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Revision 1.358 by root, Sat Aug 13 02:35:32 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	});
…		…
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
177		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		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> (I<not> file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
182	for events (AnyEvent might or might not keep a reference to this file	200	for events (AnyEvent might or might not keep a reference to this file
183	handle). Note that only file handles pointing to things for which	201	handle). Note that only file handles pointing to things for which
184	non-blocking operation makes sense are allowed. This includes sockets,	202	non-blocking operation makes sense are allowed. This includes sockets,
185	most character devices, pipes, fifos and so on, but not for example files	203	most character devices, pipes, fifos and so on, but not for example files
186	or block devices.	204	or block devices.
…		…
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
604	These two methods are EXPERIMENTAL and MIGHT CHANGE.
605		711
606	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
607	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
608	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
609		715
610	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
611	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
612	>>, 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
613	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
614	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.
615		722
616	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
617		730
618	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
619		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
620	my %result;	757	my %result;
621	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
622		759
623	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
624	$cv->begin;	761	$cv->begin;
625	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
626	$result{$host} = ...;	763	$result{$host} = ...;
…		…
641	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
642	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
643	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
644	doesn't execute once).	781	doesn't execute once).
645		782
646	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
647	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
648	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
649	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
650		788
651	=back	789	=back
652		790
653	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
654		792
…		…
658	=over 4	796	=over 4
659		797
660	=item $cv->recv	798	=item $cv->recv
661		799
662	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
663	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
664	normally.	802	normally.
665		803
666	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
667	will return immediately.	805	will return immediately.
668		806
…		…
670	function will call C<croak>.	808	function will call C<croak>.
671		809
672	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,
673	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
674		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
675	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
676	(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
677	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
678	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
679	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
680	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,
681	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
682		827
683	Another reason I<never> to C<< ->recv >> in a module is that you cannot
684	sensibly have two C<< ->recv >>'s in parallel, as that would require
685	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
686	can supply.
687
688	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
689	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
690	versions and also integrates coroutines into AnyEvent, making blocking
691	C<< ->recv >> calls perfectly safe as long as they are done from another
692	coroutine (one that doesn't run the event loop).
693
694	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
695	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
696	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
697	waits otherwise.	831	waits otherwise.
698		832
699	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
705		839
706	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
707	replaces it before doing so.	841	replaces it before doing so.
708		842
709	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
710	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
711	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
712	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.
713		848
714	=back	849	=back
715		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
716	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
717		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
718	=over 4	919	=over 4
719		920
720	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
721		922
722	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
723	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
724	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
725	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
726	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
727		930	will be C<urxvt::anyevent>).
728	The known classes so far are:
729
730	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
731	AnyEvent::Impl::Event based on Event, second best choice.
732	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
733	AnyEvent::Impl::Glib based on Glib, third-best choice.
734	AnyEvent::Impl::Tk based on Tk, very bad choice.
735	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
736	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
737	AnyEvent::Impl::POE based on POE, not generic enough for full support.
738
739	# warning, support for IO::Async is only partial, as it is too broken
740	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
741	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
742
743	There is no support for WxWidgets, as WxWidgets has no support for
744	watching file handles. However, you can use WxWidgets through the
745	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
746	second, which was considered to be too horrible to even consider for
747	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
748	it's adaptor.
749
750	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
751	autodetecting them.
752		931
753	=item AnyEvent::detect	932	=item AnyEvent::detect
754		933
755	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
756	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
757	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
758	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	If you need to do some initialisation before AnyEvent watchers are
		940	created, use C<post_detect>.
759		941
760	=item $guard = AnyEvent::post_detect { BLOCK }	942	=item $guard = AnyEvent::post_detect { BLOCK }
761		943
762	Arranges for the code block to be executed as soon as the event model is	944	Arranges for the code block to be executed as soon as the event model is
763	autodetected (or immediately if this has already happened).	945	autodetected (or immediately if that has already happened).
		946
		947	The block will be executed I<after> the actual backend has been detected
		948	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		949	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		950	other initialisations - see the sources of L<AnyEvent::Strict> or
		951	L<AnyEvent::AIO> to see how this is used.
		952
		953	The most common usage is to create some global watchers, without forcing
		954	event module detection too early, for example, L<AnyEvent::AIO> creates
		955	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		956	avoid autodetecting the event module at load time.
764		957
765	If called in scalar or list context, then it creates and returns an object	958	If called in scalar or list context, then it creates and returns an object
766	that automatically removes the callback again when it is destroyed. See	959	that automatically removes the callback again when it is destroyed (or
		960	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
767	L<Coro::BDB> for a case where this is useful.	961	a case where this is useful.
		962
		963	Example: Create a watcher for the IO::AIO module and store it in
		964	C<$WATCHER>, but do so only do so after the event loop is initialised.
		965
		966	our WATCHER;
		967
		968	my $guard = AnyEvent::post_detect {
		969	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		970	};
		971
		972	# the ||= is important in case post_detect immediately runs the block,
		973	# as to not clobber the newly-created watcher. assigning both watcher and
		974	# post_detect guard to the same variable has the advantage of users being
		975	# able to just C<undef $WATCHER> if the watcher causes them grief.
		976
		977	$WATCHER ||= $guard;
768		978
769	=item @AnyEvent::post_detect	979	=item @AnyEvent::post_detect
770		980
771	If there are any code references in this array (you can C<push> to it	981	If there are any code references in this array (you can C<push> to it
772	before or after loading AnyEvent), then they will called directly after	982	before or after loading AnyEvent), then they will be called directly
773	the event loop has been chosen.	983	after the event loop has been chosen.
774		984
775	You should check C<$AnyEvent::MODEL> before adding to this array, though:	985	You should check C<$AnyEvent::MODEL> before adding to this array, though:
776	if it contains a true value then the event loop has already been detected,	986	if it is defined then the event loop has already been detected, and the
777	and the array will be ignored.	987	array will be ignored.
778		988
779	Best use C<AnyEvent::post_detect { BLOCK }> instead.	989	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		990	it, as it takes care of these details.
		991
		992	This variable is mainly useful for modules that can do something useful
		993	when AnyEvent is used and thus want to know when it is initialised, but do
		994	not need to even load it by default. This array provides the means to hook
		995	into AnyEvent passively, without loading it.
		996
		997	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		998	together, you could put this into Coro (this is the actual code used by
		999	Coro to accomplish this):
		1000
		1001	if (defined $AnyEvent::MODEL) {
		1002	# AnyEvent already initialised, so load Coro::AnyEvent
		1003	require Coro::AnyEvent;
		1004	} else {
		1005	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1006	# as soon as it is
		1007	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1008	}
		1009
		1010	=item AnyEvent::postpone { BLOCK }
		1011
		1012	Arranges for the block to be executed as soon as possible, but not before
		1013	the call itself returns. In practise, the block will be executed just
		1014	before the event loop polls for new events, or shortly afterwards.
		1015
		1016	This function never returns anything (to make the C<return postpone { ...
		1017	}> idiom more useful.
		1018
		1019	To understand the usefulness of this function, consider a function that
		1020	asynchronously does something for you and returns some transaction
		1021	object or guard to let you cancel the operation. For example,
		1022	C<AnyEvent::Socket::tcp_connect>:
		1023
		1024	# start a conenction attempt unless one is active
		1025	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1026	delete $self->{connect_guard};
		1027	...
		1028	};
		1029
		1030	Imagine that this function could instantly call the callback, for
		1031	example, because it detects an obvious error such as a negative port
		1032	number. Invoking the callback before the function returns causes problems
		1033	however: the callback will be called and will try to delete the guard
		1034	object. But since the function hasn't returned yet, there is nothing to
		1035	delete. When the function eventually returns it will assign the guard
		1036	object to C<< $self->{connect_guard} >>, where it will likely never be
		1037	deleted, so the program thinks it is still trying to connect.
		1038
		1039	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1040	callback directly on error:
		1041
		1042	$cb->(undef), return # signal error to callback, BAD!
		1043	if $some_error_condition;
		1044
		1045	It should use C<postpone>:
		1046
		1047	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1048	if $some_error_condition;
780		1049
781	=back	1050	=back
782		1051
783	=head1 WHAT TO DO IN A MODULE	1052	=head1 WHAT TO DO IN A MODULE
784		1053
…		…
795	because it will stall the whole program, and the whole point of using	1064	because it will stall the whole program, and the whole point of using
796	events is to stay interactive.	1065	events is to stay interactive.
797		1066
798	It is fine, however, to call C<< ->recv >> when the user of your module	1067	It is fine, however, to call C<< ->recv >> when the user of your module
799	requests it (i.e. if you create a http request object ad have a method	1068	requests it (i.e. if you create a http request object ad have a method
800	called C<results> that returns the results, it should call C<< ->recv >>	1069	called C<results> that returns the results, it may call C<< ->recv >>
801	freely, as the user of your module knows what she is doing. always).	1070	freely, as the user of your module knows what she is doing. Always).
802		1071
803	=head1 WHAT TO DO IN THE MAIN PROGRAM	1072	=head1 WHAT TO DO IN THE MAIN PROGRAM
804		1073
805	There will always be a single main program - the only place that should	1074	There will always be a single main program - the only place that should
806	dictate which event model to use.	1075	dictate which event model to use.
807		1076
808	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1077	If the program is not event-based, it need not do anything special, even
809	do anything special (it does not need to be event-based) and let AnyEvent	1078	when it depends on a module that uses an AnyEvent. If the program itself
810	decide which implementation to chose if some module relies on it.	1079	uses AnyEvent, but does not care which event loop is used, all it needs
		1080	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1081	available loop implementation.
811		1082
812	If the main program relies on a specific event model - for example, in	1083	If the main program relies on a specific event model - for example, in
813	Gtk2 programs you have to rely on the Glib module - you should load the	1084	Gtk2 programs you have to rely on the Glib module - you should load the
814	event module before loading AnyEvent or any module that uses it: generally	1085	event module before loading AnyEvent or any module that uses it: generally
815	speaking, you should load it as early as possible. The reason is that	1086	speaking, you should load it as early as possible. The reason is that
816	modules might create watchers when they are loaded, and AnyEvent will	1087	modules might create watchers when they are loaded, and AnyEvent will
817	decide on the event model to use as soon as it creates watchers, and it	1088	decide on the event model to use as soon as it creates watchers, and it
818	might chose the wrong one unless you load the correct one yourself.	1089	might choose the wrong one unless you load the correct one yourself.
819		1090
820	You can chose to use a pure-perl implementation by loading the	1091	You can chose to use a pure-perl implementation by loading the
821	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1092	C<AnyEvent::Loop> module, which gives you similar behaviour
822	everywhere, but letting AnyEvent chose the model is generally better.	1093	everywhere, but letting AnyEvent chose the model is generally better.
823		1094
824	=head2 MAINLOOP EMULATION	1095	=head2 MAINLOOP EMULATION
825		1096
826	Sometimes (often for short test scripts, or even standalone programs who	1097	Sometimes (often for short test scripts, or even standalone programs who
…		…
839		1110
840		1111
841	=head1 OTHER MODULES	1112	=head1 OTHER MODULES
842		1113
843	The following is a non-exhaustive list of additional modules that use	1114	The following is a non-exhaustive list of additional modules that use
844	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1115	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
845	in the same program. Some of the modules come with AnyEvent, some are	1116	modules and other event loops in the same program. Some of the modules
846	available via CPAN.	1117	come as part of AnyEvent, the others are available via CPAN.
847		1118
848	=over 4	1119	=over 4
849		1120
850	=item L<AnyEvent::Util>	1121	=item L<AnyEvent::Util>
851		1122
852	Contains various utility functions that replace often-used but blocking	1123	Contains various utility functions that replace often-used blocking
853	functions such as C<inet_aton> by event-/callback-based versions.	1124	functions such as C<inet_aton> with event/callback-based versions.
854		1125
855	=item L<AnyEvent::Socket>	1126	=item L<AnyEvent::Socket>
856		1127
857	Provides various utility functions for (internet protocol) sockets,	1128	Provides various utility functions for (internet protocol) sockets,
858	addresses and name resolution. Also functions to create non-blocking tcp	1129	addresses and name resolution. Also functions to create non-blocking tcp
…		…
860		1131
861	=item L<AnyEvent::Handle>	1132	=item L<AnyEvent::Handle>
862		1133
863	Provide read and write buffers, manages watchers for reads and writes,	1134	Provide read and write buffers, manages watchers for reads and writes,
864	supports raw and formatted I/O, I/O queued and fully transparent and	1135	supports raw and formatted I/O, I/O queued and fully transparent and
865	non-blocking SSL/TLS.	1136	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
866		1137
867	=item L<AnyEvent::DNS>	1138	=item L<AnyEvent::DNS>
868		1139
869	Provides rich asynchronous DNS resolver capabilities.	1140	Provides rich asynchronous DNS resolver capabilities.
870		1141
		1142	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1143
		1144	Implement event-based interfaces to the protocols of the same name (for
		1145	the curious, IGS is the International Go Server and FCP is the Freenet
		1146	Client Protocol).
		1147
		1148	=item L<AnyEvent::Handle::UDP>
		1149
		1150	Here be danger!
		1151
		1152	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1153	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1154	its use of a stream-based API with a protocol that isn't streamable, that
		1155	the only way to improve it is to delete it.
		1156
		1157	It features data corruption (but typically only under load) and general
		1158	confusion. On top, the author is not only clueless about UDP but also
		1159	fact-resistant - some gems of his understanding: "connect doesn't work
		1160	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1161	packets", "I don't need to implement proper error checking as UDP doesn't
		1162	support error checking" and so on - he doesn't even understand what's
		1163	wrong with his module when it is explained to him.
		1164
871	=item L<AnyEvent::HTTP>	1165	=item L<AnyEvent::DBI>
872		1166
873	A simple-to-use HTTP library that is capable of making a lot of concurrent	1167	Executes L<DBI> requests asynchronously in a proxy process for you,
874	HTTP requests.	1168	notifying you in an event-based way when the operation is finished.
		1169
		1170	=item L<AnyEvent::AIO>
		1171
		1172	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1173	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1174	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1175	file I/O, and much more.
875		1176
876	=item L<AnyEvent::HTTPD>	1177	=item L<AnyEvent::HTTPD>
877		1178
878	Provides a simple web application server framework.	1179	A simple embedded webserver.
879		1180
880	=item L<AnyEvent::FastPing>	1181	=item L<AnyEvent::FastPing>
881		1182
882	The fastest ping in the west.	1183	The fastest ping in the west.
883		1184
884	=item L<AnyEvent::DBI>
885
886	Executes L<DBI> requests asynchronously in a proxy process.
887
888	=item L<AnyEvent::AIO>
889
890	Truly asynchronous I/O, should be in the toolbox of every event
891	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
892	together.
893
894	=item L<AnyEvent::BDB>
895
896	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
897	L<BDB> and AnyEvent together.
898
899	=item L<AnyEvent::GPSD>
900
901	A non-blocking interface to gpsd, a daemon delivering GPS information.
902
903	=item L<AnyEvent::IGS>
904
905	A non-blocking interface to the Internet Go Server protocol (used by
906	L<App::IGS>).
907
908	=item L<AnyEvent::IRC>
909
910	AnyEvent based IRC client module family (replacing the older Net::IRC3).
911
912	=item L<Net::XMPP2>
913
914	AnyEvent based XMPP (Jabber protocol) module family.
915
916	=item L<Net::FCP>
917
918	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
919	of AnyEvent.
920
921	=item L<Event::ExecFlow>
922
923	High level API for event-based execution flow control.
924
925	=item L<Coro>	1185	=item L<Coro>
926		1186
927	Has special support for AnyEvent via L<Coro::AnyEvent>.	1187	Has special support for AnyEvent via L<Coro::AnyEvent>.
928		1188
929	=item L<IO::Lambda>
930
931	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
932
933	=back	1189	=back
934		1190
935	=cut	1191	=cut
936		1192
937	package AnyEvent;	1193	package AnyEvent;
938		1194
939	no warnings;	1195	# basically a tuned-down version of common::sense
940	use strict qw(vars subs);	1196	sub common_sense {
		1197	# from common:.sense 3.4
		1198	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1199	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1200	$^H |= 0x00000600;
		1201	}
941		1202
		1203	BEGIN { AnyEvent::common_sense }
		1204
942	use Carp;	1205	use Carp ();
943		1206
944	our $VERSION = 4.412;	1207	our $VERSION = '5.34';
945	our $MODEL;	1208	our $MODEL;
946		1209
947	our $AUTOLOAD;
948	our @ISA;	1210	our @ISA;
949		1211
950	our @REGISTRY;	1212	our @REGISTRY;
951		1213
952	our $WIN32;	1214	our $VERBOSE;
953		1215
954	BEGIN {	1216	BEGIN {
955	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1217	require "AnyEvent/constants.pl";
		1218
956	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1219	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
957		1220
958	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1221	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
959	if ${^TAINT};	1222	if ${^TAINT};
960	}
961		1223
962	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1224	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1225
		1226	}
		1227
		1228	our $MAX_SIGNAL_LATENCY = 10;
963		1229
964	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1230	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
965		1231
966	{	1232	{
967	my $idx;	1233	my $idx;
968	$PROTOCOL{$_} = ++$idx	1234	$PROTOCOL{$_} = ++$idx
969	for reverse split /\s*,\s*/,	1235	for reverse split /\s*,\s*/,
970	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1236	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
971	}	1237	}
972		1238
		1239	our @post_detect;
		1240
		1241	sub post_detect(&) {
		1242	my ($cb) = @_;
		1243
		1244	push @post_detect, $cb;
		1245
		1246	defined wantarray
		1247	? bless \$cb, "AnyEvent::Util::postdetect"
		1248	: ()
		1249	}
		1250
		1251	sub AnyEvent::Util::postdetect::DESTROY {
		1252	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1253	}
		1254
		1255	our $POSTPONE_W;
		1256	our @POSTPONE;
		1257
		1258	sub _postpone_exec {
		1259	undef $POSTPONE_W;
		1260
		1261	&{ shift @POSTPONE }
		1262	while @POSTPONE;
		1263	}
		1264
		1265	sub postpone(&) {
		1266	push @POSTPONE, shift;
		1267
		1268	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1269
		1270	()
		1271	}
		1272
973	my @models = (	1273	our @models = (
974	[EV:: => AnyEvent::Impl::EV::],	1274	[EV:: => AnyEvent::Impl::EV:: , 1],
975	[Event:: => AnyEvent::Impl::Event::],	1275	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
976	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
977	# everything below here will not be autoprobed	1276	# everything below here will not (normally) be autoprobed
978	# as the pureperl backend should work everywhere	1277	# as the pure perl backend should work everywhere
979	# and is usually faster	1278	# and is usually faster
		1279	[Event:: => AnyEvent::Impl::Event::, 1],
		1280	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1281	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1282	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
980	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1283	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
981	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
982	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
983	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1284	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
984	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1285	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
985	[Wx:: => AnyEvent::Impl::POE::],	1286	[Wx:: => AnyEvent::Impl::POE::],
986	[Prima:: => AnyEvent::Impl::POE::],	1287	[Prima:: => AnyEvent::Impl::POE::],
987	# IO::Async is just too broken - we would need workaorunds for its	1288	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
988	# byzantine signal and broken child handling, among others.	1289	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
989	# IO::Async is rather hard to detect, as it doesn't have any	1290	[FLTK:: => AnyEvent::Impl::FLTK2::],
990	# obvious default class.
991	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
992	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
993	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
994	);	1291	);
995		1292
996	our %method = map +($_ => 1),	1293	# all autoloaded methods reserve the complete glob, not just the method slot.
		1294	# due to bugs in perls method cache implementation.
997	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1295	our @methods = qw(io timer time now now_update signal child idle condvar);
998		1296
999	our @post_detect;
1000
1001	sub post_detect(&) {	1297	sub detect() {
1002	my ($cb) = @_;	1298	local $!; # for good measure
		1299	local $SIG{__DIE__}; # we use eval
1003		1300
1004	if ($MODEL) {	1301	# free some memory
1005	$cb->();	1302	*detect = sub () { $MODEL };
		1303	# undef &func doesn't correctly update the method cache. grmbl.
		1304	# so we delete the whole glob. grmbl.
		1305	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1306	# a glob with an active sub. hrm. i hope it works, but perl is
		1307	# usually buggy in this department. sigh.
		1308	delete @{"AnyEvent::"}{@methods};
		1309	undef @methods;
1006		1310
1007	1	1311	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1312	my $model = $1;
		1313	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1314	if (eval "require $model") {
		1315	$MODEL = $model;
		1316	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1008	} else {	1317	} else {
1009	push @post_detect, $cb;	1318	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1010		1319	}
1011	defined wantarray
1012	? bless \$cb, "AnyEvent::Util::postdetect"
1013	: ()
1014	}	1320	}
1015	}
1016		1321
1017	sub AnyEvent::Util::postdetect::DESTROY {	1322	# check for already loaded models
1018	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1019	}
1020
1021	sub detect() {
1022	unless ($MODEL) {	1323	unless ($MODEL) {
1023	no strict 'refs';	1324	for (@REGISTRY, @models) {
1024	local $SIG{__DIE__};	1325	my ($package, $model) = @$_;
1025		1326	if (${"$package\::VERSION"} > 0) {
1026	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1027	my $model = "AnyEvent::Impl::$1";
1028	if (eval "require $model") {	1327	if (eval "require $model") {
1029	$MODEL = $model;	1328	$MODEL = $model;
1030	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1329	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1031	} else {	1330	last;
1032	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1331	}
1033	}	1332	}
1034	}	1333	}
1035		1334
1036	# check for already loaded models
1037	unless ($MODEL) {	1335	unless ($MODEL) {
		1336	# try to autoload a model
1038	for (@REGISTRY, @models) {	1337	for (@REGISTRY, @models) {
1039	my ($package, $model) = @$_;	1338	my ($package, $model, $autoload) = @$_;
		1339	if (
		1340	$autoload
		1341	and eval "require $package"
1040	if (${"$package\::VERSION"} > 0) {	1342	and ${"$package\::VERSION"} > 0
1041	if (eval "require $model") {	1343	and eval "require $model"
		1344	) {
1042	$MODEL = $model;	1345	$MODEL = $model;
1043	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1346	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1044	last;	1347	last;
1045	}
1046	}	1348	}
1047	}	1349	}
1048		1350
1049	unless ($MODEL) {
1050	# try to load a model
1051
1052	for (@REGISTRY, @models) {
1053	my ($package, $model) = @$_;
1054	if (eval "require $package"
1055	and ${"$package\::VERSION"} > 0
1056	and eval "require $model") {
1057	$MODEL = $model;
1058	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1059	last;
1060	}
1061	}
1062
1063	$MODEL	1351	$MODEL
1064	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1352	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1065	}
1066	}	1353	}
1067
1068	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1069
1070	unshift @ISA, $MODEL;
1071
1072	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1073
1074	(shift @post_detect)->() while @post_detect;
1075	}	1354	}
1076		1355
		1356	# free memory only needed for probing
		1357	undef @models;
		1358	undef @REGISTRY;
		1359
		1360	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1361	unshift @ISA, $MODEL;
		1362
		1363	# now nuke some methods that are overridden by the backend.
		1364	# SUPER usage is not allowed in these.
		1365	for (qw(time signal child idle)) {
		1366	undef &{"AnyEvent::Base::$_"}
		1367	if defined &{"$MODEL\::$_"};
		1368	}
		1369
		1370	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1371	require AnyEvent::Strict;
		1372	}
		1373
		1374	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1375	require AnyEvent::Debug;
		1376	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1377	}
		1378
		1379	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1380	require AnyEvent::Socket;
		1381	require AnyEvent::Debug;
		1382
		1383	my ($host, $service) = AnyEvent::Socket::parse_hostport ($ENV{PERL_ANYEVENT_DEBUG_SHELL});
		1384	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1385	}
		1386
		1387	(shift @post_detect)->() while @post_detect;
		1388	undef @post_detect;
		1389
		1390	*post_detect = sub(&) {
		1391	shift->();
		1392
		1393	undef
		1394	};
		1395
1077	$MODEL	1396	$MODEL
1078	}	1397	}
1079		1398
1080	sub AUTOLOAD {	1399	for my $name (@methods) {
1081	(my $func = $AUTOLOAD) =~ s/.*://;	1400	*$name = sub {
1082		1401	detect;
1083	$method{$func}	1402	# we use goto because
1084	or croak "$func: not a valid method for AnyEvent objects";	1403	# a) it makes the thunk more transparent
1085		1404	# b) it allows us to delete the thunk later
1086	detect unless $MODEL;	1405	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
1087		1406	};
1088	my $class = shift;
1089	$class->$func (@_);
1090	}	1407	}
1091		1408
1092	# utility function to dup a filehandle. this is used by many backends	1409	# utility function to dup a filehandle. this is used by many backends
1093	# to support binding more than one watcher per filehandle (they usually	1410	# to support binding more than one watcher per filehandle (they usually
1094	# allow only one watcher per fd, so we dup it to get a different one).	1411	# allow only one watcher per fd, so we dup it to get a different one).
1095	sub _dupfh($$;$$) {	1412	sub _dupfh($$;$$) {
1096	my ($poll, $fh, $r, $w) = @_;	1413	my ($poll, $fh, $r, $w) = @_;
1097		1414
1098	# cygwin requires the fh mode to be matching, unix doesn't	1415	# cygwin requires the fh mode to be matching, unix doesn't
1099	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1416	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1100	: $poll eq "w" ? ($w, ">")
1101	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1102		1417
1103	open my $fh2, "$mode&" . fileno $fh	1418	open my $fh2, $mode, $fh
1104	or die "cannot dup() filehandle: $!,";	1419	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1105		1420
1106	# we assume CLOEXEC is already set by perl in all important cases	1421	# we assume CLOEXEC is already set by perl in all important cases
1107		1422
1108	($fh2, $rw)	1423	($fh2, $rw)
1109	}	1424	}
1110		1425
		1426	=head1 SIMPLIFIED AE API
		1427
		1428	Starting with version 5.0, AnyEvent officially supports a second, much
		1429	simpler, API that is designed to reduce the calling, typing and memory
		1430	overhead by using function call syntax and a fixed number of parameters.
		1431
		1432	See the L<AE> manpage for details.
		1433
		1434	=cut
		1435
		1436	package AE;
		1437
		1438	our $VERSION = $AnyEvent::VERSION;
		1439
		1440	sub _reset() {
		1441	eval q{
		1442	# fall back to the main API by default - backends and AnyEvent::Base
		1443	# implementations can overwrite these.
		1444
		1445	sub io($$$) {
		1446	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1447	}
		1448
		1449	sub timer($$$) {
		1450	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1451	}
		1452
		1453	sub signal($$) {
		1454	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1455	}
		1456
		1457	sub child($$) {
		1458	AnyEvent->child (pid => $_[0], cb => $_[1])
		1459	}
		1460
		1461	sub idle($) {
		1462	AnyEvent->idle (cb => $_[0]);
		1463	}
		1464
		1465	sub cv(;&) {
		1466	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1467	}
		1468
		1469	sub now() {
		1470	AnyEvent->now
		1471	}
		1472
		1473	sub now_update() {
		1474	AnyEvent->now_update
		1475	}
		1476
		1477	sub time() {
		1478	AnyEvent->time
		1479	}
		1480
		1481	*postpone = \&AnyEvent::postpone;
		1482	};
		1483	die if $@;
		1484	}
		1485
		1486	BEGIN { _reset }
		1487
1111	package AnyEvent::Base;	1488	package AnyEvent::Base;
1112		1489
1113	# default implementations for many methods	1490	# default implementations for many methods
1114		1491
1115	BEGIN {	1492	sub time {
		1493	eval q{ # poor man's autoloading {}
		1494	# probe for availability of Time::HiRes
1116	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1495	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1496	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1117	*_time = \&Time::HiRes::time;	1497	*AE::time = \&Time::HiRes::time;
1118	# if (eval "use POSIX (); (POSIX::times())...	1498	# if (eval "use POSIX (); (POSIX::times())...
1119	} else {	1499	} else {
		1500	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1120	*_time = sub { time }; # epic fail	1501	*AE::time = sub (){ time }; # epic fail
		1502	}
		1503
		1504	*time = sub { AE::time }; # different prototypes
		1505	};
		1506	die if $@;
		1507
		1508	&time
		1509	}
		1510
		1511	*now = \&time;
		1512
		1513	sub now_update { }
		1514
		1515	sub _poll {
		1516	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1517	}
		1518
		1519	# default implementation for ->condvar
		1520	# in fact, the default should not be overwritten
		1521
		1522	sub condvar {
		1523	eval q{ # poor man's autoloading {}
		1524	*condvar = sub {
		1525	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1526	};
		1527
		1528	*AE::cv = sub (;&) {
		1529	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1530	};
		1531	};
		1532	die if $@;
		1533
		1534	&condvar
		1535	}
		1536
		1537	# default implementation for ->signal
		1538
		1539	our $HAVE_ASYNC_INTERRUPT;
		1540
		1541	sub _have_async_interrupt() {
		1542	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1543	&& eval "use Async::Interrupt 1.02 (); 1")
		1544	unless defined $HAVE_ASYNC_INTERRUPT;
		1545
		1546	$HAVE_ASYNC_INTERRUPT
		1547	}
		1548
		1549	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1550	our (%SIG_ASY, %SIG_ASY_W);
		1551	our ($SIG_COUNT, $SIG_TW);
		1552
		1553	# install a dummy wakeup watcher to reduce signal catching latency
		1554	# used by Impls
		1555	sub _sig_add() {
		1556	unless ($SIG_COUNT++) {
		1557	# try to align timer on a full-second boundary, if possible
		1558	my $NOW = AE::now;
		1559
		1560	$SIG_TW = AE::timer
		1561	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1562	$MAX_SIGNAL_LATENCY,
		1563	sub { } # just for the PERL_ASYNC_CHECK
		1564	;
1121	}	1565	}
1122	}	1566	}
1123		1567
1124	sub time { _time }	1568	sub _sig_del {
1125	sub now { _time }	1569	undef $SIG_TW
1126	sub now_update { }	1570	unless --$SIG_COUNT;
1127
1128	# default implementation for ->condvar
1129
1130	sub condvar {
1131	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1132	}	1571	}
1133		1572
1134	# default implementation for ->signal	1573	our $_sig_name_init; $_sig_name_init = sub {
		1574	eval q{ # poor man's autoloading {}
		1575	undef $_sig_name_init;
1135		1576
1136	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1577	if (_have_async_interrupt) {
		1578	*sig2num = \&Async::Interrupt::sig2num;
		1579	*sig2name = \&Async::Interrupt::sig2name;
		1580	} else {
		1581	require Config;
1137		1582
1138	sub _signal_exec {	1583	my %signame2num;
1139	sysread $SIGPIPE_R, my $dummy, 4;	1584	@signame2num{ split ' ', $Config::Config{sig_name} }
		1585	= split ' ', $Config::Config{sig_num};
1140		1586
1141	while (%SIG_EV) {	1587	my @signum2name;
1142	for (keys %SIG_EV) {	1588	@signum2name[values %signame2num] = keys %signame2num;
1143	delete $SIG_EV{$_};	1589
1144	$_->() for values %{ $SIG_CB{$_} || {} };	1590	*sig2num = sub($) {
		1591	$_[0] > 0 ? shift : $signame2num{+shift}
		1592	};
		1593	*sig2name = sub ($) {
		1594	$_[0] > 0 ? $signum2name[+shift] : shift
		1595	};
1145	}	1596	}
1146	}	1597	};
1147	}	1598	die if $@;
		1599	};
		1600
		1601	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1602	sub sig2name($) { &$_sig_name_init; &sig2name }
1148		1603
1149	sub signal {	1604	sub signal {
1150	my (undef, %arg) = @_;	1605	eval q{ # poor man's autoloading {}
		1606	# probe for availability of Async::Interrupt
		1607	if (_have_async_interrupt) {
		1608	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1151		1609
1152	unless ($SIGPIPE_R) {	1610	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1153	require Fcntl;	1611	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1154		1612
1155	if (AnyEvent::WIN32) {
1156	require AnyEvent::Util;
1157
1158	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1159	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1160	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1161	} else {	1613	} else {
		1614	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1615
		1616	if (AnyEvent::WIN32) {
		1617	require AnyEvent::Util;
		1618
		1619	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1620	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1621	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1622	} else {
1162	pipe $SIGPIPE_R, $SIGPIPE_W;	1623	pipe $SIGPIPE_R, $SIGPIPE_W;
1163	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1624	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1164	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1625	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1165		1626
1166	# not strictly required, as $^F is normally 2, but let's make sure...	1627	# not strictly required, as $^F is normally 2, but let's make sure...
1167	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1628	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1168	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1629	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1630	}
		1631
		1632	$SIGPIPE_R
		1633	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1634
		1635	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1169	}	1636	}
1170		1637
1171	$SIGPIPE_R	1638	*signal = $HAVE_ASYNC_INTERRUPT
1172	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1639	? sub {
		1640	my (undef, %arg) = @_;
1173		1641
1174	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1642	# async::interrupt
1175	}
1176
1177	my $signal = uc $arg{signal}	1643	my $signal = sig2num $arg{signal};
1178	or Carp::croak "required option 'signal' is missing";
1179
1180	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1644	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1645
		1646	$SIG_ASY{$signal} ||= new Async::Interrupt
		1647	cb => sub { undef $SIG_EV{$signal} },
		1648	signal => $signal,
		1649	pipe => [$SIGPIPE_R->filenos],
		1650	pipe_autodrain => 0,
		1651	;
		1652
		1653	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1654	}
		1655	: sub {
		1656	my (undef, %arg) = @_;
		1657
		1658	# pure perl
		1659	my $signal = sig2name $arg{signal};
		1660	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1661
1181	$SIG{$signal} ||= sub {	1662	$SIG{$signal} ||= sub {
1182	local $!;	1663	local $!;
1183	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1664	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1184	undef $SIG_EV{$signal};	1665	undef $SIG_EV{$signal};
		1666	};
		1667
		1668	# can't do signal processing without introducing races in pure perl,
		1669	# so limit the signal latency.
		1670	_sig_add;
		1671
		1672	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1673	}
		1674	;
		1675
		1676	*AnyEvent::Base::signal::DESTROY = sub {
		1677	my ($signal, $cb) = @{$_[0]};
		1678
		1679	_sig_del;
		1680
		1681	delete $SIG_CB{$signal}{$cb};
		1682
		1683	$HAVE_ASYNC_INTERRUPT
		1684	? delete $SIG_ASY{$signal}
		1685	: # delete doesn't work with older perls - they then
		1686	# print weird messages, or just unconditionally exit
		1687	# instead of getting the default action.
		1688	undef $SIG{$signal}
		1689	unless keys %{ $SIG_CB{$signal} };
		1690	};
		1691
		1692	*_signal_exec = sub {
		1693	$HAVE_ASYNC_INTERRUPT
		1694	? $SIGPIPE_R->drain
		1695	: sysread $SIGPIPE_R, (my $dummy), 9;
		1696
		1697	while (%SIG_EV) {
		1698	for (keys %SIG_EV) {
		1699	delete $SIG_EV{$_};
		1700	&$_ for values %{ $SIG_CB{$_} || {} };
		1701	}
		1702	}
		1703	};
1185	};	1704	};
		1705	die if $@;
1186		1706
1187	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1707	&signal
1188	}
1189
1190	sub AnyEvent::Base::signal::DESTROY {
1191	my ($signal, $cb) = @{$_[0]};
1192
1193	delete $SIG_CB{$signal}{$cb};
1194
1195	# delete doesn't work with older perls - they then
1196	# print weird messages, or just unconditionally exit
1197	# instead of getting the default action.
1198	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1199	}	1708	}
1200		1709
1201	# default implementation for ->child	1710	# default implementation for ->child
1202		1711
1203	our %PID_CB;	1712	our %PID_CB;
1204	our $CHLD_W;	1713	our $CHLD_W;
1205	our $CHLD_DELAY_W;	1714	our $CHLD_DELAY_W;
1206	our $WNOHANG;
1207		1715
1208	sub _sigchld {	1716	# used by many Impl's
1209	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1717	sub _emit_childstatus($$) {
		1718	my (undef, $rpid, $rstatus) = @_;
		1719
		1720	$_->($rpid, $rstatus)
1210	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1721	for values %{ $PID_CB{$rpid} || {} },
1211	(values %{ $PID_CB{0} || {} });	1722	values %{ $PID_CB{0} || {} };
1212	}
1213	}	1723	}
1214		1724
1215	sub child {	1725	sub child {
		1726	eval q{ # poor man's autoloading {}
		1727	*_sigchld = sub {
		1728	my $pid;
		1729
		1730	AnyEvent->_emit_childstatus ($pid, $?)
		1731	while ($pid = waitpid -1, WNOHANG) > 0;
		1732	};
		1733
		1734	*child = sub {
1216	my (undef, %arg) = @_;	1735	my (undef, %arg) = @_;
1217		1736
1218	defined (my $pid = $arg{pid} + 0)	1737	my $pid = $arg{pid};
1219	or Carp::croak "required option 'pid' is missing";	1738	my $cb = $arg{cb};
1220		1739
1221	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1740	$PID_CB{$pid}{$cb+0} = $cb;
1222		1741
1223	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1224
1225	unless ($CHLD_W) {	1742	unless ($CHLD_W) {
1226	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1743	$CHLD_W = AE::signal CHLD => \&_sigchld;
1227	# child could be a zombie already, so make at least one round	1744	# child could be a zombie already, so make at least one round
1228	&_sigchld;	1745	&_sigchld;
1229	}	1746	}
1230		1747
1231	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1748	bless [$pid, $cb+0], "AnyEvent::Base::child"
1232	}	1749	};
1233		1750
1234	sub AnyEvent::Base::child::DESTROY {	1751	*AnyEvent::Base::child::DESTROY = sub {
1235	my ($pid, $cb) = @{$_[0]};	1752	my ($pid, $icb) = @{$_[0]};
1236		1753
1237	delete $PID_CB{$pid}{$cb};	1754	delete $PID_CB{$pid}{$icb};
1238	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1755	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1239		1756
1240	undef $CHLD_W unless keys %PID_CB;	1757	undef $CHLD_W unless keys %PID_CB;
		1758	};
		1759	};
		1760	die if $@;
		1761
		1762	&child
1241	}	1763	}
1242		1764
1243	# idle emulation is done by simply using a timer, regardless	1765	# idle emulation is done by simply using a timer, regardless
1244	# of whether the process is idle or not, and not letting	1766	# of whether the process is idle or not, and not letting
1245	# the callback use more than 50% of the time.	1767	# the callback use more than 50% of the time.
1246	sub idle {	1768	sub idle {
		1769	eval q{ # poor man's autoloading {}
		1770	*idle = sub {
1247	my (undef, %arg) = @_;	1771	my (undef, %arg) = @_;
1248		1772
1249	my ($cb, $w, $rcb) = $arg{cb};	1773	my ($cb, $w, $rcb) = $arg{cb};
1250		1774
1251	$rcb = sub {	1775	$rcb = sub {
1252	if ($cb) {	1776	if ($cb) {
1253	$w = _time;	1777	$w = AE::time;
1254	&$cb;	1778	&$cb;
1255	$w = _time - $w;	1779	$w = AE::time - $w;
1256		1780
1257	# never use more then 50% of the time for the idle watcher,	1781	# never use more then 50% of the time for the idle watcher,
1258	# within some limits	1782	# within some limits
1259	$w = 0.0001 if $w < 0.0001;	1783	$w = 0.0001 if $w < 0.0001;
1260	$w = 5 if $w > 5;	1784	$w = 5 if $w > 5;
1261		1785
1262	$w = AnyEvent->timer (after => $w, cb => $rcb);	1786	$w = AE::timer $w, 0, $rcb;
1263	} else {	1787	} else {
1264	# clean up...	1788	# clean up...
1265	undef $w;	1789	undef $w;
1266	undef $rcb;	1790	undef $rcb;
		1791	}
		1792	};
		1793
		1794	$w = AE::timer 0.05, 0, $rcb;
		1795
		1796	bless \\$cb, "AnyEvent::Base::idle"
1267	}	1797	};
		1798
		1799	*AnyEvent::Base::idle::DESTROY = sub {
		1800	undef $${$_[0]};
		1801	};
1268	};	1802	};
		1803	die if $@;
1269		1804
1270	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1805	&idle
1271
1272	bless \\$cb, "AnyEvent::Base::idle"
1273	}
1274
1275	sub AnyEvent::Base::idle::DESTROY {
1276	undef $${$_[0]};
1277	}	1806	}
1278		1807
1279	package AnyEvent::CondVar;	1808	package AnyEvent::CondVar;
1280		1809
1281	our @ISA = AnyEvent::CondVar::Base::;	1810	our @ISA = AnyEvent::CondVar::Base::;
1282		1811
		1812	# only to be used for subclassing
		1813	sub new {
		1814	my $class = shift;
		1815	bless AnyEvent->condvar (@_), $class
		1816	}
		1817
1283	package AnyEvent::CondVar::Base;	1818	package AnyEvent::CondVar::Base;
1284		1819
1285	use overload	1820	#use overload
1286	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1821	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1287	fallback => 1;	1822	# fallback => 1;
		1823
		1824	# save 300+ kilobytes by dirtily hardcoding overloading
		1825	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1826	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1827	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1828	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1829
		1830	our $WAITING;
1288		1831
1289	sub _send {	1832	sub _send {
1290	# nop	1833	# nop
		1834	}
		1835
		1836	sub _wait {
		1837	AnyEvent->_poll until $_[0]{_ae_sent};
1291	}	1838	}
1292		1839
1293	sub send {	1840	sub send {
1294	my $cv = shift;	1841	my $cv = shift;
1295	$cv->{_ae_sent} = [@_];	1842	$cv->{_ae_sent} = [@_];
…		…
1304		1851
1305	sub ready {	1852	sub ready {
1306	$_[0]{_ae_sent}	1853	$_[0]{_ae_sent}
1307	}	1854	}
1308		1855
1309	sub _wait {
1310	AnyEvent->one_event while !$_[0]{_ae_sent};
1311	}
1312
1313	sub recv {	1856	sub recv {
		1857	unless ($_[0]{_ae_sent}) {
		1858	$WAITING
		1859	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1860
		1861	local $WAITING = 1;
1314	$_[0]->_wait;	1862	$_[0]->_wait;
		1863	}
1315		1864
1316	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1865	$_[0]{_ae_croak}
1317	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1866	and Carp::croak $_[0]{_ae_croak};
		1867
		1868	wantarray
		1869	? @{ $_[0]{_ae_sent} }
		1870	: $_[0]{_ae_sent}[0]
1318	}	1871	}
1319		1872
1320	sub cb {	1873	sub cb {
1321	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1874	my $cv = shift;
		1875
		1876	@_
		1877	and $cv->{_ae_cb} = shift
		1878	and $cv->{_ae_sent}
		1879	and (delete $cv->{_ae_cb})->($cv);
		1880
1322	$_[0]{_ae_cb}	1881	$cv->{_ae_cb}
1323	}	1882	}
1324		1883
1325	sub begin {	1884	sub begin {
1326	++$_[0]{_ae_counter};	1885	++$_[0]{_ae_counter};
1327	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1886	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1332	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1891	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1333	}	1892	}
1334		1893
1335	# undocumented/compatibility with pre-3.4	1894	# undocumented/compatibility with pre-3.4
1336	*broadcast = \&send;	1895	*broadcast = \&send;
1337	*wait = \&_wait;	1896	*wait = \&recv;
1338		1897
1339	=head1 ERROR AND EXCEPTION HANDLING	1898	=head1 ERROR AND EXCEPTION HANDLING
1340		1899
1341	In general, AnyEvent does not do any error handling - it relies on the	1900	In general, AnyEvent does not do any error handling - it relies on the
1342	caller to do that if required. The L<AnyEvent::Strict> module (see also	1901	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1376	C<PERL_ANYEVENT_MODEL>.	1935	C<PERL_ANYEVENT_MODEL>.
1377		1936
1378	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1937	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1379	model it chooses.	1938	model it chooses.
1380		1939
		1940	When set to C<8> or higher, then AnyEvent will report extra information on
		1941	which optional modules it loads and how it implements certain features.
		1942
1381	=item C<PERL_ANYEVENT_STRICT>	1943	=item C<PERL_ANYEVENT_STRICT>
1382		1944
1383	AnyEvent does not do much argument checking by default, as thorough	1945	AnyEvent does not do much argument checking by default, as thorough
1384	argument checking is very costly. Setting this variable to a true value	1946	argument checking is very costly. Setting this variable to a true value
1385	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1947	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1386	check the arguments passed to most method calls. If it finds any problems,	1948	check the arguments passed to most method calls. If it finds any problems,
1387	it will croak.	1949	it will croak.
1388		1950
1389	In other words, enables "strict" mode.	1951	In other words, enables "strict" mode.
1390		1952
1391	Unlike C<use strict>, it is definitely recommended to keep it off in	1953	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1392	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1954	>>, it is definitely recommended to keep it off in production. Keeping
1393	developing programs can be very useful, however.	1955	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1956	can be very useful, however.
		1957
		1958	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1959
		1960	If this env variable is set, then its contents will be
		1961	interpreted by C<AnyEvent::Socket::parse_hostport> and an
		1962	C<AnyEvent::Debug::shell> is bound on that port. The shell object is saved
		1963	in C<$AnyEvent::Debug::SHELL>.
		1964
		1965	For example, to bind a debug shell on a unix domain socket in
		1966	F</tmp/debug.sock>, you could use this:
		1967
		1968	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug.sock perlprog
		1969
		1970	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		1971
		1972	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		1973	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
1394		1974
1395	=item C<PERL_ANYEVENT_MODEL>	1975	=item C<PERL_ANYEVENT_MODEL>
1396		1976
1397	This can be used to specify the event model to be used by AnyEvent, before	1977	This can be used to specify the event model to be used by AnyEvent, before
1398	auto detection and -probing kicks in. It must be a string consisting	1978	auto detection and -probing kicks in.
1399	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1979
		1980	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		1981	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1400	and the resulting module name is loaded and if the load was successful,	1982	resulting module name is loaded and - if the load was successful - used as
1401	used as event model. If it fails to load AnyEvent will proceed with	1983	event model backend. If it fails to load then AnyEvent will proceed with
1402	auto detection and -probing.	1984	auto detection and -probing.
1403		1985
1404	This functionality might change in future versions.	1986	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		1987	nothing gets prepended and the module name is used as-is (hint: C<::> at
		1988	the end of a string designates a module name and quotes it appropriately).
1405		1989
1406	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1990	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1407	could start your program like this:	1991	could start your program like this:
1408		1992
1409	PERL_ANYEVENT_MODEL=Perl perl ...	1993	PERL_ANYEVENT_MODEL=Perl perl ...
1410		1994
1411	=item C<PERL_ANYEVENT_PROTOCOLS>	1995	=item C<PERL_ANYEVENT_PROTOCOLS>
…		…
1441		2025
1442	=item C<PERL_ANYEVENT_MAX_FORKS>	2026	=item C<PERL_ANYEVENT_MAX_FORKS>
1443		2027
1444	The maximum number of child processes that C<AnyEvent::Util::fork_call>	2028	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1445	will create in parallel.	2029	will create in parallel.
		2030
		2031	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2032
		2033	The default value for the C<max_outstanding> parameter for the default DNS
		2034	resolver - this is the maximum number of parallel DNS requests that are
		2035	sent to the DNS server.
		2036
		2037	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2038
		2039	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2040	configuration) in the default resolver. When set to the empty string, no
		2041	default config will be used.
		2042
		2043	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2044
		2045	When neither C<ca_file> nor C<ca_path> was specified during
		2046	L<AnyEvent::TLS> context creation, and either of these environment
		2047	variables exist, they will be used to specify CA certificate locations
		2048	instead of a system-dependent default.
		2049
		2050	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2051
		2052	When these are set to C<1>, then the respective modules are not
		2053	loaded. Mostly good for testing AnyEvent itself.
1446		2054
1447	=back	2055	=back
1448		2056
1449	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2057	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1450		2058
…		…
1508	warn "read: $input\n"; # output what has been read	2116	warn "read: $input\n"; # output what has been read
1509	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2117	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1510	},	2118	},
1511	);	2119	);
1512		2120
1513	my $time_watcher; # can only be used once
1514
1515	sub new_timer {
1516	$timer = AnyEvent->timer (after => 1, cb => sub {	2121	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1517	warn "timeout\n"; # print 'timeout' about every second	2122	warn "timeout\n"; # print 'timeout' at most every second
1518	&new_timer; # and restart the time
1519	});	2123	});
1520	}
1521
1522	new_timer; # create first timer
1523		2124
1524	$cv->recv; # wait until user enters /^q/i	2125	$cv->recv; # wait until user enters /^q/i
1525		2126
1526	=head1 REAL-WORLD EXAMPLE	2127	=head1 REAL-WORLD EXAMPLE
1527		2128
…		…
1600		2201
1601	The actual code goes further and collects all errors (C<die>s, exceptions)	2202	The actual code goes further and collects all errors (C<die>s, exceptions)
1602	that occurred during request processing. The C<result> method detects	2203	that occurred during request processing. The C<result> method detects
1603	whether an exception as thrown (it is stored inside the $txn object)	2204	whether an exception as thrown (it is stored inside the $txn object)
1604	and just throws the exception, which means connection errors and other	2205	and just throws the exception, which means connection errors and other
1605	problems get reported tot he code that tries to use the result, not in a	2206	problems get reported to the code that tries to use the result, not in a
1606	random callback.	2207	random callback.
1607		2208
1608	All of this enables the following usage styles:	2209	All of this enables the following usage styles:
1609		2210
1610	1. Blocking:	2211	1. Blocking:
…		…
1658	through AnyEvent. The benchmark creates a lot of timers (with a zero	2259	through AnyEvent. The benchmark creates a lot of timers (with a zero
1659	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2260	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1660	which it is), lets them fire exactly once and destroys them again.	2261	which it is), lets them fire exactly once and destroys them again.
1661		2262
1662	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2263	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1663	distribution.	2264	distribution. It uses the L<AE> interface, which makes a real difference
		2265	for the EV and Perl backends only.
1664		2266
1665	=head3 Explanation of the columns	2267	=head3 Explanation of the columns
1666		2268
1667	I<watcher> is the number of event watchers created/destroyed. Since	2269	I<watcher> is the number of event watchers created/destroyed. Since
1668	different event models feature vastly different performances, each event	2270	different event models feature vastly different performances, each event
…		…
1689	watcher.	2291	watcher.
1690		2292
1691	=head3 Results	2293	=head3 Results
1692		2294
1693	name watchers bytes create invoke destroy comment	2295	name watchers bytes create invoke destroy comment
1694	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2296	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1695	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2297	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1696	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2298	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1697	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2299	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1698	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2300	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1699	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2301	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2302	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2303	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1700	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2304	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1701	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2305	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1702	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2306	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1703	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2307	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1704		2308
1705	=head3 Discussion	2309	=head3 Discussion
1706		2310
1707	The benchmark does I<not> measure scalability of the event loop very	2311	The benchmark does I<not> measure scalability of the event loop very
1708	well. For example, a select-based event loop (such as the pure perl one)	2312	well. For example, a select-based event loop (such as the pure perl one)
…		…
1720	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2324	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1721	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2325	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1722	cycles with POE.	2326	cycles with POE.
1723		2327
1724	C<EV> is the sole leader regarding speed and memory use, which are both	2328	C<EV> is the sole leader regarding speed and memory use, which are both
1725	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2329	maximal/minimal, respectively. When using the L<AE> API there is zero
		2330	overhead (when going through the AnyEvent API create is about 5-6 times
		2331	slower, with other times being equal, so still uses far less memory than
1726	far less memory than any other event loop and is still faster than Event	2332	any other event loop and is still faster than Event natively).
1727	natively.
1728		2333
1729	The pure perl implementation is hit in a few sweet spots (both the	2334	The pure perl implementation is hit in a few sweet spots (both the
1730	constant timeout and the use of a single fd hit optimisations in the perl	2335	constant timeout and the use of a single fd hit optimisations in the perl
1731	interpreter and the backend itself). Nevertheless this shows that it	2336	interpreter and the backend itself). Nevertheless this shows that it
1732	adds very little overhead in itself. Like any select-based backend its	2337	adds very little overhead in itself. Like any select-based backend its
1733	performance becomes really bad with lots of file descriptors (and few of	2338	performance becomes really bad with lots of file descriptors (and few of
1734	them active), of course, but this was not subject of this benchmark.	2339	them active), of course, but this was not subject of this benchmark.
1735		2340
1736	The C<Event> module has a relatively high setup and callback invocation	2341	The C<Event> module has a relatively high setup and callback invocation
1737	cost, but overall scores in on the third place.	2342	cost, but overall scores in on the third place.
		2343
		2344	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2345	when using its pure perl backend.
1738		2346
1739	C<Glib>'s memory usage is quite a bit higher, but it features a	2347	C<Glib>'s memory usage is quite a bit higher, but it features a
1740	faster callback invocation and overall ends up in the same class as	2348	faster callback invocation and overall ends up in the same class as
1741	C<Event>. However, Glib scales extremely badly, doubling the number of	2349	C<Event>. However, Glib scales extremely badly, doubling the number of
1742	watchers increases the processing time by more than a factor of four,	2350	watchers increases the processing time by more than a factor of four,
…		…
1803	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2411	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1804	(1%) are active. This mirrors the activity of large servers with many	2412	(1%) are active. This mirrors the activity of large servers with many
1805	connections, most of which are idle at any one point in time.	2413	connections, most of which are idle at any one point in time.
1806		2414
1807	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2415	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1808	distribution.	2416	distribution. It uses the L<AE> interface, which makes a real difference
		2417	for the EV and Perl backends only.
1809		2418
1810	=head3 Explanation of the columns	2419	=head3 Explanation of the columns
1811		2420
1812	I<sockets> is the number of sockets, and twice the number of "servers" (as	2421	I<sockets> is the number of sockets, and twice the number of "servers" (as
1813	each server has a read and write socket end).	2422	each server has a read and write socket end).
…		…
1820	it to another server. This includes deleting the old timeout and creating	2429	it to another server. This includes deleting the old timeout and creating
1821	a new one that moves the timeout into the future.	2430	a new one that moves the timeout into the future.
1822		2431
1823	=head3 Results	2432	=head3 Results
1824		2433
1825	name sockets create request	2434	name sockets create request
1826	EV 20000 69.01 11.16	2435	EV 20000 62.66 7.99
1827	Perl 20000 73.32 35.87	2436	Perl 20000 68.32 32.64
1828	Event 20000 212.62 257.32	2437	IOAsync 20000 174.06 101.15 epoll
1829	Glib 20000 651.16 1896.30	2438	IOAsync 20000 174.67 610.84 poll
		2439	Event 20000 202.69 242.91
		2440	Glib 20000 557.01 1689.52
1830	POE 20000 349.67 12317.24 uses POE::Loop::Event	2441	POE 20000 341.54 12086.32 uses POE::Loop::Event
1831		2442
1832	=head3 Discussion	2443	=head3 Discussion
1833		2444
1834	This benchmark I<does> measure scalability and overall performance of the	2445	This benchmark I<does> measure scalability and overall performance of the
1835	particular event loop.	2446	particular event loop.
…		…
1837	EV is again fastest. Since it is using epoll on my system, the setup time	2448	EV is again fastest. Since it is using epoll on my system, the setup time
1838	is relatively high, though.	2449	is relatively high, though.
1839		2450
1840	Perl surprisingly comes second. It is much faster than the C-based event	2451	Perl surprisingly comes second. It is much faster than the C-based event
1841	loops Event and Glib.	2452	loops Event and Glib.
		2453
		2454	IO::Async performs very well when using its epoll backend, and still quite
		2455	good compared to Glib when using its pure perl backend.
1842		2456
1843	Event suffers from high setup time as well (look at its code and you will	2457	Event suffers from high setup time as well (look at its code and you will
1844	understand why). Callback invocation also has a high overhead compared to	2458	understand why). Callback invocation also has a high overhead compared to
1845	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2459	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1846	uses select or poll in basically all documented configurations.	2460	uses select or poll in basically all documented configurations.
…		…
1958	As you can see, the AnyEvent + EV combination even beats the	2572	As you can see, the AnyEvent + EV combination even beats the
1959	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2573	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1960	backend easily beats IO::Lambda and POE.	2574	backend easily beats IO::Lambda and POE.
1961		2575
1962	And even the 100% non-blocking version written using the high-level (and	2576	And even the 100% non-blocking version written using the high-level (and
1963	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a	2577	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
1964	large margin, even though it does all of DNS, tcp-connect and socket I/O	2578	higher level ("unoptimised") abstractions by a large margin, even though
1965	in a non-blocking way.	2579	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1966		2580
1967	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2581	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
1968	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are	2582	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
1969	part of the IO::lambda distribution and were used without any changes.	2583	part of the IO::Lambda distribution and were used without any changes.
1970		2584
1971		2585
1972	=head1 SIGNALS	2586	=head1 SIGNALS
1973		2587
1974	AnyEvent currently installs handlers for these signals:	2588	AnyEvent currently installs handlers for these signals:
…		…
1979		2593
1980	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2594	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1981	emulation for event loops that do not support them natively. Also, some	2595	emulation for event loops that do not support them natively. Also, some
1982	event loops install a similar handler.	2596	event loops install a similar handler.
1983		2597
1984	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will	2598	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
1985	reset it to default, to avoid losing child exit statuses.	2599	AnyEvent will reset it to default, to avoid losing child exit statuses.
1986		2600
1987	=item SIGPIPE	2601	=item SIGPIPE
1988		2602
1989	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2603	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1990	when AnyEvent gets loaded.	2604	when AnyEvent gets loaded.
…		…
2008	if $SIG{CHLD} eq 'IGNORE';	2622	if $SIG{CHLD} eq 'IGNORE';
2009		2623
2010	$SIG{PIPE} = sub { }	2624	$SIG{PIPE} = sub { }
2011	unless defined $SIG{PIPE};	2625	unless defined $SIG{PIPE};
2012		2626
		2627	=head1 RECOMMENDED/OPTIONAL MODULES
		2628
		2629	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2630	its built-in modules) are required to use it.
		2631
		2632	That does not mean that AnyEvent won't take advantage of some additional
		2633	modules if they are installed.
		2634
		2635	This section explains which additional modules will be used, and how they
		2636	affect AnyEvent's operation.
		2637
		2638	=over 4
		2639
		2640	=item L<Async::Interrupt>
		2641
		2642	This slightly arcane module is used to implement fast signal handling: To
		2643	my knowledge, there is no way to do completely race-free and quick
		2644	signal handling in pure perl. To ensure that signals still get
		2645	delivered, AnyEvent will start an interval timer to wake up perl (and
		2646	catch the signals) with some delay (default is 10 seconds, look for
		2647	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2648
		2649	If this module is available, then it will be used to implement signal
		2650	catching, which means that signals will not be delayed, and the event loop
		2651	will not be interrupted regularly, which is more efficient (and good for
		2652	battery life on laptops).
		2653
		2654	This affects not just the pure-perl event loop, but also other event loops
		2655	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2656
		2657	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2658	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2659	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2660	does nothing for those backends.
		2661
		2662	=item L<EV>
		2663
		2664	This module isn't really "optional", as it is simply one of the backend
		2665	event loops that AnyEvent can use. However, it is simply the best event
		2666	loop available in terms of features, speed and stability: It supports
		2667	the AnyEvent API optimally, implements all the watcher types in XS, does
		2668	automatic timer adjustments even when no monotonic clock is available,
		2669	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2670	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2671	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2672
		2673	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2674	then this module will do nothing for you.
		2675
		2676	=item L<Guard>
		2677
		2678	The guard module, when used, will be used to implement
		2679	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2680	lot less memory), but otherwise doesn't affect guard operation much. It is
		2681	purely used for performance.
		2682
		2683	=item L<JSON> and L<JSON::XS>
		2684
		2685	One of these modules is required when you want to read or write JSON data
		2686	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2687	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2688
		2689	=item L<Net::SSLeay>
		2690
		2691	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2692	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2693	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2694
		2695	=item L<Time::HiRes>
		2696
		2697	This module is part of perl since release 5.008. It will be used when the
		2698	chosen event library does not come with a timing source of its own. The
		2699	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2700	try to use a monotonic clock for timing stability.
		2701
		2702	=back
		2703
		2704
2013	=head1 FORK	2705	=head1 FORK
2014		2706
2015	Most event libraries are not fork-safe. The ones who are usually are	2707	Most event libraries are not fork-safe. The ones who are usually are
2016	because they rely on inefficient but fork-safe C<select> or C<poll>	2708	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2017	calls. Only L<EV> is fully fork-aware.	2709	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2710	are usually badly thought-out hacks that are incompatible with fork in
		2711	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2712	continue event-processing in both parent and child (or both, if you know
		2713	what you are doing).
		2714
		2715	This means that, in general, you cannot fork and do event processing in
		2716	the child if the event library was initialised before the fork (which
		2717	usually happens when the first AnyEvent watcher is created, or the library
		2718	is loaded).
2018		2719
2019	If you have to fork, you must either do so I<before> creating your first	2720	If you have to fork, you must either do so I<before> creating your first
2020	watcher OR you must not use AnyEvent at all in the child.	2721	watcher OR you must not use AnyEvent at all in the child OR you must do
		2722	something completely out of the scope of AnyEvent.
		2723
		2724	The problem of doing event processing in the parent I<and> the child
		2725	is much more complicated: even for backends that I<are> fork-aware or
		2726	fork-safe, their behaviour is not usually what you want: fork clones all
		2727	watchers, that means all timers, I/O watchers etc. are active in both
		2728	parent and child, which is almost never what you want. USing C<exec>
		2729	to start worker children from some kind of manage rprocess is usually
		2730	preferred, because it is much easier and cleaner, at the expense of having
		2731	to have another binary.
2021		2732
2022		2733
2023	=head1 SECURITY CONSIDERATIONS	2734	=head1 SECURITY CONSIDERATIONS
2024		2735
2025	AnyEvent can be forced to load any event model via	2736	AnyEvent can be forced to load any event model via
…		…
2055	pronounced).	2766	pronounced).
2056		2767
2057		2768
2058	=head1 SEE ALSO	2769	=head1 SEE ALSO
2059		2770
		2771	Tutorial/Introduction: L<AnyEvent::Intro>.
		2772
		2773	FAQ: L<AnyEvent::FAQ>.
		2774
2060	Utility functions: L<AnyEvent::Util>.	2775	Utility functions: L<AnyEvent::Util>.
2061		2776
2062	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2777	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
2063	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2778	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2064		2779
2065	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2780	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2066	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2781	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2067	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2782	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2068	L<AnyEvent::Impl::POE>.	2783	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2069		2784
2070	Non-blocking file handles, sockets, TCP clients and	2785	Non-blocking file handles, sockets, TCP clients and
2071	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2786	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2072		2787
2073	Asynchronous DNS: L<AnyEvent::DNS>.	2788	Asynchronous DNS: L<AnyEvent::DNS>.
2074		2789
2075	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2790	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2076		2791
2077	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2792	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2793	L<AnyEvent::HTTP>.
2078		2794
2079		2795
2080	=head1 AUTHOR	2796	=head1 AUTHOR
2081		2797
2082	Marc Lehmann <schmorp@schmorp.de>	2798	Marc Lehmann <schmorp@schmorp.de>

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