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Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC vs.
Revision 1.243 by root, Fri Jul 17 23:12:20 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	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	55	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,	56	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,	57	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	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	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	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	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	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	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	69	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	70	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	71	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	72	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.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	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	77	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,	78	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	79	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	80	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	81	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).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	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	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	86	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	87	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	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	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	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
…		…
243	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
245	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
246		364
247	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
249		368
250	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	370	so programs overwriting those signals directly will likely not work
		371	correctly.
		372
		373	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not
		374	support attaching callbacks to signals, which is a pity, as you cannot do
		375	race-free signal handling in perl. AnyEvent will try to do it's best, but
		376	in some cases, signals will be delayed. The maximum time a signal might
		377	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		378	seconds). This variable can be changed only before the first signal
		379	watcher is created, and should be left alone otherwise. Higher values
		380	will cause fewer spurious wake-ups, which is better for power and CPU
		381	saving. All these problems can be avoided by installing the optional
		382	L<Async::Interrupt> module.
252		383
253	Example: exit on SIGINT	384	Example: exit on SIGINT
254		385
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	386	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		387
257	=head2 CHILD PROCESS WATCHERS	388	=head2 CHILD PROCESS WATCHERS
258		389
259	You can also watch on a child process exit and catch its exit status.	390	You can also watch on a child process exit and catch its exit status.
260		391
261	The child process is specified by the C<pid> argument (if set to C<0>, it	392	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	393	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	394	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	395	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	396
266	you I<can> rely on child watcher callback arguments.	397	The callback will be called with the pid and exit status (as returned by
		398	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		399	callback arguments.
		400
		401	This watcher type works by installing a signal handler for C<SIGCHLD>,
		402	and since it cannot be shared, nothing else should use SIGCHLD or reap
		403	random child processes (waiting for specific child processes, e.g. inside
		404	C<system>, is just fine).
267		405
268	There is a slight catch to child watchers, however: you usually start them	406	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	407	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	408	have exited already (and no SIGCHLD will be sent anymore).
271		409
272	Not all event models handle this correctly (POE doesn't), but even for	410	Not all event models handle this correctly (neither POE nor IO::Async do,
		411	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	412	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	413	the process exits (i.e. before you fork in the first place). AnyEvent's
		414	pure perl event loop handles all cases correctly regardless of when you
		415	start the watcher.
275		416
276	This means you cannot create a child watcher as the very first thing in an	417	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	418	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	419	watcher before you C<fork> the child (alternatively, you can call
		420	C<AnyEvent::detect>).
		421
		422	As most event loops do not support waiting for child events, they will be
		423	emulated by AnyEvent in most cases, in which the latency and race problems
		424	mentioned in the description of signal watchers apply.
279		425
280	Example: fork a process and wait for it	426	Example: fork a process and wait for it
281		427
282	my $done = AnyEvent->condvar;	428	my $done = AnyEvent->condvar;
283		429
284	my $pid = fork or exit 5;	430	my $pid = fork or exit 5;
285		431
286	my $w = AnyEvent->child (	432	my $w = AnyEvent->child (
287	pid => $pid,	433	pid => $pid,
288	cb => sub {	434	cb => sub {
289	my ($pid, $status) = @_;	435	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	436	warn "pid $pid exited with status $status";
291	$done->send;	437	$done->send;
292	},	438	},
293	);	439	);
294		440
295	# do something else, then wait for process exit	441	# do something else, then wait for process exit
296	$done->recv;	442	$done->recv;
		443
		444	=head2 IDLE WATCHERS
		445
		446	Sometimes there is a need to do something, but it is not so important
		447	to do it instantly, but only when there is nothing better to do. This
		448	"nothing better to do" is usually defined to be "no other events need
		449	attention by the event loop".
		450
		451	Idle watchers ideally get invoked when the event loop has nothing
		452	better to do, just before it would block the process to wait for new
		453	events. Instead of blocking, the idle watcher is invoked.
		454
		455	Most event loops unfortunately do not really support idle watchers (only
		456	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		457	will simply call the callback "from time to time".
		458
		459	Example: read lines from STDIN, but only process them when the
		460	program is otherwise idle:
		461
		462	my @lines; # read data
		463	my $idle_w;
		464	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		465	push @lines, scalar <STDIN>;
		466
		467	# start an idle watcher, if not already done
		468	$idle_w ||= AnyEvent->idle (cb => sub {
		469	# handle only one line, when there are lines left
		470	if (my $line = shift @lines) {
		471	print "handled when idle: $line";
		472	} else {
		473	# otherwise disable the idle watcher again
		474	undef $idle_w;
		475	}
		476	});
		477	});
297		478
298	=head2 CONDITION VARIABLES	479	=head2 CONDITION VARIABLES
299		480
300	If you are familiar with some event loops you will know that all of them	481	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	482	require you to run some blocking "loop", "run" or similar function that
302	will actively watch for new events and call your callbacks.	483	will actively watch for new events and call your callbacks.
303		484
304	AnyEvent is different, it expects somebody else to run the event loop and	485	AnyEvent is slightly different: it expects somebody else to run the event
305	will only block when necessary (usually when told by the user).	486	loop and will only block when necessary (usually when told by the user).
306		487
307	The instrument to do that is called a "condition variable", so called	488	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	489	because they represent a condition that must become true.
		490
		491	Now is probably a good time to look at the examples further below.
309		492
310	Condition variables can be created by calling the C<< AnyEvent->condvar	493	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	494	>> method, usually without arguments. The only argument pair allowed is
312	C<cb>, which specifies a callback to be called when the condition variable	495	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	496	becomes true, with the condition variable as the first argument (but not
		497	the results).
314		498
315	After creation, the condition variable is "false" until it becomes "true"	499	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	500	by calling the C<send> method (or calling the condition variable as if it
317	were a callback, read about the caveats in the description for the C<<	501	were a callback, read about the caveats in the description for the C<<
318	->send >> method).	502	->send >> method).
…		…
364	after => 1,	548	after => 1,
365	cb => sub { $result_ready->send },	549	cb => sub { $result_ready->send },
366	);	550	);
367		551
368	# this "blocks" (while handling events) till the callback	552	# this "blocks" (while handling events) till the callback
369	# calls send	553	# calls -<send
370	$result_ready->recv;	554	$result_ready->recv;
371		555
372	Example: wait for a timer, but take advantage of the fact that	556	Example: wait for a timer, but take advantage of the fact that condition
373	condition variables are also code references.	557	variables are also callable directly.
374		558
375	my $done = AnyEvent->condvar;	559	my $done = AnyEvent->condvar;
376	my $delay = AnyEvent->timer (after => 5, cb => $done);	560	my $delay = AnyEvent->timer (after => 5, cb => $done);
377	$done->recv;	561	$done->recv;
		562
		563	Example: Imagine an API that returns a condvar and doesn't support
		564	callbacks. This is how you make a synchronous call, for example from
		565	the main program:
		566
		567	use AnyEvent::CouchDB;
		568
		569	...
		570
		571	my @info = $couchdb->info->recv;
		572
		573	And this is how you would just set a callback to be called whenever the
		574	results are available:
		575
		576	$couchdb->info->cb (sub {
		577	my @info = $_[0]->recv;
		578	});
378		579
379	=head3 METHODS FOR PRODUCERS	580	=head3 METHODS FOR PRODUCERS
380		581
381	These methods should only be used by the producing side, i.e. the	582	These methods should only be used by the producing side, i.e. the
382	code/module that eventually sends the signal. Note that it is also	583	code/module that eventually sends the signal. Note that it is also
…		…
395	immediately from within send.	596	immediately from within send.
396		597
397	Any arguments passed to the C<send> call will be returned by all	598	Any arguments passed to the C<send> call will be returned by all
398	future C<< ->recv >> calls.	599	future C<< ->recv >> calls.
399		600
400	Condition variables are overloaded so one can call them directly	601	Condition variables are overloaded so one can call them directly (as if
401	(as a code reference). Calling them directly is the same as calling	602	they were a code reference). Calling them directly is the same as calling
402	C<send>. Note, however, that many C-based event loops do not handle	603	C<send>.
403	overloading, so as tempting as it may be, passing a condition variable
404	instead of a callback does not work. Both the pure perl and EV loops
405	support overloading, however, as well as all functions that use perl to
406	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407	example).
408		604
409	=item $cv->croak ($error)	605	=item $cv->croak ($error)
410		606
411	Similar to send, but causes all call's to C<< ->recv >> to invoke	607	Similar to send, but causes all call's to C<< ->recv >> to invoke
412	C<Carp::croak> with the given error message/object/scalar.	608	C<Carp::croak> with the given error message/object/scalar.
413		609
414	This can be used to signal any errors to the condition variable	610	This can be used to signal any errors to the condition variable
415	user/consumer.	611	user/consumer. Doing it this way instead of calling C<croak> directly
		612	delays the error detetcion, but has the overwhelmign advantage that it
		613	diagnoses the error at the place where the result is expected, and not
		614	deep in some event clalback without connection to the actual code causing
		615	the problem.
416		616
417	=item $cv->begin ([group callback])	617	=item $cv->begin ([group callback])
418		618
419	=item $cv->end	619	=item $cv->end
420
421	These two methods are EXPERIMENTAL and MIGHT CHANGE.
422		620
423	These two methods can be used to combine many transactions/events into	621	These two methods can be used to combine many transactions/events into
424	one. For example, a function that pings many hosts in parallel might want	622	one. For example, a function that pings many hosts in parallel might want
425	to use a condition variable for the whole process.	623	to use a condition variable for the whole process.
426		624
…		…
428	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	626	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
429	>>, the (last) callback passed to C<begin> will be executed. That callback	627	>>, the (last) callback passed to C<begin> will be executed. That callback
430	is I<supposed> to call C<< ->send >>, but that is not required. If no	628	is I<supposed> to call C<< ->send >>, but that is not required. If no
431	callback was set, C<send> will be called without any arguments.	629	callback was set, C<send> will be called without any arguments.
432		630
433	Let's clarify this with the ping example:	631	You can think of C<< $cv->send >> giving you an OR condition (one call
		632	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		633	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		634
		635	Let's start with a simple example: you have two I/O watchers (for example,
		636	STDOUT and STDERR for a program), and you want to wait for both streams to
		637	close before activating a condvar:
		638
		639	my $cv = AnyEvent->condvar;
		640
		641	$cv->begin; # first watcher
		642	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		643	defined sysread $fh1, my $buf, 4096
		644	or $cv->end;
		645	});
		646
		647	$cv->begin; # second watcher
		648	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		649	defined sysread $fh2, my $buf, 4096
		650	or $cv->end;
		651	});
		652
		653	$cv->recv;
		654
		655	This works because for every event source (EOF on file handle), there is
		656	one call to C<begin>, so the condvar waits for all calls to C<end> before
		657	sending.
		658
		659	The ping example mentioned above is slightly more complicated, as the
		660	there are results to be passwd back, and the number of tasks that are
		661	begung can potentially be zero:
434		662
435	my $cv = AnyEvent->condvar;	663	my $cv = AnyEvent->condvar;
436		664
437	my %result;	665	my %result;
438	$cv->begin (sub { $cv->send (\%result) });	666	$cv->begin (sub { $cv->send (\%result) });
…		…
458	loop, which serves two important purposes: first, it sets the callback	686	loop, which serves two important purposes: first, it sets the callback
459	to be called once the counter reaches C<0>, and second, it ensures that	687	to be called once the counter reaches C<0>, and second, it ensures that
460	C<send> is called even when C<no> hosts are being pinged (the loop	688	C<send> is called even when C<no> hosts are being pinged (the loop
461	doesn't execute once).	689	doesn't execute once).
462		690
463	This is the general pattern when you "fan out" into multiple subrequests:	691	This is the general pattern when you "fan out" into multiple (but
464	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	692	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
465	is called at least once, and then, for each subrequest you start, call	693	the callback and ensure C<end> is called at least once, and then, for each
466	C<begin> and for each subrequest you finish, call C<end>.	694	subrequest you start, call C<begin> and for each subrequest you finish,
		695	call C<end>.
467		696
468	=back	697	=back
469		698
470	=head3 METHODS FOR CONSUMERS	699	=head3 METHODS FOR CONSUMERS
471		700
…		…
487	function will call C<croak>.	716	function will call C<croak>.
488		717
489	In list context, all parameters passed to C<send> will be returned,	718	In list context, all parameters passed to C<send> will be returned,
490	in scalar context only the first one will be returned.	719	in scalar context only the first one will be returned.
491		720
		721	Note that doing a blocking wait in a callback is not supported by any
		722	event loop, that is, recursive invocation of a blocking C<< ->recv
		723	>> is not allowed, and the C<recv> call will C<croak> if such a
		724	condition is detected. This condition can be slightly loosened by using
		725	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		726	any thread that doesn't run the event loop itself.
		727
492	Not all event models support a blocking wait - some die in that case	728	Not all event models support a blocking wait - some die in that case
493	(programs might want to do that to stay interactive), so I<if you are	729	(programs might want to do that to stay interactive), so I<if you are
494	using this from a module, never require a blocking wait>, but let the	730	using this from a module, never require a blocking wait>. Instead, let the
495	caller decide whether the call will block or not (for example, by coupling	731	caller decide whether the call will block or not (for example, by coupling
496	condition variables with some kind of request results and supporting	732	condition variables with some kind of request results and supporting
497	callbacks so the caller knows that getting the result will not block,	733	callbacks so the caller knows that getting the result will not block,
498	while still supporting blocking waits if the caller so desires).	734	while still supporting blocking waits if the caller so desires).
499		735
500	Another reason I<never> to C<< ->recv >> in a module is that you cannot
501	sensibly have two C<< ->recv >>'s in parallel, as that would require
502	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
503	can supply.
504
505	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
506	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
507	versions and also integrates coroutines into AnyEvent, making blocking
508	C<< ->recv >> calls perfectly safe as long as they are done from another
509	coroutine (one that doesn't run the event loop).
510
511	You can ensure that C<< -recv >> never blocks by setting a callback and	736	You can ensure that C<< -recv >> never blocks by setting a callback and
512	only calling C<< ->recv >> from within that callback (or at a later	737	only calling C<< ->recv >> from within that callback (or at a later
513	time). This will work even when the event loop does not support blocking	738	time). This will work even when the event loop does not support blocking
514	waits otherwise.	739	waits otherwise.
515		740
516	=item $bool = $cv->ready	741	=item $bool = $cv->ready
517		742
518	Returns true when the condition is "true", i.e. whether C<send> or	743	Returns true when the condition is "true", i.e. whether C<send> or
519	C<croak> have been called.	744	C<croak> have been called.
520		745
521	=item $cb = $cv->cb ([new callback])	746	=item $cb = $cv->cb ($cb->($cv))
522		747
523	This is a mutator function that returns the callback set and optionally	748	This is a mutator function that returns the callback set and optionally
524	replaces it before doing so.	749	replaces it before doing so.
525		750
526	The callback will be called when the condition becomes "true", i.e. when	751	The callback will be called when the condition becomes "true", i.e. when
527	C<send> or C<croak> are called. Calling C<recv> inside the callback	752	C<send> or C<croak> are called, with the only argument being the condition
528	or at any later time is guaranteed not to block.	753	variable itself. Calling C<recv> inside the callback or at any later time
		754	is guaranteed not to block.
529		755
530	=back	756	=back
531		757
		758	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		759
		760	The available backend classes are (every class has its own manpage):
		761
		762	=over 4
		763
		764	=item Backends that are autoprobed when no other event loop can be found.
		765
		766	EV is the preferred backend when no other event loop seems to be in
		767	use. If EV is not installed, then AnyEvent will try Event, and, failing
		768	that, will fall back to its own pure-perl implementation, which is
		769	available everywhere as it comes with AnyEvent itself.
		770
		771	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		772	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		773	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		774
		775	=item Backends that are transparently being picked up when they are used.
		776
		777	These will be used when they are currently loaded when the first watcher
		778	is created, in which case it is assumed that the application is using
		779	them. This means that AnyEvent will automatically pick the right backend
		780	when the main program loads an event module before anything starts to
		781	create watchers. Nothing special needs to be done by the main program.
		782
		783	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		784	AnyEvent::Impl::Tk based on Tk, very broken.
		785	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		786	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		787
		788	=item Backends with special needs.
		789
		790	Qt requires the Qt::Application to be instantiated first, but will
		791	otherwise be picked up automatically. As long as the main program
		792	instantiates the application before any AnyEvent watchers are created,
		793	everything should just work.
		794
		795	AnyEvent::Impl::Qt based on Qt.
		796
		797	Support for IO::Async can only be partial, as it is too broken and
		798	architecturally limited to even support the AnyEvent API. It also
		799	is the only event loop that needs the loop to be set explicitly, so
		800	it can only be used by a main program knowing about AnyEvent. See
		801	L<AnyEvent::Impl::Async> for the gory details.
		802
		803	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		804
		805	=item Event loops that are indirectly supported via other backends.
		806
		807	Some event loops can be supported via other modules:
		808
		809	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		810
		811	B<WxWidgets> has no support for watching file handles. However, you can
		812	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		813	polls 20 times per second, which was considered to be too horrible to even
		814	consider for AnyEvent.
		815
		816	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		817	backend, so it can be supported through POE.
		818
		819	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		820	load L<POE> when detecting them, in the hope that POE will pick them up,
		821	in which case everything will be automatic.
		822
		823	=back
		824
532	=head1 GLOBAL VARIABLES AND FUNCTIONS	825	=head1 GLOBAL VARIABLES AND FUNCTIONS
533		826
		827	These are not normally required to use AnyEvent, but can be useful to
		828	write AnyEvent extension modules.
		829
534	=over 4	830	=over 4
535		831
536	=item $AnyEvent::MODEL	832	=item $AnyEvent::MODEL
537		833
538	Contains C<undef> until the first watcher is being created. Then it	834	Contains C<undef> until the first watcher is being created, before the
		835	backend has been autodetected.
		836
539	contains the event model that is being used, which is the name of the	837	Afterwards it contains the event model that is being used, which is the
540	Perl class implementing the model. This class is usually one of the	838	name of the Perl class implementing the model. This class is usually one
541	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
542	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
543		841	will be C<urxvt::anyevent>).
544	The known classes so far are:
545
546	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
547	AnyEvent::Impl::Event based on Event, second best choice.
548	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
549	AnyEvent::Impl::Glib based on Glib, third-best choice.
550	AnyEvent::Impl::Tk based on Tk, very bad choice.
551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
553	AnyEvent::Impl::POE based on POE, not generic enough for full support.
554
555	There is no support for WxWidgets, as WxWidgets has no support for
556	watching file handles. However, you can use WxWidgets through the
557	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
558	second, which was considered to be too horrible to even consider for
559	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
560	it's adaptor.
561
562	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
563	autodetecting them.
564		842
565	=item AnyEvent::detect	843	=item AnyEvent::detect
566		844
567	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
568	if necessary. You should only call this function right before you would	846	if necessary. You should only call this function right before you would
569	have created an AnyEvent watcher anyway, that is, as late as possible at	847	have created an AnyEvent watcher anyway, that is, as late as possible at
570	runtime.	848	runtime, and not e.g. while initialising of your module.
		849
		850	If you need to do some initialisation before AnyEvent watchers are
		851	created, use C<post_detect>.
571		852
572	=item $guard = AnyEvent::post_detect { BLOCK }	853	=item $guard = AnyEvent::post_detect { BLOCK }
573		854
574	Arranges for the code block to be executed as soon as the event model is	855	Arranges for the code block to be executed as soon as the event model is
575	autodetected (or immediately if this has already happened).	856	autodetected (or immediately if this has already happened).
		857
		858	The block will be executed I<after> the actual backend has been detected
		859	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		860	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		861	other initialisations - see the sources of L<AnyEvent::Strict> or
		862	L<AnyEvent::AIO> to see how this is used.
		863
		864	The most common usage is to create some global watchers, without forcing
		865	event module detection too early, for example, L<AnyEvent::AIO> creates
		866	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		867	avoid autodetecting the event module at load time.
576		868
577	If called in scalar or list context, then it creates and returns an object	869	If called in scalar or list context, then it creates and returns an object
578	that automatically removes the callback again when it is destroyed. See	870	that automatically removes the callback again when it is destroyed. See
579	L<Coro::BDB> for a case where this is useful.	871	L<Coro::BDB> for a case where this is useful.
580		872
…		…
583	If there are any code references in this array (you can C<push> to it	875	If there are any code references in this array (you can C<push> to it
584	before or after loading AnyEvent), then they will called directly after	876	before or after loading AnyEvent), then they will called directly after
585	the event loop has been chosen.	877	the event loop has been chosen.
586		878
587	You should check C<$AnyEvent::MODEL> before adding to this array, though:	879	You should check C<$AnyEvent::MODEL> before adding to this array, though:
588	if it contains a true value then the event loop has already been detected,	880	if it is defined then the event loop has already been detected, and the
589	and the array will be ignored.	881	array will be ignored.
590		882
591	Best use C<AnyEvent::post_detect { BLOCK }> instead.	883	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		884	it,as it takes care of these details.
		885
		886	This variable is mainly useful for modules that can do something useful
		887	when AnyEvent is used and thus want to know when it is initialised, but do
		888	not need to even load it by default. This array provides the means to hook
		889	into AnyEvent passively, without loading it.
592		890
593	=back	891	=back
594		892
595	=head1 WHAT TO DO IN A MODULE	893	=head1 WHAT TO DO IN A MODULE
596		894
…		…
651		949
652		950
653	=head1 OTHER MODULES	951	=head1 OTHER MODULES
654		952
655	The following is a non-exhaustive list of additional modules that use	953	The following is a non-exhaustive list of additional modules that use
656	AnyEvent and can therefore be mixed easily with other AnyEvent modules	954	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
657	in the same program. Some of the modules come with AnyEvent, some are	955	modules and other event loops in the same program. Some of the modules
658	available via CPAN.	956	come with AnyEvent, most are available via CPAN.
659		957
660	=over 4	958	=over 4
661		959
662	=item L<AnyEvent::Util>	960	=item L<AnyEvent::Util>
663		961
664	Contains various utility functions that replace often-used but blocking	962	Contains various utility functions that replace often-used but blocking
665	functions such as C<inet_aton> by event-/callback-based versions.	963	functions such as C<inet_aton> by event-/callback-based versions.
666
667	=item L<AnyEvent::Handle>
668
669	Provide read and write buffers and manages watchers for reads and writes.
670		964
671	=item L<AnyEvent::Socket>	965	=item L<AnyEvent::Socket>
672		966
673	Provides various utility functions for (internet protocol) sockets,	967	Provides various utility functions for (internet protocol) sockets,
674	addresses and name resolution. Also functions to create non-blocking tcp	968	addresses and name resolution. Also functions to create non-blocking tcp
675	connections or tcp servers, with IPv6 and SRV record support and more.	969	connections or tcp servers, with IPv6 and SRV record support and more.
676		970
		971	=item L<AnyEvent::Handle>
		972
		973	Provide read and write buffers, manages watchers for reads and writes,
		974	supports raw and formatted I/O, I/O queued and fully transparent and
		975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		976
677	=item L<AnyEvent::DNS>	977	=item L<AnyEvent::DNS>
678		978
679	Provides rich asynchronous DNS resolver capabilities.	979	Provides rich asynchronous DNS resolver capabilities.
680		980
		981	=item L<AnyEvent::HTTP>
		982
		983	A simple-to-use HTTP library that is capable of making a lot of concurrent
		984	HTTP requests.
		985
681	=item L<AnyEvent::HTTPD>	986	=item L<AnyEvent::HTTPD>
682		987
683	Provides a simple web application server framework.	988	Provides a simple web application server framework.
684		989
685	=item L<AnyEvent::FastPing>	990	=item L<AnyEvent::FastPing>
686		991
687	The fastest ping in the west.	992	The fastest ping in the west.
688		993
		994	=item L<AnyEvent::DBI>
		995
		996	Executes L<DBI> requests asynchronously in a proxy process.
		997
		998	=item L<AnyEvent::AIO>
		999
		1000	Truly asynchronous I/O, should be in the toolbox of every event
		1001	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1002	together.
		1003
		1004	=item L<AnyEvent::BDB>
		1005
		1006	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1007	L<BDB> and AnyEvent together.
		1008
		1009	=item L<AnyEvent::GPSD>
		1010
		1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1012
689	=item L<Net::IRC3>	1013	=item L<AnyEvent::IRC>
690		1014
691	AnyEvent based IRC client module family.	1015	AnyEvent based IRC client module family (replacing the older Net::IRC3).
692		1016
693	=item L<Net::XMPP2>	1017	=item L<AnyEvent::XMPP>
694		1018
695	AnyEvent based XMPP (Jabber protocol) module family.	1019	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1020	Net::XMPP2>.
		1021
		1022	=item L<AnyEvent::IGS>
		1023
		1024	A non-blocking interface to the Internet Go Server protocol (used by
		1025	L<App::IGS>).
696		1026
697	=item L<Net::FCP>	1027	=item L<Net::FCP>
698		1028
699	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
700	of AnyEvent.	1030	of AnyEvent.
…		…
705		1035
706	=item L<Coro>	1036	=item L<Coro>
707		1037
708	Has special support for AnyEvent via L<Coro::AnyEvent>.	1038	Has special support for AnyEvent via L<Coro::AnyEvent>.
709		1039
710	=item L<AnyEvent::AIO>, L<IO::AIO>
711
712	Truly asynchronous I/O, should be in the toolbox of every event
713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714	together.
715
716	=item L<AnyEvent::BDB>, L<BDB>
717
718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719	IO::AIO and AnyEvent together.
720
721	=item L<IO::Lambda>
722
723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724
725	=back	1040	=back
726		1041
727	=cut	1042	=cut
728		1043
729	package AnyEvent;	1044	package AnyEvent;
730		1045
		1046	# basically a tuned-down version of common::sense
		1047	sub common_sense {
731	no warnings;	1048	# no warnings
732	use strict;	1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1050	# use strict vars subs
		1051	$^H |= 0x00000600;
		1052	}
733		1053
		1054	BEGIN { AnyEvent::common_sense }
		1055
734	use Carp;	1056	use Carp ();
735		1057
736	our $VERSION = '4.03';	1058	our $VERSION = 4.83;
737	our $MODEL;	1059	our $MODEL;
738		1060
739	our $AUTOLOAD;	1061	our $AUTOLOAD;
740	our @ISA;	1062	our @ISA;
741		1063
742	our @REGISTRY;	1064	our @REGISTRY;
743		1065
		1066	our $WIN32;
		1067
		1068	our $VERBOSE;
		1069
		1070	BEGIN {
		1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1073
		1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1075	if ${^TAINT};
		1076
744	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1078
		1079	}
		1080
		1081	our $MAX_SIGNAL_LATENCY = 10;
745		1082
746	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
747		1084
748	{	1085	{
749	my $idx;	1086	my $idx;
…		…
757	[Event:: => AnyEvent::Impl::Event::],	1094	[Event:: => AnyEvent::Impl::Event::],
758	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
759	# everything below here will not be autoprobed	1096	# everything below here will not be autoprobed
760	# as the pureperl backend should work everywhere	1097	# as the pureperl backend should work everywhere
761	# and is usually faster	1098	# and is usually faster
762	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
763	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
764	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
765	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
766	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767	[Wx:: => AnyEvent::Impl::POE::],	1104	[Wx:: => AnyEvent::Impl::POE::],
768	[Prima:: => AnyEvent::Impl::POE::],	1105	[Prima:: => AnyEvent::Impl::POE::],
		1106	# IO::Async is just too broken - we would need workarounds for its
		1107	# byzantine signal and broken child handling, among others.
		1108	# IO::Async is rather hard to detect, as it doesn't have any
		1109	# obvious default class.
		1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
769	);	1113	);
770		1114
771	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1115	our %method = map +($_ => 1),
		1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
772		1117
773	our @post_detect;	1118	our @post_detect;
774		1119
775	sub post_detect(&) {	1120	sub post_detect(&) {
776	my ($cb) = @_;	1121	my ($cb) = @_;
…		…
781	1	1126	1
782	} else {	1127	} else {
783	push @post_detect, $cb;	1128	push @post_detect, $cb;
784		1129
785	defined wantarray	1130	defined wantarray
786	? bless \$cb, "AnyEvent::Util::PostDetect"	1131	? bless \$cb, "AnyEvent::Util::postdetect"
787	: ()	1132	: ()
788	}	1133	}
789	}	1134	}
790		1135
791	sub AnyEvent::Util::PostDetect::DESTROY {	1136	sub AnyEvent::Util::postdetect::DESTROY {
792	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
793	}	1138	}
794		1139
795	sub detect() {	1140	sub detect() {
796	unless ($MODEL) {	1141	unless ($MODEL) {
797	no strict 'refs';
798	local $SIG{__DIE__};	1142	local $SIG{__DIE__};
799		1143
800	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
801	my $model = "AnyEvent::Impl::$1";	1145	my $model = "AnyEvent::Impl::$1";
802	if (eval "require $model") {	1146	if (eval "require $model") {
803	$MODEL = $model;	1147	$MODEL = $model;
804	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1148	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
805	} else {	1149	} else {
806	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
807	}	1151	}
808	}	1152	}
809		1153
810	# check for already loaded models	1154	# check for already loaded models
811	unless ($MODEL) {	1155	unless ($MODEL) {
812	for (@REGISTRY, @models) {	1156	for (@REGISTRY, @models) {
813	my ($package, $model) = @$_;	1157	my ($package, $model) = @$_;
814	if (${"$package\::VERSION"} > 0) {	1158	if (${"$package\::VERSION"} > 0) {
815	if (eval "require $model") {	1159	if (eval "require $model") {
816	$MODEL = $model;	1160	$MODEL = $model;
817	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
818	last;	1162	last;
819	}	1163	}
820	}	1164	}
821	}	1165	}
822		1166
…		…
827	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
828	if (eval "require $package"	1172	if (eval "require $package"
829	and ${"$package\::VERSION"} > 0	1173	and ${"$package\::VERSION"} > 0
830	and eval "require $model") {	1174	and eval "require $model") {
831	$MODEL = $model;	1175	$MODEL = $model;
832	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
833	last;	1177	last;
834	}	1178	}
835	}	1179	}
836		1180
837	$MODEL	1181	$MODEL
838	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
839	}	1183	}
840	}	1184	}
841		1185
		1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1187
842	unshift @ISA, $MODEL;	1188	unshift @ISA, $MODEL;
843	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1189
		1190	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
844		1191
845	(shift @post_detect)->() while @post_detect;	1192	(shift @post_detect)->() while @post_detect;
846	}	1193	}
847		1194
848	$MODEL	1195	$MODEL
…		…
850		1197
851	sub AUTOLOAD {	1198	sub AUTOLOAD {
852	(my $func = $AUTOLOAD) =~ s/.*://;	1199	(my $func = $AUTOLOAD) =~ s/.*://;
853		1200
854	$method{$func}	1201	$method{$func}
855	or croak "$func: not a valid method for AnyEvent objects";	1202	or Carp::croak "$func: not a valid method for AnyEvent objects";
856		1203
857	detect unless $MODEL;	1204	detect unless $MODEL;
858		1205
859	my $class = shift;	1206	my $class = shift;
860	$class->$func (@_);	1207	$class->$func (@_);
861	}	1208	}
862		1209
		1210	# utility function to dup a filehandle. this is used by many backends
		1211	# to support binding more than one watcher per filehandle (they usually
		1212	# allow only one watcher per fd, so we dup it to get a different one).
		1213	sub _dupfh($$;$$) {
		1214	my ($poll, $fh, $r, $w) = @_;
		1215
		1216	# cygwin requires the fh mode to be matching, unix doesn't
		1217	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1218
		1219	open my $fh2, $mode, $fh
		1220	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1221
		1222	# we assume CLOEXEC is already set by perl in all important cases
		1223
		1224	($fh2, $rw)
		1225	}
		1226
863	package AnyEvent::Base;	1227	package AnyEvent::Base;
864		1228
		1229	# default implementations for many methods
		1230
		1231	sub _time {
		1232	# probe for availability of Time::HiRes
		1233	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1234	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1235	*_time = \&Time::HiRes::time;
		1236	# if (eval "use POSIX (); (POSIX::times())...
		1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1239	*_time = sub { time }; # epic fail
		1240	}
		1241
		1242	&_time
		1243	}
		1244
		1245	sub time { _time }
		1246	sub now { _time }
		1247	sub now_update { }
		1248
865	# default implementation for ->condvar	1249	# default implementation for ->condvar
866		1250
867	sub condvar {	1251	sub condvar {
868	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
869	}	1253	}
870		1254
871	# default implementation for ->signal	1255	# default implementation for ->signal
872		1256
873	our %SIG_CB;	1257	our $HAVE_ASYNC_INTERRUPT;
		1258	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1259	our (%SIG_ASY, %SIG_ASY_W);
		1260	our ($SIG_COUNT, $SIG_TW);
874		1261
		1262	sub _signal_exec {
		1263	$HAVE_ASYNC_INTERRUPT
		1264	? $SIGPIPE_R->drain
		1265	: sysread $SIGPIPE_R, my $dummy, 9;
		1266
		1267	while (%SIG_EV) {
		1268	for (keys %SIG_EV) {
		1269	delete $SIG_EV{$_};
		1270	$_->() for values %{ $SIG_CB{$_} || {} };
		1271	}
		1272	}
		1273	}
		1274
875	sub signal {	1275	sub _signal {
876	my (undef, %arg) = @_;	1276	my (undef, %arg) = @_;
877		1277
878	my $signal = uc $arg{signal}	1278	my $signal = uc $arg{signal}
879	or Carp::croak "required option 'signal' is missing";	1279	or Carp::croak "required option 'signal' is missing";
880		1280
881	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1281	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1282
		1283	if ($HAVE_ASYNC_INTERRUPT) {
		1284	# async::interrupt
		1285
		1286	$SIG_ASY{$signal} ||= do {
		1287	my $asy = new Async::Interrupt
		1288	cb => sub { undef $SIG_EV{$signal} },
		1289	signal => $signal,
		1290	pipe => [$SIGPIPE_R->filenos],
		1291	;
		1292	$asy->pipe_autodrain (0);
		1293
		1294	$asy
		1295	};
		1296
		1297	} else {
		1298	# pure perl
		1299
882	$SIG{$signal} ||= sub {	1300	$SIG{$signal} ||= sub {
883	$_->() for values %{ $SIG_CB{$signal} || {} };	1301	local $!;
		1302	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1303	undef $SIG_EV{$signal};
		1304	};
		1305
		1306	# can't do signal processing without introducing races in pure perl,
		1307	# so limit the signal latency.
		1308	++$SIG_COUNT;
		1309	$SIG_TW ||= AnyEvent->timer (
		1310	after => $MAX_SIGNAL_LATENCY,
		1311	interval => $MAX_SIGNAL_LATENCY,
		1312	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1313	);
884	};	1314	}
885		1315
886	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1316	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
887	}	1317	}
888		1318
		1319	sub signal {
		1320	# probe for availability of Async::Interrupt
		1321	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1322	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1323
		1324	$HAVE_ASYNC_INTERRUPT = 1;
		1325	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1326	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1327
		1328	} else {
		1329	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1330
		1331	require Fcntl;
		1332
		1333	if (AnyEvent::WIN32) {
		1334	require AnyEvent::Util;
		1335
		1336	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1337	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1338	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1339	} else {
		1340	pipe $SIGPIPE_R, $SIGPIPE_W;
		1341	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1342	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1343
		1344	# not strictly required, as $^F is normally 2, but let's make sure...
		1345	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1346	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1347	}
		1348
		1349	$SIGPIPE_R
		1350	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1351
		1352	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1353	}
		1354
		1355	*signal = \&_signal;
		1356	&signal
		1357	}
		1358
889	sub AnyEvent::Base::Signal::DESTROY {	1359	sub AnyEvent::Base::signal::DESTROY {
890	my ($signal, $cb) = @{$_[0]};	1360	my ($signal, $cb) = @{$_[0]};
891		1361
		1362	undef $SIG_TW
		1363	unless --$SIG_COUNT;
		1364
892	delete $SIG_CB{$signal}{$cb};	1365	delete $SIG_CB{$signal}{$cb};
893		1366
894	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1367	# delete doesn't work with older perls - they then
		1368	# print weird messages, or just unconditionally exit
		1369	# instead of getting the default action.
		1370	undef $SIG{$signal}
		1371	unless keys %{ $SIG_CB{$signal} };
895	}	1372	}
896		1373
897	# default implementation for ->child	1374	# default implementation for ->child
898		1375
899	our %PID_CB;	1376	our %PID_CB;
900	our $CHLD_W;	1377	our $CHLD_W;
901	our $CHLD_DELAY_W;	1378	our $CHLD_DELAY_W;
902	our $PID_IDLE;
903	our $WNOHANG;	1379	our $WNOHANG;
904		1380
905	sub _child_wait {	1381	sub _sigchld {
906	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1382	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1383	$_->($pid, $?)
907	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1384	for values %{ $PID_CB{$pid} || {} },
908	(values %{ $PID_CB{0} || {} });	1385	values %{ $PID_CB{0} || {} };
909	}	1386	}
910
911	undef $PID_IDLE;
912	}
913
914	sub _sigchld {
915	# make sure we deliver these changes "synchronous" with the event loop.
916	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
917	undef $CHLD_DELAY_W;
918	&_child_wait;
919	});
920	}	1387	}
921		1388
922	sub child {	1389	sub child {
923	my (undef, %arg) = @_;	1390	my (undef, %arg) = @_;
924		1391
925	defined (my $pid = $arg{pid} + 0)	1392	defined (my $pid = $arg{pid} + 0)
926	or Carp::croak "required option 'pid' is missing";	1393	or Carp::croak "required option 'pid' is missing";
927		1394
928	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1395	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
929		1396
930	unless ($WNOHANG) {	1397	# WNOHANG is almost cetrainly 1 everywhere
		1398	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1399	? 1
931	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1400	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
932	}
933		1401
934	unless ($CHLD_W) {	1402	unless ($CHLD_W) {
935	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
936	# child could be a zombie already, so make at least one round	1404	# child could be a zombie already, so make at least one round
937	&_sigchld;	1405	&_sigchld;
938	}	1406	}
939		1407
940	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1408	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
941	}	1409	}
942		1410
943	sub AnyEvent::Base::Child::DESTROY {	1411	sub AnyEvent::Base::child::DESTROY {
944	my ($pid, $cb) = @{$_[0]};	1412	my ($pid, $cb) = @{$_[0]};
945		1413
946	delete $PID_CB{$pid}{$cb};	1414	delete $PID_CB{$pid}{$cb};
947	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1415	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
948		1416
949	undef $CHLD_W unless keys %PID_CB;	1417	undef $CHLD_W unless keys %PID_CB;
950	}	1418	}
951		1419
		1420	# idle emulation is done by simply using a timer, regardless
		1421	# of whether the process is idle or not, and not letting
		1422	# the callback use more than 50% of the time.
		1423	sub idle {
		1424	my (undef, %arg) = @_;
		1425
		1426	my ($cb, $w, $rcb) = $arg{cb};
		1427
		1428	$rcb = sub {
		1429	if ($cb) {
		1430	$w = _time;
		1431	&$cb;
		1432	$w = _time - $w;
		1433
		1434	# never use more then 50% of the time for the idle watcher,
		1435	# within some limits
		1436	$w = 0.0001 if $w < 0.0001;
		1437	$w = 5 if $w > 5;
		1438
		1439	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1440	} else {
		1441	# clean up...
		1442	undef $w;
		1443	undef $rcb;
		1444	}
		1445	};
		1446
		1447	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1448
		1449	bless \\$cb, "AnyEvent::Base::idle"
		1450	}
		1451
		1452	sub AnyEvent::Base::idle::DESTROY {
		1453	undef $${$_[0]};
		1454	}
		1455
952	package AnyEvent::CondVar;	1456	package AnyEvent::CondVar;
953		1457
954	our @ISA = AnyEvent::CondVar::Base::;	1458	our @ISA = AnyEvent::CondVar::Base::;
955		1459
956	package AnyEvent::CondVar::Base;	1460	package AnyEvent::CondVar::Base;
957		1461
958	use overload	1462	#use overload
959	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1463	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
960	fallback => 1;	1464	# fallback => 1;
		1465
		1466	# save 300+ kilobytes by dirtily hardcoding overloading
		1467	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1468	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1469	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1470	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1471
		1472	our $WAITING;
961		1473
962	sub _send {	1474	sub _send {
963	# nop	1475	# nop
964	}	1476	}
965		1477
…		…
978	sub ready {	1490	sub ready {
979	$_[0]{_ae_sent}	1491	$_[0]{_ae_sent}
980	}	1492	}
981		1493
982	sub _wait {	1494	sub _wait {
		1495	$WAITING
		1496	and !$_[0]{_ae_sent}
		1497	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1498
		1499	local $WAITING = 1;
983	AnyEvent->one_event while !$_[0]{_ae_sent};	1500	AnyEvent->one_event while !$_[0]{_ae_sent};
984	}	1501	}
985		1502
986	sub recv {	1503	sub recv {
987	$_[0]->_wait;	1504	$_[0]->_wait;
…		…
1006	}	1523	}
1007		1524
1008	# undocumented/compatibility with pre-3.4	1525	# undocumented/compatibility with pre-3.4
1009	*broadcast = \&send;	1526	*broadcast = \&send;
1010	*wait = \&_wait;	1527	*wait = \&_wait;
		1528
		1529	=head1 ERROR AND EXCEPTION HANDLING
		1530
		1531	In general, AnyEvent does not do any error handling - it relies on the
		1532	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1533	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1534	checking of all AnyEvent methods, however, which is highly useful during
		1535	development.
		1536
		1537	As for exception handling (i.e. runtime errors and exceptions thrown while
		1538	executing a callback), this is not only highly event-loop specific, but
		1539	also not in any way wrapped by this module, as this is the job of the main
		1540	program.
		1541
		1542	The pure perl event loop simply re-throws the exception (usually
		1543	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1544	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1545	so on.
		1546
		1547	=head1 ENVIRONMENT VARIABLES
		1548
		1549	The following environment variables are used by this module or its
		1550	submodules.
		1551
		1552	Note that AnyEvent will remove I<all> environment variables starting with
		1553	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1554	enabled.
		1555
		1556	=over 4
		1557
		1558	=item C<PERL_ANYEVENT_VERBOSE>
		1559
		1560	By default, AnyEvent will be completely silent except in fatal
		1561	conditions. You can set this environment variable to make AnyEvent more
		1562	talkative.
		1563
		1564	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1565	conditions, such as not being able to load the event model specified by
		1566	C<PERL_ANYEVENT_MODEL>.
		1567
		1568	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1569	model it chooses.
		1570
		1571	=item C<PERL_ANYEVENT_STRICT>
		1572
		1573	AnyEvent does not do much argument checking by default, as thorough
		1574	argument checking is very costly. Setting this variable to a true value
		1575	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1576	check the arguments passed to most method calls. If it finds any problems,
		1577	it will croak.
		1578
		1579	In other words, enables "strict" mode.
		1580
		1581	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1582	>>, it is definitely recommended to keep it off in production. Keeping
		1583	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1584	can be very useful, however.
		1585
		1586	=item C<PERL_ANYEVENT_MODEL>
		1587
		1588	This can be used to specify the event model to be used by AnyEvent, before
		1589	auto detection and -probing kicks in. It must be a string consisting
		1590	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1591	and the resulting module name is loaded and if the load was successful,
		1592	used as event model. If it fails to load AnyEvent will proceed with
		1593	auto detection and -probing.
		1594
		1595	This functionality might change in future versions.
		1596
		1597	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1598	could start your program like this:
		1599
		1600	PERL_ANYEVENT_MODEL=Perl perl ...
		1601
		1602	=item C<PERL_ANYEVENT_PROTOCOLS>
		1603
		1604	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1605	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1606	of auto probing).
		1607
		1608	Must be set to a comma-separated list of protocols or address families,
		1609	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1610	used, and preference will be given to protocols mentioned earlier in the
		1611	list.
		1612
		1613	This variable can effectively be used for denial-of-service attacks
		1614	against local programs (e.g. when setuid), although the impact is likely
		1615	small, as the program has to handle conenction and other failures anyways.
		1616
		1617	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1618	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1619	- only support IPv4, never try to resolve or contact IPv6
		1620	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1621	IPv6, but prefer IPv6 over IPv4.
		1622
		1623	=item C<PERL_ANYEVENT_EDNS0>
		1624
		1625	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1626	for DNS. This extension is generally useful to reduce DNS traffic, but
		1627	some (broken) firewalls drop such DNS packets, which is why it is off by
		1628	default.
		1629
		1630	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1631	EDNS0 in its DNS requests.
		1632
		1633	=item C<PERL_ANYEVENT_MAX_FORKS>
		1634
		1635	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1636	will create in parallel.
		1637
		1638	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1639
		1640	The default value for the C<max_outstanding> parameter for the default DNS
		1641	resolver - this is the maximum number of parallel DNS requests that are
		1642	sent to the DNS server.
		1643
		1644	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1645
		1646	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1647	configuration) in the default resolver. When set to the empty string, no
		1648	default config will be used.
		1649
		1650	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1651
		1652	When neither C<ca_file> nor C<ca_path> was specified during
		1653	L<AnyEvent::TLS> context creation, and either of these environment
		1654	variables exist, they will be used to specify CA certificate locations
		1655	instead of a system-dependent default.
		1656
		1657	=back
1011		1658
1012	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1659	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1013		1660
1014	This is an advanced topic that you do not normally need to use AnyEvent in	1661	This is an advanced topic that you do not normally need to use AnyEvent in
1015	a module. This section is only of use to event loop authors who want to	1662	a module. This section is only of use to event loop authors who want to
…		…
1049		1696
1050	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1697	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1051	condition variables: code blocking while waiting for a condition will	1698	condition variables: code blocking while waiting for a condition will
1052	C<die>. This still works with most modules/usages, and blocking calls must	1699	C<die>. This still works with most modules/usages, and blocking calls must
1053	not be done in an interactive application, so it makes sense.	1700	not be done in an interactive application, so it makes sense.
1054
1055	=head1 ENVIRONMENT VARIABLES
1056
1057	The following environment variables are used by this module:
1058
1059	=over 4
1060
1061	=item C<PERL_ANYEVENT_VERBOSE>
1062
1063	By default, AnyEvent will be completely silent except in fatal
1064	conditions. You can set this environment variable to make AnyEvent more
1065	talkative.
1066
1067	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1068	conditions, such as not being able to load the event model specified by
1069	C<PERL_ANYEVENT_MODEL>.
1070
1071	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1072	model it chooses.
1073
1074	=item C<PERL_ANYEVENT_MODEL>
1075
1076	This can be used to specify the event model to be used by AnyEvent, before
1077	auto detection and -probing kicks in. It must be a string consisting
1078	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1079	and the resulting module name is loaded and if the load was successful,
1080	used as event model. If it fails to load AnyEvent will proceed with
1081	auto detection and -probing.
1082
1083	This functionality might change in future versions.
1084
1085	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1086	could start your program like this:
1087
1088	PERL_ANYEVENT_MODEL=Perl perl ...
1089
1090	=item C<PERL_ANYEVENT_PROTOCOLS>
1091
1092	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1093	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1094	of auto probing).
1095
1096	Must be set to a comma-separated list of protocols or address families,
1097	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1098	used, and preference will be given to protocols mentioned earlier in the
1099	list.
1100
1101	This variable can effectively be used for denial-of-service attacks
1102	against local programs (e.g. when setuid), although the impact is likely
1103	small, as the program has to handle connection errors already-
1104
1105	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1106	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1107	- only support IPv4, never try to resolve or contact IPv6
1108	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1109	IPv6, but prefer IPv6 over IPv4.
1110
1111	=item C<PERL_ANYEVENT_EDNS0>
1112
1113	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1114	for DNS. This extension is generally useful to reduce DNS traffic, but
1115	some (broken) firewalls drop such DNS packets, which is why it is off by
1116	default.
1117
1118	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1119	EDNS0 in its DNS requests.
1120
1121	=back
1122		1701
1123	=head1 EXAMPLE PROGRAM	1702	=head1 EXAMPLE PROGRAM
1124		1703
1125	The following program uses an I/O watcher to read data from STDIN, a timer	1704	The following program uses an I/O watcher to read data from STDIN, a timer
1126	to display a message once per second, and a condition variable to quit the	1705	to display a message once per second, and a condition variable to quit the
…		…
1320	watcher.	1899	watcher.
1321		1900
1322	=head3 Results	1901	=head3 Results
1323		1902
1324	name watchers bytes create invoke destroy comment	1903	name watchers bytes create invoke destroy comment
1325	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1904	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1326	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1905	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1327	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1906	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1328	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1907	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1329	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1908	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1330	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1909	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1910	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1911	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1331	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1912	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1332	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1913	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1333	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1914	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1334	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1915	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1335		1916
1336	=head3 Discussion	1917	=head3 Discussion
1337		1918
1338	The benchmark does I<not> measure scalability of the event loop very	1919	The benchmark does I<not> measure scalability of the event loop very
1339	well. For example, a select-based event loop (such as the pure perl one)	1920	well. For example, a select-based event loop (such as the pure perl one)
…		…
1364	performance becomes really bad with lots of file descriptors (and few of	1945	performance becomes really bad with lots of file descriptors (and few of
1365	them active), of course, but this was not subject of this benchmark.	1946	them active), of course, but this was not subject of this benchmark.
1366		1947
1367	The C<Event> module has a relatively high setup and callback invocation	1948	The C<Event> module has a relatively high setup and callback invocation
1368	cost, but overall scores in on the third place.	1949	cost, but overall scores in on the third place.
		1950
		1951	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1952	when using its pure perl backend.
1369		1953
1370	C<Glib>'s memory usage is quite a bit higher, but it features a	1954	C<Glib>'s memory usage is quite a bit higher, but it features a
1371	faster callback invocation and overall ends up in the same class as	1955	faster callback invocation and overall ends up in the same class as
1372	C<Event>. However, Glib scales extremely badly, doubling the number of	1956	C<Event>. However, Glib scales extremely badly, doubling the number of
1373	watchers increases the processing time by more than a factor of four,	1957	watchers increases the processing time by more than a factor of four,
…		…
1451	it to another server. This includes deleting the old timeout and creating	2035	it to another server. This includes deleting the old timeout and creating
1452	a new one that moves the timeout into the future.	2036	a new one that moves the timeout into the future.
1453		2037
1454	=head3 Results	2038	=head3 Results
1455		2039
1456	name sockets create request	2040	name sockets create request
1457	EV 20000 69.01 11.16	2041	EV 20000 69.01 11.16
1458	Perl 20000 73.32 35.87	2042	Perl 20000 73.32 35.87
		2043	IOAsync 20000 157.00 98.14 epoll
		2044	IOAsync 20000 159.31 616.06 poll
1459	Event 20000 212.62 257.32	2045	Event 20000 212.62 257.32
1460	Glib 20000 651.16 1896.30	2046	Glib 20000 651.16 1896.30
1461	POE 20000 349.67 12317.24 uses POE::Loop::Event	2047	POE 20000 349.67 12317.24 uses POE::Loop::Event
1462		2048
1463	=head3 Discussion	2049	=head3 Discussion
1464		2050
1465	This benchmark I<does> measure scalability and overall performance of the	2051	This benchmark I<does> measure scalability and overall performance of the
1466	particular event loop.	2052	particular event loop.
…		…
1468	EV is again fastest. Since it is using epoll on my system, the setup time	2054	EV is again fastest. Since it is using epoll on my system, the setup time
1469	is relatively high, though.	2055	is relatively high, though.
1470		2056
1471	Perl surprisingly comes second. It is much faster than the C-based event	2057	Perl surprisingly comes second. It is much faster than the C-based event
1472	loops Event and Glib.	2058	loops Event and Glib.
		2059
		2060	IO::Async performs very well when using its epoll backend, and still quite
		2061	good compared to Glib when using its pure perl backend.
1473		2062
1474	Event suffers from high setup time as well (look at its code and you will	2063	Event suffers from high setup time as well (look at its code and you will
1475	understand why). Callback invocation also has a high overhead compared to	2064	understand why). Callback invocation also has a high overhead compared to
1476	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2065	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1477	uses select or poll in basically all documented configurations.	2066	uses select or poll in basically all documented configurations.
…		…
1540	=item * C-based event loops perform very well with small number of	2129	=item * C-based event loops perform very well with small number of
1541	watchers, as the management overhead dominates.	2130	watchers, as the management overhead dominates.
1542		2131
1543	=back	2132	=back
1544		2133
		2134	=head2 THE IO::Lambda BENCHMARK
		2135
		2136	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2137	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2138	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2139	shouldn't come as a surprise to anybody). As such, the benchmark is
		2140	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2141	very optimal. But how would AnyEvent compare when used without the extra
		2142	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2143
		2144	The benchmark itself creates an echo-server, and then, for 500 times,
		2145	connects to the echo server, sends a line, waits for the reply, and then
		2146	creates the next connection. This is a rather bad benchmark, as it doesn't
		2147	test the efficiency of the framework or much non-blocking I/O, but it is a
		2148	benchmark nevertheless.
		2149
		2150	name runtime
		2151	Lambda/select 0.330 sec
		2152	+ optimized 0.122 sec
		2153	Lambda/AnyEvent 0.327 sec
		2154	+ optimized 0.138 sec
		2155	Raw sockets/select 0.077 sec
		2156	POE/select, components 0.662 sec
		2157	POE/select, raw sockets 0.226 sec
		2158	POE/select, optimized 0.404 sec
		2159
		2160	AnyEvent/select/nb 0.085 sec
		2161	AnyEvent/EV/nb 0.068 sec
		2162	+state machine 0.134 sec
		2163
		2164	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2165	benchmarks actually make blocking connects and use 100% blocking I/O,
		2166	defeating the purpose of an event-based solution. All of the newly
		2167	written AnyEvent benchmarks use 100% non-blocking connects (using
		2168	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2169	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2170	generally require a lot more bookkeeping and event handling than blocking
		2171	connects (which involve a single syscall only).
		2172
		2173	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2174	offers similar expressive power as POE and IO::Lambda, using conventional
		2175	Perl syntax. This means that both the echo server and the client are 100%
		2176	non-blocking, further placing it at a disadvantage.
		2177
		2178	As you can see, the AnyEvent + EV combination even beats the
		2179	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2180	backend easily beats IO::Lambda and POE.
		2181
		2182	And even the 100% non-blocking version written using the high-level (and
		2183	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2184	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2185	in a non-blocking way.
		2186
		2187	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2188	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2189	part of the IO::lambda distribution and were used without any changes.
		2190
		2191
		2192	=head1 SIGNALS
		2193
		2194	AnyEvent currently installs handlers for these signals:
		2195
		2196	=over 4
		2197
		2198	=item SIGCHLD
		2199
		2200	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2201	emulation for event loops that do not support them natively. Also, some
		2202	event loops install a similar handler.
		2203
		2204	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2205	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2206
		2207	=item SIGPIPE
		2208
		2209	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2210	when AnyEvent gets loaded.
		2211
		2212	The rationale for this is that AnyEvent users usually do not really depend
		2213	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2214	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2215	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2216	some random socket.
		2217
		2218	The rationale for installing a no-op handler as opposed to ignoring it is
		2219	that this way, the handler will be restored to defaults on exec.
		2220
		2221	Feel free to install your own handler, or reset it to defaults.
		2222
		2223	=back
		2224
		2225	=cut
		2226
		2227	undef $SIG{CHLD}
		2228	if $SIG{CHLD} eq 'IGNORE';
		2229
		2230	$SIG{PIPE} = sub { }
		2231	unless defined $SIG{PIPE};
		2232
		2233	=head1 RECOMMENDED/OPTIONAL MODULES
		2234
		2235	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2236	it's built-in modules) are required to use it.
		2237
		2238	That does not mean that AnyEvent won't take advantage of some additional
		2239	modules if they are installed.
		2240
		2241	This section epxlains which additional modules will be used, and how they
		2242	affect AnyEvent's operetion.
		2243
		2244	=over 4
		2245
		2246	=item L<Async::Interrupt>
		2247
		2248	This slightly arcane module is used to implement fast signal handling: To
		2249	my knowledge, there is no way to do completely race-free and quick
		2250	signal handling in pure perl. To ensure that signals still get
		2251	delivered, AnyEvent will start an interval timer to wake up perl (and
		2252	catch the signals) with soemd elay (default is 10 seconds, look for
		2253	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2254
		2255	If this module is available, then it will be used to implement signal
		2256	catching, which means that signals will not be delayed, and the event loop
		2257	will not be interrupted regularly, which is more efficient (And good for
		2258	battery life on laptops).
		2259
		2260	This affects not just the pure-perl event loop, but also other event loops
		2261	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2262
		2263	=item L<EV>
		2264
		2265	This module isn't really "optional", as it is simply one of the backend
		2266	event loops that AnyEvent can use. However, it is simply the best event
		2267	loop available in terms of features, speed and stability: It supports
		2268	the AnyEvent API optimally, implements all the watcher types in XS, does
		2269	automatic timer adjustments even when no monotonic clock is available,
		2270	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2271	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2272	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2273
		2274	=item L<Guard>
		2275
		2276	The guard module, when used, will be used to implement
		2277	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2278	lot less memory), but otherwise doesn't affect guard operation much. It is
		2279	purely used for performance.
		2280
		2281	=item L<JSON> and L<JSON::XS>
		2282
		2283	This module is required when you want to read or write JSON data via
		2284	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2285	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2286
		2287	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2288	installed.
		2289
		2290	=item L<Net::SSLeay>
		2291
		2292	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2293	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2294	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2295
		2296	=item L<Time::HiRes>
		2297
		2298	This module is part of perl since release 5.008. It will be used when the
		2299	chosen event library does not come with a timing source on it's own. The
		2300	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2301	try to use a monotonic clock for timing stability.
		2302
		2303	=back
		2304
1545		2305
1546	=head1 FORK	2306	=head1 FORK
1547		2307
1548	Most event libraries are not fork-safe. The ones who are usually are	2308	Most event libraries are not fork-safe. The ones who are usually are
1549	because they rely on inefficient but fork-safe C<select> or C<poll>	2309	because they rely on inefficient but fork-safe C<select> or C<poll>
1550	calls. Only L<EV> is fully fork-aware.	2310	calls. Only L<EV> is fully fork-aware.
1551		2311
1552	If you have to fork, you must either do so I<before> creating your first	2312	If you have to fork, you must either do so I<before> creating your first
1553	watcher OR you must not use AnyEvent at all in the child.	2313	watcher OR you must not use AnyEvent at all in the child OR you must do
		2314	something completely out of the scope of AnyEvent.
1554		2315
1555		2316
1556	=head1 SECURITY CONSIDERATIONS	2317	=head1 SECURITY CONSIDERATIONS
1557		2318
1558	AnyEvent can be forced to load any event model via	2319	AnyEvent can be forced to load any event model via
…		…
1563	specified in the variable.	2324	specified in the variable.
1564		2325
1565	You can make AnyEvent completely ignore this variable by deleting it	2326	You can make AnyEvent completely ignore this variable by deleting it
1566	before the first watcher gets created, e.g. with a C<BEGIN> block:	2327	before the first watcher gets created, e.g. with a C<BEGIN> block:
1567		2328
1568	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2329	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1569		2330
1570	use AnyEvent;	2331	use AnyEvent;
1571		2332
1572	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2333	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1573	be used to probe what backend is used and gain other information (which is	2334	be used to probe what backend is used and gain other information (which is
1574	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2335	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2336	$ENV{PERL_ANYEVENT_STRICT}.
		2337
		2338	Note that AnyEvent will remove I<all> environment variables starting with
		2339	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2340	enabled.
		2341
		2342
		2343	=head1 BUGS
		2344
		2345	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2346	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2347	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2348	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2349	pronounced).
1575		2350
1576		2351
1577	=head1 SEE ALSO	2352	=head1 SEE ALSO
1578		2353
1579	Utility functions: L<AnyEvent::Util>.	2354	Utility functions: L<AnyEvent::Util>.
…		…
1582	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2357	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1583		2358
1584	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2359	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1585	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2360	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1586	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2361	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1587	L<AnyEvent::Impl::POE>.	2362	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1588		2363
1589	Non-blocking file handles, sockets, TCP clients and	2364	Non-blocking file handles, sockets, TCP clients and
1590	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2365	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1591		2366
1592	Asynchronous DNS: L<AnyEvent::DNS>.	2367	Asynchronous DNS: L<AnyEvent::DNS>.
1593		2368
1594	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2369	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2370	L<Coro::Event>,
1595		2371
1596	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2372	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2373	L<AnyEvent::HTTP>.
1597		2374
1598		2375
1599	=head1 AUTHOR	2376	=head1 AUTHOR
1600		2377
1601	Marc Lehmann <schmorp@schmorp.de>	2378	Marc Lehmann <schmorp@schmorp.de>
1602	http://home.schmorp.de/	2379	http://home.schmorp.de/
1603		2380
1604	=cut	2381	=cut
1605		2382
1606	1	2383	1
1607		2384

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