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Revision 1.143 by root, Wed May 28 23:57:38 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
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	148	is in control).
125		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
126	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
127	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
128	to it).	158	to it).
129		159
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		164
135	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
136		166
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
139	undef $w;	169	undef $w;
140	});	170	});
141		171
142	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,
143	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
144	declared.	174	declared.
145		175
146	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
147		177
148	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
149	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
150		180
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
154	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.
155	becomes ready.
156		192
157	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
160		196
…		…
164		200
165	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
166	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
167	handles.	203	handles.
168		204
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	210	warn "read: $input\n";
175	undef $w;	211	undef $w;
176	});	212	});
177		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
178	=head2 TIME WATCHERS	237	=head2 TIME WATCHERS
179		238
180	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 >>
181	method with the following mandatory arguments:	240	method with the following mandatory arguments:
182		241
…		…
186		245
187	Although the callback might get passed parameters, their value and	246	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	247	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	248	callbacks cannot use arguments passed to time watcher callbacks.
190		249
191	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
192	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
193	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.
194		255
195	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.
196		259
197	# fire an event after 7.7 seconds	260	Example: fire an event after 7.7 seconds.
		261
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	262	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	263	warn "timeout\n";
200	});	264	});
201		265
202	# to cancel the timer:	266	# to cancel the timer:
203	undef $w;	267	undef $w;
204		268
205	Example 2:
206
207	# 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.
208	my $w;
209		270
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	271	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		272	warn "timeout\n";
213	};	273	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		274
218	=head3 TIMING ISSUES	275	=head3 TIMING ISSUES
219		276
220	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
221	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
…		…
243		300
244	This returns the "current wallclock time" as a fractional number of	301	This returns the "current wallclock time" as a fractional number of
245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>	302	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
246	return, and the result is guaranteed to be compatible with those).	303	return, and the result is guaranteed to be compatible with those).
247		304
248	It progresses independently of any event loop processing.	305	It progresses independently of any event loop processing, i.e. each call
249		306	will check the system clock, which usually gets updated frequently.
250	In almost all cases (in all cases if you don't care), this is the function
251	to call when you want to know the current time.
252		307
253	=item AnyEvent->now	308	=item AnyEvent->now
254		309
255	This also returns the "current wallclock time", but unlike C<time>, above,	310	This also returns the "current wallclock time", but unlike C<time>, above,
256	this value might change only once per event loop iteration, depending on	311	this value might change only once per event loop iteration, depending on
257	the event loop (most return the same time as C<time>, above). This is the	312	the event loop (most return the same time as C<time>, above). This is the
258	time that AnyEvent timers get scheduled against.	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.
259		324
260	For a practical example of when these times differ, consider L<Event::Lib>	325	For a practical example of when these times differ, consider L<Event::Lib>
261	and L<EV> and the following set-up:	326	and L<EV> and the following set-up:
262		327
263	The event loop is running and has just invoked one of your callback at	328	The event loop is running and has just invoked one of your callback at
…		…
268		333
269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will	334	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
270	both return C<501>, because that is the current time, and the timer will	335	both return C<501>, because that is the current time, and the timer will
271	be scheduled to fire at time=504 (C<501> + C<3>).	336	be scheduled to fire at time=504 (C<501> + C<3>).
272		337
273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current	338	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the	339	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
275	last event processing phase started. With L<EV>, your timer gets scheduled	340	last event processing phase started. With L<EV>, your timer gets scheduled
276	to run at time=503 (C<500> + C<3>).	341	to run at time=503 (C<500> + C<3>).
277		342
278	In one sense, L<Event::Lib> is more exact, as it uses the current time	343	In one sense, L<Event::Lib> is more exact, as it uses the current time
279	regardless of any delays introduced by event processing. However, most	344	regardless of any delays introduced by event processing. However, most
280	callbacks do not expect large delays in processing, so this causes a	345	callbacks do not expect large delays in processing, so this causes a
281	higher drift (and a lot more syscalls to get the current time).	346	higher drift (and a lot more system calls to get the current time).
282		347
283	In another sense, L<EV> is more exact, as your timer will be scheduled at	348	In another sense, L<EV> is more exact, as your timer will be scheduled at
284	the same time, regardless of how long event processing actually took.	349	the same time, regardless of how long event processing actually took.
285		350
286	In either case, if you care (and in most cases, you don't), then you	351	In either case, if you care (and in most cases, you don't), then you
287	can get whatever behaviour you want with any event loop, by taking the	352	can get whatever behaviour you want with any event loop, by taking the
288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	353	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
289	account.	354	account.
290		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
291	=back	371	=back
292		372
293	=head2 SIGNAL WATCHERS	373	=head2 SIGNAL WATCHERS
294		374
295	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
296	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
297	be invoked whenever a signal occurs.	377	callback to be invoked whenever a signal occurs.
298		378
299	Although the callback might get passed parameters, their value and	379	Although the callback might get passed parameters, their value and
300	presence is undefined and you cannot rely on them. Portable AnyEvent	380	presence is undefined and you cannot rely on them. Portable AnyEvent
301	callbacks cannot use arguments passed to signal watcher callbacks.	381	callbacks cannot use arguments passed to signal watcher callbacks.
302		382
…		…
318	=head2 CHILD PROCESS WATCHERS	398	=head2 CHILD PROCESS WATCHERS
319		399
320	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.
321		401
322	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
323	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
324	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
325	signal handler for C<SIGCHLD>. The callback will be called with the pid	405	any trace events (stopped/continued).
326	and exit status (as returned by waitpid), so unlike other watcher types,	406
327	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).
328		415
329	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
330	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
331	have exited already (and no SIGCHLD will be sent anymore).	418	have exited already (and no SIGCHLD will be sent anymore).
332		419
333	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
334	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
335	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.
336		426
337	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
338	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
339	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>).
340		431
341	Example: fork a process and wait for it	432	Example: fork a process and wait for it
342		433
343	my $done = AnyEvent->condvar;	434	my $done = AnyEvent->condvar;
344		435
345	my $pid = fork or exit 5;	436	my $pid = fork or exit 5;
346		437
347	my $w = AnyEvent->child (	438	my $w = AnyEvent->child (
348	pid => $pid,	439	pid => $pid,
349	cb => sub {	440	cb => sub {
350	my ($pid, $status) = @_;	441	my ($pid, $status) = @_;
351	warn "pid $pid exited with status $status";	442	warn "pid $pid exited with status $status";
352	$done->send;	443	$done->send;
353	},	444	},
354	);	445	);
355		446
356	# do something else, then wait for process exit	447	# do something else, then wait for process exit
357	$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	});
358		484
359	=head2 CONDITION VARIABLES	485	=head2 CONDITION VARIABLES
360		486
361	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
362	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
…		…
368	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
369	because they represent a condition that must become true.	495	because they represent a condition that must become true.
370		496
371	Condition variables can be created by calling the C<< AnyEvent->condvar	497	Condition variables can be created by calling the C<< AnyEvent->condvar
372	>> method, usually without arguments. The only argument pair allowed is	498	>> method, usually without arguments. The only argument pair allowed is
		499
373	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
374	becomes true.	501	becomes true, with the condition variable as the first argument (but not
		502	the results).
375		503
376	After creation, the condition variable is "false" until it becomes "true"	504	After creation, the condition variable is "false" until it becomes "true"
377	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
378	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<<
379	->send >> method).	507	->send >> method).
…		…
435		563
436	my $done = AnyEvent->condvar;	564	my $done = AnyEvent->condvar;
437	my $delay = AnyEvent->timer (after => 5, cb => $done);	565	my $delay = AnyEvent->timer (after => 5, cb => $done);
438	$done->recv;	566	$done->recv;
439		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
440	=head3 METHODS FOR PRODUCERS	585	=head3 METHODS FOR PRODUCERS
441		586
442	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
443	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
444	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
…		…
477		622
478	=item $cv->begin ([group callback])	623	=item $cv->begin ([group callback])
479		624
480	=item $cv->end	625	=item $cv->end
481		626
482	These two methods are EXPERIMENTAL and MIGHT CHANGE.
483
484	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
485	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
486	to use a condition variable for the whole process.	629	to use a condition variable for the whole process.
487		630
488	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
489	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
490	>>, 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
491	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
492	callback was set, C<send> will be called without any arguments.	635	callback was set, C<send> will be called without any arguments.
493		636
494	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:
495		668
496	my $cv = AnyEvent->condvar;	669	my $cv = AnyEvent->condvar;
497		670
498	my %result;	671	my %result;
499	$cv->begin (sub { $cv->send (\%result) });	672	$cv->begin (sub { $cv->send (\%result) });
…		…
519	loop, which serves two important purposes: first, it sets the callback	692	loop, which serves two important purposes: first, it sets the callback
520	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
521	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
522	doesn't execute once).	695	doesn't execute once).
523		696
524	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
525	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
526	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
527	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>.
528		702
529	=back	703	=back
530		704
531	=head3 METHODS FOR CONSUMERS	705	=head3 METHODS FOR CONSUMERS
532		706
…		…
577	=item $bool = $cv->ready	751	=item $bool = $cv->ready
578		752
579	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
580	C<croak> have been called.	754	C<croak> have been called.
581		755
582	=item $cb = $cv->cb ([new callback])	756	=item $cb = $cv->cb ($cb->($cv))
583		757
584	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
585	replaces it before doing so.	759	replaces it before doing so.
586		760
587	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
588	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
589	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.
590		765
591	=back	766	=back
592		767
593	=head1 GLOBAL VARIABLES AND FUNCTIONS	768	=head1 GLOBAL VARIABLES AND FUNCTIONS
594		769
…		…
611	AnyEvent::Impl::Tk based on Tk, very bad choice.	786	AnyEvent::Impl::Tk based on Tk, very bad choice.
612	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).
613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	788	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
614	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.
615		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
616	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
617	watching file handles. However, you can use WxWidgets through the	796	watching file handles. However, you can use WxWidgets through the
618	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
619	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
620	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
…		…
723	=item L<AnyEvent::Util>	902	=item L<AnyEvent::Util>
724		903
725	Contains various utility functions that replace often-used but blocking	904	Contains various utility functions that replace often-used but blocking
726	functions such as C<inet_aton> by event-/callback-based versions.	905	functions such as C<inet_aton> by event-/callback-based versions.
727		906
728	=item L<AnyEvent::Handle>
729
730	Provide read and write buffers and manages watchers for reads and writes.
731
732	=item L<AnyEvent::Socket>	907	=item L<AnyEvent::Socket>
733		908
734	Provides various utility functions for (internet protocol) sockets,	909	Provides various utility functions for (internet protocol) sockets,
735	addresses and name resolution. Also functions to create non-blocking tcp	910	addresses and name resolution. Also functions to create non-blocking tcp
736	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.
737		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
738	=item L<AnyEvent::DNS>	919	=item L<AnyEvent::DNS>
739		920
740	Provides rich asynchronous DNS resolver capabilities.	921	Provides rich asynchronous DNS resolver capabilities.
741		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
742	=item L<AnyEvent::HTTPD>	928	=item L<AnyEvent::HTTPD>
743		929
744	Provides a simple web application server framework.	930	Provides a simple web application server framework.
745		931
746	=item L<AnyEvent::FastPing>	932	=item L<AnyEvent::FastPing>
747		933
748	The fastest ping in the west.	934	The fastest ping in the west.
749		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
750	=item L<Net::IRC3>	960	=item L<AnyEvent::IRC>
751		961
752	AnyEvent based IRC client module family.	962	AnyEvent based IRC client module family (replacing the older Net::IRC3).
753		963
754	=item L<Net::XMPP2>	964	=item L<Net::XMPP2>
755		965
756	AnyEvent based XMPP (Jabber protocol) module family.	966	AnyEvent based XMPP (Jabber protocol) module family.
757		967
…		…
766		976
767	=item L<Coro>	977	=item L<Coro>
768		978
769	Has special support for AnyEvent via L<Coro::AnyEvent>.	979	Has special support for AnyEvent via L<Coro::AnyEvent>.
770		980
771	=item L<AnyEvent::AIO>, L<IO::AIO>
772
773	Truly asynchronous I/O, should be in the toolbox of every event
774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
775	together.
776
777	=item L<AnyEvent::BDB>, L<BDB>
778
779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
780	IO::AIO and AnyEvent together.
781
782	=item L<IO::Lambda>	981	=item L<IO::Lambda>
783		982
784	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.
785		984
786	=back	985	=back
…		…
788	=cut	987	=cut
789		988
790	package AnyEvent;	989	package AnyEvent;
791		990
792	no warnings;	991	no warnings;
793	use strict;	992	use strict qw(vars subs);
794		993
795	use Carp;	994	use Carp;
796		995
797	our $VERSION = '4.05';	996	our $VERSION = 4.8;
798	our $MODEL;	997	our $MODEL;
799		998
800	our $AUTOLOAD;	999	our $AUTOLOAD;
801	our @ISA;	1000	our @ISA;
802		1001
803	our @REGISTRY;	1002	our @REGISTRY;
804		1003
805	our $WIN32;	1004	our $WIN32;
806		1005
807	BEGIN {	1006	BEGIN {
808	my $win32 = ! ! ($^O =~ /mswin32/i);	1007	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
809	eval "sub WIN32(){ $win32 }";	1008	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1009
		1010	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1011	if ${^TAINT};
810	}	1012	}
811		1013
812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1014	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
813		1015
814	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1016	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
…		…
832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1034	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1035	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1036	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
835	[Wx:: => AnyEvent::Impl::POE::],	1037	[Wx:: => AnyEvent::Impl::POE::],
836	[Prima:: => AnyEvent::Impl::POE::],	1038	[Prima:: => AnyEvent::Impl::POE::],
		1039	# IO::Async is just too broken - we would need workaorunds for its
		1040	# byzantine signal and broken child handling, among others.
		1041	# IO::Async is rather hard to detect, as it doesn't have any
		1042	# obvious default class.
		1043	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1044	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1045	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
837	);	1046	);
838		1047
839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1048	our %method = map +($_ => 1),
		1049	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
840		1050
841	our @post_detect;	1051	our @post_detect;
842		1052
843	sub post_detect(&) {	1053	sub post_detect(&) {
844	my ($cb) = @_;	1054	my ($cb) = @_;
…		…
849	1	1059	1
850	} else {	1060	} else {
851	push @post_detect, $cb;	1061	push @post_detect, $cb;
852		1062
853	defined wantarray	1063	defined wantarray
854	? bless \$cb, "AnyEvent::Util::PostDetect"	1064	? bless \$cb, "AnyEvent::Util::postdetect"
855	: ()	1065	: ()
856	}	1066	}
857	}	1067	}
858		1068
859	sub AnyEvent::Util::PostDetect::DESTROY {	1069	sub AnyEvent::Util::postdetect::DESTROY {
860	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1070	@post_detect = grep $_ != ${$_[0]}, @post_detect;
861	}	1071	}
862		1072
863	sub detect() {	1073	sub detect() {
864	unless ($MODEL) {	1074	unless ($MODEL) {
…		…
901	last;	1111	last;
902	}	1112	}
903	}	1113	}
904		1114
905	$MODEL	1115	$MODEL
906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1116	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
907	}	1117	}
908	}	1118	}
909		1119
		1120	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1121
910	unshift @ISA, $MODEL;	1122	unshift @ISA, $MODEL;
911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1123
		1124	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
912		1125
913	(shift @post_detect)->() while @post_detect;	1126	(shift @post_detect)->() while @post_detect;
914	}	1127	}
915		1128
916	$MODEL	1129	$MODEL
…		…
926		1139
927	my $class = shift;	1140	my $class = shift;
928	$class->$func (@_);	1141	$class->$func (@_);
929	}	1142	}
930		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
931	package AnyEvent::Base;	1163	package AnyEvent::Base;
932		1164
933	# default implementation for now and time	1165	# default implementations for many methods
934		1166
935	use Time::HiRes ();	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	}
936		1175
937	sub time { Time::HiRes::time }	1176	sub time { _time }
938	sub now { Time::HiRes::time }	1177	sub now { _time }
		1178	sub now_update { }
939		1179
940	# default implementation for ->condvar	1180	# default implementation for ->condvar
941		1181
942	sub condvar {	1182	sub condvar {
943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1183	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
944	}	1184	}
945		1185
946	# default implementation for ->signal	1186	# default implementation for ->signal
947		1187
948	our %SIG_CB;	1188	our ($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	}
949		1200
950	sub signal {	1201	sub signal {
951	my (undef, %arg) = @_;	1202	my (undef, %arg) = @_;
952		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
953	my $signal = uc $arg{signal}	1229	my $signal = uc $arg{signal}
954	or Carp::croak "required option 'signal' is missing";	1230	or Carp::croak "required option 'signal' is missing";
955		1231
956	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1232	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
957	$SIG{$signal} ||= sub {	1233	$SIG{$signal} ||= sub {
958	$_->() for values %{ $SIG_CB{$signal} || {} };	1234	local $!;
		1235	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1236	undef $SIG_EV{$signal};
959	};	1237	};
960		1238
961	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1239	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
962	}	1240	}
963		1241
964	sub AnyEvent::Base::Signal::DESTROY {	1242	sub AnyEvent::Base::signal::DESTROY {
965	my ($signal, $cb) = @{$_[0]};	1243	my ($signal, $cb) = @{$_[0]};
966		1244
967	delete $SIG_CB{$signal}{$cb};	1245	delete $SIG_CB{$signal}{$cb};
968		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.
969	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1250	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
970	}	1251	}
971		1252
972	# default implementation for ->child	1253	# default implementation for ->child
973		1254
974	our %PID_CB;	1255	our %PID_CB;
975	our $CHLD_W;	1256	our $CHLD_W;
976	our $CHLD_DELAY_W;	1257	our $CHLD_DELAY_W;
977	our $PID_IDLE;
978	our $WNOHANG;	1258	our $WNOHANG;
979		1259
980	sub _child_wait {	1260	sub _sigchld {
981	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1261	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
982	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1262	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
983	(values %{ $PID_CB{0} || {} });	1263	(values %{ $PID_CB{0} || {} });
984	}	1264	}
985
986	undef $PID_IDLE;
987	}
988
989	sub _sigchld {
990	# make sure we deliver these changes "synchronous" with the event loop.
991	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
992	undef $CHLD_DELAY_W;
993	&_child_wait;
994	});
995	}	1265	}
996		1266
997	sub child {	1267	sub child {
998	my (undef, %arg) = @_;	1268	my (undef, %arg) = @_;
999		1269
1000	defined (my $pid = $arg{pid} + 0)	1270	defined (my $pid = $arg{pid} + 0)
1001	or Carp::croak "required option 'pid' is missing";	1271	or Carp::croak "required option 'pid' is missing";
1002		1272
1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1273	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1004		1274
1005	unless ($WNOHANG) {
1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1275	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1007	}
1008		1276
1009	unless ($CHLD_W) {	1277	unless ($CHLD_W) {
1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1278	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1011	# child could be a zombie already, so make at least one round	1279	# child could be a zombie already, so make at least one round
1012	&_sigchld;	1280	&_sigchld;
1013	}	1281	}
1014		1282
1015	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1283	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1016	}	1284	}
1017		1285
1018	sub AnyEvent::Base::Child::DESTROY {	1286	sub AnyEvent::Base::child::DESTROY {
1019	my ($pid, $cb) = @{$_[0]};	1287	my ($pid, $cb) = @{$_[0]};
1020		1288
1021	delete $PID_CB{$pid}{$cb};	1289	delete $PID_CB{$pid}{$cb};
1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1290	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1023		1291
1024	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]};
1025	}	1329	}
1026		1330
1027	package AnyEvent::CondVar;	1331	package AnyEvent::CondVar;
1028		1332
1029	our @ISA = AnyEvent::CondVar::Base::;	1333	our @ISA = AnyEvent::CondVar::Base::;
…		…
1081	}	1385	}
1082		1386
1083	# undocumented/compatibility with pre-3.4	1387	# undocumented/compatibility with pre-3.4
1084	*broadcast = \&send;	1388	*broadcast = \&send;
1085	*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
1086		1519
1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1520	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1088		1521
1089	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
1090	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
…		…
1124		1557
1125	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
1126	condition variables: code blocking while waiting for a condition will	1559	condition variables: code blocking while waiting for a condition will
1127	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
1128	not be done in an interactive application, so it makes sense.	1561	not be done in an interactive application, so it makes sense.
1129
1130	=head1 ENVIRONMENT VARIABLES
1131
1132	The following environment variables are used by this module:
1133
1134	=over 4
1135
1136	=item C<PERL_ANYEVENT_VERBOSE>
1137
1138	By default, AnyEvent will be completely silent except in fatal
1139	conditions. You can set this environment variable to make AnyEvent more
1140	talkative.
1141
1142	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1143	conditions, such as not being able to load the event model specified by
1144	C<PERL_ANYEVENT_MODEL>.
1145
1146	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1147	model it chooses.
1148
1149	=item C<PERL_ANYEVENT_MODEL>
1150
1151	This can be used to specify the event model to be used by AnyEvent, before
1152	auto detection and -probing kicks in. It must be a string consisting
1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1154	and the resulting module name is loaded and if the load was successful,
1155	used as event model. If it fails to load AnyEvent will proceed with
1156	auto detection and -probing.
1157
1158	This functionality might change in future versions.
1159
1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1161	could start your program like this:
1162
1163	PERL_ANYEVENT_MODEL=Perl perl ...
1164
1165	=item C<PERL_ANYEVENT_PROTOCOLS>
1166
1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1169	of auto probing).
1170
1171	Must be set to a comma-separated list of protocols or address families,
1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1173	used, and preference will be given to protocols mentioned earlier in the
1174	list.
1175
1176	This variable can effectively be used for denial-of-service attacks
1177	against local programs (e.g. when setuid), although the impact is likely
1178	small, as the program has to handle connection errors already-
1179
1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1182	- only support IPv4, never try to resolve or contact IPv6
1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1184	IPv6, but prefer IPv6 over IPv4.
1185
1186	=item C<PERL_ANYEVENT_EDNS0>
1187
1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic, but
1190	some (broken) firewalls drop such DNS packets, which is why it is off by
1191	default.
1192
1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1194	EDNS0 in its DNS requests.
1195
1196	=item C<PERL_ANYEVENT_MAX_FORKS>
1197
1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1199	will create in parallel.
1200
1201	=back
1202		1562
1203	=head1 EXAMPLE PROGRAM	1563	=head1 EXAMPLE PROGRAM
1204		1564
1205	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
1206	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
…		…
1400	watcher.	1760	watcher.
1401		1761
1402	=head3 Results	1762	=head3 Results
1403		1763
1404	name watchers bytes create invoke destroy comment	1764	name watchers bytes create invoke destroy comment
1405	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
1406	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
1407	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
1408	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
1409	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
1410	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
1411	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
1412	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
1413	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
1414	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
1415		1777
1416	=head3 Discussion	1778	=head3 Discussion
1417		1779
1418	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
1419	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)
…		…
1444	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
1445	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.
1446		1808
1447	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
1448	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.
1449		1814
1450	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
1451	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
1452	C<Event>. However, Glib scales extremely badly, doubling the number of	1817	C<Event>. However, Glib scales extremely badly, doubling the number of
1453	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,
…		…
1531	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
1532	a new one that moves the timeout into the future.	1897	a new one that moves the timeout into the future.
1533		1898
1534	=head3 Results	1899	=head3 Results
1535		1900
1536	name sockets create request	1901	name sockets create request
1537	EV 20000 69.01 11.16	1902	EV 20000 69.01 11.16
1538	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
1539	Event 20000 212.62 257.32	1906	Event 20000 212.62 257.32
1540	Glib 20000 651.16 1896.30	1907	Glib 20000 651.16 1896.30
1541	POE 20000 349.67 12317.24 uses POE::Loop::Event	1908	POE 20000 349.67 12317.24 uses POE::Loop::Event
1542		1909
1543	=head3 Discussion	1910	=head3 Discussion
1544		1911
1545	This benchmark I<does> measure scalability and overall performance of the	1912	This benchmark I<does> measure scalability and overall performance of the
1546	particular event loop.	1913	particular event loop.
…		…
1548	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
1549	is relatively high, though.	1916	is relatively high, though.
1550		1917
1551	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
1552	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.
1553		1923
1554	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
1555	understand why). Callback invocation also has a high overhead compared to	1925	understand why). Callback invocation also has a high overhead compared to
1556	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
1557	uses select or poll in basically all documented configurations.	1927	uses select or poll in basically all documented configurations.
…		…
1620	=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
1621	watchers, as the management overhead dominates.	1991	watchers, as the management overhead dominates.
1622		1992
1623	=back	1993	=back
1624		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};
1625		2093
1626	=head1 FORK	2094	=head1 FORK
1627		2095
1628	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
1629	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>
…		…
1643	specified in the variable.	2111	specified in the variable.
1644		2112
1645	You can make AnyEvent completely ignore this variable by deleting it	2113	You can make AnyEvent completely ignore this variable by deleting it
1646	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:
1647		2115
1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2116	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1649		2117
1650	use AnyEvent;	2118	use AnyEvent;
1651		2119
1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2120	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1653	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
1654	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).
1655		2137
1656		2138
1657	=head1 SEE ALSO	2139	=head1 SEE ALSO
1658		2140
1659	Utility functions: L<AnyEvent::Util>.	2141	Utility functions: L<AnyEvent::Util>.
…		…
1676	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>.
1677		2159
1678		2160
1679	=head1 AUTHOR	2161	=head1 AUTHOR
1680		2162
1681	Marc Lehmann <schmorp@schmorp.de>	2163	Marc Lehmann <schmorp@schmorp.de>
1682	http://home.schmorp.de/	2164	http://home.schmorp.de/
1683		2165
1684	=cut	2166	=cut
1685		2167
1686	1	2168	1
1687		2169

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