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Revision 1.361 by root, Sun Aug 14 01:38:14 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
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
745	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
746		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
747	=over 4	919	=over 4
748		920
749	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
750		922
751	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
752	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
753	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
754	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
755	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
756		930	will be C<urxvt::anyevent>).
757	The known classes so far are:
758
759	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
760	AnyEvent::Impl::Event based on Event, second best choice.
761	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
762	AnyEvent::Impl::Glib based on Glib, third-best choice.
763	AnyEvent::Impl::Tk based on Tk, very bad choice.
764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
767
768	# warning, support for IO::Async is only partial, as it is too broken
769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
771
772	There is no support for WxWidgets, as WxWidgets has no support for
773	watching file handles. However, you can use WxWidgets through the
774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
775	second, which was considered to be too horrible to even consider for
776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
777	it's adaptor.
778
779	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
780	autodetecting them.
781		931
782	=item AnyEvent::detect	932	=item AnyEvent::detect
783		933
784	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
785	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
786	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
787	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
788		945
789	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
790		947
791	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
792	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
793		961
794	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
795	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
796	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
797		982
798	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
799		984
800	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
801	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
802	the event loop has been chosen.	987	after the event loop has been chosen.
803		988
804	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
805	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
806	and the array will be ignored.	991	array will be ignored.
807		992
808	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
809		1053
810	=back	1054	=back
811		1055
812	=head1 WHAT TO DO IN A MODULE	1056	=head1 WHAT TO DO IN A MODULE
813		1057
…		…
824	because it will stall the whole program, and the whole point of using	1068	because it will stall the whole program, and the whole point of using
825	events is to stay interactive.	1069	events is to stay interactive.
826		1070
827	It is fine, however, to call C<< ->recv >> when the user of your module	1071	It is fine, however, to call C<< ->recv >> when the user of your module
828	requests it (i.e. if you create a http request object ad have a method	1072	requests it (i.e. if you create a http request object ad have a method
829	called C<results> that returns the results, it should call C<< ->recv >>	1073	called C<results> that returns the results, it may call C<< ->recv >>
830	freely, as the user of your module knows what she is doing. always).	1074	freely, as the user of your module knows what she is doing. Always).
831		1075
832	=head1 WHAT TO DO IN THE MAIN PROGRAM	1076	=head1 WHAT TO DO IN THE MAIN PROGRAM
833		1077
834	There will always be a single main program - the only place that should	1078	There will always be a single main program - the only place that should
835	dictate which event model to use.	1079	dictate which event model to use.
836		1080
837	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1081	If the program is not event-based, it need not do anything special, even
838	do anything special (it does not need to be event-based) and let AnyEvent	1082	when it depends on a module that uses an AnyEvent. If the program itself
839	decide which implementation to chose if some module relies on it.	1083	uses AnyEvent, but does not care which event loop is used, all it needs
		1084	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1085	available loop implementation.
840		1086
841	If the main program relies on a specific event model - for example, in	1087	If the main program relies on a specific event model - for example, in
842	Gtk2 programs you have to rely on the Glib module - you should load the	1088	Gtk2 programs you have to rely on the Glib module - you should load the
843	event module before loading AnyEvent or any module that uses it: generally	1089	event module before loading AnyEvent or any module that uses it: generally
844	speaking, you should load it as early as possible. The reason is that	1090	speaking, you should load it as early as possible. The reason is that
845	modules might create watchers when they are loaded, and AnyEvent will	1091	modules might create watchers when they are loaded, and AnyEvent will
846	decide on the event model to use as soon as it creates watchers, and it	1092	decide on the event model to use as soon as it creates watchers, and it
847	might chose the wrong one unless you load the correct one yourself.	1093	might choose the wrong one unless you load the correct one yourself.
848		1094
849	You can chose to use a pure-perl implementation by loading the	1095	You can chose to use a pure-perl implementation by loading the
850	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1096	C<AnyEvent::Loop> module, which gives you similar behaviour
851	everywhere, but letting AnyEvent chose the model is generally better.	1097	everywhere, but letting AnyEvent chose the model is generally better.
852		1098
853	=head2 MAINLOOP EMULATION	1099	=head2 MAINLOOP EMULATION
854		1100
855	Sometimes (often for short test scripts, or even standalone programs who	1101	Sometimes (often for short test scripts, or even standalone programs who
…		…
870	=head1 OTHER MODULES	1116	=head1 OTHER MODULES
871		1117
872	The following is a non-exhaustive list of additional modules that use	1118	The following is a non-exhaustive list of additional modules that use
873	AnyEvent as a client and can therefore be mixed easily with other AnyEvent	1119	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
874	modules and other event loops in the same program. Some of the modules	1120	modules and other event loops in the same program. Some of the modules
875	come with AnyEvent, most are available via CPAN.	1121	come as part of AnyEvent, the others are available via CPAN.
876		1122
877	=over 4	1123	=over 4
878		1124
879	=item L<AnyEvent::Util>	1125	=item L<AnyEvent::Util>
880		1126
881	Contains various utility functions that replace often-used but blocking	1127	Contains various utility functions that replace often-used blocking
882	functions such as C<inet_aton> by event-/callback-based versions.	1128	functions such as C<inet_aton> with event/callback-based versions.
883		1129
884	=item L<AnyEvent::Socket>	1130	=item L<AnyEvent::Socket>
885		1131
886	Provides various utility functions for (internet protocol) sockets,	1132	Provides various utility functions for (internet protocol) sockets,
887	addresses and name resolution. Also functions to create non-blocking tcp	1133	addresses and name resolution. Also functions to create non-blocking tcp
…		…
889		1135
890	=item L<AnyEvent::Handle>	1136	=item L<AnyEvent::Handle>
891		1137
892	Provide read and write buffers, manages watchers for reads and writes,	1138	Provide read and write buffers, manages watchers for reads and writes,
893	supports raw and formatted I/O, I/O queued and fully transparent and	1139	supports raw and formatted I/O, I/O queued and fully transparent and
894	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1140	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
895		1141
896	=item L<AnyEvent::DNS>	1142	=item L<AnyEvent::DNS>
897		1143
898	Provides rich asynchronous DNS resolver capabilities.	1144	Provides rich asynchronous DNS resolver capabilities.
899		1145
		1146	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1147
		1148	Implement event-based interfaces to the protocols of the same name (for
		1149	the curious, IGS is the International Go Server and FCP is the Freenet
		1150	Client Protocol).
		1151
		1152	=item L<AnyEvent::Handle::UDP>
		1153
		1154	Here be danger!
		1155
		1156	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1157	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1158	its use of a stream-based API with a protocol that isn't streamable, that
		1159	the only way to improve it is to delete it.
		1160
		1161	It features data corruption (but typically only under load) and general
		1162	confusion. On top, the author is not only clueless about UDP but also
		1163	fact-resistant - some gems of his understanding: "connect doesn't work
		1164	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1165	packets", "I don't need to implement proper error checking as UDP doesn't
		1166	support error checking" and so on - he doesn't even understand what's
		1167	wrong with his module when it is explained to him.
		1168
900	=item L<AnyEvent::HTTP>	1169	=item L<AnyEvent::DBI>
901		1170
902	A simple-to-use HTTP library that is capable of making a lot of concurrent	1171	Executes L<DBI> requests asynchronously in a proxy process for you,
903	HTTP requests.	1172	notifying you in an event-based way when the operation is finished.
		1173
		1174	=item L<AnyEvent::AIO>
		1175
		1176	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1177	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1178	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1179	file I/O, and much more.
904		1180
905	=item L<AnyEvent::HTTPD>	1181	=item L<AnyEvent::HTTPD>
906		1182
907	Provides a simple web application server framework.	1183	A simple embedded webserver.
908		1184
909	=item L<AnyEvent::FastPing>	1185	=item L<AnyEvent::FastPing>
910		1186
911	The fastest ping in the west.	1187	The fastest ping in the west.
912		1188
913	=item L<AnyEvent::DBI>
914
915	Executes L<DBI> requests asynchronously in a proxy process.
916
917	=item L<AnyEvent::AIO>
918
919	Truly asynchronous I/O, should be in the toolbox of every event
920	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
921	together.
922
923	=item L<AnyEvent::BDB>
924
925	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
926	L<BDB> and AnyEvent together.
927
928	=item L<AnyEvent::GPSD>
929
930	A non-blocking interface to gpsd, a daemon delivering GPS information.
931
932	=item L<AnyEvent::IRC>
933
934	AnyEvent based IRC client module family (replacing the older Net::IRC3).
935
936	=item L<AnyEvent::XMPP>
937
938	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
939	Net::XMPP2>.
940
941	=item L<AnyEvent::IGS>
942
943	A non-blocking interface to the Internet Go Server protocol (used by
944	L<App::IGS>).
945
946	=item L<Net::FCP>
947
948	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
949	of AnyEvent.
950
951	=item L<Event::ExecFlow>
952
953	High level API for event-based execution flow control.
954
955	=item L<Coro>	1189	=item L<Coro>
956		1190
957	Has special support for AnyEvent via L<Coro::AnyEvent>.	1191	Has special support for AnyEvent via L<Coro::AnyEvent>.
958		1192
959	=back	1193	=back
960		1194
961	=cut	1195	=cut
962		1196
963	package AnyEvent;	1197	package AnyEvent;
964		1198
965	no warnings;	1199	# basically a tuned-down version of common::sense
966	use strict qw(vars subs);	1200	sub common_sense {
		1201	# from common:.sense 3.4
		1202	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1203	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1204	$^H |= 0x00000600;
		1205	}
967		1206
		1207	BEGIN { AnyEvent::common_sense }
		1208
968	use Carp;	1209	use Carp ();
969		1210
970	our $VERSION = 4.801;	1211	our $VERSION = '6.01';
971	our $MODEL;	1212	our $MODEL;
972		1213
973	our $AUTOLOAD;
974	our @ISA;	1214	our @ISA;
975		1215
976	our @REGISTRY;	1216	our @REGISTRY;
977		1217
978	our $WIN32;	1218	our $VERBOSE;
979		1219
980	BEGIN {	1220	BEGIN {
981	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1221	require "AnyEvent/constants.pl";
		1222
982	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1223	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
983		1224
984	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1225	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
985	if ${^TAINT};	1226	if ${^TAINT};
986	}
987		1227
988	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1228	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1229
		1230	}
		1231
		1232	our $MAX_SIGNAL_LATENCY = 10;
989		1233
990	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1234	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
991		1235
992	{	1236	{
993	my $idx;	1237	my $idx;
994	$PROTOCOL{$_} = ++$idx	1238	$PROTOCOL{$_} = ++$idx
995	for reverse split /\s*,\s*/,	1239	for reverse split /\s*,\s*/,
996	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1240	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
997	}	1241	}
998		1242
		1243	our @post_detect;
		1244
		1245	sub post_detect(&) {
		1246	my ($cb) = @_;
		1247
		1248	push @post_detect, $cb;
		1249
		1250	defined wantarray
		1251	? bless \$cb, "AnyEvent::Util::postdetect"
		1252	: ()
		1253	}
		1254
		1255	sub AnyEvent::Util::postdetect::DESTROY {
		1256	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1257	}
		1258
		1259	our $POSTPONE_W;
		1260	our @POSTPONE;
		1261
		1262	sub _postpone_exec {
		1263	undef $POSTPONE_W;
		1264
		1265	&{ shift @POSTPONE }
		1266	while @POSTPONE;
		1267	}
		1268
		1269	sub postpone(&) {
		1270	push @POSTPONE, shift;
		1271
		1272	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1273
		1274	()
		1275	}
		1276
999	my @models = (	1277	our @models = (
1000	[EV:: => AnyEvent::Impl::EV::],	1278	[EV:: => AnyEvent::Impl::EV:: , 1],
1001	[Event:: => AnyEvent::Impl::Event::],	1279	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
1002	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
1003	# everything below here will not be autoprobed	1280	# everything below here will not (normally) be autoprobed
1004	# as the pureperl backend should work everywhere	1281	# as the pure perl backend should work everywhere
1005	# and is usually faster	1282	# and is usually faster
		1283	[Event:: => AnyEvent::Impl::Event::, 1],
		1284	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1285	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1286	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1006	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1287	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1007	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
1008	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
1009	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1288	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1010	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1289	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1011	[Wx:: => AnyEvent::Impl::POE::],	1290	[Wx:: => AnyEvent::Impl::POE::],
1012	[Prima:: => AnyEvent::Impl::POE::],	1291	[Prima:: => AnyEvent::Impl::POE::],
1013	# IO::Async is just too broken - we would need workaorunds for its	1292	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
1014	# byzantine signal and broken child handling, among others.	1293	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
1015	# IO::Async is rather hard to detect, as it doesn't have any	1294	[FLTK:: => AnyEvent::Impl::FLTK2::],
1016	# obvious default class.
1017	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1018	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1019	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
1020	);	1295	);
1021		1296
1022	our %method = map +($_ => 1),	1297	our @isa_hook;
		1298
		1299	sub _isa_set {
		1300	my @pkg = ("AnyEvent", (grep defined, map $_->[0], @isa_hook), $MODEL);
		1301
		1302	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1303	for 1 .. $#pkg;
		1304
		1305	grep $_->[1], @isa_hook
		1306	and AE::_reset ();
		1307	}
		1308
		1309	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1310	sub _isa_hook($$;$) {
		1311	my ($i, $pkg, $reset_ae) = @_;
		1312
		1313	$isa_hook[$i] = [$pkg, $reset_ae];
		1314
		1315	_isa_set;
		1316	}
		1317
		1318	# all autoloaded methods reserve the complete glob, not just the method slot.
		1319	# due to bugs in perls method cache implementation.
1023	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1320	our @methods = qw(io timer time now now_update signal child idle condvar);
1024		1321
1025	our @post_detect;
1026
1027	sub post_detect(&) {	1322	sub detect() {
1028	my ($cb) = @_;	1323	local $!; # for good measure
		1324	local $SIG{__DIE__}; # we use eval
1029		1325
1030	if ($MODEL) {	1326	# free some memory
1031	$cb->();	1327	*detect = sub () { $MODEL };
		1328	# undef &func doesn't correctly update the method cache. grmbl.
		1329	# so we delete the whole glob. grmbl.
		1330	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1331	# a glob with an active sub. hrm. i hope it works, but perl is
		1332	# usually buggy in this department. sigh.
		1333	delete @{"AnyEvent::"}{@methods};
		1334	undef @methods;
1032		1335
1033	1	1336	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1337	my $model = $1;
		1338	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1339	if (eval "require $model") {
		1340	$MODEL = $model;
		1341	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1034	} else {	1342	} else {
1035	push @post_detect, $cb;	1343	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1036		1344	}
1037	defined wantarray
1038	? bless \$cb, "AnyEvent::Util::postdetect"
1039	: ()
1040	}	1345	}
1041	}
1042		1346
1043	sub AnyEvent::Util::postdetect::DESTROY {	1347	# check for already loaded models
1044	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1045	}
1046
1047	sub detect() {
1048	unless ($MODEL) {	1348	unless ($MODEL) {
1049	no strict 'refs';	1349	for (@REGISTRY, @models) {
1050	local $SIG{__DIE__};	1350	my ($package, $model) = @$_;
1051		1351	if (${"$package\::VERSION"} > 0) {
1052	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1053	my $model = "AnyEvent::Impl::$1";
1054	if (eval "require $model") {	1352	if (eval "require $model") {
1055	$MODEL = $model;	1353	$MODEL = $model;
1056	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1354	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1057	} else {	1355	last;
1058	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1356	}
1059	}	1357	}
1060	}	1358	}
1061		1359
1062	# check for already loaded models
1063	unless ($MODEL) {	1360	unless ($MODEL) {
		1361	# try to autoload a model
1064	for (@REGISTRY, @models) {	1362	for (@REGISTRY, @models) {
1065	my ($package, $model) = @$_;	1363	my ($package, $model, $autoload) = @$_;
		1364	if (
		1365	$autoload
		1366	and eval "require $package"
1066	if (${"$package\::VERSION"} > 0) {	1367	and ${"$package\::VERSION"} > 0
1067	if (eval "require $model") {	1368	and eval "require $model"
		1369	) {
1068	$MODEL = $model;	1370	$MODEL = $model;
1069	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1371	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1070	last;	1372	last;
1071	}
1072	}	1373	}
1073	}	1374	}
1074		1375
1075	unless ($MODEL) {
1076	# try to load a model
1077
1078	for (@REGISTRY, @models) {
1079	my ($package, $model) = @$_;
1080	if (eval "require $package"
1081	and ${"$package\::VERSION"} > 0
1082	and eval "require $model") {
1083	$MODEL = $model;
1084	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1085	last;
1086	}
1087	}
1088
1089	$MODEL	1376	$MODEL
1090	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1377	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1091	}
1092	}	1378	}
1093
1094	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1095
1096	unshift @ISA, $MODEL;
1097
1098	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1099
1100	(shift @post_detect)->() while @post_detect;
1101	}	1379	}
1102		1380
		1381	# free memory only needed for probing
		1382	undef @models;
		1383	undef @REGISTRY;
		1384
		1385	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1386
		1387	# now nuke some methods that are overridden by the backend.
		1388	# SUPER usage is not allowed in these.
		1389	for (qw(time signal child idle)) {
		1390	undef &{"AnyEvent::Base::$_"}
		1391	if defined &{"$MODEL\::$_"};
		1392	}
		1393
		1394	_isa_set;
		1395
		1396	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1397	require AnyEvent::Strict;
		1398	}
		1399
		1400	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1401	require AnyEvent::Debug;
		1402	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1403	}
		1404
		1405	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1406	require AnyEvent::Socket;
		1407	require AnyEvent::Debug;
		1408
		1409	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1410	$shell =~ s/\$\$/$$/g;
		1411
		1412	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1413	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1414	}
		1415
		1416	(shift @post_detect)->() while @post_detect;
		1417	undef @post_detect;
		1418
		1419	*post_detect = sub(&) {
		1420	shift->();
		1421
		1422	undef
		1423	};
		1424
1103	$MODEL	1425	$MODEL
1104	}	1426	}
1105		1427
1106	sub AUTOLOAD {	1428	for my $name (@methods) {
1107	(my $func = $AUTOLOAD) =~ s/.*://;	1429	*$name = sub {
1108		1430	detect;
1109	$method{$func}	1431	# we use goto because
1110	or croak "$func: not a valid method for AnyEvent objects";	1432	# a) it makes the thunk more transparent
1111		1433	# b) it allows us to delete the thunk later
1112	detect unless $MODEL;	1434	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1113		1435	};
1114	my $class = shift;
1115	$class->$func (@_);
1116	}	1436	}
1117		1437
1118	# utility function to dup a filehandle. this is used by many backends	1438	# utility function to dup a filehandle. this is used by many backends
1119	# to support binding more than one watcher per filehandle (they usually	1439	# to support binding more than one watcher per filehandle (they usually
1120	# allow only one watcher per fd, so we dup it to get a different one).	1440	# allow only one watcher per fd, so we dup it to get a different one).
1121	sub _dupfh($$;$$) {	1441	sub _dupfh($$;$$) {
1122	my ($poll, $fh, $r, $w) = @_;	1442	my ($poll, $fh, $r, $w) = @_;
1123		1443
1124	# cygwin requires the fh mode to be matching, unix doesn't	1444	# cygwin requires the fh mode to be matching, unix doesn't
1125	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");	1445	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1126		1446
1127	open my $fh2, "$mode&", $fh	1447	open my $fh2, $mode, $fh
1128	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";	1448	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1129		1449
1130	# we assume CLOEXEC is already set by perl in all important cases	1450	# we assume CLOEXEC is already set by perl in all important cases
1131		1451
1132	($fh2, $rw)	1452	($fh2, $rw)
1133	}	1453	}
1134		1454
		1455	=head1 SIMPLIFIED AE API
		1456
		1457	Starting with version 5.0, AnyEvent officially supports a second, much
		1458	simpler, API that is designed to reduce the calling, typing and memory
		1459	overhead by using function call syntax and a fixed number of parameters.
		1460
		1461	See the L<AE> manpage for details.
		1462
		1463	=cut
		1464
		1465	package AE;
		1466
		1467	our $VERSION = $AnyEvent::VERSION;
		1468
		1469	sub _reset() {
		1470	eval q{
		1471	# fall back to the main API by default - backends and AnyEvent::Base
		1472	# implementations can overwrite these.
		1473
		1474	sub io($$$) {
		1475	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1476	}
		1477
		1478	sub timer($$$) {
		1479	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1480	}
		1481
		1482	sub signal($$) {
		1483	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1484	}
		1485
		1486	sub child($$) {
		1487	AnyEvent->child (pid => $_[0], cb => $_[1])
		1488	}
		1489
		1490	sub idle($) {
		1491	AnyEvent->idle (cb => $_[0]);
		1492	}
		1493
		1494	sub cv(;&) {
		1495	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1496	}
		1497
		1498	sub now() {
		1499	AnyEvent->now
		1500	}
		1501
		1502	sub now_update() {
		1503	AnyEvent->now_update
		1504	}
		1505
		1506	sub time() {
		1507	AnyEvent->time
		1508	}
		1509
		1510	*postpone = \&AnyEvent::postpone;
		1511	};
		1512	die if $@;
		1513	}
		1514
		1515	BEGIN { _reset }
		1516
1135	package AnyEvent::Base;	1517	package AnyEvent::Base;
1136		1518
1137	# default implementations for many methods	1519	# default implementations for many methods
1138		1520
1139	BEGIN {	1521	sub time {
		1522	eval q{ # poor man's autoloading {}
		1523	# probe for availability of Time::HiRes
1140	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1524	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1525	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1526	*time = sub { Time::HiRes::time () };
1141	*_time = \&Time::HiRes::time;	1527	*AE::time = \& Time::HiRes::time ;
1142	# if (eval "use POSIX (); (POSIX::times())...	1528	# if (eval "use POSIX (); (POSIX::times())...
1143	} else {	1529	} else {
1144	*_time = sub { time }; # epic fail	1530	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1531	*time = sub { CORE::time };
		1532	*AE::time = sub (){ CORE::time };
		1533	}
		1534
		1535	*now = \&time;
		1536	};
		1537	die if $@;
		1538
		1539	&time
		1540	}
		1541
		1542	*now = \&time;
		1543	sub now_update { }
		1544
		1545	sub _poll {
		1546	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1547	}
		1548
		1549	# default implementation for ->condvar
		1550	# in fact, the default should not be overwritten
		1551
		1552	sub condvar {
		1553	eval q{ # poor man's autoloading {}
		1554	*condvar = sub {
		1555	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1556	};
		1557
		1558	*AE::cv = sub (;&) {
		1559	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1560	};
		1561	};
		1562	die if $@;
		1563
		1564	&condvar
		1565	}
		1566
		1567	# default implementation for ->signal
		1568
		1569	our $HAVE_ASYNC_INTERRUPT;
		1570
		1571	sub _have_async_interrupt() {
		1572	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1573	&& eval "use Async::Interrupt 1.02 (); 1")
		1574	unless defined $HAVE_ASYNC_INTERRUPT;
		1575
		1576	$HAVE_ASYNC_INTERRUPT
		1577	}
		1578
		1579	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1580	our (%SIG_ASY, %SIG_ASY_W);
		1581	our ($SIG_COUNT, $SIG_TW);
		1582
		1583	# install a dummy wakeup watcher to reduce signal catching latency
		1584	# used by Impls
		1585	sub _sig_add() {
		1586	unless ($SIG_COUNT++) {
		1587	# try to align timer on a full-second boundary, if possible
		1588	my $NOW = AE::now;
		1589
		1590	$SIG_TW = AE::timer
		1591	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1592	$MAX_SIGNAL_LATENCY,
		1593	sub { } # just for the PERL_ASYNC_CHECK
		1594	;
1145	}	1595	}
1146	}	1596	}
1147		1597
1148	sub time { _time }	1598	sub _sig_del {
1149	sub now { _time }	1599	undef $SIG_TW
1150	sub now_update { }	1600	unless --$SIG_COUNT;
1151
1152	# default implementation for ->condvar
1153
1154	sub condvar {
1155	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1156	}	1601	}
1157		1602
1158	# default implementation for ->signal	1603	our $_sig_name_init; $_sig_name_init = sub {
		1604	eval q{ # poor man's autoloading {}
		1605	undef $_sig_name_init;
1159		1606
1160	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1607	if (_have_async_interrupt) {
		1608	*sig2num = \&Async::Interrupt::sig2num;
		1609	*sig2name = \&Async::Interrupt::sig2name;
		1610	} else {
		1611	require Config;
1161		1612
1162	sub _signal_exec {	1613	my %signame2num;
1163	sysread $SIGPIPE_R, my $dummy, 4;	1614	@signame2num{ split ' ', $Config::Config{sig_name} }
		1615	= split ' ', $Config::Config{sig_num};
1164		1616
1165	while (%SIG_EV) {	1617	my @signum2name;
1166	for (keys %SIG_EV) {	1618	@signum2name[values %signame2num] = keys %signame2num;
1167	delete $SIG_EV{$_};	1619
1168	$_->() for values %{ $SIG_CB{$_} || {} };	1620	*sig2num = sub($) {
		1621	$_[0] > 0 ? shift : $signame2num{+shift}
		1622	};
		1623	*sig2name = sub ($) {
		1624	$_[0] > 0 ? $signum2name[+shift] : shift
		1625	};
1169	}	1626	}
1170	}	1627	};
1171	}	1628	die if $@;
		1629	};
		1630
		1631	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1632	sub sig2name($) { &$_sig_name_init; &sig2name }
1172		1633
1173	sub signal {	1634	sub signal {
1174	my (undef, %arg) = @_;	1635	eval q{ # poor man's autoloading {}
		1636	# probe for availability of Async::Interrupt
		1637	if (_have_async_interrupt) {
		1638	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1175		1639
1176	unless ($SIGPIPE_R) {	1640	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1177	require Fcntl;	1641	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1178		1642
1179	if (AnyEvent::WIN32) {
1180	require AnyEvent::Util;
1181
1182	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1183	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1184	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1185	} else {	1643	} else {
		1644	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1645
		1646	if (AnyEvent::WIN32) {
		1647	require AnyEvent::Util;
		1648
		1649	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1650	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1651	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1652	} else {
1186	pipe $SIGPIPE_R, $SIGPIPE_W;	1653	pipe $SIGPIPE_R, $SIGPIPE_W;
1187	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1654	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1188	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1655	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1189		1656
1190	# not strictly required, as $^F is normally 2, but let's make sure...	1657	# not strictly required, as $^F is normally 2, but let's make sure...
1191	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1658	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1192	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1659	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1660	}
		1661
		1662	$SIGPIPE_R
		1663	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1664
		1665	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1193	}	1666	}
1194		1667
1195	$SIGPIPE_R	1668	*signal = $HAVE_ASYNC_INTERRUPT
1196	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1669	? sub {
		1670	my (undef, %arg) = @_;
1197		1671
1198	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1672	# async::interrupt
1199	}
1200
1201	my $signal = uc $arg{signal}	1673	my $signal = sig2num $arg{signal};
1202	or Carp::croak "required option 'signal' is missing";
1203
1204	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1674	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1675
		1676	$SIG_ASY{$signal} ||= new Async::Interrupt
		1677	cb => sub { undef $SIG_EV{$signal} },
		1678	signal => $signal,
		1679	pipe => [$SIGPIPE_R->filenos],
		1680	pipe_autodrain => 0,
		1681	;
		1682
		1683	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1684	}
		1685	: sub {
		1686	my (undef, %arg) = @_;
		1687
		1688	# pure perl
		1689	my $signal = sig2name $arg{signal};
		1690	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1691
1205	$SIG{$signal} ||= sub {	1692	$SIG{$signal} ||= sub {
1206	local $!;	1693	local $!;
1207	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1694	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1208	undef $SIG_EV{$signal};	1695	undef $SIG_EV{$signal};
		1696	};
		1697
		1698	# can't do signal processing without introducing races in pure perl,
		1699	# so limit the signal latency.
		1700	_sig_add;
		1701
		1702	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1703	}
		1704	;
		1705
		1706	*AnyEvent::Base::signal::DESTROY = sub {
		1707	my ($signal, $cb) = @{$_[0]};
		1708
		1709	_sig_del;
		1710
		1711	delete $SIG_CB{$signal}{$cb};
		1712
		1713	$HAVE_ASYNC_INTERRUPT
		1714	? delete $SIG_ASY{$signal}
		1715	: # delete doesn't work with older perls - they then
		1716	# print weird messages, or just unconditionally exit
		1717	# instead of getting the default action.
		1718	undef $SIG{$signal}
		1719	unless keys %{ $SIG_CB{$signal} };
		1720	};
		1721
		1722	*_signal_exec = sub {
		1723	$HAVE_ASYNC_INTERRUPT
		1724	? $SIGPIPE_R->drain
		1725	: sysread $SIGPIPE_R, (my $dummy), 9;
		1726
		1727	while (%SIG_EV) {
		1728	for (keys %SIG_EV) {
		1729	delete $SIG_EV{$_};
		1730	&$_ for values %{ $SIG_CB{$_} || {} };
		1731	}
		1732	}
		1733	};
1209	};	1734	};
		1735	die if $@;
1210		1736
1211	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1737	&signal
1212	}
1213
1214	sub AnyEvent::Base::signal::DESTROY {
1215	my ($signal, $cb) = @{$_[0]};
1216
1217	delete $SIG_CB{$signal}{$cb};
1218
1219	# delete doesn't work with older perls - they then
1220	# print weird messages, or just unconditionally exit
1221	# instead of getting the default action.
1222	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1223	}	1738	}
1224		1739
1225	# default implementation for ->child	1740	# default implementation for ->child
1226		1741
1227	our %PID_CB;	1742	our %PID_CB;
1228	our $CHLD_W;	1743	our $CHLD_W;
1229	our $CHLD_DELAY_W;	1744	our $CHLD_DELAY_W;
1230	our $WNOHANG;
1231		1745
1232	sub _sigchld {	1746	# used by many Impl's
1233	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1747	sub _emit_childstatus($$) {
		1748	my (undef, $rpid, $rstatus) = @_;
		1749
		1750	$_->($rpid, $rstatus)
1234	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1751	for values %{ $PID_CB{$rpid} || {} },
1235	(values %{ $PID_CB{0} || {} });	1752	values %{ $PID_CB{0} || {} };
1236	}
1237	}	1753	}
1238		1754
1239	sub child {	1755	sub child {
		1756	eval q{ # poor man's autoloading {}
		1757	*_sigchld = sub {
		1758	my $pid;
		1759
		1760	AnyEvent->_emit_childstatus ($pid, $?)
		1761	while ($pid = waitpid -1, WNOHANG) > 0;
		1762	};
		1763
		1764	*child = sub {
1240	my (undef, %arg) = @_;	1765	my (undef, %arg) = @_;
1241		1766
1242	defined (my $pid = $arg{pid} + 0)	1767	my $pid = $arg{pid};
1243	or Carp::croak "required option 'pid' is missing";	1768	my $cb = $arg{cb};
1244		1769
1245	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1770	$PID_CB{$pid}{$cb+0} = $cb;
1246		1771
1247	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1248
1249	unless ($CHLD_W) {	1772	unless ($CHLD_W) {
1250	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1773	$CHLD_W = AE::signal CHLD => \&_sigchld;
1251	# child could be a zombie already, so make at least one round	1774	# child could be a zombie already, so make at least one round
1252	&_sigchld;	1775	&_sigchld;
1253	}	1776	}
1254		1777
1255	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1778	bless [$pid, $cb+0], "AnyEvent::Base::child"
1256	}	1779	};
1257		1780
1258	sub AnyEvent::Base::child::DESTROY {	1781	*AnyEvent::Base::child::DESTROY = sub {
1259	my ($pid, $cb) = @{$_[0]};	1782	my ($pid, $icb) = @{$_[0]};
1260		1783
1261	delete $PID_CB{$pid}{$cb};	1784	delete $PID_CB{$pid}{$icb};
1262	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1785	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1263		1786
1264	undef $CHLD_W unless keys %PID_CB;	1787	undef $CHLD_W unless keys %PID_CB;
		1788	};
		1789	};
		1790	die if $@;
		1791
		1792	&child
1265	}	1793	}
1266		1794
1267	# idle emulation is done by simply using a timer, regardless	1795	# idle emulation is done by simply using a timer, regardless
1268	# of whether the process is idle or not, and not letting	1796	# of whether the process is idle or not, and not letting
1269	# the callback use more than 50% of the time.	1797	# the callback use more than 50% of the time.
1270	sub idle {	1798	sub idle {
		1799	eval q{ # poor man's autoloading {}
		1800	*idle = sub {
1271	my (undef, %arg) = @_;	1801	my (undef, %arg) = @_;
1272		1802
1273	my ($cb, $w, $rcb) = $arg{cb};	1803	my ($cb, $w, $rcb) = $arg{cb};
1274		1804
1275	$rcb = sub {	1805	$rcb = sub {
1276	if ($cb) {	1806	if ($cb) {
1277	$w = _time;	1807	$w = AE::time;
1278	&$cb;	1808	&$cb;
1279	$w = _time - $w;	1809	$w = AE::time - $w;
1280		1810
1281	# never use more then 50% of the time for the idle watcher,	1811	# never use more then 50% of the time for the idle watcher,
1282	# within some limits	1812	# within some limits
1283	$w = 0.0001 if $w < 0.0001;	1813	$w = 0.0001 if $w < 0.0001;
1284	$w = 5 if $w > 5;	1814	$w = 5 if $w > 5;
1285		1815
1286	$w = AnyEvent->timer (after => $w, cb => $rcb);	1816	$w = AE::timer $w, 0, $rcb;
1287	} else {	1817	} else {
1288	# clean up...	1818	# clean up...
1289	undef $w;	1819	undef $w;
1290	undef $rcb;	1820	undef $rcb;
		1821	}
		1822	};
		1823
		1824	$w = AE::timer 0.05, 0, $rcb;
		1825
		1826	bless \\$cb, "AnyEvent::Base::idle"
1291	}	1827	};
		1828
		1829	*AnyEvent::Base::idle::DESTROY = sub {
		1830	undef $${$_[0]};
		1831	};
1292	};	1832	};
		1833	die if $@;
1293		1834
1294	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1835	&idle
1295
1296	bless \\$cb, "AnyEvent::Base::idle"
1297	}
1298
1299	sub AnyEvent::Base::idle::DESTROY {
1300	undef $${$_[0]};
1301	}	1836	}
1302		1837
1303	package AnyEvent::CondVar;	1838	package AnyEvent::CondVar;
1304		1839
1305	our @ISA = AnyEvent::CondVar::Base::;	1840	our @ISA = AnyEvent::CondVar::Base::;
1306		1841
		1842	# only to be used for subclassing
		1843	sub new {
		1844	my $class = shift;
		1845	bless AnyEvent->condvar (@_), $class
		1846	}
		1847
1307	package AnyEvent::CondVar::Base;	1848	package AnyEvent::CondVar::Base;
1308		1849
1309	use overload	1850	#use overload
1310	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1851	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1311	fallback => 1;	1852	# fallback => 1;
		1853
		1854	# save 300+ kilobytes by dirtily hardcoding overloading
		1855	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1856	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1857	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1858	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1859
		1860	our $WAITING;
1312		1861
1313	sub _send {	1862	sub _send {
1314	# nop	1863	# nop
		1864	}
		1865
		1866	sub _wait {
		1867	AnyEvent->_poll until $_[0]{_ae_sent};
1315	}	1868	}
1316		1869
1317	sub send {	1870	sub send {
1318	my $cv = shift;	1871	my $cv = shift;
1319	$cv->{_ae_sent} = [@_];	1872	$cv->{_ae_sent} = [@_];
…		…
1328		1881
1329	sub ready {	1882	sub ready {
1330	$_[0]{_ae_sent}	1883	$_[0]{_ae_sent}
1331	}	1884	}
1332		1885
1333	sub _wait {
1334	AnyEvent->one_event while !$_[0]{_ae_sent};
1335	}
1336
1337	sub recv {	1886	sub recv {
		1887	unless ($_[0]{_ae_sent}) {
		1888	$WAITING
		1889	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1890
		1891	local $WAITING = 1;
1338	$_[0]->_wait;	1892	$_[0]->_wait;
		1893	}
1339		1894
1340	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1895	$_[0]{_ae_croak}
1341	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1896	and Carp::croak $_[0]{_ae_croak};
		1897
		1898	wantarray
		1899	? @{ $_[0]{_ae_sent} }
		1900	: $_[0]{_ae_sent}[0]
1342	}	1901	}
1343		1902
1344	sub cb {	1903	sub cb {
1345	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1904	my $cv = shift;
		1905
		1906	@_
		1907	and $cv->{_ae_cb} = shift
		1908	and $cv->{_ae_sent}
		1909	and (delete $cv->{_ae_cb})->($cv);
		1910
1346	$_[0]{_ae_cb}	1911	$cv->{_ae_cb}
1347	}	1912	}
1348		1913
1349	sub begin {	1914	sub begin {
1350	++$_[0]{_ae_counter};	1915	++$_[0]{_ae_counter};
1351	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1916	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1356	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1921	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1357	}	1922	}
1358		1923
1359	# undocumented/compatibility with pre-3.4	1924	# undocumented/compatibility with pre-3.4
1360	*broadcast = \&send;	1925	*broadcast = \&send;
1361	*wait = \&_wait;	1926	*wait = \&recv;
1362		1927
1363	=head1 ERROR AND EXCEPTION HANDLING	1928	=head1 ERROR AND EXCEPTION HANDLING
1364		1929
1365	In general, AnyEvent does not do any error handling - it relies on the	1930	In general, AnyEvent does not do any error handling - it relies on the
1366	caller to do that if required. The L<AnyEvent::Strict> module (see also	1931	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1400	C<PERL_ANYEVENT_MODEL>.	1965	C<PERL_ANYEVENT_MODEL>.
1401		1966
1402	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1967	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1403	model it chooses.	1968	model it chooses.
1404		1969
		1970	When set to C<8> or higher, then AnyEvent will report extra information on
		1971	which optional modules it loads and how it implements certain features.
		1972
1405	=item C<PERL_ANYEVENT_STRICT>	1973	=item C<PERL_ANYEVENT_STRICT>
1406		1974
1407	AnyEvent does not do much argument checking by default, as thorough	1975	AnyEvent does not do much argument checking by default, as thorough
1408	argument checking is very costly. Setting this variable to a true value	1976	argument checking is very costly. Setting this variable to a true value
1409	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1977	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1410	check the arguments passed to most method calls. If it finds any problems,	1978	check the arguments passed to most method calls. If it finds any problems,
1411	it will croak.	1979	it will croak.
1412		1980
1413	In other words, enables "strict" mode.	1981	In other words, enables "strict" mode.
1414		1982
1415	Unlike C<use strict>, it is definitely recommended to keep it off in	1983	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1416	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1984	>>, it is definitely recommended to keep it off in production. Keeping
1417	developing programs can be very useful, however.	1985	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1986	can be very useful, however.
		1987
		1988	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1989
		1990	If this env variable is set, then its contents will be interpreted by
		1991	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		1992	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		1993	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		1994
		1995	This takes place when the first watcher is created.
		1996
		1997	For example, to bind a debug shell on a unix domain socket in
		1998	F<< /tmp/debug<pid>.sock >>, you could use this:
		1999
		2000	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug\$\$.sock perlprog
		2001
		2002	Note that creating sockets in F</tmp> is very unsafe on multiuser
		2003	systems.
		2004
		2005	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2006
		2007	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2008	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
1418		2009
1419	=item C<PERL_ANYEVENT_MODEL>	2010	=item C<PERL_ANYEVENT_MODEL>
1420		2011
1421	This can be used to specify the event model to be used by AnyEvent, before	2012	This can be used to specify the event model to be used by AnyEvent, before
1422	auto detection and -probing kicks in. It must be a string consisting	2013	auto detection and -probing kicks in.
1423	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	2014
		2015	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2016	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1424	and the resulting module name is loaded and if the load was successful,	2017	resulting module name is loaded and - if the load was successful - used as
1425	used as event model. If it fails to load AnyEvent will proceed with	2018	event model backend. If it fails to load then AnyEvent will proceed with
1426	auto detection and -probing.	2019	auto detection and -probing.
1427		2020
1428	This functionality might change in future versions.	2021	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2022	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2023	the end of a string designates a module name and quotes it appropriately).
1429		2024
1430	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	2025	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1431	could start your program like this:	2026	could start your program like this:
1432		2027
1433	PERL_ANYEVENT_MODEL=Perl perl ...	2028	PERL_ANYEVENT_MODEL=Perl perl ...
1434		2029
1435	=item C<PERL_ANYEVENT_PROTOCOLS>	2030	=item C<PERL_ANYEVENT_PROTOCOLS>
…		…
1484		2079
1485	When neither C<ca_file> nor C<ca_path> was specified during	2080	When neither C<ca_file> nor C<ca_path> was specified during
1486	L<AnyEvent::TLS> context creation, and either of these environment	2081	L<AnyEvent::TLS> context creation, and either of these environment
1487	variables exist, they will be used to specify CA certificate locations	2082	variables exist, they will be used to specify CA certificate locations
1488	instead of a system-dependent default.	2083	instead of a system-dependent default.
		2084
		2085	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2086
		2087	When these are set to C<1>, then the respective modules are not
		2088	loaded. Mostly good for testing AnyEvent itself.
1489		2089
1490	=back	2090	=back
1491		2091
1492	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2092	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1493		2093
…		…
1551	warn "read: $input\n"; # output what has been read	2151	warn "read: $input\n"; # output what has been read
1552	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2152	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1553	},	2153	},
1554	);	2154	);
1555		2155
1556	my $time_watcher; # can only be used once
1557
1558	sub new_timer {
1559	$timer = AnyEvent->timer (after => 1, cb => sub {	2156	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1560	warn "timeout\n"; # print 'timeout' about every second	2157	warn "timeout\n"; # print 'timeout' at most every second
1561	&new_timer; # and restart the time
1562	});	2158	});
1563	}
1564
1565	new_timer; # create first timer
1566		2159
1567	$cv->recv; # wait until user enters /^q/i	2160	$cv->recv; # wait until user enters /^q/i
1568		2161
1569	=head1 REAL-WORLD EXAMPLE	2162	=head1 REAL-WORLD EXAMPLE
1570		2163
…		…
1643		2236
1644	The actual code goes further and collects all errors (C<die>s, exceptions)	2237	The actual code goes further and collects all errors (C<die>s, exceptions)
1645	that occurred during request processing. The C<result> method detects	2238	that occurred during request processing. The C<result> method detects
1646	whether an exception as thrown (it is stored inside the $txn object)	2239	whether an exception as thrown (it is stored inside the $txn object)
1647	and just throws the exception, which means connection errors and other	2240	and just throws the exception, which means connection errors and other
1648	problems get reported tot he code that tries to use the result, not in a	2241	problems get reported to the code that tries to use the result, not in a
1649	random callback.	2242	random callback.
1650		2243
1651	All of this enables the following usage styles:	2244	All of this enables the following usage styles:
1652		2245
1653	1. Blocking:	2246	1. Blocking:
…		…
1701	through AnyEvent. The benchmark creates a lot of timers (with a zero	2294	through AnyEvent. The benchmark creates a lot of timers (with a zero
1702	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2295	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1703	which it is), lets them fire exactly once and destroys them again.	2296	which it is), lets them fire exactly once and destroys them again.
1704		2297
1705	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2298	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1706	distribution.	2299	distribution. It uses the L<AE> interface, which makes a real difference
		2300	for the EV and Perl backends only.
1707		2301
1708	=head3 Explanation of the columns	2302	=head3 Explanation of the columns
1709		2303
1710	I<watcher> is the number of event watchers created/destroyed. Since	2304	I<watcher> is the number of event watchers created/destroyed. Since
1711	different event models feature vastly different performances, each event	2305	different event models feature vastly different performances, each event
…		…
1732	watcher.	2326	watcher.
1733		2327
1734	=head3 Results	2328	=head3 Results
1735		2329
1736	name watchers bytes create invoke destroy comment	2330	name watchers bytes create invoke destroy comment
1737	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2331	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1738	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2332	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1739	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2333	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1740	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2334	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1741	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2335	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1742	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2336	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1743	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	2337	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1744	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	2338	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1745	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2339	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1746	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2340	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1747	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2341	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1748	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2342	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1749		2343
1750	=head3 Discussion	2344	=head3 Discussion
1751		2345
1752	The benchmark does I<not> measure scalability of the event loop very	2346	The benchmark does I<not> measure scalability of the event loop very
1753	well. For example, a select-based event loop (such as the pure perl one)	2347	well. For example, a select-based event loop (such as the pure perl one)
…		…
1765	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2359	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1766	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2360	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1767	cycles with POE.	2361	cycles with POE.
1768		2362
1769	C<EV> is the sole leader regarding speed and memory use, which are both	2363	C<EV> is the sole leader regarding speed and memory use, which are both
1770	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2364	maximal/minimal, respectively. When using the L<AE> API there is zero
		2365	overhead (when going through the AnyEvent API create is about 5-6 times
		2366	slower, with other times being equal, so still uses far less memory than
1771	far less memory than any other event loop and is still faster than Event	2367	any other event loop and is still faster than Event natively).
1772	natively.
1773		2368
1774	The pure perl implementation is hit in a few sweet spots (both the	2369	The pure perl implementation is hit in a few sweet spots (both the
1775	constant timeout and the use of a single fd hit optimisations in the perl	2370	constant timeout and the use of a single fd hit optimisations in the perl
1776	interpreter and the backend itself). Nevertheless this shows that it	2371	interpreter and the backend itself). Nevertheless this shows that it
1777	adds very little overhead in itself. Like any select-based backend its	2372	adds very little overhead in itself. Like any select-based backend its
…		…
1851	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2446	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1852	(1%) are active. This mirrors the activity of large servers with many	2447	(1%) are active. This mirrors the activity of large servers with many
1853	connections, most of which are idle at any one point in time.	2448	connections, most of which are idle at any one point in time.
1854		2449
1855	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2450	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1856	distribution.	2451	distribution. It uses the L<AE> interface, which makes a real difference
		2452	for the EV and Perl backends only.
1857		2453
1858	=head3 Explanation of the columns	2454	=head3 Explanation of the columns
1859		2455
1860	I<sockets> is the number of sockets, and twice the number of "servers" (as	2456	I<sockets> is the number of sockets, and twice the number of "servers" (as
1861	each server has a read and write socket end).	2457	each server has a read and write socket end).
…		…
1869	a new one that moves the timeout into the future.	2465	a new one that moves the timeout into the future.
1870		2466
1871	=head3 Results	2467	=head3 Results
1872		2468
1873	name sockets create request	2469	name sockets create request
1874	EV 20000 69.01 11.16	2470	EV 20000 62.66 7.99
1875	Perl 20000 73.32 35.87	2471	Perl 20000 68.32 32.64
1876	IOAsync 20000 157.00 98.14 epoll	2472	IOAsync 20000 174.06 101.15 epoll
1877	IOAsync 20000 159.31 616.06 poll	2473	IOAsync 20000 174.67 610.84 poll
1878	Event 20000 212.62 257.32	2474	Event 20000 202.69 242.91
1879	Glib 20000 651.16 1896.30	2475	Glib 20000 557.01 1689.52
1880	POE 20000 349.67 12317.24 uses POE::Loop::Event	2476	POE 20000 341.54 12086.32 uses POE::Loop::Event
1881		2477
1882	=head3 Discussion	2478	=head3 Discussion
1883		2479
1884	This benchmark I<does> measure scalability and overall performance of the	2480	This benchmark I<does> measure scalability and overall performance of the
1885	particular event loop.	2481	particular event loop.
…		…
2011	As you can see, the AnyEvent + EV combination even beats the	2607	As you can see, the AnyEvent + EV combination even beats the
2012	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2608	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2013	backend easily beats IO::Lambda and POE.	2609	backend easily beats IO::Lambda and POE.
2014		2610
2015	And even the 100% non-blocking version written using the high-level (and	2611	And even the 100% non-blocking version written using the high-level (and
2016	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a	2612	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2017	large margin, even though it does all of DNS, tcp-connect and socket I/O	2613	higher level ("unoptimised") abstractions by a large margin, even though
2018	in a non-blocking way.	2614	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2019		2615
2020	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2616	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2021	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are	2617	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2022	part of the IO::lambda distribution and were used without any changes.	2618	part of the IO::Lambda distribution and were used without any changes.
2023		2619
2024		2620
2025	=head1 SIGNALS	2621	=head1 SIGNALS
2026		2622
2027	AnyEvent currently installs handlers for these signals:	2623	AnyEvent currently installs handlers for these signals:
…		…
2032		2628
2033	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2629	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
2034	emulation for event loops that do not support them natively. Also, some	2630	emulation for event loops that do not support them natively. Also, some
2035	event loops install a similar handler.	2631	event loops install a similar handler.
2036		2632
2037	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will	2633	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
2038	reset it to default, to avoid losing child exit statuses.	2634	AnyEvent will reset it to default, to avoid losing child exit statuses.
2039		2635
2040	=item SIGPIPE	2636	=item SIGPIPE
2041		2637
2042	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2638	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
2043	when AnyEvent gets loaded.	2639	when AnyEvent gets loaded.
…		…
2061	if $SIG{CHLD} eq 'IGNORE';	2657	if $SIG{CHLD} eq 'IGNORE';
2062		2658
2063	$SIG{PIPE} = sub { }	2659	$SIG{PIPE} = sub { }
2064	unless defined $SIG{PIPE};	2660	unless defined $SIG{PIPE};
2065		2661
		2662	=head1 RECOMMENDED/OPTIONAL MODULES
		2663
		2664	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2665	its built-in modules) are required to use it.
		2666
		2667	That does not mean that AnyEvent won't take advantage of some additional
		2668	modules if they are installed.
		2669
		2670	This section explains which additional modules will be used, and how they
		2671	affect AnyEvent's operation.
		2672
		2673	=over 4
		2674
		2675	=item L<Async::Interrupt>
		2676
		2677	This slightly arcane module is used to implement fast signal handling: To
		2678	my knowledge, there is no way to do completely race-free and quick
		2679	signal handling in pure perl. To ensure that signals still get
		2680	delivered, AnyEvent will start an interval timer to wake up perl (and
		2681	catch the signals) with some delay (default is 10 seconds, look for
		2682	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2683
		2684	If this module is available, then it will be used to implement signal
		2685	catching, which means that signals will not be delayed, and the event loop
		2686	will not be interrupted regularly, which is more efficient (and good for
		2687	battery life on laptops).
		2688
		2689	This affects not just the pure-perl event loop, but also other event loops
		2690	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2691
		2692	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2693	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2694	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2695	does nothing for those backends.
		2696
		2697	=item L<EV>
		2698
		2699	This module isn't really "optional", as it is simply one of the backend
		2700	event loops that AnyEvent can use. However, it is simply the best event
		2701	loop available in terms of features, speed and stability: It supports
		2702	the AnyEvent API optimally, implements all the watcher types in XS, does
		2703	automatic timer adjustments even when no monotonic clock is available,
		2704	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2705	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2706	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2707
		2708	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2709	then this module will do nothing for you.
		2710
		2711	=item L<Guard>
		2712
		2713	The guard module, when used, will be used to implement
		2714	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2715	lot less memory), but otherwise doesn't affect guard operation much. It is
		2716	purely used for performance.
		2717
		2718	=item L<JSON> and L<JSON::XS>
		2719
		2720	One of these modules is required when you want to read or write JSON data
		2721	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2722	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2723
		2724	=item L<Net::SSLeay>
		2725
		2726	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2727	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2728	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2729
		2730	=item L<Time::HiRes>
		2731
		2732	This module is part of perl since release 5.008. It will be used when the
		2733	chosen event library does not come with a timing source of its own. The
		2734	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2735	try to use a monotonic clock for timing stability.
		2736
		2737	=back
		2738
		2739
2066	=head1 FORK	2740	=head1 FORK
2067		2741
2068	Most event libraries are not fork-safe. The ones who are usually are	2742	Most event libraries are not fork-safe. The ones who are usually are
2069	because they rely on inefficient but fork-safe C<select> or C<poll>	2743	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2070	calls. Only L<EV> is fully fork-aware.	2744	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2745	are usually badly thought-out hacks that are incompatible with fork in
		2746	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2747	continue event-processing in both parent and child (or both, if you know
		2748	what you are doing).
		2749
		2750	This means that, in general, you cannot fork and do event processing in
		2751	the child if the event library was initialised before the fork (which
		2752	usually happens when the first AnyEvent watcher is created, or the library
		2753	is loaded).
2071		2754
2072	If you have to fork, you must either do so I<before> creating your first	2755	If you have to fork, you must either do so I<before> creating your first
2073	watcher OR you must not use AnyEvent at all in the child.	2756	watcher OR you must not use AnyEvent at all in the child OR you must do
		2757	something completely out of the scope of AnyEvent.
		2758
		2759	The problem of doing event processing in the parent I<and> the child
		2760	is much more complicated: even for backends that I<are> fork-aware or
		2761	fork-safe, their behaviour is not usually what you want: fork clones all
		2762	watchers, that means all timers, I/O watchers etc. are active in both
		2763	parent and child, which is almost never what you want. USing C<exec>
		2764	to start worker children from some kind of manage rprocess is usually
		2765	preferred, because it is much easier and cleaner, at the expense of having
		2766	to have another binary.
2074		2767
2075		2768
2076	=head1 SECURITY CONSIDERATIONS	2769	=head1 SECURITY CONSIDERATIONS
2077		2770
2078	AnyEvent can be forced to load any event model via	2771	AnyEvent can be forced to load any event model via
…		…
2108	pronounced).	2801	pronounced).
2109		2802
2110		2803
2111	=head1 SEE ALSO	2804	=head1 SEE ALSO
2112		2805
		2806	Tutorial/Introduction: L<AnyEvent::Intro>.
		2807
		2808	FAQ: L<AnyEvent::FAQ>.
		2809
2113	Utility functions: L<AnyEvent::Util>.	2810	Utility functions: L<AnyEvent::Util>.
2114		2811
2115	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2812	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2116	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2813	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2117		2814
2118	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2815	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2119	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2816	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2120	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2817	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2121	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.	2818	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2122		2819
2123	Non-blocking file handles, sockets, TCP clients and	2820	Non-blocking file handles, sockets, TCP clients and
2124	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.	2821	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2125		2822
2126	Asynchronous DNS: L<AnyEvent::DNS>.	2823	Asynchronous DNS: L<AnyEvent::DNS>.
2127		2824
2128	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,	2825	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2129	L<Coro::Event>,
2130		2826
2131	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,	2827	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
2132	L<AnyEvent::HTTP>.	2828	L<AnyEvent::HTTP>.
2133		2829
2134		2830
2135	=head1 AUTHOR	2831	=head1 AUTHOR
2136		2832

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