	# allow only one watcher per fd, so we dup it to get a different one).
1189	sub _dupfh($$;$$) {	1409	sub _dupfh($$;$$) {
1190	my ($poll, $fh, $r, $w) = @_;	1410	my ($poll, $fh, $r, $w) = @_;
1191		1411
1192	# cygwin requires the fh mode to be matching, unix doesn't	1412	# cygwin requires the fh mode to be matching, unix doesn't
1193	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");	1413	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1194		1414
1195	open my $fh2, "$mode&", $fh	1415	open my $fh2, $mode, $fh
1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";	1416	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1197		1417
1198	# we assume CLOEXEC is already set by perl in all important cases	1418	# we assume CLOEXEC is already set by perl in all important cases
1199		1419
1200	($fh2, $rw)	1420	($fh2, $rw)
1201	}	1421	}
1202		1422
		1423	=head1 SIMPLIFIED AE API
		1424
		1425	Starting with version 5.0, AnyEvent officially supports a second, much
		1426	simpler, API that is designed to reduce the calling, typing and memory
		1427	overhead by using function call syntax and a fixed number of parameters.
		1428
		1429	See the L<AE> manpage for details.
		1430
		1431	=cut
		1432
		1433	package AE;
		1434
		1435	our $VERSION = $AnyEvent::VERSION;
		1436
		1437	sub _reset() {
		1438	eval q{
		1439	# fall back to the main API by default - backends and AnyEvent::Base
		1440	# implementations can overwrite these.
		1441
		1442	sub io($$$) {
		1443	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1444	}
		1445
		1446	sub timer($$$) {
		1447	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1448	}
		1449
		1450	sub signal($$) {
		1451	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1452	}
		1453
		1454	sub child($$) {
		1455	AnyEvent->child (pid => $_[0], cb => $_[1])
		1456	}
		1457
		1458	sub idle($) {
		1459	AnyEvent->idle (cb => $_[0]);
		1460	}
		1461
		1462	sub cv(;&) {
		1463	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1464	}
		1465
		1466	sub now() {
		1467	AnyEvent->now
		1468	}
		1469
		1470	sub now_update() {
		1471	AnyEvent->now_update
		1472	}
		1473
		1474	sub time() {
		1475	AnyEvent->time
		1476	}
		1477
		1478	*postpone = \&AnyEvent::postpone;
		1479	};
		1480	die if $@;
		1481	}
		1482
		1483	BEGIN { _reset }
		1484
1203	package AnyEvent::Base;	1485	package AnyEvent::Base;
1204		1486
1205	# default implementations for many methods	1487	# default implementations for many methods
1206		1488
1207	BEGIN {	1489	sub time {
		1490	eval q{ # poor man's autoloading {}
		1491	# probe for availability of Time::HiRes
1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1492	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1493	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1209	*_time = \&Time::HiRes::time;	1494	*AE::time = \&Time::HiRes::time;
1210	# if (eval "use POSIX (); (POSIX::times())...	1495	# if (eval "use POSIX (); (POSIX::times())...
1211	} else {	1496	} else {
		1497	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1212	*_time = sub { time }; # epic fail	1498	*AE::time = sub (){ time }; # epic fail
		1499	}
		1500
		1501	*time = sub { AE::time }; # different prototypes
		1502	};
		1503	die if $@;
		1504
		1505	&time
		1506	}
		1507
		1508	*now = \&time;
		1509
		1510	sub now_update { }
		1511
		1512	sub _poll {
		1513	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1514	}
		1515
		1516	# default implementation for ->condvar
		1517	# in fact, the default should not be overwritten
		1518
		1519	sub condvar {
		1520	eval q{ # poor man's autoloading {}
		1521	*condvar = sub {
		1522	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1523	};
		1524
		1525	*AE::cv = sub (;&) {
		1526	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1527	};
		1528	};
		1529	die if $@;
		1530
		1531	&condvar
		1532	}
		1533
		1534	# default implementation for ->signal
		1535
		1536	our $HAVE_ASYNC_INTERRUPT;
		1537
		1538	sub _have_async_interrupt() {
		1539	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1540	&& eval "use Async::Interrupt 1.02 (); 1")
		1541	unless defined $HAVE_ASYNC_INTERRUPT;
		1542
		1543	$HAVE_ASYNC_INTERRUPT
		1544	}
		1545
		1546	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1547	our (%SIG_ASY, %SIG_ASY_W);
		1548	our ($SIG_COUNT, $SIG_TW);
		1549
		1550	# install a dummy wakeup watcher to reduce signal catching latency
		1551	# used by Impls
		1552	sub _sig_add() {
		1553	unless ($SIG_COUNT++) {
		1554	# try to align timer on a full-second boundary, if possible
		1555	my $NOW = AE::now;
		1556
		1557	$SIG_TW = AE::timer
		1558	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1559	$MAX_SIGNAL_LATENCY,
		1560	sub { } # just for the PERL_ASYNC_CHECK
		1561	;
1213	}	1562	}
1214	}	1563	}
1215		1564
1216	sub time { _time }	1565	sub _sig_del {
1217	sub now { _time }	1566	undef $SIG_TW
1218	sub now_update { }	1567	unless --$SIG_COUNT;
1219
1220	# default implementation for ->condvar
1221
1222	sub condvar {
1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1224	}	1568	}
1225		1569
1226	# default implementation for ->signal	1570	our $_sig_name_init; $_sig_name_init = sub {
		1571	eval q{ # poor man's autoloading {}
		1572	undef $_sig_name_init;
1227		1573
1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1574	if (_have_async_interrupt) {
		1575	*sig2num = \&Async::Interrupt::sig2num;
		1576	*sig2name = \&Async::Interrupt::sig2name;
		1577	} else {
		1578	require Config;
1229		1579
1230	sub _signal_exec {	1580	my %signame2num;
1231	sysread $SIGPIPE_R, my $dummy, 4;	1581	@signame2num{ split ' ', $Config::Config{sig_name} }
		1582	= split ' ', $Config::Config{sig_num};
1232		1583
1233	while (%SIG_EV) {	1584	my @signum2name;
1234	for (keys %SIG_EV) {	1585	@signum2name[values %signame2num] = keys %signame2num;
1235	delete $SIG_EV{$_};	1586
1236	$_->() for values %{ $SIG_CB{$_} || {} };	1587	*sig2num = sub($) {
		1588	$_[0] > 0 ? shift : $signame2num{+shift}
		1589	};
		1590	*sig2name = sub ($) {
		1591	$_[0] > 0 ? $signum2name[+shift] : shift
		1592	};
1237	}	1593	}
1238	}	1594	};
1239	}	1595	die if $@;
		1596	};
		1597
		1598	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1599	sub sig2name($) { &$_sig_name_init; &sig2name }
1240		1600
1241	sub signal {	1601	sub signal {
1242	my (undef, %arg) = @_;	1602	eval q{ # poor man's autoloading {}
		1603	# probe for availability of Async::Interrupt
		1604	if (_have_async_interrupt) {
		1605	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1243		1606
1244	unless ($SIGPIPE_R) {	1607	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1245	require Fcntl;	1608	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1246		1609
1247	if (AnyEvent::WIN32) {
1248	require AnyEvent::Util;
1249
1250	($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 {	1610	} else {
		1611	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1612
		1613	if (AnyEvent::WIN32) {
		1614	require AnyEvent::Util;
		1615
		1616	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1617	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1618	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1619	} else {
1254	pipe $SIGPIPE_R, $SIGPIPE_W;	1620	pipe $SIGPIPE_R, $SIGPIPE_W;
1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1621	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	1622	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1257		1623
1258	# not strictly required, as $^F is normally 2, but let's make sure...	1624	# not strictly required, as $^F is normally 2, but let's make sure...
1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1625	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1626	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1627	}
		1628
		1629	$SIGPIPE_R
		1630	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1631
		1632	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1261	}	1633	}
1262		1634
1263	$SIGPIPE_R	1635	*signal = $HAVE_ASYNC_INTERRUPT
1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1636	? sub {
		1637	my (undef, %arg) = @_;
1265		1638
1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1639	# async::interrupt
1267	}
1268
1269	my $signal = uc $arg{signal}	1640	my $signal = sig2num $arg{signal};
1270	or Carp::croak "required option 'signal' is missing";
1271
1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1641	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1642
		1643	$SIG_ASY{$signal} ||= new Async::Interrupt
		1644	cb => sub { undef $SIG_EV{$signal} },
		1645	signal => $signal,
		1646	pipe => [$SIGPIPE_R->filenos],
		1647	pipe_autodrain => 0,
		1648	;
		1649
		1650	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1651	}
		1652	: sub {
		1653	my (undef, %arg) = @_;
		1654
		1655	# pure perl
		1656	my $signal = sig2name $arg{signal};
		1657	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1658
1273	$SIG{$signal} ||= sub {	1659	$SIG{$signal} ||= sub {
1274	local $!;	1660	local $!;
1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1661	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1276	undef $SIG_EV{$signal};	1662	undef $SIG_EV{$signal};
		1663	};
		1664
		1665	# can't do signal processing without introducing races in pure perl,
		1666	# so limit the signal latency.
		1667	_sig_add;
		1668
		1669	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1670	}
		1671	;
		1672
		1673	*AnyEvent::Base::signal::DESTROY = sub {
		1674	my ($signal, $cb) = @{$_[0]};
		1675
		1676	_sig_del;
		1677
		1678	delete $SIG_CB{$signal}{$cb};
		1679
		1680	$HAVE_ASYNC_INTERRUPT
		1681	? delete $SIG_ASY{$signal}
		1682	: # delete doesn't work with older perls - they then
		1683	# print weird messages, or just unconditionally exit
		1684	# instead of getting the default action.
		1685	undef $SIG{$signal}
		1686	unless keys %{ $SIG_CB{$signal} };
		1687	};
		1688
		1689	*_signal_exec = sub {
		1690	$HAVE_ASYNC_INTERRUPT
		1691	? $SIGPIPE_R->drain
		1692	: sysread $SIGPIPE_R, (my $dummy), 9;
		1693
		1694	while (%SIG_EV) {
		1695	for (keys %SIG_EV) {
		1696	delete $SIG_EV{$_};
		1697	&$_ for values %{ $SIG_CB{$_} || {} };
		1698	}
		1699	}
		1700	};
1277	};	1701	};
		1702	die if $@;
1278		1703
1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1704	&signal
1280	}
1281
1282	sub AnyEvent::Base::signal::DESTROY {
1283	my ($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	}	1705	}
1292		1706
1293	# default implementation for ->child	1707	# default implementation for ->child
1294		1708
1295	our %PID_CB;	1709	our %PID_CB;
1296	our $CHLD_W;	1710	our $CHLD_W;
1297	our $CHLD_DELAY_W;	1711	our $CHLD_DELAY_W;
1298	our $WNOHANG;
1299		1712
1300	sub _sigchld {	1713	# used by many Impl's
1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1714	sub _emit_childstatus($$) {
		1715	my (undef, $rpid, $rstatus) = @_;
		1716
		1717	$_->($rpid, $rstatus)
1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1718	for values %{ $PID_CB{$rpid} || {} },
1303	(values %{ $PID_CB{0} || {} });	1719	values %{ $PID_CB{0} || {} };
1304	}
1305	}	1720	}
1306		1721
1307	sub child {	1722	sub child {
		1723	eval q{ # poor man's autoloading {}
		1724	*_sigchld = sub {
		1725	my $pid;
		1726
		1727	AnyEvent->_emit_childstatus ($pid, $?)
		1728	while ($pid = waitpid -1, WNOHANG) > 0;
		1729	};
		1730
		1731	*child = sub {
1308	my (undef, %arg) = @_;	1732	my (undef, %arg) = @_;
1309		1733
1310	defined (my $pid = $arg{pid} + 0)	1734	my $pid = $arg{pid};
1311	or Carp::croak "required option 'pid' is missing";	1735	my $cb = $arg{cb};
1312		1736
1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1737	$PID_CB{$pid}{$cb+0} = $cb;
1314		1738
1315	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1316
1317	unless ($CHLD_W) {	1739	unless ($CHLD_W) {
1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1740	$CHLD_W = AE::signal CHLD => \&_sigchld;
1319	# child could be a zombie already, so make at least one round	1741	# child could be a zombie already, so make at least one round
1320	&_sigchld;	1742	&_sigchld;
1321	}	1743	}
1322		1744
1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1745	bless [$pid, $cb+0], "AnyEvent::Base::child"
1324	}	1746	};
1325		1747
1326	sub AnyEvent::Base::child::DESTROY {	1748	*AnyEvent::Base::child::DESTROY = sub {
1327	my ($pid, $cb) = @{$_[0]};	1749	my ($pid, $icb) = @{$_[0]};
1328		1750
1329	delete $PID_CB{$pid}{$cb};	1751	delete $PID_CB{$pid}{$icb};
1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1752	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1331		1753
1332	undef $CHLD_W unless keys %PID_CB;	1754	undef $CHLD_W unless keys %PID_CB;
		1755	};
		1756	};
		1757	die if $@;
		1758
		1759	&child
1333	}	1760	}
1334		1761
1335	# idle emulation is done by simply using a timer, regardless	1762	# idle emulation is done by simply using a timer, regardless
1336	# of whether the process is idle or not, and not letting	1763	# of whether the process is idle or not, and not letting
1337	# the callback use more than 50% of the time.	1764	# the callback use more than 50% of the time.
1338	sub idle {	1765	sub idle {
		1766	eval q{ # poor man's autoloading {}
		1767	*idle = sub {
1339	my (undef, %arg) = @_;	1768	my (undef, %arg) = @_;
1340		1769
1341	my ($cb, $w, $rcb) = $arg{cb};	1770	my ($cb, $w, $rcb) = $arg{cb};
1342		1771
1343	$rcb = sub {	1772	$rcb = sub {
1344	if ($cb) {	1773	if ($cb) {
1345	$w = _time;	1774	$w = AE::time;
1346	&$cb;	1775	&$cb;
1347	$w = _time - $w;	1776	$w = AE::time - $w;
1348		1777
1349	# never use more then 50% of the time for the idle watcher,	1778	# never use more then 50% of the time for the idle watcher,
1350	# within some limits	1779	# within some limits
1351	$w = 0.0001 if $w < 0.0001;	1780	$w = 0.0001 if $w < 0.0001;
1352	$w = 5 if $w > 5;	1781	$w = 5 if $w > 5;
1353		1782
1354	$w = AnyEvent->timer (after => $w, cb => $rcb);	1783	$w = AE::timer $w, 0, $rcb;
1355	} else {	1784	} else {
1356	# clean up...	1785	# clean up...
1357	undef $w;	1786	undef $w;
1358	undef $rcb;	1787	undef $rcb;
		1788	}
		1789	};
		1790
		1791	$w = AE::timer 0.05, 0, $rcb;
		1792
		1793	bless \\$cb, "AnyEvent::Base::idle"
1359	}	1794	};
		1795
		1796	*AnyEvent::Base::idle::DESTROY = sub {
		1797	undef $${$_[0]};
		1798	};
1360	};	1799	};
		1800	die if $@;
1361		1801
1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1802	&idle
1363
1364	bless \\$cb, "AnyEvent::Base::idle"
1365	}
1366
1367	sub AnyEvent::Base::idle::DESTROY {
1368	undef $${$_[0]};
1369	}	1803	}
1370		1804
1371	package AnyEvent::CondVar;	1805	package AnyEvent::CondVar;
1372		1806
1373	our @ISA = AnyEvent::CondVar::Base::;	1807	our @ISA = AnyEvent::CondVar::Base::;
1374		1808
		1809	# only to be used for subclassing
		1810	sub new {
		1811	my $class = shift;
		1812	bless AnyEvent->condvar (@_), $class
		1813	}
		1814
1375	package AnyEvent::CondVar::Base;	1815	package AnyEvent::CondVar::Base;
1376		1816
1377	use overload	1817	#use overload
1378	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1818	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1379	fallback => 1;	1819	# fallback => 1;
		1820
		1821	# save 300+ kilobytes by dirtily hardcoding overloading
		1822	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1823	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1824	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1825	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1826
		1827	our $WAITING;
1380		1828
1381	sub _send {	1829	sub _send {
1382	# nop	1830	# nop
		1831	}
		1832
		1833	sub _wait {
		1834	AnyEvent->_poll until $_[0]{_ae_sent};
1383	}	1835	}
1384		1836
1385	sub send {	1837	sub send {
1386	my $cv = shift;	1838	my $cv = shift;
1387	$cv->{_ae_sent} = [@_];	1839	$cv->{_ae_sent} = [@_];
…		…
1396		1848
1397	sub ready {	1849	sub ready {
1398	$_[0]{_ae_sent}	1850	$_[0]{_ae_sent}
1399	}	1851	}
1400		1852
1401	sub _wait {
1402	AnyEvent->one_event while !$_[0]{_ae_sent};
1403	}
1404
1405	sub recv {	1853	sub recv {
		1854	unless ($_[0]{_ae_sent}) {
		1855	$WAITING
		1856	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1857
		1858	local $WAITING = 1;
1406	$_[0]->_wait;	1859	$_[0]->_wait;
		1860	}
1407		1861
1408	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1862	$_[0]{_ae_croak}
1409	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1863	and Carp::croak $_[0]{_ae_croak};
		1864
		1865	wantarray
		1866	? @{ $_[0]{_ae_sent} }
		1867	: $_[0]{_ae_sent}[0]
1410	}	1868	}
1411		1869
1412	sub cb {	1870	sub cb {
1413	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1871	my $cv = shift;
		1872
		1873	@_
		1874	and $cv->{_ae_cb} = shift
		1875	and $cv->{_ae_sent}
		1876	and (delete $cv->{_ae_cb})->($cv);
		1877
1414	$_[0]{_ae_cb}	1878	$cv->{_ae_cb}
1415	}	1879	}
1416		1880
1417	sub begin {	1881	sub begin {
1418	++$_[0]{_ae_counter};	1882	++$_[0]{_ae_counter};
1419	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1883	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1424	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1888	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1425	}	1889	}
1426		1890
1427	# undocumented/compatibility with pre-3.4	1891	# undocumented/compatibility with pre-3.4
1428	*broadcast = \&send;	1892	*broadcast = \&send;
1429	*wait = \&_wait;	1893	*wait = \&recv;
1430		1894
1431	=head1 ERROR AND EXCEPTION HANDLING	1895	=head1 ERROR AND EXCEPTION HANDLING
1432		1896
1433	In general, AnyEvent does not do any error handling - it relies on the	1897	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	1898	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1468	C<PERL_ANYEVENT_MODEL>.	1932	C<PERL_ANYEVENT_MODEL>.
1469		1933
1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1934	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1471	model it chooses.	1935	model it chooses.
1472		1936
		1937	When set to C<8> or higher, then AnyEvent will report extra information on
		1938	which optional modules it loads and how it implements certain features.
		1939
1473	=item C<PERL_ANYEVENT_STRICT>	1940	=item C<PERL_ANYEVENT_STRICT>
1474		1941
1475	AnyEvent does not do much argument checking by default, as thorough	1942	AnyEvent does not do much argument checking by default, as thorough
1476	argument checking is very costly. Setting this variable to a true value	1943	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	1944	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,	1945	check the arguments passed to most method calls. If it finds any problems,
1479	it will croak.	1946	it will croak.
1480		1947
1481	In other words, enables "strict" mode.	1948	In other words, enables "strict" mode.
1482		1949
1483	Unlike C<use strict>, it is definitely recommended to keep it off in	1950	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	1951	>>, it is definitely recommended to keep it off in production. Keeping
1485	developing programs can be very useful, however.	1952	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1953	can be very useful, however.
1486		1954
1487	=item C<PERL_ANYEVENT_MODEL>	1955	=item C<PERL_ANYEVENT_MODEL>
1488		1956
1489	This can be used to specify the event model to be used by AnyEvent, before	1957	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	1958	auto detection and -probing kicks in.
1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1959
		1960	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		1961	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,	1962	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	1963	event model backend. If it fails to load then AnyEvent will proceed with
1494	auto detection and -probing.	1964	auto detection and -probing.
1495		1965
1496	This functionality might change in future versions.	1966	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		1967	nothing gets prepended and the module name is used as-is (hint: C<::> at
		1968	the end of a string designates a module name and quotes it appropriately).
1497		1969
1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1970	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1499	could start your program like this:	1971	could start your program like this:
1500		1972
1501	PERL_ANYEVENT_MODEL=Perl perl ...	1973	PERL_ANYEVENT_MODEL=Perl perl ...
1502		1974
1503	=item C<PERL_ANYEVENT_PROTOCOLS>	1975	=item C<PERL_ANYEVENT_PROTOCOLS>
…		…
1552		2024
1553	When neither C<ca_file> nor C<ca_path> was specified during	2025	When neither C<ca_file> nor C<ca_path> was specified during
1554	L<AnyEvent::TLS> context creation, and either of these environment	2026	L<AnyEvent::TLS> context creation, and either of these environment
1555	variables exist, they will be used to specify CA certificate locations	2027	variables exist, they will be used to specify CA certificate locations
1556	instead of a system-dependent default.	2028	instead of a system-dependent default.
		2029
		2030	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2031
		2032	When these are set to C<1>, then the respective modules are not
		2033	loaded. Mostly good for testing AnyEvent itself.
1557		2034
1558	=back	2035	=back
1559		2036
1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2037	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1561		2038
…		…
1619	warn "read: $input\n"; # output what has been read	2096	warn "read: $input\n"; # output what has been read
1620	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2097	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1621	},	2098	},
1622	);	2099	);
1623		2100
1624	my $time_watcher; # can only be used once
1625
1626	sub new_timer {
1627	$timer = AnyEvent->timer (after => 1, cb => sub {	2101	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1628	warn "timeout\n"; # print 'timeout' about every second	2102	warn "timeout\n"; # print 'timeout' at most every second
1629	&new_timer; # and restart the time
1630	});	2103	});
1631	}
1632
1633	new_timer; # create first timer
1634		2104
1635	$cv->recv; # wait until user enters /^q/i	2105	$cv->recv; # wait until user enters /^q/i
1636		2106
1637	=head1 REAL-WORLD EXAMPLE	2107	=head1 REAL-WORLD EXAMPLE
1638		2108
…		…
1711		2181
1712	The actual code goes further and collects all errors (C<die>s, exceptions)	2182	The actual code goes further and collects all errors (C<die>s, exceptions)
1713	that occurred during request processing. The C<result> method detects	2183	that occurred during request processing. The C<result> method detects
1714	whether an exception as thrown (it is stored inside the $txn object)	2184	whether an exception as thrown (it is stored inside the $txn object)
1715	and just throws the exception, which means connection errors and other	2185	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	2186	problems get reported to the code that tries to use the result, not in a
1717	random callback.	2187	random callback.
1718		2188
1719	All of this enables the following usage styles:	2189	All of this enables the following usage styles:
1720		2190
1721	1. Blocking:	2191	1. Blocking:
…		…
1769	through AnyEvent. The benchmark creates a lot of timers (with a zero	2239	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,	2240	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.	2241	which it is), lets them fire exactly once and destroys them again.
1772		2242
1773	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2243	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1774	distribution.	2244	distribution. It uses the L<AE> interface, which makes a real difference
		2245	for the EV and Perl backends only.
1775		2246
1776	=head3 Explanation of the columns	2247	=head3 Explanation of the columns
1777		2248
1778	I<watcher> is the number of event watchers created/destroyed. Since	2249	I<watcher> is the number of event watchers created/destroyed. Since
1779	different event models feature vastly different performances, each event	2250	different event models feature vastly different performances, each event
…		…
1800	watcher.	2271	watcher.
1801		2272
1802	=head3 Results	2273	=head3 Results
1803		2274
1804	name watchers bytes create invoke destroy comment	2275	name watchers bytes create invoke destroy comment
1805	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2276	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	2277	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	2278	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	2279	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	2280	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	2281	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	2282	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	2283	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	2284	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	2285	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	2286	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	2287	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1817		2288
1818	=head3 Discussion	2289	=head3 Discussion
1819		2290
1820	The benchmark does I<not> measure scalability of the event loop very	2291	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)	2292	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	2304	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	2305	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1835	cycles with POE.	2306	cycles with POE.
1836		2307
1837	C<EV> is the sole leader regarding speed and memory use, which are both	2308	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	2309	maximal/minimal, respectively. When using the L<AE> API there is zero
		2310	overhead (when going through the AnyEvent API create is about 5-6 times
		2311	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	2312	any other event loop and is still faster than Event natively).
1840	natively.
1841		2313
1842	The pure perl implementation is hit in a few sweet spots (both the	2314	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	2315	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	2316	interpreter and the backend itself). Nevertheless this shows that it
1845	adds very little overhead in itself. Like any select-based backend its	2317	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	2391	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	2392	(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.	2393	connections, most of which are idle at any one point in time.
1922		2394
1923	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2395	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1924	distribution.	2396	distribution. It uses the L<AE> interface, which makes a real difference
		2397	for the EV and Perl backends only.
1925		2398
1926	=head3 Explanation of the columns	2399	=head3 Explanation of the columns
1927		2400
1928	I<sockets> is the number of sockets, and twice the number of "servers" (as	2401	I<sockets> is the number of sockets, and twice the number of "servers" (as
1929	each server has a read and write socket end).	2402	each server has a read and write socket end).
…		…
1937	a new one that moves the timeout into the future.	2410	a new one that moves the timeout into the future.
1938		2411
1939	=head3 Results	2412	=head3 Results
1940		2413
1941	name sockets create request	2414	name sockets create request
1942	EV 20000 69.01 11.16	2415	EV 20000 62.66 7.99
1943	Perl 20000 73.32 35.87	2416	Perl 20000 68.32 32.64
1944	IOAsync 20000 157.00 98.14 epoll	2417	IOAsync 20000 174.06 101.15 epoll
1945	IOAsync 20000 159.31 616.06 poll	2418	IOAsync 20000 174.67 610.84 poll
1946	Event 20000 212.62 257.32	2419	Event 20000 202.69 242.91
1947	Glib 20000 651.16 1896.30	2420	Glib 20000 557.01 1689.52
1948	POE 20000 349.67 12317.24 uses POE::Loop::Event	2421	POE 20000 341.54 12086.32 uses POE::Loop::Event
1949		2422
1950	=head3 Discussion	2423	=head3 Discussion
1951		2424
1952	This benchmark I<does> measure scalability and overall performance of the	2425	This benchmark I<does> measure scalability and overall performance of the
1953	particular event loop.	2426	particular event loop.
…		…
2079	As you can see, the AnyEvent + EV combination even beats the	2552	As you can see, the AnyEvent + EV combination even beats the
2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2553	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2081	backend easily beats IO::Lambda and POE.	2554	backend easily beats IO::Lambda and POE.
2082		2555
2083	And even the 100% non-blocking version written using the high-level (and	2556	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	2557	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	2558	higher level ("unoptimised") abstractions by a large margin, even though
2086	in a non-blocking way.	2559	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2087		2560
2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2561	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	2562	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.	2563	part of the IO::Lambda distribution and were used without any changes.
2091		2564
2092		2565
2093	=head1 SIGNALS	2566	=head1 SIGNALS
2094		2567
2095	AnyEvent currently installs handlers for these signals:	2568	AnyEvent currently installs handlers for these signals:
…		…
2100		2573
2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2574	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	2575	emulation for event loops that do not support them natively. Also, some
2103	event loops install a similar handler.	2576	event loops install a similar handler.
2104		2577
2105	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will	2578	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2106	reset it to default, to avoid losing child exit statuses.	2579	AnyEvent will reset it to default, to avoid losing child exit statuses.
2107		2580
2108	=item SIGPIPE	2581	=item SIGPIPE
2109		2582
2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2583	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2111	when AnyEvent gets loaded.	2584	when AnyEvent gets loaded.
…		…
2129	if $SIG{CHLD} eq 'IGNORE';	2602	if $SIG{CHLD} eq 'IGNORE';
2130		2603
2131	$SIG{PIPE} = sub { }	2604	$SIG{PIPE} = sub { }
2132	unless defined $SIG{PIPE};	2605	unless defined $SIG{PIPE};
2133		2606
		2607	=head1 RECOMMENDED/OPTIONAL MODULES
		2608
		2609	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2610	its built-in modules) are required to use it.
		2611
		2612	That does not mean that AnyEvent won't take advantage of some additional
		2613	modules if they are installed.
		2614
		2615	This section explains which additional modules will be used, and how they
		2616	affect AnyEvent's operation.
		2617
		2618	=over 4
		2619
		2620	=item L<Async::Interrupt>
		2621
		2622	This slightly arcane module is used to implement fast signal handling: To
		2623	my knowledge, there is no way to do completely race-free and quick
		2624	signal handling in pure perl. To ensure that signals still get
		2625	delivered, AnyEvent will start an interval timer to wake up perl (and
		2626	catch the signals) with some delay (default is 10 seconds, look for
		2627	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2628
		2629	If this module is available, then it will be used to implement signal
		2630	catching, which means that signals will not be delayed, and the event loop
		2631	will not be interrupted regularly, which is more efficient (and good for
		2632	battery life on laptops).
		2633
		2634	This affects not just the pure-perl event loop, but also other event loops
		2635	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2636
		2637	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2638	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2639	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2640	does nothing for those backends.
		2641
		2642	=item L<EV>
		2643
		2644	This module isn't really "optional", as it is simply one of the backend
		2645	event loops that AnyEvent can use. However, it is simply the best event
		2646	loop available in terms of features, speed and stability: It supports
		2647	the AnyEvent API optimally, implements all the watcher types in XS, does
		2648	automatic timer adjustments even when no monotonic clock is available,
		2649	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2650	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2651	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2652
		2653	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2654	then this module will do nothing for you.
		2655
		2656	=item L<Guard>
		2657
		2658	The guard module, when used, will be used to implement
		2659	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2660	lot less memory), but otherwise doesn't affect guard operation much. It is
		2661	purely used for performance.
		2662
		2663	=item L<JSON> and L<JSON::XS>
		2664
		2665	One of these modules is required when you want to read or write JSON data
		2666	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2667	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2668
		2669	=item L<Net::SSLeay>
		2670
		2671	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2672	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2673	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2674
		2675	=item L<Time::HiRes>
		2676
		2677	This module is part of perl since release 5.008. It will be used when the
		2678	chosen event library does not come with a timing source of its own. The
		2679	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2680	try to use a monotonic clock for timing stability.
		2681
		2682	=back
		2683
		2684
2134	=head1 FORK	2685	=head1 FORK
2135		2686
2136	Most event libraries are not fork-safe. The ones who are usually are	2687	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>	2688	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2138	calls. Only L<EV> is fully fork-aware.	2689	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2690	are usually badly thought-out hacks that are incompatible with fork in
		2691	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2692	continue event-processing in both parent and child (or both, if you know
		2693	what you are doing).
		2694
		2695	This means that, in general, you cannot fork and do event processing in
		2696	the child if the event library was initialised before the fork (which
		2697	usually happens when the first AnyEvent watcher is created, or the library
		2698	is loaded).
2139		2699
2140	If you have to fork, you must either do so I<before> creating your first	2700	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.	2701	watcher OR you must not use AnyEvent at all in the child OR you must do
		2702	something completely out of the scope of AnyEvent.
		2703
		2704	The problem of doing event processing in the parent I<and> the child
		2705	is much more complicated: even for backends that I<are> fork-aware or
		2706	fork-safe, their behaviour is not usually what you want: fork clones all
		2707	watchers, that means all timers, I/O watchers etc. are active in both
		2708	parent and child, which is almost never what you want. USing C<exec>
		2709	to start worker children from some kind of manage rprocess is usually
		2710	preferred, because it is much easier and cleaner, at the expense of having
		2711	to have another binary.
2142		2712
2143		2713
2144	=head1 SECURITY CONSIDERATIONS	2714	=head1 SECURITY CONSIDERATIONS
2145		2715
2146	AnyEvent can be forced to load any event model via	2716	AnyEvent can be forced to load any event model via
…		…
2176	pronounced).	2746	pronounced).
2177		2747
2178		2748
2179	=head1 SEE ALSO	2749	=head1 SEE ALSO
2180		2750
		2751	Tutorial/Introduction: L<AnyEvent::Intro>.
		2752
		2753	FAQ: L<AnyEvent::FAQ>.
		2754
2181	Utility functions: L<AnyEvent::Util>.	2755	Utility functions: L<AnyEvent::Util>.
2182		2756
2183	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2757	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>.	2758	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2185		2759
2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2760	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2761	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2762	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.	2763	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2190		2764
2191	Non-blocking file handles, sockets, TCP clients and	2765	Non-blocking file handles, sockets, TCP clients and
2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.	2766	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2193		2767
2194	Asynchronous DNS: L<AnyEvent::DNS>.	2768	Asynchronous DNS: L<AnyEvent::DNS>.
2195		2769
2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,	2770	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2197	L<Coro::Event>,
2198		2771
2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,	2772	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2200	L<AnyEvent::HTTP>.	2773	L<AnyEvent::HTTP>.
2201		2774
2202		2775
2203	=head1 AUTHOR	2776	=head1 AUTHOR
2204		2777

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