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Revision 1.217 by root, Tue Jun 23 23:37:32 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 = 4.412;
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 $WIN32;
		945
		946	BEGIN {
		947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		949
		950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		951	if ${^TAINT};
		952	}
		953
707	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
708		955
709	our @REGISTRY;	956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
710
711	our %PROTOCOL; # (ipv4|ipv6) => (1|2)
712		957
713	{	958	{
714	my $idx;	959	my $idx;
715	$PROTOCOL{$_} = ++$idx	960	$PROTOCOL{$_} = ++$idx
		961	for reverse split /\s*,\s*/,
716	for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
717	}	963	}
718		964
719	my @models = (	965	my @models = (
720	[EV:: => AnyEvent::Impl::EV::],	966	[EV:: => AnyEvent::Impl::EV::],
721	[Event:: => AnyEvent::Impl::Event::],	967	[Event:: => AnyEvent::Impl::Event::],
722	[Tk:: => AnyEvent::Impl::Tk::],
723	[Wx:: => AnyEvent::Impl::POE::],
724	[Prima:: => AnyEvent::Impl::POE::],
725	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
726	# everything below here will not be autoprobed as the pureperl backend should work everywhere	969	# everything below here will not be autoprobed
727	[Glib:: => AnyEvent::Impl::Glib::],	970	# as the pureperl backend should work everywhere
		971	# and is usually faster
		972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
728	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
729	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
730	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		977	[Wx:: => AnyEvent::Impl::POE::],
		978	[Prima:: => AnyEvent::Impl::POE::],
731	);	979	);
732		980
733	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	981	our %method = map +($_ => 1),
		982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
734		983
735	our @post_detect;	984	our @post_detect;
736		985
737	sub post_detect(&) {	986	sub post_detect(&) {
738	my ($cb) = @_;	987	my ($cb) = @_;
…		…
743	1	992	1
744	} else {	993	} else {
745	push @post_detect, $cb;	994	push @post_detect, $cb;
746		995
747	defined wantarray	996	defined wantarray
748	? bless \$cb, "AnyEvent::Util::PostDetect"	997	? bless \$cb, "AnyEvent::Util::postdetect"
749	: ()	998	: ()
750	}	999	}
751	}	1000	}
752		1001
753	sub AnyEvent::Util::PostDetect::DESTROY {	1002	sub AnyEvent::Util::postdetect::DESTROY {
754	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
755	}	1004	}
756		1005
757	sub detect() {	1006	sub detect() {
758	unless ($MODEL) {	1007	unless ($MODEL) {
759	no strict 'refs';	1008	no strict 'refs';
		1009	local $SIG{__DIE__};
760		1010
761	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
762	my $model = "AnyEvent::Impl::$1";	1012	my $model = "AnyEvent::Impl::$1";
763	if (eval "require $model") {	1013	if (eval "require $model") {
764	$MODEL = $model;	1014	$MODEL = $model;
…		…
794	last;	1044	last;
795	}	1045	}
796	}	1046	}
797		1047
798	$MODEL	1048	$MODEL
799	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
800	}	1050	}
801	}	1051	}
802		1052
		1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1054
803	unshift @ISA, $MODEL;	1055	unshift @ISA, $MODEL;
804	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1056
		1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
805		1058
806	(shift @post_detect)->() while @post_detect;	1059	(shift @post_detect)->() while @post_detect;
807	}	1060	}
808		1061
809	$MODEL	1062	$MODEL
…		…
819		1072
820	my $class = shift;	1073	my $class = shift;
821	$class->$func (@_);	1074	$class->$func (@_);
822	}	1075	}
823		1076
		1077	# utility function to dup a filehandle. this is used by many backends
		1078	# to support binding more than one watcher per filehandle (they usually
		1079	# allow only one watcher per fd, so we dup it to get a different one).
		1080	sub _dupfh($$$$) {
		1081	my ($poll, $fh, $r, $w) = @_;
		1082
		1083	# cygwin requires the fh mode to be matching, unix doesn't
		1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1085	: $poll eq "w" ? ($w, ">")
		1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1087
		1088	open my $fh2, "$mode&" . fileno $fh
		1089	or die "cannot dup() filehandle: $!,";
		1090
		1091	# we assume CLOEXEC is already set by perl in all important cases
		1092
		1093	($fh2, $rw)
		1094	}
		1095
824	package AnyEvent::Base;	1096	package AnyEvent::Base;
825		1097
		1098	# default implementations for many methods
		1099
		1100	BEGIN {
		1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1102	*_time = \&Time::HiRes::time;
		1103	# if (eval "use POSIX (); (POSIX::times())...
		1104	} else {
		1105	*_time = sub { time }; # epic fail
		1106	}
		1107	}
		1108
		1109	sub time { _time }
		1110	sub now { _time }
		1111	sub now_update { }
		1112
826	# default implementation for ->condvar	1113	# default implementation for ->condvar
827		1114
828	sub condvar {	1115	sub condvar {
829	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
830	}	1117	}
831		1118
832	# default implementation for ->signal	1119	# default implementation for ->signal
833		1120
834	our %SIG_CB;	1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1122
		1123	sub _signal_exec {
		1124	sysread $SIGPIPE_R, my $dummy, 4;
		1125
		1126	while (%SIG_EV) {
		1127	for (keys %SIG_EV) {
		1128	delete $SIG_EV{$_};
		1129	$_->() for values %{ $SIG_CB{$_} || {} };
		1130	}
		1131	}
		1132	}
835		1133
836	sub signal {	1134	sub signal {
837	my (undef, %arg) = @_;	1135	my (undef, %arg) = @_;
838		1136
		1137	unless ($SIGPIPE_R) {
		1138	require Fcntl;
		1139
		1140	if (AnyEvent::WIN32) {
		1141	require AnyEvent::Util;
		1142
		1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1146	} else {
		1147	pipe $SIGPIPE_R, $SIGPIPE_W;
		1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154	}
		1155
		1156	$SIGPIPE_R
		1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1158
		1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1160	}
		1161
839	my $signal = uc $arg{signal}	1162	my $signal = uc $arg{signal}
840	or Carp::croak "required option 'signal' is missing";	1163	or Carp::croak "required option 'signal' is missing";
841		1164
842	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
843	$SIG{$signal} ||= sub {	1166	$SIG{$signal} ||= sub {
844	$_->() for values %{ $SIG_CB{$signal} || {} };	1167	local $!;
		1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1169	undef $SIG_EV{$signal};
845	};	1170	};
846		1171
847	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
848	}	1173	}
849		1174
850	sub AnyEvent::Base::Signal::DESTROY {	1175	sub AnyEvent::Base::signal::DESTROY {
851	my ($signal, $cb) = @{$_[0]};	1176	my ($signal, $cb) = @{$_[0]};
852		1177
853	delete $SIG_CB{$signal}{$cb};	1178	delete $SIG_CB{$signal}{$cb};
854		1179
		1180	# delete doesn't work with older perls - they then
		1181	# print weird messages, or just unconditionally exit
		1182	# instead of getting the default action.
855	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
856	}	1184	}
857		1185
858	# default implementation for ->child	1186	# default implementation for ->child
859		1187
860	our %PID_CB;	1188	our %PID_CB;
861	our $CHLD_W;	1189	our $CHLD_W;
862	our $CHLD_DELAY_W;	1190	our $CHLD_DELAY_W;
863	our $PID_IDLE;
864	our $WNOHANG;	1191	our $WNOHANG;
865		1192
866	sub _child_wait {	1193	sub _sigchld {
867	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
868	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
869	(values %{ $PID_CB{0} || {} });	1196	(values %{ $PID_CB{0} || {} });
870	}	1197	}
871
872	undef $PID_IDLE;
873	}
874
875	sub _sigchld {
876	# make sure we deliver these changes "synchronous" with the event loop.
877	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
878	undef $CHLD_DELAY_W;
879	&_child_wait;
880	});
881	}	1198	}
882		1199
883	sub child {	1200	sub child {
884	my (undef, %arg) = @_;	1201	my (undef, %arg) = @_;
885		1202
886	defined (my $pid = $arg{pid} + 0)	1203	defined (my $pid = $arg{pid} + 0)
887	or Carp::croak "required option 'pid' is missing";	1204	or Carp::croak "required option 'pid' is missing";
888		1205
889	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
890		1207
891	unless ($WNOHANG) {
892	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
893	}
894		1209
895	unless ($CHLD_W) {	1210	unless ($CHLD_W) {
896	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
897	# child could be a zombie already, so make at least one round	1212	# child could be a zombie already, so make at least one round
898	&_sigchld;	1213	&_sigchld;
899	}	1214	}
900		1215
901	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
902	}	1217	}
903		1218
904	sub AnyEvent::Base::Child::DESTROY {	1219	sub AnyEvent::Base::child::DESTROY {
905	my ($pid, $cb) = @{$_[0]};	1220	my ($pid, $cb) = @{$_[0]};
906		1221
907	delete $PID_CB{$pid}{$cb};	1222	delete $PID_CB{$pid}{$cb};
908	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
909		1224
910	undef $CHLD_W unless keys %PID_CB;	1225	undef $CHLD_W unless keys %PID_CB;
911	}	1226	}
912		1227
		1228	# idle emulation is done by simply using a timer, regardless
		1229	# of whether the process is idle or not, and not letting
		1230	# the callback use more than 50% of the time.
		1231	sub idle {
		1232	my (undef, %arg) = @_;
		1233
		1234	my ($cb, $w, $rcb) = $arg{cb};
		1235
		1236	$rcb = sub {
		1237	if ($cb) {
		1238	$w = _time;
		1239	&$cb;
		1240	$w = _time - $w;
		1241
		1242	# never use more then 50% of the time for the idle watcher,
		1243	# within some limits
		1244	$w = 0.0001 if $w < 0.0001;
		1245	$w = 5 if $w > 5;
		1246
		1247	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1248	} else {
		1249	# clean up...
		1250	undef $w;
		1251	undef $rcb;
		1252	}
		1253	};
		1254
		1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1256
		1257	bless \\$cb, "AnyEvent::Base::idle"
		1258	}
		1259
		1260	sub AnyEvent::Base::idle::DESTROY {
		1261	undef $${$_[0]};
		1262	}
		1263
913	package AnyEvent::CondVar;	1264	package AnyEvent::CondVar;
914		1265
915	our @ISA = AnyEvent::CondVar::Base::;	1266	our @ISA = AnyEvent::CondVar::Base::;
916		1267
917	package AnyEvent::CondVar::Base;	1268	package AnyEvent::CondVar::Base;
		1269
		1270	use overload
		1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1272	fallback => 1;
918		1273
919	sub _send {	1274	sub _send {
920	# nop	1275	# nop
921	}	1276	}
922		1277
…		…
963	}	1318	}
964		1319
965	# undocumented/compatibility with pre-3.4	1320	# undocumented/compatibility with pre-3.4
966	*broadcast = \&send;	1321	*broadcast = \&send;
967	*wait = \&_wait;	1322	*wait = \&_wait;
		1323
		1324	=head1 ERROR AND EXCEPTION HANDLING
		1325
		1326	In general, AnyEvent does not do any error handling - it relies on the
		1327	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1328	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1329	checking of all AnyEvent methods, however, which is highly useful during
		1330	development.
		1331
		1332	As for exception handling (i.e. runtime errors and exceptions thrown while
		1333	executing a callback), this is not only highly event-loop specific, but
		1334	also not in any way wrapped by this module, as this is the job of the main
		1335	program.
		1336
		1337	The pure perl event loop simply re-throws the exception (usually
		1338	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1340	so on.
		1341
		1342	=head1 ENVIRONMENT VARIABLES
		1343
		1344	The following environment variables are used by this module or its
		1345	submodules.
		1346
		1347	Note that AnyEvent will remove I<all> environment variables starting with
		1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1349	enabled.
		1350
		1351	=over 4
		1352
		1353	=item C<PERL_ANYEVENT_VERBOSE>
		1354
		1355	By default, AnyEvent will be completely silent except in fatal
		1356	conditions. You can set this environment variable to make AnyEvent more
		1357	talkative.
		1358
		1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1360	conditions, such as not being able to load the event model specified by
		1361	C<PERL_ANYEVENT_MODEL>.
		1362
		1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1364	model it chooses.
		1365
		1366	=item C<PERL_ANYEVENT_STRICT>
		1367
		1368	AnyEvent does not do much argument checking by default, as thorough
		1369	argument checking is very costly. Setting this variable to a true value
		1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1371	check the arguments passed to most method calls. If it finds any problems
		1372	it will croak.
		1373
		1374	In other words, enables "strict" mode.
		1375
		1376	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1378	developing programs can be very useful, however.
		1379
		1380	=item C<PERL_ANYEVENT_MODEL>
		1381
		1382	This can be used to specify the event model to be used by AnyEvent, before
		1383	auto detection and -probing kicks in. It must be a string consisting
		1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1385	and the resulting module name is loaded and if the load was successful,
		1386	used as event model. If it fails to load AnyEvent will proceed with
		1387	auto detection and -probing.
		1388
		1389	This functionality might change in future versions.
		1390
		1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1392	could start your program like this:
		1393
		1394	PERL_ANYEVENT_MODEL=Perl perl ...
		1395
		1396	=item C<PERL_ANYEVENT_PROTOCOLS>
		1397
		1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1400	of auto probing).
		1401
		1402	Must be set to a comma-separated list of protocols or address families,
		1403	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1404	used, and preference will be given to protocols mentioned earlier in the
		1405	list.
		1406
		1407	This variable can effectively be used for denial-of-service attacks
		1408	against local programs (e.g. when setuid), although the impact is likely
		1409	small, as the program has to handle conenction and other failures anyways.
		1410
		1411	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1413	- only support IPv4, never try to resolve or contact IPv6
		1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1415	IPv6, but prefer IPv6 over IPv4.
		1416
		1417	=item C<PERL_ANYEVENT_EDNS0>
		1418
		1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1420	for DNS. This extension is generally useful to reduce DNS traffic, but
		1421	some (broken) firewalls drop such DNS packets, which is why it is off by
		1422	default.
		1423
		1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1425	EDNS0 in its DNS requests.
		1426
		1427	=item C<PERL_ANYEVENT_MAX_FORKS>
		1428
		1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1430	will create in parallel.
		1431
		1432	=back
968		1433
969	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
970		1435
971	This is an advanced topic that you do not normally need to use AnyEvent in	1436	This is an advanced topic that you do not normally need to use AnyEvent in
972	a module. This section is only of use to event loop authors who want to	1437	a module. This section is only of use to event loop authors who want to
…		…
1006		1471
1007	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1472	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1008	condition variables: code blocking while waiting for a condition will	1473	condition variables: code blocking while waiting for a condition will
1009	C<die>. This still works with most modules/usages, and blocking calls must	1474	C<die>. This still works with most modules/usages, and blocking calls must
1010	not be done in an interactive application, so it makes sense.	1475	not be done in an interactive application, so it makes sense.
1011
1012	=head1 ENVIRONMENT VARIABLES
1013
1014	The following environment variables are used by this module:
1015
1016	=over 4
1017
1018	=item C<PERL_ANYEVENT_VERBOSE>
1019
1020	By default, AnyEvent will be completely silent except in fatal
1021	conditions. You can set this environment variable to make AnyEvent more
1022	talkative.
1023
1024	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1025	conditions, such as not being able to load the event model specified by
1026	C<PERL_ANYEVENT_MODEL>.
1027
1028	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1029	model it chooses.
1030
1031	=item C<PERL_ANYEVENT_MODEL>
1032
1033	This can be used to specify the event model to be used by AnyEvent, before
1034	autodetection and -probing kicks in. It must be a string consisting
1035	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1036	and the resulting module name is loaded and if the load was successful,
1037	used as event model. If it fails to load AnyEvent will proceed with
1038	autodetection and -probing.
1039
1040	This functionality might change in future versions.
1041
1042	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1043	could start your program like this:
1044
1045	PERL_ANYEVENT_MODEL=Perl perl ...
1046
1047	=item C<PERL_ANYEVENT_PROTOCOLS>
1048
1049	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1050	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1051	of autoprobing).
1052
1053	Must be set to a comma-separated list of protocols or address families,
1054	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1055	used, and preference will be given to protocols mentioned earlier in the
1056	list.
1057
1058	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1059	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1060	- only support IPv4, never try to resolve or contact IPv6
1061	addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1062	IPv6, but prefer IPv6 over IPv4.
1063
1064	=back
1065		1476
1066	=head1 EXAMPLE PROGRAM	1477	=head1 EXAMPLE PROGRAM
1067		1478
1068	The following program uses an I/O watcher to read data from STDIN, a timer	1479	The following program uses an I/O watcher to read data from STDIN, a timer
1069	to display a message once per second, and a condition variable to quit the	1480	to display a message once per second, and a condition variable to quit the
…		…
1153	syswrite $txn->{fh}, $txn->{request}	1564	syswrite $txn->{fh}, $txn->{request}
1154	or die "connection or write error";	1565	or die "connection or write error";
1155	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1566	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1156		1567
1157	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1568	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1158	result and signals any possible waiters that the request ahs finished:	1569	result and signals any possible waiters that the request has finished:
1159		1570
1160	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1571	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1161		1572
1162	if (end-of-file or data complete) {	1573	if (end-of-file or data complete) {
1163	$txn->{result} = $txn->{buf};	1574	$txn->{result} = $txn->{buf};
…		…
1171		1582
1172	$txn->{finished}->recv;	1583	$txn->{finished}->recv;
1173	return $txn->{result};	1584	return $txn->{result};
1174		1585
1175	The actual code goes further and collects all errors (C<die>s, exceptions)	1586	The actual code goes further and collects all errors (C<die>s, exceptions)
1176	that occured during request processing. The C<result> method detects	1587	that occurred during request processing. The C<result> method detects
1177	whether an exception as thrown (it is stored inside the $txn object)	1588	whether an exception as thrown (it is stored inside the $txn object)
1178	and just throws the exception, which means connection errors and other	1589	and just throws the exception, which means connection errors and other
1179	problems get reported tot he code that tries to use the result, not in a	1590	problems get reported tot he code that tries to use the result, not in a
1180	random callback.	1591	random callback.
1181		1592
…		…
1227	of various event loops I prepared some benchmarks.	1638	of various event loops I prepared some benchmarks.
1228		1639
1229	=head2 BENCHMARKING ANYEVENT OVERHEAD	1640	=head2 BENCHMARKING ANYEVENT OVERHEAD
1230		1641
1231	Here is a benchmark of various supported event models used natively and	1642	Here is a benchmark of various supported event models used natively and
1232	through anyevent. The benchmark creates a lot of timers (with a zero	1643	through AnyEvent. The benchmark creates a lot of timers (with a zero
1233	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1234	which it is), lets them fire exactly once and destroys them again.	1645	which it is), lets them fire exactly once and destroys them again.
1235		1646
1236	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1237	distribution.	1648	distribution.
…		…
1263	watcher.	1674	watcher.
1264		1675
1265	=head3 Results	1676	=head3 Results
1266		1677
1267	name watchers bytes create invoke destroy comment	1678	name watchers bytes create invoke destroy comment
1268	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1269	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1270	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1271	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1272	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1273	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1274	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1275	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1276	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1277	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1278		1689
1279	=head3 Discussion	1690	=head3 Discussion
1280		1691
1281	The benchmark does I<not> measure scalability of the event loop very	1692	The benchmark does I<not> measure scalability of the event loop very
1282	well. For example, a select-based event loop (such as the pure perl one)	1693	well. For example, a select-based event loop (such as the pure perl one)
…		…
1360		1771
1361	=back	1772	=back
1362		1773
1363	=head2 BENCHMARKING THE LARGE SERVER CASE	1774	=head2 BENCHMARKING THE LARGE SERVER CASE
1364		1775
1365	This benchmark atcually benchmarks the event loop itself. It works by	1776	This benchmark actually benchmarks the event loop itself. It works by
1366	creating a number of "servers": each server consists of a socketpair, a	1777	creating a number of "servers": each server consists of a socket pair, a
1367	timeout watcher that gets reset on activity (but never fires), and an I/O	1778	timeout watcher that gets reset on activity (but never fires), and an I/O
1368	watcher waiting for input on one side of the socket. Each time the socket	1779	watcher waiting for input on one side of the socket. Each time the socket
1369	watcher reads a byte it will write that byte to a random other "server".	1780	watcher reads a byte it will write that byte to a random other "server".
1370		1781
1371	The effect is that there will be a lot of I/O watchers, only part of which	1782	The effect is that there will be a lot of I/O watchers, only part of which
1372	are active at any one point (so there is a constant number of active	1783	are active at any one point (so there is a constant number of active
1373	fds for each loop iterstaion, but which fds these are is random). The	1784	fds for each loop iteration, but which fds these are is random). The
1374	timeout is reset each time something is read because that reflects how	1785	timeout is reset each time something is read because that reflects how
1375	most timeouts work (and puts extra pressure on the event loops).	1786	most timeouts work (and puts extra pressure on the event loops).
1376		1787
1377	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1378	(1%) are active. This mirrors the activity of large servers with many	1789	(1%) are active. This mirrors the activity of large servers with many
1379	connections, most of which are idle at any one point in time.	1790	connections, most of which are idle at any one point in time.
1380		1791
1381	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1382	distribution.	1793	distribution.
…		…
1384	=head3 Explanation of the columns	1795	=head3 Explanation of the columns
1385		1796
1386	I<sockets> is the number of sockets, and twice the number of "servers" (as	1797	I<sockets> is the number of sockets, and twice the number of "servers" (as
1387	each server has a read and write socket end).	1798	each server has a read and write socket end).
1388		1799
1389	I<create> is the time it takes to create a socketpair (which is	1800	I<create> is the time it takes to create a socket pair (which is
1390	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1801	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1391		1802
1392	I<request>, the most important value, is the time it takes to handle a	1803	I<request>, the most important value, is the time it takes to handle a
1393	single "request", that is, reading the token from the pipe and forwarding	1804	single "request", that is, reading the token from the pipe and forwarding
1394	it to another server. This includes deleting the old timeout and creating	1805	it to another server. This includes deleting the old timeout and creating
…		…
1467	speed most when you have lots of watchers, not when you only have a few of	1878	speed most when you have lots of watchers, not when you only have a few of
1468	them).	1879	them).
1469		1880
1470	EV is again fastest.	1881	EV is again fastest.
1471		1882
1472	Perl again comes second. It is noticably faster than the C-based event	1883	Perl again comes second. It is noticeably faster than the C-based event
1473	loops Event and Glib, although the difference is too small to really	1884	loops Event and Glib, although the difference is too small to really
1474	matter.	1885	matter.
1475		1886
1476	POE also performs much better in this case, but is is still far behind the	1887	POE also performs much better in this case, but is is still far behind the
1477	others.	1888	others.
…		…
1482		1893
1483	=item * C-based event loops perform very well with small number of	1894	=item * C-based event loops perform very well with small number of
1484	watchers, as the management overhead dominates.	1895	watchers, as the management overhead dominates.
1485		1896
1486	=back	1897	=back
		1898
		1899	=head2 THE IO::Lambda BENCHMARK
		1900
		1901	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1904	shouldn't come as a surprise to anybody). As such, the benchmark is
		1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very
		1906	optimal. But how would AnyEvent compare when used without the extra
		1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1908
		1909	The benchmark itself creates an echo-server, and then, for 500 times,
		1910	connects to the echo server, sends a line, waits for the reply, and then
		1911	creates the next connection. This is a rather bad benchmark, as it doesn't
		1912	test the efficiency of the framework, but it is a benchmark nevertheless.
		1913
		1914	name runtime
		1915	Lambda/select 0.330 sec
		1916	+ optimized 0.122 sec
		1917	Lambda/AnyEvent 0.327 sec
		1918	+ optimized 0.138 sec
		1919	Raw sockets/select 0.077 sec
		1920	POE/select, components 0.662 sec
		1921	POE/select, raw sockets 0.226 sec
		1922	POE/select, optimized 0.404 sec
		1923
		1924	AnyEvent/select/nb 0.085 sec
		1925	AnyEvent/EV/nb 0.068 sec
		1926	+state machine 0.134 sec
		1927
		1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda
		1929	benchmarks actually make blocking connects and use 100% blocking I/O,
		1930	defeating the purpose of an event-based solution. All of the newly
		1931	written AnyEvent benchmarks use 100% non-blocking connects (using
		1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects
		1934	generally require a lot more bookkeeping and event handling than blocking
		1935	connects (which involve a single syscall only).
		1936
		1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1938	offers similar expressive power as POE and IO::Lambda (using conventional
		1939	Perl syntax), which means both the echo server and the client are 100%
		1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.
		1941
		1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets
		1943	benchmark", while AnyEvent + its pure perl backend easily beats
		1944	IO::Lambda and POE.
		1945
		1946	And even the 100% non-blocking version written using the high-level (and
		1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,
		1948	even thought it does all of DNS, tcp-connect and socket I/O in a
		1949	non-blocking way.
		1950
		1951	The two AnyEvent benchmarks can be found as F<eg/ae0.pl> and F<eg/ae2.pl>
		1952	in the AnyEvent distribution, the remaining benchmarks are part of the
		1953	IO::lambda distribution and were used without any changes.
		1954
		1955
		1956	=head1 SIGNALS
		1957
		1958	AnyEvent currently installs handlers for these signals:
		1959
		1960	=over 4
		1961
		1962	=item SIGCHLD
		1963
		1964	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1965	emulation for event loops that do not support them natively. Also, some
		1966	event loops install a similar handler.
		1967
		1968	=item SIGPIPE
		1969
		1970	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1971	when AnyEvent gets loaded.
		1972
		1973	The rationale for this is that AnyEvent users usually do not really depend
		1974	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1975	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1976	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1977	some random socket.
		1978
		1979	The rationale for installing a no-op handler as opposed to ignoring it is
		1980	that this way, the handler will be restored to defaults on exec.
		1981
		1982	Feel free to install your own handler, or reset it to defaults.
		1983
		1984	=back
		1985
		1986	=cut
		1987
		1988	$SIG{PIPE} = sub { }
		1989	unless defined $SIG{PIPE};
1487		1990
1488		1991
1489	=head1 FORK	1992	=head1 FORK
1490		1993
1491	Most event libraries are not fork-safe. The ones who are usually are	1994	Most event libraries are not fork-safe. The ones who are usually are
…		…
1506	specified in the variable.	2009	specified in the variable.
1507		2010
1508	You can make AnyEvent completely ignore this variable by deleting it	2011	You can make AnyEvent completely ignore this variable by deleting it
1509	before the first watcher gets created, e.g. with a C<BEGIN> block:	2012	before the first watcher gets created, e.g. with a C<BEGIN> block:
1510		2013
1511	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2014	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1512		2015
1513	use AnyEvent;	2016	use AnyEvent;
1514		2017
1515	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2018	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1516	be used to probe what backend is used and gain other information (which is	2019	be used to probe what backend is used and gain other information (which is
1517	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2020	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2021	$ENV{PERL_ANYEVENT_STRICT}.
		2022
		2023
		2024	=head1 BUGS
		2025
		2026	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2027	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2028	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2029	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2030	pronounced).
1518		2031
1519		2032
1520	=head1 SEE ALSO	2033	=head1 SEE ALSO
1521		2034
1522	Utility functions: L<AnyEvent::Util>.	2035	Utility functions: L<AnyEvent::Util>.
…		…
1539	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2052	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1540		2053
1541		2054
1542	=head1 AUTHOR	2055	=head1 AUTHOR
1543		2056
1544	Marc Lehmann <schmorp@schmorp.de>	2057	Marc Lehmann <schmorp@schmorp.de>
1545	http://home.schmorp.de/	2058	http://home.schmorp.de/
1546		2059
1547	=cut	2060	=cut
1548		2061
1549	1	2062	1
1550		2063

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