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Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs.
Revision 1.249 by root, Mon Jul 20 06:00:42 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
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.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Respository>, at L<http://anyevent.schmorp.de>, for more info.
22		53
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		55
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
27		58
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
30		61
31	First and foremost, I<AnyEvent is not an event model> itself, it only	62	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	63	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,	64	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,	65	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	66	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
37		69
38	The goal of AnyEvent is to offer module authors the ability to do event	70	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	71	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	72	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	73	module users into the same thing by forcing them to use the same event
42	model you use.	74	model you use.
43		75
44	For modules like POE or IO::Async (which is a total misnomer as it is	76	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	77	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	78	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	79	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	80	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.	81	module are I<also> forced to use the same event loop you use.
50		82
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	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	85	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,	86	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	87	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	88	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	89	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).	90	to AnyEvent, too, so it is future-proof).
59		91
60	In addition to being free of having to use I<the one and only true event	92	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	93	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	94	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	95	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
124	is in control).	156	is in control).
125		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
126	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	166	to it).
129		167
130	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	171	example), or need to refer to their watcher object in other ways.
134		172
135	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
136		174
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
139	undef $w;	177	undef $w;
140	});	178	});
141		179
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	180	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
144	declared.	182	declared.
145		183
146	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
147		185
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
150		188
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
152	for events. C<poll> must be a string that is either C<r> or C<w>,	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
154	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		200
157	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
160		204
…		…
164		208
165	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	210	always use non-blocking calls when reading/writing from/to your file
167	handles.	211	handles.
168		212
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	213	Example: wait for readability of STDIN, then read a line and disable the
		214	watcher.
		215
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	218	warn "read: $input\n";
175	undef $w;	219	undef $w;
176	});	220	});
…		…
186		230
187	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
190		234
191	The timer callback will be invoked at most once: if you want a repeating	235	The callback will normally be invoked once only. If you specify another
192	timer you have to create a new watcher (this is a limitation by both Tk	236	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
194		240
195	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
196		244
197	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	248	warn "timeout\n";
200	});	249	});
201		250
202	# to cancel the timer:	251	# to cancel the timer:
203	undef $w;	252	undef $w;
204		253
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	254	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		255
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
213	};	258	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		259
218	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
219		261
220	There are two ways to handle timers: based on real time (relative, "fire	262	There are two ways to handle timers: based on real time (relative, "fire
221	in 10 seconds") and based on wallclock time (absolute, "fire at 12	263	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
233	timers.	275	timers.
234		276
235	AnyEvent always prefers relative timers, if available, matching the	277	AnyEvent always prefers relative timers, if available, matching the
236	AnyEvent API.	278	AnyEvent API.
237		279
		280	AnyEvent has two additional methods that return the "current time":
		281
		282	=over 4
		283
		284	=item AnyEvent->time
		285
		286	This returns the "current wallclock time" as a fractional number of
		287	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		288	return, and the result is guaranteed to be compatible with those).
		289
		290	It progresses independently of any event loop processing, i.e. each call
		291	will check the system clock, which usually gets updated frequently.
		292
		293	=item AnyEvent->now
		294
		295	This also returns the "current wallclock time", but unlike C<time>, above,
		296	this value might change only once per event loop iteration, depending on
		297	the event loop (most return the same time as C<time>, above). This is the
		298	time that AnyEvent's timers get scheduled against.
		299
		300	I<In almost all cases (in all cases if you don't care), this is the
		301	function to call when you want to know the current time.>
		302
		303	This function is also often faster then C<< AnyEvent->time >>, and
		304	thus the preferred method if you want some timestamp (for example,
		305	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		306
		307	The rest of this section is only of relevance if you try to be very exact
		308	with your timing, you can skip it without bad conscience.
		309
		310	For a practical example of when these times differ, consider L<Event::Lib>
		311	and L<EV> and the following set-up:
		312
		313	The event loop is running and has just invoked one of your callback at
		314	time=500 (assume no other callbacks delay processing). In your callback,
		315	you wait a second by executing C<sleep 1> (blocking the process for a
		316	second) and then (at time=501) you create a relative timer that fires
		317	after three seconds.
		318
		319	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		320	both return C<501>, because that is the current time, and the timer will
		321	be scheduled to fire at time=504 (C<501> + C<3>).
		322
		323	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		324	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		325	last event processing phase started. With L<EV>, your timer gets scheduled
		326	to run at time=503 (C<500> + C<3>).
		327
		328	In one sense, L<Event::Lib> is more exact, as it uses the current time
		329	regardless of any delays introduced by event processing. However, most
		330	callbacks do not expect large delays in processing, so this causes a
		331	higher drift (and a lot more system calls to get the current time).
		332
		333	In another sense, L<EV> is more exact, as your timer will be scheduled at
		334	the same time, regardless of how long event processing actually took.
		335
		336	In either case, if you care (and in most cases, you don't), then you
		337	can get whatever behaviour you want with any event loop, by taking the
		338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		339	account.
		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
		356	=back
		357
238	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
239		359
240	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
241	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
242	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
243		363
244	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
245	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
246	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
247		367
…		…
249	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
250	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
251	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
252		372
253	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
254	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
255		376
256	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
257	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
258		380
259	Example: exit on SIGINT	381	Example: exit on SIGINT
260		382
261	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
262		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
263	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
264		402
265	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
266		404
267	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (if set to C<0>, it
268	watches for any child process exit). The watcher will trigger as often	406	watches for any child process exit). The watcher will triggered only when
269	as status change for the child are received. This works by installing a	407	the child process has finished and an exit status is available, not on
270	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
271	and exit status (as returned by waitpid), so unlike other watcher types,	409
272	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
273		418
274	There is a slight catch to child watchers, however: you usually start them	419	There is a slight catch to child watchers, however: you usually start them
275	I<after> the child process was created, and this means the process could	420	I<after> the child process was created, and this means the process could
276	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
277		422
278	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	see their AnyEvent::Impl manpages for details), but even for event models
279	event models that I<do> handle this correctly, they usually need to be	425	that I<do> handle this correctly, they usually need to be loaded before
280	loaded before the process exits (i.e. before you fork in the first place).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
281		429
282	This means you cannot create a child watcher as the very first thing in an	430	This means you cannot create a child watcher as the very first
283	AnyEvent program, you I<have> to create at least one watcher before you	431	thing in an AnyEvent program, you I<have> to create at least one
284	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
285		438
286	Example: fork a process and wait for it	439	Example: fork a process and wait for it
287		440
288	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
289		442
290	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
291		444
292	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
293	pid => $pid,	446	pid => $pid,
294	cb => sub {	447	cb => sub {
295	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
296	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
297	$done->send;	450	$done->send;
298	},	451	},
299	);	452	);
300		453
301	# do something else, then wait for process exit	454	# do something else, then wait for process exit
302	$done->recv;	455	$done->recv;
		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
303		491
304	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
305		493
306	If you are familiar with some event loops you will know that all of them	494	If you are familiar with some event loops you will know that all of them
307	require you to run some blocking "loop", "run" or similar function that	495	require you to run some blocking "loop", "run" or similar function that
308	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
309		497
310	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
311	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
312		500
313	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
314	because they represent a condition that must become true.	502	because they represent a condition that must become true.
		503
		504	Now is probably a good time to look at the examples further below.
315		505
316	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
317	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
318	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
319	becomes true.	509	becomes true, with the condition variable as the first argument (but not
		510	the results).
320		511
321	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
322	by calling the C<send> method (or calling the condition variable as if it	513	by calling the C<send> method (or calling the condition variable as if it
323	were a callback, read about the caveats in the description for the C<<	514	were a callback, read about the caveats in the description for the C<<
324	->send >> method).	515	->send >> method).
…		…
370	after => 1,	561	after => 1,
371	cb => sub { $result_ready->send },	562	cb => sub { $result_ready->send },
372	);	563	);
373		564
374	# this "blocks" (while handling events) till the callback	565	# this "blocks" (while handling events) till the callback
375	# calls send	566	# calls -<send
376	$result_ready->recv;	567	$result_ready->recv;
377		568
378	Example: wait for a timer, but take advantage of the fact that	569	Example: wait for a timer, but take advantage of the fact that condition
379	condition variables are also code references.	570	variables are also callable directly.
380		571
381	my $done = AnyEvent->condvar;	572	my $done = AnyEvent->condvar;
382	my $delay = AnyEvent->timer (after => 5, cb => $done);	573	my $delay = AnyEvent->timer (after => 5, cb => $done);
383	$done->recv;	574	$done->recv;
		575
		576	Example: Imagine an API that returns a condvar and doesn't support
		577	callbacks. This is how you make a synchronous call, for example from
		578	the main program:
		579
		580	use AnyEvent::CouchDB;
		581
		582	...
		583
		584	my @info = $couchdb->info->recv;
		585
		586	And this is how you would just set a callback to be called whenever the
		587	results are available:
		588
		589	$couchdb->info->cb (sub {
		590	my @info = $_[0]->recv;
		591	});
384		592
385	=head3 METHODS FOR PRODUCERS	593	=head3 METHODS FOR PRODUCERS
386		594
387	These methods should only be used by the producing side, i.e. the	595	These methods should only be used by the producing side, i.e. the
388	code/module that eventually sends the signal. Note that it is also	596	code/module that eventually sends the signal. Note that it is also
…		…
401	immediately from within send.	609	immediately from within send.
402		610
403	Any arguments passed to the C<send> call will be returned by all	611	Any arguments passed to the C<send> call will be returned by all
404	future C<< ->recv >> calls.	612	future C<< ->recv >> calls.
405		613
406	Condition variables are overloaded so one can call them directly	614	Condition variables are overloaded so one can call them directly (as if
407	(as a code reference). Calling them directly is the same as calling	615	they were a code reference). Calling them directly is the same as calling
408	C<send>. Note, however, that many C-based event loops do not handle	616	C<send>.
409	overloading, so as tempting as it may be, passing a condition variable
410	instead of a callback does not work. Both the pure perl and EV loops
411	support overloading, however, as well as all functions that use perl to
412	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
413	example).
414		617
415	=item $cv->croak ($error)	618	=item $cv->croak ($error)
416		619
417	Similar to send, but causes all call's to C<< ->recv >> to invoke	620	Similar to send, but causes all call's to C<< ->recv >> to invoke
418	C<Carp::croak> with the given error message/object/scalar.	621	C<Carp::croak> with the given error message/object/scalar.
419		622
420	This can be used to signal any errors to the condition variable	623	This can be used to signal any errors to the condition variable
421	user/consumer.	624	user/consumer. Doing it this way instead of calling C<croak> directly
		625	delays the error detetcion, but has the overwhelmign advantage that it
		626	diagnoses the error at the place where the result is expected, and not
		627	deep in some event clalback without connection to the actual code causing
		628	the problem.
422		629
423	=item $cv->begin ([group callback])	630	=item $cv->begin ([group callback])
424		631
425	=item $cv->end	632	=item $cv->end
426
427	These two methods are EXPERIMENTAL and MIGHT CHANGE.
428		633
429	These two methods can be used to combine many transactions/events into	634	These two methods can be used to combine many transactions/events into
430	one. For example, a function that pings many hosts in parallel might want	635	one. For example, a function that pings many hosts in parallel might want
431	to use a condition variable for the whole process.	636	to use a condition variable for the whole process.
432		637
…		…
434	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	639	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
435	>>, the (last) callback passed to C<begin> will be executed. That callback	640	>>, the (last) callback passed to C<begin> will be executed. That callback
436	is I<supposed> to call C<< ->send >>, but that is not required. If no	641	is I<supposed> to call C<< ->send >>, but that is not required. If no
437	callback was set, C<send> will be called without any arguments.	642	callback was set, C<send> will be called without any arguments.
438		643
439	Let's clarify this with the ping example:	644	You can think of C<< $cv->send >> giving you an OR condition (one call
		645	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		646	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		647
		648	Let's start with a simple example: you have two I/O watchers (for example,
		649	STDOUT and STDERR for a program), and you want to wait for both streams to
		650	close before activating a condvar:
		651
		652	my $cv = AnyEvent->condvar;
		653
		654	$cv->begin; # first watcher
		655	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		656	defined sysread $fh1, my $buf, 4096
		657	or $cv->end;
		658	});
		659
		660	$cv->begin; # second watcher
		661	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		662	defined sysread $fh2, my $buf, 4096
		663	or $cv->end;
		664	});
		665
		666	$cv->recv;
		667
		668	This works because for every event source (EOF on file handle), there is
		669	one call to C<begin>, so the condvar waits for all calls to C<end> before
		670	sending.
		671
		672	The ping example mentioned above is slightly more complicated, as the
		673	there are results to be passwd back, and the number of tasks that are
		674	begung can potentially be zero:
440		675
441	my $cv = AnyEvent->condvar;	676	my $cv = AnyEvent->condvar;
442		677
443	my %result;	678	my %result;
444	$cv->begin (sub { $cv->send (\%result) });	679	$cv->begin (sub { $cv->send (\%result) });
…		…
464	loop, which serves two important purposes: first, it sets the callback	699	loop, which serves two important purposes: first, it sets the callback
465	to be called once the counter reaches C<0>, and second, it ensures that	700	to be called once the counter reaches C<0>, and second, it ensures that
466	C<send> is called even when C<no> hosts are being pinged (the loop	701	C<send> is called even when C<no> hosts are being pinged (the loop
467	doesn't execute once).	702	doesn't execute once).
468		703
469	This is the general pattern when you "fan out" into multiple subrequests:	704	This is the general pattern when you "fan out" into multiple (but
470	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	705	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
471	is called at least once, and then, for each subrequest you start, call	706	the callback and ensure C<end> is called at least once, and then, for each
472	C<begin> and for each subrequest you finish, call C<end>.	707	subrequest you start, call C<begin> and for each subrequest you finish,
		708	call C<end>.
473		709
474	=back	710	=back
475		711
476	=head3 METHODS FOR CONSUMERS	712	=head3 METHODS FOR CONSUMERS
477		713
…		…
493	function will call C<croak>.	729	function will call C<croak>.
494		730
495	In list context, all parameters passed to C<send> will be returned,	731	In list context, all parameters passed to C<send> will be returned,
496	in scalar context only the first one will be returned.	732	in scalar context only the first one will be returned.
497		733
		734	Note that doing a blocking wait in a callback is not supported by any
		735	event loop, that is, recursive invocation of a blocking C<< ->recv
		736	>> is not allowed, and the C<recv> call will C<croak> if such a
		737	condition is detected. This condition can be slightly loosened by using
		738	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		739	any thread that doesn't run the event loop itself.
		740
498	Not all event models support a blocking wait - some die in that case	741	Not all event models support a blocking wait - some die in that case
499	(programs might want to do that to stay interactive), so I<if you are	742	(programs might want to do that to stay interactive), so I<if you are
500	using this from a module, never require a blocking wait>, but let the	743	using this from a module, never require a blocking wait>. Instead, let the
501	caller decide whether the call will block or not (for example, by coupling	744	caller decide whether the call will block or not (for example, by coupling
502	condition variables with some kind of request results and supporting	745	condition variables with some kind of request results and supporting
503	callbacks so the caller knows that getting the result will not block,	746	callbacks so the caller knows that getting the result will not block,
504	while still supporting blocking waits if the caller so desires).	747	while still supporting blocking waits if the caller so desires).
505		748
506	Another reason I<never> to C<< ->recv >> in a module is that you cannot
507	sensibly have two C<< ->recv >>'s in parallel, as that would require
508	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
509	can supply.
510
511	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
512	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
513	versions and also integrates coroutines into AnyEvent, making blocking
514	C<< ->recv >> calls perfectly safe as long as they are done from another
515	coroutine (one that doesn't run the event loop).
516
517	You can ensure that C<< -recv >> never blocks by setting a callback and	749	You can ensure that C<< -recv >> never blocks by setting a callback and
518	only calling C<< ->recv >> from within that callback (or at a later	750	only calling C<< ->recv >> from within that callback (or at a later
519	time). This will work even when the event loop does not support blocking	751	time). This will work even when the event loop does not support blocking
520	waits otherwise.	752	waits otherwise.
521		753
522	=item $bool = $cv->ready	754	=item $bool = $cv->ready
523		755
524	Returns true when the condition is "true", i.e. whether C<send> or	756	Returns true when the condition is "true", i.e. whether C<send> or
525	C<croak> have been called.	757	C<croak> have been called.
526		758
527	=item $cb = $cv->cb ([new callback])	759	=item $cb = $cv->cb ($cb->($cv))
528		760
529	This is a mutator function that returns the callback set and optionally	761	This is a mutator function that returns the callback set and optionally
530	replaces it before doing so.	762	replaces it before doing so.
531		763
532	The callback will be called when the condition becomes "true", i.e. when	764	The callback will be called when the condition becomes "true", i.e. when
533	C<send> or C<croak> are called. Calling C<recv> inside the callback	765	C<send> or C<croak> are called, with the only argument being the condition
534	or at any later time is guaranteed not to block.	766	variable itself. Calling C<recv> inside the callback or at any later time
		767	is guaranteed not to block.
535		768
536	=back	769	=back
537		770
		771	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		772
		773	The available backend classes are (every class has its own manpage):
		774
		775	=over 4
		776
		777	=item Backends that are autoprobed when no other event loop can be found.
		778
		779	EV is the preferred backend when no other event loop seems to be in
		780	use. If EV is not installed, then AnyEvent will try Event, and, failing
		781	that, will fall back to its own pure-perl implementation, which is
		782	available everywhere as it comes with AnyEvent itself.
		783
		784	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		785	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		786	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		787
		788	=item Backends that are transparently being picked up when they are used.
		789
		790	These will be used when they are currently loaded when the first watcher
		791	is created, in which case it is assumed that the application is using
		792	them. This means that AnyEvent will automatically pick the right backend
		793	when the main program loads an event module before anything starts to
		794	create watchers. Nothing special needs to be done by the main program.
		795
		796	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		797	AnyEvent::Impl::Tk based on Tk, very broken.
		798	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		799	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		800
		801	=item Backends with special needs.
		802
		803	Qt requires the Qt::Application to be instantiated first, but will
		804	otherwise be picked up automatically. As long as the main program
		805	instantiates the application before any AnyEvent watchers are created,
		806	everything should just work.
		807
		808	AnyEvent::Impl::Qt based on Qt.
		809
		810	Support for IO::Async can only be partial, as it is too broken and
		811	architecturally limited to even support the AnyEvent API. It also
		812	is the only event loop that needs the loop to be set explicitly, so
		813	it can only be used by a main program knowing about AnyEvent. See
		814	L<AnyEvent::Impl::Async> for the gory details.
		815
		816	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		817
		818	=item Event loops that are indirectly supported via other backends.
		819
		820	Some event loops can be supported via other modules:
		821
		822	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		823
		824	B<WxWidgets> has no support for watching file handles. However, you can
		825	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		826	polls 20 times per second, which was considered to be too horrible to even
		827	consider for AnyEvent.
		828
		829	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		830	backend, so it can be supported through POE.
		831
		832	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		833	load L<POE> when detecting them, in the hope that POE will pick them up,
		834	in which case everything will be automatic.
		835
		836	=back
		837
538	=head1 GLOBAL VARIABLES AND FUNCTIONS	838	=head1 GLOBAL VARIABLES AND FUNCTIONS
539		839
		840	These are not normally required to use AnyEvent, but can be useful to
		841	write AnyEvent extension modules.
		842
540	=over 4	843	=over 4
541		844
542	=item $AnyEvent::MODEL	845	=item $AnyEvent::MODEL
543		846
544	Contains C<undef> until the first watcher is being created. Then it	847	Contains C<undef> until the first watcher is being created, before the
		848	backend has been autodetected.
		849
545	contains the event model that is being used, which is the name of the	850	Afterwards it contains the event model that is being used, which is the
546	Perl class implementing the model. This class is usually one of the	851	name of the Perl class implementing the model. This class is usually one
547	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	852	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
548	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	853	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
549		854	will be C<urxvt::anyevent>).
550	The known classes so far are:
551
552	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
553	AnyEvent::Impl::Event based on Event, second best choice.
554	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
555	AnyEvent::Impl::Glib based on Glib, third-best choice.
556	AnyEvent::Impl::Tk based on Tk, very bad choice.
557	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
558	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
559	AnyEvent::Impl::POE based on POE, not generic enough for full support.
560
561	There is no support for WxWidgets, as WxWidgets has no support for
562	watching file handles. However, you can use WxWidgets through the
563	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
564	second, which was considered to be too horrible to even consider for
565	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
566	it's adaptor.
567
568	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
569	autodetecting them.
570		855
571	=item AnyEvent::detect	856	=item AnyEvent::detect
572		857
573	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	858	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
574	if necessary. You should only call this function right before you would	859	if necessary. You should only call this function right before you would
575	have created an AnyEvent watcher anyway, that is, as late as possible at	860	have created an AnyEvent watcher anyway, that is, as late as possible at
576	runtime.	861	runtime, and not e.g. while initialising of your module.
		862
		863	If you need to do some initialisation before AnyEvent watchers are
		864	created, use C<post_detect>.
577		865
578	=item $guard = AnyEvent::post_detect { BLOCK }	866	=item $guard = AnyEvent::post_detect { BLOCK }
579		867
580	Arranges for the code block to be executed as soon as the event model is	868	Arranges for the code block to be executed as soon as the event model is
581	autodetected (or immediately if this has already happened).	869	autodetected (or immediately if this has already happened).
		870
		871	The block will be executed I<after> the actual backend has been detected
		872	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		873	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		874	other initialisations - see the sources of L<AnyEvent::Strict> or
		875	L<AnyEvent::AIO> to see how this is used.
		876
		877	The most common usage is to create some global watchers, without forcing
		878	event module detection too early, for example, L<AnyEvent::AIO> creates
		879	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		880	avoid autodetecting the event module at load time.
582		881
583	If called in scalar or list context, then it creates and returns an object	882	If called in scalar or list context, then it creates and returns an object
584	that automatically removes the callback again when it is destroyed. See	883	that automatically removes the callback again when it is destroyed. See
585	L<Coro::BDB> for a case where this is useful.	884	L<Coro::BDB> for a case where this is useful.
586		885
…		…
589	If there are any code references in this array (you can C<push> to it	888	If there are any code references in this array (you can C<push> to it
590	before or after loading AnyEvent), then they will called directly after	889	before or after loading AnyEvent), then they will called directly after
591	the event loop has been chosen.	890	the event loop has been chosen.
592		891
593	You should check C<$AnyEvent::MODEL> before adding to this array, though:	892	You should check C<$AnyEvent::MODEL> before adding to this array, though:
594	if it contains a true value then the event loop has already been detected,	893	if it is defined then the event loop has already been detected, and the
595	and the array will be ignored.	894	array will be ignored.
596		895
597	Best use C<AnyEvent::post_detect { BLOCK }> instead.	896	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		897	it,as it takes care of these details.
		898
		899	This variable is mainly useful for modules that can do something useful
		900	when AnyEvent is used and thus want to know when it is initialised, but do
		901	not need to even load it by default. This array provides the means to hook
		902	into AnyEvent passively, without loading it.
598		903
599	=back	904	=back
600		905
601	=head1 WHAT TO DO IN A MODULE	906	=head1 WHAT TO DO IN A MODULE
602		907
…		…
657		962
658		963
659	=head1 OTHER MODULES	964	=head1 OTHER MODULES
660		965
661	The following is a non-exhaustive list of additional modules that use	966	The following is a non-exhaustive list of additional modules that use
662	AnyEvent and can therefore be mixed easily with other AnyEvent modules	967	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
663	in the same program. Some of the modules come with AnyEvent, some are	968	modules and other event loops in the same program. Some of the modules
664	available via CPAN.	969	come with AnyEvent, most are available via CPAN.
665		970
666	=over 4	971	=over 4
667		972
668	=item L<AnyEvent::Util>	973	=item L<AnyEvent::Util>
669		974
670	Contains various utility functions that replace often-used but blocking	975	Contains various utility functions that replace often-used but blocking
671	functions such as C<inet_aton> by event-/callback-based versions.	976	functions such as C<inet_aton> by event-/callback-based versions.
672
673	=item L<AnyEvent::Handle>
674
675	Provide read and write buffers and manages watchers for reads and writes.
676		977
677	=item L<AnyEvent::Socket>	978	=item L<AnyEvent::Socket>
678		979
679	Provides various utility functions for (internet protocol) sockets,	980	Provides various utility functions for (internet protocol) sockets,
680	addresses and name resolution. Also functions to create non-blocking tcp	981	addresses and name resolution. Also functions to create non-blocking tcp
681	connections or tcp servers, with IPv6 and SRV record support and more.	982	connections or tcp servers, with IPv6 and SRV record support and more.
682		983
		984	=item L<AnyEvent::Handle>
		985
		986	Provide read and write buffers, manages watchers for reads and writes,
		987	supports raw and formatted I/O, I/O queued and fully transparent and
		988	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		989
683	=item L<AnyEvent::DNS>	990	=item L<AnyEvent::DNS>
684		991
685	Provides rich asynchronous DNS resolver capabilities.	992	Provides rich asynchronous DNS resolver capabilities.
686		993
		994	=item L<AnyEvent::HTTP>
		995
		996	A simple-to-use HTTP library that is capable of making a lot of concurrent
		997	HTTP requests.
		998
687	=item L<AnyEvent::HTTPD>	999	=item L<AnyEvent::HTTPD>
688		1000
689	Provides a simple web application server framework.	1001	Provides a simple web application server framework.
690		1002
691	=item L<AnyEvent::FastPing>	1003	=item L<AnyEvent::FastPing>
692		1004
693	The fastest ping in the west.	1005	The fastest ping in the west.
694		1006
		1007	=item L<AnyEvent::DBI>
		1008
		1009	Executes L<DBI> requests asynchronously in a proxy process.
		1010
		1011	=item L<AnyEvent::AIO>
		1012
		1013	Truly asynchronous I/O, should be in the toolbox of every event
		1014	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1015	together.
		1016
		1017	=item L<AnyEvent::BDB>
		1018
		1019	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1020	L<BDB> and AnyEvent together.
		1021
		1022	=item L<AnyEvent::GPSD>
		1023
		1024	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1025
695	=item L<Net::IRC3>	1026	=item L<AnyEvent::IRC>
696		1027
697	AnyEvent based IRC client module family.	1028	AnyEvent based IRC client module family (replacing the older Net::IRC3).
698		1029
699	=item L<Net::XMPP2>	1030	=item L<AnyEvent::XMPP>
700		1031
701	AnyEvent based XMPP (Jabber protocol) module family.	1032	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1033	Net::XMPP2>.
		1034
		1035	=item L<AnyEvent::IGS>
		1036
		1037	A non-blocking interface to the Internet Go Server protocol (used by
		1038	L<App::IGS>).
702		1039
703	=item L<Net::FCP>	1040	=item L<Net::FCP>
704		1041
705	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1042	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
706	of AnyEvent.	1043	of AnyEvent.
…		…
711		1048
712	=item L<Coro>	1049	=item L<Coro>
713		1050
714	Has special support for AnyEvent via L<Coro::AnyEvent>.	1051	Has special support for AnyEvent via L<Coro::AnyEvent>.
715		1052
716	=item L<AnyEvent::AIO>, L<IO::AIO>
717
718	Truly asynchronous I/O, should be in the toolbox of every event
719	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
720	together.
721
722	=item L<AnyEvent::BDB>, L<BDB>
723
724	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
725	IO::AIO and AnyEvent together.
726
727	=item L<IO::Lambda>
728
729	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
730
731	=back	1053	=back
732		1054
733	=cut	1055	=cut
734		1056
735	package AnyEvent;	1057	package AnyEvent;
736		1058
		1059	# basically a tuned-down version of common::sense
		1060	sub common_sense {
737	no warnings;	1061	# no warnings
738	use strict;	1062	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1063	# use strict vars subs
		1064	$^H |= 0x00000600;
		1065	}
739		1066
		1067	BEGIN { AnyEvent::common_sense }
		1068
740	use Carp;	1069	use Carp ();
741		1070
742	our $VERSION = '4.05';	1071	our $VERSION = 4.85;
743	our $MODEL;	1072	our $MODEL;
744		1073
745	our $AUTOLOAD;	1074	our $AUTOLOAD;
746	our @ISA;	1075	our @ISA;
747		1076
748	our @REGISTRY;	1077	our @REGISTRY;
749		1078
750	our $WIN32;	1079	our $WIN32;
751		1080
		1081	our $VERBOSE;
		1082
752	BEGIN {	1083	BEGIN {
753	my $win32 = ! ! ($^O =~ /mswin32/i);	1084	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
754	eval "sub WIN32(){ $win32 }";	1085	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
755	}
756		1086
		1087	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1088	if ${^TAINT};
		1089
757	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1090	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1091
		1092	}
		1093
		1094	our $MAX_SIGNAL_LATENCY = 10;
758		1095
759	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1096	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
760		1097
761	{	1098	{
762	my $idx;	1099	my $idx;
…		…
770	[Event:: => AnyEvent::Impl::Event::],	1107	[Event:: => AnyEvent::Impl::Event::],
771	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1108	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
772	# everything below here will not be autoprobed	1109	# everything below here will not be autoprobed
773	# as the pureperl backend should work everywhere	1110	# as the pureperl backend should work everywhere
774	# and is usually faster	1111	# and is usually faster
775	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
776	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1112	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
777	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1113	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1114	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
778	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1115	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1116	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
780	[Wx:: => AnyEvent::Impl::POE::],	1117	[Wx:: => AnyEvent::Impl::POE::],
781	[Prima:: => AnyEvent::Impl::POE::],	1118	[Prima:: => AnyEvent::Impl::POE::],
		1119	# IO::Async is just too broken - we would need workarounds for its
		1120	# byzantine signal and broken child handling, among others.
		1121	# IO::Async is rather hard to detect, as it doesn't have any
		1122	# obvious default class.
		1123	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1124	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
782	);	1126	);
783		1127
784	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1128	our %method = map +($_ => 1),
		1129	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
785		1130
786	our @post_detect;	1131	our @post_detect;
787		1132
788	sub post_detect(&) {	1133	sub post_detect(&) {
789	my ($cb) = @_;	1134	my ($cb) = @_;
…		…
794	1	1139	1
795	} else {	1140	} else {
796	push @post_detect, $cb;	1141	push @post_detect, $cb;
797		1142
798	defined wantarray	1143	defined wantarray
799	? bless \$cb, "AnyEvent::Util::PostDetect"	1144	? bless \$cb, "AnyEvent::Util::postdetect"
800	: ()	1145	: ()
801	}	1146	}
802	}	1147	}
803		1148
804	sub AnyEvent::Util::PostDetect::DESTROY {	1149	sub AnyEvent::Util::postdetect::DESTROY {
805	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1150	@post_detect = grep $_ != ${$_[0]}, @post_detect;
806	}	1151	}
807		1152
808	sub detect() {	1153	sub detect() {
809	unless ($MODEL) {	1154	unless ($MODEL) {
810	no strict 'refs';
811	local $SIG{__DIE__};	1155	local $SIG{__DIE__};
812		1156
813	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1157	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
814	my $model = "AnyEvent::Impl::$1";	1158	my $model = "AnyEvent::Impl::$1";
815	if (eval "require $model") {	1159	if (eval "require $model") {
816	$MODEL = $model;	1160	$MODEL = $model;
817	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1161	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
818	} else {	1162	} else {
819	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1163	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
820	}	1164	}
821	}	1165	}
822		1166
823	# check for already loaded models	1167	# check for already loaded models
824	unless ($MODEL) {	1168	unless ($MODEL) {
825	for (@REGISTRY, @models) {	1169	for (@REGISTRY, @models) {
826	my ($package, $model) = @$_;	1170	my ($package, $model) = @$_;
827	if (${"$package\::VERSION"} > 0) {	1171	if (${"$package\::VERSION"} > 0) {
828	if (eval "require $model") {	1172	if (eval "require $model") {
829	$MODEL = $model;	1173	$MODEL = $model;
830	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1174	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
831	last;	1175	last;
832	}	1176	}
833	}	1177	}
834	}	1178	}
835		1179
…		…
840	my ($package, $model) = @$_;	1184	my ($package, $model) = @$_;
841	if (eval "require $package"	1185	if (eval "require $package"
842	and ${"$package\::VERSION"} > 0	1186	and ${"$package\::VERSION"} > 0
843	and eval "require $model") {	1187	and eval "require $model") {
844	$MODEL = $model;	1188	$MODEL = $model;
845	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1189	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
846	last;	1190	last;
847	}	1191	}
848	}	1192	}
849		1193
850	$MODEL	1194	$MODEL
851	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1195	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
852	}	1196	}
853	}	1197	}
854		1198
		1199	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1200
855	unshift @ISA, $MODEL;	1201	unshift @ISA, $MODEL;
856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1202
		1203	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
857		1204
858	(shift @post_detect)->() while @post_detect;	1205	(shift @post_detect)->() while @post_detect;
859	}	1206	}
860		1207
861	$MODEL	1208	$MODEL
…		…
863		1210
864	sub AUTOLOAD {	1211	sub AUTOLOAD {
865	(my $func = $AUTOLOAD) =~ s/.*://;	1212	(my $func = $AUTOLOAD) =~ s/.*://;
866		1213
867	$method{$func}	1214	$method{$func}
868	or croak "$func: not a valid method for AnyEvent objects";	1215	or Carp::croak "$func: not a valid method for AnyEvent objects";
869		1216
870	detect unless $MODEL;	1217	detect unless $MODEL;
871		1218
872	my $class = shift;	1219	my $class = shift;
873	$class->$func (@_);	1220	$class->$func (@_);
874	}	1221	}
875		1222
		1223	# utility function to dup a filehandle. this is used by many backends
		1224	# to support binding more than one watcher per filehandle (they usually
		1225	# allow only one watcher per fd, so we dup it to get a different one).
		1226	sub _dupfh($$;$$) {
		1227	my ($poll, $fh, $r, $w) = @_;
		1228
		1229	# cygwin requires the fh mode to be matching, unix doesn't
		1230	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1231
		1232	open my $fh2, $mode, $fh
		1233	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1234
		1235	# we assume CLOEXEC is already set by perl in all important cases
		1236
		1237	($fh2, $rw)
		1238	}
		1239
876	package AnyEvent::Base;	1240	package AnyEvent::Base;
877		1241
		1242	# default implementations for many methods
		1243
		1244	sub _time {
		1245	# probe for availability of Time::HiRes
		1246	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1247	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1248	*_time = \&Time::HiRes::time;
		1249	# if (eval "use POSIX (); (POSIX::times())...
		1250	} else {
		1251	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1252	*_time = sub { time }; # epic fail
		1253	}
		1254
		1255	&_time
		1256	}
		1257
		1258	sub time { _time }
		1259	sub now { _time }
		1260	sub now_update { }
		1261
878	# default implementation for ->condvar	1262	# default implementation for ->condvar
879		1263
880	sub condvar {	1264	sub condvar {
881	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1265	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
882	}	1266	}
883		1267
884	# default implementation for ->signal	1268	# default implementation for ->signal
885		1269
886	our %SIG_CB;	1270	our $HAVE_ASYNC_INTERRUPT;
		1271	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1272	our (%SIG_ASY, %SIG_ASY_W);
		1273	our ($SIG_COUNT, $SIG_TW);
887		1274
		1275	sub _signal_exec {
		1276	$HAVE_ASYNC_INTERRUPT
		1277	? $SIGPIPE_R->drain
		1278	: sysread $SIGPIPE_R, my $dummy, 9;
		1279
		1280	while (%SIG_EV) {
		1281	for (keys %SIG_EV) {
		1282	delete $SIG_EV{$_};
		1283	$_->() for values %{ $SIG_CB{$_} || {} };
		1284	}
		1285	}
		1286	}
		1287
		1288	# install a dumym wakeupw atcher to reduce signal catching latency
		1289	sub _sig_add() {
		1290	unless ($SIG_COUNT++) {
		1291	# try to align timer on a full-second boundary, if possible
		1292	my $NOW = AnyEvent->now;
		1293
		1294	$SIG_TW = AnyEvent->timer (
		1295	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1296	interval => $MAX_SIGNAL_LATENCY,
		1297	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1298	);
		1299	}
		1300	}
		1301
		1302	sub _sig_del {
		1303	undef $SIG_TW
		1304	unless --$SIG_COUNT;
		1305	}
		1306
888	sub signal {	1307	sub _signal {
889	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
890		1309
891	my $signal = uc $arg{signal}	1310	my $signal = uc $arg{signal}
892	or Carp::croak "required option 'signal' is missing";	1311	or Carp::croak "required option 'signal' is missing";
893		1312
894	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1313	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1314
		1315	if ($HAVE_ASYNC_INTERRUPT) {
		1316	# async::interrupt
		1317
		1318	$SIG_ASY{$signal} ||= do {
		1319	my $asy = new Async::Interrupt
		1320	cb => sub { undef $SIG_EV{$signal} },
		1321	signal => $signal,
		1322	pipe => [$SIGPIPE_R->filenos],
		1323	;
		1324	$asy->pipe_autodrain (0);
		1325
		1326	$asy
		1327	};
		1328
		1329	} else {
		1330	# pure perl
		1331
895	$SIG{$signal} ||= sub {	1332	$SIG{$signal} ||= sub {
896	$_->() for values %{ $SIG_CB{$signal} || {} };	1333	local $!;
		1334	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1335	undef $SIG_EV{$signal};
		1336	};
		1337
		1338	# can't do signal processing without introducing races in pure perl,
		1339	# so limit the signal latency.
		1340	_sig_add;
897	};	1341	}
898		1342
899	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1343	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
900	}	1344	}
901		1345
		1346	sub signal {
		1347	# probe for availability of Async::Interrupt
		1348	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1349	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1350
		1351	$HAVE_ASYNC_INTERRUPT = 1;
		1352	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1353	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1354
		1355	} else {
		1356	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1357
		1358	require Fcntl;
		1359
		1360	if (AnyEvent::WIN32) {
		1361	require AnyEvent::Util;
		1362
		1363	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1364	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1366	} else {
		1367	pipe $SIGPIPE_R, $SIGPIPE_W;
		1368	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1369	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1370
		1371	# not strictly required, as $^F is normally 2, but let's make sure...
		1372	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1373	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1374	}
		1375
		1376	$SIGPIPE_R
		1377	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1378
		1379	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1380	}
		1381
		1382	*signal = \&_signal;
		1383	&signal
		1384	}
		1385
902	sub AnyEvent::Base::Signal::DESTROY {	1386	sub AnyEvent::Base::signal::DESTROY {
903	my ($signal, $cb) = @{$_[0]};	1387	my ($signal, $cb) = @{$_[0]};
904		1388
		1389	_sig_del;
		1390
905	delete $SIG_CB{$signal}{$cb};	1391	delete $SIG_CB{$signal}{$cb};
906		1392
907	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1393	$HAVE_ASYNC_INTERRUPT
		1394	? delete $SIG_ASY{$signal}
		1395	: # delete doesn't work with older perls - they then
		1396	# print weird messages, or just unconditionally exit
		1397	# instead of getting the default action.
		1398	undef $SIG{$signal}
		1399	unless keys %{ $SIG_CB{$signal} };
908	}	1400	}
909		1401
910	# default implementation for ->child	1402	# default implementation for ->child
911		1403
912	our %PID_CB;	1404	our %PID_CB;
913	our $CHLD_W;	1405	our $CHLD_W;
914	our $CHLD_DELAY_W;	1406	our $CHLD_DELAY_W;
915	our $PID_IDLE;
916	our $WNOHANG;	1407	our $WNOHANG;
917		1408
918	sub _child_wait {	1409	sub _sigchld {
919	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1410	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1411	$_->($pid, $?)
920	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1412	for values %{ $PID_CB{$pid} || {} },
921	(values %{ $PID_CB{0} || {} });	1413	values %{ $PID_CB{0} || {} };
922	}	1414	}
923
924	undef $PID_IDLE;
925	}
926
927	sub _sigchld {
928	# make sure we deliver these changes "synchronous" with the event loop.
929	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
930	undef $CHLD_DELAY_W;
931	&_child_wait;
932	});
933	}	1415	}
934		1416
935	sub child {	1417	sub child {
936	my (undef, %arg) = @_;	1418	my (undef, %arg) = @_;
937		1419
938	defined (my $pid = $arg{pid} + 0)	1420	defined (my $pid = $arg{pid} + 0)
939	or Carp::croak "required option 'pid' is missing";	1421	or Carp::croak "required option 'pid' is missing";
940		1422
941	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1423	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
942		1424
943	unless ($WNOHANG) {	1425	# WNOHANG is almost cetrainly 1 everywhere
		1426	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1427	? 1
944	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1428	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
945	}
946		1429
947	unless ($CHLD_W) {	1430	unless ($CHLD_W) {
948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1431	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
949	# child could be a zombie already, so make at least one round	1432	# child could be a zombie already, so make at least one round
950	&_sigchld;	1433	&_sigchld;
951	}	1434	}
952		1435
953	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1436	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
954	}	1437	}
955		1438
956	sub AnyEvent::Base::Child::DESTROY {	1439	sub AnyEvent::Base::child::DESTROY {
957	my ($pid, $cb) = @{$_[0]};	1440	my ($pid, $cb) = @{$_[0]};
958		1441
959	delete $PID_CB{$pid}{$cb};	1442	delete $PID_CB{$pid}{$cb};
960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1443	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
961		1444
962	undef $CHLD_W unless keys %PID_CB;	1445	undef $CHLD_W unless keys %PID_CB;
963	}	1446	}
964		1447
		1448	# idle emulation is done by simply using a timer, regardless
		1449	# of whether the process is idle or not, and not letting
		1450	# the callback use more than 50% of the time.
		1451	sub idle {
		1452	my (undef, %arg) = @_;
		1453
		1454	my ($cb, $w, $rcb) = $arg{cb};
		1455
		1456	$rcb = sub {
		1457	if ($cb) {
		1458	$w = _time;
		1459	&$cb;
		1460	$w = _time - $w;
		1461
		1462	# never use more then 50% of the time for the idle watcher,
		1463	# within some limits
		1464	$w = 0.0001 if $w < 0.0001;
		1465	$w = 5 if $w > 5;
		1466
		1467	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1468	} else {
		1469	# clean up...
		1470	undef $w;
		1471	undef $rcb;
		1472	}
		1473	};
		1474
		1475	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1476
		1477	bless \\$cb, "AnyEvent::Base::idle"
		1478	}
		1479
		1480	sub AnyEvent::Base::idle::DESTROY {
		1481	undef $${$_[0]};
		1482	}
		1483
965	package AnyEvent::CondVar;	1484	package AnyEvent::CondVar;
966		1485
967	our @ISA = AnyEvent::CondVar::Base::;	1486	our @ISA = AnyEvent::CondVar::Base::;
968		1487
969	package AnyEvent::CondVar::Base;	1488	package AnyEvent::CondVar::Base;
970		1489
971	use overload	1490	#use overload
972	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1491	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
973	fallback => 1;	1492	# fallback => 1;
		1493
		1494	# save 300+ kilobytes by dirtily hardcoding overloading
		1495	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1496	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1497	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1498	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1499
		1500	our $WAITING;
974		1501
975	sub _send {	1502	sub _send {
976	# nop	1503	# nop
977	}	1504	}
978		1505
…		…
991	sub ready {	1518	sub ready {
992	$_[0]{_ae_sent}	1519	$_[0]{_ae_sent}
993	}	1520	}
994		1521
995	sub _wait {	1522	sub _wait {
		1523	$WAITING
		1524	and !$_[0]{_ae_sent}
		1525	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1526
		1527	local $WAITING = 1;
996	AnyEvent->one_event while !$_[0]{_ae_sent};	1528	AnyEvent->one_event while !$_[0]{_ae_sent};
997	}	1529	}
998		1530
999	sub recv {	1531	sub recv {
1000	$_[0]->_wait;	1532	$_[0]->_wait;
…		…
1019	}	1551	}
1020		1552
1021	# undocumented/compatibility with pre-3.4	1553	# undocumented/compatibility with pre-3.4
1022	*broadcast = \&send;	1554	*broadcast = \&send;
1023	*wait = \&_wait;	1555	*wait = \&_wait;
		1556
		1557	=head1 ERROR AND EXCEPTION HANDLING
		1558
		1559	In general, AnyEvent does not do any error handling - it relies on the
		1560	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1561	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1562	checking of all AnyEvent methods, however, which is highly useful during
		1563	development.
		1564
		1565	As for exception handling (i.e. runtime errors and exceptions thrown while
		1566	executing a callback), this is not only highly event-loop specific, but
		1567	also not in any way wrapped by this module, as this is the job of the main
		1568	program.
		1569
		1570	The pure perl event loop simply re-throws the exception (usually
		1571	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1572	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1573	so on.
		1574
		1575	=head1 ENVIRONMENT VARIABLES
		1576
		1577	The following environment variables are used by this module or its
		1578	submodules.
		1579
		1580	Note that AnyEvent will remove I<all> environment variables starting with
		1581	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1582	enabled.
		1583
		1584	=over 4
		1585
		1586	=item C<PERL_ANYEVENT_VERBOSE>
		1587
		1588	By default, AnyEvent will be completely silent except in fatal
		1589	conditions. You can set this environment variable to make AnyEvent more
		1590	talkative.
		1591
		1592	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1593	conditions, such as not being able to load the event model specified by
		1594	C<PERL_ANYEVENT_MODEL>.
		1595
		1596	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1597	model it chooses.
		1598
		1599	When set to C<8> or higher, then AnyEvent will report extra information on
		1600	which optional modules it loads and how it implements certain features.
		1601
		1602	=item C<PERL_ANYEVENT_STRICT>
		1603
		1604	AnyEvent does not do much argument checking by default, as thorough
		1605	argument checking is very costly. Setting this variable to a true value
		1606	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1607	check the arguments passed to most method calls. If it finds any problems,
		1608	it will croak.
		1609
		1610	In other words, enables "strict" mode.
		1611
		1612	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1613	>>, it is definitely recommended to keep it off in production. Keeping
		1614	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1615	can be very useful, however.
		1616
		1617	=item C<PERL_ANYEVENT_MODEL>
		1618
		1619	This can be used to specify the event model to be used by AnyEvent, before
		1620	auto detection and -probing kicks in. It must be a string consisting
		1621	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1622	and the resulting module name is loaded and if the load was successful,
		1623	used as event model. If it fails to load AnyEvent will proceed with
		1624	auto detection and -probing.
		1625
		1626	This functionality might change in future versions.
		1627
		1628	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1629	could start your program like this:
		1630
		1631	PERL_ANYEVENT_MODEL=Perl perl ...
		1632
		1633	=item C<PERL_ANYEVENT_PROTOCOLS>
		1634
		1635	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1636	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1637	of auto probing).
		1638
		1639	Must be set to a comma-separated list of protocols or address families,
		1640	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1641	used, and preference will be given to protocols mentioned earlier in the
		1642	list.
		1643
		1644	This variable can effectively be used for denial-of-service attacks
		1645	against local programs (e.g. when setuid), although the impact is likely
		1646	small, as the program has to handle conenction and other failures anyways.
		1647
		1648	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1649	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1650	- only support IPv4, never try to resolve or contact IPv6
		1651	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1652	IPv6, but prefer IPv6 over IPv4.
		1653
		1654	=item C<PERL_ANYEVENT_EDNS0>
		1655
		1656	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1657	for DNS. This extension is generally useful to reduce DNS traffic, but
		1658	some (broken) firewalls drop such DNS packets, which is why it is off by
		1659	default.
		1660
		1661	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1662	EDNS0 in its DNS requests.
		1663
		1664	=item C<PERL_ANYEVENT_MAX_FORKS>
		1665
		1666	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1667	will create in parallel.
		1668
		1669	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1670
		1671	The default value for the C<max_outstanding> parameter for the default DNS
		1672	resolver - this is the maximum number of parallel DNS requests that are
		1673	sent to the DNS server.
		1674
		1675	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1676
		1677	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1678	configuration) in the default resolver. When set to the empty string, no
		1679	default config will be used.
		1680
		1681	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1682
		1683	When neither C<ca_file> nor C<ca_path> was specified during
		1684	L<AnyEvent::TLS> context creation, and either of these environment
		1685	variables exist, they will be used to specify CA certificate locations
		1686	instead of a system-dependent default.
		1687
		1688	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1689
		1690	When these are set to C<1>, then the respective modules are not
		1691	loaded. Mostly good for testing AnyEvent itself.
		1692
		1693	=back
1024		1694
1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1695	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1026		1696
1027	This is an advanced topic that you do not normally need to use AnyEvent in	1697	This is an advanced topic that you do not normally need to use AnyEvent in
1028	a module. This section is only of use to event loop authors who want to	1698	a module. This section is only of use to event loop authors who want to
…		…
1062		1732
1063	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1733	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1064	condition variables: code blocking while waiting for a condition will	1734	condition variables: code blocking while waiting for a condition will
1065	C<die>. This still works with most modules/usages, and blocking calls must	1735	C<die>. This still works with most modules/usages, and blocking calls must
1066	not be done in an interactive application, so it makes sense.	1736	not be done in an interactive application, so it makes sense.
1067
1068	=head1 ENVIRONMENT VARIABLES
1069
1070	The following environment variables are used by this module:
1071
1072	=over 4
1073
1074	=item C<PERL_ANYEVENT_VERBOSE>
1075
1076	By default, AnyEvent will be completely silent except in fatal
1077	conditions. You can set this environment variable to make AnyEvent more
1078	talkative.
1079
1080	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1081	conditions, such as not being able to load the event model specified by
1082	C<PERL_ANYEVENT_MODEL>.
1083
1084	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1085	model it chooses.
1086
1087	=item C<PERL_ANYEVENT_MODEL>
1088
1089	This can be used to specify the event model to be used by AnyEvent, before
1090	auto detection and -probing kicks in. It must be a string consisting
1091	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1092	and the resulting module name is loaded and if the load was successful,
1093	used as event model. If it fails to load AnyEvent will proceed with
1094	auto detection and -probing.
1095
1096	This functionality might change in future versions.
1097
1098	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1099	could start your program like this:
1100
1101	PERL_ANYEVENT_MODEL=Perl perl ...
1102
1103	=item C<PERL_ANYEVENT_PROTOCOLS>
1104
1105	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1106	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1107	of auto probing).
1108
1109	Must be set to a comma-separated list of protocols or address families,
1110	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1111	used, and preference will be given to protocols mentioned earlier in the
1112	list.
1113
1114	This variable can effectively be used for denial-of-service attacks
1115	against local programs (e.g. when setuid), although the impact is likely
1116	small, as the program has to handle connection errors already-
1117
1118	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1119	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1120	- only support IPv4, never try to resolve or contact IPv6
1121	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1122	IPv6, but prefer IPv6 over IPv4.
1123
1124	=item C<PERL_ANYEVENT_EDNS0>
1125
1126	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1127	for DNS. This extension is generally useful to reduce DNS traffic, but
1128	some (broken) firewalls drop such DNS packets, which is why it is off by
1129	default.
1130
1131	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1132	EDNS0 in its DNS requests.
1133
1134	=item C<PERL_ANYEVENT_MAX_FORKS>
1135
1136	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1137	will create in parallel.
1138
1139	=back
1140		1737
1141	=head1 EXAMPLE PROGRAM	1738	=head1 EXAMPLE PROGRAM
1142		1739
1143	The following program uses an I/O watcher to read data from STDIN, a timer	1740	The following program uses an I/O watcher to read data from STDIN, a timer
1144	to display a message once per second, and a condition variable to quit the	1741	to display a message once per second, and a condition variable to quit the
…		…
1338	watcher.	1935	watcher.
1339		1936
1340	=head3 Results	1937	=head3 Results
1341		1938
1342	name watchers bytes create invoke destroy comment	1939	name watchers bytes create invoke destroy comment
1343	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1940	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1344	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1941	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1345	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1942	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1346	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1943	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1347	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1944	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1348	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1945	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1946	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1947	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1349	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1948	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1350	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1949	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1351	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1950	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1352	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1951	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1353		1952
1354	=head3 Discussion	1953	=head3 Discussion
1355		1954
1356	The benchmark does I<not> measure scalability of the event loop very	1955	The benchmark does I<not> measure scalability of the event loop very
1357	well. For example, a select-based event loop (such as the pure perl one)	1956	well. For example, a select-based event loop (such as the pure perl one)
…		…
1382	performance becomes really bad with lots of file descriptors (and few of	1981	performance becomes really bad with lots of file descriptors (and few of
1383	them active), of course, but this was not subject of this benchmark.	1982	them active), of course, but this was not subject of this benchmark.
1384		1983
1385	The C<Event> module has a relatively high setup and callback invocation	1984	The C<Event> module has a relatively high setup and callback invocation
1386	cost, but overall scores in on the third place.	1985	cost, but overall scores in on the third place.
		1986
		1987	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1988	when using its pure perl backend.
1387		1989
1388	C<Glib>'s memory usage is quite a bit higher, but it features a	1990	C<Glib>'s memory usage is quite a bit higher, but it features a
1389	faster callback invocation and overall ends up in the same class as	1991	faster callback invocation and overall ends up in the same class as
1390	C<Event>. However, Glib scales extremely badly, doubling the number of	1992	C<Event>. However, Glib scales extremely badly, doubling the number of
1391	watchers increases the processing time by more than a factor of four,	1993	watchers increases the processing time by more than a factor of four,
…		…
1469	it to another server. This includes deleting the old timeout and creating	2071	it to another server. This includes deleting the old timeout and creating
1470	a new one that moves the timeout into the future.	2072	a new one that moves the timeout into the future.
1471		2073
1472	=head3 Results	2074	=head3 Results
1473		2075
1474	name sockets create request	2076	name sockets create request
1475	EV 20000 69.01 11.16	2077	EV 20000 69.01 11.16
1476	Perl 20000 73.32 35.87	2078	Perl 20000 73.32 35.87
		2079	IOAsync 20000 157.00 98.14 epoll
		2080	IOAsync 20000 159.31 616.06 poll
1477	Event 20000 212.62 257.32	2081	Event 20000 212.62 257.32
1478	Glib 20000 651.16 1896.30	2082	Glib 20000 651.16 1896.30
1479	POE 20000 349.67 12317.24 uses POE::Loop::Event	2083	POE 20000 349.67 12317.24 uses POE::Loop::Event
1480		2084
1481	=head3 Discussion	2085	=head3 Discussion
1482		2086
1483	This benchmark I<does> measure scalability and overall performance of the	2087	This benchmark I<does> measure scalability and overall performance of the
1484	particular event loop.	2088	particular event loop.
…		…
1486	EV is again fastest. Since it is using epoll on my system, the setup time	2090	EV is again fastest. Since it is using epoll on my system, the setup time
1487	is relatively high, though.	2091	is relatively high, though.
1488		2092
1489	Perl surprisingly comes second. It is much faster than the C-based event	2093	Perl surprisingly comes second. It is much faster than the C-based event
1490	loops Event and Glib.	2094	loops Event and Glib.
		2095
		2096	IO::Async performs very well when using its epoll backend, and still quite
		2097	good compared to Glib when using its pure perl backend.
1491		2098
1492	Event suffers from high setup time as well (look at its code and you will	2099	Event suffers from high setup time as well (look at its code and you will
1493	understand why). Callback invocation also has a high overhead compared to	2100	understand why). Callback invocation also has a high overhead compared to
1494	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2101	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1495	uses select or poll in basically all documented configurations.	2102	uses select or poll in basically all documented configurations.
…		…
1558	=item * C-based event loops perform very well with small number of	2165	=item * C-based event loops perform very well with small number of
1559	watchers, as the management overhead dominates.	2166	watchers, as the management overhead dominates.
1560		2167
1561	=back	2168	=back
1562		2169
		2170	=head2 THE IO::Lambda BENCHMARK
		2171
		2172	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2173	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2174	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2175	shouldn't come as a surprise to anybody). As such, the benchmark is
		2176	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2177	very optimal. But how would AnyEvent compare when used without the extra
		2178	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2179
		2180	The benchmark itself creates an echo-server, and then, for 500 times,
		2181	connects to the echo server, sends a line, waits for the reply, and then
		2182	creates the next connection. This is a rather bad benchmark, as it doesn't
		2183	test the efficiency of the framework or much non-blocking I/O, but it is a
		2184	benchmark nevertheless.
		2185
		2186	name runtime
		2187	Lambda/select 0.330 sec
		2188	+ optimized 0.122 sec
		2189	Lambda/AnyEvent 0.327 sec
		2190	+ optimized 0.138 sec
		2191	Raw sockets/select 0.077 sec
		2192	POE/select, components 0.662 sec
		2193	POE/select, raw sockets 0.226 sec
		2194	POE/select, optimized 0.404 sec
		2195
		2196	AnyEvent/select/nb 0.085 sec
		2197	AnyEvent/EV/nb 0.068 sec
		2198	+state machine 0.134 sec
		2199
		2200	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2201	benchmarks actually make blocking connects and use 100% blocking I/O,
		2202	defeating the purpose of an event-based solution. All of the newly
		2203	written AnyEvent benchmarks use 100% non-blocking connects (using
		2204	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2205	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2206	generally require a lot more bookkeeping and event handling than blocking
		2207	connects (which involve a single syscall only).
		2208
		2209	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2210	offers similar expressive power as POE and IO::Lambda, using conventional
		2211	Perl syntax. This means that both the echo server and the client are 100%
		2212	non-blocking, further placing it at a disadvantage.
		2213
		2214	As you can see, the AnyEvent + EV combination even beats the
		2215	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2216	backend easily beats IO::Lambda and POE.
		2217
		2218	And even the 100% non-blocking version written using the high-level (and
		2219	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2220	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2221	in a non-blocking way.
		2222
		2223	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2224	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2225	part of the IO::lambda distribution and were used without any changes.
		2226
		2227
		2228	=head1 SIGNALS
		2229
		2230	AnyEvent currently installs handlers for these signals:
		2231
		2232	=over 4
		2233
		2234	=item SIGCHLD
		2235
		2236	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2237	emulation for event loops that do not support them natively. Also, some
		2238	event loops install a similar handler.
		2239
		2240	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2241	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2242
		2243	=item SIGPIPE
		2244
		2245	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2246	when AnyEvent gets loaded.
		2247
		2248	The rationale for this is that AnyEvent users usually do not really depend
		2249	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2250	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2251	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2252	some random socket.
		2253
		2254	The rationale for installing a no-op handler as opposed to ignoring it is
		2255	that this way, the handler will be restored to defaults on exec.
		2256
		2257	Feel free to install your own handler, or reset it to defaults.
		2258
		2259	=back
		2260
		2261	=cut
		2262
		2263	undef $SIG{CHLD}
		2264	if $SIG{CHLD} eq 'IGNORE';
		2265
		2266	$SIG{PIPE} = sub { }
		2267	unless defined $SIG{PIPE};
		2268
		2269	=head1 RECOMMENDED/OPTIONAL MODULES
		2270
		2271	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2272	it's built-in modules) are required to use it.
		2273
		2274	That does not mean that AnyEvent won't take advantage of some additional
		2275	modules if they are installed.
		2276
		2277	This section epxlains which additional modules will be used, and how they
		2278	affect AnyEvent's operetion.
		2279
		2280	=over 4
		2281
		2282	=item L<Async::Interrupt>
		2283
		2284	This slightly arcane module is used to implement fast signal handling: To
		2285	my knowledge, there is no way to do completely race-free and quick
		2286	signal handling in pure perl. To ensure that signals still get
		2287	delivered, AnyEvent will start an interval timer to wake up perl (and
		2288	catch the signals) with some delay (default is 10 seconds, look for
		2289	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2290
		2291	If this module is available, then it will be used to implement signal
		2292	catching, which means that signals will not be delayed, and the event loop
		2293	will not be interrupted regularly, which is more efficient (And good for
		2294	battery life on laptops).
		2295
		2296	This affects not just the pure-perl event loop, but also other event loops
		2297	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2298
		2299	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2300	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2301	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2302	does nothing for those backends.
		2303
		2304	=item L<EV>
		2305
		2306	This module isn't really "optional", as it is simply one of the backend
		2307	event loops that AnyEvent can use. However, it is simply the best event
		2308	loop available in terms of features, speed and stability: It supports
		2309	the AnyEvent API optimally, implements all the watcher types in XS, does
		2310	automatic timer adjustments even when no monotonic clock is available,
		2311	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2312	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2313	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2314
		2315	=item L<Guard>
		2316
		2317	The guard module, when used, will be used to implement
		2318	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2319	lot less memory), but otherwise doesn't affect guard operation much. It is
		2320	purely used for performance.
		2321
		2322	=item L<JSON> and L<JSON::XS>
		2323
		2324	This module is required when you want to read or write JSON data via
		2325	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2326	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2327
		2328	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2329	installed.
		2330
		2331	=item L<Net::SSLeay>
		2332
		2333	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2334	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2335	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2336
		2337	=item L<Time::HiRes>
		2338
		2339	This module is part of perl since release 5.008. It will be used when the
		2340	chosen event library does not come with a timing source on it's own. The
		2341	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2342	try to use a monotonic clock for timing stability.
		2343
		2344	=back
		2345
1563		2346
1564	=head1 FORK	2347	=head1 FORK
1565		2348
1566	Most event libraries are not fork-safe. The ones who are usually are	2349	Most event libraries are not fork-safe. The ones who are usually are
1567	because they rely on inefficient but fork-safe C<select> or C<poll>	2350	because they rely on inefficient but fork-safe C<select> or C<poll>
1568	calls. Only L<EV> is fully fork-aware.	2351	calls. Only L<EV> is fully fork-aware.
1569		2352
1570	If you have to fork, you must either do so I<before> creating your first	2353	If you have to fork, you must either do so I<before> creating your first
1571	watcher OR you must not use AnyEvent at all in the child.	2354	watcher OR you must not use AnyEvent at all in the child OR you must do
		2355	something completely out of the scope of AnyEvent.
1572		2356
1573		2357
1574	=head1 SECURITY CONSIDERATIONS	2358	=head1 SECURITY CONSIDERATIONS
1575		2359
1576	AnyEvent can be forced to load any event model via	2360	AnyEvent can be forced to load any event model via
…		…
1581	specified in the variable.	2365	specified in the variable.
1582		2366
1583	You can make AnyEvent completely ignore this variable by deleting it	2367	You can make AnyEvent completely ignore this variable by deleting it
1584	before the first watcher gets created, e.g. with a C<BEGIN> block:	2368	before the first watcher gets created, e.g. with a C<BEGIN> block:
1585		2369
1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2370	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1587		2371
1588	use AnyEvent;	2372	use AnyEvent;
1589		2373
1590	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2374	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1591	be used to probe what backend is used and gain other information (which is	2375	be used to probe what backend is used and gain other information (which is
1592	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2376	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2377	$ENV{PERL_ANYEVENT_STRICT}.
		2378
		2379	Note that AnyEvent will remove I<all> environment variables starting with
		2380	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2381	enabled.
		2382
		2383
		2384	=head1 BUGS
		2385
		2386	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2387	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2388	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2389	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2390	pronounced).
1593		2391
1594		2392
1595	=head1 SEE ALSO	2393	=head1 SEE ALSO
1596		2394
1597	Utility functions: L<AnyEvent::Util>.	2395	Utility functions: L<AnyEvent::Util>.
…		…
1600	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2398	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1601		2399
1602	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2400	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1603	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2401	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1604	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2402	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1605	L<AnyEvent::Impl::POE>.	2403	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1606		2404
1607	Non-blocking file handles, sockets, TCP clients and	2405	Non-blocking file handles, sockets, TCP clients and
1608	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2406	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1609		2407
1610	Asynchronous DNS: L<AnyEvent::DNS>.	2408	Asynchronous DNS: L<AnyEvent::DNS>.
1611		2409
1612	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2410	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2411	L<Coro::Event>,
1613		2412
1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2413	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2414	L<AnyEvent::HTTP>.
1615		2415
1616		2416
1617	=head1 AUTHOR	2417	=head1 AUTHOR
1618		2418
1619	Marc Lehmann <schmorp@schmorp.de>	2419	Marc Lehmann <schmorp@schmorp.de>
1620	http://home.schmorp.de/	2420	http://home.schmorp.de/
1621		2421
1622	=cut	2422	=cut
1623		2423
1624	1	2424	1
1625		2425

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