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Revision 1.211 by root, Sat Jun 6 12:04:30 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 enourmous 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
113	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
114		144
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) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
242	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
246		364
247	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	366	between multiple watchers.
249		367
250	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
260		378
261	The child process is specified by the C<pid> argument (if set to C<0>, it	379	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	380	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	381	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	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	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	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	402	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		404
280	Example: fork a process and wait for it	405	Example: fork a process and wait for it
281		406
282	my $done = AnyEvent->condvar;	407	my $done = AnyEvent->condvar;
283		408
284	my $pid = fork or exit 5;	409	my $pid = fork or exit 5;
285		410
286	my $w = AnyEvent->child (	411	my $w = AnyEvent->child (
287	pid => $pid,	412	pid => $pid,
288	cb => sub {	413	cb => sub {
289	my ($pid, $status) = @_;	414	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	415	warn "pid $pid exited with status $status";
291	$done->send;	416	$done->send;
292	},	417	},
293	);	418	);
294		419
295	# do something else, then wait for process exit	420	# do something else, then wait for process exit
296	$done->recv;	421	$done->recv;
		422
		423	=head2 IDLE WATCHERS
		424
		425	Sometimes there is a need to do something, but it is not so important
		426	to do it instantly, but only when there is nothing better to do. This
		427	"nothing better to do" is usually defined to be "no other events need
		428	attention by the event loop".
		429
		430	Idle watchers ideally get invoked when the event loop has nothing
		431	better to do, just before it would block the process to wait for new
		432	events. Instead of blocking, the idle watcher is invoked.
		433
		434	Most event loops unfortunately do not really support idle watchers (only
		435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		436	will simply call the callback "from time to time".
		437
		438	Example: read lines from STDIN, but only process them when the
		439	program is otherwise idle:
		440
		441	my @lines; # read data
		442	my $idle_w;
		443	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		444	push @lines, scalar <STDIN>;
		445
		446	# start an idle watcher, if not already done
		447	$idle_w ||= AnyEvent->idle (cb => sub {
		448	# handle only one line, when there are lines left
		449	if (my $line = shift @lines) {
		450	print "handled when idle: $line";
		451	} else {
		452	# otherwise disable the idle watcher again
		453	undef $idle_w;
		454	}
		455	});
		456	});
297		457
298	=head2 CONDITION VARIABLES	458	=head2 CONDITION VARIABLES
299		459
300	If you are familiar with some event loops you will know that all of them	460	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	461	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	467	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	468	because they represent a condition that must become true.
309		469
310	Condition variables can be created by calling the C<< AnyEvent->condvar	470	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	471	>> method, usually without arguments. The only argument pair allowed is
		472
312	C<cb>, which specifies a callback to be called when the condition variable	473	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	474	becomes true, with the condition variable as the first argument (but not
		475	the results).
314		476
315	After creation, the conditon variable is "false" until it becomes "true"	477	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method.	478	by calling the C<send> method (or calling the condition variable as if it
		479	were a callback, read about the caveats in the description for the C<<
		480	->send >> method).
317		481
318	Condition variables are similar to callbacks, except that you can	482	Condition variables are similar to callbacks, except that you can
319	optionally wait for them. They can also be called merge points - points	483	optionally wait for them. They can also be called merge points - points
320	in time where multiple outstandign events have been processed. And yet	484	in time where multiple outstanding events have been processed. And yet
321	another way to call them is transations - each condition variable can be	485	another way to call them is transactions - each condition variable can be
322	used to represent a transaction, which finishes at some point and delivers	486	used to represent a transaction, which finishes at some point and delivers
323	a result.	487	a result.
324		488
325	Condition variables are very useful to signal that something has finished,	489	Condition variables are very useful to signal that something has finished,
326	for example, if you write a module that does asynchronous http requests,	490	for example, if you write a module that does asynchronous http requests,
…		…
332	you can block your main program until an event occurs - for example, you	496	you can block your main program until an event occurs - for example, you
333	could C<< ->recv >> in your main program until the user clicks the Quit	497	could C<< ->recv >> in your main program until the user clicks the Quit
334	button of your app, which would C<< ->send >> the "quit" event.	498	button of your app, which would C<< ->send >> the "quit" event.
335		499
336	Note that condition variables recurse into the event loop - if you have	500	Note that condition variables recurse into the event loop - if you have
337	two pieces of code that call C<< ->recv >> in a round-robbin fashion, you	501	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338	lose. Therefore, condition variables are good to export to your caller, but	502	lose. Therefore, condition variables are good to export to your caller, but
339	you should avoid making a blocking wait yourself, at least in callbacks,	503	you should avoid making a blocking wait yourself, at least in callbacks,
340	as this asks for trouble.	504	as this asks for trouble.
341		505
342	Condition variables are represented by hash refs in perl, and the keys	506	Condition variables are represented by hash refs in perl, and the keys
…		…
347		511
348	There are two "sides" to a condition variable - the "producer side" which	512	There are two "sides" to a condition variable - the "producer side" which
349	eventually calls C<< -> send >>, and the "consumer side", which waits	513	eventually calls C<< -> send >>, and the "consumer side", which waits
350	for the send to occur.	514	for the send to occur.
351		515
352	Example:	516	Example: wait for a timer.
353		517
354	# wait till the result is ready	518	# wait till the result is ready
355	my $result_ready = AnyEvent->condvar;	519	my $result_ready = AnyEvent->condvar;
356		520
357	# do something such as adding a timer	521	# do something such as adding a timer
…		…
365		529
366	# this "blocks" (while handling events) till the callback	530	# this "blocks" (while handling events) till the callback
367	# calls send	531	# calls send
368	$result_ready->recv;	532	$result_ready->recv;
369		533
		534	Example: wait for a timer, but take advantage of the fact that
		535	condition variables are also code references.
		536
		537	my $done = AnyEvent->condvar;
		538	my $delay = AnyEvent->timer (after => 5, cb => $done);
		539	$done->recv;
		540
		541	Example: Imagine an API that returns a condvar and doesn't support
		542	callbacks. This is how you make a synchronous call, for example from
		543	the main program:
		544
		545	use AnyEvent::CouchDB;
		546
		547	...
		548
		549	my @info = $couchdb->info->recv;
		550
		551	And this is how you would just ste a callback to be called whenever the
		552	results are available:
		553
		554	$couchdb->info->cb (sub {
		555	my @info = $_[0]->recv;
		556	});
		557
370	=head3 METHODS FOR PRODUCERS	558	=head3 METHODS FOR PRODUCERS
371		559
372	These methods should only be used by the producing side, i.e. the	560	These methods should only be used by the producing side, i.e. the
373	code/module that eventually sends the signal. Note that it is also	561	code/module that eventually sends the signal. Note that it is also
374	the producer side which creates the condvar in most cases, but it isn't	562	the producer side which creates the condvar in most cases, but it isn't
…		…
385	If a callback has been set on the condition variable, it is called	573	If a callback has been set on the condition variable, it is called
386	immediately from within send.	574	immediately from within send.
387		575
388	Any arguments passed to the C<send> call will be returned by all	576	Any arguments passed to the C<send> call will be returned by all
389	future C<< ->recv >> calls.	577	future C<< ->recv >> calls.
		578
		579	Condition variables are overloaded so one can call them directly
		580	(as a code reference). Calling them directly is the same as calling
		581	C<send>. Note, however, that many C-based event loops do not handle
		582	overloading, so as tempting as it may be, passing a condition variable
		583	instead of a callback does not work. Both the pure perl and EV loops
		584	support overloading, however, as well as all functions that use perl to
		585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		586	example).
390		587
391	=item $cv->croak ($error)	588	=item $cv->croak ($error)
392		589
393	Similar to send, but causes all call's to C<< ->recv >> to invoke	590	Similar to send, but causes all call's to C<< ->recv >> to invoke
394	C<Carp::croak> with the given error message/object/scalar.	591	C<Carp::croak> with the given error message/object/scalar.
…		…
443	doesn't execute once).	640	doesn't execute once).
444		641
445	This is the general pattern when you "fan out" into multiple subrequests:	642	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	643	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	644	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	645	C<begin> and for each subrequest you finish, call C<end>.
449		646
450	=back	647	=back
451		648
452	=head3 METHODS FOR CONSUMERS	649	=head3 METHODS FOR CONSUMERS
453		650
…		…
475	(programs might want to do that to stay interactive), so I<if you are	672	(programs might want to do that to stay interactive), so I<if you are
476	using this from a module, never require a blocking wait>, but let the	673	using this from a module, never require a blocking wait>, but let the
477	caller decide whether the call will block or not (for example, by coupling	674	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	675	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	676	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	677	while still supporting blocking waits if the caller so desires).
481		678
482	Another reason I<never> to C<< ->recv >> in a module is that you cannot	679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->recv >>'s in parallel, as that would require	680	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.	682	can supply.
…		…
498	=item $bool = $cv->ready	695	=item $bool = $cv->ready
499		696
500	Returns true when the condition is "true", i.e. whether C<send> or	697	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	698	C<croak> have been called.
502		699
503	=item $cb = $cv->cb ([new callback])	700	=item $cb = $cv->cb ($cb->($cv))
504		701
505	This is a mutator function that returns the callback set and optionally	702	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	703	replaces it before doing so.
507		704
508	The callback will be called when the condition becomes "true", i.e. when	705	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<recv> inside the callback	706	C<send> or C<croak> are called, with the only argument being the condition
510	or at any later time is guaranteed not to block.	707	variable itself. Calling C<recv> inside the callback or at any later time
		708	is guaranteed not to block.
511		709
512	=back	710	=back
513		711
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	712	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		713
…		…
601		799
602	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
603	do anything special (it does not need to be event-based) and let AnyEvent	801	do anything special (it does not need to be event-based) and let AnyEvent
604	decide which implementation to chose if some module relies on it.	802	decide which implementation to chose if some module relies on it.
605		803
606	If the main program relies on a specific event model. For example, in	804	If the main program relies on a specific event model - for example, in
607	Gtk2 programs you have to rely on the Glib module. You should load the	805	Gtk2 programs you have to rely on the Glib module - you should load the
608	event module before loading AnyEvent or any module that uses it: generally	806	event module before loading AnyEvent or any module that uses it: generally
609	speaking, you should load it as early as possible. The reason is that	807	speaking, you should load it as early as possible. The reason is that
610	modules might create watchers when they are loaded, and AnyEvent will	808	modules might create watchers when they are loaded, and AnyEvent will
611	decide on the event model to use as soon as it creates watchers, and it	809	decide on the event model to use as soon as it creates watchers, and it
612	might chose the wrong one unless you load the correct one yourself.	810	might chose the wrong one unless you load the correct one yourself.
613		811
614	You can chose to use a rather inefficient pure-perl implementation by	812	You can chose to use a pure-perl implementation by loading the
615	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616	behaviour everywhere, but letting AnyEvent chose is generally better.	814	everywhere, but letting AnyEvent chose the model is generally better.
		815
		816	=head2 MAINLOOP EMULATION
		817
		818	Sometimes (often for short test scripts, or even standalone programs who
		819	only want to use AnyEvent), you do not want to run a specific event loop.
		820
		821	In that case, you can use a condition variable like this:
		822
		823	AnyEvent->condvar->recv;
		824
		825	This has the effect of entering the event loop and looping forever.
		826
		827	Note that usually your program has some exit condition, in which case
		828	it is better to use the "traditional" approach of storing a condition
		829	variable somewhere, waiting for it, and sending it when the program should
		830	exit cleanly.
		831
617		832
618	=head1 OTHER MODULES	833	=head1 OTHER MODULES
619		834
620	The following is a non-exhaustive list of additional modules that use	835	The following is a non-exhaustive list of additional modules that use
621	AnyEvent and can therefore be mixed easily with other AnyEvent modules	836	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
627	=item L<AnyEvent::Util>	842	=item L<AnyEvent::Util>
628		843
629	Contains various utility functions that replace often-used but blocking	844	Contains various utility functions that replace often-used but blocking
630	functions such as C<inet_aton> by event-/callback-based versions.	845	functions such as C<inet_aton> by event-/callback-based versions.
631		846
632	=item L<AnyEvent::Handle>
633
634	Provide read and write buffers and manages watchers for reads and writes.
635
636	=item L<AnyEvent::Socket>	847	=item L<AnyEvent::Socket>
637		848
638	Provides various utility functions for (internet protocol) sockets,	849	Provides various utility functions for (internet protocol) sockets,
639	addresses and name resolution. Also functions to create non-blocking tcp	850	addresses and name resolution. Also functions to create non-blocking tcp
640	connections or tcp servers, with IPv6 and SRV record support and more.	851	connections or tcp servers, with IPv6 and SRV record support and more.
641		852
		853	=item L<AnyEvent::Handle>
		854
		855	Provide read and write buffers, manages watchers for reads and writes,
		856	supports raw and formatted I/O, I/O queued and fully transparent and
		857	non-blocking SSL/TLS.
		858
		859	=item L<AnyEvent::DNS>
		860
		861	Provides rich asynchronous DNS resolver capabilities.
		862
		863	=item L<AnyEvent::HTTP>
		864
		865	A simple-to-use HTTP library that is capable of making a lot of concurrent
		866	HTTP requests.
		867
642	=item L<AnyEvent::HTTPD>	868	=item L<AnyEvent::HTTPD>
643		869
644	Provides a simple web application server framework.	870	Provides a simple web application server framework.
645		871
646	=item L<AnyEvent::DNS>
647
648	Provides rich asynchronous DNS resolver capabilities.
649
650	=item L<AnyEvent::FastPing>	872	=item L<AnyEvent::FastPing>
651		873
652	The fastest ping in the west.	874	The fastest ping in the west.
653		875
		876	=item L<AnyEvent::DBI>
		877
		878	Executes L<DBI> requests asynchronously in a proxy process.
		879
		880	=item L<AnyEvent::AIO>
		881
		882	Truly asynchronous I/O, should be in the toolbox of every event
		883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		884	together.
		885
		886	=item L<AnyEvent::BDB>
		887
		888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		889	L<BDB> and AnyEvent together.
		890
		891	=item L<AnyEvent::GPSD>
		892
		893	A non-blocking interface to gpsd, a daemon delivering GPS information.
		894
		895	=item L<AnyEvent::IGS>
		896
		897	A non-blocking interface to the Internet Go Server protocol (used by
		898	L<App::IGS>).
		899
654	=item L<Net::IRC3>	900	=item L<AnyEvent::IRC>
655		901
656	AnyEvent based IRC client module family.	902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
657		903
658	=item L<Net::XMPP2>	904	=item L<Net::XMPP2>
659		905
660	AnyEvent based XMPP (Jabber protocol) module family.	906	AnyEvent based XMPP (Jabber protocol) module family.
661		907
…		…
670		916
671	=item L<Coro>	917	=item L<Coro>
672		918
673	Has special support for AnyEvent via L<Coro::AnyEvent>.	919	Has special support for AnyEvent via L<Coro::AnyEvent>.
674		920
675	=item L<AnyEvent::AIO>, L<IO::AIO>
676
677	Truly asynchronous I/O, should be in the toolbox of every event
678	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
679	together.
680
681	=item L<AnyEvent::BDB>, L<BDB>
682
683	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
684	IO::AIO and AnyEvent together.
685
686	=item L<IO::Lambda>	921	=item L<IO::Lambda>
687		922
688	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
689		924
690	=back	925	=back
…		…
692	=cut	927	=cut
693		928
694	package AnyEvent;	929	package AnyEvent;
695		930
696	no warnings;	931	no warnings;
697	use strict;	932	use strict qw(vars subs);
698		933
699	use Carp;	934	use Carp;
700		935
701	our $VERSION = '3.6';	936	our $VERSION = 4.41;
702	our $MODEL;	937	our $MODEL;
703		938
704	our $AUTOLOAD;	939	our $AUTOLOAD;
705	our @ISA;	940	our @ISA;
706		941
		942	our @REGISTRY;
		943
		944	our $WIN32;
		945
		946	BEGIN {
		947	my $win32 = ! ! ($^O =~ /mswin32/i);
		948	eval "sub WIN32(){ $win32 }";
		949	}
		950
707	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	951	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
708		952
709	our @REGISTRY;	953	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		954
		955	{
		956	my $idx;
		957	$PROTOCOL{$_} = ++$idx
		958	for reverse split /\s*,\s*/,
		959	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		960	}
710		961
711	my @models = (	962	my @models = (
712	[EV:: => AnyEvent::Impl::EV::],	963	[EV:: => AnyEvent::Impl::EV::],
713	[Event:: => AnyEvent::Impl::Event::],	964	[Event:: => AnyEvent::Impl::Event::],
714	[Tk:: => AnyEvent::Impl::Tk::],
715	[Wx:: => AnyEvent::Impl::POE::],
716	[Prima:: => AnyEvent::Impl::POE::],
717	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	965	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
718	# everything below here will not be autoprobed as the pureperl backend should work everywhere	966	# everything below here will not be autoprobed
719	[Glib:: => AnyEvent::Impl::Glib::],	967	# as the pureperl backend should work everywhere
		968	# and is usually faster
		969	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		970	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
720	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	971	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
721	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	972	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
722	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	973	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		974	[Wx:: => AnyEvent::Impl::POE::],
		975	[Prima:: => AnyEvent::Impl::POE::],
723	);	976	);
724		977
725	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	978	our %method = map +($_ => 1),
		979	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
726		980
727	our @post_detect;	981	our @post_detect;
728		982
729	sub post_detect(&) {	983	sub post_detect(&) {
730	my ($cb) = @_;	984	my ($cb) = @_;
…		…
735	1	989	1
736	} else {	990	} else {
737	push @post_detect, $cb;	991	push @post_detect, $cb;
738		992
739	defined wantarray	993	defined wantarray
740	? bless \$cb, "AnyEvent::Util::PostDetect"	994	? bless \$cb, "AnyEvent::Util::postdetect"
741	: ()	995	: ()
742	}	996	}
743	}	997	}
744		998
745	sub AnyEvent::Util::PostDetect::DESTROY {	999	sub AnyEvent::Util::postdetect::DESTROY {
746	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1000	@post_detect = grep $_ != ${$_[0]}, @post_detect;
747	}	1001	}
748		1002
749	sub detect() {	1003	sub detect() {
750	unless ($MODEL) {	1004	unless ($MODEL) {
751	no strict 'refs';	1005	no strict 'refs';
		1006	local $SIG{__DIE__};
752		1007
753	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1008	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
754	my $model = "AnyEvent::Impl::$1";	1009	my $model = "AnyEvent::Impl::$1";
755	if (eval "require $model") {	1010	if (eval "require $model") {
756	$MODEL = $model;	1011	$MODEL = $model;
…		…
786	last;	1041	last;
787	}	1042	}
788	}	1043	}
789		1044
790	$MODEL	1045	$MODEL
791	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1046	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
792	}	1047	}
793	}	1048	}
794		1049
		1050	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1051
795	unshift @ISA, $MODEL;	1052	unshift @ISA, $MODEL;
796	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1053
		1054	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
797		1055
798	(shift @post_detect)->() while @post_detect;	1056	(shift @post_detect)->() while @post_detect;
799	}	1057	}
800		1058
801	$MODEL	1059	$MODEL
…		…
811		1069
812	my $class = shift;	1070	my $class = shift;
813	$class->$func (@_);	1071	$class->$func (@_);
814	}	1072	}
815		1073
		1074	# utility function to dup a filehandle. this is used by many backends
		1075	# to support binding more than one watcher per filehandle (they usually
		1076	# allow only one watcher per fd, so we dup it to get a different one).
		1077	sub _dupfh($$$$) {
		1078	my ($poll, $fh, $r, $w) = @_;
		1079
		1080	# cygwin requires the fh mode to be matching, unix doesn't
		1081	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1082	: $poll eq "w" ? ($w, ">")
		1083	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1084
		1085	open my $fh2, "$mode&" . fileno $fh
		1086	or die "cannot dup() filehandle: $!,";
		1087
		1088	# we assume CLOEXEC is already set by perl in all important cases
		1089
		1090	($fh2, $rw)
		1091	}
		1092
816	package AnyEvent::Base;	1093	package AnyEvent::Base;
817		1094
		1095	# default implementations for many methods
		1096
		1097	BEGIN {
		1098	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1099	*_time = \&Time::HiRes::time;
		1100	# if (eval "use POSIX (); (POSIX::times())...
		1101	} else {
		1102	*_time = sub { time }; # epic fail
		1103	}
		1104	}
		1105
		1106	sub time { _time }
		1107	sub now { _time }
		1108	sub now_update { }
		1109
818	# default implementation for ->condvar	1110	# default implementation for ->condvar
819		1111
820	sub condvar {	1112	sub condvar {
821	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1113	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
822	}	1114	}
823		1115
824	# default implementation for ->signal	1116	# default implementation for ->signal
825		1117
826	our %SIG_CB;	1118	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1119
		1120	sub _signal_exec {
		1121	sysread $SIGPIPE_R, my $dummy, 4;
		1122
		1123	while (%SIG_EV) {
		1124	for (keys %SIG_EV) {
		1125	delete $SIG_EV{$_};
		1126	$_->() for values %{ $SIG_CB{$_} || {} };
		1127	}
		1128	}
		1129	}
827		1130
828	sub signal {	1131	sub signal {
829	my (undef, %arg) = @_;	1132	my (undef, %arg) = @_;
830		1133
		1134	unless ($SIGPIPE_R) {
		1135	require Fcntl;
		1136
		1137	if (AnyEvent::WIN32) {
		1138	require AnyEvent::Util;
		1139
		1140	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1141	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1142	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1143	} else {
		1144	pipe $SIGPIPE_R, $SIGPIPE_W;
		1145	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1146	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1147
		1148	# not strictly required, as $^F is normally 2, but let's make sure...
		1149	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1150	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1151	}
		1152
		1153	$SIGPIPE_R
		1154	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1155
		1156	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1157	}
		1158
831	my $signal = uc $arg{signal}	1159	my $signal = uc $arg{signal}
832	or Carp::croak "required option 'signal' is missing";	1160	or Carp::croak "required option 'signal' is missing";
833		1161
834	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1162	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
835	$SIG{$signal} ||= sub {	1163	$SIG{$signal} ||= sub {
836	$_->() for values %{ $SIG_CB{$signal} || {} };	1164	local $!;
		1165	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1166	undef $SIG_EV{$signal};
837	};	1167	};
838		1168
839	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1169	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
840	}	1170	}
841		1171
842	sub AnyEvent::Base::Signal::DESTROY {	1172	sub AnyEvent::Base::signal::DESTROY {
843	my ($signal, $cb) = @{$_[0]};	1173	my ($signal, $cb) = @{$_[0]};
844		1174
845	delete $SIG_CB{$signal}{$cb};	1175	delete $SIG_CB{$signal}{$cb};
846		1176
		1177	# delete doesn't work with older perls - they then
		1178	# print weird messages, or just unconditionally exit
		1179	# instead of getting the default action.
847	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1180	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
848	}	1181	}
849		1182
850	# default implementation for ->child	1183	# default implementation for ->child
851		1184
852	our %PID_CB;	1185	our %PID_CB;
853	our $CHLD_W;	1186	our $CHLD_W;
854	our $CHLD_DELAY_W;	1187	our $CHLD_DELAY_W;
855	our $PID_IDLE;
856	our $WNOHANG;	1188	our $WNOHANG;
857		1189
858	sub _child_wait {	1190	sub _sigchld {
859	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1191	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
860	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1192	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
861	(values %{ $PID_CB{0} || {} });	1193	(values %{ $PID_CB{0} || {} });
862	}	1194	}
863
864	undef $PID_IDLE;
865	}
866
867	sub _sigchld {
868	# make sure we deliver these changes "synchronous" with the event loop.
869	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
870	undef $CHLD_DELAY_W;
871	&_child_wait;
872	});
873	}	1195	}
874		1196
875	sub child {	1197	sub child {
876	my (undef, %arg) = @_;	1198	my (undef, %arg) = @_;
877		1199
878	defined (my $pid = $arg{pid} + 0)	1200	defined (my $pid = $arg{pid} + 0)
879	or Carp::croak "required option 'pid' is missing";	1201	or Carp::croak "required option 'pid' is missing";
880		1202
881	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1203	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
882		1204
883	unless ($WNOHANG) {
884	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1205	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
885	}
886		1206
887	unless ($CHLD_W) {	1207	unless ($CHLD_W) {
888	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1208	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
889	# child could be a zombie already, so make at least one round	1209	# child could be a zombie already, so make at least one round
890	&_sigchld;	1210	&_sigchld;
891	}	1211	}
892		1212
893	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1213	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
894	}	1214	}
895		1215
896	sub AnyEvent::Base::Child::DESTROY {	1216	sub AnyEvent::Base::child::DESTROY {
897	my ($pid, $cb) = @{$_[0]};	1217	my ($pid, $cb) = @{$_[0]};
898		1218
899	delete $PID_CB{$pid}{$cb};	1219	delete $PID_CB{$pid}{$cb};
900	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1220	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
901		1221
902	undef $CHLD_W unless keys %PID_CB;	1222	undef $CHLD_W unless keys %PID_CB;
903	}	1223	}
904		1224
		1225	# idle emulation is done by simply using a timer, regardless
		1226	# of whether the process is idle or not, and not letting
		1227	# the callback use more than 50% of the time.
		1228	sub idle {
		1229	my (undef, %arg) = @_;
		1230
		1231	my ($cb, $w, $rcb) = $arg{cb};
		1232
		1233	$rcb = sub {
		1234	if ($cb) {
		1235	$w = _time;
		1236	&$cb;
		1237	$w = _time - $w;
		1238
		1239	# never use more then 50% of the time for the idle watcher,
		1240	# within some limits
		1241	$w = 0.0001 if $w < 0.0001;
		1242	$w = 5 if $w > 5;
		1243
		1244	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1245	} else {
		1246	# clean up...
		1247	undef $w;
		1248	undef $rcb;
		1249	}
		1250	};
		1251
		1252	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1253
		1254	bless \\$cb, "AnyEvent::Base::idle"
		1255	}
		1256
		1257	sub AnyEvent::Base::idle::DESTROY {
		1258	undef $${$_[0]};
		1259	}
		1260
905	package AnyEvent::CondVar;	1261	package AnyEvent::CondVar;
906		1262
907	our @ISA = AnyEvent::CondVar::Base::;	1263	our @ISA = AnyEvent::CondVar::Base::;
908		1264
909	package AnyEvent::CondVar::Base;	1265	package AnyEvent::CondVar::Base;
		1266
		1267	use overload
		1268	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1269	fallback => 1;
910		1270
911	sub _send {	1271	sub _send {
912	# nop	1272	# nop
913	}	1273	}
914		1274
…		…
955	}	1315	}
956		1316
957	# undocumented/compatibility with pre-3.4	1317	# undocumented/compatibility with pre-3.4
958	*broadcast = \&send;	1318	*broadcast = \&send;
959	*wait = \&_wait;	1319	*wait = \&_wait;
		1320
		1321	=head1 ERROR AND EXCEPTION HANDLING
		1322
		1323	In general, AnyEvent does not do any error handling - it relies on the
		1324	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1325	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1326	checking of all AnyEvent methods, however, which is highly useful during
		1327	development.
		1328
		1329	As for exception handling (i.e. runtime errors and exceptions thrown while
		1330	executing a callback), this is not only highly event-loop specific, but
		1331	also not in any way wrapped by this module, as this is the job of the main
		1332	program.
		1333
		1334	The pure perl event loop simply re-throws the exception (usually
		1335	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1336	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1337	so on.
		1338
		1339	=head1 ENVIRONMENT VARIABLES
		1340
		1341	The following environment variables are used by this module or its
		1342	submodules:
		1343
		1344	=over 4
		1345
		1346	=item C<PERL_ANYEVENT_VERBOSE>
		1347
		1348	By default, AnyEvent will be completely silent except in fatal
		1349	conditions. You can set this environment variable to make AnyEvent more
		1350	talkative.
		1351
		1352	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1353	conditions, such as not being able to load the event model specified by
		1354	C<PERL_ANYEVENT_MODEL>.
		1355
		1356	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1357	model it chooses.
		1358
		1359	=item C<PERL_ANYEVENT_STRICT>
		1360
		1361	AnyEvent does not do much argument checking by default, as thorough
		1362	argument checking is very costly. Setting this variable to a true value
		1363	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1364	check the arguments passed to most method calls. If it finds any problems
		1365	it will croak.
		1366
		1367	In other words, enables "strict" mode.
		1368
		1369	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1370	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1371	developing programs can be very useful, however.
		1372
		1373	=item C<PERL_ANYEVENT_MODEL>
		1374
		1375	This can be used to specify the event model to be used by AnyEvent, before
		1376	auto detection and -probing kicks in. It must be a string consisting
		1377	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1378	and the resulting module name is loaded and if the load was successful,
		1379	used as event model. If it fails to load AnyEvent will proceed with
		1380	auto detection and -probing.
		1381
		1382	This functionality might change in future versions.
		1383
		1384	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1385	could start your program like this:
		1386
		1387	PERL_ANYEVENT_MODEL=Perl perl ...
		1388
		1389	=item C<PERL_ANYEVENT_PROTOCOLS>
		1390
		1391	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1392	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1393	of auto probing).
		1394
		1395	Must be set to a comma-separated list of protocols or address families,
		1396	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1397	used, and preference will be given to protocols mentioned earlier in the
		1398	list.
		1399
		1400	This variable can effectively be used for denial-of-service attacks
		1401	against local programs (e.g. when setuid), although the impact is likely
		1402	small, as the program has to handle conenction and other failures anyways.
		1403
		1404	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1405	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1406	- only support IPv4, never try to resolve or contact IPv6
		1407	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1408	IPv6, but prefer IPv6 over IPv4.
		1409
		1410	=item C<PERL_ANYEVENT_EDNS0>
		1411
		1412	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1413	for DNS. This extension is generally useful to reduce DNS traffic, but
		1414	some (broken) firewalls drop such DNS packets, which is why it is off by
		1415	default.
		1416
		1417	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1418	EDNS0 in its DNS requests.
		1419
		1420	=item C<PERL_ANYEVENT_MAX_FORKS>
		1421
		1422	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1423	will create in parallel.
		1424
		1425	=back
960		1426
961	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1427	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
962		1428
963	This is an advanced topic that you do not normally need to use AnyEvent in	1429	This is an advanced topic that you do not normally need to use AnyEvent in
964	a module. This section is only of use to event loop authors who want to	1430	a module. This section is only of use to event loop authors who want to
…		…
998		1464
999	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1465	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1000	condition variables: code blocking while waiting for a condition will	1466	condition variables: code blocking while waiting for a condition will
1001	C<die>. This still works with most modules/usages, and blocking calls must	1467	C<die>. This still works with most modules/usages, and blocking calls must
1002	not be done in an interactive application, so it makes sense.	1468	not be done in an interactive application, so it makes sense.
1003
1004	=head1 ENVIRONMENT VARIABLES
1005
1006	The following environment variables are used by this module:
1007
1008	=over 4
1009
1010	=item C<PERL_ANYEVENT_VERBOSE>
1011
1012	By default, AnyEvent will be completely silent except in fatal
1013	conditions. You can set this environment variable to make AnyEvent more
1014	talkative.
1015
1016	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1017	conditions, such as not being able to load the event model specified by
1018	C<PERL_ANYEVENT_MODEL>.
1019
1020	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1021	model it chooses.
1022
1023	=item C<PERL_ANYEVENT_MODEL>
1024
1025	This can be used to specify the event model to be used by AnyEvent, before
1026	autodetection and -probing kicks in. It must be a string consisting
1027	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1028	and the resulting module name is loaded and if the load was successful,
1029	used as event model. If it fails to load AnyEvent will proceed with
1030	autodetection and -probing.
1031
1032	This functionality might change in future versions.
1033
1034	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1035	could start your program like this:
1036
1037	PERL_ANYEVENT_MODEL=Perl perl ...
1038
1039	=item C<PERL_ANYEVENT_PROTOCOLS>
1040
1041	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1042	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1043	of autoprobing).
1044
1045	Must be set to a comma-separated list of protocols or address families,
1046	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1047	used, and preference will be given to protocols mentioned earlier in the
1048	list.
1049
1050	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1051	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1052	- only support IPv4, never try to resolve or contact IPv6
1053	addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1054	IPv6, but prefer IPv6 over IPv4.
1055
1056	=back
1057		1469
1058	=head1 EXAMPLE PROGRAM	1470	=head1 EXAMPLE PROGRAM
1059		1471
1060	The following program uses an I/O watcher to read data from STDIN, a timer	1472	The following program uses an I/O watcher to read data from STDIN, a timer
1061	to display a message once per second, and a condition variable to quit the	1473	to display a message once per second, and a condition variable to quit the
…		…
1145	syswrite $txn->{fh}, $txn->{request}	1557	syswrite $txn->{fh}, $txn->{request}
1146	or die "connection or write error";	1558	or die "connection or write error";
1147	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1559	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1148		1560
1149	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1561	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1150	result and signals any possible waiters that the request ahs finished:	1562	result and signals any possible waiters that the request has finished:
1151		1563
1152	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1564	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1153		1565
1154	if (end-of-file or data complete) {	1566	if (end-of-file or data complete) {
1155	$txn->{result} = $txn->{buf};	1567	$txn->{result} = $txn->{buf};
…		…
1163		1575
1164	$txn->{finished}->recv;	1576	$txn->{finished}->recv;
1165	return $txn->{result};	1577	return $txn->{result};
1166		1578
1167	The actual code goes further and collects all errors (C<die>s, exceptions)	1579	The actual code goes further and collects all errors (C<die>s, exceptions)
1168	that occured during request processing. The C<result> method detects	1580	that occurred during request processing. The C<result> method detects
1169	whether an exception as thrown (it is stored inside the $txn object)	1581	whether an exception as thrown (it is stored inside the $txn object)
1170	and just throws the exception, which means connection errors and other	1582	and just throws the exception, which means connection errors and other
1171	problems get reported tot he code that tries to use the result, not in a	1583	problems get reported tot he code that tries to use the result, not in a
1172	random callback.	1584	random callback.
1173		1585
…		…
1219	of various event loops I prepared some benchmarks.	1631	of various event loops I prepared some benchmarks.
1220		1632
1221	=head2 BENCHMARKING ANYEVENT OVERHEAD	1633	=head2 BENCHMARKING ANYEVENT OVERHEAD
1222		1634
1223	Here is a benchmark of various supported event models used natively and	1635	Here is a benchmark of various supported event models used natively and
1224	through anyevent. The benchmark creates a lot of timers (with a zero	1636	through AnyEvent. The benchmark creates a lot of timers (with a zero
1225	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1637	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1226	which it is), lets them fire exactly once and destroys them again.	1638	which it is), lets them fire exactly once and destroys them again.
1227		1639
1228	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1640	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1229	distribution.	1641	distribution.
…		…
1255	watcher.	1667	watcher.
1256		1668
1257	=head3 Results	1669	=head3 Results
1258		1670
1259	name watchers bytes create invoke destroy comment	1671	name watchers bytes create invoke destroy comment
1260	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1672	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1261	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1673	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1262	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1674	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1263	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1675	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1264	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1676	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1265	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1677	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1266	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1678	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1267	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1679	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1268	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1680	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1269	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1681	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1270		1682
1271	=head3 Discussion	1683	=head3 Discussion
1272		1684
1273	The benchmark does I<not> measure scalability of the event loop very	1685	The benchmark does I<not> measure scalability of the event loop very
1274	well. For example, a select-based event loop (such as the pure perl one)	1686	well. For example, a select-based event loop (such as the pure perl one)
…		…
1352		1764
1353	=back	1765	=back
1354		1766
1355	=head2 BENCHMARKING THE LARGE SERVER CASE	1767	=head2 BENCHMARKING THE LARGE SERVER CASE
1356		1768
1357	This benchmark atcually benchmarks the event loop itself. It works by	1769	This benchmark actually benchmarks the event loop itself. It works by
1358	creating a number of "servers": each server consists of a socketpair, a	1770	creating a number of "servers": each server consists of a socket pair, a
1359	timeout watcher that gets reset on activity (but never fires), and an I/O	1771	timeout watcher that gets reset on activity (but never fires), and an I/O
1360	watcher waiting for input on one side of the socket. Each time the socket	1772	watcher waiting for input on one side of the socket. Each time the socket
1361	watcher reads a byte it will write that byte to a random other "server".	1773	watcher reads a byte it will write that byte to a random other "server".
1362		1774
1363	The effect is that there will be a lot of I/O watchers, only part of which	1775	The effect is that there will be a lot of I/O watchers, only part of which
1364	are active at any one point (so there is a constant number of active	1776	are active at any one point (so there is a constant number of active
1365	fds for each loop iterstaion, but which fds these are is random). The	1777	fds for each loop iteration, but which fds these are is random). The
1366	timeout is reset each time something is read because that reflects how	1778	timeout is reset each time something is read because that reflects how
1367	most timeouts work (and puts extra pressure on the event loops).	1779	most timeouts work (and puts extra pressure on the event loops).
1368		1780
1369	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1781	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1370	(1%) are active. This mirrors the activity of large servers with many	1782	(1%) are active. This mirrors the activity of large servers with many
1371	connections, most of which are idle at any one point in time.	1783	connections, most of which are idle at any one point in time.
1372		1784
1373	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1785	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1374	distribution.	1786	distribution.
…		…
1376	=head3 Explanation of the columns	1788	=head3 Explanation of the columns
1377		1789
1378	I<sockets> is the number of sockets, and twice the number of "servers" (as	1790	I<sockets> is the number of sockets, and twice the number of "servers" (as
1379	each server has a read and write socket end).	1791	each server has a read and write socket end).
1380		1792
1381	I<create> is the time it takes to create a socketpair (which is	1793	I<create> is the time it takes to create a socket pair (which is
1382	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1794	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1383		1795
1384	I<request>, the most important value, is the time it takes to handle a	1796	I<request>, the most important value, is the time it takes to handle a
1385	single "request", that is, reading the token from the pipe and forwarding	1797	single "request", that is, reading the token from the pipe and forwarding
1386	it to another server. This includes deleting the old timeout and creating	1798	it to another server. This includes deleting the old timeout and creating
…		…
1459	speed most when you have lots of watchers, not when you only have a few of	1871	speed most when you have lots of watchers, not when you only have a few of
1460	them).	1872	them).
1461		1873
1462	EV is again fastest.	1874	EV is again fastest.
1463		1875
1464	Perl again comes second. It is noticably faster than the C-based event	1876	Perl again comes second. It is noticeably faster than the C-based event
1465	loops Event and Glib, although the difference is too small to really	1877	loops Event and Glib, although the difference is too small to really
1466	matter.	1878	matter.
1467		1879
1468	POE also performs much better in this case, but is is still far behind the	1880	POE also performs much better in this case, but is is still far behind the
1469	others.	1881	others.
…		…
1474		1886
1475	=item * C-based event loops perform very well with small number of	1887	=item * C-based event loops perform very well with small number of
1476	watchers, as the management overhead dominates.	1888	watchers, as the management overhead dominates.
1477		1889
1478	=back	1890	=back
		1891
		1892
		1893	=head1 SIGNALS
		1894
		1895	AnyEvent currently installs handlers for these signals:
		1896
		1897	=over 4
		1898
		1899	=item SIGCHLD
		1900
		1901	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1902	emulation for event loops that do not support them natively. Also, some
		1903	event loops install a similar handler.
		1904
		1905	=item SIGPIPE
		1906
		1907	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1908	when AnyEvent gets loaded.
		1909
		1910	The rationale for this is that AnyEvent users usually do not really depend
		1911	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1912	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1913	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1914	some random socket.
		1915
		1916	The rationale for installing a no-op handler as opposed to ignoring it is
		1917	that this way, the handler will be restored to defaults on exec.
		1918
		1919	Feel free to install your own handler, or reset it to defaults.
		1920
		1921	=back
		1922
		1923	=cut
		1924
		1925	$SIG{PIPE} = sub { }
		1926	unless defined $SIG{PIPE};
1479		1927
1480		1928
1481	=head1 FORK	1929	=head1 FORK
1482		1930
1483	Most event libraries are not fork-safe. The ones who are usually are	1931	Most event libraries are not fork-safe. The ones who are usually are
…		…
1498	specified in the variable.	1946	specified in the variable.
1499		1947
1500	You can make AnyEvent completely ignore this variable by deleting it	1948	You can make AnyEvent completely ignore this variable by deleting it
1501	before the first watcher gets created, e.g. with a C<BEGIN> block:	1949	before the first watcher gets created, e.g. with a C<BEGIN> block:
1502		1950
1503	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1951	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1504		1952
1505	use AnyEvent;	1953	use AnyEvent;
1506		1954
1507	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1955	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1508	be used to probe what backend is used and gain other information (which is	1956	be used to probe what backend is used and gain other information (which is
1509	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1957	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1958	$ENV{PERL_ANYEGENT_STRICT}.
		1959
		1960
		1961	=head1 BUGS
		1962
		1963	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1964	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1965	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1966	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1967	pronounced).
1510		1968
1511		1969
1512	=head1 SEE ALSO	1970	=head1 SEE ALSO
1513		1971
1514	Utility functions: L<AnyEvent::Util>.	1972	Utility functions: L<AnyEvent::Util>.
…		…
1531	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	1989	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1532		1990
1533		1991
1534	=head1 AUTHOR	1992	=head1 AUTHOR
1535		1993
1536	Marc Lehmann <schmorp@schmorp.de>	1994	Marc Lehmann <schmorp@schmorp.de>
1537	http://home.schmorp.de/	1995	http://home.schmorp.de/
1538		1996
1539	=cut	1997	=cut
1540		1998
1541	1	1999	1
1542		2000

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