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Revision 1.332 by root, Tue Aug 31 23:32:40 2010 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	There is a mailinglist for discussing all things AnyEvent, and an IRC
		52	channel, too.
		53
		54	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		55	Repository>, at L<http://anyevent.schmorp.de>, for more info.
45		56
46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	57	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
47		58
48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	59	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
49	nowadays. So what is different about AnyEvent?	60	nowadays. So what is different about AnyEvent?
…		…
65	module users into the same thing by forcing them to use the same event	76	module users into the same thing by forcing them to use the same event
66	model you use.	77	model you use.
67		78
68	For modules like POE or IO::Async (which is a total misnomer as it is	79	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	80	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	81	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	82	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	83	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.	84	module are I<also> forced to use the same event loop you use.
74		85
75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	87	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	88	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
78	your module uses one of those, every user of your module has to use it,	89	your module uses one of those, every user of your module has to use it,
79	too. But if your module uses AnyEvent, it works transparently with all	90	too. But if your module uses AnyEvent, it works transparently with all
80	event models it supports (including stuff like IO::Async, as long as those	91	event models it supports (including stuff like IO::Async, as long as those
81	use one of the supported event loops. It is trivial to add new event loops	92	use one of the supported event loops. It is easy to add new event loops
82	to AnyEvent, too, so it is future-proof).	93	to AnyEvent, too, so it is future-proof).
83		94
84	In addition to being free of having to use I<the one and only true event	95	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	96	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	97	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	98	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	99	offering the functionality that is necessary, in as thin as a wrapper as
89	technically possible.	100	technically possible.
90		101
91	Of course, AnyEvent comes with a big (and fully optional!) toolbox	102	Of course, AnyEvent comes with a big (and fully optional!) toolbox
92	of useful functionality, such as an asynchronous DNS resolver, 100%	103	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	109	useful) and you want to force your users to use the one and only event
99	model, you should I<not> use this module.	110	model, you should I<not> use this module.
100		111
101	=head1 DESCRIPTION	112	=head1 DESCRIPTION
102		113
103	L<AnyEvent> provides an identical interface to multiple event loops. This	114	L<AnyEvent> provides a uniform interface to various event loops. This
104	allows module authors to utilise an event loop without forcing module	115	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	116	module users to use a specific event loop implementation (since more
106	peacefully at any one time).	117	than one event loop cannot coexist peacefully).
107		118
108	The interface itself is vaguely similar, but not identical to the L<Event>	119	The interface itself is vaguely similar, but not identical to the L<Event>
109	module.	120	module.
110		121
111	During the first call of any watcher-creation method, the module tries	122	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	123	to detect the currently loaded event loop by probing whether one of the
113	following modules is already loaded: L<EV>,	124	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>,	125	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	126	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	127	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	128	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	129	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		130
122	Because AnyEvent first checks for modules that are already loaded, loading	131	Because AnyEvent first checks for modules that are already loaded, loading
123	an event model explicitly before first using AnyEvent will likely make	132	an event model explicitly before first using AnyEvent will likely make
124	that model the default. For example:	133	that model the default. For example:
125		134
…		…
127	use AnyEvent;	136	use AnyEvent;
128		137
129	# .. AnyEvent will likely default to Tk	138	# .. AnyEvent will likely default to Tk
130		139
131	The I<likely> means that, if any module loads another event model and	140	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	141	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...	142	as very few modules hardcode event loops without announcing this very
		143	loudly.
134		144
135	The pure-perl implementation of AnyEvent is called	145	The pure-perl implementation of AnyEvent is called
136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	146	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
137	explicitly and enjoy the high availability of that event loop :)	147	explicitly and enjoy the high availability of that event loop :)
138		148
…		…
147	callback when the event occurs (of course, only when the event model	157	callback when the event occurs (of course, only when the event model
148	is in control).	158	is in control).
149		159
150	Note that B<callbacks must not permanently change global variables>	160	Note that B<callbacks must not permanently change global variables>
151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	161	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
152	callbacks must not C<die> >>. The former is good programming practise in	162	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	163	Perl and the latter stems from the fact that exception handling differs
154	widely between event loops.	164	widely between event loops.
155		165
156	To disable the watcher you have to destroy it (e.g. by setting the	166	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	167	variable you store it in to C<undef> or otherwise deleting all references
158	to it).	168	to it).
159		169
160	All watchers are created by calling a method on the C<AnyEvent> class.	170	All watchers are created by calling a method on the C<AnyEvent> class.
161		171
162	Many watchers either are used with "recursion" (repeating timers for	172	Many watchers either are used with "recursion" (repeating timers for
163	example), or need to refer to their watcher object in other ways.	173	example), or need to refer to their watcher object in other ways.
164		174
165	An any way to achieve that is this pattern:	175	One way to achieve that is this pattern:
166		176
167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	177	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
168	# you can use $w here, for example to undef it	178	# you can use $w here, for example to undef it
169	undef $w;	179	undef $w;
170	});	180	});
…		…
172	Note that C<my $w; $w => combination. This is necessary because in Perl,	182	Note that C<my $w; $w => combination. This is necessary because in Perl,
173	my variables are only visible after the statement in which they are	183	my variables are only visible after the statement in which they are
174	declared.	184	declared.
175		185
176	=head2 I/O WATCHERS	186	=head2 I/O WATCHERS
		187
		188	$w = AnyEvent->io (
		189	fh => <filehandle_or_fileno>,
		190	poll => <"r" or "w">,
		191	cb => <callback>,
		192	);
177		193
178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	194	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
179	with the following mandatory key-value pairs as arguments:	195	with the following mandatory key-value pairs as arguments:
180		196
181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch	197	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
…		…
196		212
197	The I/O watcher might use the underlying file descriptor or a copy of it.	213	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	214	You must not close a file handle as long as any watcher is active on the
199	underlying file descriptor.	215	underlying file descriptor.
200		216
201	Some event loops issue spurious readyness notifications, so you should	217	Some event loops issue spurious readiness notifications, so you should
202	always use non-blocking calls when reading/writing from/to your file	218	always use non-blocking calls when reading/writing from/to your file
203	handles.	219	handles.
204		220
205	Example: wait for readability of STDIN, then read a line and disable the	221	Example: wait for readability of STDIN, then read a line and disable the
206	watcher.	222	watcher.
…		…
211	undef $w;	227	undef $w;
212	});	228	});
213		229
214	=head2 TIME WATCHERS	230	=head2 TIME WATCHERS
215		231
		232	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		233
		234	$w = AnyEvent->timer (
		235	after => <fractional_seconds>,
		236	interval => <fractional_seconds>,
		237	cb => <callback>,
		238	);
		239
216	You can create a time watcher by calling the C<< AnyEvent->timer >>	240	You can create a time watcher by calling the C<< AnyEvent->timer >>
217	method with the following mandatory arguments:	241	method with the following mandatory arguments:
218		242
219	C<after> specifies after how many seconds (fractional values are	243	C<after> specifies after how many seconds (fractional values are
220	supported) the callback should be invoked. C<cb> is the callback to invoke	244	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
222		246
223	Although the callback might get passed parameters, their value and	247	Although the callback might get passed parameters, their value and
224	presence is undefined and you cannot rely on them. Portable AnyEvent	248	presence is undefined and you cannot rely on them. Portable AnyEvent
225	callbacks cannot use arguments passed to time watcher callbacks.	249	callbacks cannot use arguments passed to time watcher callbacks.
226		250
227	The callback will normally be invoked once only. If you specify another	251	The callback will normally be invoked only once. If you specify another
228	parameter, C<interval>, as a strictly positive number (> 0), then the	252	parameter, C<interval>, as a strictly positive number (> 0), then the
229	callback will be invoked regularly at that interval (in fractional	253	callback will be invoked regularly at that interval (in fractional
230	seconds) after the first invocation. If C<interval> is specified with a	254	seconds) after the first invocation. If C<interval> is specified with a
231	false value, then it is treated as if it were missing.	255	false value, then it is treated as if it were not specified at all.
232		256
233	The callback will be rescheduled before invoking the callback, but no	257	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	258	attempt is made to avoid timer drift in most backends, so the interval is
235	only approximate.	259	only approximate.
236		260
237	Example: fire an event after 7.7 seconds.	261	Example: fire an event after 7.7 seconds.
238		262
239	my $w = AnyEvent->timer (after => 7.7, cb => sub {	263	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
257		281
258	While most event loops expect timers to specified in a relative way, they	282	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	283	use absolute time internally. This makes a difference when your clock
260	"jumps", for example, when ntp decides to set your clock backwards from	284	"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	285	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.	286	fire "after a second" might actually take six years to finally fire.
263		287
264	AnyEvent cannot compensate for this. The only event loop that is conscious	288	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	289	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)	290	on true relative time) and absolute (ev_periodic, based on wallclock time)
267	timers.	291	timers.
268		292
269	AnyEvent always prefers relative timers, if available, matching the	293	AnyEvent always prefers relative timers, if available, matching the
270	AnyEvent API.	294	AnyEvent API.
…		…
292	I<In almost all cases (in all cases if you don't care), this is the	316	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.>	317	function to call when you want to know the current time.>
294		318
295	This function is also often faster then C<< AnyEvent->time >>, and	319	This function is also often faster then C<< AnyEvent->time >>, and
296	thus the preferred method if you want some timestamp (for example,	320	thus the preferred method if you want some timestamp (for example,
297	L<AnyEvent::Handle> uses this to update it's activity timeouts).	321	L<AnyEvent::Handle> uses this to update its activity timeouts).
298		322
299	The rest of this section is only of relevance if you try to be very exact	323	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.	324	with your timing; you can skip it without a bad conscience.
301		325
302	For a practical example of when these times differ, consider L<Event::Lib>	326	For a practical example of when these times differ, consider L<Event::Lib>
303	and L<EV> and the following set-up:	327	and L<EV> and the following set-up:
304		328
305	The event loop is running and has just invoked one of your callback at	329	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,	330	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	331	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	332	second) and then (at time=501) you create a relative timer that fires
309	after three seconds.	333	after three seconds.
310		334
…		…
341	might affect timers and time-outs.	365	might affect timers and time-outs.
342		366
343	When this is the case, you can call this method, which will update the	367	When this is the case, you can call this method, which will update the
344	event loop's idea of "current time".	368	event loop's idea of "current time".
345		369
		370	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		371	when mod_perl executes the script, then the event loop will have the wrong
		372	idea about the "current time" (being potentially far in the past, when the
		373	script ran the last time). In that case you should arrange a call to C<<
		374	AnyEvent->now_update >> each time the web server process wakes up again
		375	(e.g. at the start of your script, or in a handler).
		376
346	Note that updating the time I<might> cause some events to be handled.	377	Note that updating the time I<might> cause some events to be handled.
347		378
348	=back	379	=back
349		380
350	=head2 SIGNAL WATCHERS	381	=head2 SIGNAL WATCHERS
		382
		383	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
351		384
352	You can watch for signals using a signal watcher, C<signal> is the signal	385	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	386	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
354	callback to be invoked whenever a signal occurs.	387	callback to be invoked whenever a signal occurs.
355		388
…		…
361	invocation, and callback invocation will be synchronous. Synchronous means	394	invocation, and callback invocation will be synchronous. Synchronous means
362	that it might take a while until the signal gets handled by the process,	395	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.	396	but it is guaranteed not to interrupt any other callbacks.
364		397
365	The main advantage of using these watchers is that you can share a signal	398	The main advantage of using these watchers is that you can share a signal
366	between multiple watchers.	399	between multiple watchers, and AnyEvent will ensure that signals will not
		400	interrupt your program at bad times.
367		401
368	This watcher might use C<%SIG>, so programs overwriting those signals	402	This watcher might use C<%SIG> (depending on the event loop used),
369	directly will likely not work correctly.	403	so programs overwriting those signals directly will likely not work
		404	correctly.
370		405
371	Example: exit on SIGINT	406	Example: exit on SIGINT
372		407
373	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	408	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
374		409
		410	=head3 Restart Behaviour
		411
		412	While restart behaviour is up to the event loop implementation, most will
		413	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		414	pure perl implementation).
		415
		416	=head3 Safe/Unsafe Signals
		417
		418	Perl signals can be either "safe" (synchronous to opcode handling) or
		419	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		420	latter might corrupt your memory.
		421
		422	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		423	i.e. they will not interrupt your running perl program but will only be
		424	called as part of the normal event handling (just like timer, I/O etc.
		425	callbacks, too).
		426
		427	=head3 Signal Races, Delays and Workarounds
		428
		429	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		430	callbacks to signals in a generic way, which is a pity, as you cannot
		431	do race-free signal handling in perl, requiring C libraries for
		432	this. AnyEvent will try to do its best, which means in some cases,
		433	signals will be delayed. The maximum time a signal might be delayed is
		434	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		435	variable can be changed only before the first signal watcher is created,
		436	and should be left alone otherwise. This variable determines how often
		437	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		438	will cause fewer spurious wake-ups, which is better for power and CPU
		439	saving.
		440
		441	All these problems can be avoided by installing the optional
		442	L<Async::Interrupt> module, which works with most event loops. It will not
		443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		444	(and not with L<POE> currently, as POE does its own workaround with
		445	one-second latency). For those, you just have to suffer the delays.
		446
375	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
376		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
377	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
378		452
379	The child process is specified by the C<pid> argument (if set to C<0>, it	453	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	454	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	455	croak). The watcher will be triggered only when the child process has
382	any trace events (stopped/continued).	456	finished and an exit status is available, not on any trace events
		457	(stopped/continued).
383		458
384	The callback will be called with the pid and exit status (as returned by	459	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	460	waitpid), so unlike other watcher types, you I<can> rely on child watcher
386	callback arguments.	461	callback arguments.
387		462
…		…
403		478
404	This means you cannot create a child watcher as the very first	479	This means you cannot create a child watcher as the very first
405	thing in an AnyEvent program, you I<have> to create at least one	480	thing in an AnyEvent program, you I<have> to create at least one
406	watcher before you C<fork> the child (alternatively, you can call	481	watcher before you C<fork> the child (alternatively, you can call
407	C<AnyEvent::detect>).	482	C<AnyEvent::detect>).
		483
		484	As most event loops do not support waiting for child events, they will be
		485	emulated by AnyEvent in most cases, in which the latency and race problems
		486	mentioned in the description of signal watchers apply.
408		487
409	Example: fork a process and wait for it	488	Example: fork a process and wait for it
410		489
411	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
412		491
…		…
424	# do something else, then wait for process exit	503	# do something else, then wait for process exit
425	$done->recv;	504	$done->recv;
426		505
427	=head2 IDLE WATCHERS	506	=head2 IDLE WATCHERS
428		507
429	Sometimes there is a need to do something, but it is not so important	508	$w = AnyEvent->idle (cb => <callback>);
430	to do it instantly, but only when there is nothing better to do. This
431	"nothing better to do" is usually defined to be "no other events need
432	attention by the event loop".
433		509
434	Idle watchers ideally get invoked when the event loop has nothing	510	This will repeatedly invoke the callback after the process becomes idle,
435	better to do, just before it would block the process to wait for new	511	until either the watcher is destroyed or new events have been detected.
436	events. Instead of blocking, the idle watcher is invoked.
437		512
438	Most event loops unfortunately do not really support idle watchers (only	513	Idle watchers are useful when there is a need to do something, but it
		514	is not so important (or wise) to do it instantly. The callback will be
		515	invoked only when there is "nothing better to do", which is usually
		516	defined as "all outstanding events have been handled and no new events
		517	have been detected". That means that idle watchers ideally get invoked
		518	when the event loop has just polled for new events but none have been
		519	detected. Instead of blocking to wait for more events, the idle watchers
		520	will be invoked.
		521
		522	Unfortunately, most event loops do not really support idle watchers (only
439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	523	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
440	will simply call the callback "from time to time".	524	will simply call the callback "from time to time".
441		525
442	Example: read lines from STDIN, but only process them when the	526	Example: read lines from STDIN, but only process them when the
443	program is otherwise idle:	527	program is otherwise idle:
…		…
459	});	543	});
460	});	544	});
461		545
462	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
463		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
		552
464	If you are familiar with some event loops you will know that all of them	553	If you are familiar with some event loops you will know that all of them
465	require you to run some blocking "loop", "run" or similar function that	554	require you to run some blocking "loop", "run" or similar function that
466	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
467		556
468	AnyEvent is slightly different: it expects somebody else to run the event	557	AnyEvent is slightly different: it expects somebody else to run the event
469	loop and will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
470		559
471	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
472	because they represent a condition that must become true.	561	they represent a condition that must become true.
473		562
474	Now is probably a good time to look at the examples further below.	563	Now is probably a good time to look at the examples further below.
475		564
476	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
477	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
…		…
482	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
483	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
484	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
485	->send >> method).	574	->send >> method).
486		575
487	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
488	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
489	in time where multiple outstanding events have been processed. And yet	578
490	another way to call them is transactions - each condition variable can be	579	=over 4
491	used to represent a transaction, which finishes at some point and delivers	580
492	a result.	581	=item * Condition variables are like callbacks - you can call them (and pass them instead
		582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
493		599
494	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
495	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
496	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
497	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
510		616
511	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
512	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
513	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
514	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
515	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
516		622
517	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
518	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
519	for the send to occur.	625	for the send to occur.
520		626
521	Example: wait for a timer.	627	Example: wait for a timer.
522		628
523	# wait till the result is ready	629	# condition: "wait till the timer is fired"
524	my $result_ready = AnyEvent->condvar;	630	my $timer_fired = AnyEvent->condvar;
525		631
526	# do something such as adding a timer	632	# create the timer - we could wait for, say
527	# or socket watcher the calls $result_ready->send	633	# a handle becomign ready, or even an
528	# when the "result" is ready.	634	# AnyEvent::HTTP request to finish, but
529	# in this case, we simply use a timer:	635	# in this case, we simply use a timer:
530	my $w = AnyEvent->timer (	636	my $w = AnyEvent->timer (
531	after => 1,	637	after => 1,
532	cb => sub { $result_ready->send },	638	cb => sub { $timer_fired->send },
533	);	639	);
534		640
535	# this "blocks" (while handling events) till the callback	641	# this "blocks" (while handling events) till the callback
536	# calls -<send	642	# calls ->send
537	$result_ready->recv;	643	$timer_fired->recv;
538		644
539	Example: wait for a timer, but take advantage of the fact that condition	645	Example: wait for a timer, but take advantage of the fact that condition
540	variables are also callable directly.	646	variables are also callable directly.
541		647
542	my $done = AnyEvent->condvar;	648	my $done = AnyEvent->condvar;
…		…
585	they were a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
586	C<send>.	692	C<send>.
587		693
588	=item $cv->croak ($error)	694	=item $cv->croak ($error)
589		695
590	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
591	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
592		698
593	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
594	user/consumer. Doing it this way instead of calling C<croak> directly	700	user/consumer. Doing it this way instead of calling C<croak> directly
595	delays the error detetcion, but has the overwhelmign advantage that it	701	delays the error detection, but has the overwhelming advantage that it
596	diagnoses the error at the place where the result is expected, and not	702	diagnoses the error at the place where the result is expected, and not
597	deep in some event clalback without connection to the actual code causing	703	deep in some event callback with no connection to the actual code causing
598	the problem.	704	the problem.
599		705
600	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
601		707
602	=item $cv->end	708	=item $cv->end
…		…
605	one. For example, a function that pings many hosts in parallel might want	711	one. For example, a function that pings many hosts in parallel might want
606	to use a condition variable for the whole process.	712	to use a condition variable for the whole process.
607		713
608	Every call to C<< ->begin >> will increment a counter, and every call to	714	Every call to C<< ->begin >> will increment a counter, and every call to
609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
610	>>, the (last) callback passed to C<begin> will be executed. That callback	716	>>, the (last) callback passed to C<begin> will be executed, passing the
611	is I<supposed> to call C<< ->send >>, but that is not required. If no	717	condvar as first argument. That callback is I<supposed> to call C<< ->send
612	callback was set, C<send> will be called without any arguments.	718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
613		720
614	You can think of C<< $cv->send >> giving you an OR condition (one call	721	You can think of C<< $cv->send >> giving you an OR condition (one call
615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND	722	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).	723	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
617		724
…		…
639	one call to C<begin>, so the condvar waits for all calls to C<end> before	746	one call to C<begin>, so the condvar waits for all calls to C<end> before
640	sending.	747	sending.
641		748
642	The ping example mentioned above is slightly more complicated, as the	749	The ping example mentioned above is slightly more complicated, as the
643	there are results to be passwd back, and the number of tasks that are	750	there are results to be passwd back, and the number of tasks that are
644	begung can potentially be zero:	751	begun can potentially be zero:
645		752
646	my $cv = AnyEvent->condvar;	753	my $cv = AnyEvent->condvar;
647		754
648	my %result;	755	my %result;
649	$cv->begin (sub { $cv->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
650		757
651	for my $host (@list_of_hosts) {	758	for my $host (@list_of_hosts) {
652	$cv->begin;	759	$cv->begin;
653	ping_host_then_call_callback $host, sub {	760	ping_host_then_call_callback $host, sub {
654	$result{$host} = ...;	761	$result{$host} = ...;
…		…
670	to be called once the counter reaches C<0>, and second, it ensures that	777	to be called once the counter reaches C<0>, and second, it ensures that
671	C<send> is called even when C<no> hosts are being pinged (the loop	778	C<send> is called even when C<no> hosts are being pinged (the loop
672	doesn't execute once).	779	doesn't execute once).
673		780
674	This is the general pattern when you "fan out" into multiple (but	781	This is the general pattern when you "fan out" into multiple (but
675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set	782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
676	the callback and ensure C<end> is called at least once, and then, for each	783	the callback and ensure C<end> is called at least once, and then, for each
677	subrequest you start, call C<begin> and for each subrequest you finish,	784	subrequest you start, call C<begin> and for each subrequest you finish,
678	call C<end>.	785	call C<end>.
679		786
680	=back	787	=back
…		…
687	=over 4	794	=over 4
688		795
689	=item $cv->recv	796	=item $cv->recv
690		797
691	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
692	>> methods have been called on c<$cv>, while servicing other watchers	799	>> methods have been called on C<$cv>, while servicing other watchers
693	normally.	800	normally.
694		801
695	You can only wait once on a condition - additional calls are valid but	802	You can only wait once on a condition - additional calls are valid but
696	will return immediately.	803	will return immediately.
697		804
…		…
714	caller decide whether the call will block or not (for example, by coupling	821	caller decide whether the call will block or not (for example, by coupling
715	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
716	callbacks so the caller knows that getting the result will not block,	823	callbacks so the caller knows that getting the result will not block,
717	while still supporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
718		825
719	You can ensure that C<< -recv >> never blocks by setting a callback and	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
720	only calling C<< ->recv >> from within that callback (or at a later	827	only calling C<< ->recv >> from within that callback (or at a later
721	time). This will work even when the event loop does not support blocking	828	time). This will work even when the event loop does not support blocking
722	waits otherwise.	829	waits otherwise.
723		830
724	=item $bool = $cv->ready	831	=item $bool = $cv->ready
…		…
730		837
731	This is a mutator function that returns the callback set and optionally	838	This is a mutator function that returns the callback set and optionally
732	replaces it before doing so.	839	replaces it before doing so.
733		840
734	The callback will be called when the condition becomes "true", i.e. when	841	The callback will be called when the condition becomes "true", i.e. when
735	C<send> or C<croak> are called, with the only argument being the condition	842	C<send> or C<croak> are called, with the only argument being the
736	variable itself. Calling C<recv> inside the callback or at any later time	843	condition variable itself. If the condition is already true, the
737	is guaranteed not to block.	844	callback is called immediately when it is set. Calling C<recv> inside
		845	the callback or at any later time is guaranteed not to block.
738		846
739	=back	847	=back
740		848
741	=head1 SUPPORTED EVENT LOOPS/BACKENDS	849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
742		850
…		…
745	=over 4	853	=over 4
746		854
747	=item Backends that are autoprobed when no other event loop can be found.	855	=item Backends that are autoprobed when no other event loop can be found.
748		856
749	EV is the preferred backend when no other event loop seems to be in	857	EV is the preferred backend when no other event loop seems to be in
750	use. If EV is not installed, then AnyEvent will try Event, and, failing	858	use. If EV is not installed, then AnyEvent will fall back to its own
751	that, will fall back to its own pure-perl implementation, which is	859	pure-perl implementation, which is available everywhere as it comes with
752	available everywhere as it comes with AnyEvent itself.	860	AnyEvent itself.
753		861
754	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	862	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
755	AnyEvent::Impl::Event based on Event, very stable, few glitches.
756	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	863	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
757		864
758	=item Backends that are transparently being picked up when they are used.	865	=item Backends that are transparently being picked up when they are used.
759		866
760	These will be used when they are currently loaded when the first watcher	867	These will be used if they are already loaded when the first watcher
761	is created, in which case it is assumed that the application is using	868	is created, in which case it is assumed that the application is using
762	them. This means that AnyEvent will automatically pick the right backend	869	them. This means that AnyEvent will automatically pick the right backend
763	when the main program loads an event module before anything starts to	870	when the main program loads an event module before anything starts to
764	create watchers. Nothing special needs to be done by the main program.	871	create watchers. Nothing special needs to be done by the main program.
765		872
		873	AnyEvent::Impl::Event based on Event, very stable, few glitches.
766	AnyEvent::Impl::Glib based on Glib, slow but very stable.	874	AnyEvent::Impl::Glib based on Glib, slow but very stable.
767	AnyEvent::Impl::Tk based on Tk, very broken.	875	AnyEvent::Impl::Tk based on Tk, very broken.
768	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	876	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
769	AnyEvent::Impl::POE based on POE, very slow, some limitations.	877	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		878	AnyEvent::Impl::Irssi used when running within irssi.
770		879
771	=item Backends with special needs.	880	=item Backends with special needs.
772		881
773	Qt requires the Qt::Application to be instantiated first, but will	882	Qt requires the Qt::Application to be instantiated first, but will
774	otherwise be picked up automatically. As long as the main program	883	otherwise be picked up automatically. As long as the main program
…		…
779		888
780	Support for IO::Async can only be partial, as it is too broken and	889	Support for IO::Async can only be partial, as it is too broken and
781	architecturally limited to even support the AnyEvent API. It also	890	architecturally limited to even support the AnyEvent API. It also
782	is the only event loop that needs the loop to be set explicitly, so	891	is the only event loop that needs the loop to be set explicitly, so
783	it can only be used by a main program knowing about AnyEvent. See	892	it can only be used by a main program knowing about AnyEvent. See
784	L<AnyEvent::Impl::Async> for the gory details.	893	L<AnyEvent::Impl::IOAsync> for the gory details.
785		894
786	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.	895	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
787		896
788	=item Event loops that are indirectly supported via other backends.	897	=item Event loops that are indirectly supported via other backends.
789		898
…		…
817	Contains C<undef> until the first watcher is being created, before the	926	Contains C<undef> until the first watcher is being created, before the
818	backend has been autodetected.	927	backend has been autodetected.
819		928
820	Afterwards it contains the event model that is being used, which is the	929	Afterwards it contains the event model that is being used, which is the
821	name of the Perl class implementing the model. This class is usually one	930	name of the Perl class implementing the model. This class is usually one
822	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the	931	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
823	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it	932	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
824	will be C<urxvt::anyevent>).	933	will be C<urxvt::anyevent>).
825		934
826	=item AnyEvent::detect	935	=item AnyEvent::detect
827		936
828	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	937	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
829	if necessary. You should only call this function right before you would	938	if necessary. You should only call this function right before you would
830	have created an AnyEvent watcher anyway, that is, as late as possible at	939	have created an AnyEvent watcher anyway, that is, as late as possible at
831	runtime, and not e.g. while initialising of your module.	940	runtime, and not e.g. during initialisation of your module.
832		941
833	If you need to do some initialisation before AnyEvent watchers are	942	If you need to do some initialisation before AnyEvent watchers are
834	created, use C<post_detect>.	943	created, use C<post_detect>.
835		944
836	=item $guard = AnyEvent::post_detect { BLOCK }	945	=item $guard = AnyEvent::post_detect { BLOCK }
837		946
838	Arranges for the code block to be executed as soon as the event model is	947	Arranges for the code block to be executed as soon as the event model is
839	autodetected (or immediately if this has already happened).	948	autodetected (or immediately if that has already happened).
840		949
841	The block will be executed I<after> the actual backend has been detected	950	The block will be executed I<after> the actual backend has been detected
842	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been	951	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
843	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do	952	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
844	other initialisations - see the sources of L<AnyEvent::Strict> or	953	other initialisations - see the sources of L<AnyEvent::Strict> or
…		…
848	event module detection too early, for example, L<AnyEvent::AIO> creates	957	event module detection too early, for example, L<AnyEvent::AIO> creates
849	and installs the global L<IO::AIO> watcher in a C<post_detect> block to	958	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
850	avoid autodetecting the event module at load time.	959	avoid autodetecting the event module at load time.
851		960
852	If called in scalar or list context, then it creates and returns an object	961	If called in scalar or list context, then it creates and returns an object
853	that automatically removes the callback again when it is destroyed. See	962	that automatically removes the callback again when it is destroyed (or
		963	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
854	L<Coro::BDB> for a case where this is useful.	964	a case where this is useful.
		965
		966	Example: Create a watcher for the IO::AIO module and store it in
		967	C<$WATCHER>, but do so only do so after the event loop is initialised.
		968
		969	our WATCHER;
		970
		971	my $guard = AnyEvent::post_detect {
		972	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		973	};
		974
		975	# the ||= is important in case post_detect immediately runs the block,
		976	# as to not clobber the newly-created watcher. assigning both watcher and
		977	# post_detect guard to the same variable has the advantage of users being
		978	# able to just C<undef $WATCHER> if the watcher causes them grief.
		979
		980	$WATCHER ||= $guard;
855		981
856	=item @AnyEvent::post_detect	982	=item @AnyEvent::post_detect
857		983
858	If there are any code references in this array (you can C<push> to it	984	If there are any code references in this array (you can C<push> to it
859	before or after loading AnyEvent), then they will called directly after	985	before or after loading AnyEvent), then they will be called directly
860	the event loop has been chosen.	986	after the event loop has been chosen.
861		987
862	You should check C<$AnyEvent::MODEL> before adding to this array, though:	988	You should check C<$AnyEvent::MODEL> before adding to this array, though:
863	if it is defined then the event loop has already been detected, and the	989	if it is defined then the event loop has already been detected, and the
864	array will be ignored.	990	array will be ignored.
865		991
866	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows	992	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
867	it,as it takes care of these details.	993	it, as it takes care of these details.
868		994
869	This variable is mainly useful for modules that can do something useful	995	This variable is mainly useful for modules that can do something useful
870	when AnyEvent is used and thus want to know when it is initialised, but do	996	when AnyEvent is used and thus want to know when it is initialised, but do
871	not need to even load it by default. This array provides the means to hook	997	not need to even load it by default. This array provides the means to hook
872	into AnyEvent passively, without loading it.	998	into AnyEvent passively, without loading it.
873		999
		1000	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1001	together, you could put this into Coro (this is the actual code used by
		1002	Coro to accomplish this):
		1003
		1004	if (defined $AnyEvent::MODEL) {
		1005	# AnyEvent already initialised, so load Coro::AnyEvent
		1006	require Coro::AnyEvent;
		1007	} else {
		1008	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1009	# as soon as it is
		1010	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1011	}
		1012
874	=back	1013	=back
875		1014
876	=head1 WHAT TO DO IN A MODULE	1015	=head1 WHAT TO DO IN A MODULE
877		1016
878	As a module author, you should C<use AnyEvent> and call AnyEvent methods	1017	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
888	because it will stall the whole program, and the whole point of using	1027	because it will stall the whole program, and the whole point of using
889	events is to stay interactive.	1028	events is to stay interactive.
890		1029
891	It is fine, however, to call C<< ->recv >> when the user of your module	1030	It is fine, however, to call C<< ->recv >> when the user of your module
892	requests it (i.e. if you create a http request object ad have a method	1031	requests it (i.e. if you create a http request object ad have a method
893	called C<results> that returns the results, it should call C<< ->recv >>	1032	called C<results> that returns the results, it may call C<< ->recv >>
894	freely, as the user of your module knows what she is doing. always).	1033	freely, as the user of your module knows what she is doing. Always).
895		1034
896	=head1 WHAT TO DO IN THE MAIN PROGRAM	1035	=head1 WHAT TO DO IN THE MAIN PROGRAM
897		1036
898	There will always be a single main program - the only place that should	1037	There will always be a single main program - the only place that should
899	dictate which event model to use.	1038	dictate which event model to use.
900		1039
901	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1040	If the program is not event-based, it need not do anything special, even
902	do anything special (it does not need to be event-based) and let AnyEvent	1041	when it depends on a module that uses an AnyEvent. If the program itself
903	decide which implementation to chose if some module relies on it.	1042	uses AnyEvent, but does not care which event loop is used, all it needs
		1043	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1044	available loop implementation.
904		1045
905	If the main program relies on a specific event model - for example, in	1046	If the main program relies on a specific event model - for example, in
906	Gtk2 programs you have to rely on the Glib module - you should load the	1047	Gtk2 programs you have to rely on the Glib module - you should load the
907	event module before loading AnyEvent or any module that uses it: generally	1048	event module before loading AnyEvent or any module that uses it: generally
908	speaking, you should load it as early as possible. The reason is that	1049	speaking, you should load it as early as possible. The reason is that
909	modules might create watchers when they are loaded, and AnyEvent will	1050	modules might create watchers when they are loaded, and AnyEvent will
910	decide on the event model to use as soon as it creates watchers, and it	1051	decide on the event model to use as soon as it creates watchers, and it
911	might chose the wrong one unless you load the correct one yourself.	1052	might choose the wrong one unless you load the correct one yourself.
912		1053
913	You can chose to use a pure-perl implementation by loading the	1054	You can chose to use a pure-perl implementation by loading the
914	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1055	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
915	everywhere, but letting AnyEvent chose the model is generally better.	1056	everywhere, but letting AnyEvent chose the model is generally better.
916		1057
…		…
934	=head1 OTHER MODULES	1075	=head1 OTHER MODULES
935		1076
936	The following is a non-exhaustive list of additional modules that use	1077	The following is a non-exhaustive list of additional modules that use
937	AnyEvent as a client and can therefore be mixed easily with other AnyEvent	1078	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
938	modules and other event loops in the same program. Some of the modules	1079	modules and other event loops in the same program. Some of the modules
939	come with AnyEvent, most are available via CPAN.	1080	come as part of AnyEvent, the others are available via CPAN.
940		1081
941	=over 4	1082	=over 4
942		1083
943	=item L<AnyEvent::Util>	1084	=item L<AnyEvent::Util>
944		1085
945	Contains various utility functions that replace often-used but blocking	1086	Contains various utility functions that replace often-used blocking
946	functions such as C<inet_aton> by event-/callback-based versions.	1087	functions such as C<inet_aton> with event/callback-based versions.
947		1088
948	=item L<AnyEvent::Socket>	1089	=item L<AnyEvent::Socket>
949		1090
950	Provides various utility functions for (internet protocol) sockets,	1091	Provides various utility functions for (internet protocol) sockets,
951	addresses and name resolution. Also functions to create non-blocking tcp	1092	addresses and name resolution. Also functions to create non-blocking tcp
…		…
953		1094
954	=item L<AnyEvent::Handle>	1095	=item L<AnyEvent::Handle>
955		1096
956	Provide read and write buffers, manages watchers for reads and writes,	1097	Provide read and write buffers, manages watchers for reads and writes,
957	supports raw and formatted I/O, I/O queued and fully transparent and	1098	supports raw and formatted I/O, I/O queued and fully transparent and
958	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1099	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
959		1100
960	=item L<AnyEvent::DNS>	1101	=item L<AnyEvent::DNS>
961		1102
962	Provides rich asynchronous DNS resolver capabilities.	1103	Provides rich asynchronous DNS resolver capabilities.
963		1104
		1105	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1106
		1107	Implement event-based interfaces to the protocols of the same name (for
		1108	the curious, IGS is the International Go Server and FCP is the Freenet
		1109	Client Protocol).
		1110
		1111	=item L<AnyEvent::Handle::UDP>
		1112
		1113	Here be danger!
		1114
		1115	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1116	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1117	its use of a stream-based API with a protocol that isn't streamable, that
		1118	the only way to improve it is to delete it.
		1119
		1120	It features data corruption (but typically only under load) and general
		1121	confusion. On top, the author is not only clueless about UDP but also
		1122	fact-resistant - some gems of his understanding: "connect doesn't work
		1123	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1124	packets", "I don't need to implement proper error checking as UDP doesn't
		1125	support error checking" and so on - he doesn't even understand what's
		1126	wrong with his module when it is explained to him.
		1127
964	=item L<AnyEvent::HTTP>	1128	=item L<AnyEvent::DBI>
965		1129
966	A simple-to-use HTTP library that is capable of making a lot of concurrent	1130	Executes L<DBI> requests asynchronously in a proxy process for you,
967	HTTP requests.	1131	notifying you in an event-based way when the operation is finished.
		1132
		1133	=item L<AnyEvent::AIO>
		1134
		1135	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1136	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1137	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1138	file I/O, and much more.
968		1139
969	=item L<AnyEvent::HTTPD>	1140	=item L<AnyEvent::HTTPD>
970		1141
971	Provides a simple web application server framework.	1142	A simple embedded webserver.
972		1143
973	=item L<AnyEvent::FastPing>	1144	=item L<AnyEvent::FastPing>
974		1145
975	The fastest ping in the west.	1146	The fastest ping in the west.
976		1147
977	=item L<AnyEvent::DBI>
978
979	Executes L<DBI> requests asynchronously in a proxy process.
980
981	=item L<AnyEvent::AIO>
982
983	Truly asynchronous I/O, should be in the toolbox of every event
984	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
985	together.
986
987	=item L<AnyEvent::BDB>
988
989	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
990	L<BDB> and AnyEvent together.
991
992	=item L<AnyEvent::GPSD>
993
994	A non-blocking interface to gpsd, a daemon delivering GPS information.
995
996	=item L<AnyEvent::IRC>
997
998	AnyEvent based IRC client module family (replacing the older Net::IRC3).
999
1000	=item L<AnyEvent::XMPP>
1001
1002	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1003	Net::XMPP2>.
1004
1005	=item L<AnyEvent::IGS>
1006
1007	A non-blocking interface to the Internet Go Server protocol (used by
1008	L<App::IGS>).
1009
1010	=item L<Net::FCP>
1011
1012	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1013	of AnyEvent.
1014
1015	=item L<Event::ExecFlow>
1016
1017	High level API for event-based execution flow control.
1018
1019	=item L<Coro>	1148	=item L<Coro>
1020		1149
1021	Has special support for AnyEvent via L<Coro::AnyEvent>.	1150	Has special support for AnyEvent via L<Coro::AnyEvent>.
1022		1151
1023	=back	1152	=back
1024		1153
1025	=cut	1154	=cut
1026		1155
1027	package AnyEvent;	1156	package AnyEvent;
1028		1157
1029	no warnings;	1158	# basically a tuned-down version of common::sense
1030	use strict qw(vars subs);	1159	sub common_sense {
		1160	# from common:.sense 3.3
		1161	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf3\x0f\xc0\xf0\xfc\x33\x00";
		1162	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1163	$^H |= 0x00000600;
		1164	}
		1165
		1166	BEGIN { AnyEvent::common_sense }
1031		1167
1032	use Carp ();	1168	use Carp ();
1033		1169
1034	our $VERSION = 4.82;	1170	our $VERSION = '5.271';
1035	our $MODEL;	1171	our $MODEL;
1036		1172
1037	our $AUTOLOAD;	1173	our $AUTOLOAD;
1038	our @ISA;	1174	our @ISA;
1039		1175
1040	our @REGISTRY;	1176	our @REGISTRY;
1041		1177
1042	our $WIN32;	1178	our $VERBOSE;
1043		1179
1044	BEGIN {	1180	BEGIN {
1045	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";	1181	require "AnyEvent/constants.pl";
		1182
1046	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";	1183	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
1047		1184
1048	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}	1185	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
1049	if ${^TAINT};	1186	if ${^TAINT};
1050	}
1051		1187
1052	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1188	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1189
		1190	}
		1191
		1192	our $MAX_SIGNAL_LATENCY = 10;
1053		1193
1054	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1194	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
1055		1195
1056	{	1196	{
1057	my $idx;	1197	my $idx;
…		…
1059	for reverse split /\s*,\s*/,	1199	for reverse split /\s*,\s*/,
1060	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1200	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
1061	}	1201	}
1062		1202
1063	my @models = (	1203	my @models = (
1064	[EV:: => AnyEvent::Impl::EV::],	1204	[EV:: => AnyEvent::Impl::EV:: , 1],
1065	[Event:: => AnyEvent::Impl::Event::],
1066	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1205	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
1067	# everything below here will not be autoprobed	1206	# everything below here will not (normally) be autoprobed
1068	# as the pureperl backend should work everywhere	1207	# as the pureperl backend should work everywhere
1069	# and is usually faster	1208	# and is usually faster
		1209	[Event:: => AnyEvent::Impl::Event::, 1],
1070	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1210	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
1071	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1211	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1212	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
1072	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1213	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
1073	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1214	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
1074	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1215	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
1075	[Wx:: => AnyEvent::Impl::POE::],	1216	[Wx:: => AnyEvent::Impl::POE::],
1076	[Prima:: => AnyEvent::Impl::POE::],	1217	[Prima:: => AnyEvent::Impl::POE::],
1077	# IO::Async is just too broken - we would need workarounds for its	1218	# IO::Async is just too broken - we would need workarounds for its
1078	# byzantine signal and broken child handling, among others.	1219	# byzantine signal and broken child handling, among others.
1079	# IO::Async is rather hard to detect, as it doesn't have any	1220	# IO::Async is rather hard to detect, as it doesn't have any
1080	# obvious default class.	1221	# obvious default class.
1081	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program	1222	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
1082	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program	1223	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
1083	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program	1224	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1225	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
1084	);	1226	);
1085		1227
1086	our %method = map +($_ => 1),	1228	our %method = map +($_ => 1),
1087	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1229	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
1088		1230
1089	our @post_detect;	1231	our @post_detect;
1090		1232
1091	sub post_detect(&) {	1233	sub post_detect(&) {
1092	my ($cb) = @_;	1234	my ($cb) = @_;
1093		1235
1094	if ($MODEL) {
1095	$cb->();
1096
1097	1
1098	} else {
1099	push @post_detect, $cb;	1236	push @post_detect, $cb;
1100		1237
1101	defined wantarray	1238	defined wantarray
1102	? bless \$cb, "AnyEvent::Util::postdetect"	1239	? bless \$cb, "AnyEvent::Util::postdetect"
1103	: ()	1240	: ()
1104	}
1105	}	1241	}
1106		1242
1107	sub AnyEvent::Util::postdetect::DESTROY {	1243	sub AnyEvent::Util::postdetect::DESTROY {
1108	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1244	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1109	}	1245	}
1110		1246
1111	sub detect() {	1247	sub detect() {
		1248	# free some memory
		1249	*detect = sub () { $MODEL };
		1250
		1251	local $!; # for good measure
		1252	local $SIG{__DIE__};
		1253
		1254	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1255	my $model = "AnyEvent::Impl::$1";
		1256	if (eval "require $model") {
		1257	$MODEL = $model;
		1258	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1259	} else {
		1260	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1261	}
		1262	}
		1263
		1264	# check for already loaded models
1112	unless ($MODEL) {	1265	unless ($MODEL) {
1113	no strict 'refs';	1266	for (@REGISTRY, @models) {
1114	local $SIG{__DIE__};	1267	my ($package, $model) = @$_;
1115		1268	if (${"$package\::VERSION"} > 0) {
1116	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1117	my $model = "AnyEvent::Impl::$1";
1118	if (eval "require $model") {	1269	if (eval "require $model") {
1119	$MODEL = $model;	1270	$MODEL = $model;
1120	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1;	1271	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1121	} else {	1272	last;
1122	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose;	1273	}
1123	}	1274	}
1124	}	1275	}
1125		1276
1126	# check for already loaded models
1127	unless ($MODEL) {	1277	unless ($MODEL) {
		1278	# try to autoload a model
1128	for (@REGISTRY, @models) {	1279	for (@REGISTRY, @models) {
1129	my ($package, $model) = @$_;	1280	my ($package, $model, $autoload) = @$_;
		1281	if (
		1282	$autoload
		1283	and eval "require $package"
1130	if (${"$package\::VERSION"} > 0) {	1284	and ${"$package\::VERSION"} > 0
1131	if (eval "require $model") {	1285	and eval "require $model"
		1286	) {
1132	$MODEL = $model;	1287	$MODEL = $model;
1133	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1288	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1134	last;	1289	last;
1135	}
1136	}	1290	}
1137	}	1291	}
1138		1292
1139	unless ($MODEL) {
1140	# try to load a model
1141
1142	for (@REGISTRY, @models) {
1143	my ($package, $model) = @$_;
1144	if (eval "require $package"
1145	and ${"$package\::VERSION"} > 0
1146	and eval "require $model") {
1147	$MODEL = $model;
1148	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
1149	last;
1150	}
1151	}
1152
1153	$MODEL	1293	$MODEL
1154	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";	1294	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
1155	}
1156	}	1295	}
1157
1158	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
1159
1160	unshift @ISA, $MODEL;
1161
1162	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
1163
1164	(shift @post_detect)->() while @post_detect;
1165	}	1296	}
		1297
		1298	@models = (); # free probe data
		1299
		1300	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1301	unshift @ISA, $MODEL;
		1302
		1303	# now nuke some methods that are overriden by the backend.
		1304	# SUPER is not allowed.
		1305	for (qw(time signal child idle)) {
		1306	undef &{"AnyEvent::Base::$_"}
		1307	if defined &{"$MODEL\::$_"};
		1308	}
		1309
		1310	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1311
		1312	(shift @post_detect)->() while @post_detect;
		1313
		1314	*post_detect = sub(&) {
		1315	shift->();
		1316
		1317	undef
		1318	};
1166		1319
1167	$MODEL	1320	$MODEL
1168	}	1321	}
1169		1322
1170	sub AUTOLOAD {	1323	sub AUTOLOAD {
1171	(my $func = $AUTOLOAD) =~ s/.*://;	1324	(my $func = $AUTOLOAD) =~ s/.*://;
1172		1325
1173	$method{$func}	1326	$method{$func}
1174	or Carp::croak "$func: not a valid method for AnyEvent objects";	1327	or Carp::croak "$func: not a valid AnyEvent class method";
1175		1328
1176	detect unless $MODEL;	1329	detect;
1177		1330
1178	my $class = shift;	1331	my $class = shift;
1179	$class->$func (@_);	1332	$class->$func (@_);
1180	}	1333	}
1181		1334
…		…
1184	# allow only one watcher per fd, so we dup it to get a different one).	1337	# allow only one watcher per fd, so we dup it to get a different one).
1185	sub _dupfh($$;$$) {	1338	sub _dupfh($$;$$) {
1186	my ($poll, $fh, $r, $w) = @_;	1339	my ($poll, $fh, $r, $w) = @_;
1187		1340
1188	# cygwin requires the fh mode to be matching, unix doesn't	1341	# cygwin requires the fh mode to be matching, unix doesn't
1189	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");	1342	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1190		1343
1191	open my $fh2, "$mode&", $fh	1344	open my $fh2, $mode, $fh
1192	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";	1345	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1193		1346
1194	# we assume CLOEXEC is already set by perl in all important cases	1347	# we assume CLOEXEC is already set by perl in all important cases
1195		1348
1196	($fh2, $rw)	1349	($fh2, $rw)
1197	}	1350	}
1198		1351
		1352	=head1 SIMPLIFIED AE API
		1353
		1354	Starting with version 5.0, AnyEvent officially supports a second, much
		1355	simpler, API that is designed to reduce the calling, typing and memory
		1356	overhead by using function call syntax and a fixed number of parameters.
		1357
		1358	See the L<AE> manpage for details.
		1359
		1360	=cut
		1361
		1362	package AE;
		1363
		1364	our $VERSION = $AnyEvent::VERSION;
		1365
		1366	# fall back to the main API by default - backends and AnyEvent::Base
		1367	# implementations can overwrite these.
		1368
		1369	sub io($$$) {
		1370	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1371	}
		1372
		1373	sub timer($$$) {
		1374	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1375	}
		1376
		1377	sub signal($$) {
		1378	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1379	}
		1380
		1381	sub child($$) {
		1382	AnyEvent->child (pid => $_[0], cb => $_[1])
		1383	}
		1384
		1385	sub idle($) {
		1386	AnyEvent->idle (cb => $_[0])
		1387	}
		1388
		1389	sub cv(;&) {
		1390	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1391	}
		1392
		1393	sub now() {
		1394	AnyEvent->now
		1395	}
		1396
		1397	sub now_update() {
		1398	AnyEvent->now_update
		1399	}
		1400
		1401	sub time() {
		1402	AnyEvent->time
		1403	}
		1404
1199	package AnyEvent::Base;	1405	package AnyEvent::Base;
1200		1406
1201	# default implementations for many methods	1407	# default implementations for many methods
1202		1408
1203	BEGIN {	1409	sub time {
		1410	eval q{ # poor man's autoloading {}
		1411	# probe for availability of Time::HiRes
1204	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1412	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1413	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1205	*_time = \&Time::HiRes::time;	1414	*AE::time = \&Time::HiRes::time;
1206	# if (eval "use POSIX (); (POSIX::times())...	1415	# if (eval "use POSIX (); (POSIX::times())...
1207	} else {	1416	} else {
		1417	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1208	*_time = sub { time }; # epic fail	1418	*AE::time = sub (){ time }; # epic fail
		1419	}
		1420
		1421	*time = sub { AE::time }; # different prototypes
		1422	};
		1423	die if $@;
		1424
		1425	&time
		1426	}
		1427
		1428	*now = \&time;
		1429
		1430	sub now_update { }
		1431
		1432	# default implementation for ->condvar
		1433
		1434	sub condvar {
		1435	eval q{ # poor man's autoloading {}
		1436	*condvar = sub {
		1437	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1438	};
		1439
		1440	*AE::cv = sub (;&) {
		1441	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1442	};
		1443	};
		1444	die if $@;
		1445
		1446	&condvar
		1447	}
		1448
		1449	# default implementation for ->signal
		1450
		1451	our $HAVE_ASYNC_INTERRUPT;
		1452
		1453	sub _have_async_interrupt() {
		1454	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1455	&& eval "use Async::Interrupt 1.02 (); 1")
		1456	unless defined $HAVE_ASYNC_INTERRUPT;
		1457
		1458	$HAVE_ASYNC_INTERRUPT
		1459	}
		1460
		1461	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1462	our (%SIG_ASY, %SIG_ASY_W);
		1463	our ($SIG_COUNT, $SIG_TW);
		1464
		1465	# install a dummy wakeup watcher to reduce signal catching latency
		1466	# used by Impls
		1467	sub _sig_add() {
		1468	unless ($SIG_COUNT++) {
		1469	# try to align timer on a full-second boundary, if possible
		1470	my $NOW = AE::now;
		1471
		1472	$SIG_TW = AE::timer
		1473	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1474	$MAX_SIGNAL_LATENCY,
		1475	sub { } # just for the PERL_ASYNC_CHECK
		1476	;
1209	}	1477	}
1210	}	1478	}
1211		1479
1212	sub time { _time }	1480	sub _sig_del {
1213	sub now { _time }	1481	undef $SIG_TW
1214	sub now_update { }	1482	unless --$SIG_COUNT;
1215
1216	# default implementation for ->condvar
1217
1218	sub condvar {
1219	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1220	}	1483	}
1221		1484
1222	# default implementation for ->signal	1485	our $_sig_name_init; $_sig_name_init = sub {
		1486	eval q{ # poor man's autoloading {}
		1487	undef $_sig_name_init;
1223		1488
1224	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1489	if (_have_async_interrupt) {
		1490	*sig2num = \&Async::Interrupt::sig2num;
		1491	*sig2name = \&Async::Interrupt::sig2name;
		1492	} else {
		1493	require Config;
1225		1494
1226	sub _signal_exec {	1495	my %signame2num;
1227	sysread $SIGPIPE_R, my $dummy, 4;	1496	@signame2num{ split ' ', $Config::Config{sig_name} }
		1497	= split ' ', $Config::Config{sig_num};
1228		1498
1229	while (%SIG_EV) {	1499	my @signum2name;
1230	for (keys %SIG_EV) {	1500	@signum2name[values %signame2num] = keys %signame2num;
1231	delete $SIG_EV{$_};	1501
1232	$_->() for values %{ $SIG_CB{$_} || {} };	1502	*sig2num = sub($) {
		1503	$_[0] > 0 ? shift : $signame2num{+shift}
		1504	};
		1505	*sig2name = sub ($) {
		1506	$_[0] > 0 ? $signum2name[+shift] : shift
		1507	};
1233	}	1508	}
1234	}	1509	};
1235	}	1510	die if $@;
		1511	};
		1512
		1513	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1514	sub sig2name($) { &$_sig_name_init; &sig2name }
1236		1515
1237	sub signal {	1516	sub signal {
1238	my (undef, %arg) = @_;	1517	eval q{ # poor man's autoloading {}
		1518	# probe for availability of Async::Interrupt
		1519	if (_have_async_interrupt) {
		1520	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1239		1521
1240	unless ($SIGPIPE_R) {	1522	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1241	require Fcntl;	1523	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
1242		1524
1243	if (AnyEvent::WIN32) {
1244	require AnyEvent::Util;
1245
1246	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1247	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1248	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1249	} else {	1525	} else {
		1526	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1527
		1528	if (AnyEvent::WIN32) {
		1529	require AnyEvent::Util;
		1530
		1531	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1532	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1533	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1534	} else {
1250	pipe $SIGPIPE_R, $SIGPIPE_W;	1535	pipe $SIGPIPE_R, $SIGPIPE_W;
1251	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1536	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
1252	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1537	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
1253		1538
1254	# not strictly required, as $^F is normally 2, but let's make sure...	1539	# not strictly required, as $^F is normally 2, but let's make sure...
1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1540	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;	1541	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1542	}
		1543
		1544	$SIGPIPE_R
		1545	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1546
		1547	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
1257	}	1548	}
1258		1549
1259	$SIGPIPE_R	1550	*signal = $HAVE_ASYNC_INTERRUPT
1260	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1551	? sub {
		1552	my (undef, %arg) = @_;
1261		1553
1262	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1554	# async::interrupt
1263	}
1264
1265	my $signal = uc $arg{signal}	1555	my $signal = sig2num $arg{signal};
1266	or Carp::croak "required option 'signal' is missing";
1267
1268	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1556	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1557
		1558	$SIG_ASY{$signal} ||= new Async::Interrupt
		1559	cb => sub { undef $SIG_EV{$signal} },
		1560	signal => $signal,
		1561	pipe => [$SIGPIPE_R->filenos],
		1562	pipe_autodrain => 0,
		1563	;
		1564
		1565	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1566	}
		1567	: sub {
		1568	my (undef, %arg) = @_;
		1569
		1570	# pure perl
		1571	my $signal = sig2name $arg{signal};
		1572	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1573
1269	$SIG{$signal} ||= sub {	1574	$SIG{$signal} ||= sub {
1270	local $!;	1575	local $!;
1271	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1576	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1272	undef $SIG_EV{$signal};	1577	undef $SIG_EV{$signal};
		1578	};
		1579
		1580	# can't do signal processing without introducing races in pure perl,
		1581	# so limit the signal latency.
		1582	_sig_add;
		1583
		1584	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1585	}
		1586	;
		1587
		1588	*AnyEvent::Base::signal::DESTROY = sub {
		1589	my ($signal, $cb) = @{$_[0]};
		1590
		1591	_sig_del;
		1592
		1593	delete $SIG_CB{$signal}{$cb};
		1594
		1595	$HAVE_ASYNC_INTERRUPT
		1596	? delete $SIG_ASY{$signal}
		1597	: # delete doesn't work with older perls - they then
		1598	# print weird messages, or just unconditionally exit
		1599	# instead of getting the default action.
		1600	undef $SIG{$signal}
		1601	unless keys %{ $SIG_CB{$signal} };
		1602	};
		1603
		1604	*_signal_exec = sub {
		1605	$HAVE_ASYNC_INTERRUPT
		1606	? $SIGPIPE_R->drain
		1607	: sysread $SIGPIPE_R, (my $dummy), 9;
		1608
		1609	while (%SIG_EV) {
		1610	for (keys %SIG_EV) {
		1611	delete $SIG_EV{$_};
		1612	$_->() for values %{ $SIG_CB{$_} || {} };
		1613	}
		1614	}
		1615	};
1273	};	1616	};
		1617	die if $@;
1274		1618
1275	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1619	&signal
1276	}
1277
1278	sub AnyEvent::Base::signal::DESTROY {
1279	my ($signal, $cb) = @{$_[0]};
1280
1281	delete $SIG_CB{$signal}{$cb};
1282
1283	# delete doesn't work with older perls - they then
1284	# print weird messages, or just unconditionally exit
1285	# instead of getting the default action.
1286	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1287	}	1620	}
1288		1621
1289	# default implementation for ->child	1622	# default implementation for ->child
1290		1623
1291	our %PID_CB;	1624	our %PID_CB;
1292	our $CHLD_W;	1625	our $CHLD_W;
1293	our $CHLD_DELAY_W;	1626	our $CHLD_DELAY_W;
1294	our $WNOHANG;	1627	our $WNOHANG;
1295		1628
1296	sub _sigchld {	1629	# used by many Impl's
1297	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1630	sub _emit_childstatus($$) {
		1631	my (undef, $rpid, $rstatus) = @_;
		1632
		1633	$_->($rpid, $rstatus)
1298	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1634	for values %{ $PID_CB{$rpid} || {} },
1299	(values %{ $PID_CB{0} || {} });	1635	values %{ $PID_CB{0} || {} };
1300	}
1301	}	1636	}
1302		1637
1303	sub child {	1638	sub child {
		1639	eval q{ # poor man's autoloading {}
		1640	*_sigchld = sub {
		1641	my $pid;
		1642
		1643	AnyEvent->_emit_childstatus ($pid, $?)
		1644	while ($pid = waitpid -1, $WNOHANG) > 0;
		1645	};
		1646
		1647	*child = sub {
1304	my (undef, %arg) = @_;	1648	my (undef, %arg) = @_;
1305		1649
1306	defined (my $pid = $arg{pid} + 0)	1650	defined (my $pid = $arg{pid} + 0)
1307	or Carp::croak "required option 'pid' is missing";	1651	or Carp::croak "required option 'pid' is missing";
1308		1652
1309	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1653	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1310		1654
		1655	# WNOHANG is almost cetrainly 1 everywhere
		1656	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1657	? 1
1311	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1658	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1312		1659
1313	unless ($CHLD_W) {	1660	unless ($CHLD_W) {
1314	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1661	$CHLD_W = AE::signal CHLD => \&_sigchld;
1315	# child could be a zombie already, so make at least one round	1662	# child could be a zombie already, so make at least one round
1316	&_sigchld;	1663	&_sigchld;
1317	}	1664	}
1318		1665
1319	bless [$pid, $arg{cb}], "AnyEvent::Base::child"	1666	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1320	}	1667	};
1321		1668
1322	sub AnyEvent::Base::child::DESTROY {	1669	*AnyEvent::Base::child::DESTROY = sub {
1323	my ($pid, $cb) = @{$_[0]};	1670	my ($pid, $cb) = @{$_[0]};
1324		1671
1325	delete $PID_CB{$pid}{$cb};	1672	delete $PID_CB{$pid}{$cb};
1326	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1673	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1327		1674
1328	undef $CHLD_W unless keys %PID_CB;	1675	undef $CHLD_W unless keys %PID_CB;
		1676	};
		1677	};
		1678	die if $@;
		1679
		1680	&child
1329	}	1681	}
1330		1682
1331	# idle emulation is done by simply using a timer, regardless	1683	# idle emulation is done by simply using a timer, regardless
1332	# of whether the process is idle or not, and not letting	1684	# of whether the process is idle or not, and not letting
1333	# the callback use more than 50% of the time.	1685	# the callback use more than 50% of the time.
1334	sub idle {	1686	sub idle {
		1687	eval q{ # poor man's autoloading {}
		1688	*idle = sub {
1335	my (undef, %arg) = @_;	1689	my (undef, %arg) = @_;
1336		1690
1337	my ($cb, $w, $rcb) = $arg{cb};	1691	my ($cb, $w, $rcb) = $arg{cb};
1338		1692
1339	$rcb = sub {	1693	$rcb = sub {
1340	if ($cb) {	1694	if ($cb) {
1341	$w = _time;	1695	$w = _time;
1342	&$cb;	1696	&$cb;
1343	$w = _time - $w;	1697	$w = _time - $w;
1344		1698
1345	# never use more then 50% of the time for the idle watcher,	1699	# never use more then 50% of the time for the idle watcher,
1346	# within some limits	1700	# within some limits
1347	$w = 0.0001 if $w < 0.0001;	1701	$w = 0.0001 if $w < 0.0001;
1348	$w = 5 if $w > 5;	1702	$w = 5 if $w > 5;
1349		1703
1350	$w = AnyEvent->timer (after => $w, cb => $rcb);	1704	$w = AE::timer $w, 0, $rcb;
1351	} else {	1705	} else {
1352	# clean up...	1706	# clean up...
1353	undef $w;	1707	undef $w;
1354	undef $rcb;	1708	undef $rcb;
		1709	}
		1710	};
		1711
		1712	$w = AE::timer 0.05, 0, $rcb;
		1713
		1714	bless \\$cb, "AnyEvent::Base::idle"
1355	}	1715	};
		1716
		1717	*AnyEvent::Base::idle::DESTROY = sub {
		1718	undef $${$_[0]};
		1719	};
1356	};	1720	};
		1721	die if $@;
1357		1722
1358	$w = AnyEvent->timer (after => 0.05, cb => $rcb);	1723	&idle
1359
1360	bless \\$cb, "AnyEvent::Base::idle"
1361	}
1362
1363	sub AnyEvent::Base::idle::DESTROY {
1364	undef $${$_[0]};
1365	}	1724	}
1366		1725
1367	package AnyEvent::CondVar;	1726	package AnyEvent::CondVar;
1368		1727
1369	our @ISA = AnyEvent::CondVar::Base::;	1728	our @ISA = AnyEvent::CondVar::Base::;
1370		1729
1371	package AnyEvent::CondVar::Base;	1730	package AnyEvent::CondVar::Base;
1372		1731
1373	use overload	1732	#use overload
1374	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1733	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1375	fallback => 1;	1734	# fallback => 1;
		1735
		1736	# save 300+ kilobytes by dirtily hardcoding overloading
		1737	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1738	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1739	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1740	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
1376		1741
1377	our $WAITING;	1742	our $WAITING;
1378		1743
1379	sub _send {	1744	sub _send {
1380	# nop	1745	# nop
…		…
1411	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1776	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1412	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1777	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1413	}	1778	}
1414		1779
1415	sub cb {	1780	sub cb {
1416	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1781	my $cv = shift;
		1782
		1783	@_
		1784	and $cv->{_ae_cb} = shift
		1785	and $cv->{_ae_sent}
		1786	and (delete $cv->{_ae_cb})->($cv);
		1787
1417	$_[0]{_ae_cb}	1788	$cv->{_ae_cb}
1418	}	1789	}
1419		1790
1420	sub begin {	1791	sub begin {
1421	++$_[0]{_ae_counter};	1792	++$_[0]{_ae_counter};
1422	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1793	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1471	C<PERL_ANYEVENT_MODEL>.	1842	C<PERL_ANYEVENT_MODEL>.
1472		1843
1473	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1844	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1474	model it chooses.	1845	model it chooses.
1475		1846
		1847	When set to C<8> or higher, then AnyEvent will report extra information on
		1848	which optional modules it loads and how it implements certain features.
		1849
1476	=item C<PERL_ANYEVENT_STRICT>	1850	=item C<PERL_ANYEVENT_STRICT>
1477		1851
1478	AnyEvent does not do much argument checking by default, as thorough	1852	AnyEvent does not do much argument checking by default, as thorough
1479	argument checking is very costly. Setting this variable to a true value	1853	argument checking is very costly. Setting this variable to a true value
1480	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1854	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1481	check the arguments passed to most method calls. If it finds any problems,	1855	check the arguments passed to most method calls. If it finds any problems,
1482	it will croak.	1856	it will croak.
1483		1857
1484	In other words, enables "strict" mode.	1858	In other words, enables "strict" mode.
1485		1859
1486	Unlike C<use strict>, it is definitely recommended to keep it off in	1860	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1487	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1861	>>, it is definitely recommended to keep it off in production. Keeping
1488	developing programs can be very useful, however.	1862	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1863	can be very useful, however.
1489		1864
1490	=item C<PERL_ANYEVENT_MODEL>	1865	=item C<PERL_ANYEVENT_MODEL>
1491		1866
1492	This can be used to specify the event model to be used by AnyEvent, before	1867	This can be used to specify the event model to be used by AnyEvent, before
1493	auto detection and -probing kicks in. It must be a string consisting	1868	auto detection and -probing kicks in. It must be a string consisting
…		…
1555		1930
1556	When neither C<ca_file> nor C<ca_path> was specified during	1931	When neither C<ca_file> nor C<ca_path> was specified during
1557	L<AnyEvent::TLS> context creation, and either of these environment	1932	L<AnyEvent::TLS> context creation, and either of these environment
1558	variables exist, they will be used to specify CA certificate locations	1933	variables exist, they will be used to specify CA certificate locations
1559	instead of a system-dependent default.	1934	instead of a system-dependent default.
		1935
		1936	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1937
		1938	When these are set to C<1>, then the respective modules are not
		1939	loaded. Mostly good for testing AnyEvent itself.
1560		1940
1561	=back	1941	=back
1562		1942
1563	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1943	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1564		1944
…		…
1622	warn "read: $input\n"; # output what has been read	2002	warn "read: $input\n"; # output what has been read
1623	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2003	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1624	},	2004	},
1625	);	2005	);
1626		2006
1627	my $time_watcher; # can only be used once
1628
1629	sub new_timer {
1630	$timer = AnyEvent->timer (after => 1, cb => sub {	2007	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1631	warn "timeout\n"; # print 'timeout' about every second	2008	warn "timeout\n"; # print 'timeout' at most every second
1632	&new_timer; # and restart the time
1633	});	2009	});
1634	}
1635
1636	new_timer; # create first timer
1637		2010
1638	$cv->recv; # wait until user enters /^q/i	2011	$cv->recv; # wait until user enters /^q/i
1639		2012
1640	=head1 REAL-WORLD EXAMPLE	2013	=head1 REAL-WORLD EXAMPLE
1641		2014
…		…
1714		2087
1715	The actual code goes further and collects all errors (C<die>s, exceptions)	2088	The actual code goes further and collects all errors (C<die>s, exceptions)
1716	that occurred during request processing. The C<result> method detects	2089	that occurred during request processing. The C<result> method detects
1717	whether an exception as thrown (it is stored inside the $txn object)	2090	whether an exception as thrown (it is stored inside the $txn object)
1718	and just throws the exception, which means connection errors and other	2091	and just throws the exception, which means connection errors and other
1719	problems get reported tot he code that tries to use the result, not in a	2092	problems get reported to the code that tries to use the result, not in a
1720	random callback.	2093	random callback.
1721		2094
1722	All of this enables the following usage styles:	2095	All of this enables the following usage styles:
1723		2096
1724	1. Blocking:	2097	1. Blocking:
…		…
1772	through AnyEvent. The benchmark creates a lot of timers (with a zero	2145	through AnyEvent. The benchmark creates a lot of timers (with a zero
1773	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2146	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1774	which it is), lets them fire exactly once and destroys them again.	2147	which it is), lets them fire exactly once and destroys them again.
1775		2148
1776	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2149	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1777	distribution.	2150	distribution. It uses the L<AE> interface, which makes a real difference
		2151	for the EV and Perl backends only.
1778		2152
1779	=head3 Explanation of the columns	2153	=head3 Explanation of the columns
1780		2154
1781	I<watcher> is the number of event watchers created/destroyed. Since	2155	I<watcher> is the number of event watchers created/destroyed. Since
1782	different event models feature vastly different performances, each event	2156	different event models feature vastly different performances, each event
…		…
1803	watcher.	2177	watcher.
1804		2178
1805	=head3 Results	2179	=head3 Results
1806		2180
1807	name watchers bytes create invoke destroy comment	2181	name watchers bytes create invoke destroy comment
1808	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2182	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1809	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2183	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1810	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2184	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1811	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2185	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1812	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2186	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1813	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2187	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1814	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	2188	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1815	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	2189	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1816	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2190	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1817	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2191	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1818	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2192	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1819	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2193	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1820		2194
1821	=head3 Discussion	2195	=head3 Discussion
1822		2196
1823	The benchmark does I<not> measure scalability of the event loop very	2197	The benchmark does I<not> measure scalability of the event loop very
1824	well. For example, a select-based event loop (such as the pure perl one)	2198	well. For example, a select-based event loop (such as the pure perl one)
…		…
1836	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2210	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1837	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2211	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1838	cycles with POE.	2212	cycles with POE.
1839		2213
1840	C<EV> is the sole leader regarding speed and memory use, which are both	2214	C<EV> is the sole leader regarding speed and memory use, which are both
1841	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2215	maximal/minimal, respectively. When using the L<AE> API there is zero
		2216	overhead (when going through the AnyEvent API create is about 5-6 times
		2217	slower, with other times being equal, so still uses far less memory than
1842	far less memory than any other event loop and is still faster than Event	2218	any other event loop and is still faster than Event natively).
1843	natively.
1844		2219
1845	The pure perl implementation is hit in a few sweet spots (both the	2220	The pure perl implementation is hit in a few sweet spots (both the
1846	constant timeout and the use of a single fd hit optimisations in the perl	2221	constant timeout and the use of a single fd hit optimisations in the perl
1847	interpreter and the backend itself). Nevertheless this shows that it	2222	interpreter and the backend itself). Nevertheless this shows that it
1848	adds very little overhead in itself. Like any select-based backend its	2223	adds very little overhead in itself. Like any select-based backend its
…		…
1922	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2297	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1923	(1%) are active. This mirrors the activity of large servers with many	2298	(1%) are active. This mirrors the activity of large servers with many
1924	connections, most of which are idle at any one point in time.	2299	connections, most of which are idle at any one point in time.
1925		2300
1926	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2301	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1927	distribution.	2302	distribution. It uses the L<AE> interface, which makes a real difference
		2303	for the EV and Perl backends only.
1928		2304
1929	=head3 Explanation of the columns	2305	=head3 Explanation of the columns
1930		2306
1931	I<sockets> is the number of sockets, and twice the number of "servers" (as	2307	I<sockets> is the number of sockets, and twice the number of "servers" (as
1932	each server has a read and write socket end).	2308	each server has a read and write socket end).
…		…
1940	a new one that moves the timeout into the future.	2316	a new one that moves the timeout into the future.
1941		2317
1942	=head3 Results	2318	=head3 Results
1943		2319
1944	name sockets create request	2320	name sockets create request
1945	EV 20000 69.01 11.16	2321	EV 20000 62.66 7.99
1946	Perl 20000 73.32 35.87	2322	Perl 20000 68.32 32.64
1947	IOAsync 20000 157.00 98.14 epoll	2323	IOAsync 20000 174.06 101.15 epoll
1948	IOAsync 20000 159.31 616.06 poll	2324	IOAsync 20000 174.67 610.84 poll
1949	Event 20000 212.62 257.32	2325	Event 20000 202.69 242.91
1950	Glib 20000 651.16 1896.30	2326	Glib 20000 557.01 1689.52
1951	POE 20000 349.67 12317.24 uses POE::Loop::Event	2327	POE 20000 341.54 12086.32 uses POE::Loop::Event
1952		2328
1953	=head3 Discussion	2329	=head3 Discussion
1954		2330
1955	This benchmark I<does> measure scalability and overall performance of the	2331	This benchmark I<does> measure scalability and overall performance of the
1956	particular event loop.	2332	particular event loop.
…		…
2082	As you can see, the AnyEvent + EV combination even beats the	2458	As you can see, the AnyEvent + EV combination even beats the
2083	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	2459	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
2084	backend easily beats IO::Lambda and POE.	2460	backend easily beats IO::Lambda and POE.
2085		2461
2086	And even the 100% non-blocking version written using the high-level (and	2462	And even the 100% non-blocking version written using the high-level (and
2087	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a	2463	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
2088	large margin, even though it does all of DNS, tcp-connect and socket I/O	2464	higher level ("unoptimised") abstractions by a large margin, even though
2089	in a non-blocking way.	2465	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
2090		2466
2091	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and	2467	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
2092	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are	2468	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
2093	part of the IO::lambda distribution and were used without any changes.	2469	part of the IO::Lambda distribution and were used without any changes.
2094		2470
2095		2471
2096	=head1 SIGNALS	2472	=head1 SIGNALS
2097		2473
2098	AnyEvent currently installs handlers for these signals:	2474	AnyEvent currently installs handlers for these signals:
…		…
2132	if $SIG{CHLD} eq 'IGNORE';	2508	if $SIG{CHLD} eq 'IGNORE';
2133		2509
2134	$SIG{PIPE} = sub { }	2510	$SIG{PIPE} = sub { }
2135	unless defined $SIG{PIPE};	2511	unless defined $SIG{PIPE};
2136		2512
		2513	=head1 RECOMMENDED/OPTIONAL MODULES
		2514
		2515	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2516	its built-in modules) are required to use it.
		2517
		2518	That does not mean that AnyEvent won't take advantage of some additional
		2519	modules if they are installed.
		2520
		2521	This section explains which additional modules will be used, and how they
		2522	affect AnyEvent's operation.
		2523
		2524	=over 4
		2525
		2526	=item L<Async::Interrupt>
		2527
		2528	This slightly arcane module is used to implement fast signal handling: To
		2529	my knowledge, there is no way to do completely race-free and quick
		2530	signal handling in pure perl. To ensure that signals still get
		2531	delivered, AnyEvent will start an interval timer to wake up perl (and
		2532	catch the signals) with some delay (default is 10 seconds, look for
		2533	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2534
		2535	If this module is available, then it will be used to implement signal
		2536	catching, which means that signals will not be delayed, and the event loop
		2537	will not be interrupted regularly, which is more efficient (and good for
		2538	battery life on laptops).
		2539
		2540	This affects not just the pure-perl event loop, but also other event loops
		2541	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2542
		2543	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2544	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2545	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2546	does nothing for those backends.
		2547
		2548	=item L<EV>
		2549
		2550	This module isn't really "optional", as it is simply one of the backend
		2551	event loops that AnyEvent can use. However, it is simply the best event
		2552	loop available in terms of features, speed and stability: It supports
		2553	the AnyEvent API optimally, implements all the watcher types in XS, does
		2554	automatic timer adjustments even when no monotonic clock is available,
		2555	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2556	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2557	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2558
		2559	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2560	then this module will do nothing for you.
		2561
		2562	=item L<Guard>
		2563
		2564	The guard module, when used, will be used to implement
		2565	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2566	lot less memory), but otherwise doesn't affect guard operation much. It is
		2567	purely used for performance.
		2568
		2569	=item L<JSON> and L<JSON::XS>
		2570
		2571	One of these modules is required when you want to read or write JSON data
		2572	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2573	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2574
		2575	=item L<Net::SSLeay>
		2576
		2577	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2578	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2579	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2580
		2581	=item L<Time::HiRes>
		2582
		2583	This module is part of perl since release 5.008. It will be used when the
		2584	chosen event library does not come with a timing source of its own. The
		2585	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2586	try to use a monotonic clock for timing stability.
		2587
		2588	=back
		2589
		2590
2137	=head1 FORK	2591	=head1 FORK
2138		2592
2139	Most event libraries are not fork-safe. The ones who are usually are	2593	Most event libraries are not fork-safe. The ones who are usually are
2140	because they rely on inefficient but fork-safe C<select> or C<poll>	2594	because they rely on inefficient but fork-safe C<select> or C<poll> calls
2141	calls. Only L<EV> is fully fork-aware.	2595	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2596	are usually badly thought-out hacks that are incompatible with fork in
		2597	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2598	continue event-processing in both parent and child (or both, if you know
		2599	what you are doing).
		2600
		2601	This means that, in general, you cannot fork and do event processing in
		2602	the child if the event library was initialised before the fork (which
		2603	usually happens when the first AnyEvent watcher is created, or the library
		2604	is loaded).
2142		2605
2143	If you have to fork, you must either do so I<before> creating your first	2606	If you have to fork, you must either do so I<before> creating your first
2144	watcher OR you must not use AnyEvent at all in the child.	2607	watcher OR you must not use AnyEvent at all in the child OR you must do
		2608	something completely out of the scope of AnyEvent.
		2609
		2610	The problem of doing event processing in the parent I<and> the child
		2611	is much more complicated: even for backends that I<are> fork-aware or
		2612	fork-safe, their behaviour is not usually what you want: fork clones all
		2613	watchers, that means all timers, I/O watchers etc. are active in both
		2614	parent and child, which is almost never what you want. USing C<exec>
		2615	to start worker children from some kind of manage rprocess is usually
		2616	preferred, because it is much easier and cleaner, at the expense of having
		2617	to have another binary.
2145		2618
2146		2619
2147	=head1 SECURITY CONSIDERATIONS	2620	=head1 SECURITY CONSIDERATIONS
2148		2621
2149	AnyEvent can be forced to load any event model via	2622	AnyEvent can be forced to load any event model via
…		…
2187	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2660	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
2188		2661
2189	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2662	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
2190	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2663	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
2191	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2664	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
2192	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.	2665	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
2193		2666
2194	Non-blocking file handles, sockets, TCP clients and	2667	Non-blocking file handles, sockets, TCP clients and
2195	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.	2668	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
2196		2669
2197	Asynchronous DNS: L<AnyEvent::DNS>.	2670	Asynchronous DNS: L<AnyEvent::DNS>.

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