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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, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
22		42
23	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
24		44
25	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
26	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
27	L<AnyEvent::Intro> manpage.	47	L<AnyEvent::Intro> manpage.
28		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
		58
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		60
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
33		63
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
36		66
37	First and foremost, I<AnyEvent is not an event model> itself, it only	67	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	68	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	69	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	70	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	71	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
43		74
44	The goal of AnyEvent is to offer module authors the ability to do event	75	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	76	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	77	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
48	model you use.	79	model you use.
49		80
50	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	84	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	85	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
56		87
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
60	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
61	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
62	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
63	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
64	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
65		96
66	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
70	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
71	technically possible.	102	technically possible.
72		103
73	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
74	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
80	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
81	model, you should I<not> use this module.	112	model, you should I<not> use this module.
82		113
83	=head1 DESCRIPTION	114	=head1 DESCRIPTION
84		115
85	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
86	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
87	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
88	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
89		120
90	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
91	module.	122	module.
92		123
93	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
94	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
95	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
96	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
97	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
98	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
99	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Loop> should always work, so
100	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
101	found, AnyEvent will fall back to a pure-perl event loop, which is not
102	very efficient, but should work everywhere.
103		132
104	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
105	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
106	that model the default. For example:	135	that model the default. For example:
107		136
…		…
109	use AnyEvent;	138	use AnyEvent;
110		139
111	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
112		141
113	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
114	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
115	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
116		146
117	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
118	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	other event modules you can load it explicitly and enjoy the high
119	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
120		150
121	=head1 WATCHERS	151	=head1 WATCHERS
122		152
123	AnyEvent has the central concept of a I<watcher>, which is an object that	153	AnyEvent has the central concept of a I<watcher>, which is an object that
124	stores relevant data for each kind of event you are waiting for, such as	154	stores relevant data for each kind of event you are waiting for, such as
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
129	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
130	is in control).	160	is in control).
131		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
132	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
133	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	170	to it).
135		171
136	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
137		173
138	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
139	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
140		176
141	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
142		178
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
145	undef $w;	181	undef $w;
146	});	182	});
…		…
149	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
150	declared.	186	declared.
151		187
152	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
153		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
156		198
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
158	(AnyEvent might or might not keep a reference to this file handle). C<poll>	200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
159	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
160	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
161	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
162		210
163	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
166		214
167	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
168	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
169	underlying file descriptor.	217	underlying file descriptor.
170		218
171	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
173	handles.	221	handles.
174		222
175	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
176	watcher.	224	watcher.
…		…
181	undef $w;	229	undef $w;
182	});	230	});
183		231
184	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
185		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	243	method with the following mandatory arguments:
188		244
189	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		248
193	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
196		252
197	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
198	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
199	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
200	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
201	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
202		258
203	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
204	attempt is done to avoid timer drift in most backends, so the interval is	260	attempt is made to avoid timer drift in most backends, so the interval is
205	only approximate.	261	only approximate.
206		262
207	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
208		264
209	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
227		283
228	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
229	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
230	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
231	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
232	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
233		289
234	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
235	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
236	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
237	timers.	293	timers.
238		294
239	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
240	AnyEvent API.	296	AnyEvent API.
…		…
262	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
263	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
264		320
265	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
266	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
267	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
268		324
269	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
270	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
271		327
272	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
273	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
274		330
275	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
276	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
277	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
278	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
279	after three seconds.	335	after three seconds.
280		336
…		…
298	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
299	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
300	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
301	account.	357	account.
302		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
		362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
		363	above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
303	=back	381	=back
304		382
305	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
306		386
307	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
308	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
309	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
310		390
…		…
316	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
317	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
318	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
319		399
320	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
321	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
322		403
323	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
324	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
325		407
326	Example: exit on SIGINT	408	Example: exit on SIGINT
327		409
328	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
329		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
330	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
331		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
332	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
333		454
334	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
335	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
336	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
337	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
338	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
339	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
340		469
341	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
342	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
343	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
344		473
345	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
346	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
347	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
348		480
349	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
350	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
351	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which case the latency and race
		488	problems mentioned in the description of signal watchers apply.
352		489
353	Example: fork a process and wait for it	490	Example: fork a process and wait for it
354		491
355	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
356		493
…		…
366	);	503	);
367		504
368	# do something else, then wait for process exit	505	# do something else, then wait for process exit
369	$done->recv;	506	$done->recv;
370		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
		547
371	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
372		554
373	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
374	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
375	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
376		558
377	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
378	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
379		561
380	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
381	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
382		566
383	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
384	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
385	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
386	becomes true.	570	becomes true, with the condition variable as the first argument (but not
		571	the results).
387		572
388	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
389	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
390	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
391	->send >> method).	576	->send >> method).
392		577
393	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
394	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
395	in time where multiple outstanding events have been processed. And yet	580
396	another way to call them is transactions - each condition variable can be	581	=over 4
397	used to represent a transaction, which finishes at some point and delivers	582
398	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
399		601
400	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
401	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
402	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
403	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
416		618
417	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
418	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
419	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
420	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
421	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
422		624
423	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
424	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
425	for the send to occur.	627	for the send to occur.
426		628
427	Example: wait for a timer.	629	Example: wait for a timer.
428		630
429	# wait till the result is ready	631	# condition: "wait till the timer is fired"
430	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
431		633
432	# do something such as adding a timer	634	# create the timer - we could wait for, say
433	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
434	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
435	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
436	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
437	after => 1,	639	after => 1,
438	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
439	);	641	);
440		642
441	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
442	# calls send	644	# calls ->send
443	$result_ready->recv;	645	$timer_fired->recv;
444		646
445	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
446	condition variables are also code references.	648	variables are also callable directly.
447		649
448	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
449	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
450	$done->recv;	652	$done->recv;
		653
		654	Example: Imagine an API that returns a condvar and doesn't support
		655	callbacks. This is how you make a synchronous call, for example from
		656	the main program:
		657
		658	use AnyEvent::CouchDB;
		659
		660	...
		661
		662	my @info = $couchdb->info->recv;
		663
		664	And this is how you would just set a callback to be called whenever the
		665	results are available:
		666
		667	$couchdb->info->cb (sub {
		668	my @info = $_[0]->recv;
		669	});
451		670
452	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
453		672
454	These methods should only be used by the producing side, i.e. the	673	These methods should only be used by the producing side, i.e. the
455	code/module that eventually sends the signal. Note that it is also	674	code/module that eventually sends the signal. Note that it is also
…		…
468	immediately from within send.	687	immediately from within send.
469		688
470	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
471	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
472		691
473	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
474	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
475	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
476	overloading, so as tempting as it may be, passing a condition variable
477	instead of a callback does not work. Both the pure perl and EV loops
478	support overloading, however, as well as all functions that use perl to
479	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
480	example).
481		695
482	=item $cv->croak ($error)	696	=item $cv->croak ($error)
483		697
484	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
485	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
486		700
487	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
488	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
489		707
490	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
491		709
492	=item $cv->end	710	=item $cv->end
493
494	These two methods are EXPERIMENTAL and MIGHT CHANGE.
495		711
496	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
497	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
498	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
499		715
500	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
501	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
502	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
503	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
504	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
505		722
506	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
507		730
508	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
509		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
510	my %result;	757	my %result;
511	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
512		759
513	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
514	$cv->begin;	761	$cv->begin;
515	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
516	$result{$host} = ...;	763	$result{$host} = ...;
…		…
531	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
532	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
533	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
534	doesn't execute once).	781	doesn't execute once).
535		782
536	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
537	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
538	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
539	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
540		788
541	=back	789	=back
542		790
543	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
544		792
…		…
548	=over 4	796	=over 4
549		797
550	=item $cv->recv	798	=item $cv->recv
551		799
552	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
553	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
554	normally.	802	normally.
555		803
556	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
557	will return immediately.	805	will return immediately.
558		806
…		…
560	function will call C<croak>.	808	function will call C<croak>.
561		809
562	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
563	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
564		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
565	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
566	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
567	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
568	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
569	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
570	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
571	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
572		827
573	Another reason I<never> to C<< ->recv >> in a module is that you cannot
574	sensibly have two C<< ->recv >>'s in parallel, as that would require
575	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
576	can supply.
577
578	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
579	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
580	versions and also integrates coroutines into AnyEvent, making blocking
581	C<< ->recv >> calls perfectly safe as long as they are done from another
582	coroutine (one that doesn't run the event loop).
583
584	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
585	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
586	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
587	waits otherwise.	831	waits otherwise.
588		832
589	=item $bool = $cv->ready	833	=item $bool = $cv->ready
590		834
591	Returns true when the condition is "true", i.e. whether C<send> or	835	Returns true when the condition is "true", i.e. whether C<send> or
592	C<croak> have been called.	836	C<croak> have been called.
593		837
594	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
595		839
596	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
597	replaces it before doing so.	841	replaces it before doing so.
598		842
599	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
600	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
601	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
602	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
603		848
604	=back	849	=back
605		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
606	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
607		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
608	=over 4	919	=over 4
609		920
610	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
611		922
612	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
613	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
614	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
615	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
616	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
617		930	will be C<urxvt::anyevent>).
618	The known classes so far are:
619
620	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
621	AnyEvent::Impl::Event based on Event, second best choice.
622	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
623	AnyEvent::Impl::Glib based on Glib, third-best choice.
624	AnyEvent::Impl::Tk based on Tk, very bad choice.
625	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
626	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
627	AnyEvent::Impl::POE based on POE, not generic enough for full support.
628
629	There is no support for WxWidgets, as WxWidgets has no support for
630	watching file handles. However, you can use WxWidgets through the
631	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
632	second, which was considered to be too horrible to even consider for
633	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
634	it's adaptor.
635
636	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
637	autodetecting them.
638		931
639	=item AnyEvent::detect	932	=item AnyEvent::detect
640		933
641	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
642	if necessary. You should only call this function right before you would	935	if necessary. You should only call this function right before you would
643	have created an AnyEvent watcher anyway, that is, as late as possible at	936	have created an AnyEvent watcher anyway, that is, as late as possible at
644	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	If you need to do some initialisation before AnyEvent watchers are
		940	created, use C<post_detect>.
645		941
646	=item $guard = AnyEvent::post_detect { BLOCK }	942	=item $guard = AnyEvent::post_detect { BLOCK }
647		943
648	Arranges for the code block to be executed as soon as the event model is	944	Arranges for the code block to be executed as soon as the event model is
649	autodetected (or immediately if this has already happened).	945	autodetected (or immediately if that has already happened).
		946
		947	The block will be executed I<after> the actual backend has been detected
		948	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		949	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		950	other initialisations - see the sources of L<AnyEvent::Strict> or
		951	L<AnyEvent::AIO> to see how this is used.
		952
		953	The most common usage is to create some global watchers, without forcing
		954	event module detection too early, for example, L<AnyEvent::AIO> creates
		955	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		956	avoid autodetecting the event module at load time.
650		957
651	If called in scalar or list context, then it creates and returns an object	958	If called in scalar or list context, then it creates and returns an object
652	that automatically removes the callback again when it is destroyed. See	959	that automatically removes the callback again when it is destroyed (or
		960	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
653	L<Coro::BDB> for a case where this is useful.	961	a case where this is useful.
		962
		963	Example: Create a watcher for the IO::AIO module and store it in
		964	C<$WATCHER>, but do so only do so after the event loop is initialised.
		965
		966	our WATCHER;
		967
		968	my $guard = AnyEvent::post_detect {
		969	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		970	};
		971
		972	# the ||= is important in case post_detect immediately runs the block,
		973	# as to not clobber the newly-created watcher. assigning both watcher and
		974	# post_detect guard to the same variable has the advantage of users being
		975	# able to just C<undef $WATCHER> if the watcher causes them grief.
		976
		977	$WATCHER ||= $guard;
654		978
655	=item @AnyEvent::post_detect	979	=item @AnyEvent::post_detect
656		980
657	If there are any code references in this array (you can C<push> to it	981	If there are any code references in this array (you can C<push> to it
658	before or after loading AnyEvent), then they will called directly after	982	before or after loading AnyEvent), then they will be called directly
659	the event loop has been chosen.	983	after the event loop has been chosen.
660		984
661	You should check C<$AnyEvent::MODEL> before adding to this array, though:	985	You should check C<$AnyEvent::MODEL> before adding to this array, though:
662	if it contains a true value then the event loop has already been detected,	986	if it is defined then the event loop has already been detected, and the
663	and the array will be ignored.	987	array will be ignored.
664		988
665	Best use C<AnyEvent::post_detect { BLOCK }> instead.	989	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		990	it, as it takes care of these details.
		991
		992	This variable is mainly useful for modules that can do something useful
		993	when AnyEvent is used and thus want to know when it is initialised, but do
		994	not need to even load it by default. This array provides the means to hook
		995	into AnyEvent passively, without loading it.
		996
		997	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		998	together, you could put this into Coro (this is the actual code used by
		999	Coro to accomplish this):
		1000
		1001	if (defined $AnyEvent::MODEL) {
		1002	# AnyEvent already initialised, so load Coro::AnyEvent
		1003	require Coro::AnyEvent;
		1004	} else {
		1005	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1006	# as soon as it is
		1007	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1008	}
		1009
		1010	=item AnyEvent::postpone { BLOCK }
		1011
		1012	Arranges for the block to be executed as soon as possible, but not before
		1013	the call itself returns. In practise, the block will be executed just
		1014	before the event loop polls for new events, or shortly afterwards.
		1015
		1016	This function never returns anything (to make the C<return postpone { ...
		1017	}> idiom more useful.
		1018
		1019	To understand the usefulness of this function, consider a function that
		1020	asynchronously does something for you and returns some transaction
		1021	object or guard to let you cancel the operation. For example,
		1022	C<AnyEvent::Socket::tcp_connect>:
		1023
		1024	# start a conenction attempt unless one is active
		1025	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1026	delete $self->{connect_guard};
		1027	...
		1028	};
		1029
		1030	Imagine that this function could instantly call the callback, for
		1031	example, because it detects an obvious error such as a negative port
		1032	number. Invoking the callback before the function returns causes problems
		1033	however: the callback will be called and will try to delete the guard
		1034	object. But since the function hasn't returned yet, there is nothing to
		1035	delete. When the function eventually returns it will assign the guard
		1036	object to C<< $self->{connect_guard} >>, where it will likely never be
		1037	deleted, so the program thinks it is still trying to connect.
		1038
		1039	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1040	callback directly on error:
		1041
		1042	$cb->(undef), return # signal error to callback, BAD!
		1043	if $some_error_condition;
		1044
		1045	It should use C<postpone>:
		1046
		1047	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1048	if $some_error_condition;
666		1049
667	=back	1050	=back
668		1051
669	=head1 WHAT TO DO IN A MODULE	1052	=head1 WHAT TO DO IN A MODULE
670		1053
…		…
681	because it will stall the whole program, and the whole point of using	1064	because it will stall the whole program, and the whole point of using
682	events is to stay interactive.	1065	events is to stay interactive.
683		1066
684	It is fine, however, to call C<< ->recv >> when the user of your module	1067	It is fine, however, to call C<< ->recv >> when the user of your module
685	requests it (i.e. if you create a http request object ad have a method	1068	requests it (i.e. if you create a http request object ad have a method
686	called C<results> that returns the results, it should call C<< ->recv >>	1069	called C<results> that returns the results, it may call C<< ->recv >>
687	freely, as the user of your module knows what she is doing. always).	1070	freely, as the user of your module knows what she is doing. Always).
688		1071
689	=head1 WHAT TO DO IN THE MAIN PROGRAM	1072	=head1 WHAT TO DO IN THE MAIN PROGRAM
690		1073
691	There will always be a single main program - the only place that should	1074	There will always be a single main program - the only place that should
692	dictate which event model to use.	1075	dictate which event model to use.
693		1076
694	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1077	If the program is not event-based, it need not do anything special, even
695	do anything special (it does not need to be event-based) and let AnyEvent	1078	when it depends on a module that uses an AnyEvent. If the program itself
696	decide which implementation to chose if some module relies on it.	1079	uses AnyEvent, but does not care which event loop is used, all it needs
		1080	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1081	available loop implementation.
697		1082
698	If the main program relies on a specific event model - for example, in	1083	If the main program relies on a specific event model - for example, in
699	Gtk2 programs you have to rely on the Glib module - you should load the	1084	Gtk2 programs you have to rely on the Glib module - you should load the
700	event module before loading AnyEvent or any module that uses it: generally	1085	event module before loading AnyEvent or any module that uses it: generally
701	speaking, you should load it as early as possible. The reason is that	1086	speaking, you should load it as early as possible. The reason is that
702	modules might create watchers when they are loaded, and AnyEvent will	1087	modules might create watchers when they are loaded, and AnyEvent will
703	decide on the event model to use as soon as it creates watchers, and it	1088	decide on the event model to use as soon as it creates watchers, and it
704	might chose the wrong one unless you load the correct one yourself.	1089	might choose the wrong one unless you load the correct one yourself.
705		1090
706	You can chose to use a pure-perl implementation by loading the	1091	You can chose to use a pure-perl implementation by loading the
707	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1092	C<AnyEvent::Loop> module, which gives you similar behaviour
708	everywhere, but letting AnyEvent chose the model is generally better.	1093	everywhere, but letting AnyEvent chose the model is generally better.
709		1094
710	=head2 MAINLOOP EMULATION	1095	=head2 MAINLOOP EMULATION
711		1096
712	Sometimes (often for short test scripts, or even standalone programs who	1097	Sometimes (often for short test scripts, or even standalone programs who
…		…
725		1110
726		1111
727	=head1 OTHER MODULES	1112	=head1 OTHER MODULES
728		1113
729	The following is a non-exhaustive list of additional modules that use	1114	The following is a non-exhaustive list of additional modules that use
730	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1115	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
731	in the same program. Some of the modules come with AnyEvent, some are	1116	modules and other event loops in the same program. Some of the modules
732	available via CPAN.	1117	come as part of AnyEvent, the others are available via CPAN.
733		1118
734	=over 4	1119	=over 4
735		1120
736	=item L<AnyEvent::Util>	1121	=item L<AnyEvent::Util>
737		1122
738	Contains various utility functions that replace often-used but blocking	1123	Contains various utility functions that replace often-used blocking
739	functions such as C<inet_aton> by event-/callback-based versions.	1124	functions such as C<inet_aton> with event/callback-based versions.
740		1125
741	=item L<AnyEvent::Socket>	1126	=item L<AnyEvent::Socket>
742		1127
743	Provides various utility functions for (internet protocol) sockets,	1128	Provides various utility functions for (internet protocol) sockets,
744	addresses and name resolution. Also functions to create non-blocking tcp	1129	addresses and name resolution. Also functions to create non-blocking tcp
…		…
746		1131
747	=item L<AnyEvent::Handle>	1132	=item L<AnyEvent::Handle>
748		1133
749	Provide read and write buffers, manages watchers for reads and writes,	1134	Provide read and write buffers, manages watchers for reads and writes,
750	supports raw and formatted I/O, I/O queued and fully transparent and	1135	supports raw and formatted I/O, I/O queued and fully transparent and
751	non-blocking SSL/TLS.	1136	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
752		1137
753	=item L<AnyEvent::DNS>	1138	=item L<AnyEvent::DNS>
754		1139
755	Provides rich asynchronous DNS resolver capabilities.	1140	Provides rich asynchronous DNS resolver capabilities.
756		1141
		1142	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1143
		1144	Implement event-based interfaces to the protocols of the same name (for
		1145	the curious, IGS is the International Go Server and FCP is the Freenet
		1146	Client Protocol).
		1147
		1148	=item L<AnyEvent::Handle::UDP>
		1149
		1150	Here be danger!
		1151
		1152	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1153	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1154	its use of a stream-based API with a protocol that isn't streamable, that
		1155	the only way to improve it is to delete it.
		1156
		1157	It features data corruption (but typically only under load) and general
		1158	confusion. On top, the author is not only clueless about UDP but also
		1159	fact-resistant - some gems of his understanding: "connect doesn't work
		1160	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1161	packets", "I don't need to implement proper error checking as UDP doesn't
		1162	support error checking" and so on - he doesn't even understand what's
		1163	wrong with his module when it is explained to him.
		1164
757	=item L<AnyEvent::HTTP>	1165	=item L<AnyEvent::DBI>
758		1166
759	A simple-to-use HTTP library that is capable of making a lot of concurrent	1167	Executes L<DBI> requests asynchronously in a proxy process for you,
760	HTTP requests.	1168	notifying you in an event-based way when the operation is finished.
		1169
		1170	=item L<AnyEvent::AIO>
		1171
		1172	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1173	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1174	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1175	file I/O, and much more.
761		1176
762	=item L<AnyEvent::HTTPD>	1177	=item L<AnyEvent::HTTPD>
763		1178
764	Provides a simple web application server framework.	1179	A simple embedded webserver.
765		1180
766	=item L<AnyEvent::FastPing>	1181	=item L<AnyEvent::FastPing>
767		1182
768	The fastest ping in the west.	1183	The fastest ping in the west.
769		1184
770	=item L<AnyEvent::DBI>
771
772	Executes L<DBI> requests asynchronously in a proxy process.
773
774	=item L<AnyEvent::AIO>
775
776	Truly asynchronous I/O, should be in the toolbox of every event
777	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
778	together.
779
780	=item L<AnyEvent::BDB>
781
782	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
783	L<BDB> and AnyEvent together.
784
785	=item L<AnyEvent::GPSD>
786
787	A non-blocking interface to gpsd, a daemon delivering GPS information.
788
789	=item L<AnyEvent::IGS>
790
791	A non-blocking interface to the Internet Go Server protocol (used by
792	L<App::IGS>).
793
794	=item L<Net::IRC3>
795
796	AnyEvent based IRC client module family.
797
798	=item L<Net::XMPP2>
799
800	AnyEvent based XMPP (Jabber protocol) module family.
801
802	=item L<Net::FCP>
803
804	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
805	of AnyEvent.
806
807	=item L<Event::ExecFlow>
808
809	High level API for event-based execution flow control.
810
811	=item L<Coro>	1185	=item L<Coro>
812		1186
813	Has special support for AnyEvent via L<Coro::AnyEvent>.	1187	Has special support for AnyEvent via L<Coro::AnyEvent>.
814		1188
815	=item L<IO::Lambda>
816
817	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
818
819	=back	1189	=back
820		1190
821	=cut	1191	=cut
822		1192
823	package AnyEvent;	1193	package AnyEvent;
824		1194
825	no warnings;	1195	# basically a tuned-down version of common::sense
826	use strict;	1196	sub common_sense {
		1197	# from common:.sense 3.4
		1198	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1199	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1200	$^H |= 0x00000600;
		1201	}
827		1202
		1203	BEGIN { AnyEvent::common_sense }
		1204
828	use Carp;	1205	use Carp ();
829		1206
830	our $VERSION = 4.2;	1207	our $VERSION = '5.34';
831	our $MODEL;	1208	our $MODEL;
832		1209
833	our $AUTOLOAD;	1210	our $AUTOLOAD;
834	our @ISA;	1211	our @ISA;
835		1212
836	our @REGISTRY;	1213	our @REGISTRY;
837		1214
838	our $WIN32;	1215	our $VERBOSE;
839		1216
840	BEGIN {	1217	BEGIN {
841	my $win32 = ! ! ($^O =~ /mswin32/i);	1218	require "AnyEvent/constants.pl";
842	eval "sub WIN32(){ $win32 }";
843	}
844		1219
		1220	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1221
		1222	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1223	if ${^TAINT};
		1224
845	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1225	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1226
		1227	}
		1228
		1229	our $MAX_SIGNAL_LATENCY = 10;
846		1230
847	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1231	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
848		1232
849	{	1233	{
850	my $idx;	1234	my $idx;
851	$PROTOCOL{$_} = ++$idx	1235	$PROTOCOL{$_} = ++$idx
852	for reverse split /\s*,\s*/,	1236	for reverse split /\s*,\s*/,
853	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1237	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
854	}	1238	}
855		1239
		1240	our @post_detect;
		1241
		1242	sub post_detect(&) {
		1243	my ($cb) = @_;
		1244
		1245	push @post_detect, $cb;
		1246
		1247	defined wantarray
		1248	? bless \$cb, "AnyEvent::Util::postdetect"
		1249	: ()
		1250	}
		1251
		1252	sub AnyEvent::Util::postdetect::DESTROY {
		1253	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1254	}
		1255
		1256	our $POSTPONE_W;
		1257	our @POSTPONE;
		1258
		1259	sub _postpone_exec {
		1260	undef $POSTPONE_W;
		1261
		1262	&{ shift @POSTPONE }
		1263	while @POSTPONE;
		1264	}
		1265
		1266	sub postpone(&) {
		1267	push @POSTPONE, shift;
		1268
		1269	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1270
		1271	()
		1272	}
		1273
856	my @models = (	1274	our @models = (
857	[EV:: => AnyEvent::Impl::EV::],	1275	[EV:: => AnyEvent::Impl::EV:: , 1],
858	[Event:: => AnyEvent::Impl::Event::],	1276	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
859	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
860	# everything below here will not be autoprobed	1277	# everything below here will not (normally) be autoprobed
861	# as the pureperl backend should work everywhere	1278	# as the pure perl backend should work everywhere
862	# and is usually faster	1279	# and is usually faster
		1280	[Event:: => AnyEvent::Impl::Event::, 1],
		1281	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1282	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1283	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
863	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1284	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
864	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
865	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
866	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1285	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
867	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1286	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
868	[Wx:: => AnyEvent::Impl::POE::],	1287	[Wx:: => AnyEvent::Impl::POE::],
869	[Prima:: => AnyEvent::Impl::POE::],	1288	[Prima:: => AnyEvent::Impl::POE::],
		1289	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1290	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1291	[FLTK:: => AnyEvent::Impl::FLTK2::],
870	);	1292	);
871		1293
872	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
873
874	our @post_detect;
875
876	sub post_detect(&) {	1294	sub detect() {
877	my ($cb) = @_;	1295	# free some memory
		1296	*detect = sub () { $MODEL };
878		1297
879	if ($MODEL) {	1298	local $!; # for good measure
880	$cb->();	1299	local $SIG{__DIE__};
881		1300
882	1	1301	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1302	my $model = $1;
		1303	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1304	if (eval "require $model") {
		1305	$MODEL = $model;
		1306	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
883	} else {	1307	} else {
884	push @post_detect, $cb;	1308	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
885		1309	}
886	defined wantarray
887	? bless \$cb, "AnyEvent::Util::PostDetect"
888	: ()
889	}	1310	}
890	}
891		1311
892	sub AnyEvent::Util::PostDetect::DESTROY {	1312	# check for already loaded models
893	@post_detect = grep $_ != ${$_[0]}, @post_detect;
894	}
895
896	sub detect() {
897	unless ($MODEL) {	1313	unless ($MODEL) {
898	no strict 'refs';	1314	for (@REGISTRY, @models) {
899	local $SIG{__DIE__};	1315	my ($package, $model) = @$_;
900		1316	if (${"$package\::VERSION"} > 0) {
901	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
902	my $model = "AnyEvent::Impl::$1";
903	if (eval "require $model") {	1317	if (eval "require $model") {
904	$MODEL = $model;	1318	$MODEL = $model;
905	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1319	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
906	} else {	1320	last;
907	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1321	}
908	}	1322	}
909	}	1323	}
910		1324
911	# check for already loaded models
912	unless ($MODEL) {	1325	unless ($MODEL) {
		1326	# try to autoload a model
913	for (@REGISTRY, @models) {	1327	for (@REGISTRY, @models) {
914	my ($package, $model) = @$_;	1328	my ($package, $model, $autoload) = @$_;
		1329	if (
		1330	$autoload
		1331	and eval "require $package"
915	if (${"$package\::VERSION"} > 0) {	1332	and ${"$package\::VERSION"} > 0
916	if (eval "require $model") {	1333	and eval "require $model"
		1334	) {
917	$MODEL = $model;	1335	$MODEL = $model;
918	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1336	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
919	last;	1337	last;
920	}
921	}	1338	}
922	}	1339	}
923		1340
924	unless ($MODEL) {
925	# try to load a model
926
927	for (@REGISTRY, @models) {
928	my ($package, $model) = @$_;
929	if (eval "require $package"
930	and ${"$package\::VERSION"} > 0
931	and eval "require $model") {
932	$MODEL = $model;
933	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
934	last;
935	}
936	}
937
938	$MODEL	1341	$MODEL
939	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1342	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
940	}
941	}	1343	}
942
943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
944
945	if ($ENV{PERL_ANYEVENT_STRICT}) {
946	unshift @AnyEvent::Base::Strict::ISA, $MODEL;
947	unshift @ISA, AnyEvent::Base::Strict::
948	} else {
949	unshift @ISA, $MODEL;
950	}
951
952	(shift @post_detect)->() while @post_detect;
953	}	1344	}
954		1345
		1346	# free memory only needed for probing
		1347	undef @models;
		1348	undef @REGISTRY;
		1349
		1350	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1351	unshift @ISA, $MODEL;
		1352
		1353	# now nuke some methods that are overridden by the backend.
		1354	# SUPER usage is not allowed in these.
		1355	for (qw(time signal child idle)) {
		1356	undef &{"AnyEvent::Base::$_"}
		1357	if defined &{"$MODEL\::$_"};
		1358	}
		1359
		1360	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1361	eval { require AnyEvent::Strict };
		1362	warn "AnyEvent: cannot load AnyEvent::Strict: $@"
		1363	if $@ && $VERBOSE;
		1364	}
		1365
		1366	(shift @post_detect)->() while @post_detect;
		1367	undef @post_detect;
		1368
		1369	*post_detect = sub(&) {
		1370	shift->();
		1371
		1372	undef
		1373	};
		1374
		1375	# recover a few more bytes
		1376	postpone {
		1377	undef &AUTOLOAD;
		1378	};
		1379
955	$MODEL	1380	$MODEL
956	}	1381	}
		1382
		1383	our %method = map +($_ => 1),
		1384	qw(io timer time now now_update signal child idle condvar DESTROY);
957		1385
958	sub AUTOLOAD {	1386	sub AUTOLOAD {
959	(my $func = $AUTOLOAD) =~ s/.*://;	1387	(my $func = $AUTOLOAD) =~ s/.*://;
960		1388
961	$method{$func}	1389	$method{$func}
962	or croak "$func: not a valid method for AnyEvent objects";	1390	or Carp::croak "$func: not a valid AnyEvent class method";
963		1391
964	detect unless $MODEL;	1392	# free some memory
		1393	undef %method;
		1394
		1395	detect;
965		1396
966	my $class = shift;	1397	my $class = shift;
967	$class->$func (@_);	1398	$class->$func (@_);
968	}	1399	}
969		1400
		1401	# utility function to dup a filehandle. this is used by many backends
		1402	# to support binding more than one watcher per filehandle (they usually
		1403	# allow only one watcher per fd, so we dup it to get a different one).
		1404	sub _dupfh($$;$$) {
		1405	my ($poll, $fh, $r, $w) = @_;
		1406
		1407	# cygwin requires the fh mode to be matching, unix doesn't
		1408	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1409
		1410	open my $fh2, $mode, $fh
		1411	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1412
		1413	# we assume CLOEXEC is already set by perl in all important cases
		1414
		1415	($fh2, $rw)
		1416	}
		1417
		1418	=head1 SIMPLIFIED AE API
		1419
		1420	Starting with version 5.0, AnyEvent officially supports a second, much
		1421	simpler, API that is designed to reduce the calling, typing and memory
		1422	overhead by using function call syntax and a fixed number of parameters.
		1423
		1424	See the L<AE> manpage for details.
		1425
		1426	=cut
		1427
		1428	package AE;
		1429
		1430	our $VERSION = $AnyEvent::VERSION;
		1431
		1432
		1433	sub _reset() {
		1434	eval q{
		1435	# fall back to the main API by default - backends and AnyEvent::Base
		1436	# implementations can overwrite these.
		1437
		1438	sub io($$$) {
		1439	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1440	}
		1441
		1442	sub timer($$$) {
		1443	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1444	}
		1445
		1446	sub signal($$) {
		1447	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1448	}
		1449
		1450	sub child($$) {
		1451	AnyEvent->child (pid => $_[0], cb => $_[1])
		1452	}
		1453
		1454	sub idle($) {
		1455	AnyEvent->idle (cb => $_[0])
		1456	}
		1457
		1458	sub cv(;&) {
		1459	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1460	}
		1461
		1462	sub now() {
		1463	AnyEvent->now
		1464	}
		1465
		1466	sub now_update() {
		1467	AnyEvent->now_update
		1468	}
		1469
		1470	sub time() {
		1471	AnyEvent->time
		1472	}
		1473
		1474	*postpone = \&AnyEvent::postpone;
		1475	};
		1476	die if $@;
		1477	}
		1478
		1479	BEGIN { _reset }
		1480
970	package AnyEvent::Base;	1481	package AnyEvent::Base;
971		1482
972	# default implementation for now and time	1483	# default implementations for many methods
973		1484
974	use Time::HiRes ();	1485	sub time {
		1486	eval q{ # poor man's autoloading {}
		1487	# probe for availability of Time::HiRes
		1488	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1489	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1490	*AE::time = \&Time::HiRes::time;
		1491	# if (eval "use POSIX (); (POSIX::times())...
		1492	} else {
		1493	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1494	*AE::time = sub (){ time }; # epic fail
		1495	}
975		1496
976	sub time { Time::HiRes::time }	1497	*time = sub { AE::time }; # different prototypes
977	sub now { Time::HiRes::time }	1498	};
		1499	die if $@;
		1500
		1501	&time
		1502	}
		1503
		1504	*now = \&time;
		1505
		1506	sub now_update { }
		1507
		1508	sub _poll {
		1509	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1510	}
978		1511
979	# default implementation for ->condvar	1512	# default implementation for ->condvar
		1513	# in fact, the default should not be overwritten
980		1514
981	sub condvar {	1515	sub condvar {
		1516	eval q{ # poor man's autoloading {}
		1517	*condvar = sub {
982	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1518	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1519	};
		1520
		1521	*AE::cv = sub (;&) {
		1522	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1523	};
		1524	};
		1525	die if $@;
		1526
		1527	&condvar
983	}	1528	}
984		1529
985	# default implementation for ->signal	1530	# default implementation for ->signal
986		1531
987	our %SIG_CB;	1532	our $HAVE_ASYNC_INTERRUPT;
		1533
		1534	sub _have_async_interrupt() {
		1535	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1536	&& eval "use Async::Interrupt 1.02 (); 1")
		1537	unless defined $HAVE_ASYNC_INTERRUPT;
		1538
		1539	$HAVE_ASYNC_INTERRUPT
		1540	}
		1541
		1542	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1543	our (%SIG_ASY, %SIG_ASY_W);
		1544	our ($SIG_COUNT, $SIG_TW);
		1545
		1546	# install a dummy wakeup watcher to reduce signal catching latency
		1547	# used by Impls
		1548	sub _sig_add() {
		1549	unless ($SIG_COUNT++) {
		1550	# try to align timer on a full-second boundary, if possible
		1551	my $NOW = AE::now;
		1552
		1553	$SIG_TW = AE::timer
		1554	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1555	$MAX_SIGNAL_LATENCY,
		1556	sub { } # just for the PERL_ASYNC_CHECK
		1557	;
		1558	}
		1559	}
		1560
		1561	sub _sig_del {
		1562	undef $SIG_TW
		1563	unless --$SIG_COUNT;
		1564	}
		1565
		1566	our $_sig_name_init; $_sig_name_init = sub {
		1567	eval q{ # poor man's autoloading {}
		1568	undef $_sig_name_init;
		1569
		1570	if (_have_async_interrupt) {
		1571	*sig2num = \&Async::Interrupt::sig2num;
		1572	*sig2name = \&Async::Interrupt::sig2name;
		1573	} else {
		1574	require Config;
		1575
		1576	my %signame2num;
		1577	@signame2num{ split ' ', $Config::Config{sig_name} }
		1578	= split ' ', $Config::Config{sig_num};
		1579
		1580	my @signum2name;
		1581	@signum2name[values %signame2num] = keys %signame2num;
		1582
		1583	*sig2num = sub($) {
		1584	$_[0] > 0 ? shift : $signame2num{+shift}
		1585	};
		1586	*sig2name = sub ($) {
		1587	$_[0] > 0 ? $signum2name[+shift] : shift
		1588	};
		1589	}
		1590	};
		1591	die if $@;
		1592	};
		1593
		1594	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1595	sub sig2name($) { &$_sig_name_init; &sig2name }
988		1596
989	sub signal {	1597	sub signal {
		1598	eval q{ # poor man's autoloading {}
		1599	# probe for availability of Async::Interrupt
		1600	if (_have_async_interrupt) {
		1601	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1602
		1603	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1604	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1605
		1606	} else {
		1607	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1608
		1609	if (AnyEvent::WIN32) {
		1610	require AnyEvent::Util;
		1611
		1612	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1613	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1614	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1615	} else {
		1616	pipe $SIGPIPE_R, $SIGPIPE_W;
		1617	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1618	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1619
		1620	# not strictly required, as $^F is normally 2, but let's make sure...
		1621	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1622	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1623	}
		1624
		1625	$SIGPIPE_R
		1626	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1627
		1628	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1629	}
		1630
		1631	*signal = $HAVE_ASYNC_INTERRUPT
		1632	? sub {
990	my (undef, %arg) = @_;	1633	my (undef, %arg) = @_;
991		1634
		1635	# async::interrupt
992	my $signal = uc $arg{signal}	1636	my $signal = sig2num $arg{signal};
993	or Carp::croak "required option 'signal' is missing";
994
995	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1637	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1638
		1639	$SIG_ASY{$signal} ||= new Async::Interrupt
		1640	cb => sub { undef $SIG_EV{$signal} },
		1641	signal => $signal,
		1642	pipe => [$SIGPIPE_R->filenos],
		1643	pipe_autodrain => 0,
		1644	;
		1645
		1646	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1647	}
		1648	: sub {
		1649	my (undef, %arg) = @_;
		1650
		1651	# pure perl
		1652	my $signal = sig2name $arg{signal};
		1653	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1654
996	$SIG{$signal} ||= sub {	1655	$SIG{$signal} ||= sub {
		1656	local $!;
		1657	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1658	undef $SIG_EV{$signal};
		1659	};
		1660
		1661	# can't do signal processing without introducing races in pure perl,
		1662	# so limit the signal latency.
		1663	_sig_add;
		1664
		1665	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1666	}
		1667	;
		1668
		1669	*AnyEvent::Base::signal::DESTROY = sub {
		1670	my ($signal, $cb) = @{$_[0]};
		1671
		1672	_sig_del;
		1673
		1674	delete $SIG_CB{$signal}{$cb};
		1675
		1676	$HAVE_ASYNC_INTERRUPT
		1677	? delete $SIG_ASY{$signal}
		1678	: # delete doesn't work with older perls - they then
		1679	# print weird messages, or just unconditionally exit
		1680	# instead of getting the default action.
		1681	undef $SIG{$signal}
		1682	unless keys %{ $SIG_CB{$signal} };
		1683	};
		1684
		1685	*_signal_exec = sub {
		1686	$HAVE_ASYNC_INTERRUPT
		1687	? $SIGPIPE_R->drain
		1688	: sysread $SIGPIPE_R, (my $dummy), 9;
		1689
		1690	while (%SIG_EV) {
		1691	for (keys %SIG_EV) {
		1692	delete $SIG_EV{$_};
997	$_->() for values %{ $SIG_CB{$signal} || {} };	1693	&$_ for values %{ $SIG_CB{$_} || {} };
		1694	}
		1695	}
		1696	};
998	};	1697	};
		1698	die if $@;
999		1699
1000	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1700	&signal
1001	}
1002
1003	sub AnyEvent::Base::Signal::DESTROY {
1004	my ($signal, $cb) = @{$_[0]};
1005
1006	delete $SIG_CB{$signal}{$cb};
1007
1008	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1009	}	1701	}
1010		1702
1011	# default implementation for ->child	1703	# default implementation for ->child
1012		1704
1013	our %PID_CB;	1705	our %PID_CB;
1014	our $CHLD_W;	1706	our $CHLD_W;
1015	our $CHLD_DELAY_W;	1707	our $CHLD_DELAY_W;
1016	our $PID_IDLE;
1017	our $WNOHANG;
1018		1708
1019	sub _child_wait {	1709	# used by many Impl's
1020	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1710	sub _emit_childstatus($$) {
		1711	my (undef, $rpid, $rstatus) = @_;
		1712
		1713	$_->($rpid, $rstatus)
1021	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1714	for values %{ $PID_CB{$rpid} || {} },
1022	(values %{ $PID_CB{0} || {} });	1715	values %{ $PID_CB{0} || {} };
1023	}
1024
1025	undef $PID_IDLE;
1026	}
1027
1028	sub _sigchld {
1029	# make sure we deliver these changes "synchronous" with the event loop.
1030	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1031	undef $CHLD_DELAY_W;
1032	&_child_wait;
1033	});
1034	}	1716	}
1035		1717
1036	sub child {	1718	sub child {
		1719	eval q{ # poor man's autoloading {}
		1720	*_sigchld = sub {
		1721	my $pid;
		1722
		1723	AnyEvent->_emit_childstatus ($pid, $?)
		1724	while ($pid = waitpid -1, WNOHANG) > 0;
		1725	};
		1726
		1727	*child = sub {
1037	my (undef, %arg) = @_;	1728	my (undef, %arg) = @_;
1038		1729
1039	defined (my $pid = $arg{pid} + 0)	1730	my $pid = $arg{pid};
1040	or Carp::croak "required option 'pid' is missing";	1731	my $cb = $arg{cb};
1041		1732
1042	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1733	$PID_CB{$pid}{$cb+0} = $cb;
1043		1734
1044	unless ($WNOHANG) {
1045	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1046	}
1047
1048	unless ($CHLD_W) {	1735	unless ($CHLD_W) {
1049	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1736	$CHLD_W = AE::signal CHLD => \&_sigchld;
1050	# child could be a zombie already, so make at least one round	1737	# child could be a zombie already, so make at least one round
1051	&_sigchld;	1738	&_sigchld;
1052	}	1739	}
1053		1740
1054	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1741	bless [$pid, $cb+0], "AnyEvent::Base::child"
1055	}	1742	};
1056		1743
1057	sub AnyEvent::Base::Child::DESTROY {	1744	*AnyEvent::Base::child::DESTROY = sub {
1058	my ($pid, $cb) = @{$_[0]};	1745	my ($pid, $icb) = @{$_[0]};
1059		1746
1060	delete $PID_CB{$pid}{$cb};	1747	delete $PID_CB{$pid}{$icb};
1061	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1748	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1062		1749
1063	undef $CHLD_W unless keys %PID_CB;	1750	undef $CHLD_W unless keys %PID_CB;
		1751	};
		1752	};
		1753	die if $@;
		1754
		1755	&child
		1756	}
		1757
		1758	# idle emulation is done by simply using a timer, regardless
		1759	# of whether the process is idle or not, and not letting
		1760	# the callback use more than 50% of the time.
		1761	sub idle {
		1762	eval q{ # poor man's autoloading {}
		1763	*idle = sub {
		1764	my (undef, %arg) = @_;
		1765
		1766	my ($cb, $w, $rcb) = $arg{cb};
		1767
		1768	$rcb = sub {
		1769	if ($cb) {
		1770	$w = AE::time;
		1771	&$cb;
		1772	$w = AE::time - $w;
		1773
		1774	# never use more then 50% of the time for the idle watcher,
		1775	# within some limits
		1776	$w = 0.0001 if $w < 0.0001;
		1777	$w = 5 if $w > 5;
		1778
		1779	$w = AE::timer $w, 0, $rcb;
		1780	} else {
		1781	# clean up...
		1782	undef $w;
		1783	undef $rcb;
		1784	}
		1785	};
		1786
		1787	$w = AE::timer 0.05, 0, $rcb;
		1788
		1789	bless \\$cb, "AnyEvent::Base::idle"
		1790	};
		1791
		1792	*AnyEvent::Base::idle::DESTROY = sub {
		1793	undef $${$_[0]};
		1794	};
		1795	};
		1796	die if $@;
		1797
		1798	&idle
1064	}	1799	}
1065		1800
1066	package AnyEvent::CondVar;	1801	package AnyEvent::CondVar;
1067		1802
1068	our @ISA = AnyEvent::CondVar::Base::;	1803	our @ISA = AnyEvent::CondVar::Base::;
1069		1804
		1805	# only to be used for subclassing
		1806	sub new {
		1807	my $class = shift;
		1808	bless AnyEvent->condvar (@_), $class
		1809	}
		1810
1070	package AnyEvent::CondVar::Base;	1811	package AnyEvent::CondVar::Base;
1071		1812
1072	use overload	1813	#use overload
1073	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1814	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1074	fallback => 1;	1815	# fallback => 1;
		1816
		1817	# save 300+ kilobytes by dirtily hardcoding overloading
		1818	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1819	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1820	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1821	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1822
		1823	our $WAITING;
1075		1824
1076	sub _send {	1825	sub _send {
1077	# nop	1826	# nop
		1827	}
		1828
		1829	sub _wait {
		1830	AnyEvent->_poll until $_[0]{_ae_sent};
1078	}	1831	}
1079		1832
1080	sub send {	1833	sub send {
1081	my $cv = shift;	1834	my $cv = shift;
1082	$cv->{_ae_sent} = [@_];	1835	$cv->{_ae_sent} = [@_];
…		…
1091		1844
1092	sub ready {	1845	sub ready {
1093	$_[0]{_ae_sent}	1846	$_[0]{_ae_sent}
1094	}	1847	}
1095		1848
1096	sub _wait {
1097	AnyEvent->one_event while !$_[0]{_ae_sent};
1098	}
1099
1100	sub recv {	1849	sub recv {
		1850	unless ($_[0]{_ae_sent}) {
		1851	$WAITING
		1852	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1853
		1854	local $WAITING = 1;
1101	$_[0]->_wait;	1855	$_[0]->_wait;
		1856	}
1102		1857
1103	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1858	$_[0]{_ae_croak}
1104	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1859	and Carp::croak $_[0]{_ae_croak};
		1860
		1861	wantarray
		1862	? @{ $_[0]{_ae_sent} }
		1863	: $_[0]{_ae_sent}[0]
1105	}	1864	}
1106		1865
1107	sub cb {	1866	sub cb {
1108	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1867	my $cv = shift;
		1868
		1869	@_
		1870	and $cv->{_ae_cb} = shift
		1871	and $cv->{_ae_sent}
		1872	and (delete $cv->{_ae_cb})->($cv);
		1873
1109	$_[0]{_ae_cb}	1874	$cv->{_ae_cb}
1110	}	1875	}
1111		1876
1112	sub begin {	1877	sub begin {
1113	++$_[0]{_ae_counter};	1878	++$_[0]{_ae_counter};
1114	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1879	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1119	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1884	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1120	}	1885	}
1121		1886
1122	# undocumented/compatibility with pre-3.4	1887	# undocumented/compatibility with pre-3.4
1123	*broadcast = \&send;	1888	*broadcast = \&send;
1124	*wait = \&_wait;	1889	*wait = \&recv;
1125		1890
1126	package AnyEvent::Base::Strict;	1891	=head1 ERROR AND EXCEPTION HANDLING
1127		1892
1128	use Carp qw(croak);	1893	In general, AnyEvent does not do any error handling - it relies on the
		1894	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1895	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1896	checking of all AnyEvent methods, however, which is highly useful during
		1897	development.
1129		1898
1130	# supply checks for argument validity for many functions	1899	As for exception handling (i.e. runtime errors and exceptions thrown while
		1900	executing a callback), this is not only highly event-loop specific, but
		1901	also not in any way wrapped by this module, as this is the job of the main
		1902	program.
1131		1903
1132	sub io {	1904	The pure perl event loop simply re-throws the exception (usually
1133	my $class = shift;	1905	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
1134	my %arg = @_;	1906	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1907	so on.
1135		1908
1136	ref $arg{cb}	1909	=head1 ENVIRONMENT VARIABLES
1137	or croak "AnyEvent->io called with illegal cb argument '$arg{cb}'";
1138	delete $arg{cb};
1139
1140	fileno $arg{fh}
1141	or croak "AnyEvent->io called with illegal fh argument '$arg{fh}'";
1142	delete $arg{fh};
1143
1144	$arg{poll} =~ /^[rw]$/
1145	or croak "AnyEvent->io called with illegal poll argument '$arg{poll}'";
1146	delete $arg{poll};
1147
1148	croak "AnyEvent->io called with unsupported parameter(s) " . join ", ", keys %arg
1149	if keys %arg;
1150		1910
1151	$class->SUPER::io (@_)	1911	The following environment variables are used by this module or its
1152	}	1912	submodules.
1153		1913
1154	sub timer {	1914	Note that AnyEvent will remove I<all> environment variables starting with
1155	my $class = shift;	1915	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
1156	my %arg = @_;	1916	enabled.
1157		1917
1158	ref $arg{cb}	1918	=over 4
1159	or croak "AnyEvent->timer called with illegal cb argument '$arg{cb}'";
1160	delete $arg{cb};
1161
1162	exists $arg{after}
1163	or croak "AnyEvent->timer called without mandatory 'after' parameter";
1164	delete $arg{after};
1165
1166	$arg{interval} > 0 || !$arg{interval}
1167	or croak "AnyEvent->timer called with illegal interval argument '$arg{interval}'";
1168	delete $arg{interval};
1169
1170	croak "AnyEvent->timer called with unsupported parameter(s) " . join ", ", keys %arg
1171	if keys %arg;
1172		1919
1173	$class->SUPER::timer (@_)	1920	=item C<PERL_ANYEVENT_VERBOSE>
1174	}
1175		1921
1176	sub signal {	1922	By default, AnyEvent will be completely silent except in fatal
1177	my $class = shift;	1923	conditions. You can set this environment variable to make AnyEvent more
1178	my %arg = @_;	1924	talkative.
1179		1925
1180	ref $arg{cb}	1926	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1181	or croak "AnyEvent->signal called with illegal cb argument '$arg{cb}'";	1927	conditions, such as not being able to load the event model specified by
1182	delete $arg{cb};	1928	C<PERL_ANYEVENT_MODEL>.
1183
1184	eval "require POSIX; defined &POSIX::SIG$arg{signal}"
1185	or croak "AnyEvent->signal called with illegal signal name '$arg{signal}'";
1186	delete $arg{signal};
1187
1188	croak "AnyEvent->signal called with unsupported parameter(s) " . join ", ", keys %arg
1189	if keys %arg;
1190		1929
1191	$class->SUPER::signal (@_)	1930	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1192	}	1931	model it chooses.
1193		1932
1194	sub child {	1933	When set to C<8> or higher, then AnyEvent will report extra information on
1195	my $class = shift;	1934	which optional modules it loads and how it implements certain features.
1196	my %arg = @_;
1197		1935
1198	ref $arg{cb}	1936	=item C<PERL_ANYEVENT_STRICT>
1199	or croak "AnyEvent->signal called with illegal cb argument '$arg{cb}'";
1200	delete $arg{cb};
1201
1202	$arg{pid} =~ /^-?\d+$/
1203	or croak "AnyEvent->signal called with illegal pid value '$arg{pid}'";
1204	delete $arg{pid};
1205
1206	croak "AnyEvent->signal called with unsupported parameter(s) " . join ", ", keys %arg
1207	if keys %arg;
1208		1937
1209	$class->SUPER::child (@_)	1938	AnyEvent does not do much argument checking by default, as thorough
1210	}	1939	argument checking is very costly. Setting this variable to a true value
		1940	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1941	check the arguments passed to most method calls. If it finds any problems,
		1942	it will croak.
1211		1943
1212	sub condvar {	1944	In other words, enables "strict" mode.
1213	my $class = shift;
1214	my %arg = @_;
1215		1945
1216	!exists $arg{cb} or ref $arg{cb}	1946	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1217	or croak "AnyEvent->condvar called with illegal cb argument '$arg{cb}'";	1947	>>, it is definitely recommended to keep it off in production. Keeping
1218	delete $arg{cb};	1948	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1219		1949	can be very useful, however.
1220	croak "AnyEvent->condvar called with unsupported parameter(s) " . join ", ", keys %arg
1221	if keys %arg;
1222		1950
1223	$class->SUPER::condvar (@_)	1951	=item C<PERL_ANYEVENT_MODEL>
1224	}
1225		1952
1226	sub time {	1953	This can be used to specify the event model to be used by AnyEvent, before
1227	my $class = shift;	1954	auto detection and -probing kicks in.
1228		1955
1229	@_	1956	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
1230	and croak "AnyEvent->time wrongly called with paramaters";	1957	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		1958	resulting module name is loaded and - if the load was successful - used as
		1959	event model backend. If it fails to load then AnyEvent will proceed with
		1960	auto detection and -probing.
1231		1961
1232	$class->SUPER::time (@_)	1962	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
1233	}	1963	nothing gets prepended and the module name is used as-is (hint: C<::> at
		1964	the end of a string designates a module name and quotes it appropriately).
1234		1965
1235	sub now {	1966	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1236	my $class = shift;	1967	could start your program like this:
1237		1968
1238	@_	1969	PERL_ANYEVENT_MODEL=Perl perl ...
1239	and croak "AnyEvent->now wrongly called with paramaters";
1240		1970
1241	$class->SUPER::now (@_)	1971	=item C<PERL_ANYEVENT_PROTOCOLS>
1242	}	1972
		1973	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1974	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1975	of auto probing).
		1976
		1977	Must be set to a comma-separated list of protocols or address families,
		1978	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1979	used, and preference will be given to protocols mentioned earlier in the
		1980	list.
		1981
		1982	This variable can effectively be used for denial-of-service attacks
		1983	against local programs (e.g. when setuid), although the impact is likely
		1984	small, as the program has to handle conenction and other failures anyways.
		1985
		1986	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1987	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1988	- only support IPv4, never try to resolve or contact IPv6
		1989	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1990	IPv6, but prefer IPv6 over IPv4.
		1991
		1992	=item C<PERL_ANYEVENT_EDNS0>
		1993
		1994	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1995	for DNS. This extension is generally useful to reduce DNS traffic, but
		1996	some (broken) firewalls drop such DNS packets, which is why it is off by
		1997	default.
		1998
		1999	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2000	EDNS0 in its DNS requests.
		2001
		2002	=item C<PERL_ANYEVENT_MAX_FORKS>
		2003
		2004	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2005	will create in parallel.
		2006
		2007	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2008
		2009	The default value for the C<max_outstanding> parameter for the default DNS
		2010	resolver - this is the maximum number of parallel DNS requests that are
		2011	sent to the DNS server.
		2012
		2013	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2014
		2015	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2016	configuration) in the default resolver. When set to the empty string, no
		2017	default config will be used.
		2018
		2019	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2020
		2021	When neither C<ca_file> nor C<ca_path> was specified during
		2022	L<AnyEvent::TLS> context creation, and either of these environment
		2023	variables exist, they will be used to specify CA certificate locations
		2024	instead of a system-dependent default.
		2025
		2026	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2027
		2028	When these are set to C<1>, then the respective modules are not
		2029	loaded. Mostly good for testing AnyEvent itself.
		2030
		2031	=back
1243		2032
1244	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2033	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1245		2034
1246	This is an advanced topic that you do not normally need to use AnyEvent in	2035	This is an advanced topic that you do not normally need to use AnyEvent in
1247	a module. This section is only of use to event loop authors who want to	2036	a module. This section is only of use to event loop authors who want to
…		…
1281		2070
1282	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2071	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1283	condition variables: code blocking while waiting for a condition will	2072	condition variables: code blocking while waiting for a condition will
1284	C<die>. This still works with most modules/usages, and blocking calls must	2073	C<die>. This still works with most modules/usages, and blocking calls must
1285	not be done in an interactive application, so it makes sense.	2074	not be done in an interactive application, so it makes sense.
1286
1287	=head1 ENVIRONMENT VARIABLES
1288
1289	The following environment variables are used by this module:
1290
1291	=over 4
1292
1293	=item C<PERL_ANYEVENT_VERBOSE>
1294
1295	By default, AnyEvent will be completely silent except in fatal
1296	conditions. You can set this environment variable to make AnyEvent more
1297	talkative.
1298
1299	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1300	conditions, such as not being able to load the event model specified by
1301	C<PERL_ANYEVENT_MODEL>.
1302
1303	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1304	model it chooses.
1305
1306	=item C<PERL_ANYEVENT_STRICT>
1307
1308	AnyEvent does not do much argument checking by default, as thorough
1309	argument checking is very costly. Setting this variable to a true value
1310	will cause AnyEvent to thoroughly check the arguments passed to most
1311	method calls and croaks if it finds any problems. In other words, enables
1312	"strict" mode. Unlike C<use strict> it is definitely recommended ot keep
1313	it off in production.
1314
1315	=item C<PERL_ANYEVENT_MODEL>
1316
1317	This can be used to specify the event model to be used by AnyEvent, before
1318	auto detection and -probing kicks in. It must be a string consisting
1319	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1320	and the resulting module name is loaded and if the load was successful,
1321	used as event model. If it fails to load AnyEvent will proceed with
1322	auto detection and -probing.
1323
1324	This functionality might change in future versions.
1325
1326	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1327	could start your program like this:
1328
1329	PERL_ANYEVENT_MODEL=Perl perl ...
1330
1331	=item C<PERL_ANYEVENT_PROTOCOLS>
1332
1333	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1334	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1335	of auto probing).
1336
1337	Must be set to a comma-separated list of protocols or address families,
1338	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1339	used, and preference will be given to protocols mentioned earlier in the
1340	list.
1341
1342	This variable can effectively be used for denial-of-service attacks
1343	against local programs (e.g. when setuid), although the impact is likely
1344	small, as the program has to handle connection errors already-
1345
1346	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1347	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1348	- only support IPv4, never try to resolve or contact IPv6
1349	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1350	IPv6, but prefer IPv6 over IPv4.
1351
1352	=item C<PERL_ANYEVENT_EDNS0>
1353
1354	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1355	for DNS. This extension is generally useful to reduce DNS traffic, but
1356	some (broken) firewalls drop such DNS packets, which is why it is off by
1357	default.
1358
1359	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1360	EDNS0 in its DNS requests.
1361
1362	=item C<PERL_ANYEVENT_MAX_FORKS>
1363
1364	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1365	will create in parallel.
1366
1367	=back
1368		2075
1369	=head1 EXAMPLE PROGRAM	2076	=head1 EXAMPLE PROGRAM
1370		2077
1371	The following program uses an I/O watcher to read data from STDIN, a timer	2078	The following program uses an I/O watcher to read data from STDIN, a timer
1372	to display a message once per second, and a condition variable to quit the	2079	to display a message once per second, and a condition variable to quit the
…		…
1385	warn "read: $input\n"; # output what has been read	2092	warn "read: $input\n"; # output what has been read
1386	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2093	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1387	},	2094	},
1388	);	2095	);
1389		2096
1390	my $time_watcher; # can only be used once
1391
1392	sub new_timer {
1393	$timer = AnyEvent->timer (after => 1, cb => sub {	2097	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1394	warn "timeout\n"; # print 'timeout' about every second	2098	warn "timeout\n"; # print 'timeout' at most every second
1395	&new_timer; # and restart the time
1396	});	2099	});
1397	}
1398
1399	new_timer; # create first timer
1400		2100
1401	$cv->recv; # wait until user enters /^q/i	2101	$cv->recv; # wait until user enters /^q/i
1402		2102
1403	=head1 REAL-WORLD EXAMPLE	2103	=head1 REAL-WORLD EXAMPLE
1404		2104
…		…
1477		2177
1478	The actual code goes further and collects all errors (C<die>s, exceptions)	2178	The actual code goes further and collects all errors (C<die>s, exceptions)
1479	that occurred during request processing. The C<result> method detects	2179	that occurred during request processing. The C<result> method detects
1480	whether an exception as thrown (it is stored inside the $txn object)	2180	whether an exception as thrown (it is stored inside the $txn object)
1481	and just throws the exception, which means connection errors and other	2181	and just throws the exception, which means connection errors and other
1482	problems get reported tot he code that tries to use the result, not in a	2182	problems get reported to the code that tries to use the result, not in a
1483	random callback.	2183	random callback.
1484		2184
1485	All of this enables the following usage styles:	2185	All of this enables the following usage styles:
1486		2186
1487	1. Blocking:	2187	1. Blocking:
…		…
1535	through AnyEvent. The benchmark creates a lot of timers (with a zero	2235	through AnyEvent. The benchmark creates a lot of timers (with a zero
1536	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2236	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1537	which it is), lets them fire exactly once and destroys them again.	2237	which it is), lets them fire exactly once and destroys them again.
1538		2238
1539	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2239	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1540	distribution.	2240	distribution. It uses the L<AE> interface, which makes a real difference
		2241	for the EV and Perl backends only.
1541		2242
1542	=head3 Explanation of the columns	2243	=head3 Explanation of the columns
1543		2244
1544	I<watcher> is the number of event watchers created/destroyed. Since	2245	I<watcher> is the number of event watchers created/destroyed. Since
1545	different event models feature vastly different performances, each event	2246	different event models feature vastly different performances, each event
…		…
1566	watcher.	2267	watcher.
1567		2268
1568	=head3 Results	2269	=head3 Results
1569		2270
1570	name watchers bytes create invoke destroy comment	2271	name watchers bytes create invoke destroy comment
1571	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2272	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1572	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2273	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1573	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2274	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1574	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2275	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1575	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2276	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1576	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2277	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2278	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2279	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1577	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2280	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1578	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2281	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1579	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2282	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1580	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2283	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1581		2284
1582	=head3 Discussion	2285	=head3 Discussion
1583		2286
1584	The benchmark does I<not> measure scalability of the event loop very	2287	The benchmark does I<not> measure scalability of the event loop very
1585	well. For example, a select-based event loop (such as the pure perl one)	2288	well. For example, a select-based event loop (such as the pure perl one)
…		…
1597	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2300	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1598	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2301	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1599	cycles with POE.	2302	cycles with POE.
1600		2303
1601	C<EV> is the sole leader regarding speed and memory use, which are both	2304	C<EV> is the sole leader regarding speed and memory use, which are both
1602	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2305	maximal/minimal, respectively. When using the L<AE> API there is zero
		2306	overhead (when going through the AnyEvent API create is about 5-6 times
		2307	slower, with other times being equal, so still uses far less memory than
1603	far less memory than any other event loop and is still faster than Event	2308	any other event loop and is still faster than Event natively).
1604	natively.
1605		2309
1606	The pure perl implementation is hit in a few sweet spots (both the	2310	The pure perl implementation is hit in a few sweet spots (both the
1607	constant timeout and the use of a single fd hit optimisations in the perl	2311	constant timeout and the use of a single fd hit optimisations in the perl
1608	interpreter and the backend itself). Nevertheless this shows that it	2312	interpreter and the backend itself). Nevertheless this shows that it
1609	adds very little overhead in itself. Like any select-based backend its	2313	adds very little overhead in itself. Like any select-based backend its
1610	performance becomes really bad with lots of file descriptors (and few of	2314	performance becomes really bad with lots of file descriptors (and few of
1611	them active), of course, but this was not subject of this benchmark.	2315	them active), of course, but this was not subject of this benchmark.
1612		2316
1613	The C<Event> module has a relatively high setup and callback invocation	2317	The C<Event> module has a relatively high setup and callback invocation
1614	cost, but overall scores in on the third place.	2318	cost, but overall scores in on the third place.
		2319
		2320	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2321	when using its pure perl backend.
1615		2322
1616	C<Glib>'s memory usage is quite a bit higher, but it features a	2323	C<Glib>'s memory usage is quite a bit higher, but it features a
1617	faster callback invocation and overall ends up in the same class as	2324	faster callback invocation and overall ends up in the same class as
1618	C<Event>. However, Glib scales extremely badly, doubling the number of	2325	C<Event>. However, Glib scales extremely badly, doubling the number of
1619	watchers increases the processing time by more than a factor of four,	2326	watchers increases the processing time by more than a factor of four,
…		…
1680	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2387	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1681	(1%) are active. This mirrors the activity of large servers with many	2388	(1%) are active. This mirrors the activity of large servers with many
1682	connections, most of which are idle at any one point in time.	2389	connections, most of which are idle at any one point in time.
1683		2390
1684	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2391	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1685	distribution.	2392	distribution. It uses the L<AE> interface, which makes a real difference
		2393	for the EV and Perl backends only.
1686		2394
1687	=head3 Explanation of the columns	2395	=head3 Explanation of the columns
1688		2396
1689	I<sockets> is the number of sockets, and twice the number of "servers" (as	2397	I<sockets> is the number of sockets, and twice the number of "servers" (as
1690	each server has a read and write socket end).	2398	each server has a read and write socket end).
…		…
1697	it to another server. This includes deleting the old timeout and creating	2405	it to another server. This includes deleting the old timeout and creating
1698	a new one that moves the timeout into the future.	2406	a new one that moves the timeout into the future.
1699		2407
1700	=head3 Results	2408	=head3 Results
1701		2409
1702	name sockets create request	2410	name sockets create request
1703	EV 20000 69.01 11.16	2411	EV 20000 62.66 7.99
1704	Perl 20000 73.32 35.87	2412	Perl 20000 68.32 32.64
1705	Event 20000 212.62 257.32	2413	IOAsync 20000 174.06 101.15 epoll
1706	Glib 20000 651.16 1896.30	2414	IOAsync 20000 174.67 610.84 poll
		2415	Event 20000 202.69 242.91
		2416	Glib 20000 557.01 1689.52
1707	POE 20000 349.67 12317.24 uses POE::Loop::Event	2417	POE 20000 341.54 12086.32 uses POE::Loop::Event
1708		2418
1709	=head3 Discussion	2419	=head3 Discussion
1710		2420
1711	This benchmark I<does> measure scalability and overall performance of the	2421	This benchmark I<does> measure scalability and overall performance of the
1712	particular event loop.	2422	particular event loop.
…		…
1714	EV is again fastest. Since it is using epoll on my system, the setup time	2424	EV is again fastest. Since it is using epoll on my system, the setup time
1715	is relatively high, though.	2425	is relatively high, though.
1716		2426
1717	Perl surprisingly comes second. It is much faster than the C-based event	2427	Perl surprisingly comes second. It is much faster than the C-based event
1718	loops Event and Glib.	2428	loops Event and Glib.
		2429
		2430	IO::Async performs very well when using its epoll backend, and still quite
		2431	good compared to Glib when using its pure perl backend.
1719		2432
1720	Event suffers from high setup time as well (look at its code and you will	2433	Event suffers from high setup time as well (look at its code and you will
1721	understand why). Callback invocation also has a high overhead compared to	2434	understand why). Callback invocation also has a high overhead compared to
1722	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2435	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1723	uses select or poll in basically all documented configurations.	2436	uses select or poll in basically all documented configurations.
…		…
1786	=item * C-based event loops perform very well with small number of	2499	=item * C-based event loops perform very well with small number of
1787	watchers, as the management overhead dominates.	2500	watchers, as the management overhead dominates.
1788		2501
1789	=back	2502	=back
1790		2503
		2504	=head2 THE IO::Lambda BENCHMARK
		2505
		2506	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2507	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2508	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2509	shouldn't come as a surprise to anybody). As such, the benchmark is
		2510	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2511	very optimal. But how would AnyEvent compare when used without the extra
		2512	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2513
		2514	The benchmark itself creates an echo-server, and then, for 500 times,
		2515	connects to the echo server, sends a line, waits for the reply, and then
		2516	creates the next connection. This is a rather bad benchmark, as it doesn't
		2517	test the efficiency of the framework or much non-blocking I/O, but it is a
		2518	benchmark nevertheless.
		2519
		2520	name runtime
		2521	Lambda/select 0.330 sec
		2522	+ optimized 0.122 sec
		2523	Lambda/AnyEvent 0.327 sec
		2524	+ optimized 0.138 sec
		2525	Raw sockets/select 0.077 sec
		2526	POE/select, components 0.662 sec
		2527	POE/select, raw sockets 0.226 sec
		2528	POE/select, optimized 0.404 sec
		2529
		2530	AnyEvent/select/nb 0.085 sec
		2531	AnyEvent/EV/nb 0.068 sec
		2532	+state machine 0.134 sec
		2533
		2534	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2535	benchmarks actually make blocking connects and use 100% blocking I/O,
		2536	defeating the purpose of an event-based solution. All of the newly
		2537	written AnyEvent benchmarks use 100% non-blocking connects (using
		2538	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2539	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2540	generally require a lot more bookkeeping and event handling than blocking
		2541	connects (which involve a single syscall only).
		2542
		2543	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2544	offers similar expressive power as POE and IO::Lambda, using conventional
		2545	Perl syntax. This means that both the echo server and the client are 100%
		2546	non-blocking, further placing it at a disadvantage.
		2547
		2548	As you can see, the AnyEvent + EV combination even beats the
		2549	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2550	backend easily beats IO::Lambda and POE.
		2551
		2552	And even the 100% non-blocking version written using the high-level (and
		2553	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2554	higher level ("unoptimised") abstractions by a large margin, even though
		2555	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2556
		2557	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2558	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2559	part of the IO::Lambda distribution and were used without any changes.
		2560
		2561
		2562	=head1 SIGNALS
		2563
		2564	AnyEvent currently installs handlers for these signals:
		2565
		2566	=over 4
		2567
		2568	=item SIGCHLD
		2569
		2570	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2571	emulation for event loops that do not support them natively. Also, some
		2572	event loops install a similar handler.
		2573
		2574	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2575	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2576
		2577	=item SIGPIPE
		2578
		2579	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2580	when AnyEvent gets loaded.
		2581
		2582	The rationale for this is that AnyEvent users usually do not really depend
		2583	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2584	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2585	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2586	some random socket.
		2587
		2588	The rationale for installing a no-op handler as opposed to ignoring it is
		2589	that this way, the handler will be restored to defaults on exec.
		2590
		2591	Feel free to install your own handler, or reset it to defaults.
		2592
		2593	=back
		2594
		2595	=cut
		2596
		2597	undef $SIG{CHLD}
		2598	if $SIG{CHLD} eq 'IGNORE';
		2599
		2600	$SIG{PIPE} = sub { }
		2601	unless defined $SIG{PIPE};
		2602
		2603	=head1 RECOMMENDED/OPTIONAL MODULES
		2604
		2605	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2606	its built-in modules) are required to use it.
		2607
		2608	That does not mean that AnyEvent won't take advantage of some additional
		2609	modules if they are installed.
		2610
		2611	This section explains which additional modules will be used, and how they
		2612	affect AnyEvent's operation.
		2613
		2614	=over 4
		2615
		2616	=item L<Async::Interrupt>
		2617
		2618	This slightly arcane module is used to implement fast signal handling: To
		2619	my knowledge, there is no way to do completely race-free and quick
		2620	signal handling in pure perl. To ensure that signals still get
		2621	delivered, AnyEvent will start an interval timer to wake up perl (and
		2622	catch the signals) with some delay (default is 10 seconds, look for
		2623	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2624
		2625	If this module is available, then it will be used to implement signal
		2626	catching, which means that signals will not be delayed, and the event loop
		2627	will not be interrupted regularly, which is more efficient (and good for
		2628	battery life on laptops).
		2629
		2630	This affects not just the pure-perl event loop, but also other event loops
		2631	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2632
		2633	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2634	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2635	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2636	does nothing for those backends.
		2637
		2638	=item L<EV>
		2639
		2640	This module isn't really "optional", as it is simply one of the backend
		2641	event loops that AnyEvent can use. However, it is simply the best event
		2642	loop available in terms of features, speed and stability: It supports
		2643	the AnyEvent API optimally, implements all the watcher types in XS, does
		2644	automatic timer adjustments even when no monotonic clock is available,
		2645	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2646	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2647	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2648
		2649	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2650	then this module will do nothing for you.
		2651
		2652	=item L<Guard>
		2653
		2654	The guard module, when used, will be used to implement
		2655	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2656	lot less memory), but otherwise doesn't affect guard operation much. It is
		2657	purely used for performance.
		2658
		2659	=item L<JSON> and L<JSON::XS>
		2660
		2661	One of these modules is required when you want to read or write JSON data
		2662	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2663	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2664
		2665	=item L<Net::SSLeay>
		2666
		2667	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2668	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2669	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2670
		2671	=item L<Time::HiRes>
		2672
		2673	This module is part of perl since release 5.008. It will be used when the
		2674	chosen event library does not come with a timing source of its own. The
		2675	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2676	try to use a monotonic clock for timing stability.
		2677
		2678	=back
		2679
1791		2680
1792	=head1 FORK	2681	=head1 FORK
1793		2682
1794	Most event libraries are not fork-safe. The ones who are usually are	2683	Most event libraries are not fork-safe. The ones who are usually are
1795	because they rely on inefficient but fork-safe C<select> or C<poll>	2684	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1796	calls. Only L<EV> is fully fork-aware.	2685	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2686	are usually badly thought-out hacks that are incompatible with fork in
		2687	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2688	continue event-processing in both parent and child (or both, if you know
		2689	what you are doing).
		2690
		2691	This means that, in general, you cannot fork and do event processing in
		2692	the child if the event library was initialised before the fork (which
		2693	usually happens when the first AnyEvent watcher is created, or the library
		2694	is loaded).
1797		2695
1798	If you have to fork, you must either do so I<before> creating your first	2696	If you have to fork, you must either do so I<before> creating your first
1799	watcher OR you must not use AnyEvent at all in the child.	2697	watcher OR you must not use AnyEvent at all in the child OR you must do
		2698	something completely out of the scope of AnyEvent.
		2699
		2700	The problem of doing event processing in the parent I<and> the child
		2701	is much more complicated: even for backends that I<are> fork-aware or
		2702	fork-safe, their behaviour is not usually what you want: fork clones all
		2703	watchers, that means all timers, I/O watchers etc. are active in both
		2704	parent and child, which is almost never what you want. USing C<exec>
		2705	to start worker children from some kind of manage rprocess is usually
		2706	preferred, because it is much easier and cleaner, at the expense of having
		2707	to have another binary.
1800		2708
1801		2709
1802	=head1 SECURITY CONSIDERATIONS	2710	=head1 SECURITY CONSIDERATIONS
1803		2711
1804	AnyEvent can be forced to load any event model via	2712	AnyEvent can be forced to load any event model via
…		…
1816	use AnyEvent;	2724	use AnyEvent;
1817		2725
1818	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2726	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1819	be used to probe what backend is used and gain other information (which is	2727	be used to probe what backend is used and gain other information (which is
1820	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2728	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1821	$ENV{PERL_ANYEGENT_STRICT}.	2729	$ENV{PERL_ANYEVENT_STRICT}.
		2730
		2731	Note that AnyEvent will remove I<all> environment variables starting with
		2732	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2733	enabled.
1822		2734
1823		2735
1824	=head1 BUGS	2736	=head1 BUGS
1825		2737
1826	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2738	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1827	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2739	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1828	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2740	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1829	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2741	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1830	pronounced).	2742	pronounced).
1831		2743
1832		2744
1833	=head1 SEE ALSO	2745	=head1 SEE ALSO
1834		2746
		2747	Tutorial/Introduction: L<AnyEvent::Intro>.
		2748
		2749	FAQ: L<AnyEvent::FAQ>.
		2750
1835	Utility functions: L<AnyEvent::Util>.	2751	Utility functions: L<AnyEvent::Util>.
1836		2752
1837	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2753	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
1838	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2754	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1839		2755
1840	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2756	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1841	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2757	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1842	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2758	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1843	L<AnyEvent::Impl::POE>.	2759	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1844		2760
1845	Non-blocking file handles, sockets, TCP clients and	2761	Non-blocking file handles, sockets, TCP clients and
1846	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2762	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1847		2763
1848	Asynchronous DNS: L<AnyEvent::DNS>.	2764	Asynchronous DNS: L<AnyEvent::DNS>.
1849		2765
1850	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2766	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1851		2767
1852	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2768	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2769	L<AnyEvent::HTTP>.
1853		2770
1854		2771
1855	=head1 AUTHOR	2772	=head1 AUTHOR
1856		2773
1857	Marc Lehmann <schmorp@schmorp.de>	2774	Marc Lehmann <schmorp@schmorp.de>

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