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Revision 1.98 by root, Sun Apr 27 16:31:48 2008 UTC vs.
Revision 1.322 by root, Sat May 8 07:51:39 2010 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Coro::EV, Coro::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
		38	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	39	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
		42
		43	=head1 INTRODUCTION/TUTORIAL
		44
		45	This manpage is mainly a reference manual. If you are interested
		46	in a tutorial or some gentle introduction, have a look at the
		47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	There is a mailinglist for discussing all things AnyEvent, and an IRC
		52	channel, too.
		53
		54	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		55	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		56
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	57	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		58
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	59	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	60	nowadays. So what is different about AnyEvent?
27		61
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	62	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	63	policy> and AnyEvent is I<small and efficient>.
30		64
31	First and foremost, I<AnyEvent is not an event model> itself, it only	65	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	66	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	67	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	68	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	69	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	70	cannot change this, but it can hide the differences between those event
		71	loops.
37		72
38	The goal of AnyEvent is to offer module authors the ability to do event	73	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	74	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	75	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	76	module users into the same thing by forcing them to use the same event
42	model you use.	77	model you use.
43		78
44	For modules like POE or IO::Async (which is a total misnomer as it is	79	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	80	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	81	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	82	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	83	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	84	module are I<also> forced to use the same event loop you use.
50		85
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	87	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	88	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	89	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	90	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	91	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	92	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	93	to AnyEvent, too, so it is future-proof).
59		94
60	In addition to being free of having to use I<the one and only true event	95	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	96	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	97	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	98	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	99	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	100	technically possible.
66		101
		102	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		103	of useful functionality, such as an asynchronous DNS resolver, 100%
		104	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		105	such as Windows) and lots of real-world knowledge and workarounds for
		106	platform bugs and differences.
		107
67	Of course, if you want lots of policy (this can arguably be somewhat	108	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	109	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	110	model, you should I<not> use this module.
70
71	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		111
91	=head1 DESCRIPTION	112	=head1 DESCRIPTION
92		113
93	L<AnyEvent> provides an identical interface to multiple event loops. This	114	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	115	allows module authors to utilise an event loop without forcing module
…		…
98	The interface itself is vaguely similar, but not identical to the L<Event>	119	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	120	module.
100		121
101	During the first call of any watcher-creation method, the module tries	122	During the first call of any watcher-creation method, the module tries
102	to detect the currently loaded event loop by probing whether one of the	123	to detect the currently loaded event loop by probing whether one of the
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	124	following modules is already loaded: L<EV>,
104	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	125	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
105	L<POE>. The first one found is used. If none are found, the module tries	126	L<POE>. The first one found is used. If none are found, the module tries
106	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	127	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
107	adaptor should always succeed) in the order given. The first one that can	128	adaptor should always succeed) in the order given. The first one that can
108	be successfully loaded will be used. If, after this, still none could be	129	be successfully loaded will be used. If, after this, still none could be
…		…
122	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off. Maybe you should tell their authors to
123	use AnyEvent so their modules work together with others seamlessly...	144	use AnyEvent so their modules work together with others seamlessly...
124		145
125	The pure-perl implementation of AnyEvent is called	146	The pure-perl implementation of AnyEvent is called
126	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	147	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
127	explicitly.	148	explicitly and enjoy the high availability of that event loop :)
128		149
129	=head1 WATCHERS	150	=head1 WATCHERS
130		151
131	AnyEvent has the central concept of a I<watcher>, which is an object that	152	AnyEvent has the central concept of a I<watcher>, which is an object that
132	stores relevant data for each kind of event you are waiting for, such as	153	stores relevant data for each kind of event you are waiting for, such as
133	the callback to call, the filehandle to watch, etc.	154	the callback to call, the file handle to watch, etc.
134		155
135	These watchers are normal Perl objects with normal Perl lifetime. After	156	These watchers are normal Perl objects with normal Perl lifetime. After
136	creating a watcher it will immediately "watch" for events and invoke the	157	creating a watcher it will immediately "watch" for events and invoke the
137	callback when the event occurs (of course, only when the event model	158	callback when the event occurs (of course, only when the event model
138	is in control).	159	is in control).
139		160
		161	Note that B<callbacks must not permanently change global variables>
		162	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		163	callbacks must not C<die> >>. The former is good programming practise in
		164	Perl and the latter stems from the fact that exception handling differs
		165	widely between event loops.
		166
140	To disable the watcher you have to destroy it (e.g. by setting the	167	To disable the watcher you have to destroy it (e.g. by setting the
141	variable you store it in to C<undef> or otherwise deleting all references	168	variable you store it in to C<undef> or otherwise deleting all references
142	to it).	169	to it).
143		170
144	All watchers are created by calling a method on the C<AnyEvent> class.	171	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
146	Many watchers either are used with "recursion" (repeating timers for	173	Many watchers either are used with "recursion" (repeating timers for
147	example), or need to refer to their watcher object in other ways.	174	example), or need to refer to their watcher object in other ways.
148		175
149	An any way to achieve that is this pattern:	176	An any way to achieve that is this pattern:
150		177
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	178	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	179	# you can use $w here, for example to undef it
153	undef $w;	180	undef $w;
154	});	181	});
155		182
156	Note that C<my $w; $w => combination. This is necessary because in Perl,	183	Note that C<my $w; $w => combination. This is necessary because in Perl,
157	my variables are only visible after the statement in which they are	184	my variables are only visible after the statement in which they are
158	declared.	185	declared.
159		186
160	=head2 I/O WATCHERS	187	=head2 I/O WATCHERS
161		188
		189	$w = AnyEvent->io (
		190	fh => <filehandle_or_fileno>,
		191	poll => <"r" or "w">,
		192	cb => <callback>,
		193	);
		194
162	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	195	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
163	with the following mandatory key-value pairs as arguments:	196	with the following mandatory key-value pairs as arguments:
164		197
165	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	198	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		199	for events (AnyEvent might or might not keep a reference to this file
		200	handle). Note that only file handles pointing to things for which
		201	non-blocking operation makes sense are allowed. This includes sockets,
		202	most character devices, pipes, fifos and so on, but not for example files
		203	or block devices.
		204
166	for events. C<poll> must be a string that is either C<r> or C<w>,	205	C<poll> must be a string that is either C<r> or C<w>, which creates a
167	which creates a watcher waiting for "r"eadable or "w"ritable events,	206	watcher waiting for "r"eadable or "w"ritable events, respectively.
		207
168	respectively. C<cb> is the callback to invoke each time the file handle	208	C<cb> is the callback to invoke each time the file handle becomes ready.
169	becomes ready.
170		209
171	Although the callback might get passed parameters, their value and	210	Although the callback might get passed parameters, their value and
172	presence is undefined and you cannot rely on them. Portable AnyEvent	211	presence is undefined and you cannot rely on them. Portable AnyEvent
173	callbacks cannot use arguments passed to I/O watcher callbacks.	212	callbacks cannot use arguments passed to I/O watcher callbacks.
174		213
…		…
178		217
179	Some event loops issue spurious readyness notifications, so you should	218	Some event loops issue spurious readyness notifications, so you should
180	always use non-blocking calls when reading/writing from/to your file	219	always use non-blocking calls when reading/writing from/to your file
181	handles.	220	handles.
182		221
183	Example:
184
185	# wait for readability of STDIN, then read a line and disable the watcher	222	Example: wait for readability of STDIN, then read a line and disable the
		223	watcher.
		224
186	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	225	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
187	chomp (my $input = <STDIN>);	226	chomp (my $input = <STDIN>);
188	warn "read: $input\n";	227	warn "read: $input\n";
189	undef $w;	228	undef $w;
190	});	229	});
191		230
192	=head2 TIME WATCHERS	231	=head2 TIME WATCHERS
193		232
		233	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		234
		235	$w = AnyEvent->timer (
		236	after => <fractional_seconds>,
		237	interval => <fractional_seconds>,
		238	cb => <callback>,
		239	);
		240
194	You can create a time watcher by calling the C<< AnyEvent->timer >>	241	You can create a time watcher by calling the C<< AnyEvent->timer >>
195	method with the following mandatory arguments:	242	method with the following mandatory arguments:
196		243
197	C<after> specifies after how many seconds (fractional values are	244	C<after> specifies after how many seconds (fractional values are
198	supported) the callback should be invoked. C<cb> is the callback to invoke	245	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
200		247
201	Although the callback might get passed parameters, their value and	248	Although the callback might get passed parameters, their value and
202	presence is undefined and you cannot rely on them. Portable AnyEvent	249	presence is undefined and you cannot rely on them. Portable AnyEvent
203	callbacks cannot use arguments passed to time watcher callbacks.	250	callbacks cannot use arguments passed to time watcher callbacks.
204		251
205	The timer callback will be invoked at most once: if you want a repeating	252	The callback will normally be invoked once only. If you specify another
206	timer you have to create a new watcher (this is a limitation by both Tk	253	parameter, C<interval>, as a strictly positive number (> 0), then the
207	and Glib).	254	callback will be invoked regularly at that interval (in fractional
		255	seconds) after the first invocation. If C<interval> is specified with a
		256	false value, then it is treated as if it were missing.
208		257
209	Example:	258	The callback will be rescheduled before invoking the callback, but no
		259	attempt is done to avoid timer drift in most backends, so the interval is
		260	only approximate.
210		261
211	# fire an event after 7.7 seconds	262	Example: fire an event after 7.7 seconds.
		263
212	my $w = AnyEvent->timer (after => 7.7, cb => sub {	264	my $w = AnyEvent->timer (after => 7.7, cb => sub {
213	warn "timeout\n";	265	warn "timeout\n";
214	});	266	});
215		267
216	# to cancel the timer:	268	# to cancel the timer:
217	undef $w;	269	undef $w;
218		270
219	Example 2:
220
221	# fire an event after 0.5 seconds, then roughly every second	271	Example 2: fire an event after 0.5 seconds, then roughly every second.
222	my $w;
223		272
224	my $cb = sub {
225	# cancel the old timer while creating a new one
226	$w = AnyEvent->timer (after => 1, cb => $cb);	273	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		274	warn "timeout\n";
227	};	275	};
228
229	# start the "loop" by creating the first watcher
230	$w = AnyEvent->timer (after => 0.5, cb => $cb);
231		276
232	=head3 TIMING ISSUES	277	=head3 TIMING ISSUES
233		278
234	There are two ways to handle timers: based on real time (relative, "fire	279	There are two ways to handle timers: based on real time (relative, "fire
235	in 10 seconds") and based on wallclock time (absolute, "fire at 12	280	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
247	timers.	292	timers.
248		293
249	AnyEvent always prefers relative timers, if available, matching the	294	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	295	AnyEvent API.
251		296
		297	AnyEvent has two additional methods that return the "current time":
		298
		299	=over 4
		300
		301	=item AnyEvent->time
		302
		303	This returns the "current wallclock time" as a fractional number of
		304	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		305	return, and the result is guaranteed to be compatible with those).
		306
		307	It progresses independently of any event loop processing, i.e. each call
		308	will check the system clock, which usually gets updated frequently.
		309
		310	=item AnyEvent->now
		311
		312	This also returns the "current wallclock time", but unlike C<time>, above,
		313	this value might change only once per event loop iteration, depending on
		314	the event loop (most return the same time as C<time>, above). This is the
		315	time that AnyEvent's timers get scheduled against.
		316
		317	I<In almost all cases (in all cases if you don't care), this is the
		318	function to call when you want to know the current time.>
		319
		320	This function is also often faster then C<< AnyEvent->time >>, and
		321	thus the preferred method if you want some timestamp (for example,
		322	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		323
		324	The rest of this section is only of relevance if you try to be very exact
		325	with your timing, you can skip it without bad conscience.
		326
		327	For a practical example of when these times differ, consider L<Event::Lib>
		328	and L<EV> and the following set-up:
		329
		330	The event loop is running and has just invoked one of your callback at
		331	time=500 (assume no other callbacks delay processing). In your callback,
		332	you wait a second by executing C<sleep 1> (blocking the process for a
		333	second) and then (at time=501) you create a relative timer that fires
		334	after three seconds.
		335
		336	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		337	both return C<501>, because that is the current time, and the timer will
		338	be scheduled to fire at time=504 (C<501> + C<3>).
		339
		340	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		341	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		342	last event processing phase started. With L<EV>, your timer gets scheduled
		343	to run at time=503 (C<500> + C<3>).
		344
		345	In one sense, L<Event::Lib> is more exact, as it uses the current time
		346	regardless of any delays introduced by event processing. However, most
		347	callbacks do not expect large delays in processing, so this causes a
		348	higher drift (and a lot more system calls to get the current time).
		349
		350	In another sense, L<EV> is more exact, as your timer will be scheduled at
		351	the same time, regardless of how long event processing actually took.
		352
		353	In either case, if you care (and in most cases, you don't), then you
		354	can get whatever behaviour you want with any event loop, by taking the
		355	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		356	account.
		357
		358	=item AnyEvent->now_update
		359
		360	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		361	the current time for each loop iteration (see the discussion of L<<
		362	AnyEvent->now >>, above).
		363
		364	When a callback runs for a long time (or when the process sleeps), then
		365	this "current" time will differ substantially from the real time, which
		366	might affect timers and time-outs.
		367
		368	When this is the case, you can call this method, which will update the
		369	event loop's idea of "current time".
		370
		371	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		372	when mod_perl executes the script, then the event loop will have the wrong
		373	idea about the "current time" (being potentially far in the past, when the
		374	script ran the last time). In that case you should arrange a call to C<<
		375	AnyEvent->now_update >> each time the web server process wakes up again
		376	(e.g. at the start of your script, or in a handler).
		377
		378	Note that updating the time I<might> cause some events to be handled.
		379
		380	=back
		381
252	=head2 SIGNAL WATCHERS	382	=head2 SIGNAL WATCHERS
253		383
		384	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		385
254	You can watch for signals using a signal watcher, C<signal> is the signal	386	You can watch for signals using a signal watcher, C<signal> is the signal
255	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	387	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
256	be invoked whenever a signal occurs.	388	callback to be invoked whenever a signal occurs.
257		389
258	Although the callback might get passed parameters, their value and	390	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	391	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	392	callbacks cannot use arguments passed to signal watcher callbacks.
261		393
262	Multiple signal occurances can be clumped together into one callback	394	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	395	invocation, and callback invocation will be synchronous. Synchronous means
264	that it might take a while until the signal gets handled by the process,	396	that it might take a while until the signal gets handled by the process,
265	but it is guarenteed not to interrupt any other callbacks.	397	but it is guaranteed not to interrupt any other callbacks.
266		398
267	The main advantage of using these watchers is that you can share a signal	399	The main advantage of using these watchers is that you can share a signal
268	between multiple watchers.	400	between multiple watchers, and AnyEvent will ensure that signals will not
		401	interrupt your program at bad times.
269		402
270	This watcher might use C<%SIG>, so programs overwriting those signals	403	This watcher might use C<%SIG> (depending on the event loop used),
271	directly will likely not work correctly.	404	so programs overwriting those signals directly will likely not work
		405	correctly.
272		406
273	Example: exit on SIGINT	407	Example: exit on SIGINT
274		408
275	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	409	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
276		410
		411	=head3 Restart Behaviour
		412
		413	While restart behaviour is up to the event loop implementation, most will
		414	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		415	pure perl implementation).
		416
		417	=head3 Safe/Unsafe Signals
		418
		419	Perl signals can be either "safe" (synchronous to opcode handling) or
		420	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		421	latter might corrupt your memory.
		422
		423	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		424	i.e. they will not interrupt your running perl program but will only be
		425	called as part of the normal event handling (just like timer, I/O etc.
		426	callbacks, too).
		427
		428	=head3 Signal Races, Delays and Workarounds
		429
		430	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		431	callbacks to signals in a generic way, which is a pity, as you cannot
		432	do race-free signal handling in perl, requiring C libraries for
		433	this. AnyEvent will try to do it's best, which means in some cases,
		434	signals will be delayed. The maximum time a signal might be delayed is
		435	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		436	variable can be changed only before the first signal watcher is created,
		437	and should be left alone otherwise. This variable determines how often
		438	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		439	will cause fewer spurious wake-ups, which is better for power and CPU
		440	saving.
		441
		442	All these problems can be avoided by installing the optional
		443	L<Async::Interrupt> module, which works with most event loops. It will not
		444	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		445	(and not with L<POE> currently, as POE does it's own workaround with
		446	one-second latency). For those, you just have to suffer the delays.
		447
277	=head2 CHILD PROCESS WATCHERS	448	=head2 CHILD PROCESS WATCHERS
278		449
		450	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		451
279	You can also watch on a child process exit and catch its exit status.	452	You can also watch on a child process exit and catch its exit status.
280		453
281	The child process is specified by the C<pid> argument (if set to C<0>, it	454	The child process is specified by the C<pid> argument (one some backends,
282	watches for any child process exit). The watcher will trigger as often	455	using C<0> watches for any child process exit, on others this will
283	as status change for the child are received. This works by installing a	456	croak). The watcher will be triggered only when the child process has
284	signal handler for C<SIGCHLD>. The callback will be called with the pid	457	finished and an exit status is available, not on any trace events
285	and exit status (as returned by waitpid), so unlike other watcher types,	458	(stopped/continued).
286	you I<can> rely on child watcher callback arguments.	459
		460	The callback will be called with the pid and exit status (as returned by
		461	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		462	callback arguments.
		463
		464	This watcher type works by installing a signal handler for C<SIGCHLD>,
		465	and since it cannot be shared, nothing else should use SIGCHLD or reap
		466	random child processes (waiting for specific child processes, e.g. inside
		467	C<system>, is just fine).
287		468
288	There is a slight catch to child watchers, however: you usually start them	469	There is a slight catch to child watchers, however: you usually start them
289	I<after> the child process was created, and this means the process could	470	I<after> the child process was created, and this means the process could
290	have exited already (and no SIGCHLD will be sent anymore).	471	have exited already (and no SIGCHLD will be sent anymore).
291		472
292	Not all event models handle this correctly (POE doesn't), but even for	473	Not all event models handle this correctly (neither POE nor IO::Async do,
		474	see their AnyEvent::Impl manpages for details), but even for event models
293	event models that I<do> handle this correctly, they usually need to be	475	that I<do> handle this correctly, they usually need to be loaded before
294	loaded before the process exits (i.e. before you fork in the first place).	476	the process exits (i.e. before you fork in the first place). AnyEvent's
		477	pure perl event loop handles all cases correctly regardless of when you
		478	start the watcher.
295		479
296	This means you cannot create a child watcher as the very first thing in an	480	This means you cannot create a child watcher as the very first
297	AnyEvent program, you I<have> to create at least one watcher before you	481	thing in an AnyEvent program, you I<have> to create at least one
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	482	watcher before you C<fork> the child (alternatively, you can call
		483	C<AnyEvent::detect>).
		484
		485	As most event loops do not support waiting for child events, they will be
		486	emulated by AnyEvent in most cases, in which the latency and race problems
		487	mentioned in the description of signal watchers apply.
299		488
300	Example: fork a process and wait for it	489	Example: fork a process and wait for it
301		490
302	my $done = AnyEvent->condvar;	491	my $done = AnyEvent->condvar;
303		492
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	493	my $pid = fork or exit 5;
307		494
308	my $w = AnyEvent->child (	495	my $w = AnyEvent->child (
309	pid => $pid,	496	pid => $pid,
310	cb => sub {	497	cb => sub {
311	my ($pid, $status) = @_;	498	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	499	warn "pid $pid exited with status $status";
313	$done->broadcast;	500	$done->send;
314	},	501	},
315	);	502	);
316		503
317	# do something else, then wait for process exit	504	# do something else, then wait for process exit
318	$done->wait;	505	$done->recv;
		506
		507	=head2 IDLE WATCHERS
		508
		509	$w = AnyEvent->idle (cb => <callback>);
		510
		511	Repeatedly invoke the callback after the process becomes idle, until
		512	either the watcher is destroyed or new events have been detected.
		513
		514	Idle watchers are useful when there is a need to do something, but it
		515	is not so important (or wise) to do it instantly. The callback will be
		516	invoked only when there is "nothing better to do", which is usually
		517	defined as "all outstanding events have been handled and no new events
		518	have been detected". That means that idle watchers ideally get invoked
		519	when the event loop has just polled for new events but none have been
		520	detected. Instead of blocking to wait for more events, the idle watchers
		521	will be invoked.
		522
		523	Unfortunately, most event loops do not really support idle watchers (only
		524	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		525	will simply call the callback "from time to time".
		526
		527	Example: read lines from STDIN, but only process them when the
		528	program is otherwise idle:
		529
		530	my @lines; # read data
		531	my $idle_w;
		532	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		533	push @lines, scalar <STDIN>;
		534
		535	# start an idle watcher, if not already done
		536	$idle_w ||= AnyEvent->idle (cb => sub {
		537	# handle only one line, when there are lines left
		538	if (my $line = shift @lines) {
		539	print "handled when idle: $line";
		540	} else {
		541	# otherwise disable the idle watcher again
		542	undef $idle_w;
		543	}
		544	});
		545	});
319		546
320	=head2 CONDITION VARIABLES	547	=head2 CONDITION VARIABLES
321		548
		549	$cv = AnyEvent->condvar;
		550
		551	$cv->send (<list>);
		552	my @res = $cv->recv;
		553
		554	If you are familiar with some event loops you will know that all of them
		555	require you to run some blocking "loop", "run" or similar function that
		556	will actively watch for new events and call your callbacks.
		557
		558	AnyEvent is slightly different: it expects somebody else to run the event
		559	loop and will only block when necessary (usually when told by the user).
		560
		561	The instrument to do that is called a "condition variable", so called
		562	because they represent a condition that must become true.
		563
		564	Now is probably a good time to look at the examples further below.
		565
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	566	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	567	>> method, usually without arguments. The only argument pair allowed is
		568	C<cb>, which specifies a callback to be called when the condition variable
		569	becomes true, with the condition variable as the first argument (but not
		570	the results).
324		571
325	A condition variable waits for a condition - precisely that the C<<	572	After creation, the condition variable is "false" until it becomes "true"
326	->broadcast >> method has been called.	573	by calling the C<send> method (or calling the condition variable as if it
		574	were a callback, read about the caveats in the description for the C<<
		575	->send >> method).
327		576
328	They are very useful to signal that a condition has been fulfilled, for	577	Condition variables are similar to callbacks, except that you can
		578	optionally wait for them. They can also be called merge points - points
		579	in time where multiple outstanding events have been processed. And yet
		580	another way to call them is transactions - each condition variable can be
		581	used to represent a transaction, which finishes at some point and delivers
		582	a result. And yet some people know them as "futures" - a promise to
		583	compute/deliver something that you can wait for.
		584
		585	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	586	for example, if you write a module that does asynchronous http requests,
330	then a condition variable would be the ideal candidate to signal the	587	then a condition variable would be the ideal candidate to signal the
331	availability of results.	588	availability of results. The user can either act when the callback is
		589	called or can synchronously C<< ->recv >> for the results.
332		590
333	You can also use condition variables to block your main program until	591	You can also use them to simulate traditional event loops - for example,
334	an event occurs - for example, you could C<< ->wait >> in your main	592	you can block your main program until an event occurs - for example, you
335	program until the user clicks the Quit button in your app, which would C<<	593	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	594	button of your app, which would C<< ->send >> the "quit" event.
337		595
338	Note that condition variables recurse into the event loop - if you have	596	Note that condition variables recurse into the event loop - if you have
339	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	597	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	598	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	599	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	600	as this asks for trouble.
343		601
344	This object has two methods:	602	Condition variables are represented by hash refs in perl, and the keys
		603	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		604	easy (it is often useful to build your own transaction class on top of
		605	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		606	it's C<new> method in your own C<new> method.
		607
		608	There are two "sides" to a condition variable - the "producer side" which
		609	eventually calls C<< -> send >>, and the "consumer side", which waits
		610	for the send to occur.
		611
		612	Example: wait for a timer.
		613
		614	# condition: "wait till the timer is fired"
		615	my $timer_fired = AnyEvent->condvar;
		616
		617	# create the timer - we could wait for, say
		618	# a handle becomign ready, or even an
		619	# AnyEvent::HTTP request to finish, but
		620	# in this case, we simply use a timer:
		621	my $w = AnyEvent->timer (
		622	after => 1,
		623	cb => sub { $timer_fired->send },
		624	);
		625
		626	# this "blocks" (while handling events) till the callback
		627	# calls ->send
		628	$timer_fired->recv;
		629
		630	Example: wait for a timer, but take advantage of the fact that condition
		631	variables are also callable directly.
		632
		633	my $done = AnyEvent->condvar;
		634	my $delay = AnyEvent->timer (after => 5, cb => $done);
		635	$done->recv;
		636
		637	Example: Imagine an API that returns a condvar and doesn't support
		638	callbacks. This is how you make a synchronous call, for example from
		639	the main program:
		640
		641	use AnyEvent::CouchDB;
		642
		643	...
		644
		645	my @info = $couchdb->info->recv;
		646
		647	And this is how you would just set a callback to be called whenever the
		648	results are available:
		649
		650	$couchdb->info->cb (sub {
		651	my @info = $_[0]->recv;
		652	});
		653
		654	=head3 METHODS FOR PRODUCERS
		655
		656	These methods should only be used by the producing side, i.e. the
		657	code/module that eventually sends the signal. Note that it is also
		658	the producer side which creates the condvar in most cases, but it isn't
		659	uncommon for the consumer to create it as well.
345		660
346	=over 4	661	=over 4
347		662
		663	=item $cv->send (...)
		664
		665	Flag the condition as ready - a running C<< ->recv >> and all further
		666	calls to C<recv> will (eventually) return after this method has been
		667	called. If nobody is waiting the send will be remembered.
		668
		669	If a callback has been set on the condition variable, it is called
		670	immediately from within send.
		671
		672	Any arguments passed to the C<send> call will be returned by all
		673	future C<< ->recv >> calls.
		674
		675	Condition variables are overloaded so one can call them directly (as if
		676	they were a code reference). Calling them directly is the same as calling
		677	C<send>.
		678
		679	=item $cv->croak ($error)
		680
		681	Similar to send, but causes all call's to C<< ->recv >> to invoke
		682	C<Carp::croak> with the given error message/object/scalar.
		683
		684	This can be used to signal any errors to the condition variable
		685	user/consumer. Doing it this way instead of calling C<croak> directly
		686	delays the error detetcion, but has the overwhelmign advantage that it
		687	diagnoses the error at the place where the result is expected, and not
		688	deep in some event clalback without connection to the actual code causing
		689	the problem.
		690
		691	=item $cv->begin ([group callback])
		692
348	=item $cv->wait	693	=item $cv->end
349		694
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	695	These two methods can be used to combine many transactions/events into
		696	one. For example, a function that pings many hosts in parallel might want
		697	to use a condition variable for the whole process.
		698
		699	Every call to C<< ->begin >> will increment a counter, and every call to
		700	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		701	>>, the (last) callback passed to C<begin> will be executed, passing the
		702	condvar as first argument. That callback is I<supposed> to call C<< ->send
		703	>>, but that is not required. If no group callback was set, C<send> will
		704	be called without any arguments.
		705
		706	You can think of C<< $cv->send >> giving you an OR condition (one call
		707	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		708	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		709
		710	Let's start with a simple example: you have two I/O watchers (for example,
		711	STDOUT and STDERR for a program), and you want to wait for both streams to
		712	close before activating a condvar:
		713
		714	my $cv = AnyEvent->condvar;
		715
		716	$cv->begin; # first watcher
		717	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		718	defined sysread $fh1, my $buf, 4096
		719	or $cv->end;
		720	});
		721
		722	$cv->begin; # second watcher
		723	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		724	defined sysread $fh2, my $buf, 4096
		725	or $cv->end;
		726	});
		727
		728	$cv->recv;
		729
		730	This works because for every event source (EOF on file handle), there is
		731	one call to C<begin>, so the condvar waits for all calls to C<end> before
		732	sending.
		733
		734	The ping example mentioned above is slightly more complicated, as the
		735	there are results to be passwd back, and the number of tasks that are
		736	begung can potentially be zero:
		737
		738	my $cv = AnyEvent->condvar;
		739
		740	my %result;
		741	$cv->begin (sub { shift->send (\%result) });
		742
		743	for my $host (@list_of_hosts) {
		744	$cv->begin;
		745	ping_host_then_call_callback $host, sub {
		746	$result{$host} = ...;
		747	$cv->end;
		748	};
		749	}
		750
		751	$cv->end;
		752
		753	This code fragment supposedly pings a number of hosts and calls
		754	C<send> after results for all then have have been gathered - in any
		755	order. To achieve this, the code issues a call to C<begin> when it starts
		756	each ping request and calls C<end> when it has received some result for
		757	it. Since C<begin> and C<end> only maintain a counter, the order in which
		758	results arrive is not relevant.
		759
		760	There is an additional bracketing call to C<begin> and C<end> outside the
		761	loop, which serves two important purposes: first, it sets the callback
		762	to be called once the counter reaches C<0>, and second, it ensures that
		763	C<send> is called even when C<no> hosts are being pinged (the loop
		764	doesn't execute once).
		765
		766	This is the general pattern when you "fan out" into multiple (but
		767	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
		768	the callback and ensure C<end> is called at least once, and then, for each
		769	subrequest you start, call C<begin> and for each subrequest you finish,
		770	call C<end>.
		771
		772	=back
		773
		774	=head3 METHODS FOR CONSUMERS
		775
		776	These methods should only be used by the consuming side, i.e. the
		777	code awaits the condition.
		778
		779	=over 4
		780
		781	=item $cv->recv
		782
		783	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	784	>> methods have been called on c<$cv>, while servicing other watchers
		785	normally.
352		786
353	You can only wait once on a condition - additional calls will return	787	You can only wait once on a condition - additional calls are valid but
354	immediately.	788	will return immediately.
		789
		790	If an error condition has been set by calling C<< ->croak >>, then this
		791	function will call C<croak>.
		792
		793	In list context, all parameters passed to C<send> will be returned,
		794	in scalar context only the first one will be returned.
		795
		796	Note that doing a blocking wait in a callback is not supported by any
		797	event loop, that is, recursive invocation of a blocking C<< ->recv
		798	>> is not allowed, and the C<recv> call will C<croak> if such a
		799	condition is detected. This condition can be slightly loosened by using
		800	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		801	any thread that doesn't run the event loop itself.
355		802
356	Not all event models support a blocking wait - some die in that case	803	Not all event models support a blocking wait - some die in that case
357	(programs might want to do that to stay interactive), so I<if you are	804	(programs might want to do that to stay interactive), so I<if you are
358	using this from a module, never require a blocking wait>, but let the	805	using this from a module, never require a blocking wait>. Instead, let the
359	caller decide whether the call will block or not (for example, by coupling	806	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting	807	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,	808	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).	809	while still supporting blocking waits if the caller so desires).
363		810
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot	811	You can ensure that C<< -recv >> never blocks by setting a callback and
365	sensibly have two C<< ->wait >>'s in parallel, as that would require	812	only calling C<< ->recv >> from within that callback (or at a later
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	813	time). This will work even when the event loop does not support blocking
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	814	waits otherwise.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		815
371	=item $cv->broadcast	816	=item $bool = $cv->ready
372		817
373	Flag the condition as ready - a running C<< ->wait >> and all further	818	Returns true when the condition is "true", i.e. whether C<send> or
374	calls to C<wait> will (eventually) return after this method has been	819	C<croak> have been called.
375	called. If nobody is waiting the broadcast will be remembered..	820
		821	=item $cb = $cv->cb ($cb->($cv))
		822
		823	This is a mutator function that returns the callback set and optionally
		824	replaces it before doing so.
		825
		826	The callback will be called when the condition becomes (or already was)
		827	"true", i.e. when C<send> or C<croak> are called (or were called), with
		828	the only argument being the condition variable itself. Calling C<recv>
		829	inside the callback or at any later time is guaranteed not to block.
376		830
377	=back	831	=back
378		832
379	Example:	833	=head1 SUPPORTED EVENT LOOPS/BACKENDS
380		834
381	# wait till the result is ready	835	The available backend classes are (every class has its own manpage):
382	my $result_ready = AnyEvent->condvar;
383		836
384	# do something such as adding a timer	837	=over 4
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392		838
393	# this "blocks" (while handling events) till the watcher	839	=item Backends that are autoprobed when no other event loop can be found.
394	# calls broadcast	840
395	$result_ready->wait;	841	EV is the preferred backend when no other event loop seems to be in
		842	use. If EV is not installed, then AnyEvent will fall back to its own
		843	pure-perl implementation, which is available everywhere as it comes with
		844	AnyEvent itself.
		845
		846	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		847	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		848
		849	=item Backends that are transparently being picked up when they are used.
		850
		851	These will be used when they are currently loaded when the first watcher
		852	is created, in which case it is assumed that the application is using
		853	them. This means that AnyEvent will automatically pick the right backend
		854	when the main program loads an event module before anything starts to
		855	create watchers. Nothing special needs to be done by the main program.
		856
		857	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		858	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		859	AnyEvent::Impl::Tk based on Tk, very broken.
		860	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		861	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		862	AnyEvent::Impl::Irssi used when running within irssi.
		863
		864	=item Backends with special needs.
		865
		866	Qt requires the Qt::Application to be instantiated first, but will
		867	otherwise be picked up automatically. As long as the main program
		868	instantiates the application before any AnyEvent watchers are created,
		869	everything should just work.
		870
		871	AnyEvent::Impl::Qt based on Qt.
		872
		873	Support for IO::Async can only be partial, as it is too broken and
		874	architecturally limited to even support the AnyEvent API. It also
		875	is the only event loop that needs the loop to be set explicitly, so
		876	it can only be used by a main program knowing about AnyEvent. See
		877	L<AnyEvent::Impl::Async> for the gory details.
		878
		879	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		880
		881	=item Event loops that are indirectly supported via other backends.
		882
		883	Some event loops can be supported via other modules:
		884
		885	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		886
		887	B<WxWidgets> has no support for watching file handles. However, you can
		888	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		889	polls 20 times per second, which was considered to be too horrible to even
		890	consider for AnyEvent.
		891
		892	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		893	backend, so it can be supported through POE.
		894
		895	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		896	load L<POE> when detecting them, in the hope that POE will pick them up,
		897	in which case everything will be automatic.
		898
		899	=back
396		900
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	901	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		902
		903	These are not normally required to use AnyEvent, but can be useful to
		904	write AnyEvent extension modules.
		905
399	=over 4	906	=over 4
400		907
401	=item $AnyEvent::MODEL	908	=item $AnyEvent::MODEL
402		909
403	Contains C<undef> until the first watcher is being created. Then it	910	Contains C<undef> until the first watcher is being created, before the
		911	backend has been autodetected.
		912
404	contains the event model that is being used, which is the name of the	913	Afterwards it contains the event model that is being used, which is the
405	Perl class implementing the model. This class is usually one of the	914	name of the Perl class implementing the model. This class is usually one
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	915	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	916	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
408		917	will be C<urxvt::anyevent>).
409	The known classes so far are:
410
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421
422	There is no support for WxWidgets, as WxWidgets has no support for
423	watching file handles. However, you can use WxWidgets through the
424	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
425	second, which was considered to be too horrible to even consider for
426	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
427	it's adaptor.
428
429	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
430	autodetecting them.
431		918
432	=item AnyEvent::detect	919	=item AnyEvent::detect
433		920
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	921	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	922	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	923	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	924	runtime, and not e.g. while initialising of your module.
		925
		926	If you need to do some initialisation before AnyEvent watchers are
		927	created, use C<post_detect>.
		928
		929	=item $guard = AnyEvent::post_detect { BLOCK }
		930
		931	Arranges for the code block to be executed as soon as the event model is
		932	autodetected (or immediately if this has already happened).
		933
		934	The block will be executed I<after> the actual backend has been detected
		935	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		936	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		937	other initialisations - see the sources of L<AnyEvent::Strict> or
		938	L<AnyEvent::AIO> to see how this is used.
		939
		940	The most common usage is to create some global watchers, without forcing
		941	event module detection too early, for example, L<AnyEvent::AIO> creates
		942	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		943	avoid autodetecting the event module at load time.
		944
		945	If called in scalar or list context, then it creates and returns an object
		946	that automatically removes the callback again when it is destroyed (or
		947	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
		948	a case where this is useful.
		949
		950	Example: Create a watcher for the IO::AIO module and store it in
		951	C<$WATCHER>. Only do so after the event loop is initialised, though.
		952
		953	our WATCHER;
		954
		955	my $guard = AnyEvent::post_detect {
		956	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		957	};
		958
		959	# the ||= is important in case post_detect immediately runs the block,
		960	# as to not clobber the newly-created watcher. assigning both watcher and
		961	# post_detect guard to the same variable has the advantage of users being
		962	# able to just C<undef $WATCHER> if the watcher causes them grief.
		963
		964	$WATCHER ||= $guard;
		965
		966	=item @AnyEvent::post_detect
		967
		968	If there are any code references in this array (you can C<push> to it
		969	before or after loading AnyEvent), then they will called directly after
		970	the event loop has been chosen.
		971
		972	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		973	if it is defined then the event loop has already been detected, and the
		974	array will be ignored.
		975
		976	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		977	it, as it takes care of these details.
		978
		979	This variable is mainly useful for modules that can do something useful
		980	when AnyEvent is used and thus want to know when it is initialised, but do
		981	not need to even load it by default. This array provides the means to hook
		982	into AnyEvent passively, without loading it.
		983
		984	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		985	together, you could put this into Coro (this is the actual code used by
		986	Coro to accomplish this):
		987
		988	if (defined $AnyEvent::MODEL) {
		989	# AnyEvent already initialised, so load Coro::AnyEvent
		990	require Coro::AnyEvent;
		991	} else {
		992	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		993	# as soon as it is
		994	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		995	}
438		996
439	=back	997	=back
440		998
441	=head1 WHAT TO DO IN A MODULE	999	=head1 WHAT TO DO IN A MODULE
442		1000
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	1004	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	1005	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	1006	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	1007	to load the event module first.
450		1008
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	1009	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	1010	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	1011	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	1012	events is to stay interactive.
455		1013
456	It is fine, however, to call C<< ->wait >> when the user of your module	1014	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	1015	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	1016	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	1017	freely, as the user of your module knows what she is doing. always).
460		1018
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	1019	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		1020
463	There will always be a single main program - the only place that should	1021	There will always be a single main program - the only place that should
…		…
465		1023
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1024	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	1025	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	1026	decide which implementation to chose if some module relies on it.
469		1027
470	If the main program relies on a specific event model. For example, in	1028	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	1029	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	1030	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	1031	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	1032	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	1033	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	1034	might chose the wrong one unless you load the correct one yourself.
477		1035
478	You can chose to use a rather inefficient pure-perl implementation by	1036	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	1037	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	1038	everywhere, but letting AnyEvent chose the model is generally better.
		1039
		1040	=head2 MAINLOOP EMULATION
		1041
		1042	Sometimes (often for short test scripts, or even standalone programs who
		1043	only want to use AnyEvent), you do not want to run a specific event loop.
		1044
		1045	In that case, you can use a condition variable like this:
		1046
		1047	AnyEvent->condvar->recv;
		1048
		1049	This has the effect of entering the event loop and looping forever.
		1050
		1051	Note that usually your program has some exit condition, in which case
		1052	it is better to use the "traditional" approach of storing a condition
		1053	variable somewhere, waiting for it, and sending it when the program should
		1054	exit cleanly.
		1055
		1056
		1057	=head1 OTHER MODULES
		1058
		1059	The following is a non-exhaustive list of additional modules that use
		1060	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
		1061	modules and other event loops in the same program. Some of the modules
		1062	come with AnyEvent, most are available via CPAN.
		1063
		1064	=over 4
		1065
		1066	=item L<AnyEvent::Util>
		1067
		1068	Contains various utility functions that replace often-used but blocking
		1069	functions such as C<inet_aton> by event-/callback-based versions.
		1070
		1071	=item L<AnyEvent::Socket>
		1072
		1073	Provides various utility functions for (internet protocol) sockets,
		1074	addresses and name resolution. Also functions to create non-blocking tcp
		1075	connections or tcp servers, with IPv6 and SRV record support and more.
		1076
		1077	=item L<AnyEvent::Handle>
		1078
		1079	Provide read and write buffers, manages watchers for reads and writes,
		1080	supports raw and formatted I/O, I/O queued and fully transparent and
		1081	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1082
		1083	=item L<AnyEvent::DNS>
		1084
		1085	Provides rich asynchronous DNS resolver capabilities.
		1086
		1087	=item L<AnyEvent::HTTP>
		1088
		1089	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1090	HTTP requests.
		1091
		1092	=item L<AnyEvent::HTTPD>
		1093
		1094	Provides a simple web application server framework.
		1095
		1096	=item L<AnyEvent::FastPing>
		1097
		1098	The fastest ping in the west.
		1099
		1100	=item L<AnyEvent::DBI>
		1101
		1102	Executes L<DBI> requests asynchronously in a proxy process.
		1103
		1104	=item L<AnyEvent::AIO>
		1105
		1106	Truly asynchronous I/O, should be in the toolbox of every event
		1107	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1108	together.
		1109
		1110	=item L<AnyEvent::BDB>
		1111
		1112	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1113	L<BDB> and AnyEvent together.
		1114
		1115	=item L<AnyEvent::GPSD>
		1116
		1117	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1118
		1119	=item L<AnyEvent::IRC>
		1120
		1121	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1122
		1123	=item L<AnyEvent::XMPP>
		1124
		1125	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1126	Net::XMPP2>.
		1127
		1128	=item L<AnyEvent::IGS>
		1129
		1130	A non-blocking interface to the Internet Go Server protocol (used by
		1131	L<App::IGS>).
		1132
		1133	=item L<Net::FCP>
		1134
		1135	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		1136	of AnyEvent.
		1137
		1138	=item L<Event::ExecFlow>
		1139
		1140	High level API for event-based execution flow control.
		1141
		1142	=item L<Coro>
		1143
		1144	Has special support for AnyEvent via L<Coro::AnyEvent>.
		1145
		1146	=back
481		1147
482	=cut	1148	=cut
483		1149
484	package AnyEvent;	1150	package AnyEvent;
485		1151
486	no warnings;	1152	# basically a tuned-down version of common::sense
487	use strict;	1153	sub common_sense {
		1154	# from common:.sense 1.0
		1155	${^WARNING_BITS} = "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x00";
		1156	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1157	$^H |= 0x00000600;
		1158	}
488		1159
		1160	BEGIN { AnyEvent::common_sense }
		1161
489	use Carp;	1162	use Carp ();
490		1163
491	our $VERSION = '3.3';	1164	our $VERSION = '5.261';
492	our $MODEL;	1165	our $MODEL;
493		1166
494	our $AUTOLOAD;	1167	our $AUTOLOAD;
495	our @ISA;	1168	our @ISA;
496		1169
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498
499	our @REGISTRY;	1170	our @REGISTRY;
500		1171
		1172	our $VERBOSE;
		1173
		1174	BEGIN {
		1175	require "AnyEvent/constants.pl";
		1176
		1177	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1178
		1179	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1180	if ${^TAINT};
		1181
		1182	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1183
		1184	}
		1185
		1186	our $MAX_SIGNAL_LATENCY = 10;
		1187
		1188	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1189
		1190	{
		1191	my $idx;
		1192	$PROTOCOL{$_} = ++$idx
		1193	for reverse split /\s*,\s*/,
		1194	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1195	}
		1196
501	my @models = (	1197	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	1198	[EV:: => AnyEvent::Impl::EV:: , 1],
		1199	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
		1200	# everything below here will not (normally) be autoprobed
		1201	# as the pureperl backend should work everywhere
		1202	# and is usually faster
505	[Event:: => AnyEvent::Impl::Event::],	1203	[Event:: => AnyEvent::Impl::Event::, 1],
506	[Glib:: => AnyEvent::Impl::Glib::],	1204	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1205	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1206	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
507	[Tk:: => AnyEvent::Impl::Tk::],	1207	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1208	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1209	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
508	[Wx:: => AnyEvent::Impl::POE::],	1210	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],	1211	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1212	# IO::Async is just too broken - we would need workarounds for its
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1213	# byzantine signal and broken child handling, among others.
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1214	# IO::Async is rather hard to detect, as it doesn't have any
		1215	# obvious default class.
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1216	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1217	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1218	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1219	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
515	);	1220	);
516		1221
517	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1222	our %method = map +($_ => 1),
		1223	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1224
		1225	our @post_detect;
		1226
		1227	sub post_detect(&) {
		1228	my ($cb) = @_;
		1229
		1230	push @post_detect, $cb;
		1231
		1232	defined wantarray
		1233	? bless \$cb, "AnyEvent::Util::postdetect"
		1234	: ()
		1235	}
		1236
		1237	sub AnyEvent::Util::postdetect::DESTROY {
		1238	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1239	}
518		1240
519	sub detect() {	1241	sub detect() {
		1242	# free some memory
		1243	*detect = sub () { $MODEL };
		1244
		1245	local $!; # for good measure
		1246	local $SIG{__DIE__};
		1247
		1248	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1249	my $model = "AnyEvent::Impl::$1";
		1250	if (eval "require $model") {
		1251	$MODEL = $model;
		1252	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
		1253	} else {
		1254	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
		1255	}
		1256	}
		1257
		1258	# check for already loaded models
520	unless ($MODEL) {	1259	unless ($MODEL) {
521	no strict 'refs';	1260	for (@REGISTRY, @models) {
522		1261	my ($package, $model) = @$_;
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1262	if (${"$package\::VERSION"} > 0) {
524	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	1263	if (eval "require $model") {
526	$MODEL = $model;	1264	$MODEL = $model;
527	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1265	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
528	} else {	1266	last;
529	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1267	}
530	}	1268	}
531	}	1269	}
532		1270
533	# check for already loaded models
534	unless ($MODEL) {	1271	unless ($MODEL) {
		1272	# try to autoload a model
535	for (@REGISTRY, @models) {	1273	for (@REGISTRY, @models) {
536	my ($package, $model) = @$_;	1274	my ($package, $model, $autoload) = @$_;
		1275	if (
		1276	$autoload
		1277	and eval "require $package"
537	if (${"$package\::VERSION"} > 0) {	1278	and ${"$package\::VERSION"} > 0
538	if (eval "require $model") {	1279	and eval "require $model"
		1280	) {
539	$MODEL = $model;	1281	$MODEL = $model;
540	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1282	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
541	last;	1283	last;
542	}
543	}	1284	}
544	}	1285	}
545		1286
546	unless ($MODEL) {
547	# try to load a model
548
549	for (@REGISTRY, @models) {
550	my ($package, $model) = @$_;
551	if (eval "require $package"
552	and ${"$package\::VERSION"} > 0
553	and eval "require $model") {
554	$MODEL = $model;
555	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
556	last;
557	}
558	}
559
560	$MODEL	1287	$MODEL
561	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1288	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
562	}
563	}	1289	}
564
565	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
567	}	1290	}
		1291
		1292	@models = (); # free probe data
		1293
		1294	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1295	unshift @ISA, $MODEL;
		1296
		1297	# now nuke some methods that are overriden by the backend.
		1298	# SUPER is not allowed.
		1299	for (qw(time signal child idle)) {
		1300	undef &{"AnyEvent::Base::$_"}
		1301	if defined &{"$MODEL\::$_"};
		1302	}
		1303
		1304	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1305
		1306	(shift @post_detect)->() while @post_detect;
		1307
		1308	*post_detect = sub(&) {
		1309	shift->();
		1310
		1311	undef
		1312	};
568		1313
569	$MODEL	1314	$MODEL
570	}	1315	}
571		1316
572	sub AUTOLOAD {	1317	sub AUTOLOAD {
573	(my $func = $AUTOLOAD) =~ s/.*://;	1318	(my $func = $AUTOLOAD) =~ s/.*://;
574		1319
575	$method{$func}	1320	$method{$func}
576	or croak "$func: not a valid method for AnyEvent objects";	1321	or Carp::croak "$func: not a valid AnyEvent class method";
577		1322
578	detect unless $MODEL;	1323	detect;
579		1324
580	my $class = shift;	1325	my $class = shift;
581	$class->$func (@_);	1326	$class->$func (@_);
582	}	1327	}
583		1328
		1329	# utility function to dup a filehandle. this is used by many backends
		1330	# to support binding more than one watcher per filehandle (they usually
		1331	# allow only one watcher per fd, so we dup it to get a different one).
		1332	sub _dupfh($$;$$) {
		1333	my ($poll, $fh, $r, $w) = @_;
		1334
		1335	# cygwin requires the fh mode to be matching, unix doesn't
		1336	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1337
		1338	open my $fh2, $mode, $fh
		1339	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1340
		1341	# we assume CLOEXEC is already set by perl in all important cases
		1342
		1343	($fh2, $rw)
		1344	}
		1345
		1346	=head1 SIMPLIFIED AE API
		1347
		1348	Starting with version 5.0, AnyEvent officially supports a second, much
		1349	simpler, API that is designed to reduce the calling, typing and memory
		1350	overhead by using function call syntax and a fixed number of parameters.
		1351
		1352	See the L<AE> manpage for details.
		1353
		1354	=cut
		1355
		1356	package AE;
		1357
		1358	our $VERSION = $AnyEvent::VERSION;
		1359
		1360	# fall back to the main API by default - backends and AnyEvent::Base
		1361	# implementations can overwrite these.
		1362
		1363	sub io($$$) {
		1364	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1365	}
		1366
		1367	sub timer($$$) {
		1368	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1369	}
		1370
		1371	sub signal($$) {
		1372	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1373	}
		1374
		1375	sub child($$) {
		1376	AnyEvent->child (pid => $_[0], cb => $_[1])
		1377	}
		1378
		1379	sub idle($) {
		1380	AnyEvent->idle (cb => $_[0])
		1381	}
		1382
		1383	sub cv(;&) {
		1384	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1385	}
		1386
		1387	sub now() {
		1388	AnyEvent->now
		1389	}
		1390
		1391	sub now_update() {
		1392	AnyEvent->now_update
		1393	}
		1394
		1395	sub time() {
		1396	AnyEvent->time
		1397	}
		1398
584	package AnyEvent::Base;	1399	package AnyEvent::Base;
585		1400
		1401	# default implementations for many methods
		1402
		1403	sub time {
		1404	eval q{ # poor man's autoloading {}
		1405	# probe for availability of Time::HiRes
		1406	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1407	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1408	*AE::time = \&Time::HiRes::time;
		1409	# if (eval "use POSIX (); (POSIX::times())...
		1410	} else {
		1411	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1412	*AE::time = sub (){ time }; # epic fail
		1413	}
		1414
		1415	*time = sub { AE::time }; # different prototypes
		1416	};
		1417	die if $@;
		1418
		1419	&time
		1420	}
		1421
		1422	*now = \&time;
		1423
		1424	sub now_update { }
		1425
586	# default implementation for ->condvar, ->wait, ->broadcast	1426	# default implementation for ->condvar
587		1427
588	sub condvar {	1428	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	1429	eval q{ # poor man's autoloading {}
590	}	1430	*condvar = sub {
		1431	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1432	};
591		1433
592	sub AnyEvent::Base::CondVar::broadcast {	1434	*AE::cv = sub (;&) {
593	${$_[0]}++;	1435	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
594	}	1436	};
		1437	};
		1438	die if $@;
595		1439
596	sub AnyEvent::Base::CondVar::wait {	1440	&condvar
597	AnyEvent->one_event while !${$_[0]};
598	}	1441	}
599		1442
600	# default implementation for ->signal	1443	# default implementation for ->signal
601		1444
602	our %SIG_CB;	1445	our $HAVE_ASYNC_INTERRUPT;
		1446
		1447	sub _have_async_interrupt() {
		1448	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1449	&& eval "use Async::Interrupt 1.02 (); 1")
		1450	unless defined $HAVE_ASYNC_INTERRUPT;
		1451
		1452	$HAVE_ASYNC_INTERRUPT
		1453	}
		1454
		1455	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1456	our (%SIG_ASY, %SIG_ASY_W);
		1457	our ($SIG_COUNT, $SIG_TW);
		1458
		1459	# install a dummy wakeup watcher to reduce signal catching latency
		1460	# used by Impls
		1461	sub _sig_add() {
		1462	unless ($SIG_COUNT++) {
		1463	# try to align timer on a full-second boundary, if possible
		1464	my $NOW = AE::now;
		1465
		1466	$SIG_TW = AE::timer
		1467	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1468	$MAX_SIGNAL_LATENCY,
		1469	sub { } # just for the PERL_ASYNC_CHECK
		1470	;
		1471	}
		1472	}
		1473
		1474	sub _sig_del {
		1475	undef $SIG_TW
		1476	unless --$SIG_COUNT;
		1477	}
		1478
		1479	our $_sig_name_init; $_sig_name_init = sub {
		1480	eval q{ # poor man's autoloading {}
		1481	undef $_sig_name_init;
		1482
		1483	if (_have_async_interrupt) {
		1484	*sig2num = \&Async::Interrupt::sig2num;
		1485	*sig2name = \&Async::Interrupt::sig2name;
		1486	} else {
		1487	require Config;
		1488
		1489	my %signame2num;
		1490	@signame2num{ split ' ', $Config::Config{sig_name} }
		1491	= split ' ', $Config::Config{sig_num};
		1492
		1493	my @signum2name;
		1494	@signum2name[values %signame2num] = keys %signame2num;
		1495
		1496	*sig2num = sub($) {
		1497	$_[0] > 0 ? shift : $signame2num{+shift}
		1498	};
		1499	*sig2name = sub ($) {
		1500	$_[0] > 0 ? $signum2name[+shift] : shift
		1501	};
		1502	}
		1503	};
		1504	die if $@;
		1505	};
		1506
		1507	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1508	sub sig2name($) { &$_sig_name_init; &sig2name }
603		1509
604	sub signal {	1510	sub signal {
		1511	eval q{ # poor man's autoloading {}
		1512	# probe for availability of Async::Interrupt
		1513	if (_have_async_interrupt) {
		1514	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1515
		1516	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1517	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1518
		1519	} else {
		1520	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1521
		1522	if (AnyEvent::WIN32) {
		1523	require AnyEvent::Util;
		1524
		1525	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1526	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1527	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1528	} else {
		1529	pipe $SIGPIPE_R, $SIGPIPE_W;
		1530	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1531	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1532
		1533	# not strictly required, as $^F is normally 2, but let's make sure...
		1534	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1535	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1536	}
		1537
		1538	$SIGPIPE_R
		1539	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1540
		1541	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1542	}
		1543
		1544	*signal = $HAVE_ASYNC_INTERRUPT
		1545	? sub {
605	my (undef, %arg) = @_;	1546	my (undef, %arg) = @_;
606		1547
		1548	# async::interrupt
607	my $signal = uc $arg{signal}	1549	my $signal = sig2num $arg{signal};
608	or Carp::croak "required option 'signal' is missing";
609
610	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1550	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1551
		1552	$SIG_ASY{$signal} ||= new Async::Interrupt
		1553	cb => sub { undef $SIG_EV{$signal} },
		1554	signal => $signal,
		1555	pipe => [$SIGPIPE_R->filenos],
		1556	pipe_autodrain => 0,
		1557	;
		1558
		1559	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1560	}
		1561	: sub {
		1562	my (undef, %arg) = @_;
		1563
		1564	# pure perl
		1565	my $signal = sig2name $arg{signal};
		1566	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1567
611	$SIG{$signal} ||= sub {	1568	$SIG{$signal} ||= sub {
		1569	local $!;
		1570	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1571	undef $SIG_EV{$signal};
		1572	};
		1573
		1574	# can't do signal processing without introducing races in pure perl,
		1575	# so limit the signal latency.
		1576	_sig_add;
		1577
		1578	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1579	}
		1580	;
		1581
		1582	*AnyEvent::Base::signal::DESTROY = sub {
		1583	my ($signal, $cb) = @{$_[0]};
		1584
		1585	_sig_del;
		1586
		1587	delete $SIG_CB{$signal}{$cb};
		1588
		1589	$HAVE_ASYNC_INTERRUPT
		1590	? delete $SIG_ASY{$signal}
		1591	: # delete doesn't work with older perls - they then
		1592	# print weird messages, or just unconditionally exit
		1593	# instead of getting the default action.
		1594	undef $SIG{$signal}
		1595	unless keys %{ $SIG_CB{$signal} };
		1596	};
		1597
		1598	*_signal_exec = sub {
		1599	$HAVE_ASYNC_INTERRUPT
		1600	? $SIGPIPE_R->drain
		1601	: sysread $SIGPIPE_R, (my $dummy), 9;
		1602
		1603	while (%SIG_EV) {
		1604	for (keys %SIG_EV) {
		1605	delete $SIG_EV{$_};
612	$_->() for values %{ $SIG_CB{$signal} || {} };	1606	$_->() for values %{ $SIG_CB{$_} || {} };
		1607	}
		1608	}
		1609	};
613	};	1610	};
		1611	die if $@;
614		1612
615	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1613	&signal
616	}
617
618	sub AnyEvent::Base::Signal::DESTROY {
619	my ($signal, $cb) = @{$_[0]};
620
621	delete $SIG_CB{$signal}{$cb};
622
623	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
624	}	1614	}
625		1615
626	# default implementation for ->child	1616	# default implementation for ->child
627		1617
628	our %PID_CB;	1618	our %PID_CB;
629	our $CHLD_W;	1619	our $CHLD_W;
630	our $CHLD_DELAY_W;	1620	our $CHLD_DELAY_W;
631	our $PID_IDLE;
632	our $WNOHANG;	1621	our $WNOHANG;
633		1622
634	sub _child_wait {	1623	# used by many Impl's
635	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1624	sub _emit_childstatus($$) {
		1625	my (undef, $rpid, $rstatus) = @_;
		1626
		1627	$_->($rpid, $rstatus)
636	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1628	for values %{ $PID_CB{$rpid} || {} },
637	(values %{ $PID_CB{0} || {} });	1629	values %{ $PID_CB{0} || {} };
638	}
639
640	undef $PID_IDLE;
641	}
642
643	sub _sigchld {
644	# make sure we deliver these changes "synchronous" with the event loop.
645	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
646	undef $CHLD_DELAY_W;
647	&_child_wait;
648	});
649	}	1630	}
650		1631
651	sub child {	1632	sub child {
		1633	eval q{ # poor man's autoloading {}
		1634	*_sigchld = sub {
		1635	my $pid;
		1636
		1637	AnyEvent->_emit_childstatus ($pid, $?)
		1638	while ($pid = waitpid -1, $WNOHANG) > 0;
		1639	};
		1640
		1641	*child = sub {
652	my (undef, %arg) = @_;	1642	my (undef, %arg) = @_;
653		1643
654	defined (my $pid = $arg{pid} + 0)	1644	defined (my $pid = $arg{pid} + 0)
655	or Carp::croak "required option 'pid' is missing";	1645	or Carp::croak "required option 'pid' is missing";
656		1646
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1647	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1648
659	unless ($WNOHANG) {	1649	# WNOHANG is almost cetrainly 1 everywhere
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1650	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
661	}	1651	? 1
		1652	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
662		1653
663	unless ($CHLD_W) {	1654	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1655	$CHLD_W = AE::signal CHLD => \&_sigchld;
665	# child could be a zombie already, so make at least one round	1656	# child could be a zombie already, so make at least one round
666	&_sigchld;	1657	&_sigchld;
667	}	1658	}
668		1659
669	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1660	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
670	}	1661	};
671		1662
672	sub AnyEvent::Base::Child::DESTROY {	1663	*AnyEvent::Base::child::DESTROY = sub {
673	my ($pid, $cb) = @{$_[0]};	1664	my ($pid, $cb) = @{$_[0]};
674		1665
675	delete $PID_CB{$pid}{$cb};	1666	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1667	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1668
678	undef $CHLD_W unless keys %PID_CB;	1669	undef $CHLD_W unless keys %PID_CB;
		1670	};
		1671	};
		1672	die if $@;
		1673
		1674	&child
679	}	1675	}
		1676
		1677	# idle emulation is done by simply using a timer, regardless
		1678	# of whether the process is idle or not, and not letting
		1679	# the callback use more than 50% of the time.
		1680	sub idle {
		1681	eval q{ # poor man's autoloading {}
		1682	*idle = sub {
		1683	my (undef, %arg) = @_;
		1684
		1685	my ($cb, $w, $rcb) = $arg{cb};
		1686
		1687	$rcb = sub {
		1688	if ($cb) {
		1689	$w = _time;
		1690	&$cb;
		1691	$w = _time - $w;
		1692
		1693	# never use more then 50% of the time for the idle watcher,
		1694	# within some limits
		1695	$w = 0.0001 if $w < 0.0001;
		1696	$w = 5 if $w > 5;
		1697
		1698	$w = AE::timer $w, 0, $rcb;
		1699	} else {
		1700	# clean up...
		1701	undef $w;
		1702	undef $rcb;
		1703	}
		1704	};
		1705
		1706	$w = AE::timer 0.05, 0, $rcb;
		1707
		1708	bless \\$cb, "AnyEvent::Base::idle"
		1709	};
		1710
		1711	*AnyEvent::Base::idle::DESTROY = sub {
		1712	undef $${$_[0]};
		1713	};
		1714	};
		1715	die if $@;
		1716
		1717	&idle
		1718	}
		1719
		1720	package AnyEvent::CondVar;
		1721
		1722	our @ISA = AnyEvent::CondVar::Base::;
		1723
		1724	package AnyEvent::CondVar::Base;
		1725
		1726	#use overload
		1727	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1728	# fallback => 1;
		1729
		1730	# save 300+ kilobytes by dirtily hardcoding overloading
		1731	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1732	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1733	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1734	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1735
		1736	our $WAITING;
		1737
		1738	sub _send {
		1739	# nop
		1740	}
		1741
		1742	sub send {
		1743	my $cv = shift;
		1744	$cv->{_ae_sent} = [@_];
		1745	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1746	$cv->_send;
		1747	}
		1748
		1749	sub croak {
		1750	$_[0]{_ae_croak} = $_[1];
		1751	$_[0]->send;
		1752	}
		1753
		1754	sub ready {
		1755	$_[0]{_ae_sent}
		1756	}
		1757
		1758	sub _wait {
		1759	$WAITING
		1760	and !$_[0]{_ae_sent}
		1761	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1762
		1763	local $WAITING = 1;
		1764	AnyEvent->one_event while !$_[0]{_ae_sent};
		1765	}
		1766
		1767	sub recv {
		1768	$_[0]->_wait;
		1769
		1770	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1771	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1772	}
		1773
		1774	sub cb {
		1775	my $cv = shift;
		1776
		1777	@_
		1778	and $cv->{_ae_cb} = shift
		1779	and $cv->{_ae_sent}
		1780	and (delete $cv->{_ae_cb})->($cv);
		1781
		1782	$cv->{_ae_cb}
		1783	}
		1784
		1785	sub begin {
		1786	++$_[0]{_ae_counter};
		1787	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1788	}
		1789
		1790	sub end {
		1791	return if --$_[0]{_ae_counter};
		1792	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1793	}
		1794
		1795	# undocumented/compatibility with pre-3.4
		1796	*broadcast = \&send;
		1797	*wait = \&_wait;
		1798
		1799	=head1 ERROR AND EXCEPTION HANDLING
		1800
		1801	In general, AnyEvent does not do any error handling - it relies on the
		1802	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1803	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1804	checking of all AnyEvent methods, however, which is highly useful during
		1805	development.
		1806
		1807	As for exception handling (i.e. runtime errors and exceptions thrown while
		1808	executing a callback), this is not only highly event-loop specific, but
		1809	also not in any way wrapped by this module, as this is the job of the main
		1810	program.
		1811
		1812	The pure perl event loop simply re-throws the exception (usually
		1813	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1814	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1815	so on.
		1816
		1817	=head1 ENVIRONMENT VARIABLES
		1818
		1819	The following environment variables are used by this module or its
		1820	submodules.
		1821
		1822	Note that AnyEvent will remove I<all> environment variables starting with
		1823	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1824	enabled.
		1825
		1826	=over 4
		1827
		1828	=item C<PERL_ANYEVENT_VERBOSE>
		1829
		1830	By default, AnyEvent will be completely silent except in fatal
		1831	conditions. You can set this environment variable to make AnyEvent more
		1832	talkative.
		1833
		1834	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1835	conditions, such as not being able to load the event model specified by
		1836	C<PERL_ANYEVENT_MODEL>.
		1837
		1838	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1839	model it chooses.
		1840
		1841	When set to C<8> or higher, then AnyEvent will report extra information on
		1842	which optional modules it loads and how it implements certain features.
		1843
		1844	=item C<PERL_ANYEVENT_STRICT>
		1845
		1846	AnyEvent does not do much argument checking by default, as thorough
		1847	argument checking is very costly. Setting this variable to a true value
		1848	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1849	check the arguments passed to most method calls. If it finds any problems,
		1850	it will croak.
		1851
		1852	In other words, enables "strict" mode.
		1853
		1854	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1855	>>, it is definitely recommended to keep it off in production. Keeping
		1856	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1857	can be very useful, however.
		1858
		1859	=item C<PERL_ANYEVENT_MODEL>
		1860
		1861	This can be used to specify the event model to be used by AnyEvent, before
		1862	auto detection and -probing kicks in. It must be a string consisting
		1863	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1864	and the resulting module name is loaded and if the load was successful,
		1865	used as event model. If it fails to load AnyEvent will proceed with
		1866	auto detection and -probing.
		1867
		1868	This functionality might change in future versions.
		1869
		1870	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1871	could start your program like this:
		1872
		1873	PERL_ANYEVENT_MODEL=Perl perl ...
		1874
		1875	=item C<PERL_ANYEVENT_PROTOCOLS>
		1876
		1877	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1878	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1879	of auto probing).
		1880
		1881	Must be set to a comma-separated list of protocols or address families,
		1882	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1883	used, and preference will be given to protocols mentioned earlier in the
		1884	list.
		1885
		1886	This variable can effectively be used for denial-of-service attacks
		1887	against local programs (e.g. when setuid), although the impact is likely
		1888	small, as the program has to handle conenction and other failures anyways.
		1889
		1890	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1891	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1892	- only support IPv4, never try to resolve or contact IPv6
		1893	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1894	IPv6, but prefer IPv6 over IPv4.
		1895
		1896	=item C<PERL_ANYEVENT_EDNS0>
		1897
		1898	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1899	for DNS. This extension is generally useful to reduce DNS traffic, but
		1900	some (broken) firewalls drop such DNS packets, which is why it is off by
		1901	default.
		1902
		1903	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1904	EDNS0 in its DNS requests.
		1905
		1906	=item C<PERL_ANYEVENT_MAX_FORKS>
		1907
		1908	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1909	will create in parallel.
		1910
		1911	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1912
		1913	The default value for the C<max_outstanding> parameter for the default DNS
		1914	resolver - this is the maximum number of parallel DNS requests that are
		1915	sent to the DNS server.
		1916
		1917	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1918
		1919	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1920	configuration) in the default resolver. When set to the empty string, no
		1921	default config will be used.
		1922
		1923	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1924
		1925	When neither C<ca_file> nor C<ca_path> was specified during
		1926	L<AnyEvent::TLS> context creation, and either of these environment
		1927	variables exist, they will be used to specify CA certificate locations
		1928	instead of a system-dependent default.
		1929
		1930	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1931
		1932	When these are set to C<1>, then the respective modules are not
		1933	loaded. Mostly good for testing AnyEvent itself.
		1934
		1935	=back
680		1936
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1937	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1938
683	This is an advanced topic that you do not normally need to use AnyEvent in	1939	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1940	a module. This section is only of use to event loop authors who want to
…		…
718		1974
719	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1975	I<rxvt-unicode> also cheats a bit by not providing blocking access to
720	condition variables: code blocking while waiting for a condition will	1976	condition variables: code blocking while waiting for a condition will
721	C<die>. This still works with most modules/usages, and blocking calls must	1977	C<die>. This still works with most modules/usages, and blocking calls must
722	not be done in an interactive application, so it makes sense.	1978	not be done in an interactive application, so it makes sense.
723
724	=head1 ENVIRONMENT VARIABLES
725
726	The following environment variables are used by this module:
727
728	=over 4
729
730	=item C<PERL_ANYEVENT_VERBOSE>
731
732	By default, AnyEvent will be completely silent except in fatal
733	conditions. You can set this environment variable to make AnyEvent more
734	talkative.
735
736	When set to C<1> or higher, causes AnyEvent to warn about unexpected
737	conditions, such as not being able to load the event model specified by
738	C<PERL_ANYEVENT_MODEL>.
739
740	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
741	model it chooses.
742
743	=item C<PERL_ANYEVENT_MODEL>
744
745	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.
751
752	This functionality might change in future versions.
753
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:
756
757	PERL_ANYEVENT_MODEL=Perl perl ...
758
759	=back
760		1979
761	=head1 EXAMPLE PROGRAM	1980	=head1 EXAMPLE PROGRAM
762		1981
763	The following program uses an I/O watcher to read data from STDIN, a timer	1982	The following program uses an I/O watcher to read data from STDIN, a timer
764	to display a message once per second, and a condition variable to quit the	1983	to display a message once per second, and a condition variable to quit the
…		…
773	poll => 'r',	1992	poll => 'r',
774	cb => sub {	1993	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1994	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1995	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1996	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1997	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1998	},
780	);	1999	);
781		2000
782	my $time_watcher; # can only be used once
783
784	sub new_timer {
785	$timer = AnyEvent->timer (after => 1, cb => sub {	2001	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
786	warn "timeout\n"; # print 'timeout' about every second	2002	warn "timeout\n"; # print 'timeout' at most every second
787	&new_timer; # and restart the time
788	});	2003	});
789	}
790		2004
791	new_timer; # create first timer
792
793	$cv->wait; # wait until user enters /^q/i	2005	$cv->recv; # wait until user enters /^q/i
794		2006
795	=head1 REAL-WORLD EXAMPLE	2007	=head1 REAL-WORLD EXAMPLE
796		2008
797	Consider the L<Net::FCP> module. It features (among others) the following	2009	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	2010	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	2060	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	2061	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	2062	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		2063
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	2064	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	2065	result and signals any possible waiters that the request has finished:
854		2066
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	2067	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		2068
857	if (end-of-file or data complete) {	2069	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	2070	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	2071	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	2072	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	2073	}
862		2074
863	The C<result> method, finally, just waits for the finished signal (if the	2075	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	2076	request was already finished, it doesn't wait, of course, and returns the
865	data:	2077	data:
866		2078
867	$txn->{finished}->wait;	2079	$txn->{finished}->recv;
868	return $txn->{result};	2080	return $txn->{result};
869		2081
870	The actual code goes further and collects all errors (C<die>s, exceptions)	2082	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	2083	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	2084	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	2085	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	2086	problems get reported to the code that tries to use the result, not in a
875	random callback.	2087	random callback.
876		2088
877	All of this enables the following usage styles:	2089	All of this enables the following usage styles:
878		2090
879	1. Blocking:	2091	1. Blocking:
…		…
907		2119
908	my $quit = AnyEvent->condvar;	2120	my $quit = AnyEvent->condvar;
909		2121
910	$fcp->txn_client_get ($url)->cb (sub {	2122	$fcp->txn_client_get ($url)->cb (sub {
911	...	2123	...
912	$quit->broadcast;	2124	$quit->send;
913	});	2125	});
914		2126
915	$quit->wait;	2127	$quit->recv;
916		2128
917		2129
918	=head1 BENCHMARKS	2130	=head1 BENCHMARKS
919		2131
920	To give you an idea of the performance and overheads that AnyEvent adds	2132	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	2134	of various event loops I prepared some benchmarks.
923		2135
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	2136	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		2137
926	Here is a benchmark of various supported event models used natively and	2138	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	2139	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2140	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	2141	which it is), lets them fire exactly once and destroys them again.
930		2142
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2143	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	2144	distribution. It uses the L<AE> interface, which makes a real difference
		2145	for the EV and Perl backends only.
933		2146
934	=head3 Explanation of the columns	2147	=head3 Explanation of the columns
935		2148
936	I<watcher> is the number of event watchers created/destroyed. Since	2149	I<watcher> is the number of event watchers created/destroyed. Since
937	different event models feature vastly different performances, each event	2150	different event models feature vastly different performances, each event
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	2162	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	2163	and memory usage is not included in the figures.
951		2164
952	I<invoke> is the time, in microseconds, used to invoke a simple	2165	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	2166	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	2167	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	2168	signal the end of this phase.
956		2169
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	2170	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	2171	watcher.
959		2172
960	=head3 Results	2173	=head3 Results
961		2174
962	name watchers bytes create invoke destroy comment	2175	name watchers bytes create invoke destroy comment
963	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2176	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
964	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2177	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
965	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2178	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
966	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2179	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
967	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2180	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
968	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2181	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2182	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2183	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
969	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2184	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
970	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2185	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
971	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2186	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
972	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2187	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
973		2188
974	=head3 Discussion	2189	=head3 Discussion
975		2190
976	The benchmark does I<not> measure scalability of the event loop very	2191	The benchmark does I<not> measure scalability of the event loop very
977	well. For example, a select-based event loop (such as the pure perl one)	2192	well. For example, a select-based event loop (such as the pure perl one)
…		…
989	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2204	benchmark machine, handling an event takes roughly 1600 CPU cycles with
990	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2205	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
991	cycles with POE.	2206	cycles with POE.
992		2207
993	C<EV> is the sole leader regarding speed and memory use, which are both	2208	C<EV> is the sole leader regarding speed and memory use, which are both
994	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2209	maximal/minimal, respectively. When using the L<AE> API there is zero
		2210	overhead (when going through the AnyEvent API create is about 5-6 times
		2211	slower, with other times being equal, so still uses far less memory than
995	far less memory than any other event loop and is still faster than Event	2212	any other event loop and is still faster than Event natively).
996	natively.
997		2213
998	The pure perl implementation is hit in a few sweet spots (both the	2214	The pure perl implementation is hit in a few sweet spots (both the
999	constant timeout and the use of a single fd hit optimisations in the perl	2215	constant timeout and the use of a single fd hit optimisations in the perl
1000	interpreter and the backend itself). Nevertheless this shows that it	2216	interpreter and the backend itself). Nevertheless this shows that it
1001	adds very little overhead in itself. Like any select-based backend its	2217	adds very little overhead in itself. Like any select-based backend its
1002	performance becomes really bad with lots of file descriptors (and few of	2218	performance becomes really bad with lots of file descriptors (and few of
1003	them active), of course, but this was not subject of this benchmark.	2219	them active), of course, but this was not subject of this benchmark.
1004		2220
1005	The C<Event> module has a relatively high setup and callback invocation	2221	The C<Event> module has a relatively high setup and callback invocation
1006	cost, but overall scores in on the third place.	2222	cost, but overall scores in on the third place.
		2223
		2224	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2225	when using its pure perl backend.
1007		2226
1008	C<Glib>'s memory usage is quite a bit higher, but it features a	2227	C<Glib>'s memory usage is quite a bit higher, but it features a
1009	faster callback invocation and overall ends up in the same class as	2228	faster callback invocation and overall ends up in the same class as
1010	C<Event>. However, Glib scales extremely badly, doubling the number of	2229	C<Event>. However, Glib scales extremely badly, doubling the number of
1011	watchers increases the processing time by more than a factor of four,	2230	watchers increases the processing time by more than a factor of four,
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	2238	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	2239	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	2240	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	2241	above).
1023		2242
1024	C<POE>, regardless of underlying event loop (whether using its pure	2243	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	2244	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	2245	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	2246	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	2247	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	2248	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	2249	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		2250	implementation.
		2251
1031	implementation. The design of the POE adaptor class in AnyEvent can not	2252	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	2253	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	2254	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	2255	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		2256	using multiple sessions is not a good approach, especially regarding
		2257	memory usage, even the author of POE could not come up with a faster
		2258	design).
1035		2259
1036	=head3 Summary	2260	=head3 Summary
1037		2261
1038	=over 4	2262	=over 4
1039		2263
…		…
1050		2274
1051	=back	2275	=back
1052		2276
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	2277	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		2278
1055	This benchmark atcually benchmarks the event loop itself. It works by	2279	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	2280	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	2281	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	2282	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	2283	watcher reads a byte it will write that byte to a random other "server".
1060		2284
1061	The effect is that there will be a lot of I/O watchers, only part of which	2285	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	2286	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	2287	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	2288	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	2289	most timeouts work (and puts extra pressure on the event loops).
1066		2290
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	2291	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	2292	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	2293	connections, most of which are idle at any one point in time.
1070		2294
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2295	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	2296	distribution. It uses the L<AE> interface, which makes a real difference
		2297	for the EV and Perl backends only.
1073		2298
1074	=head3 Explanation of the columns	2299	=head3 Explanation of the columns
1075		2300
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	2301	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	2302	each server has a read and write socket end).
1078		2303
1079	I<create> is the time it takes to create a socketpair (which is	2304	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	2305	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		2306
1082	I<request>, the most important value, is the time it takes to handle a	2307	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	2308	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	2309	it to another server. This includes deleting the old timeout and creating
1085	a new one that moves the timeout into the future.	2310	a new one that moves the timeout into the future.
1086		2311
1087	=head3 Results	2312	=head3 Results
1088		2313
1089	name sockets create request	2314	name sockets create request
1090	EV 20000 69.01 11.16	2315	EV 20000 62.66 7.99
1091	Perl 20000 75.28 112.76	2316	Perl 20000 68.32 32.64
1092	Event 20000 212.62 257.32	2317	IOAsync 20000 174.06 101.15 epoll
1093	Glib 20000 651.16 1896.30	2318	IOAsync 20000 174.67 610.84 poll
		2319	Event 20000 202.69 242.91
		2320	Glib 20000 557.01 1689.52
1094	POE 20000 349.67 12317.24 uses POE::Loop::Event	2321	POE 20000 341.54 12086.32 uses POE::Loop::Event
1095		2322
1096	=head3 Discussion	2323	=head3 Discussion
1097		2324
1098	This benchmark I<does> measure scalability and overall performance of the	2325	This benchmark I<does> measure scalability and overall performance of the
1099	particular event loop.	2326	particular event loop.
…		…
1101	EV is again fastest. Since it is using epoll on my system, the setup time	2328	EV is again fastest. Since it is using epoll on my system, the setup time
1102	is relatively high, though.	2329	is relatively high, though.
1103		2330
1104	Perl surprisingly comes second. It is much faster than the C-based event	2331	Perl surprisingly comes second. It is much faster than the C-based event
1105	loops Event and Glib.	2332	loops Event and Glib.
		2333
		2334	IO::Async performs very well when using its epoll backend, and still quite
		2335	good compared to Glib when using its pure perl backend.
1106		2336
1107	Event suffers from high setup time as well (look at its code and you will	2337	Event suffers from high setup time as well (look at its code and you will
1108	understand why). Callback invocation also has a high overhead compared to	2338	understand why). Callback invocation also has a high overhead compared to
1109	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2339	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1110	uses select or poll in basically all documented configurations.	2340	uses select or poll in basically all documented configurations.
…		…
1118		2348
1119	=head3 Summary	2349	=head3 Summary
1120		2350
1121	=over 4	2351	=over 4
1122		2352
1123	=item * The pure perl implementation performs extremely well, considering	2353	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		2354
1126	=item * Avoid Glib or POE in large projects where performance matters.	2355	=item * Avoid Glib or POE in large projects where performance matters.
1127		2356
1128	=back	2357	=back
1129		2358
…		…
1142		2371
1143	=head3 Results	2372	=head3 Results
1144		2373
1145	name sockets create request	2374	name sockets create request
1146	EV 16 20.00 6.54	2375	EV 16 20.00 6.54
		2376	Perl 16 25.75 12.62
1147	Event 16 81.27 35.86	2377	Event 16 81.27 35.86
1148	Glib 16 32.63 15.48	2378	Glib 16 32.63 15.48
1149	Perl 16 24.62 162.37
1150	POE 16 261.87 276.28 uses POE::Loop::Event	2379	POE 16 261.87 276.28 uses POE::Loop::Event
1151		2380
1152	=head3 Discussion	2381	=head3 Discussion
1153		2382
1154	The benchmark tries to test the performance of a typical small	2383	The benchmark tries to test the performance of a typical small
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	2387	speed most when you have lots of watchers, not when you only have a few of
1159	them).	2388	them).
1160		2389
1161	EV is again fastest.	2390	EV is again fastest.
1162		2391
1163	The C-based event loops Event and Glib come in second this time, as the	2392	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	2393	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	2394	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		2395
1170	POE also performs much better in this case, but is is still far behind the	2396	POE also performs much better in this case, but is is still far behind the
1171	others.	2397	others.
1172		2398
1173	=head3 Summary	2399	=head3 Summary
…		…
1177	=item * C-based event loops perform very well with small number of	2403	=item * C-based event loops perform very well with small number of
1178	watchers, as the management overhead dominates.	2404	watchers, as the management overhead dominates.
1179		2405
1180	=back	2406	=back
1181		2407
		2408	=head2 THE IO::Lambda BENCHMARK
		2409
		2410	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2411	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2412	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2413	shouldn't come as a surprise to anybody). As such, the benchmark is
		2414	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2415	very optimal. But how would AnyEvent compare when used without the extra
		2416	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2417
		2418	The benchmark itself creates an echo-server, and then, for 500 times,
		2419	connects to the echo server, sends a line, waits for the reply, and then
		2420	creates the next connection. This is a rather bad benchmark, as it doesn't
		2421	test the efficiency of the framework or much non-blocking I/O, but it is a
		2422	benchmark nevertheless.
		2423
		2424	name runtime
		2425	Lambda/select 0.330 sec
		2426	+ optimized 0.122 sec
		2427	Lambda/AnyEvent 0.327 sec
		2428	+ optimized 0.138 sec
		2429	Raw sockets/select 0.077 sec
		2430	POE/select, components 0.662 sec
		2431	POE/select, raw sockets 0.226 sec
		2432	POE/select, optimized 0.404 sec
		2433
		2434	AnyEvent/select/nb 0.085 sec
		2435	AnyEvent/EV/nb 0.068 sec
		2436	+state machine 0.134 sec
		2437
		2438	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2439	benchmarks actually make blocking connects and use 100% blocking I/O,
		2440	defeating the purpose of an event-based solution. All of the newly
		2441	written AnyEvent benchmarks use 100% non-blocking connects (using
		2442	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2443	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2444	generally require a lot more bookkeeping and event handling than blocking
		2445	connects (which involve a single syscall only).
		2446
		2447	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2448	offers similar expressive power as POE and IO::Lambda, using conventional
		2449	Perl syntax. This means that both the echo server and the client are 100%
		2450	non-blocking, further placing it at a disadvantage.
		2451
		2452	As you can see, the AnyEvent + EV combination even beats the
		2453	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2454	backend easily beats IO::Lambda and POE.
		2455
		2456	And even the 100% non-blocking version written using the high-level (and
		2457	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2458	higher level ("unoptimised") abstractions by a large margin, even though
		2459	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2460
		2461	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2462	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2463	part of the IO::Lambda distribution and were used without any changes.
		2464
		2465
		2466	=head1 SIGNALS
		2467
		2468	AnyEvent currently installs handlers for these signals:
		2469
		2470	=over 4
		2471
		2472	=item SIGCHLD
		2473
		2474	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2475	emulation for event loops that do not support them natively. Also, some
		2476	event loops install a similar handler.
		2477
		2478	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2479	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2480
		2481	=item SIGPIPE
		2482
		2483	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2484	when AnyEvent gets loaded.
		2485
		2486	The rationale for this is that AnyEvent users usually do not really depend
		2487	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2488	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2489	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2490	some random socket.
		2491
		2492	The rationale for installing a no-op handler as opposed to ignoring it is
		2493	that this way, the handler will be restored to defaults on exec.
		2494
		2495	Feel free to install your own handler, or reset it to defaults.
		2496
		2497	=back
		2498
		2499	=cut
		2500
		2501	undef $SIG{CHLD}
		2502	if $SIG{CHLD} eq 'IGNORE';
		2503
		2504	$SIG{PIPE} = sub { }
		2505	unless defined $SIG{PIPE};
		2506
		2507	=head1 RECOMMENDED/OPTIONAL MODULES
		2508
		2509	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2510	it's built-in modules) are required to use it.
		2511
		2512	That does not mean that AnyEvent won't take advantage of some additional
		2513	modules if they are installed.
		2514
		2515	This section explains which additional modules will be used, and how they
		2516	affect AnyEvent's operation.
		2517
		2518	=over 4
		2519
		2520	=item L<Async::Interrupt>
		2521
		2522	This slightly arcane module is used to implement fast signal handling: To
		2523	my knowledge, there is no way to do completely race-free and quick
		2524	signal handling in pure perl. To ensure that signals still get
		2525	delivered, AnyEvent will start an interval timer to wake up perl (and
		2526	catch the signals) with some delay (default is 10 seconds, look for
		2527	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2528
		2529	If this module is available, then it will be used to implement signal
		2530	catching, which means that signals will not be delayed, and the event loop
		2531	will not be interrupted regularly, which is more efficient (and good for
		2532	battery life on laptops).
		2533
		2534	This affects not just the pure-perl event loop, but also other event loops
		2535	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2536
		2537	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2538	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2539	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2540	does nothing for those backends.
		2541
		2542	=item L<EV>
		2543
		2544	This module isn't really "optional", as it is simply one of the backend
		2545	event loops that AnyEvent can use. However, it is simply the best event
		2546	loop available in terms of features, speed and stability: It supports
		2547	the AnyEvent API optimally, implements all the watcher types in XS, does
		2548	automatic timer adjustments even when no monotonic clock is available,
		2549	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2550	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2551	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2552
		2553	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2554	then this module will do nothing for you.
		2555
		2556	=item L<Guard>
		2557
		2558	The guard module, when used, will be used to implement
		2559	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2560	lot less memory), but otherwise doesn't affect guard operation much. It is
		2561	purely used for performance.
		2562
		2563	=item L<JSON> and L<JSON::XS>
		2564
		2565	One of these modules is required when you want to read or write JSON data
		2566	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2567	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2568
		2569	=item L<Net::SSLeay>
		2570
		2571	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2572	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2573	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2574
		2575	=item L<Time::HiRes>
		2576
		2577	This module is part of perl since release 5.008. It will be used when the
		2578	chosen event library does not come with a timing source on it's own. The
		2579	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2580	try to use a monotonic clock for timing stability.
		2581
		2582	=back
		2583
1182		2584
1183	=head1 FORK	2585	=head1 FORK
1184		2586
1185	Most event libraries are not fork-safe. The ones who are usually are	2587	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	2588	because they rely on inefficient but fork-safe C<select> or C<poll> calls
		2589	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2590	are usually badly thought-out hacks that are incompatible with fork in
		2591	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2592	continue event-processing in both parent and child (or both, if you know
		2593	what you are doing).
		2594
		2595	This means that, in general, you cannot fork and do event processing in
		2596	the child if the event library was initialised before the fork (which
		2597	usually happens when the first AnyEvent watcher is created, or the library
		2598	is loaded).
1187		2599
1188	If you have to fork, you must either do so I<before> creating your first	2600	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	2601	watcher OR you must not use AnyEvent at all in the child OR you must do
		2602	something completely out of the scope of AnyEvent.
		2603
		2604	The problem of doing event processing in the parent I<and> the child
		2605	is much more complicated: even for backends that I<are> fork-aware or
		2606	fork-safe, their behaviour is not usually what you want: fork clones all
		2607	watchers, that means all timers, I/O watchers etc. are active in both
		2608	parent and child, which is almost never what you want. USing C<exec>
		2609	to start worker children from some kind of manage rprocess is usually
		2610	preferred, because it is much easier and cleaner, at the expense of having
		2611	to have another binary.
1190		2612
1191		2613
1192	=head1 SECURITY CONSIDERATIONS	2614	=head1 SECURITY CONSIDERATIONS
1193		2615
1194	AnyEvent can be forced to load any event model via	2616	AnyEvent can be forced to load any event model via
…		…
1199	specified in the variable.	2621	specified in the variable.
1200		2622
1201	You can make AnyEvent completely ignore this variable by deleting it	2623	You can make AnyEvent completely ignore this variable by deleting it
1202	before the first watcher gets created, e.g. with a C<BEGIN> block:	2624	before the first watcher gets created, e.g. with a C<BEGIN> block:
1203		2625
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2626	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		2627
1206	use AnyEvent;	2628	use AnyEvent;
		2629
		2630	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2631	be used to probe what backend is used and gain other information (which is
		2632	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2633	$ENV{PERL_ANYEVENT_STRICT}.
		2634
		2635	Note that AnyEvent will remove I<all> environment variables starting with
		2636	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2637	enabled.
		2638
		2639
		2640	=head1 BUGS
		2641
		2642	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2643	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2644	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2645	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2646	pronounced).
1207		2647
1208		2648
1209	=head1 SEE ALSO	2649	=head1 SEE ALSO
1210		2650
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2651	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2652
		2653	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	2654	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		2655
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2656	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
		2657	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
		2658	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2659	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.
1219		2660
		2661	Non-blocking file handles, sockets, TCP clients and
		2662	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2663
		2664	Asynchronous DNS: L<AnyEvent::DNS>.
		2665
		2666	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2667	L<Coro::Event>,
		2668
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2669	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2670	L<AnyEvent::HTTP>.
1221		2671
1222		2672
1223	=head1 AUTHOR	2673	=head1 AUTHOR
1224		2674
1225	Marc Lehmann <schmorp@schmorp.de>	2675	Marc Lehmann <schmorp@schmorp.de>
1226	http://home.schmorp.de/	2676	http://home.schmorp.de/
1227		2677
1228	=cut	2678	=cut
1229		2679
1230	1	2680	1
1231		2681

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