ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs.
Revision 1.265 by root, Wed Jul 29 13:10:58 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# 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	Repository>, 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 (one some backends,
268	watches for any child process exit). The watcher will trigger as often	406	using C<0> watches for any child process exit, on others this will
269	as status change for the child are received. This works by installing a	407	croak). The watcher will be triggered only when the child process has
270	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	finished and an exit status is available, not on any trace events
271	and exit status (as returned by waitpid), so unlike other watcher types,	409	(stopped/continued).
272	you I<can> rely on child watcher callback arguments.	410
		411	The callback will be called with the pid and exit status (as returned by
		412	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		413	callback arguments.
		414
		415	This watcher type works by installing a signal handler for C<SIGCHLD>,
		416	and since it cannot be shared, nothing else should use SIGCHLD or reap
		417	random child processes (waiting for specific child processes, e.g. inside
		418	C<system>, is just fine).
273		419
274	There is a slight catch to child watchers, however: you usually start them	420	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	421	I<after> the child process was created, and this means the process could
276	have exited already (and no SIGCHLD will be sent anymore).	422	have exited already (and no SIGCHLD will be sent anymore).
277		423
278	Not all event models handle this correctly (POE doesn't), but even for	424	Not all event models handle this correctly (neither POE nor IO::Async do,
		425	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	426	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).	427	the process exits (i.e. before you fork in the first place). AnyEvent's
		428	pure perl event loop handles all cases correctly regardless of when you
		429	start the watcher.
281		430
282	This means you cannot create a child watcher as the very first thing in an	431	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	432	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>).	433	watcher before you C<fork> the child (alternatively, you can call
		434	C<AnyEvent::detect>).
		435
		436	As most event loops do not support waiting for child events, they will be
		437	emulated by AnyEvent in most cases, in which the latency and race problems
		438	mentioned in the description of signal watchers apply.
285		439
286	Example: fork a process and wait for it	440	Example: fork a process and wait for it
287		441
288	my $done = AnyEvent->condvar;	442	my $done = AnyEvent->condvar;
289		443
290	my $pid = fork or exit 5;	444	my $pid = fork or exit 5;
291		445
292	my $w = AnyEvent->child (	446	my $w = AnyEvent->child (
293	pid => $pid,	447	pid => $pid,
294	cb => sub {	448	cb => sub {
295	my ($pid, $status) = @_;	449	my ($pid, $status) = @_;
296	warn "pid $pid exited with status $status";	450	warn "pid $pid exited with status $status";
297	$done->send;	451	$done->send;
298	},	452	},
299	);	453	);
300		454
301	# do something else, then wait for process exit	455	# do something else, then wait for process exit
302	$done->recv;	456	$done->recv;
		457
		458	=head2 IDLE WATCHERS
		459
		460	Sometimes there is a need to do something, but it is not so important
		461	to do it instantly, but only when there is nothing better to do. This
		462	"nothing better to do" is usually defined to be "no other events need
		463	attention by the event loop".
		464
		465	Idle watchers ideally get invoked when the event loop has nothing
		466	better to do, just before it would block the process to wait for new
		467	events. Instead of blocking, the idle watcher is invoked.
		468
		469	Most event loops unfortunately do not really support idle watchers (only
		470	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		471	will simply call the callback "from time to time".
		472
		473	Example: read lines from STDIN, but only process them when the
		474	program is otherwise idle:
		475
		476	my @lines; # read data
		477	my $idle_w;
		478	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		479	push @lines, scalar <STDIN>;
		480
		481	# start an idle watcher, if not already done
		482	$idle_w ||= AnyEvent->idle (cb => sub {
		483	# handle only one line, when there are lines left
		484	if (my $line = shift @lines) {
		485	print "handled when idle: $line";
		486	} else {
		487	# otherwise disable the idle watcher again
		488	undef $idle_w;
		489	}
		490	});
		491	});
303		492
304	=head2 CONDITION VARIABLES	493	=head2 CONDITION VARIABLES
305		494
306	If you are familiar with some event loops you will know that all of them	495	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	496	require you to run some blocking "loop", "run" or similar function that
308	will actively watch for new events and call your callbacks.	497	will actively watch for new events and call your callbacks.
309		498
310	AnyEvent is different, it expects somebody else to run the event loop and	499	AnyEvent is slightly different: it expects somebody else to run the event
311	will only block when necessary (usually when told by the user).	500	loop and will only block when necessary (usually when told by the user).
312		501
313	The instrument to do that is called a "condition variable", so called	502	The instrument to do that is called a "condition variable", so called
314	because they represent a condition that must become true.	503	because they represent a condition that must become true.
		504
		505	Now is probably a good time to look at the examples further below.
315		506
316	Condition variables can be created by calling the C<< AnyEvent->condvar	507	Condition variables can be created by calling the C<< AnyEvent->condvar
317	>> method, usually without arguments. The only argument pair allowed is	508	>> method, usually without arguments. The only argument pair allowed is
318	C<cb>, which specifies a callback to be called when the condition variable	509	C<cb>, which specifies a callback to be called when the condition variable
319	becomes true.	510	becomes true, with the condition variable as the first argument (but not
		511	the results).
320		512
321	After creation, the condition variable is "false" until it becomes "true"	513	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	514	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<<	515	were a callback, read about the caveats in the description for the C<<
324	->send >> method).	516	->send >> method).
…		…
326	Condition variables are similar to callbacks, except that you can	518	Condition variables are similar to callbacks, except that you can
327	optionally wait for them. They can also be called merge points - points	519	optionally wait for them. They can also be called merge points - points
328	in time where multiple outstanding events have been processed. And yet	520	in time where multiple outstanding events have been processed. And yet
329	another way to call them is transactions - each condition variable can be	521	another way to call them is transactions - each condition variable can be
330	used to represent a transaction, which finishes at some point and delivers	522	used to represent a transaction, which finishes at some point and delivers
331	a result.	523	a result. And yet some people know them as "futures" - a promise to
		524	compute/deliver something that you can wait for.
332		525
333	Condition variables are very useful to signal that something has finished,	526	Condition variables are very useful to signal that something has finished,
334	for example, if you write a module that does asynchronous http requests,	527	for example, if you write a module that does asynchronous http requests,
335	then a condition variable would be the ideal candidate to signal the	528	then a condition variable would be the ideal candidate to signal the
336	availability of results. The user can either act when the callback is	529	availability of results. The user can either act when the callback is
…		…
370	after => 1,	563	after => 1,
371	cb => sub { $result_ready->send },	564	cb => sub { $result_ready->send },
372	);	565	);
373		566
374	# this "blocks" (while handling events) till the callback	567	# this "blocks" (while handling events) till the callback
375	# calls send	568	# calls -<send
376	$result_ready->recv;	569	$result_ready->recv;
377		570
378	Example: wait for a timer, but take advantage of the fact that	571	Example: wait for a timer, but take advantage of the fact that condition
379	condition variables are also code references.	572	variables are also callable directly.
380		573
381	my $done = AnyEvent->condvar;	574	my $done = AnyEvent->condvar;
382	my $delay = AnyEvent->timer (after => 5, cb => $done);	575	my $delay = AnyEvent->timer (after => 5, cb => $done);
383	$done->recv;	576	$done->recv;
		577
		578	Example: Imagine an API that returns a condvar and doesn't support
		579	callbacks. This is how you make a synchronous call, for example from
		580	the main program:
		581
		582	use AnyEvent::CouchDB;
		583
		584	...
		585
		586	my @info = $couchdb->info->recv;
		587
		588	And this is how you would just set a callback to be called whenever the
		589	results are available:
		590
		591	$couchdb->info->cb (sub {
		592	my @info = $_[0]->recv;
		593	});
384		594
385	=head3 METHODS FOR PRODUCERS	595	=head3 METHODS FOR PRODUCERS
386		596
387	These methods should only be used by the producing side, i.e. the	597	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	598	code/module that eventually sends the signal. Note that it is also
…		…
401	immediately from within send.	611	immediately from within send.
402		612
403	Any arguments passed to the C<send> call will be returned by all	613	Any arguments passed to the C<send> call will be returned by all
404	future C<< ->recv >> calls.	614	future C<< ->recv >> calls.
405		615
406	Condition variables are overloaded so one can call them directly	616	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	617	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	618	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		619
415	=item $cv->croak ($error)	620	=item $cv->croak ($error)
416		621
417	Similar to send, but causes all call's to C<< ->recv >> to invoke	622	Similar to send, but causes all call's to C<< ->recv >> to invoke
418	C<Carp::croak> with the given error message/object/scalar.	623	C<Carp::croak> with the given error message/object/scalar.
419		624
420	This can be used to signal any errors to the condition variable	625	This can be used to signal any errors to the condition variable
421	user/consumer.	626	user/consumer. Doing it this way instead of calling C<croak> directly
		627	delays the error detetcion, but has the overwhelmign advantage that it
		628	diagnoses the error at the place where the result is expected, and not
		629	deep in some event clalback without connection to the actual code causing
		630	the problem.
422		631
423	=item $cv->begin ([group callback])	632	=item $cv->begin ([group callback])
424		633
425	=item $cv->end	634	=item $cv->end
426
427	These two methods are EXPERIMENTAL and MIGHT CHANGE.
428		635
429	These two methods can be used to combine many transactions/events into	636	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	637	one. For example, a function that pings many hosts in parallel might want
431	to use a condition variable for the whole process.	638	to use a condition variable for the whole process.
432		639
…		…
434	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	641	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	642	>>, 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	643	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.	644	callback was set, C<send> will be called without any arguments.
438		645
439	Let's clarify this with the ping example:	646	You can think of C<< $cv->send >> giving you an OR condition (one call
		647	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		648	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		649
		650	Let's start with a simple example: you have two I/O watchers (for example,
		651	STDOUT and STDERR for a program), and you want to wait for both streams to
		652	close before activating a condvar:
		653
		654	my $cv = AnyEvent->condvar;
		655
		656	$cv->begin; # first watcher
		657	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		658	defined sysread $fh1, my $buf, 4096
		659	or $cv->end;
		660	});
		661
		662	$cv->begin; # second watcher
		663	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		664	defined sysread $fh2, my $buf, 4096
		665	or $cv->end;
		666	});
		667
		668	$cv->recv;
		669
		670	This works because for every event source (EOF on file handle), there is
		671	one call to C<begin>, so the condvar waits for all calls to C<end> before
		672	sending.
		673
		674	The ping example mentioned above is slightly more complicated, as the
		675	there are results to be passwd back, and the number of tasks that are
		676	begung can potentially be zero:
440		677
441	my $cv = AnyEvent->condvar;	678	my $cv = AnyEvent->condvar;
442		679
443	my %result;	680	my %result;
444	$cv->begin (sub { $cv->send (\%result) });	681	$cv->begin (sub { $cv->send (\%result) });
…		…
464	loop, which serves two important purposes: first, it sets the callback	701	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	702	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	703	C<send> is called even when C<no> hosts are being pinged (the loop
467	doesn't execute once).	704	doesn't execute once).
468		705
469	This is the general pattern when you "fan out" into multiple subrequests:	706	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>	707	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	708	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>.	709	subrequest you start, call C<begin> and for each subrequest you finish,
		710	call C<end>.
473		711
474	=back	712	=back
475		713
476	=head3 METHODS FOR CONSUMERS	714	=head3 METHODS FOR CONSUMERS
477		715
…		…
493	function will call C<croak>.	731	function will call C<croak>.
494		732
495	In list context, all parameters passed to C<send> will be returned,	733	In list context, all parameters passed to C<send> will be returned,
496	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
497		735
		736	Note that doing a blocking wait in a callback is not supported by any
		737	event loop, that is, recursive invocation of a blocking C<< ->recv
		738	>> is not allowed, and the C<recv> call will C<croak> if such a
		739	condition is detected. This condition can be slightly loosened by using
		740	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		741	any thread that doesn't run the event loop itself.
		742
498	Not all event models support a blocking wait - some die in that case	743	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	744	(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	745	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	746	caller decide whether the call will block or not (for example, by coupling
502	condition variables with some kind of request results and supporting	747	condition variables with some kind of request results and supporting
503	callbacks so the caller knows that getting the result will not block,	748	callbacks so the caller knows that getting the result will not block,
504	while still supporting blocking waits if the caller so desires).	749	while still supporting blocking waits if the caller so desires).
505		750
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	751	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	752	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	753	time). This will work even when the event loop does not support blocking
520	waits otherwise.	754	waits otherwise.
521		755
522	=item $bool = $cv->ready	756	=item $bool = $cv->ready
523		757
524	Returns true when the condition is "true", i.e. whether C<send> or	758	Returns true when the condition is "true", i.e. whether C<send> or
525	C<croak> have been called.	759	C<croak> have been called.
526		760
527	=item $cb = $cv->cb ([new callback])	761	=item $cb = $cv->cb ($cb->($cv))
528		762
529	This is a mutator function that returns the callback set and optionally	763	This is a mutator function that returns the callback set and optionally
530	replaces it before doing so.	764	replaces it before doing so.
531		765
532	The callback will be called when the condition becomes "true", i.e. when	766	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	767	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.	768	variable itself. Calling C<recv> inside the callback or at any later time
		769	is guaranteed not to block.
535		770
536	=back	771	=back
537		772
		773	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		774
		775	The available backend classes are (every class has its own manpage):
		776
		777	=over 4
		778
		779	=item Backends that are autoprobed when no other event loop can be found.
		780
		781	EV is the preferred backend when no other event loop seems to be in
		782	use. If EV is not installed, then AnyEvent will try Event, and, failing
		783	that, will fall back to its own pure-perl implementation, which is
		784	available everywhere as it comes with AnyEvent itself.
		785
		786	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		787	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		788	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		789
		790	=item Backends that are transparently being picked up when they are used.
		791
		792	These will be used when they are currently loaded when the first watcher
		793	is created, in which case it is assumed that the application is using
		794	them. This means that AnyEvent will automatically pick the right backend
		795	when the main program loads an event module before anything starts to
		796	create watchers. Nothing special needs to be done by the main program.
		797
		798	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		799	AnyEvent::Impl::Tk based on Tk, very broken.
		800	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		801	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		802	AnyEvent::Impl::Irssi used when running within irssi.
		803
		804	=item Backends with special needs.
		805
		806	Qt requires the Qt::Application to be instantiated first, but will
		807	otherwise be picked up automatically. As long as the main program
		808	instantiates the application before any AnyEvent watchers are created,
		809	everything should just work.
		810
		811	AnyEvent::Impl::Qt based on Qt.
		812
		813	Support for IO::Async can only be partial, as it is too broken and
		814	architecturally limited to even support the AnyEvent API. It also
		815	is the only event loop that needs the loop to be set explicitly, so
		816	it can only be used by a main program knowing about AnyEvent. See
		817	L<AnyEvent::Impl::Async> for the gory details.
		818
		819	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		820
		821	=item Event loops that are indirectly supported via other backends.
		822
		823	Some event loops can be supported via other modules:
		824
		825	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		826
		827	B<WxWidgets> has no support for watching file handles. However, you can
		828	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		829	polls 20 times per second, which was considered to be too horrible to even
		830	consider for AnyEvent.
		831
		832	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		833	backend, so it can be supported through POE.
		834
		835	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		836	load L<POE> when detecting them, in the hope that POE will pick them up,
		837	in which case everything will be automatic.
		838
		839	=back
		840
538	=head1 GLOBAL VARIABLES AND FUNCTIONS	841	=head1 GLOBAL VARIABLES AND FUNCTIONS
539		842
		843	These are not normally required to use AnyEvent, but can be useful to
		844	write AnyEvent extension modules.
		845
540	=over 4	846	=over 4
541		847
542	=item $AnyEvent::MODEL	848	=item $AnyEvent::MODEL
543		849
544	Contains C<undef> until the first watcher is being created. Then it	850	Contains C<undef> until the first watcher is being created, before the
		851	backend has been autodetected.
		852
545	contains the event model that is being used, which is the name of the	853	Afterwards it contains the event model that is being used, which is the
546	Perl class implementing the model. This class is usually one of the	854	name of the Perl class implementing the model. This class is usually one
547	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	855	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
548	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	856	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
549		857	will be C<urxvt::anyevent>).
550	The known classes so far are:
551
552	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
553	AnyEvent::Impl::Event based on Event, second best choice.
554	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
555	AnyEvent::Impl::Glib based on Glib, third-best choice.
556	AnyEvent::Impl::Tk based on Tk, very bad choice.
557	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
558	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
559	AnyEvent::Impl::POE based on POE, not generic enough for full support.
560
561	There is no support for WxWidgets, as WxWidgets has no support for
562	watching file handles. However, you can use WxWidgets through the
563	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
564	second, which was considered to be too horrible to even consider for
565	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
566	it's adaptor.
567
568	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
569	autodetecting them.
570		858
571	=item AnyEvent::detect	859	=item AnyEvent::detect
572		860
573	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	861	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
574	if necessary. You should only call this function right before you would	862	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	863	have created an AnyEvent watcher anyway, that is, as late as possible at
576	runtime.	864	runtime, and not e.g. while initialising of your module.
		865
		866	If you need to do some initialisation before AnyEvent watchers are
		867	created, use C<post_detect>.
577		868
578	=item $guard = AnyEvent::post_detect { BLOCK }	869	=item $guard = AnyEvent::post_detect { BLOCK }
579		870
580	Arranges for the code block to be executed as soon as the event model is	871	Arranges for the code block to be executed as soon as the event model is
581	autodetected (or immediately if this has already happened).	872	autodetected (or immediately if this has already happened).
582		873
		874	The block will be executed I<after> the actual backend has been detected
		875	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		876	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		877	other initialisations - see the sources of L<AnyEvent::Strict> or
		878	L<AnyEvent::AIO> to see how this is used.
		879
		880	The most common usage is to create some global watchers, without forcing
		881	event module detection too early, for example, L<AnyEvent::AIO> creates
		882	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		883	avoid autodetecting the event module at load time.
		884
583	If called in scalar or list context, then it creates and returns an object	885	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	886	that automatically removes the callback again when it is destroyed (or
		887	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
585	L<Coro::BDB> for a case where this is useful.	888	a case where this is useful.
		889
		890	Example: Create a watcher for the IO::AIO module and store it in
		891	C<$WATCHER>. Only do so after the event loop is initialised, though.
		892
		893	our WATCHER;
		894
		895	my $guard = AnyEvent::post_detect {
		896	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		897	};
		898
		899	# the ||= is important in case post_detect immediately runs the block,
		900	# as to not clobber the newly-created watcher. assigning both watcher and
		901	# post_detect guard to the same variable has the advantage of users being
		902	# able to just C<undef $WATCHER> if the watcher causes them grief.
		903
		904	$WATCHER ||= $guard;
586		905
587	=item @AnyEvent::post_detect	906	=item @AnyEvent::post_detect
588		907
589	If there are any code references in this array (you can C<push> to it	908	If there are any code references in this array (you can C<push> to it
590	before or after loading AnyEvent), then they will called directly after	909	before or after loading AnyEvent), then they will called directly after
591	the event loop has been chosen.	910	the event loop has been chosen.
592		911
593	You should check C<$AnyEvent::MODEL> before adding to this array, though:	912	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,	913	if it is defined then the event loop has already been detected, and the
595	and the array will be ignored.	914	array will be ignored.
596		915
597	Best use C<AnyEvent::post_detect { BLOCK }> instead.	916	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		917	it,as it takes care of these details.
		918
		919	This variable is mainly useful for modules that can do something useful
		920	when AnyEvent is used and thus want to know when it is initialised, but do
		921	not need to even load it by default. This array provides the means to hook
		922	into AnyEvent passively, without loading it.
598		923
599	=back	924	=back
600		925
601	=head1 WHAT TO DO IN A MODULE	926	=head1 WHAT TO DO IN A MODULE
602		927
…		…
657		982
658		983
659	=head1 OTHER MODULES	984	=head1 OTHER MODULES
660		985
661	The following is a non-exhaustive list of additional modules that use	986	The following is a non-exhaustive list of additional modules that use
662	AnyEvent and can therefore be mixed easily with other AnyEvent modules	987	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	988	modules and other event loops in the same program. Some of the modules
664	available via CPAN.	989	come with AnyEvent, most are available via CPAN.
665		990
666	=over 4	991	=over 4
667		992
668	=item L<AnyEvent::Util>	993	=item L<AnyEvent::Util>
669		994
670	Contains various utility functions that replace often-used but blocking	995	Contains various utility functions that replace often-used but blocking
671	functions such as C<inet_aton> by event-/callback-based versions.	996	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		997
677	=item L<AnyEvent::Socket>	998	=item L<AnyEvent::Socket>
678		999
679	Provides various utility functions for (internet protocol) sockets,	1000	Provides various utility functions for (internet protocol) sockets,
680	addresses and name resolution. Also functions to create non-blocking tcp	1001	addresses and name resolution. Also functions to create non-blocking tcp
681	connections or tcp servers, with IPv6 and SRV record support and more.	1002	connections or tcp servers, with IPv6 and SRV record support and more.
682		1003
		1004	=item L<AnyEvent::Handle>
		1005
		1006	Provide read and write buffers, manages watchers for reads and writes,
		1007	supports raw and formatted I/O, I/O queued and fully transparent and
		1008	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1009
683	=item L<AnyEvent::DNS>	1010	=item L<AnyEvent::DNS>
684		1011
685	Provides rich asynchronous DNS resolver capabilities.	1012	Provides rich asynchronous DNS resolver capabilities.
686		1013
		1014	=item L<AnyEvent::HTTP>
		1015
		1016	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1017	HTTP requests.
		1018
687	=item L<AnyEvent::HTTPD>	1019	=item L<AnyEvent::HTTPD>
688		1020
689	Provides a simple web application server framework.	1021	Provides a simple web application server framework.
690		1022
691	=item L<AnyEvent::FastPing>	1023	=item L<AnyEvent::FastPing>
692		1024
693	The fastest ping in the west.	1025	The fastest ping in the west.
694		1026
		1027	=item L<AnyEvent::DBI>
		1028
		1029	Executes L<DBI> requests asynchronously in a proxy process.
		1030
		1031	=item L<AnyEvent::AIO>
		1032
		1033	Truly asynchronous I/O, should be in the toolbox of every event
		1034	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1035	together.
		1036
		1037	=item L<AnyEvent::BDB>
		1038
		1039	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1040	L<BDB> and AnyEvent together.
		1041
		1042	=item L<AnyEvent::GPSD>
		1043
		1044	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1045
695	=item L<Net::IRC3>	1046	=item L<AnyEvent::IRC>
696		1047
697	AnyEvent based IRC client module family.	1048	AnyEvent based IRC client module family (replacing the older Net::IRC3).
698		1049
699	=item L<Net::XMPP2>	1050	=item L<AnyEvent::XMPP>
700		1051
701	AnyEvent based XMPP (Jabber protocol) module family.	1052	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1053	Net::XMPP2>.
		1054
		1055	=item L<AnyEvent::IGS>
		1056
		1057	A non-blocking interface to the Internet Go Server protocol (used by
		1058	L<App::IGS>).
702		1059
703	=item L<Net::FCP>	1060	=item L<Net::FCP>
704		1061
705	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1062	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
706	of AnyEvent.	1063	of AnyEvent.
…		…
711		1068
712	=item L<Coro>	1069	=item L<Coro>
713		1070
714	Has special support for AnyEvent via L<Coro::AnyEvent>.	1071	Has special support for AnyEvent via L<Coro::AnyEvent>.
715		1072
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	1073	=back
732		1074
733	=cut	1075	=cut
734		1076
735	package AnyEvent;	1077	package AnyEvent;
736		1078
		1079	# basically a tuned-down version of common::sense
		1080	sub common_sense {
737	no warnings;	1081	# no warnings
738	use strict;	1082	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1083	# use strict vars subs
		1084	$^H |= 0x00000600;
		1085	}
739		1086
		1087	BEGIN { AnyEvent::common_sense }
		1088
740	use Carp;	1089	use Carp ();
741		1090
742	our $VERSION = '4.05';	1091	our $VERSION = 4.881;
743	our $MODEL;	1092	our $MODEL;
744		1093
745	our $AUTOLOAD;	1094	our $AUTOLOAD;
746	our @ISA;	1095	our @ISA;
747		1096
748	our @REGISTRY;	1097	our @REGISTRY;
749		1098
750	our $WIN32;	1099	our $WIN32;
751		1100
		1101	our $VERBOSE;
		1102
752	BEGIN {	1103	BEGIN {
753	my $win32 = ! ! ($^O =~ /mswin32/i);	1104	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
754	eval "sub WIN32(){ $win32 }";	1105	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
755	}
756		1106
		1107	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1108	if ${^TAINT};
		1109
757	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1110	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1111
		1112	}
		1113
		1114	our $MAX_SIGNAL_LATENCY = 10;
758		1115
759	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1116	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
760		1117
761	{	1118	{
762	my $idx;	1119	my $idx;
…		…
764	for reverse split /\s*,\s*/,	1121	for reverse split /\s*,\s*/,
765	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1122	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
766	}	1123	}
767		1124
768	my @models = (	1125	my @models = (
769	[EV:: => AnyEvent::Impl::EV::],	1126	[EV:: => AnyEvent::Impl::EV:: , 1],
770	[Event:: => AnyEvent::Impl::Event::],	1127	[Event:: => AnyEvent::Impl::Event::, 1],
771	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1128	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
772	# everything below here will not be autoprobed	1129	# everything below here will not (normally) be autoprobed
773	# as the pureperl backend should work everywhere	1130	# as the pureperl backend should work everywhere
774	# and is usually faster	1131	# and is usually faster
		1132	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1133	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1134	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
775	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1135	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
776	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
777	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
778	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1136	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1137	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
780	[Wx:: => AnyEvent::Impl::POE::],	1138	[Wx:: => AnyEvent::Impl::POE::],
781	[Prima:: => AnyEvent::Impl::POE::],	1139	[Prima:: => AnyEvent::Impl::POE::],
		1140	# IO::Async is just too broken - we would need workarounds for its
		1141	# byzantine signal and broken child handling, among others.
		1142	# IO::Async is rather hard to detect, as it doesn't have any
		1143	# obvious default class.
		1144	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1145	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1146	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
782	);	1147	);
783		1148
784	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1149	our %method = map +($_ => 1),
		1150	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
785		1151
786	our @post_detect;	1152	our @post_detect;
787		1153
788	sub post_detect(&) {	1154	sub post_detect(&) {
789	my ($cb) = @_;	1155	my ($cb) = @_;
790		1156
791	if ($MODEL) {	1157	if ($MODEL) {
792	$cb->();	1158	$cb->();
793		1159
794	1	1160	undef
795	} else {	1161	} else {
796	push @post_detect, $cb;	1162	push @post_detect, $cb;
797		1163
798	defined wantarray	1164	defined wantarray
799	? bless \$cb, "AnyEvent::Util::PostDetect"	1165	? bless \$cb, "AnyEvent::Util::postdetect"
800	: ()	1166	: ()
801	}	1167	}
802	}	1168	}
803		1169
804	sub AnyEvent::Util::PostDetect::DESTROY {	1170	sub AnyEvent::Util::postdetect::DESTROY {
805	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1171	@post_detect = grep $_ != ${$_[0]}, @post_detect;
806	}	1172	}
807		1173
808	sub detect() {	1174	sub detect() {
809	unless ($MODEL) {	1175	unless ($MODEL) {
810	no strict 'refs';
811	local $SIG{__DIE__};	1176	local $SIG{__DIE__};
812		1177
813	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1178	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
814	my $model = "AnyEvent::Impl::$1";	1179	my $model = "AnyEvent::Impl::$1";
815	if (eval "require $model") {	1180	if (eval "require $model") {
816	$MODEL = $model;	1181	$MODEL = $model;
817	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1182	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
818	} else {	1183	} else {
819	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1184	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
820	}	1185	}
821	}	1186	}
822		1187
823	# check for already loaded models	1188	# check for already loaded models
824	unless ($MODEL) {	1189	unless ($MODEL) {
825	for (@REGISTRY, @models) {	1190	for (@REGISTRY, @models) {
826	my ($package, $model) = @$_;	1191	my ($package, $model) = @$_;
827	if (${"$package\::VERSION"} > 0) {	1192	if (${"$package\::VERSION"} > 0) {
828	if (eval "require $model") {	1193	if (eval "require $model") {
829	$MODEL = $model;	1194	$MODEL = $model;
830	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1195	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
831	last;	1196	last;
832	}	1197	}
833	}	1198	}
834	}	1199	}
835		1200
836	unless ($MODEL) {	1201	unless ($MODEL) {
837	# try to load a model	1202	# try to autoload a model
838
839	for (@REGISTRY, @models) {	1203	for (@REGISTRY, @models) {
840	my ($package, $model) = @$_;	1204	my ($package, $model, $autoload) = @$_;
		1205	if (
		1206	$autoload
841	if (eval "require $package"	1207	and eval "require $package"
842	and ${"$package\::VERSION"} > 0	1208	and ${"$package\::VERSION"} > 0
843	and eval "require $model") {	1209	and eval "require $model"
		1210	) {
844	$MODEL = $model;	1211	$MODEL = $model;
845	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1212	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
846	last;	1213	last;
847	}	1214	}
848	}	1215	}
849		1216
850	$MODEL	1217	$MODEL
851	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1218	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
852	}	1219	}
853	}	1220	}
854		1221
		1222	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1223
855	unshift @ISA, $MODEL;	1224	unshift @ISA, $MODEL;
856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1225
		1226	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
857		1227
858	(shift @post_detect)->() while @post_detect;	1228	(shift @post_detect)->() while @post_detect;
859	}	1229	}
860		1230
861	$MODEL	1231	$MODEL
…		…
863		1233
864	sub AUTOLOAD {	1234	sub AUTOLOAD {
865	(my $func = $AUTOLOAD) =~ s/.*://;	1235	(my $func = $AUTOLOAD) =~ s/.*://;
866		1236
867	$method{$func}	1237	$method{$func}
868	or croak "$func: not a valid method for AnyEvent objects";	1238	or Carp::croak "$func: not a valid method for AnyEvent objects";
869		1239
870	detect unless $MODEL;	1240	detect unless $MODEL;
871		1241
872	my $class = shift;	1242	my $class = shift;
873	$class->$func (@_);	1243	$class->$func (@_);
874	}	1244	}
875		1245
		1246	# utility function to dup a filehandle. this is used by many backends
		1247	# to support binding more than one watcher per filehandle (they usually
		1248	# allow only one watcher per fd, so we dup it to get a different one).
		1249	sub _dupfh($$;$$) {
		1250	my ($poll, $fh, $r, $w) = @_;
		1251
		1252	# cygwin requires the fh mode to be matching, unix doesn't
		1253	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1254
		1255	open my $fh2, $mode, $fh
		1256	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1257
		1258	# we assume CLOEXEC is already set by perl in all important cases
		1259
		1260	($fh2, $rw)
		1261	}
		1262
876	package AnyEvent::Base;	1263	package AnyEvent::Base;
877		1264
		1265	# default implementations for many methods
		1266
		1267	sub _time {
		1268	# probe for availability of Time::HiRes
		1269	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1270	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1271	*_time = \&Time::HiRes::time;
		1272	# if (eval "use POSIX (); (POSIX::times())...
		1273	} else {
		1274	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1275	*_time = sub { time }; # epic fail
		1276	}
		1277
		1278	&_time
		1279	}
		1280
		1281	sub time { _time }
		1282	sub now { _time }
		1283	sub now_update { }
		1284
878	# default implementation for ->condvar	1285	# default implementation for ->condvar
879		1286
880	sub condvar {	1287	sub condvar {
881	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1288	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
882	}	1289	}
883		1290
884	# default implementation for ->signal	1291	# default implementation for ->signal
885		1292
886	our %SIG_CB;	1293	our $HAVE_ASYNC_INTERRUPT;
		1294
		1295	sub _have_async_interrupt() {
		1296	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1297	&& eval "use Async::Interrupt 1.0 (); 1")
		1298	unless defined $HAVE_ASYNC_INTERRUPT;
		1299
		1300	$HAVE_ASYNC_INTERRUPT
		1301	}
		1302
		1303	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1304	our (%SIG_ASY, %SIG_ASY_W);
		1305	our ($SIG_COUNT, $SIG_TW);
		1306
		1307	sub _signal_exec {
		1308	$HAVE_ASYNC_INTERRUPT
		1309	? $SIGPIPE_R->drain
		1310	: sysread $SIGPIPE_R, my $dummy, 9;
		1311
		1312	while (%SIG_EV) {
		1313	for (keys %SIG_EV) {
		1314	delete $SIG_EV{$_};
		1315	$_->() for values %{ $SIG_CB{$_} || {} };
		1316	}
		1317	}
		1318	}
		1319
		1320	# install a dummy wakeup watcher to reduce signal catching latency
		1321	sub _sig_add() {
		1322	unless ($SIG_COUNT++) {
		1323	# try to align timer on a full-second boundary, if possible
		1324	my $NOW = AnyEvent->now;
		1325
		1326	$SIG_TW = AnyEvent->timer (
		1327	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1328	interval => $MAX_SIGNAL_LATENCY,
		1329	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1330	);
		1331	}
		1332	}
		1333
		1334	sub _sig_del {
		1335	undef $SIG_TW
		1336	unless --$SIG_COUNT;
		1337	}
		1338
		1339	our $_sig_name_init; $_sig_name_init = sub {
		1340	eval q{ # poor man's autoloading
		1341	undef $_sig_name_init;
		1342
		1343	if (_have_async_interrupt) {
		1344	*sig2num = \&Async::Interrupt::sig2num;
		1345	*sig2name = \&Async::Interrupt::sig2name;
		1346	} else {
		1347	require Config;
		1348
		1349	my %signame2num;
		1350	@signame2num{ split ' ', $Config::Config{sig_name} }
		1351	= split ' ', $Config::Config{sig_num};
		1352
		1353	my @signum2name;
		1354	@signum2name[values %signame2num] = keys %signame2num;
		1355
		1356	*sig2num = sub($) {
		1357	$_[0] > 0 ? shift : $signame2num{+shift}
		1358	};
		1359	*sig2name = sub ($) {
		1360	$_[0] > 0 ? $signum2name[+shift] : shift
		1361	};
		1362	}
		1363	};
		1364	die if $@;
		1365	};
		1366
		1367	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1368	sub sig2name($) { &$_sig_name_init; &sig2name }
887		1369
888	sub signal {	1370	sub signal {
		1371	eval q{ # poor man's autoloading {}
		1372	# probe for availability of Async::Interrupt
		1373	if (_have_async_interrupt) {
		1374	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1375
		1376	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1377	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1378
		1379	} else {
		1380	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1381
		1382	require Fcntl;
		1383
		1384	if (AnyEvent::WIN32) {
		1385	require AnyEvent::Util;
		1386
		1387	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1388	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1389	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1390	} else {
		1391	pipe $SIGPIPE_R, $SIGPIPE_W;
		1392	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1393	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1394
		1395	# not strictly required, as $^F is normally 2, but let's make sure...
		1396	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1397	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1398	}
		1399
		1400	$SIGPIPE_R
		1401	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1402
		1403	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1404	}
		1405
		1406	*signal = sub {
889	my (undef, %arg) = @_;	1407	my (undef, %arg) = @_;
890		1408
891	my $signal = uc $arg{signal}	1409	my $signal = uc $arg{signal}
892	or Carp::croak "required option 'signal' is missing";	1410	or Carp::croak "required option 'signal' is missing";
893		1411
		1412	if ($HAVE_ASYNC_INTERRUPT) {
		1413	# async::interrupt
		1414
		1415	$signal = sig2num $signal;
894	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1416	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1417
		1418	$SIG_ASY{$signal} ||= new Async::Interrupt
		1419	cb => sub { undef $SIG_EV{$signal} },
		1420	signal => $signal,
		1421	pipe => [$SIGPIPE_R->filenos],
		1422	pipe_autodrain => 0,
		1423	;
		1424
		1425	} else {
		1426	# pure perl
		1427
		1428	# AE::Util has been loaded in signal
		1429	$signal = sig2name $signal;
		1430	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1431
895	$SIG{$signal} ||= sub {	1432	$SIG{$signal} ||= sub {
896	$_->() for values %{ $SIG_CB{$signal} || {} };	1433	local $!;
		1434	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1435	undef $SIG_EV{$signal};
		1436	};
		1437
		1438	# can't do signal processing without introducing races in pure perl,
		1439	# so limit the signal latency.
		1440	_sig_add;
		1441	}
		1442
		1443	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1444	};
		1445
		1446	*AnyEvent::Base::signal::DESTROY = sub {
		1447	my ($signal, $cb) = @{$_[0]};
		1448
		1449	_sig_del;
		1450
		1451	delete $SIG_CB{$signal}{$cb};
		1452
		1453	$HAVE_ASYNC_INTERRUPT
		1454	? delete $SIG_ASY{$signal}
		1455	: # delete doesn't work with older perls - they then
		1456	# print weird messages, or just unconditionally exit
		1457	# instead of getting the default action.
		1458	undef $SIG{$signal}
		1459	unless keys %{ $SIG_CB{$signal} };
		1460	};
897	};	1461	};
898		1462	die if $@;
899	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1463	&signal
900	}
901
902	sub AnyEvent::Base::Signal::DESTROY {
903	my ($signal, $cb) = @{$_[0]};
904
905	delete $SIG_CB{$signal}{$cb};
906
907	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
908	}	1464	}
909		1465
910	# default implementation for ->child	1466	# default implementation for ->child
911		1467
912	our %PID_CB;	1468	our %PID_CB;
913	our $CHLD_W;	1469	our $CHLD_W;
914	our $CHLD_DELAY_W;	1470	our $CHLD_DELAY_W;
915	our $PID_IDLE;
916	our $WNOHANG;	1471	our $WNOHANG;
917		1472
918	sub _child_wait {	1473	sub _emit_childstatus($$) {
919	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1474	my (undef, $rpid, $rstatus) = @_;
		1475
		1476	$_->($rpid, $rstatus)
920	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1477	for values %{ $PID_CB{$rpid} || {} },
921	(values %{ $PID_CB{0} || {} });	1478	values %{ $PID_CB{0} || {} };
922	}
923
924	undef $PID_IDLE;
925	}	1479	}
926		1480
927	sub _sigchld {	1481	sub _sigchld {
928	# make sure we deliver these changes "synchronous" with the event loop.	1482	my $pid;
929	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1483
930	undef $CHLD_DELAY_W;	1484	AnyEvent->_emit_childstatus ($pid, $?)
931	&_child_wait;	1485	while ($pid = waitpid -1, $WNOHANG) > 0;
932	});
933	}	1486	}
934		1487
935	sub child {	1488	sub child {
936	my (undef, %arg) = @_;	1489	my (undef, %arg) = @_;
937		1490
938	defined (my $pid = $arg{pid} + 0)	1491	defined (my $pid = $arg{pid} + 0)
939	or Carp::croak "required option 'pid' is missing";	1492	or Carp::croak "required option 'pid' is missing";
940		1493
941	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1494	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
942		1495
943	unless ($WNOHANG) {	1496	# WNOHANG is almost cetrainly 1 everywhere
		1497	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1498	? 1
944	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1499	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
945	}
946		1500
947	unless ($CHLD_W) {	1501	unless ($CHLD_W) {
948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1502	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
949	# child could be a zombie already, so make at least one round	1503	# child could be a zombie already, so make at least one round
950	&_sigchld;	1504	&_sigchld;
951	}	1505	}
952		1506
953	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1507	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
954	}	1508	}
955		1509
956	sub AnyEvent::Base::Child::DESTROY {	1510	sub AnyEvent::Base::child::DESTROY {
957	my ($pid, $cb) = @{$_[0]};	1511	my ($pid, $cb) = @{$_[0]};
958		1512
959	delete $PID_CB{$pid}{$cb};	1513	delete $PID_CB{$pid}{$cb};
960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1514	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
961		1515
962	undef $CHLD_W unless keys %PID_CB;	1516	undef $CHLD_W unless keys %PID_CB;
963	}	1517	}
964		1518
		1519	# idle emulation is done by simply using a timer, regardless
		1520	# of whether the process is idle or not, and not letting
		1521	# the callback use more than 50% of the time.
		1522	sub idle {
		1523	my (undef, %arg) = @_;
		1524
		1525	my ($cb, $w, $rcb) = $arg{cb};
		1526
		1527	$rcb = sub {
		1528	if ($cb) {
		1529	$w = _time;
		1530	&$cb;
		1531	$w = _time - $w;
		1532
		1533	# never use more then 50% of the time for the idle watcher,
		1534	# within some limits
		1535	$w = 0.0001 if $w < 0.0001;
		1536	$w = 5 if $w > 5;
		1537
		1538	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1539	} else {
		1540	# clean up...
		1541	undef $w;
		1542	undef $rcb;
		1543	}
		1544	};
		1545
		1546	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1547
		1548	bless \\$cb, "AnyEvent::Base::idle"
		1549	}
		1550
		1551	sub AnyEvent::Base::idle::DESTROY {
		1552	undef $${$_[0]};
		1553	}
		1554
965	package AnyEvent::CondVar;	1555	package AnyEvent::CondVar;
966		1556
967	our @ISA = AnyEvent::CondVar::Base::;	1557	our @ISA = AnyEvent::CondVar::Base::;
968		1558
969	package AnyEvent::CondVar::Base;	1559	package AnyEvent::CondVar::Base;
970		1560
971	use overload	1561	#use overload
972	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1562	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
973	fallback => 1;	1563	# fallback => 1;
		1564
		1565	# save 300+ kilobytes by dirtily hardcoding overloading
		1566	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1567	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1568	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1569	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1570
		1571	our $WAITING;
974		1572
975	sub _send {	1573	sub _send {
976	# nop	1574	# nop
977	}	1575	}
978		1576
…		…
991	sub ready {	1589	sub ready {
992	$_[0]{_ae_sent}	1590	$_[0]{_ae_sent}
993	}	1591	}
994		1592
995	sub _wait {	1593	sub _wait {
		1594	$WAITING
		1595	and !$_[0]{_ae_sent}
		1596	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1597
		1598	local $WAITING = 1;
996	AnyEvent->one_event while !$_[0]{_ae_sent};	1599	AnyEvent->one_event while !$_[0]{_ae_sent};
997	}	1600	}
998		1601
999	sub recv {	1602	sub recv {
1000	$_[0]->_wait;	1603	$_[0]->_wait;
…		…
1019	}	1622	}
1020		1623
1021	# undocumented/compatibility with pre-3.4	1624	# undocumented/compatibility with pre-3.4
1022	*broadcast = \&send;	1625	*broadcast = \&send;
1023	*wait = \&_wait;	1626	*wait = \&_wait;
		1627
		1628	=head1 ERROR AND EXCEPTION HANDLING
		1629
		1630	In general, AnyEvent does not do any error handling - it relies on the
		1631	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1632	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1633	checking of all AnyEvent methods, however, which is highly useful during
		1634	development.
		1635
		1636	As for exception handling (i.e. runtime errors and exceptions thrown while
		1637	executing a callback), this is not only highly event-loop specific, but
		1638	also not in any way wrapped by this module, as this is the job of the main
		1639	program.
		1640
		1641	The pure perl event loop simply re-throws the exception (usually
		1642	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1643	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1644	so on.
		1645
		1646	=head1 ENVIRONMENT VARIABLES
		1647
		1648	The following environment variables are used by this module or its
		1649	submodules.
		1650
		1651	Note that AnyEvent will remove I<all> environment variables starting with
		1652	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1653	enabled.
		1654
		1655	=over 4
		1656
		1657	=item C<PERL_ANYEVENT_VERBOSE>
		1658
		1659	By default, AnyEvent will be completely silent except in fatal
		1660	conditions. You can set this environment variable to make AnyEvent more
		1661	talkative.
		1662
		1663	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1664	conditions, such as not being able to load the event model specified by
		1665	C<PERL_ANYEVENT_MODEL>.
		1666
		1667	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1668	model it chooses.
		1669
		1670	When set to C<8> or higher, then AnyEvent will report extra information on
		1671	which optional modules it loads and how it implements certain features.
		1672
		1673	=item C<PERL_ANYEVENT_STRICT>
		1674
		1675	AnyEvent does not do much argument checking by default, as thorough
		1676	argument checking is very costly. Setting this variable to a true value
		1677	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1678	check the arguments passed to most method calls. If it finds any problems,
		1679	it will croak.
		1680
		1681	In other words, enables "strict" mode.
		1682
		1683	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1684	>>, it is definitely recommended to keep it off in production. Keeping
		1685	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1686	can be very useful, however.
		1687
		1688	=item C<PERL_ANYEVENT_MODEL>
		1689
		1690	This can be used to specify the event model to be used by AnyEvent, before
		1691	auto detection and -probing kicks in. It must be a string consisting
		1692	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1693	and the resulting module name is loaded and if the load was successful,
		1694	used as event model. If it fails to load AnyEvent will proceed with
		1695	auto detection and -probing.
		1696
		1697	This functionality might change in future versions.
		1698
		1699	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1700	could start your program like this:
		1701
		1702	PERL_ANYEVENT_MODEL=Perl perl ...
		1703
		1704	=item C<PERL_ANYEVENT_PROTOCOLS>
		1705
		1706	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1707	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1708	of auto probing).
		1709
		1710	Must be set to a comma-separated list of protocols or address families,
		1711	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1712	used, and preference will be given to protocols mentioned earlier in the
		1713	list.
		1714
		1715	This variable can effectively be used for denial-of-service attacks
		1716	against local programs (e.g. when setuid), although the impact is likely
		1717	small, as the program has to handle conenction and other failures anyways.
		1718
		1719	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1720	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1721	- only support IPv4, never try to resolve or contact IPv6
		1722	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1723	IPv6, but prefer IPv6 over IPv4.
		1724
		1725	=item C<PERL_ANYEVENT_EDNS0>
		1726
		1727	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1728	for DNS. This extension is generally useful to reduce DNS traffic, but
		1729	some (broken) firewalls drop such DNS packets, which is why it is off by
		1730	default.
		1731
		1732	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1733	EDNS0 in its DNS requests.
		1734
		1735	=item C<PERL_ANYEVENT_MAX_FORKS>
		1736
		1737	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1738	will create in parallel.
		1739
		1740	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1741
		1742	The default value for the C<max_outstanding> parameter for the default DNS
		1743	resolver - this is the maximum number of parallel DNS requests that are
		1744	sent to the DNS server.
		1745
		1746	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1747
		1748	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1749	configuration) in the default resolver. When set to the empty string, no
		1750	default config will be used.
		1751
		1752	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1753
		1754	When neither C<ca_file> nor C<ca_path> was specified during
		1755	L<AnyEvent::TLS> context creation, and either of these environment
		1756	variables exist, they will be used to specify CA certificate locations
		1757	instead of a system-dependent default.
		1758
		1759	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1760
		1761	When these are set to C<1>, then the respective modules are not
		1762	loaded. Mostly good for testing AnyEvent itself.
		1763
		1764	=back
1024		1765
1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1766	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1026		1767
1027	This is an advanced topic that you do not normally need to use AnyEvent in	1768	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	1769	a module. This section is only of use to event loop authors who want to
…		…
1062		1803
1063	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1804	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1064	condition variables: code blocking while waiting for a condition will	1805	condition variables: code blocking while waiting for a condition will
1065	C<die>. This still works with most modules/usages, and blocking calls must	1806	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.	1807	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		1808
1141	=head1 EXAMPLE PROGRAM	1809	=head1 EXAMPLE PROGRAM
1142		1810
1143	The following program uses an I/O watcher to read data from STDIN, a timer	1811	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	1812	to display a message once per second, and a condition variable to quit the
…		…
1338	watcher.	2006	watcher.
1339		2007
1340	=head3 Results	2008	=head3 Results
1341		2009
1342	name watchers bytes create invoke destroy comment	2010	name watchers bytes create invoke destroy comment
1343	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2011	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	2012	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	2013	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	2014	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	2015	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	2016	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2017	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2018	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	2019	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	2020	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	2021	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	2022	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1353		2023
1354	=head3 Discussion	2024	=head3 Discussion
1355		2025
1356	The benchmark does I<not> measure scalability of the event loop very	2026	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)	2027	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	2052	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.	2053	them active), of course, but this was not subject of this benchmark.
1384		2054
1385	The C<Event> module has a relatively high setup and callback invocation	2055	The C<Event> module has a relatively high setup and callback invocation
1386	cost, but overall scores in on the third place.	2056	cost, but overall scores in on the third place.
		2057
		2058	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2059	when using its pure perl backend.
1387		2060
1388	C<Glib>'s memory usage is quite a bit higher, but it features a	2061	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	2062	faster callback invocation and overall ends up in the same class as
1390	C<Event>. However, Glib scales extremely badly, doubling the number of	2063	C<Event>. However, Glib scales extremely badly, doubling the number of
1391	watchers increases the processing time by more than a factor of four,	2064	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	2142	it to another server. This includes deleting the old timeout and creating
1470	a new one that moves the timeout into the future.	2143	a new one that moves the timeout into the future.
1471		2144
1472	=head3 Results	2145	=head3 Results
1473		2146
1474	name sockets create request	2147	name sockets create request
1475	EV 20000 69.01 11.16	2148	EV 20000 69.01 11.16
1476	Perl 20000 73.32 35.87	2149	Perl 20000 73.32 35.87
		2150	IOAsync 20000 157.00 98.14 epoll
		2151	IOAsync 20000 159.31 616.06 poll
1477	Event 20000 212.62 257.32	2152	Event 20000 212.62 257.32
1478	Glib 20000 651.16 1896.30	2153	Glib 20000 651.16 1896.30
1479	POE 20000 349.67 12317.24 uses POE::Loop::Event	2154	POE 20000 349.67 12317.24 uses POE::Loop::Event
1480		2155
1481	=head3 Discussion	2156	=head3 Discussion
1482		2157
1483	This benchmark I<does> measure scalability and overall performance of the	2158	This benchmark I<does> measure scalability and overall performance of the
1484	particular event loop.	2159	particular event loop.
…		…
1486	EV is again fastest. Since it is using epoll on my system, the setup time	2161	EV is again fastest. Since it is using epoll on my system, the setup time
1487	is relatively high, though.	2162	is relatively high, though.
1488		2163
1489	Perl surprisingly comes second. It is much faster than the C-based event	2164	Perl surprisingly comes second. It is much faster than the C-based event
1490	loops Event and Glib.	2165	loops Event and Glib.
		2166
		2167	IO::Async performs very well when using its epoll backend, and still quite
		2168	good compared to Glib when using its pure perl backend.
1491		2169
1492	Event suffers from high setup time as well (look at its code and you will	2170	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	2171	understand why). Callback invocation also has a high overhead compared to
1494	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2172	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1495	uses select or poll in basically all documented configurations.	2173	uses select or poll in basically all documented configurations.
…		…
1558	=item * C-based event loops perform very well with small number of	2236	=item * C-based event loops perform very well with small number of
1559	watchers, as the management overhead dominates.	2237	watchers, as the management overhead dominates.
1560		2238
1561	=back	2239	=back
1562		2240
		2241	=head2 THE IO::Lambda BENCHMARK
		2242
		2243	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2244	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2245	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2246	shouldn't come as a surprise to anybody). As such, the benchmark is
		2247	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2248	very optimal. But how would AnyEvent compare when used without the extra
		2249	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2250
		2251	The benchmark itself creates an echo-server, and then, for 500 times,
		2252	connects to the echo server, sends a line, waits for the reply, and then
		2253	creates the next connection. This is a rather bad benchmark, as it doesn't
		2254	test the efficiency of the framework or much non-blocking I/O, but it is a
		2255	benchmark nevertheless.
		2256
		2257	name runtime
		2258	Lambda/select 0.330 sec
		2259	+ optimized 0.122 sec
		2260	Lambda/AnyEvent 0.327 sec
		2261	+ optimized 0.138 sec
		2262	Raw sockets/select 0.077 sec
		2263	POE/select, components 0.662 sec
		2264	POE/select, raw sockets 0.226 sec
		2265	POE/select, optimized 0.404 sec
		2266
		2267	AnyEvent/select/nb 0.085 sec
		2268	AnyEvent/EV/nb 0.068 sec
		2269	+state machine 0.134 sec
		2270
		2271	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2272	benchmarks actually make blocking connects and use 100% blocking I/O,
		2273	defeating the purpose of an event-based solution. All of the newly
		2274	written AnyEvent benchmarks use 100% non-blocking connects (using
		2275	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2276	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2277	generally require a lot more bookkeeping and event handling than blocking
		2278	connects (which involve a single syscall only).
		2279
		2280	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2281	offers similar expressive power as POE and IO::Lambda, using conventional
		2282	Perl syntax. This means that both the echo server and the client are 100%
		2283	non-blocking, further placing it at a disadvantage.
		2284
		2285	As you can see, the AnyEvent + EV combination even beats the
		2286	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2287	backend easily beats IO::Lambda and POE.
		2288
		2289	And even the 100% non-blocking version written using the high-level (and
		2290	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2291	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2292	in a non-blocking way.
		2293
		2294	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2295	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2296	part of the IO::lambda distribution and were used without any changes.
		2297
		2298
		2299	=head1 SIGNALS
		2300
		2301	AnyEvent currently installs handlers for these signals:
		2302
		2303	=over 4
		2304
		2305	=item SIGCHLD
		2306
		2307	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2308	emulation for event loops that do not support them natively. Also, some
		2309	event loops install a similar handler.
		2310
		2311	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2312	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2313
		2314	=item SIGPIPE
		2315
		2316	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2317	when AnyEvent gets loaded.
		2318
		2319	The rationale for this is that AnyEvent users usually do not really depend
		2320	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2321	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2322	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2323	some random socket.
		2324
		2325	The rationale for installing a no-op handler as opposed to ignoring it is
		2326	that this way, the handler will be restored to defaults on exec.
		2327
		2328	Feel free to install your own handler, or reset it to defaults.
		2329
		2330	=back
		2331
		2332	=cut
		2333
		2334	undef $SIG{CHLD}
		2335	if $SIG{CHLD} eq 'IGNORE';
		2336
		2337	$SIG{PIPE} = sub { }
		2338	unless defined $SIG{PIPE};
		2339
		2340	=head1 RECOMMENDED/OPTIONAL MODULES
		2341
		2342	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2343	it's built-in modules) are required to use it.
		2344
		2345	That does not mean that AnyEvent won't take advantage of some additional
		2346	modules if they are installed.
		2347
		2348	This section epxlains which additional modules will be used, and how they
		2349	affect AnyEvent's operetion.
		2350
		2351	=over 4
		2352
		2353	=item L<Async::Interrupt>
		2354
		2355	This slightly arcane module is used to implement fast signal handling: To
		2356	my knowledge, there is no way to do completely race-free and quick
		2357	signal handling in pure perl. To ensure that signals still get
		2358	delivered, AnyEvent will start an interval timer to wake up perl (and
		2359	catch the signals) with some delay (default is 10 seconds, look for
		2360	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2361
		2362	If this module is available, then it will be used to implement signal
		2363	catching, which means that signals will not be delayed, and the event loop
		2364	will not be interrupted regularly, which is more efficient (And good for
		2365	battery life on laptops).
		2366
		2367	This affects not just the pure-perl event loop, but also other event loops
		2368	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2369
		2370	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2371	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2372	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2373	does nothing for those backends.
		2374
		2375	=item L<EV>
		2376
		2377	This module isn't really "optional", as it is simply one of the backend
		2378	event loops that AnyEvent can use. However, it is simply the best event
		2379	loop available in terms of features, speed and stability: It supports
		2380	the AnyEvent API optimally, implements all the watcher types in XS, does
		2381	automatic timer adjustments even when no monotonic clock is available,
		2382	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2383	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2384	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2385
		2386	=item L<Guard>
		2387
		2388	The guard module, when used, will be used to implement
		2389	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2390	lot less memory), but otherwise doesn't affect guard operation much. It is
		2391	purely used for performance.
		2392
		2393	=item L<JSON> and L<JSON::XS>
		2394
		2395	This module is required when you want to read or write JSON data via
		2396	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2397	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2398
		2399	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2400	installed.
		2401
		2402	=item L<Net::SSLeay>
		2403
		2404	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2405	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2406	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2407
		2408	=item L<Time::HiRes>
		2409
		2410	This module is part of perl since release 5.008. It will be used when the
		2411	chosen event library does not come with a timing source on it's own. The
		2412	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2413	try to use a monotonic clock for timing stability.
		2414
		2415	=back
		2416
1563		2417
1564	=head1 FORK	2418	=head1 FORK
1565		2419
1566	Most event libraries are not fork-safe. The ones who are usually are	2420	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>	2421	because they rely on inefficient but fork-safe C<select> or C<poll>
1568	calls. Only L<EV> is fully fork-aware.	2422	calls. Only L<EV> is fully fork-aware.
1569		2423
1570	If you have to fork, you must either do so I<before> creating your first	2424	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.	2425	watcher OR you must not use AnyEvent at all in the child OR you must do
		2426	something completely out of the scope of AnyEvent.
1572		2427
1573		2428
1574	=head1 SECURITY CONSIDERATIONS	2429	=head1 SECURITY CONSIDERATIONS
1575		2430
1576	AnyEvent can be forced to load any event model via	2431	AnyEvent can be forced to load any event model via
…		…
1581	specified in the variable.	2436	specified in the variable.
1582		2437
1583	You can make AnyEvent completely ignore this variable by deleting it	2438	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:	2439	before the first watcher gets created, e.g. with a C<BEGIN> block:
1585		2440
1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2441	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1587		2442
1588	use AnyEvent;	2443	use AnyEvent;
1589		2444
1590	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2445	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	2446	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).	2447	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2448	$ENV{PERL_ANYEVENT_STRICT}.
		2449
		2450	Note that AnyEvent will remove I<all> environment variables starting with
		2451	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2452	enabled.
		2453
		2454
		2455	=head1 BUGS
		2456
		2457	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2458	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2459	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2460	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2461	pronounced).
1593		2462
1594		2463
1595	=head1 SEE ALSO	2464	=head1 SEE ALSO
1596		2465
1597	Utility functions: L<AnyEvent::Util>.	2466	Utility functions: L<AnyEvent::Util>.
…		…
1600	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2469	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1601		2470
1602	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2471	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1603	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2472	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1604	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2473	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1605	L<AnyEvent::Impl::POE>.	2474	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1606		2475
1607	Non-blocking file handles, sockets, TCP clients and	2476	Non-blocking file handles, sockets, TCP clients and
1608	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2477	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1609		2478
1610	Asynchronous DNS: L<AnyEvent::DNS>.	2479	Asynchronous DNS: L<AnyEvent::DNS>.
1611		2480
1612	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2481	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2482	L<Coro::Event>,
1613		2483
1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2484	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2485	L<AnyEvent::HTTP>.
1615		2486
1616		2487
1617	=head1 AUTHOR	2488	=head1 AUTHOR
1618		2489
1619	Marc Lehmann <schmorp@schmorp.de>	2490	Marc Lehmann <schmorp@schmorp.de>
1620	http://home.schmorp.de/	2491	http://home.schmorp.de/
1621		2492
1622	=cut	2493	=cut
1623		2494
1624	1	2495	1
1625		2496

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines