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Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC vs.
Revision 1.228 by root, Wed Jul 8 01:11:12 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor, see below) to
		182	watch for events (AnyEvent might or might not keep a reference to this
		183	file handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
171		213
		214	=head3 GETTING A FILE HANDLE FROM A FILE DESCRIPTOR
		215
		216	It is not uncommon to only have a file descriptor, while AnyEvent requires
		217	a Perl file handle.
		218
		219	There are basically two methods to convert a file descriptor into a file handle. If you own
		220	the file descriptor, you can open it with C<&=>, as in:
		221
		222	open my $fh, "<&=$fileno" or die "xxx: §!";
		223
		224	This will "own" the file descriptor, meaning that when C<$fh> is
		225	destroyed, it will automatically close the C<$fileno>. Also, note that
		226	the open mode (read, write, read/write) must correspond with how the
		227	underlying file descriptor was opened.
		228
		229	In many cases, taking over the file descriptor is now what you want, in
		230	which case the only alternative is to dup the file descriptor:
		231
		232	open my $fh, "<&$fileno" or die "xxx: $!";
		233
		234	This has the advantage of not closing the file descriptor and the
		235	disadvantage of making a slow copy.
		236
172	=head2 TIME WATCHERS	237	=head2 TIME WATCHERS
173		238
174	You can create a time watcher by calling the C<< AnyEvent->timer >>	239	You can create a time watcher by calling the C<< AnyEvent->timer >>
175	method with the following mandatory arguments:	240	method with the following mandatory arguments:
176		241
…		…
180		245
181	Although the callback might get passed parameters, their value and	246	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	247	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	248	callbacks cannot use arguments passed to time watcher callbacks.
184		249
185	The timer callback will be invoked at most once: if you want a repeating	250	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	251	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	252	callback will be invoked regularly at that interval (in fractional
		253	seconds) after the first invocation. If C<interval> is specified with a
		254	false value, then it is treated as if it were missing.
188		255
189	Example:	256	The callback will be rescheduled before invoking the callback, but no
		257	attempt is done to avoid timer drift in most backends, so the interval is
		258	only approximate.
190		259
191	# fire an event after 7.7 seconds	260	Example: fire an event after 7.7 seconds.
		261
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	262	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	263	warn "timeout\n";
194	});	264	});
195		265
196	# to cancel the timer:	266	# to cancel the timer:
197	undef $w;	267	undef $w;
198		268
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	269	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		270
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	271	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		272	warn "timeout\n";
207	};	273	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		274
212	=head3 TIMING ISSUES	275	=head3 TIMING ISSUES
213		276
214	There are two ways to handle timers: based on real time (relative, "fire	277	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	278	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	290	timers.
228		291
229	AnyEvent always prefers relative timers, if available, matching the	292	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	293	AnyEvent API.
231		294
		295	AnyEvent has two additional methods that return the "current time":
		296
		297	=over 4
		298
		299	=item AnyEvent->time
		300
		301	This returns the "current wallclock time" as a fractional number of
		302	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		303	return, and the result is guaranteed to be compatible with those).
		304
		305	It progresses independently of any event loop processing, i.e. each call
		306	will check the system clock, which usually gets updated frequently.
		307
		308	=item AnyEvent->now
		309
		310	This also returns the "current wallclock time", but unlike C<time>, above,
		311	this value might change only once per event loop iteration, depending on
		312	the event loop (most return the same time as C<time>, above). This is the
		313	time that AnyEvent's timers get scheduled against.
		314
		315	I<In almost all cases (in all cases if you don't care), this is the
		316	function to call when you want to know the current time.>
		317
		318	This function is also often faster then C<< AnyEvent->time >>, and
		319	thus the preferred method if you want some timestamp (for example,
		320	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		321
		322	The rest of this section is only of relevance if you try to be very exact
		323	with your timing, you can skip it without bad conscience.
		324
		325	For a practical example of when these times differ, consider L<Event::Lib>
		326	and L<EV> and the following set-up:
		327
		328	The event loop is running and has just invoked one of your callback at
		329	time=500 (assume no other callbacks delay processing). In your callback,
		330	you wait a second by executing C<sleep 1> (blocking the process for a
		331	second) and then (at time=501) you create a relative timer that fires
		332	after three seconds.
		333
		334	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		335	both return C<501>, because that is the current time, and the timer will
		336	be scheduled to fire at time=504 (C<501> + C<3>).
		337
		338	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		339	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		340	last event processing phase started. With L<EV>, your timer gets scheduled
		341	to run at time=503 (C<500> + C<3>).
		342
		343	In one sense, L<Event::Lib> is more exact, as it uses the current time
		344	regardless of any delays introduced by event processing. However, most
		345	callbacks do not expect large delays in processing, so this causes a
		346	higher drift (and a lot more system calls to get the current time).
		347
		348	In another sense, L<EV> is more exact, as your timer will be scheduled at
		349	the same time, regardless of how long event processing actually took.
		350
		351	In either case, if you care (and in most cases, you don't), then you
		352	can get whatever behaviour you want with any event loop, by taking the
		353	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		354	account.
		355
		356	=item AnyEvent->now_update
		357
		358	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		359	the current time for each loop iteration (see the discussion of L<<
		360	AnyEvent->now >>, above).
		361
		362	When a callback runs for a long time (or when the process sleeps), then
		363	this "current" time will differ substantially from the real time, which
		364	might affect timers and time-outs.
		365
		366	When this is the case, you can call this method, which will update the
		367	event loop's idea of "current time".
		368
		369	Note that updating the time I<might> cause some events to be handled.
		370
		371	=back
		372
232	=head2 SIGNAL WATCHERS	373	=head2 SIGNAL WATCHERS
233		374
234	You can watch for signals using a signal watcher, C<signal> is the signal	375	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	376	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	377	callback to be invoked whenever a signal occurs.
237		378
238	Although the callback might get passed parameters, their value and	379	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	380	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	381	callbacks cannot use arguments passed to signal watcher callbacks.
241		382
…		…
257	=head2 CHILD PROCESS WATCHERS	398	=head2 CHILD PROCESS WATCHERS
258		399
259	You can also watch on a child process exit and catch its exit status.	400	You can also watch on a child process exit and catch its exit status.
260		401
261	The child process is specified by the C<pid> argument (if set to C<0>, it	402	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	403	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	404	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	405	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	406
266	you I<can> rely on child watcher callback arguments.	407	The callback will be called with the pid and exit status (as returned by
		408	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		409	callback arguments.
		410
		411	This watcher type works by installing a signal handler for C<SIGCHLD>,
		412	and since it cannot be shared, nothing else should use SIGCHLD or reap
		413	random child processes (waiting for specific child processes, e.g. inside
		414	C<system>, is just fine).
267		415
268	There is a slight catch to child watchers, however: you usually start them	416	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	417	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	418	have exited already (and no SIGCHLD will be sent anymore).
271		419
272	Not all event models handle this correctly (POE doesn't), but even for	420	Not all event models handle this correctly (neither POE nor IO::Async do,
		421	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	422	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	423	the process exits (i.e. before you fork in the first place). AnyEvent's
		424	pure perl event loop handles all cases correctly regardless of when you
		425	start the watcher.
275		426
276	This means you cannot create a child watcher as the very first thing in an	427	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	428	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	429	watcher before you C<fork> the child (alternatively, you can call
		430	C<AnyEvent::detect>).
279		431
280	Example: fork a process and wait for it	432	Example: fork a process and wait for it
281		433
282	my $done = AnyEvent->condvar;	434	my $done = AnyEvent->condvar;
283		435
284	my $pid = fork or exit 5;	436	my $pid = fork or exit 5;
285		437
286	my $w = AnyEvent->child (	438	my $w = AnyEvent->child (
287	pid => $pid,	439	pid => $pid,
288	cb => sub {	440	cb => sub {
289	my ($pid, $status) = @_;	441	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	442	warn "pid $pid exited with status $status";
291	$done->send;	443	$done->send;
292	},	444	},
293	);	445	);
294		446
295	# do something else, then wait for process exit	447	# do something else, then wait for process exit
296	$done->recv;	448	$done->recv;
		449
		450	=head2 IDLE WATCHERS
		451
		452	Sometimes there is a need to do something, but it is not so important
		453	to do it instantly, but only when there is nothing better to do. This
		454	"nothing better to do" is usually defined to be "no other events need
		455	attention by the event loop".
		456
		457	Idle watchers ideally get invoked when the event loop has nothing
		458	better to do, just before it would block the process to wait for new
		459	events. Instead of blocking, the idle watcher is invoked.
		460
		461	Most event loops unfortunately do not really support idle watchers (only
		462	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		463	will simply call the callback "from time to time".
		464
		465	Example: read lines from STDIN, but only process them when the
		466	program is otherwise idle:
		467
		468	my @lines; # read data
		469	my $idle_w;
		470	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		471	push @lines, scalar <STDIN>;
		472
		473	# start an idle watcher, if not already done
		474	$idle_w ||= AnyEvent->idle (cb => sub {
		475	# handle only one line, when there are lines left
		476	if (my $line = shift @lines) {
		477	print "handled when idle: $line";
		478	} else {
		479	# otherwise disable the idle watcher again
		480	undef $idle_w;
		481	}
		482	});
		483	});
297		484
298	=head2 CONDITION VARIABLES	485	=head2 CONDITION VARIABLES
299		486
300	If you are familiar with some event loops you will know that all of them	487	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	488	require you to run some blocking "loop", "run" or similar function that
…		…
307	The instrument to do that is called a "condition variable", so called	494	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	495	because they represent a condition that must become true.
309		496
310	Condition variables can be created by calling the C<< AnyEvent->condvar	497	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	498	>> method, usually without arguments. The only argument pair allowed is
		499
312	C<cb>, which specifies a callback to be called when the condition variable	500	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	501	becomes true, with the condition variable as the first argument (but not
		502	the results).
314		503
315	After creation, the condition variable is "false" until it becomes "true"	504	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	505	by calling the C<send> method (or calling the condition variable as if it
317	were a callback, read about the caveats in the description for the C<<	506	were a callback, read about the caveats in the description for the C<<
318	->send >> method).	507	->send >> method).
…		…
374		563
375	my $done = AnyEvent->condvar;	564	my $done = AnyEvent->condvar;
376	my $delay = AnyEvent->timer (after => 5, cb => $done);	565	my $delay = AnyEvent->timer (after => 5, cb => $done);
377	$done->recv;	566	$done->recv;
378		567
		568	Example: Imagine an API that returns a condvar and doesn't support
		569	callbacks. This is how you make a synchronous call, for example from
		570	the main program:
		571
		572	use AnyEvent::CouchDB;
		573
		574	...
		575
		576	my @info = $couchdb->info->recv;
		577
		578	And this is how you would just ste a callback to be called whenever the
		579	results are available:
		580
		581	$couchdb->info->cb (sub {
		582	my @info = $_[0]->recv;
		583	});
		584
379	=head3 METHODS FOR PRODUCERS	585	=head3 METHODS FOR PRODUCERS
380		586
381	These methods should only be used by the producing side, i.e. the	587	These methods should only be used by the producing side, i.e. the
382	code/module that eventually sends the signal. Note that it is also	588	code/module that eventually sends the signal. Note that it is also
383	the producer side which creates the condvar in most cases, but it isn't	589	the producer side which creates the condvar in most cases, but it isn't
…		…
416		622
417	=item $cv->begin ([group callback])	623	=item $cv->begin ([group callback])
418		624
419	=item $cv->end	625	=item $cv->end
420		626
421	These two methods are EXPERIMENTAL and MIGHT CHANGE.
422
423	These two methods can be used to combine many transactions/events into	627	These two methods can be used to combine many transactions/events into
424	one. For example, a function that pings many hosts in parallel might want	628	one. For example, a function that pings many hosts in parallel might want
425	to use a condition variable for the whole process.	629	to use a condition variable for the whole process.
426		630
427	Every call to C<< ->begin >> will increment a counter, and every call to	631	Every call to C<< ->begin >> will increment a counter, and every call to
428	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	632	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
429	>>, the (last) callback passed to C<begin> will be executed. That callback	633	>>, the (last) callback passed to C<begin> will be executed. That callback
430	is I<supposed> to call C<< ->send >>, but that is not required. If no	634	is I<supposed> to call C<< ->send >>, but that is not required. If no
431	callback was set, C<send> will be called without any arguments.	635	callback was set, C<send> will be called without any arguments.
432		636
433	Let's clarify this with the ping example:	637	You can think of C<< $cv->send >> giving you an OR condition (one call
		638	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		639	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		640
		641	Let's start with a simple example: you have two I/O watchers (for example,
		642	STDOUT and STDERR for a program), and you want to wait for both streams to
		643	close before activating a condvar:
		644
		645	my $cv = AnyEvent->condvar;
		646
		647	$cv->begin; # first watcher
		648	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		649	defined sysread $fh1, my $buf, 4096
		650	or $cv->end;
		651	});
		652
		653	$cv->begin; # second watcher
		654	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		655	defined sysread $fh2, my $buf, 4096
		656	or $cv->end;
		657	});
		658
		659	$cv->recv;
		660
		661	This works because for every event source (EOF on file handle), there is
		662	one call to C<begin>, so the condvar waits for all calls to C<end> before
		663	sending.
		664
		665	The ping example mentioned above is slightly more complicated, as the
		666	there are results to be passwd back, and the number of tasks that are
		667	begung can potentially be zero:
434		668
435	my $cv = AnyEvent->condvar;	669	my $cv = AnyEvent->condvar;
436		670
437	my %result;	671	my %result;
438	$cv->begin (sub { $cv->send (\%result) });	672	$cv->begin (sub { $cv->send (\%result) });
…		…
458	loop, which serves two important purposes: first, it sets the callback	692	loop, which serves two important purposes: first, it sets the callback
459	to be called once the counter reaches C<0>, and second, it ensures that	693	to be called once the counter reaches C<0>, and second, it ensures that
460	C<send> is called even when C<no> hosts are being pinged (the loop	694	C<send> is called even when C<no> hosts are being pinged (the loop
461	doesn't execute once).	695	doesn't execute once).
462		696
463	This is the general pattern when you "fan out" into multiple subrequests:	697	This is the general pattern when you "fan out" into multiple (but
464	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	698	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
465	is called at least once, and then, for each subrequest you start, call	699	the callback and ensure C<end> is called at least once, and then, for each
466	C<begin> and for each subrequest you finish, call C<end>.	700	subrequest you start, call C<begin> and for each subrequest you finish,
		701	call C<end>.
467		702
468	=back	703	=back
469		704
470	=head3 METHODS FOR CONSUMERS	705	=head3 METHODS FOR CONSUMERS
471		706
…		…
516	=item $bool = $cv->ready	751	=item $bool = $cv->ready
517		752
518	Returns true when the condition is "true", i.e. whether C<send> or	753	Returns true when the condition is "true", i.e. whether C<send> or
519	C<croak> have been called.	754	C<croak> have been called.
520		755
521	=item $cb = $cv->cb ([new callback])	756	=item $cb = $cv->cb ($cb->($cv))
522		757
523	This is a mutator function that returns the callback set and optionally	758	This is a mutator function that returns the callback set and optionally
524	replaces it before doing so.	759	replaces it before doing so.
525		760
526	The callback will be called when the condition becomes "true", i.e. when	761	The callback will be called when the condition becomes "true", i.e. when
527	C<send> or C<croak> are called. Calling C<recv> inside the callback	762	C<send> or C<croak> are called, with the only argument being the condition
528	or at any later time is guaranteed not to block.	763	variable itself. Calling C<recv> inside the callback or at any later time
		764	is guaranteed not to block.
529		765
530	=back	766	=back
531		767
532	=head1 GLOBAL VARIABLES AND FUNCTIONS	768	=head1 GLOBAL VARIABLES AND FUNCTIONS
533		769
…		…
550	AnyEvent::Impl::Tk based on Tk, very bad choice.	786	AnyEvent::Impl::Tk based on Tk, very bad choice.
551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	787	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	788	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
553	AnyEvent::Impl::POE based on POE, not generic enough for full support.	789	AnyEvent::Impl::POE based on POE, not generic enough for full support.
554		790
		791	# warning, support for IO::Async is only partial, as it is too broken
		792	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		793	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		794
555	There is no support for WxWidgets, as WxWidgets has no support for	795	There is no support for WxWidgets, as WxWidgets has no support for
556	watching file handles. However, you can use WxWidgets through the	796	watching file handles. However, you can use WxWidgets through the
557	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	797	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
558	second, which was considered to be too horrible to even consider for	798	second, which was considered to be too horrible to even consider for
559	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	799	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
662	=item L<AnyEvent::Util>	902	=item L<AnyEvent::Util>
663		903
664	Contains various utility functions that replace often-used but blocking	904	Contains various utility functions that replace often-used but blocking
665	functions such as C<inet_aton> by event-/callback-based versions.	905	functions such as C<inet_aton> by event-/callback-based versions.
666		906
667	=item L<AnyEvent::Handle>
668
669	Provide read and write buffers and manages watchers for reads and writes.
670
671	=item L<AnyEvent::Socket>	907	=item L<AnyEvent::Socket>
672		908
673	Provides various utility functions for (internet protocol) sockets,	909	Provides various utility functions for (internet protocol) sockets,
674	addresses and name resolution. Also functions to create non-blocking tcp	910	addresses and name resolution. Also functions to create non-blocking tcp
675	connections or tcp servers, with IPv6 and SRV record support and more.	911	connections or tcp servers, with IPv6 and SRV record support and more.
676		912
		913	=item L<AnyEvent::Handle>
		914
		915	Provide read and write buffers, manages watchers for reads and writes,
		916	supports raw and formatted I/O, I/O queued and fully transparent and
		917	non-blocking SSL/TLS.
		918
677	=item L<AnyEvent::DNS>	919	=item L<AnyEvent::DNS>
678		920
679	Provides rich asynchronous DNS resolver capabilities.	921	Provides rich asynchronous DNS resolver capabilities.
680		922
		923	=item L<AnyEvent::HTTP>
		924
		925	A simple-to-use HTTP library that is capable of making a lot of concurrent
		926	HTTP requests.
		927
681	=item L<AnyEvent::HTTPD>	928	=item L<AnyEvent::HTTPD>
682		929
683	Provides a simple web application server framework.	930	Provides a simple web application server framework.
684		931
685	=item L<AnyEvent::FastPing>	932	=item L<AnyEvent::FastPing>
686		933
687	The fastest ping in the west.	934	The fastest ping in the west.
688		935
		936	=item L<AnyEvent::DBI>
		937
		938	Executes L<DBI> requests asynchronously in a proxy process.
		939
		940	=item L<AnyEvent::AIO>
		941
		942	Truly asynchronous I/O, should be in the toolbox of every event
		943	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		944	together.
		945
		946	=item L<AnyEvent::BDB>
		947
		948	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		949	L<BDB> and AnyEvent together.
		950
		951	=item L<AnyEvent::GPSD>
		952
		953	A non-blocking interface to gpsd, a daemon delivering GPS information.
		954
		955	=item L<AnyEvent::IGS>
		956
		957	A non-blocking interface to the Internet Go Server protocol (used by
		958	L<App::IGS>).
		959
689	=item L<Net::IRC3>	960	=item L<AnyEvent::IRC>
690		961
691	AnyEvent based IRC client module family.	962	AnyEvent based IRC client module family (replacing the older Net::IRC3).
692		963
693	=item L<Net::XMPP2>	964	=item L<Net::XMPP2>
694		965
695	AnyEvent based XMPP (Jabber protocol) module family.	966	AnyEvent based XMPP (Jabber protocol) module family.
696		967
…		…
705		976
706	=item L<Coro>	977	=item L<Coro>
707		978
708	Has special support for AnyEvent via L<Coro::AnyEvent>.	979	Has special support for AnyEvent via L<Coro::AnyEvent>.
709		980
710	=item L<AnyEvent::AIO>, L<IO::AIO>
711
712	Truly asynchronous I/O, should be in the toolbox of every event
713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714	together.
715
716	=item L<AnyEvent::BDB>, L<BDB>
717
718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719	IO::AIO and AnyEvent together.
720
721	=item L<IO::Lambda>	981	=item L<IO::Lambda>
722		982
723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	983	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724		984
725	=back	985	=back
…		…
727	=cut	987	=cut
728		988
729	package AnyEvent;	989	package AnyEvent;
730		990
731	no warnings;	991	no warnings;
732	use strict;	992	use strict qw(vars subs);
733		993
734	use Carp;	994	use Carp;
735		995
736	our $VERSION = '4.03';	996	our $VERSION = 4.8;
737	our $MODEL;	997	our $MODEL;
738		998
739	our $AUTOLOAD;	999	our $AUTOLOAD;
740	our @ISA;	1000	our @ISA;
741		1001
742	our @REGISTRY;	1002	our @REGISTRY;
		1003
		1004	our $WIN32;
		1005
		1006	BEGIN {
		1007	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1008	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1009
		1010	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1011	if ${^TAINT};
		1012	}
743		1013
744	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1014	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
745		1015
746	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1016	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
747		1017
…		…
764	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1034	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
765	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1035	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
766	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1036	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767	[Wx:: => AnyEvent::Impl::POE::],	1037	[Wx:: => AnyEvent::Impl::POE::],
768	[Prima:: => AnyEvent::Impl::POE::],	1038	[Prima:: => AnyEvent::Impl::POE::],
		1039	# IO::Async is just too broken - we would need workaorunds for its
		1040	# byzantine signal and broken child handling, among others.
		1041	# IO::Async is rather hard to detect, as it doesn't have any
		1042	# obvious default class.
		1043	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1044	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1045	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
769	);	1046	);
770		1047
771	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1048	our %method = map +($_ => 1),
		1049	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
772		1050
773	our @post_detect;	1051	our @post_detect;
774		1052
775	sub post_detect(&) {	1053	sub post_detect(&) {
776	my ($cb) = @_;	1054	my ($cb) = @_;
…		…
781	1	1059	1
782	} else {	1060	} else {
783	push @post_detect, $cb;	1061	push @post_detect, $cb;
784		1062
785	defined wantarray	1063	defined wantarray
786	? bless \$cb, "AnyEvent::Util::PostDetect"	1064	? bless \$cb, "AnyEvent::Util::postdetect"
787	: ()	1065	: ()
788	}	1066	}
789	}	1067	}
790		1068
791	sub AnyEvent::Util::PostDetect::DESTROY {	1069	sub AnyEvent::Util::postdetect::DESTROY {
792	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1070	@post_detect = grep $_ != ${$_[0]}, @post_detect;
793	}	1071	}
794		1072
795	sub detect() {	1073	sub detect() {
796	unless ($MODEL) {	1074	unless ($MODEL) {
…		…
833	last;	1111	last;
834	}	1112	}
835	}	1113	}
836		1114
837	$MODEL	1115	$MODEL
838	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1116	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
839	}	1117	}
840	}	1118	}
841		1119
		1120	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1121
842	unshift @ISA, $MODEL;	1122	unshift @ISA, $MODEL;
843	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1123
		1124	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
844		1125
845	(shift @post_detect)->() while @post_detect;	1126	(shift @post_detect)->() while @post_detect;
846	}	1127	}
847		1128
848	$MODEL	1129	$MODEL
…		…
858		1139
859	my $class = shift;	1140	my $class = shift;
860	$class->$func (@_);	1141	$class->$func (@_);
861	}	1142	}
862		1143
		1144	# utility function to dup a filehandle. this is used by many backends
		1145	# to support binding more than one watcher per filehandle (they usually
		1146	# allow only one watcher per fd, so we dup it to get a different one).
		1147	sub _dupfh($$;$$) {
		1148	my ($poll, $fh, $r, $w) = @_;
		1149
		1150	# cygwin requires the fh mode to be matching, unix doesn't
		1151	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1152	: $poll eq "w" ? ($w, ">")
		1153	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1154
		1155	open my $fh2, "$mode&" . fileno $fh
		1156	or die "cannot dup() filehandle: $!,";
		1157
		1158	# we assume CLOEXEC is already set by perl in all important cases
		1159
		1160	($fh2, $rw)
		1161	}
		1162
863	package AnyEvent::Base;	1163	package AnyEvent::Base;
864		1164
		1165	# default implementations for many methods
		1166
		1167	BEGIN {
		1168	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1169	*_time = \&Time::HiRes::time;
		1170	# if (eval "use POSIX (); (POSIX::times())...
		1171	} else {
		1172	*_time = sub { time }; # epic fail
		1173	}
		1174	}
		1175
		1176	sub time { _time }
		1177	sub now { _time }
		1178	sub now_update { }
		1179
865	# default implementation for ->condvar	1180	# default implementation for ->condvar
866		1181
867	sub condvar {	1182	sub condvar {
868	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1183	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
869	}	1184	}
870		1185
871	# default implementation for ->signal	1186	# default implementation for ->signal
872		1187
873	our %SIG_CB;	1188	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1189
		1190	sub _signal_exec {
		1191	sysread $SIGPIPE_R, my $dummy, 4;
		1192
		1193	while (%SIG_EV) {
		1194	for (keys %SIG_EV) {
		1195	delete $SIG_EV{$_};
		1196	$_->() for values %{ $SIG_CB{$_} || {} };
		1197	}
		1198	}
		1199	}
874		1200
875	sub signal {	1201	sub signal {
876	my (undef, %arg) = @_;	1202	my (undef, %arg) = @_;
877		1203
		1204	unless ($SIGPIPE_R) {
		1205	require Fcntl;
		1206
		1207	if (AnyEvent::WIN32) {
		1208	require AnyEvent::Util;
		1209
		1210	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1211	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1212	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1213	} else {
		1214	pipe $SIGPIPE_R, $SIGPIPE_W;
		1215	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1216	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1217
		1218	# not strictly required, as $^F is normally 2, but let's make sure...
		1219	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1220	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1221	}
		1222
		1223	$SIGPIPE_R
		1224	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1225
		1226	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1227	}
		1228
878	my $signal = uc $arg{signal}	1229	my $signal = uc $arg{signal}
879	or Carp::croak "required option 'signal' is missing";	1230	or Carp::croak "required option 'signal' is missing";
880		1231
881	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1232	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
882	$SIG{$signal} ||= sub {	1233	$SIG{$signal} ||= sub {
883	$_->() for values %{ $SIG_CB{$signal} || {} };	1234	local $!;
		1235	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1236	undef $SIG_EV{$signal};
884	};	1237	};
885		1238
886	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1239	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
887	}	1240	}
888		1241
889	sub AnyEvent::Base::Signal::DESTROY {	1242	sub AnyEvent::Base::signal::DESTROY {
890	my ($signal, $cb) = @{$_[0]};	1243	my ($signal, $cb) = @{$_[0]};
891		1244
892	delete $SIG_CB{$signal}{$cb};	1245	delete $SIG_CB{$signal}{$cb};
893		1246
		1247	# delete doesn't work with older perls - they then
		1248	# print weird messages, or just unconditionally exit
		1249	# instead of getting the default action.
894	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1250	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
895	}	1251	}
896		1252
897	# default implementation for ->child	1253	# default implementation for ->child
898		1254
899	our %PID_CB;	1255	our %PID_CB;
900	our $CHLD_W;	1256	our $CHLD_W;
901	our $CHLD_DELAY_W;	1257	our $CHLD_DELAY_W;
902	our $PID_IDLE;
903	our $WNOHANG;	1258	our $WNOHANG;
904		1259
905	sub _child_wait {	1260	sub _sigchld {
906	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1261	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
907	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1262	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
908	(values %{ $PID_CB{0} || {} });	1263	(values %{ $PID_CB{0} || {} });
909	}	1264	}
910
911	undef $PID_IDLE;
912	}
913
914	sub _sigchld {
915	# make sure we deliver these changes "synchronous" with the event loop.
916	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
917	undef $CHLD_DELAY_W;
918	&_child_wait;
919	});
920	}	1265	}
921		1266
922	sub child {	1267	sub child {
923	my (undef, %arg) = @_;	1268	my (undef, %arg) = @_;
924		1269
925	defined (my $pid = $arg{pid} + 0)	1270	defined (my $pid = $arg{pid} + 0)
926	or Carp::croak "required option 'pid' is missing";	1271	or Carp::croak "required option 'pid' is missing";
927		1272
928	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1273	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
929		1274
930	unless ($WNOHANG) {
931	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1275	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
932	}
933		1276
934	unless ($CHLD_W) {	1277	unless ($CHLD_W) {
935	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1278	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
936	# child could be a zombie already, so make at least one round	1279	# child could be a zombie already, so make at least one round
937	&_sigchld;	1280	&_sigchld;
938	}	1281	}
939		1282
940	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1283	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
941	}	1284	}
942		1285
943	sub AnyEvent::Base::Child::DESTROY {	1286	sub AnyEvent::Base::child::DESTROY {
944	my ($pid, $cb) = @{$_[0]};	1287	my ($pid, $cb) = @{$_[0]};
945		1288
946	delete $PID_CB{$pid}{$cb};	1289	delete $PID_CB{$pid}{$cb};
947	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1290	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
948		1291
949	undef $CHLD_W unless keys %PID_CB;	1292	undef $CHLD_W unless keys %PID_CB;
		1293	}
		1294
		1295	# idle emulation is done by simply using a timer, regardless
		1296	# of whether the process is idle or not, and not letting
		1297	# the callback use more than 50% of the time.
		1298	sub idle {
		1299	my (undef, %arg) = @_;
		1300
		1301	my ($cb, $w, $rcb) = $arg{cb};
		1302
		1303	$rcb = sub {
		1304	if ($cb) {
		1305	$w = _time;
		1306	&$cb;
		1307	$w = _time - $w;
		1308
		1309	# never use more then 50% of the time for the idle watcher,
		1310	# within some limits
		1311	$w = 0.0001 if $w < 0.0001;
		1312	$w = 5 if $w > 5;
		1313
		1314	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1315	} else {
		1316	# clean up...
		1317	undef $w;
		1318	undef $rcb;
		1319	}
		1320	};
		1321
		1322	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1323
		1324	bless \\$cb, "AnyEvent::Base::idle"
		1325	}
		1326
		1327	sub AnyEvent::Base::idle::DESTROY {
		1328	undef $${$_[0]};
950	}	1329	}
951		1330
952	package AnyEvent::CondVar;	1331	package AnyEvent::CondVar;
953		1332
954	our @ISA = AnyEvent::CondVar::Base::;	1333	our @ISA = AnyEvent::CondVar::Base::;
…		…
1006	}	1385	}
1007		1386
1008	# undocumented/compatibility with pre-3.4	1387	# undocumented/compatibility with pre-3.4
1009	*broadcast = \&send;	1388	*broadcast = \&send;
1010	*wait = \&_wait;	1389	*wait = \&_wait;
		1390
		1391	=head1 ERROR AND EXCEPTION HANDLING
		1392
		1393	In general, AnyEvent does not do any error handling - it relies on the
		1394	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1395	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1396	checking of all AnyEvent methods, however, which is highly useful during
		1397	development.
		1398
		1399	As for exception handling (i.e. runtime errors and exceptions thrown while
		1400	executing a callback), this is not only highly event-loop specific, but
		1401	also not in any way wrapped by this module, as this is the job of the main
		1402	program.
		1403
		1404	The pure perl event loop simply re-throws the exception (usually
		1405	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1406	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1407	so on.
		1408
		1409	=head1 ENVIRONMENT VARIABLES
		1410
		1411	The following environment variables are used by this module or its
		1412	submodules.
		1413
		1414	Note that AnyEvent will remove I<all> environment variables starting with
		1415	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1416	enabled.
		1417
		1418	=over 4
		1419
		1420	=item C<PERL_ANYEVENT_VERBOSE>
		1421
		1422	By default, AnyEvent will be completely silent except in fatal
		1423	conditions. You can set this environment variable to make AnyEvent more
		1424	talkative.
		1425
		1426	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1427	conditions, such as not being able to load the event model specified by
		1428	C<PERL_ANYEVENT_MODEL>.
		1429
		1430	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1431	model it chooses.
		1432
		1433	=item C<PERL_ANYEVENT_STRICT>
		1434
		1435	AnyEvent does not do much argument checking by default, as thorough
		1436	argument checking is very costly. Setting this variable to a true value
		1437	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1438	check the arguments passed to most method calls. If it finds any problems,
		1439	it will croak.
		1440
		1441	In other words, enables "strict" mode.
		1442
		1443	Unlike C<use strict>, it is definitely recommended to keep it off in
		1444	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1445	developing programs can be very useful, however.
		1446
		1447	=item C<PERL_ANYEVENT_MODEL>
		1448
		1449	This can be used to specify the event model to be used by AnyEvent, before
		1450	auto detection and -probing kicks in. It must be a string consisting
		1451	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1452	and the resulting module name is loaded and if the load was successful,
		1453	used as event model. If it fails to load AnyEvent will proceed with
		1454	auto detection and -probing.
		1455
		1456	This functionality might change in future versions.
		1457
		1458	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1459	could start your program like this:
		1460
		1461	PERL_ANYEVENT_MODEL=Perl perl ...
		1462
		1463	=item C<PERL_ANYEVENT_PROTOCOLS>
		1464
		1465	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1466	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1467	of auto probing).
		1468
		1469	Must be set to a comma-separated list of protocols or address families,
		1470	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1471	used, and preference will be given to protocols mentioned earlier in the
		1472	list.
		1473
		1474	This variable can effectively be used for denial-of-service attacks
		1475	against local programs (e.g. when setuid), although the impact is likely
		1476	small, as the program has to handle conenction and other failures anyways.
		1477
		1478	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1479	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1480	- only support IPv4, never try to resolve or contact IPv6
		1481	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1482	IPv6, but prefer IPv6 over IPv4.
		1483
		1484	=item C<PERL_ANYEVENT_EDNS0>
		1485
		1486	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1487	for DNS. This extension is generally useful to reduce DNS traffic, but
		1488	some (broken) firewalls drop such DNS packets, which is why it is off by
		1489	default.
		1490
		1491	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1492	EDNS0 in its DNS requests.
		1493
		1494	=item C<PERL_ANYEVENT_MAX_FORKS>
		1495
		1496	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1497	will create in parallel.
		1498
		1499	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1500
		1501	The default value for the C<max_outstanding> parameter for the default DNS
		1502	resolver - this is the maximum number of parallel DNS requests that are
		1503	sent to the DNS server.
		1504
		1505	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1506
		1507	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1508	configuration) in the default resolver. When set to the empty string, no
		1509	default config will be used.
		1510
		1511	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1512
		1513	When neither C<ca_file> nor C<ca_path> was specified during
		1514	L<AnyEvent::TLS> context creation, and either of these environment
		1515	variables exist, they will be used to specify CA certificate locations
		1516	instead of a system-dependent default.
		1517
		1518	=back
1011		1519
1012	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1520	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1013		1521
1014	This is an advanced topic that you do not normally need to use AnyEvent in	1522	This is an advanced topic that you do not normally need to use AnyEvent in
1015	a module. This section is only of use to event loop authors who want to	1523	a module. This section is only of use to event loop authors who want to
…		…
1049		1557
1050	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1558	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1051	condition variables: code blocking while waiting for a condition will	1559	condition variables: code blocking while waiting for a condition will
1052	C<die>. This still works with most modules/usages, and blocking calls must	1560	C<die>. This still works with most modules/usages, and blocking calls must
1053	not be done in an interactive application, so it makes sense.	1561	not be done in an interactive application, so it makes sense.
1054
1055	=head1 ENVIRONMENT VARIABLES
1056
1057	The following environment variables are used by this module:
1058
1059	=over 4
1060
1061	=item C<PERL_ANYEVENT_VERBOSE>
1062
1063	By default, AnyEvent will be completely silent except in fatal
1064	conditions. You can set this environment variable to make AnyEvent more
1065	talkative.
1066
1067	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1068	conditions, such as not being able to load the event model specified by
1069	C<PERL_ANYEVENT_MODEL>.
1070
1071	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1072	model it chooses.
1073
1074	=item C<PERL_ANYEVENT_MODEL>
1075
1076	This can be used to specify the event model to be used by AnyEvent, before
1077	auto detection and -probing kicks in. It must be a string consisting
1078	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1079	and the resulting module name is loaded and if the load was successful,
1080	used as event model. If it fails to load AnyEvent will proceed with
1081	auto detection and -probing.
1082
1083	This functionality might change in future versions.
1084
1085	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1086	could start your program like this:
1087
1088	PERL_ANYEVENT_MODEL=Perl perl ...
1089
1090	=item C<PERL_ANYEVENT_PROTOCOLS>
1091
1092	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1093	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1094	of auto probing).
1095
1096	Must be set to a comma-separated list of protocols or address families,
1097	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1098	used, and preference will be given to protocols mentioned earlier in the
1099	list.
1100
1101	This variable can effectively be used for denial-of-service attacks
1102	against local programs (e.g. when setuid), although the impact is likely
1103	small, as the program has to handle connection errors already-
1104
1105	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1106	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1107	- only support IPv4, never try to resolve or contact IPv6
1108	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1109	IPv6, but prefer IPv6 over IPv4.
1110
1111	=item C<PERL_ANYEVENT_EDNS0>
1112
1113	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1114	for DNS. This extension is generally useful to reduce DNS traffic, but
1115	some (broken) firewalls drop such DNS packets, which is why it is off by
1116	default.
1117
1118	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1119	EDNS0 in its DNS requests.
1120
1121	=back
1122		1562
1123	=head1 EXAMPLE PROGRAM	1563	=head1 EXAMPLE PROGRAM
1124		1564
1125	The following program uses an I/O watcher to read data from STDIN, a timer	1565	The following program uses an I/O watcher to read data from STDIN, a timer
1126	to display a message once per second, and a condition variable to quit the	1566	to display a message once per second, and a condition variable to quit the
…		…
1320	watcher.	1760	watcher.
1321		1761
1322	=head3 Results	1762	=head3 Results
1323		1763
1324	name watchers bytes create invoke destroy comment	1764	name watchers bytes create invoke destroy comment
1325	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1765	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1326	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1766	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1327	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1767	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1328	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1768	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1329	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1769	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1330	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1770	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1771	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1772	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1331	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1773	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1332	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1774	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1333	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1775	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1334	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1776	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1335		1777
1336	=head3 Discussion	1778	=head3 Discussion
1337		1779
1338	The benchmark does I<not> measure scalability of the event loop very	1780	The benchmark does I<not> measure scalability of the event loop very
1339	well. For example, a select-based event loop (such as the pure perl one)	1781	well. For example, a select-based event loop (such as the pure perl one)
…		…
1364	performance becomes really bad with lots of file descriptors (and few of	1806	performance becomes really bad with lots of file descriptors (and few of
1365	them active), of course, but this was not subject of this benchmark.	1807	them active), of course, but this was not subject of this benchmark.
1366		1808
1367	The C<Event> module has a relatively high setup and callback invocation	1809	The C<Event> module has a relatively high setup and callback invocation
1368	cost, but overall scores in on the third place.	1810	cost, but overall scores in on the third place.
		1811
		1812	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1813	when using its pure perl backend.
1369		1814
1370	C<Glib>'s memory usage is quite a bit higher, but it features a	1815	C<Glib>'s memory usage is quite a bit higher, but it features a
1371	faster callback invocation and overall ends up in the same class as	1816	faster callback invocation and overall ends up in the same class as
1372	C<Event>. However, Glib scales extremely badly, doubling the number of	1817	C<Event>. However, Glib scales extremely badly, doubling the number of
1373	watchers increases the processing time by more than a factor of four,	1818	watchers increases the processing time by more than a factor of four,
…		…
1451	it to another server. This includes deleting the old timeout and creating	1896	it to another server. This includes deleting the old timeout and creating
1452	a new one that moves the timeout into the future.	1897	a new one that moves the timeout into the future.
1453		1898
1454	=head3 Results	1899	=head3 Results
1455		1900
1456	name sockets create request	1901	name sockets create request
1457	EV 20000 69.01 11.16	1902	EV 20000 69.01 11.16
1458	Perl 20000 73.32 35.87	1903	Perl 20000 73.32 35.87
		1904	IOAsync 20000 157.00 98.14 epoll
		1905	IOAsync 20000 159.31 616.06 poll
1459	Event 20000 212.62 257.32	1906	Event 20000 212.62 257.32
1460	Glib 20000 651.16 1896.30	1907	Glib 20000 651.16 1896.30
1461	POE 20000 349.67 12317.24 uses POE::Loop::Event	1908	POE 20000 349.67 12317.24 uses POE::Loop::Event
1462		1909
1463	=head3 Discussion	1910	=head3 Discussion
1464		1911
1465	This benchmark I<does> measure scalability and overall performance of the	1912	This benchmark I<does> measure scalability and overall performance of the
1466	particular event loop.	1913	particular event loop.
…		…
1468	EV is again fastest. Since it is using epoll on my system, the setup time	1915	EV is again fastest. Since it is using epoll on my system, the setup time
1469	is relatively high, though.	1916	is relatively high, though.
1470		1917
1471	Perl surprisingly comes second. It is much faster than the C-based event	1918	Perl surprisingly comes second. It is much faster than the C-based event
1472	loops Event and Glib.	1919	loops Event and Glib.
		1920
		1921	IO::Async performs very well when using its epoll backend, and still quite
		1922	good compared to Glib when using its pure perl backend.
1473		1923
1474	Event suffers from high setup time as well (look at its code and you will	1924	Event suffers from high setup time as well (look at its code and you will
1475	understand why). Callback invocation also has a high overhead compared to	1925	understand why). Callback invocation also has a high overhead compared to
1476	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1926	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1477	uses select or poll in basically all documented configurations.	1927	uses select or poll in basically all documented configurations.
…		…
1540	=item * C-based event loops perform very well with small number of	1990	=item * C-based event loops perform very well with small number of
1541	watchers, as the management overhead dominates.	1991	watchers, as the management overhead dominates.
1542		1992
1543	=back	1993	=back
1544		1994
		1995	=head2 THE IO::Lambda BENCHMARK
		1996
		1997	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1998	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1999	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2000	shouldn't come as a surprise to anybody). As such, the benchmark is
		2001	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2002	very optimal. But how would AnyEvent compare when used without the extra
		2003	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2004
		2005	The benchmark itself creates an echo-server, and then, for 500 times,
		2006	connects to the echo server, sends a line, waits for the reply, and then
		2007	creates the next connection. This is a rather bad benchmark, as it doesn't
		2008	test the efficiency of the framework or much non-blocking I/O, but it is a
		2009	benchmark nevertheless.
		2010
		2011	name runtime
		2012	Lambda/select 0.330 sec
		2013	+ optimized 0.122 sec
		2014	Lambda/AnyEvent 0.327 sec
		2015	+ optimized 0.138 sec
		2016	Raw sockets/select 0.077 sec
		2017	POE/select, components 0.662 sec
		2018	POE/select, raw sockets 0.226 sec
		2019	POE/select, optimized 0.404 sec
		2020
		2021	AnyEvent/select/nb 0.085 sec
		2022	AnyEvent/EV/nb 0.068 sec
		2023	+state machine 0.134 sec
		2024
		2025	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2026	benchmarks actually make blocking connects and use 100% blocking I/O,
		2027	defeating the purpose of an event-based solution. All of the newly
		2028	written AnyEvent benchmarks use 100% non-blocking connects (using
		2029	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2030	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2031	generally require a lot more bookkeeping and event handling than blocking
		2032	connects (which involve a single syscall only).
		2033
		2034	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2035	offers similar expressive power as POE and IO::Lambda, using conventional
		2036	Perl syntax. This means that both the echo server and the client are 100%
		2037	non-blocking, further placing it at a disadvantage.
		2038
		2039	As you can see, the AnyEvent + EV combination even beats the
		2040	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2041	backend easily beats IO::Lambda and POE.
		2042
		2043	And even the 100% non-blocking version written using the high-level (and
		2044	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2045	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2046	in a non-blocking way.
		2047
		2048	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2049	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2050	part of the IO::lambda distribution and were used without any changes.
		2051
		2052
		2053	=head1 SIGNALS
		2054
		2055	AnyEvent currently installs handlers for these signals:
		2056
		2057	=over 4
		2058
		2059	=item SIGCHLD
		2060
		2061	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2062	emulation for event loops that do not support them natively. Also, some
		2063	event loops install a similar handler.
		2064
		2065	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2066	reset it to default, to avoid losing child exit statuses.
		2067
		2068	=item SIGPIPE
		2069
		2070	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2071	when AnyEvent gets loaded.
		2072
		2073	The rationale for this is that AnyEvent users usually do not really depend
		2074	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2075	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2076	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2077	some random socket.
		2078
		2079	The rationale for installing a no-op handler as opposed to ignoring it is
		2080	that this way, the handler will be restored to defaults on exec.
		2081
		2082	Feel free to install your own handler, or reset it to defaults.
		2083
		2084	=back
		2085
		2086	=cut
		2087
		2088	undef $SIG{CHLD}
		2089	if $SIG{CHLD} eq 'IGNORE';
		2090
		2091	$SIG{PIPE} = sub { }
		2092	unless defined $SIG{PIPE};
1545		2093
1546	=head1 FORK	2094	=head1 FORK
1547		2095
1548	Most event libraries are not fork-safe. The ones who are usually are	2096	Most event libraries are not fork-safe. The ones who are usually are
1549	because they rely on inefficient but fork-safe C<select> or C<poll>	2097	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1563	specified in the variable.	2111	specified in the variable.
1564		2112
1565	You can make AnyEvent completely ignore this variable by deleting it	2113	You can make AnyEvent completely ignore this variable by deleting it
1566	before the first watcher gets created, e.g. with a C<BEGIN> block:	2114	before the first watcher gets created, e.g. with a C<BEGIN> block:
1567		2115
1568	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2116	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1569		2117
1570	use AnyEvent;	2118	use AnyEvent;
1571		2119
1572	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2120	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1573	be used to probe what backend is used and gain other information (which is	2121	be used to probe what backend is used and gain other information (which is
1574	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2122	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2123	$ENV{PERL_ANYEVENT_STRICT}.
		2124
		2125	Note that AnyEvent will remove I<all> environment variables starting with
		2126	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2127	enabled.
		2128
		2129
		2130	=head1 BUGS
		2131
		2132	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2133	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2134	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2135	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2136	pronounced).
1575		2137
1576		2138
1577	=head1 SEE ALSO	2139	=head1 SEE ALSO
1578		2140
1579	Utility functions: L<AnyEvent::Util>.	2141	Utility functions: L<AnyEvent::Util>.
…		…
1596	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2158	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1597		2159
1598		2160
1599	=head1 AUTHOR	2161	=head1 AUTHOR
1600		2162
1601	Marc Lehmann <schmorp@schmorp.de>	2163	Marc Lehmann <schmorp@schmorp.de>
1602	http://home.schmorp.de/	2164	http://home.schmorp.de/
1603		2165
1604	=cut	2166	=cut
1605		2167
1606	1	2168	1
1607		2169

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