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Revision 1.350 by root, Tue Aug 2 20:02:44 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::Impl::Perl>,
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::Impl::Perl> 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
136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
137	explicitly and enjoy the high availability of that event loop :)	149	explicitly and enjoy the high availability of that event loop :)
138		150
…		…
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
…		…
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
…		…
392		469
393	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
394	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
395	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
396		473
397	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
398	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
399	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
400		480
401	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
402	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which the latency and race problems
		488	mentioned in the description of signal watchers apply.
404		489
405	Example: fork a process and wait for it	490	Example: fork a process and wait for it
406		491
407	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
408		493
…		…
420	# do something else, then wait for process exit	505	# do something else, then wait for process exit
421	$done->recv;	506	$done->recv;
422		507
423	=head2 IDLE WATCHERS	508	=head2 IDLE WATCHERS
424		509
425	Sometimes there is a need to do something, but it is not so important	510	$w = AnyEvent->idle (cb => <callback>);
426	to do it instantly, but only when there is nothing better to do. This
427	"nothing better to do" is usually defined to be "no other events need
428	attention by the event loop".
429		511
430	Idle watchers ideally get invoked when the event loop has nothing	512	This will repeatedly invoke the callback after the process becomes idle,
431	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.
432	events. Instead of blocking, the idle watcher is invoked.
433		514
434	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
435	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
436	will simply call the callback "from time to time".	526	will simply call the callback "from time to time".
437		527
438	Example: read lines from STDIN, but only process them when the	528	Example: read lines from STDIN, but only process them when the
439	program is otherwise idle:	529	program is otherwise idle:
…		…
455	});	545	});
456	});	546	});
457		547
458	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
459		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
		554
460	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
461	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
462	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
463		558
464	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
465	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).
466		561
467	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
468	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.
469		566
470	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
471	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
472
473	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
474	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
475	the results).	571	the results).
476		572
477	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
478	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
479	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<<
480	->send >> method).	576	->send >> method).
481		577
482	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
483	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:
484	in time where multiple outstanding events have been processed. And yet	580
485	another way to call them is transactions - each condition variable can be	581	=over 4
486	used to represent a transaction, which finishes at some point and delivers	582
487	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
488		601
489	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
490	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,
491	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
492	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
…		…
505		618
506	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
507	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
508	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
509	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
510	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
511		624
512	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
513	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
514	for the send to occur.	627	for the send to occur.
515		628
516	Example: wait for a timer.	629	Example: wait for a timer.
517		630
518	# wait till the result is ready	631	# condition: "wait till the timer is fired"
519	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
520		633
521	# do something such as adding a timer	634	# create the timer - we could wait for, say
522	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
523	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
524	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
525	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
526	after => 1,	639	after => 1,
527	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
528	);	641	);
529		642
530	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
531	# calls send	644	# calls ->send
532	$result_ready->recv;	645	$timer_fired->recv;
533		646
534	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
535	condition variables are also code references.	648	variables are also callable directly.
536		649
537	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
538	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
539	$done->recv;	652	$done->recv;
540		653
…		…
546		659
547	...	660	...
548		661
549	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
550		663
551	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
552	results are available:	665	results are available:
553		666
554	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
555	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
556	});	669	});
…		…
574	immediately from within send.	687	immediately from within send.
575		688
576	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
577	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
578		691
579	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
580	(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
581	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
582	overloading, so as tempting as it may be, passing a condition variable
583	instead of a callback does not work. Both the pure perl and EV loops
584	support overloading, however, as well as all functions that use perl to
585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
586	example).
587		695
588	=item $cv->croak ($error)	696	=item $cv->croak ($error)
589		697
590	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
591	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
592		700
593	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
594	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.
595		707
596	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
597		709
598	=item $cv->end	710	=item $cv->end
599
600	These two methods are EXPERIMENTAL and MIGHT CHANGE.
601		711
602	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
603	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
604	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
605		715
606	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
607	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
608	>>, 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
609	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
610	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.
611		722
612	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:
613		730
614	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
615		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
616	my %result;	757	my %result;
617	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
618		759
619	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
620	$cv->begin;	761	$cv->begin;
621	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
622	$result{$host} = ...;	763	$result{$host} = ...;
…		…
637	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
638	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
639	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
640	doesn't execute once).	781	doesn't execute once).
641		782
642	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
643	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
644	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
645	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>.
646		788
647	=back	789	=back
648		790
649	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
650		792
…		…
654	=over 4	796	=over 4
655		797
656	=item $cv->recv	798	=item $cv->recv
657		799
658	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
659	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
660	normally.	802	normally.
661		803
662	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
663	will return immediately.	805	will return immediately.
664		806
…		…
666	function will call C<croak>.	808	function will call C<croak>.
667		809
668	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,
669	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
670		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
671	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
672	(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
673	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
674	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
675	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
676	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,
677	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
678		827
679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
680	sensibly have two C<< ->recv >>'s in parallel, as that would require
681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
682	can supply.
683
684	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
685	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
686	versions and also integrates coroutines into AnyEvent, making blocking
687	C<< ->recv >> calls perfectly safe as long as they are done from another
688	coroutine (one that doesn't run the event loop).
689
690	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
691	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
692	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
693	waits otherwise.	831	waits otherwise.
694		832
695	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
701		839
702	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
703	replaces it before doing so.	841	replaces it before doing so.
704		842
705	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
706	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
707	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
708	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.
709		848
710	=back	849	=back
711		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 implementation, 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::FLTK based on FLTK.
		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
712	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
713		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
714	=over 4	919	=over 4
715		920
716	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
717		922
718	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
719	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
720	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
721	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
722	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
723		930	will be C<urxvt::anyevent>).
724	The known classes so far are:
725
726	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
727	AnyEvent::Impl::Event based on Event, second best choice.
728	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
729	AnyEvent::Impl::Glib based on Glib, third-best choice.
730	AnyEvent::Impl::Tk based on Tk, very bad choice.
731	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
732	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
733	AnyEvent::Impl::POE based on POE, not generic enough for full support.
734
735	There is no support for WxWidgets, as WxWidgets has no support for
736	watching file handles. However, you can use WxWidgets through the
737	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
738	second, which was considered to be too horrible to even consider for
739	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
740	it's adaptor.
741
742	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
743	autodetecting them.
744		931
745	=item AnyEvent::detect	932	=item AnyEvent::detect
746		933
747	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
748	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
749	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
750	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>.
751		941
752	=item $guard = AnyEvent::post_detect { BLOCK }	942	=item $guard = AnyEvent::post_detect { BLOCK }
753		943
754	Arranges for the code block to be executed as soon as the event model is	944	Arranges for the code block to be executed as soon as the event model is
755	autodetected (or immediately if this has already happened).	945	autodetected (or immediately if that has already happened).
		946
		947	The block will be executed I<after> the actual backend has been detected
		948	(C<$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.
756		957
757	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
758	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
759	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 ||= $guard;
760		978
761	=item @AnyEvent::post_detect	979	=item @AnyEvent::post_detect
762		980
763	If there are any code references in this array (you can C<push> to it	981	If there are any code references in this array (you can C<push> to it
764	before or after loading AnyEvent), then they will called directly after	982	before or after loading AnyEvent), then they will be called directly
765	the event loop has been chosen.	983	after the event loop has been chosen.
766		984
767	You should check C<$AnyEvent::MODEL> before adding to this array, though:	985	You should check C<$AnyEvent::MODEL> before adding to this array, though:
768	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
769	and the array will be ignored.	987	array will be ignored.
770		988
771	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	}
772		1009
773	=back	1010	=back
774		1011
775	=head1 WHAT TO DO IN A MODULE	1012	=head1 WHAT TO DO IN A MODULE
776		1013
…		…
787	because it will stall the whole program, and the whole point of using	1024	because it will stall the whole program, and the whole point of using
788	events is to stay interactive.	1025	events is to stay interactive.
789		1026
790	It is fine, however, to call C<< ->recv >> when the user of your module	1027	It is fine, however, to call C<< ->recv >> when the user of your module
791	requests it (i.e. if you create a http request object ad have a method	1028	requests it (i.e. if you create a http request object ad have a method
792	called C<results> that returns the results, it should call C<< ->recv >>	1029	called C<results> that returns the results, it may call C<< ->recv >>
793	freely, as the user of your module knows what she is doing. always).	1030	freely, as the user of your module knows what she is doing. Always).
794		1031
795	=head1 WHAT TO DO IN THE MAIN PROGRAM	1032	=head1 WHAT TO DO IN THE MAIN PROGRAM
796		1033
797	There will always be a single main program - the only place that should	1034	There will always be a single main program - the only place that should
798	dictate which event model to use.	1035	dictate which event model to use.
799		1036
800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1037	If the program is not event-based, it need not do anything special, even
801	do anything special (it does not need to be event-based) and let AnyEvent	1038	when it depends on a module that uses an AnyEvent. If the program itself
802	decide which implementation to chose if some module relies on it.	1039	uses AnyEvent, but does not care which event loop is used, all it needs
		1040	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1041	available loop implementation.
803		1042
804	If the main program relies on a specific event model - for example, in	1043	If the main program relies on a specific event model - for example, in
805	Gtk2 programs you have to rely on the Glib module - you should load the	1044	Gtk2 programs you have to rely on the Glib module - you should load the
806	event module before loading AnyEvent or any module that uses it: generally	1045	event module before loading AnyEvent or any module that uses it: generally
807	speaking, you should load it as early as possible. The reason is that	1046	speaking, you should load it as early as possible. The reason is that
808	modules might create watchers when they are loaded, and AnyEvent will	1047	modules might create watchers when they are loaded, and AnyEvent will
809	decide on the event model to use as soon as it creates watchers, and it	1048	decide on the event model to use as soon as it creates watchers, and it
810	might chose the wrong one unless you load the correct one yourself.	1049	might choose the wrong one unless you load the correct one yourself.
811		1050
812	You can chose to use a pure-perl implementation by loading the	1051	You can chose to use a pure-perl implementation by loading the
813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1052	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
814	everywhere, but letting AnyEvent chose the model is generally better.	1053	everywhere, but letting AnyEvent chose the model is generally better.
815		1054
…		…
831		1070
832		1071
833	=head1 OTHER MODULES	1072	=head1 OTHER MODULES
834		1073
835	The following is a non-exhaustive list of additional modules that use	1074	The following is a non-exhaustive list of additional modules that use
836	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1075	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
837	in the same program. Some of the modules come with AnyEvent, some are	1076	modules and other event loops in the same program. Some of the modules
838	available via CPAN.	1077	come as part of AnyEvent, the others are available via CPAN.
839		1078
840	=over 4	1079	=over 4
841		1080
842	=item L<AnyEvent::Util>	1081	=item L<AnyEvent::Util>
843		1082
844	Contains various utility functions that replace often-used but blocking	1083	Contains various utility functions that replace often-used blocking
845	functions such as C<inet_aton> by event-/callback-based versions.	1084	functions such as C<inet_aton> with event/callback-based versions.
846		1085
847	=item L<AnyEvent::Socket>	1086	=item L<AnyEvent::Socket>
848		1087
849	Provides various utility functions for (internet protocol) sockets,	1088	Provides various utility functions for (internet protocol) sockets,
850	addresses and name resolution. Also functions to create non-blocking tcp	1089	addresses and name resolution. Also functions to create non-blocking tcp
…		…
852		1091
853	=item L<AnyEvent::Handle>	1092	=item L<AnyEvent::Handle>
854		1093
855	Provide read and write buffers, manages watchers for reads and writes,	1094	Provide read and write buffers, manages watchers for reads and writes,
856	supports raw and formatted I/O, I/O queued and fully transparent and	1095	supports raw and formatted I/O, I/O queued and fully transparent and
857	non-blocking SSL/TLS.	1096	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
858		1097
859	=item L<AnyEvent::DNS>	1098	=item L<AnyEvent::DNS>
860		1099
861	Provides rich asynchronous DNS resolver capabilities.	1100	Provides rich asynchronous DNS resolver capabilities.
862		1101
		1102	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1103
		1104	Implement event-based interfaces to the protocols of the same name (for
		1105	the curious, IGS is the International Go Server and FCP is the Freenet
		1106	Client Protocol).
		1107
		1108	=item L<AnyEvent::Handle::UDP>
		1109
		1110	Here be danger!
		1111
		1112	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1113	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1114	its use of a stream-based API with a protocol that isn't streamable, that
		1115	the only way to improve it is to delete it.
		1116
		1117	It features data corruption (but typically only under load) and general
		1118	confusion. On top, the author is not only clueless about UDP but also
		1119	fact-resistant - some gems of his understanding: "connect doesn't work
		1120	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1121	packets", "I don't need to implement proper error checking as UDP doesn't
		1122	support error checking" and so on - he doesn't even understand what's
		1123	wrong with his module when it is explained to him.
		1124
863	=item L<AnyEvent::HTTP>	1125	=item L<AnyEvent::DBI>
864		1126
865	A simple-to-use HTTP library that is capable of making a lot of concurrent	1127	Executes L<DBI> requests asynchronously in a proxy process for you,
866	HTTP requests.	1128	notifying you in an event-based way when the operation is finished.
		1129
		1130	=item L<AnyEvent::AIO>
		1131
		1132	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1133	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1134	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1135	file I/O, and much more.
867		1136
868	=item L<AnyEvent::HTTPD>	1137	=item L<AnyEvent::HTTPD>
869		1138
870	Provides a simple web application server framework.	1139	A simple embedded webserver.
871		1140
872	=item L<AnyEvent::FastPing>	1141	=item L<AnyEvent::FastPing>
873		1142
874	The fastest ping in the west.	1143	The fastest ping in the west.
875		1144
876	=item L<AnyEvent::DBI>
877
878	Executes L<DBI> requests asynchronously in a proxy process.
879
880	=item L<AnyEvent::AIO>
881
882	Truly asynchronous I/O, should be in the toolbox of every event
883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
884	together.
885
886	=item L<AnyEvent::BDB>
887
888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
889	L<BDB> and AnyEvent together.
890
891	=item L<AnyEvent::GPSD>
892
893	A non-blocking interface to gpsd, a daemon delivering GPS information.
894
895	=item L<AnyEvent::IGS>
896
897	A non-blocking interface to the Internet Go Server protocol (used by
898	L<App::IGS>).
899
900	=item L<AnyEvent::IRC>
901
902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
903
904	=item L<Net::XMPP2>
905
906	AnyEvent based XMPP (Jabber protocol) module family.
907
908	=item L<Net::FCP>
909
910	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
911	of AnyEvent.
912
913	=item L<Event::ExecFlow>
914
915	High level API for event-based execution flow control.
916
917	=item L<Coro>	1145	=item L<Coro>
918		1146
919	Has special support for AnyEvent via L<Coro::AnyEvent>.	1147	Has special support for AnyEvent via L<Coro::AnyEvent>.
920		1148
921	=item L<IO::Lambda>
922
923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
924
925	=back	1149	=back
926		1150
927	=cut	1151	=cut
928		1152
929	package AnyEvent;	1153	package AnyEvent;
930		1154
931	no warnings;	1155	# basically a tuned-down version of common::sense
932	use strict qw(vars subs);	1156	sub common_sense {
		1157	# from common:.sense 3.4
		1158	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1159	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1160	$^H |= 0x00000600;
		1161	}
933		1162
		1163	BEGIN { AnyEvent::common_sense }
		1164
934	use Carp;	1165	use Carp ();
935		1166
936	our $VERSION = 4.411;	1167	our $VERSION = '5.34';
937	our $MODEL;	1168	our $MODEL;
938		1169
939	our $AUTOLOAD;	1170	our $AUTOLOAD;
940	our @ISA;	1171	our @ISA;
941		1172
942	our @REGISTRY;	1173	our @REGISTRY;
943		1174
944	our $WIN32;	1175	our $VERBOSE;
945		1176
946	BEGIN {	1177	BEGIN {
947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1178	require "AnyEvent/constants.pl";
		1179
948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1180	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
949		1181
950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1182	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
951	if ${^TAINT};	1183	if ${^TAINT};
952	}
953		1184
954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1185	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1186
		1187	}
		1188
		1189	our $MAX_SIGNAL_LATENCY = 10;
955		1190
956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1191	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
957		1192
958	{	1193	{
959	my $idx;	1194	my $idx;
…		…
961	for reverse split /\s*,\s*/,	1196	for reverse split /\s*,\s*/,
962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1197	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
963	}	1198	}
964		1199
965	my @models = (	1200	my @models = (
966	[EV:: => AnyEvent::Impl::EV::],	1201	[EV:: => AnyEvent::Impl::EV:: , 1],
967	[Event:: => AnyEvent::Impl::Event::],
968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1202	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
969	# everything below here will not be autoprobed	1203	# everything below here will not (normally) be autoprobed
970	# as the pureperl backend should work everywhere	1204	# as the pureperl backend should work everywhere
971	# and is usually faster	1205	# and is usually faster
		1206	[Event:: => AnyEvent::Impl::Event::, 1],
		1207	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1208	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1209	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1210	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1211	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1212	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
977	[Wx:: => AnyEvent::Impl::POE::],	1213	[Wx:: => AnyEvent::Impl::POE::],
978	[Prima:: => AnyEvent::Impl::POE::],	1214	[Prima:: => AnyEvent::Impl::POE::],
		1215	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::],
		1216	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1217	[FLTK:: => AnyEvent::Impl::FLTK::],
979	);	1218	);
980		1219
981	our %method = map +($_ => 1),	1220	our %method = map +($_ => 1),
982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1221	qw(io timer time now now_update signal child idle condvar DESTROY);
983		1222
984	our @post_detect;	1223	our @post_detect;
985		1224
986	sub post_detect(&) {	1225	sub post_detect(&) {
987	my ($cb) = @_;	1226	my ($cb) = @_;
988		1227
989	if ($MODEL) {
990	$cb->();
991
992	1
993	} else {
994	push @post_detect, $cb;	1228	push @post_detect, $cb;
995		1229
996	defined wantarray	1230	defined wantarray
997	? bless \$cb, "AnyEvent::Util::postdetect"	1231	? bless \$cb, "AnyEvent::Util::postdetect"
998	: ()	1232	: ()
999	}
1000	}	1233	}
1001		1234
1002	sub AnyEvent::Util::postdetect::DESTROY {	1235	sub AnyEvent::Util::postdetect::DESTROY {
1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1236	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1004	}	1237	}
1005		1238
1006	sub detect() {	1239	sub detect() {
		1240	# free some memory
		1241	*detect = sub () { $MODEL };
		1242
		1243	local $!; # for good measure
		1244	local $SIG{__DIE__};
		1245
		1246	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1247	my $model = "AnyEvent::Impl::$1";
		1248	if (eval "require $model") {
		1249	$MODEL = $model;
		1250	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1251	} else {
		1252	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1253	}
		1254	}
		1255
		1256	# check for already loaded models
1007	unless ($MODEL) {	1257	unless ($MODEL) {
1008	no strict 'refs';	1258	for (@REGISTRY, @models) {
1009	local $SIG{__DIE__};	1259	my ($package, $model) = @$_;
1010		1260	if (${"$package\::VERSION"} > 0) {
1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1012	my $model = "AnyEvent::Impl::$1";
1013	if (eval "require $model") {	1261	if (eval "require $model") {
1014	$MODEL = $model;	1262	$MODEL = $model;
1015	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1263	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1016	} else {	1264	last;
1017	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1265	}
1018	}	1266	}
1019	}	1267	}
1020		1268
1021	# check for already loaded models
1022	unless ($MODEL) {	1269	unless ($MODEL) {
		1270	# try to autoload a model
1023	for (@REGISTRY, @models) {	1271	for (@REGISTRY, @models) {
1024	my ($package, $model) = @$_;	1272	my ($package, $model, $autoload) = @$_;
		1273	if (
		1274	$autoload
		1275	and eval "require $package"
1025	if (${"$package\::VERSION"} > 0) {	1276	and ${"$package\::VERSION"} > 0
1026	if (eval "require $model") {	1277	and eval "require $model"
		1278	) {
1027	$MODEL = $model;	1279	$MODEL = $model;
1028	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1280	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1029	last;	1281	last;
1030	}
1031	}	1282	}
1032	}	1283	}
1033		1284
1034	unless ($MODEL) {
1035	# try to load a model
1036
1037	for (@REGISTRY, @models) {
1038	my ($package, $model) = @$_;
1039	if (eval "require $package"
1040	and ${"$package\::VERSION"} > 0
1041	and eval "require $model") {
1042	$MODEL = $model;
1043	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1044	last;
1045	}
1046	}
1047
1048	$MODEL	1285	$MODEL
1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1286	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
1050	}
1051	}	1287	}
1052
1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1054
1055	unshift @ISA, $MODEL;
1056
1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1058
1059	(shift @post_detect)->() while @post_detect;
1060	}	1288	}
		1289
		1290	@models = (); # free probe data
		1291
		1292	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1293	unshift @ISA, $MODEL;
		1294
		1295	# now nuke some methods that are overridden by the backend.
		1296	# SUPER is not allowed.
		1297	for (qw(time signal child idle)) {
		1298	undef &{"AnyEvent::Base::$_"}
		1299	if defined &{"$MODEL\::$_"};
		1300	}
		1301
		1302	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1303	eval { require AnyEvent::Strict };
		1304	warn "AnyEvent: cannot load AnyEvent::Strict: $@"
		1305	if $@ && $VERBOSE;
		1306	}
		1307
		1308	(shift @post_detect)->() while @post_detect;
		1309
		1310	*post_detect = sub(&) {
		1311	shift->();
		1312
		1313	undef
		1314	};
1061		1315
1062	$MODEL	1316	$MODEL
1063	}	1317	}
1064		1318
1065	sub AUTOLOAD {	1319	sub AUTOLOAD {
1066	(my $func = $AUTOLOAD) =~ s/.*://;	1320	(my $func = $AUTOLOAD) =~ s/.*://;
1067		1321
1068	$method{$func}	1322	$method{$func}
1069	or croak "$func: not a valid method for AnyEvent objects";	1323	or Carp::croak "$func: not a valid AnyEvent class method";
1070		1324
1071	detect unless $MODEL;	1325	detect;
1072		1326
1073	my $class = shift;	1327	my $class = shift;
1074	$class->$func (@_);	1328	$class->$func (@_);
1075	}	1329	}
1076		1330
1077	# utility function to dup a filehandle. this is used by many backends	1331	# utility function to dup a filehandle. this is used by many backends
1078	# to support binding more than one watcher per filehandle (they usually	1332	# to support binding more than one watcher per filehandle (they usually
1079	# allow only one watcher per fd, so we dup it to get a different one).	1333	# allow only one watcher per fd, so we dup it to get a different one).
1080	sub _dupfh($$$$) {	1334	sub _dupfh($$;$$) {
1081	my ($poll, $fh, $r, $w) = @_;	1335	my ($poll, $fh, $r, $w) = @_;
1082		1336
1083	# cygwin requires the fh mode to be matching, unix doesn't	1337	# cygwin requires the fh mode to be matching, unix doesn't
1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1338	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1085	: $poll eq "w" ? ($w, ">")
1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1087		1339
1088	open my $fh2, "$mode&" . fileno $fh	1340	open my $fh2, $mode, $fh
1089	or die "cannot dup() filehandle: $!,";	1341	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1090		1342
1091	# we assume CLOEXEC is already set by perl in all important cases	1343	# we assume CLOEXEC is already set by perl in all important cases
1092		1344
1093	($fh2, $rw)	1345	($fh2, $rw)
1094	}	1346	}
1095		1347
		1348	=head1 SIMPLIFIED AE API
		1349
		1350	Starting with version 5.0, AnyEvent officially supports a second, much
		1351	simpler, API that is designed to reduce the calling, typing and memory
		1352	overhead by using function call syntax and a fixed number of parameters.
		1353
		1354	See the L<AE> manpage for details.
		1355
		1356	=cut
		1357
		1358	package AE;
		1359
		1360	our $VERSION = $AnyEvent::VERSION;
		1361
		1362	# fall back to the main API by default - backends and AnyEvent::Base
		1363	# implementations can overwrite these.
		1364
		1365	sub io($$$) {
		1366	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1367	}
		1368
		1369	sub timer($$$) {
		1370	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1371	}
		1372
		1373	sub signal($$) {
		1374	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1375	}
		1376
		1377	sub child($$) {
		1378	AnyEvent->child (pid => $_[0], cb => $_[1])
		1379	}
		1380
		1381	sub idle($) {
		1382	AnyEvent->idle (cb => $_[0])
		1383	}
		1384
		1385	sub cv(;&) {
		1386	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1387	}
		1388
		1389	sub now() {
		1390	AnyEvent->now
		1391	}
		1392
		1393	sub now_update() {
		1394	AnyEvent->now_update
		1395	}
		1396
		1397	sub time() {
		1398	AnyEvent->time
		1399	}
		1400
1096	package AnyEvent::Base;	1401	package AnyEvent::Base;
1097		1402
1098	# default implementations for many methods	1403	# default implementations for many methods
1099		1404
1100	BEGIN {	1405	sub time {
		1406	eval q{ # poor man's autoloading {}
		1407	# probe for availability of Time::HiRes
1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1408	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1409	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1102	*_time = \&Time::HiRes::time;	1410	*AE::time = \&Time::HiRes::time;
1103	# if (eval "use POSIX (); (POSIX::times())...	1411	# if (eval "use POSIX (); (POSIX::times())...
1104	} else {	1412	} else {
		1413	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1105	*_time = sub { time }; # epic fail	1414	*AE::time = sub (){ time }; # epic fail
		1415	}
		1416
		1417	*time = sub { AE::time }; # different prototypes
		1418	};
		1419	die if $@;
		1420
		1421	&time
		1422	}
		1423
		1424	*now = \&time;
		1425
		1426	sub now_update { }
		1427
		1428	# default implementation for ->condvar
		1429
		1430	sub condvar {
		1431	eval q{ # poor man's autoloading {}
		1432	*condvar = sub {
		1433	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1434	};
		1435
		1436	*AE::cv = sub (;&) {
		1437	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1438	};
		1439	};
		1440	die if $@;
		1441
		1442	&condvar
		1443	}
		1444
		1445	# default implementation for ->signal
		1446
		1447	our $HAVE_ASYNC_INTERRUPT;
		1448
		1449	sub _have_async_interrupt() {
		1450	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1451	&& eval "use Async::Interrupt 1.02 (); 1")
		1452	unless defined $HAVE_ASYNC_INTERRUPT;
		1453
		1454	$HAVE_ASYNC_INTERRUPT
		1455	}
		1456
		1457	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1458	our (%SIG_ASY, %SIG_ASY_W);
		1459	our ($SIG_COUNT, $SIG_TW);
		1460
		1461	# install a dummy wakeup watcher to reduce signal catching latency
		1462	# used by Impls
		1463	sub _sig_add() {
		1464	unless ($SIG_COUNT++) {
		1465	# try to align timer on a full-second boundary, if possible
		1466	my $NOW = AE::now;
		1467
		1468	$SIG_TW = AE::timer
		1469	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1470	$MAX_SIGNAL_LATENCY,
		1471	sub { } # just for the PERL_ASYNC_CHECK
		1472	;
1106	}	1473	}
1107	}	1474	}
1108		1475
1109	sub time { _time }	1476	sub _sig_del {
1110	sub now { _time }	1477	undef $SIG_TW
1111	sub now_update { }	1478	unless --$SIG_COUNT;
1112
1113	# default implementation for ->condvar
1114
1115	sub condvar {
1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1117	}	1479	}
1118		1480
1119	# default implementation for ->signal	1481	our $_sig_name_init; $_sig_name_init = sub {
		1482	eval q{ # poor man's autoloading {}
		1483	undef $_sig_name_init;
1120		1484
1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1485	if (_have_async_interrupt) {
		1486	*sig2num = \&Async::Interrupt::sig2num;
		1487	*sig2name = \&Async::Interrupt::sig2name;
		1488	} else {
		1489	require Config;
1122		1490
1123	sub _signal_exec {	1491	my %signame2num;
1124	sysread $SIGPIPE_R, my $dummy, 4;	1492	@signame2num{ split ' ', $Config::Config{sig_name} }
		1493	= split ' ', $Config::Config{sig_num};
1125		1494
1126	while (%SIG_EV) {	1495	my @signum2name;
1127	for (keys %SIG_EV) {	1496	@signum2name[values %signame2num] = keys %signame2num;
1128	delete $SIG_EV{$_};	1497
1129	$_->() for values %{ $SIG_CB{$_} || {} };	1498	*sig2num = sub($) {
		1499	$_[0] > 0 ? shift : $signame2num{+shift}
		1500	};
		1501	*sig2name = sub ($) {
		1502	$_[0] > 0 ? $signum2name[+shift] : shift
		1503	};
1130	}	1504	}
1131	}	1505	};
1132	}	1506	die if $@;
		1507	};
		1508
		1509	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1510	sub sig2name($) { &$_sig_name_init; &sig2name }
1133		1511
1134	sub signal {	1512	sub signal {
1135	my (undef, %arg) = @_;	1513	eval q{ # poor man's autoloading {}
		1514	# probe for availability of Async::Interrupt
		1515	if (_have_async_interrupt) {
		1516	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1136		1517
1137	unless ($SIGPIPE_R) {	1518	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1138	require Fcntl;	1519	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1139		1520
1140	if (AnyEvent::WIN32) {
1141	require AnyEvent::Util;
1142
1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1146	} else {	1521	} else {
		1522	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1523
		1524	if (AnyEvent::WIN32) {
		1525	require AnyEvent::Util;
		1526
		1527	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1528	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1529	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1530	} else {
1147	pipe $SIGPIPE_R, $SIGPIPE_W;	1531	pipe $SIGPIPE_R, $SIGPIPE_W;
1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1532	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1533	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1150		1534
1151	# not strictly required, as $^F is normally 2, but let's make sure...	1535	# not strictly required, as $^F is normally 2, but let's make sure...
1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1536	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1537	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1538	}
		1539
		1540	$SIGPIPE_R
		1541	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1542
		1543	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1154	}	1544	}
1155		1545
1156	$SIGPIPE_R	1546	*signal = $HAVE_ASYNC_INTERRUPT
1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1547	? sub {
		1548	my (undef, %arg) = @_;
1158		1549
1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1550	# async::interrupt
1160	}
1161
1162	my $signal = uc $arg{signal}	1551	my $signal = sig2num $arg{signal};
1163	or Carp::croak "required option 'signal' is missing";
1164
1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1552	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1553
		1554	$SIG_ASY{$signal} ||= new Async::Interrupt
		1555	cb => sub { undef $SIG_EV{$signal} },
		1556	signal => $signal,
		1557	pipe => [$SIGPIPE_R->filenos],
		1558	pipe_autodrain => 0,
		1559	;
		1560
		1561	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1562	}
		1563	: sub {
		1564	my (undef, %arg) = @_;
		1565
		1566	# pure perl
		1567	my $signal = sig2name $arg{signal};
		1568	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1569
1166	$SIG{$signal} ||= sub {	1570	$SIG{$signal} ||= sub {
1167	local $!;	1571	local $!;
1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1572	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1169	undef $SIG_EV{$signal};	1573	undef $SIG_EV{$signal};
		1574	};
		1575
		1576	# can't do signal processing without introducing races in pure perl,
		1577	# so limit the signal latency.
		1578	_sig_add;
		1579
		1580	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1581	}
		1582	;
		1583
		1584	*AnyEvent::Base::signal::DESTROY = sub {
		1585	my ($signal, $cb) = @{$_[0]};
		1586
		1587	_sig_del;
		1588
		1589	delete $SIG_CB{$signal}{$cb};
		1590
		1591	$HAVE_ASYNC_INTERRUPT
		1592	? delete $SIG_ASY{$signal}
		1593	: # delete doesn't work with older perls - they then
		1594	# print weird messages, or just unconditionally exit
		1595	# instead of getting the default action.
		1596	undef $SIG{$signal}
		1597	unless keys %{ $SIG_CB{$signal} };
		1598	};
		1599
		1600	*_signal_exec = sub {
		1601	$HAVE_ASYNC_INTERRUPT
		1602	? $SIGPIPE_R->drain
		1603	: sysread $SIGPIPE_R, (my $dummy), 9;
		1604
		1605	while (%SIG_EV) {
		1606	for (keys %SIG_EV) {
		1607	delete $SIG_EV{$_};
		1608	$_->() for values %{ $SIG_CB{$_} || {} };
		1609	}
		1610	}
		1611	};
1170	};	1612	};
		1613	die if $@;
1171		1614
1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1615	&signal
1173	}
1174
1175	sub AnyEvent::Base::signal::DESTROY {
1176	my ($signal, $cb) = @{$_[0]};
1177
1178	delete $SIG_CB{$signal}{$cb};
1179
1180	# delete doesn't work with older perls - they then
1181	# print weird messages, or just unconditionally exit
1182	# instead of getting the default action.
1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1184	}	1616	}
1185		1617
1186	# default implementation for ->child	1618	# default implementation for ->child
1187		1619
1188	our %PID_CB;	1620	our %PID_CB;
1189	our $CHLD_W;	1621	our $CHLD_W;
1190	our $CHLD_DELAY_W;	1622	our $CHLD_DELAY_W;
1191	our $WNOHANG;
1192		1623
1193	sub _sigchld {	1624	# used by many Impl's
1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1625	sub _emit_childstatus($$) {
		1626	my (undef, $rpid, $rstatus) = @_;
		1627
		1628	$_->($rpid, $rstatus)
1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1629	for values %{ $PID_CB{$rpid} || {} },
1196	(values %{ $PID_CB{0} || {} });	1630	values %{ $PID_CB{0} || {} };
1197	}
1198	}	1631	}
1199		1632
1200	sub child {	1633	sub child {
		1634	eval q{ # poor man's autoloading {}
		1635	*_sigchld = sub {
		1636	my $pid;
		1637
		1638	AnyEvent->_emit_childstatus ($pid, $?)
		1639	while ($pid = waitpid -1, WNOHANG) > 0;
		1640	};
		1641
		1642	*child = sub {
1201	my (undef, %arg) = @_;	1643	my (undef, %arg) = @_;
1202		1644
1203	defined (my $pid = $arg{pid} + 0)	1645	defined (my $pid = $arg{pid} + 0)
1204	or Carp::croak "required option 'pid' is missing";	1646	or Carp::croak "required option 'pid' is missing";
1205		1647
1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1648	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1207		1649
1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1209
1210	unless ($CHLD_W) {	1650	unless ($CHLD_W) {
1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1651	$CHLD_W = AE::signal CHLD => \&_sigchld;
1212	# child could be a zombie already, so make at least one round	1652	# child could be a zombie already, so make at least one round
1213	&_sigchld;	1653	&_sigchld;
1214	}	1654	}
1215		1655
1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1656	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1217	}	1657	};
1218		1658
1219	sub AnyEvent::Base::child::DESTROY {	1659	*AnyEvent::Base::child::DESTROY = sub {
1220	my ($pid, $cb) = @{$_[0]};	1660	my ($pid, $cb) = @{$_[0]};
1221		1661
1222	delete $PID_CB{$pid}{$cb};	1662	delete $PID_CB{$pid}{$cb};
1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1663	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1224		1664
1225	undef $CHLD_W unless keys %PID_CB;	1665	undef $CHLD_W unless keys %PID_CB;
		1666	};
		1667	};
		1668	die if $@;
		1669
		1670	&child
1226	}	1671	}
1227		1672
1228	# idle emulation is done by simply using a timer, regardless	1673	# idle emulation is done by simply using a timer, regardless
1229	# of whether the process is idle or not, and not letting	1674	# of whether the process is idle or not, and not letting
1230	# the callback use more than 50% of the time.	1675	# the callback use more than 50% of the time.
1231	sub idle {	1676	sub idle {
		1677	eval q{ # poor man's autoloading {}
		1678	*idle = sub {
1232	my (undef, %arg) = @_;	1679	my (undef, %arg) = @_;
1233		1680
1234	my ($cb, $w, $rcb) = $arg{cb};	1681	my ($cb, $w, $rcb) = $arg{cb};
1235		1682
1236	$rcb = sub {	1683	$rcb = sub {
1237	if ($cb) {	1684	if ($cb) {
1238	$w = _time;	1685	$w = _time;
1239	&$cb;	1686	&$cb;
1240	$w = _time - $w;	1687	$w = _time - $w;
1241		1688
1242	# never use more then 50% of the time for the idle watcher,	1689	# never use more then 50% of the time for the idle watcher,
1243	# within some limits	1690	# within some limits
1244	$w = 0.0001 if $w < 0.0001;	1691	$w = 0.0001 if $w < 0.0001;
1245	$w = 5 if $w > 5;	1692	$w = 5 if $w > 5;
1246		1693
1247	$w = AnyEvent->timer (after => $w, cb => $rcb);	1694	$w = AE::timer $w, 0, $rcb;
1248	} else {	1695	} else {
1249	# clean up...	1696	# clean up...
1250	undef $w;	1697	undef $w;
1251	undef $rcb;	1698	undef $rcb;
		1699	}
		1700	};
		1701
		1702	$w = AE::timer 0.05, 0, $rcb;
		1703
		1704	bless \\$cb, "AnyEvent::Base::idle"
1252	}	1705	};
		1706
		1707	*AnyEvent::Base::idle::DESTROY = sub {
		1708	undef $${$_[0]};
		1709	};
1253	};	1710	};
		1711	die if $@;
1254		1712
1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1713	&idle
1256
1257	bless \\$cb, "AnyEvent::Base::idle"
1258	}
1259
1260	sub AnyEvent::Base::idle::DESTROY {
1261	undef $${$_[0]};
1262	}	1714	}
1263		1715
1264	package AnyEvent::CondVar;	1716	package AnyEvent::CondVar;
1265		1717
1266	our @ISA = AnyEvent::CondVar::Base::;	1718	our @ISA = AnyEvent::CondVar::Base::;
1267		1719
		1720	# only to be used for subclassing
		1721	sub new {
		1722	my $class = shift;
		1723	bless AnyEvent->condvar (@_), $class
		1724	}
		1725
1268	package AnyEvent::CondVar::Base;	1726	package AnyEvent::CondVar::Base;
1269		1727
1270	use overload	1728	#use overload
1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1729	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1272	fallback => 1;	1730	# fallback => 1;
		1731
		1732	# save 300+ kilobytes by dirtily hardcoding overloading
		1733	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1734	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1735	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1736	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1737
		1738	our $WAITING;
1273		1739
1274	sub _send {	1740	sub _send {
1275	# nop	1741	# nop
		1742	}
		1743
		1744	sub _wait {
		1745	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
1276	}	1746	}
1277		1747
1278	sub send {	1748	sub send {
1279	my $cv = shift;	1749	my $cv = shift;
1280	$cv->{_ae_sent} = [@_];	1750	$cv->{_ae_sent} = [@_];
…		…
1289		1759
1290	sub ready {	1760	sub ready {
1291	$_[0]{_ae_sent}	1761	$_[0]{_ae_sent}
1292	}	1762	}
1293		1763
1294	sub _wait {
1295	AnyEvent->one_event while !$_[0]{_ae_sent};
1296	}
1297
1298	sub recv {	1764	sub recv {
		1765	unless ($_[0]{_ae_sent}) {
		1766	$WAITING
		1767	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1768
		1769	local $WAITING = 1;
1299	$_[0]->_wait;	1770	$_[0]->_wait;
		1771	}
1300		1772
1301	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1773	$_[0]{_ae_croak}
1302	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1774	and Carp::croak $_[0]{_ae_croak};
		1775
		1776	wantarray
		1777	? @{ $_[0]{_ae_sent} }
		1778	: $_[0]{_ae_sent}[0]
1303	}	1779	}
1304		1780
1305	sub cb {	1781	sub cb {
1306	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1782	my $cv = shift;
		1783
		1784	@_
		1785	and $cv->{_ae_cb} = shift
		1786	and $cv->{_ae_sent}
		1787	and (delete $cv->{_ae_cb})->($cv);
		1788
1307	$_[0]{_ae_cb}	1789	$cv->{_ae_cb}
1308	}	1790	}
1309		1791
1310	sub begin {	1792	sub begin {
1311	++$_[0]{_ae_counter};	1793	++$_[0]{_ae_counter};
1312	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1794	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1317	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1799	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1318	}	1800	}
1319		1801
1320	# undocumented/compatibility with pre-3.4	1802	# undocumented/compatibility with pre-3.4
1321	*broadcast = \&send;	1803	*broadcast = \&send;
1322	*wait = \&_wait;	1804	*wait = \&recv;
1323		1805
1324	=head1 ERROR AND EXCEPTION HANDLING	1806	=head1 ERROR AND EXCEPTION HANDLING
1325		1807
1326	In general, AnyEvent does not do any error handling - it relies on the	1808	In general, AnyEvent does not do any error handling - it relies on the
1327	caller to do that if required. The L<AnyEvent::Strict> module (see also	1809	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1361	C<PERL_ANYEVENT_MODEL>.	1843	C<PERL_ANYEVENT_MODEL>.
1362		1844
1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1845	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1364	model it chooses.	1846	model it chooses.
1365		1847
		1848	When set to C<8> or higher, then AnyEvent will report extra information on
		1849	which optional modules it loads and how it implements certain features.
		1850
1366	=item C<PERL_ANYEVENT_STRICT>	1851	=item C<PERL_ANYEVENT_STRICT>
1367		1852
1368	AnyEvent does not do much argument checking by default, as thorough	1853	AnyEvent does not do much argument checking by default, as thorough
1369	argument checking is very costly. Setting this variable to a true value	1854	argument checking is very costly. Setting this variable to a true value
1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1855	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1371	check the arguments passed to most method calls. If it finds any problems	1856	check the arguments passed to most method calls. If it finds any problems,
1372	it will croak.	1857	it will croak.
1373		1858
1374	In other words, enables "strict" mode.	1859	In other words, enables "strict" mode.
1375		1860
1376	Unlike C<use strict>, it is definitely recommended ot keep it off in	1861	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1862	>>, it is definitely recommended to keep it off in production. Keeping
1378	developing programs can be very useful, however.	1863	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1864	can be very useful, however.
1379		1865
1380	=item C<PERL_ANYEVENT_MODEL>	1866	=item C<PERL_ANYEVENT_MODEL>
1381		1867
1382	This can be used to specify the event model to be used by AnyEvent, before	1868	This can be used to specify the event model to be used by AnyEvent, before
1383	auto detection and -probing kicks in. It must be a string consisting	1869	auto detection and -probing kicks in. It must be a string consisting
…		…
1426		1912
1427	=item C<PERL_ANYEVENT_MAX_FORKS>	1913	=item C<PERL_ANYEVENT_MAX_FORKS>
1428		1914
1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1915	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1430	will create in parallel.	1916	will create in parallel.
		1917
		1918	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1919
		1920	The default value for the C<max_outstanding> parameter for the default DNS
		1921	resolver - this is the maximum number of parallel DNS requests that are
		1922	sent to the DNS server.
		1923
		1924	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1925
		1926	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1927	configuration) in the default resolver. When set to the empty string, no
		1928	default config will be used.
		1929
		1930	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1931
		1932	When neither C<ca_file> nor C<ca_path> was specified during
		1933	L<AnyEvent::TLS> context creation, and either of these environment
		1934	variables exist, they will be used to specify CA certificate locations
		1935	instead of a system-dependent default.
		1936
		1937	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1938
		1939	When these are set to C<1>, then the respective modules are not
		1940	loaded. Mostly good for testing AnyEvent itself.
1431		1941
1432	=back	1942	=back
1433		1943
1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1944	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1435		1945
…		…
1493	warn "read: $input\n"; # output what has been read	2003	warn "read: $input\n"; # output what has been read
1494	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2004	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1495	},	2005	},
1496	);	2006	);
1497		2007
1498	my $time_watcher; # can only be used once
1499
1500	sub new_timer {
1501	$timer = AnyEvent->timer (after => 1, cb => sub {	2008	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1502	warn "timeout\n"; # print 'timeout' about every second	2009	warn "timeout\n"; # print 'timeout' at most every second
1503	&new_timer; # and restart the time
1504	});	2010	});
1505	}
1506
1507	new_timer; # create first timer
1508		2011
1509	$cv->recv; # wait until user enters /^q/i	2012	$cv->recv; # wait until user enters /^q/i
1510		2013
1511	=head1 REAL-WORLD EXAMPLE	2014	=head1 REAL-WORLD EXAMPLE
1512		2015
…		…
1585		2088
1586	The actual code goes further and collects all errors (C<die>s, exceptions)	2089	The actual code goes further and collects all errors (C<die>s, exceptions)
1587	that occurred during request processing. The C<result> method detects	2090	that occurred during request processing. The C<result> method detects
1588	whether an exception as thrown (it is stored inside the $txn object)	2091	whether an exception as thrown (it is stored inside the $txn object)
1589	and just throws the exception, which means connection errors and other	2092	and just throws the exception, which means connection errors and other
1590	problems get reported tot he code that tries to use the result, not in a	2093	problems get reported to the code that tries to use the result, not in a
1591	random callback.	2094	random callback.
1592		2095
1593	All of this enables the following usage styles:	2096	All of this enables the following usage styles:
1594		2097
1595	1. Blocking:	2098	1. Blocking:
…		…
1643	through AnyEvent. The benchmark creates a lot of timers (with a zero	2146	through AnyEvent. The benchmark creates a lot of timers (with a zero
1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2147	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1645	which it is), lets them fire exactly once and destroys them again.	2148	which it is), lets them fire exactly once and destroys them again.
1646		2149
1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2150	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1648	distribution.	2151	distribution. It uses the L<AE> interface, which makes a real difference
		2152	for the EV and Perl backends only.
1649		2153
1650	=head3 Explanation of the columns	2154	=head3 Explanation of the columns
1651		2155
1652	I<watcher> is the number of event watchers created/destroyed. Since	2156	I<watcher> is the number of event watchers created/destroyed. Since
1653	different event models feature vastly different performances, each event	2157	different event models feature vastly different performances, each event
…		…
1674	watcher.	2178	watcher.
1675		2179
1676	=head3 Results	2180	=head3 Results
1677		2181
1678	name watchers bytes create invoke destroy comment	2182	name watchers bytes create invoke destroy comment
1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2183	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2184	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2185	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2186	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2187	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2188	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2189	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2190	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2191	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2192	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2193	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2194	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1689		2195
1690	=head3 Discussion	2196	=head3 Discussion
1691		2197
1692	The benchmark does I<not> measure scalability of the event loop very	2198	The benchmark does I<not> measure scalability of the event loop very
1693	well. For example, a select-based event loop (such as the pure perl one)	2199	well. For example, a select-based event loop (such as the pure perl one)
…		…
1705	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2211	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1706	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2212	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1707	cycles with POE.	2213	cycles with POE.
1708		2214
1709	C<EV> is the sole leader regarding speed and memory use, which are both	2215	C<EV> is the sole leader regarding speed and memory use, which are both
1710	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2216	maximal/minimal, respectively. When using the L<AE> API there is zero
		2217	overhead (when going through the AnyEvent API create is about 5-6 times
		2218	slower, with other times being equal, so still uses far less memory than
1711	far less memory than any other event loop and is still faster than Event	2219	any other event loop and is still faster than Event natively).
1712	natively.
1713		2220
1714	The pure perl implementation is hit in a few sweet spots (both the	2221	The pure perl implementation is hit in a few sweet spots (both the
1715	constant timeout and the use of a single fd hit optimisations in the perl	2222	constant timeout and the use of a single fd hit optimisations in the perl
1716	interpreter and the backend itself). Nevertheless this shows that it	2223	interpreter and the backend itself). Nevertheless this shows that it
1717	adds very little overhead in itself. Like any select-based backend its	2224	adds very little overhead in itself. Like any select-based backend its
1718	performance becomes really bad with lots of file descriptors (and few of	2225	performance becomes really bad with lots of file descriptors (and few of
1719	them active), of course, but this was not subject of this benchmark.	2226	them active), of course, but this was not subject of this benchmark.
1720		2227
1721	The C<Event> module has a relatively high setup and callback invocation	2228	The C<Event> module has a relatively high setup and callback invocation
1722	cost, but overall scores in on the third place.	2229	cost, but overall scores in on the third place.
		2230
		2231	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2232	when using its pure perl backend.
1723		2233
1724	C<Glib>'s memory usage is quite a bit higher, but it features a	2234	C<Glib>'s memory usage is quite a bit higher, but it features a
1725	faster callback invocation and overall ends up in the same class as	2235	faster callback invocation and overall ends up in the same class as
1726	C<Event>. However, Glib scales extremely badly, doubling the number of	2236	C<Event>. However, Glib scales extremely badly, doubling the number of
1727	watchers increases the processing time by more than a factor of four,	2237	watchers increases the processing time by more than a factor of four,
…		…
1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2298	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1789	(1%) are active. This mirrors the activity of large servers with many	2299	(1%) are active. This mirrors the activity of large servers with many
1790	connections, most of which are idle at any one point in time.	2300	connections, most of which are idle at any one point in time.
1791		2301
1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2302	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1793	distribution.	2303	distribution. It uses the L<AE> interface, which makes a real difference
		2304	for the EV and Perl backends only.
1794		2305
1795	=head3 Explanation of the columns	2306	=head3 Explanation of the columns
1796		2307
1797	I<sockets> is the number of sockets, and twice the number of "servers" (as	2308	I<sockets> is the number of sockets, and twice the number of "servers" (as
1798	each server has a read and write socket end).	2309	each server has a read and write socket end).
…		…
1805	it to another server. This includes deleting the old timeout and creating	2316	it to another server. This includes deleting the old timeout and creating
1806	a new one that moves the timeout into the future.	2317	a new one that moves the timeout into the future.
1807		2318
1808	=head3 Results	2319	=head3 Results
1809		2320
1810	name sockets create request	2321	name sockets create request
1811	EV 20000 69.01 11.16	2322	EV 20000 62.66 7.99
1812	Perl 20000 73.32 35.87	2323	Perl 20000 68.32 32.64
1813	Event 20000 212.62 257.32	2324	IOAsync 20000 174.06 101.15 epoll
1814	Glib 20000 651.16 1896.30	2325	IOAsync 20000 174.67 610.84 poll
		2326	Event 20000 202.69 242.91
		2327	Glib 20000 557.01 1689.52
1815	POE 20000 349.67 12317.24 uses POE::Loop::Event	2328	POE 20000 341.54 12086.32 uses POE::Loop::Event
1816		2329
1817	=head3 Discussion	2330	=head3 Discussion
1818		2331
1819	This benchmark I<does> measure scalability and overall performance of the	2332	This benchmark I<does> measure scalability and overall performance of the
1820	particular event loop.	2333	particular event loop.
…		…
1822	EV is again fastest. Since it is using epoll on my system, the setup time	2335	EV is again fastest. Since it is using epoll on my system, the setup time
1823	is relatively high, though.	2336	is relatively high, though.
1824		2337
1825	Perl surprisingly comes second. It is much faster than the C-based event	2338	Perl surprisingly comes second. It is much faster than the C-based event
1826	loops Event and Glib.	2339	loops Event and Glib.
		2340
		2341	IO::Async performs very well when using its epoll backend, and still quite
		2342	good compared to Glib when using its pure perl backend.
1827		2343
1828	Event suffers from high setup time as well (look at its code and you will	2344	Event suffers from high setup time as well (look at its code and you will
1829	understand why). Callback invocation also has a high overhead compared to	2345	understand why). Callback invocation also has a high overhead compared to
1830	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2346	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1831	uses select or poll in basically all documented configurations.	2347	uses select or poll in basically all documented configurations.
…		…
1900		2416
1901	Recently I was told about the benchmark in the IO::Lambda manpage, which	2417	Recently I was told about the benchmark in the IO::Lambda manpage, which
1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark	2418	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which	2419	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
1904	shouldn't come as a surprise to anybody). As such, the benchmark is	2420	shouldn't come as a surprise to anybody). As such, the benchmark is
1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very	2421	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
1906	optimal. But how would AnyEvent compare when used without the extra	2422	very optimal. But how would AnyEvent compare when used without the extra
1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.	2423	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
1908		2424
1909	The benchmark itself creates an echo-server, and then, for 500 times,	2425	The benchmark itself creates an echo-server, and then, for 500 times,
1910	connects to the echo server, sends a line, waits for the reply, and then	2426	connects to the echo server, sends a line, waits for the reply, and then
1911	creates the next connection. This is a rather bad benchmark, as it doesn't	2427	creates the next connection. This is a rather bad benchmark, as it doesn't
1912	test the efficiency of the framework, but it is a benchmark nevertheless.	2428	test the efficiency of the framework or much non-blocking I/O, but it is a
		2429	benchmark nevertheless.
1913		2430
1914	name runtime	2431	name runtime
1915	Lambda/select 0.330 sec	2432	Lambda/select 0.330 sec
1916	+ optimized 0.122 sec	2433	+ optimized 0.122 sec
1917	Lambda/AnyEvent 0.327 sec	2434	Lambda/AnyEvent 0.327 sec
…		…
1923		2440
1924	AnyEvent/select/nb 0.085 sec	2441	AnyEvent/select/nb 0.085 sec
1925	AnyEvent/EV/nb 0.068 sec	2442	AnyEvent/EV/nb 0.068 sec
1926	+state machine 0.134 sec	2443	+state machine 0.134 sec
1927		2444
1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda	2445	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1929	benchmarks actually make blocking connects and use 100% blocking I/O,	2446	benchmarks actually make blocking connects and use 100% blocking I/O,
1930	defeating the purpose of an event-based solution. All of the newly	2447	defeating the purpose of an event-based solution. All of the newly
1931	written AnyEvent benchmarks use 100% non-blocking connects (using	2448	written AnyEvent benchmarks use 100% non-blocking connects (using
1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS	2449	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects	2450	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
1934	generally require a lot more bookkeeping and event handling than blocking	2451	generally require a lot more bookkeeping and event handling than blocking
1935	connects (which involve a single syscall only).	2452	connects (which involve a single syscall only).
1936		2453
1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which	2454	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
1938	offers similar expressive power as POE and IO::Lambda (using conventional	2455	offers similar expressive power as POE and IO::Lambda, using conventional
1939	Perl syntax), which means both the echo server and the client are 100%	2456	Perl syntax. This means that both the echo server and the client are 100%
1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.	2457	non-blocking, further placing it at a disadvantage.
1941		2458
1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets	2459	As you can see, the AnyEvent + EV combination even beats the
1943	benchmark", while AnyEvent + its pure perl backend easily beats	2460	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1944	IO::Lambda and POE.	2461	backend easily beats IO::Lambda and POE.
1945		2462
1946	And even the 100% non-blocking version written using the high-level (and	2463	And even the 100% non-blocking version written using the high-level (and
1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,	2464	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2465	higher level ("unoptimised") abstractions by a large margin, even though
1948	even thought it does all of DNS, tcp-connect and socket I/O in a	2466	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1949	non-blocking way.	2467
		2468	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2469	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2470	part of the IO::Lambda distribution and were used without any changes.
1950		2471
1951		2472
1952	=head1 SIGNALS	2473	=head1 SIGNALS
1953		2474
1954	AnyEvent currently installs handlers for these signals:	2475	AnyEvent currently installs handlers for these signals:
…		…
1958	=item SIGCHLD	2479	=item SIGCHLD
1959		2480
1960	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2481	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1961	emulation for event loops that do not support them natively. Also, some	2482	emulation for event loops that do not support them natively. Also, some
1962	event loops install a similar handler.	2483	event loops install a similar handler.
		2484
		2485	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2486	AnyEvent will reset it to default, to avoid losing child exit statuses.
1963		2487
1964	=item SIGPIPE	2488	=item SIGPIPE
1965		2489
1966	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2490	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1967	when AnyEvent gets loaded.	2491	when AnyEvent gets loaded.
…		…
1979		2503
1980	=back	2504	=back
1981		2505
1982	=cut	2506	=cut
1983		2507
		2508	undef $SIG{CHLD}
		2509	if $SIG{CHLD} eq 'IGNORE';
		2510
1984	$SIG{PIPE} = sub { }	2511	$SIG{PIPE} = sub { }
1985	unless defined $SIG{PIPE};	2512	unless defined $SIG{PIPE};
1986		2513
		2514	=head1 RECOMMENDED/OPTIONAL MODULES
		2515
		2516	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2517	its built-in modules) are required to use it.
		2518
		2519	That does not mean that AnyEvent won't take advantage of some additional
		2520	modules if they are installed.
		2521
		2522	This section explains which additional modules will be used, and how they
		2523	affect AnyEvent's operation.
		2524
		2525	=over 4
		2526
		2527	=item L<Async::Interrupt>
		2528
		2529	This slightly arcane module is used to implement fast signal handling: To
		2530	my knowledge, there is no way to do completely race-free and quick
		2531	signal handling in pure perl. To ensure that signals still get
		2532	delivered, AnyEvent will start an interval timer to wake up perl (and
		2533	catch the signals) with some delay (default is 10 seconds, look for
		2534	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2535
		2536	If this module is available, then it will be used to implement signal
		2537	catching, which means that signals will not be delayed, and the event loop
		2538	will not be interrupted regularly, which is more efficient (and good for
		2539	battery life on laptops).
		2540
		2541	This affects not just the pure-perl event loop, but also other event loops
		2542	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2543
		2544	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2545	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2546	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2547	does nothing for those backends.
		2548
		2549	=item L<EV>
		2550
		2551	This module isn't really "optional", as it is simply one of the backend
		2552	event loops that AnyEvent can use. However, it is simply the best event
		2553	loop available in terms of features, speed and stability: It supports
		2554	the AnyEvent API optimally, implements all the watcher types in XS, does
		2555	automatic timer adjustments even when no monotonic clock is available,
		2556	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2557	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2558	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2559
		2560	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2561	then this module will do nothing for you.
		2562
		2563	=item L<Guard>
		2564
		2565	The guard module, when used, will be used to implement
		2566	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2567	lot less memory), but otherwise doesn't affect guard operation much. It is
		2568	purely used for performance.
		2569
		2570	=item L<JSON> and L<JSON::XS>
		2571
		2572	One of these modules is required when you want to read or write JSON data
		2573	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2574	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2575
		2576	=item L<Net::SSLeay>
		2577
		2578	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2579	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2580	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2581
		2582	=item L<Time::HiRes>
		2583
		2584	This module is part of perl since release 5.008. It will be used when the
		2585	chosen event library does not come with a timing source of its own. The
		2586	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2587	try to use a monotonic clock for timing stability.
		2588
		2589	=back
		2590
1987		2591
1988	=head1 FORK	2592	=head1 FORK
1989		2593
1990	Most event libraries are not fork-safe. The ones who are usually are	2594	Most event libraries are not fork-safe. The ones who are usually are
1991	because they rely on inefficient but fork-safe C<select> or C<poll>	2595	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1992	calls. Only L<EV> is fully fork-aware.	2596	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2597	are usually badly thought-out hacks that are incompatible with fork in
		2598	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2599	continue event-processing in both parent and child (or both, if you know
		2600	what you are doing).
		2601
		2602	This means that, in general, you cannot fork and do event processing in
		2603	the child if the event library was initialised before the fork (which
		2604	usually happens when the first AnyEvent watcher is created, or the library
		2605	is loaded).
1993		2606
1994	If you have to fork, you must either do so I<before> creating your first	2607	If you have to fork, you must either do so I<before> creating your first
1995	watcher OR you must not use AnyEvent at all in the child.	2608	watcher OR you must not use AnyEvent at all in the child OR you must do
		2609	something completely out of the scope of AnyEvent.
		2610
		2611	The problem of doing event processing in the parent I<and> the child
		2612	is much more complicated: even for backends that I<are> fork-aware or
		2613	fork-safe, their behaviour is not usually what you want: fork clones all
		2614	watchers, that means all timers, I/O watchers etc. are active in both
		2615	parent and child, which is almost never what you want. USing C<exec>
		2616	to start worker children from some kind of manage rprocess is usually
		2617	preferred, because it is much easier and cleaner, at the expense of having
		2618	to have another binary.
1996		2619
1997		2620
1998	=head1 SECURITY CONSIDERATIONS	2621	=head1 SECURITY CONSIDERATIONS
1999		2622
2000	AnyEvent can be forced to load any event model via	2623	AnyEvent can be forced to load any event model via
…		…
2014	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2637	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
2015	be used to probe what backend is used and gain other information (which is	2638	be used to probe what backend is used and gain other information (which is
2016	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2639	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
2017	$ENV{PERL_ANYEVENT_STRICT}.	2640	$ENV{PERL_ANYEVENT_STRICT}.
2018		2641
		2642	Note that AnyEvent will remove I<all> environment variables starting with
		2643	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2644	enabled.
		2645
2019		2646
2020	=head1 BUGS	2647	=head1 BUGS
2021		2648
2022	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2649	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
2023	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2650	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
…		…
2026	pronounced).	2653	pronounced).
2027		2654
2028		2655
2029	=head1 SEE ALSO	2656	=head1 SEE ALSO
2030		2657
		2658	Tutorial/Introduction: L<AnyEvent::Intro>.
		2659
		2660	FAQ: L<AnyEvent::FAQ>.
		2661
2031	Utility functions: L<AnyEvent::Util>.	2662	Utility functions: L<AnyEvent::Util>.
2032		2663
2033	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2664	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
2034	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2665	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2035		2666
2036	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2667	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2037	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2668	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2038	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2669	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2039	L<AnyEvent::Impl::POE>.	2670	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2040		2671
2041	Non-blocking file handles, sockets, TCP clients and	2672	Non-blocking file handles, sockets, TCP clients and
2042	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2673	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2043		2674
2044	Asynchronous DNS: L<AnyEvent::DNS>.	2675	Asynchronous DNS: L<AnyEvent::DNS>.
2045		2676
2046	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2677	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
2047		2678
2048	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2679	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2680	L<AnyEvent::HTTP>.
2049		2681
2050		2682
2051	=head1 AUTHOR	2683	=head1 AUTHOR
2052		2684
2053	Marc Lehmann <schmorp@schmorp.de>	2685	Marc Lehmann <schmorp@schmorp.de>

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