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Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs.
Revision 1.232 by root, Thu Jul 9 01:08:22 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
124	is in control).	148	is in control).
125		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
126	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	158	to it).
129		159
130	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
134		164
135	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
136		166
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
139	undef $w;	169	undef $w;
140	});	170	});
141		171
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
144	declared.	174	declared.
145		175
146	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
147		177
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
150		180
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (or a naked 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
152	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
154	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		192
157	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
160		196
…		…
164		200
165	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
167	handles.	203	handles.
168		204
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	210	warn "read: $input\n";
175	undef $w;	211	undef $w;
176	});	212	});
…		…
186		222
187	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
190		226
191	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
192	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
193	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.
194		232
195	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.
196		236
197	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	240	warn "timeout\n";
200	});	241	});
201		242
202	# to cancel the timer:	243	# to cancel the timer:
203	undef $w;	244	undef $w;
204		245
205	Example 2:
206
207	# 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.
208	my $w;
209		247
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
213	};	250	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		251
218	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
219		253
220	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
221	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
…		…
233	timers.	267	timers.
234		268
235	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
236	AnyEvent API.	270	AnyEvent API.
237		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
238	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
239		351
240	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
241	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
242	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
243		355
244	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
245	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
246	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
247		359
…		…
263	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
264		376
265	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.
266		378
267	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
268	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
269	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
270	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
271	and exit status (as returned by waitpid), so unlike other watcher types,	383
272	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).
273		392
274	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
275	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
276	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
277		396
278	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
279	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
280	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
281		403
282	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
283	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
284	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
285		408
286	Example: fork a process and wait for it	409	Example: fork a process and wait for it
287		410
288	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
289		412
290	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
291		414
292	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
293	pid => $pid,	416	pid => $pid,
294	cb => sub {	417	cb => sub {
295	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
296	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
297	$done->send;	420	$done->send;
298	},	421	},
299	);	422	);
300		423
301	# do something else, then wait for process exit	424	# do something else, then wait for process exit
302	$done->recv;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
303		461
304	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
305		463
306	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
307	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
…		…
313	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
314	because they represent a condition that must become true.	472	because they represent a condition that must become true.
315		473
316	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
317	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
318	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
319	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
320		480
321	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
322	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
323	were a callback, read about the caveats in the description for the C<<	483	were a callback, read about the caveats in the description for the C<<
324	->send >> method).	484	->send >> method).
…		…
380		540
381	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
382	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
383	$done->recv;	543	$done->recv;
384		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
385	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
386		563
387	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
388	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
389	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
422		599
423	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
424		601
425	=item $cv->end	602	=item $cv->end
426		603
427	These two methods are EXPERIMENTAL and MIGHT CHANGE.
428
429	These two methods can be used to combine many transactions/events into	604	These two methods can be used to combine many transactions/events into
430	one. For example, a function that pings many hosts in parallel might want	605	one. For example, a function that pings many hosts in parallel might want
431	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
432		607
433	Every call to C<< ->begin >> will increment a counter, and every call to	608	Every call to C<< ->begin >> will increment a counter, and every call to
434	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
435	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
436	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
437	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
438		613
439	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
440		645
441	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
442		647
443	my %result;	648	my %result;
444	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
464	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
465	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
466	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
467	doesn't execute once).	672	doesn't execute once).
468		673
469	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
470	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
471	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
472	C<begin> and for each subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
473		679
474	=back	680	=back
475		681
476	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
477		683
…		…
522	=item $bool = $cv->ready	728	=item $bool = $cv->ready
523		729
524	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
525	C<croak> have been called.	731	C<croak> have been called.
526		732
527	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
528		734
529	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
530	replaces it before doing so.	736	replaces it before doing so.
531		737
532	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
533	C<send> or C<croak> are called. Calling C<recv> inside the callback	739	C<send> or C<croak> are called, with the only argument being the condition
534	or at any later time is guaranteed not to block.	740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
		742
		743	=back
		744
		745	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		746
		747	The available backend classes are (every class has its own manpage):
		748
		749	=over 4
		750
		751	=item Backends that are autoprobed when no other event loop can be found.
		752
		753	EV is the preferred backend when no other event loop seems to be in
		754	use. If EV is not installed, then AnyEvent will try Event, and, failing
		755	that, will fall back to its own pure-perl implementation, which is
		756	available everywhere as it comes with AnyEvent itself.
		757
		758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		761
		762	=item Backends that are transparently being picked up when they are used.
		763
		764	These will be used when they are currently loaded when the first watcher
		765	is created, in which case it is assumed that the application is using
		766	them. This means that AnyEvent will automatically pick the right backend
		767	when the main program loads an event module before anything starts to
		768	create watchers. Nothing special needs to be done by the main program.
		769
		770	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		771	AnyEvent::Impl::Tk based on Tk, very broken.
		772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		773	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		774
		775	=item Backends with special needs.
		776
		777	Qt requires the Qt::Application to be instantiated first, but will
		778	otherwise be picked up automatically. As long as the main program
		779	instantiates the application before any AnyEvent watchers are created,
		780	everything should just work.
		781
		782	AnyEvent::Impl::Qt based on Qt.
		783
		784	Support for IO::Async can only be partial, as it is too broken and
		785	architecturally limited to even support the AnyEvent API. It also
		786	is the only event loop that needs the loop to be set explicitly, so
		787	it can only be used by a main program knowing about AnyEvent. See
		788	L<AnyEvent::Impl::Async> for the gory details.
		789
		790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		791
		792	=item Event loops that are indirectly supported via other backends.
		793
		794	Some event loops can be supported via other modules:
		795
		796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		797
		798	B<WxWidgets> has no support for watching file handles. However, you can
		799	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		800	polls 20 times per second, which was considered to be too horrible to even
		801	consider for AnyEvent.
		802
		803	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		804	backend, so it can be supported through POE.
		805
		806	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		807	load L<POE> when detecting them, in the hope that POE will pick them up,
		808	in which case everything will be automatic.
535		809
536	=back	810	=back
537		811
538	=head1 GLOBAL VARIABLES AND FUNCTIONS	812	=head1 GLOBAL VARIABLES AND FUNCTIONS
539		813
…		…
544	Contains C<undef> until the first watcher is being created. Then it	818	Contains C<undef> until the first watcher is being created. Then it
545	contains the event model that is being used, which is the name of the	819	contains the event model that is being used, which is the name of the
546	Perl class implementing the model. This class is usually one of the	820	Perl class implementing the model. This class is usually one of the
547	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	821	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
548	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	822	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
549
550	The known classes so far are:
551
552	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
553	AnyEvent::Impl::Event based on Event, second best choice.
554	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
555	AnyEvent::Impl::Glib based on Glib, third-best choice.
556	AnyEvent::Impl::Tk based on Tk, very bad choice.
557	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
558	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
559	AnyEvent::Impl::POE based on POE, not generic enough for full support.
560
561	There is no support for WxWidgets, as WxWidgets has no support for
562	watching file handles. However, you can use WxWidgets through the
563	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
564	second, which was considered to be too horrible to even consider for
565	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
566	it's adaptor.
567
568	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
569	autodetecting them.
570		823
571	=item AnyEvent::detect	824	=item AnyEvent::detect
572		825
573	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	826	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
574	if necessary. You should only call this function right before you would	827	if necessary. You should only call this function right before you would
…		…
657		910
658		911
659	=head1 OTHER MODULES	912	=head1 OTHER MODULES
660		913
661	The following is a non-exhaustive list of additional modules that use	914	The following is a non-exhaustive list of additional modules that use
662	AnyEvent and can therefore be mixed easily with other AnyEvent modules	915	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
663	in the same program. Some of the modules come with AnyEvent, some are	916	modules and other event loops in the same program. Some of the modules
664	available via CPAN.	917	come with AnyEvent, most are available via CPAN.
665		918
666	=over 4	919	=over 4
667		920
668	=item L<AnyEvent::Util>	921	=item L<AnyEvent::Util>
669		922
670	Contains various utility functions that replace often-used but blocking	923	Contains various utility functions that replace often-used but blocking
671	functions such as C<inet_aton> by event-/callback-based versions.	924	functions such as C<inet_aton> by event-/callback-based versions.
672
673	=item L<AnyEvent::Handle>
674
675	Provide read and write buffers and manages watchers for reads and writes.
676		925
677	=item L<AnyEvent::Socket>	926	=item L<AnyEvent::Socket>
678		927
679	Provides various utility functions for (internet protocol) sockets,	928	Provides various utility functions for (internet protocol) sockets,
680	addresses and name resolution. Also functions to create non-blocking tcp	929	addresses and name resolution. Also functions to create non-blocking tcp
681	connections or tcp servers, with IPv6 and SRV record support and more.	930	connections or tcp servers, with IPv6 and SRV record support and more.
682		931
		932	=item L<AnyEvent::Handle>
		933
		934	Provide read and write buffers, manages watchers for reads and writes,
		935	supports raw and formatted I/O, I/O queued and fully transparent and
		936	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		937
683	=item L<AnyEvent::DNS>	938	=item L<AnyEvent::DNS>
684		939
685	Provides rich asynchronous DNS resolver capabilities.	940	Provides rich asynchronous DNS resolver capabilities.
686		941
		942	=item L<AnyEvent::HTTP>
		943
		944	A simple-to-use HTTP library that is capable of making a lot of concurrent
		945	HTTP requests.
		946
687	=item L<AnyEvent::HTTPD>	947	=item L<AnyEvent::HTTPD>
688		948
689	Provides a simple web application server framework.	949	Provides a simple web application server framework.
690		950
691	=item L<AnyEvent::FastPing>	951	=item L<AnyEvent::FastPing>
692		952
693	The fastest ping in the west.	953	The fastest ping in the west.
694		954
		955	=item L<AnyEvent::DBI>
		956
		957	Executes L<DBI> requests asynchronously in a proxy process.
		958
		959	=item L<AnyEvent::AIO>
		960
		961	Truly asynchronous I/O, should be in the toolbox of every event
		962	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		963	together.
		964
		965	=item L<AnyEvent::BDB>
		966
		967	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		968	L<BDB> and AnyEvent together.
		969
		970	=item L<AnyEvent::GPSD>
		971
		972	A non-blocking interface to gpsd, a daemon delivering GPS information.
		973
695	=item L<Net::IRC3>	974	=item L<AnyEvent::IRC>
696		975
697	AnyEvent based IRC client module family.	976	AnyEvent based IRC client module family (replacing the older Net::IRC3).
698		977
699	=item L<Net::XMPP2>	978	=item L<AnyEvent::XMPP>
700		979
701	AnyEvent based XMPP (Jabber protocol) module family.	980	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		981	Net::XMPP2>.
		982
		983	=item L<AnyEvent::IGS>
		984
		985	A non-blocking interface to the Internet Go Server protocol (used by
		986	L<App::IGS>).
702		987
703	=item L<Net::FCP>	988	=item L<Net::FCP>
704		989
705	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	990	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
706	of AnyEvent.	991	of AnyEvent.
…		…
711		996
712	=item L<Coro>	997	=item L<Coro>
713		998
714	Has special support for AnyEvent via L<Coro::AnyEvent>.	999	Has special support for AnyEvent via L<Coro::AnyEvent>.
715		1000
716	=item L<AnyEvent::AIO>, L<IO::AIO>
717
718	Truly asynchronous I/O, should be in the toolbox of every event
719	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
720	together.
721
722	=item L<AnyEvent::BDB>, L<BDB>
723
724	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
725	IO::AIO and AnyEvent together.
726
727	=item L<IO::Lambda>
728
729	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
730
731	=back	1001	=back
732		1002
733	=cut	1003	=cut
734		1004
735	package AnyEvent;	1005	package AnyEvent;
736		1006
737	no warnings;	1007	no warnings;
738	use strict;	1008	use strict qw(vars subs);
739		1009
740	use Carp;	1010	use Carp;
741		1011
742	our $VERSION = '4.05';	1012	our $VERSION = 4.801;
743	our $MODEL;	1013	our $MODEL;
744		1014
745	our $AUTOLOAD;	1015	our $AUTOLOAD;
746	our @ISA;	1016	our @ISA;
747		1017
748	our @REGISTRY;	1018	our @REGISTRY;
749		1019
750	our $WIN32;	1020	our $WIN32;
751		1021
752	BEGIN {	1022	BEGIN {
753	my $win32 = ! ! ($^O =~ /mswin32/i);	1023	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
754	eval "sub WIN32(){ $win32 }";	1024	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1025
		1026	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1027	if ${^TAINT};
755	}	1028	}
756		1029
757	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1030	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
758		1031
759	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1032	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
…		…
770	[Event:: => AnyEvent::Impl::Event::],	1043	[Event:: => AnyEvent::Impl::Event::],
771	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1044	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
772	# everything below here will not be autoprobed	1045	# everything below here will not be autoprobed
773	# as the pureperl backend should work everywhere	1046	# as the pureperl backend should work everywhere
774	# and is usually faster	1047	# and is usually faster
775	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
776	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1048	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
777	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1049	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1050	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1051	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
778	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1052	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
780	[Wx:: => AnyEvent::Impl::POE::],	1053	[Wx:: => AnyEvent::Impl::POE::],
781	[Prima:: => AnyEvent::Impl::POE::],	1054	[Prima:: => AnyEvent::Impl::POE::],
		1055	# IO::Async is just too broken - we would need workarounds for its
		1056	# byzantine signal and broken child handling, among others.
		1057	# IO::Async is rather hard to detect, as it doesn't have any
		1058	# obvious default class.
		1059	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1060	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1061	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
782	);	1062	);
783		1063
784	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1064	our %method = map +($_ => 1),
		1065	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
785		1066
786	our @post_detect;	1067	our @post_detect;
787		1068
788	sub post_detect(&) {	1069	sub post_detect(&) {
789	my ($cb) = @_;	1070	my ($cb) = @_;
…		…
794	1	1075	1
795	} else {	1076	} else {
796	push @post_detect, $cb;	1077	push @post_detect, $cb;
797		1078
798	defined wantarray	1079	defined wantarray
799	? bless \$cb, "AnyEvent::Util::PostDetect"	1080	? bless \$cb, "AnyEvent::Util::postdetect"
800	: ()	1081	: ()
801	}	1082	}
802	}	1083	}
803		1084
804	sub AnyEvent::Util::PostDetect::DESTROY {	1085	sub AnyEvent::Util::postdetect::DESTROY {
805	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1086	@post_detect = grep $_ != ${$_[0]}, @post_detect;
806	}	1087	}
807		1088
808	sub detect() {	1089	sub detect() {
809	unless ($MODEL) {	1090	unless ($MODEL) {
…		…
846	last;	1127	last;
847	}	1128	}
848	}	1129	}
849		1130
850	$MODEL	1131	$MODEL
851	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1132	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
852	}	1133	}
853	}	1134	}
854		1135
		1136	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1137
855	unshift @ISA, $MODEL;	1138	unshift @ISA, $MODEL;
856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1139
		1140	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
857		1141
858	(shift @post_detect)->() while @post_detect;	1142	(shift @post_detect)->() while @post_detect;
859	}	1143	}
860		1144
861	$MODEL	1145	$MODEL
…		…
871		1155
872	my $class = shift;	1156	my $class = shift;
873	$class->$func (@_);	1157	$class->$func (@_);
874	}	1158	}
875		1159
		1160	# utility function to dup a filehandle. this is used by many backends
		1161	# to support binding more than one watcher per filehandle (they usually
		1162	# allow only one watcher per fd, so we dup it to get a different one).
		1163	sub _dupfh($$;$$) {
		1164	my ($poll, $fh, $r, $w) = @_;
		1165
		1166	# cygwin requires the fh mode to be matching, unix doesn't
		1167	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
		1168
		1169	open my $fh2, "$mode&", $fh
		1170	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1171
		1172	# we assume CLOEXEC is already set by perl in all important cases
		1173
		1174	($fh2, $rw)
		1175	}
		1176
876	package AnyEvent::Base;	1177	package AnyEvent::Base;
877		1178
		1179	# default implementations for many methods
		1180
		1181	BEGIN {
		1182	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1183	*_time = \&Time::HiRes::time;
		1184	# if (eval "use POSIX (); (POSIX::times())...
		1185	} else {
		1186	*_time = sub { time }; # epic fail
		1187	}
		1188	}
		1189
		1190	sub time { _time }
		1191	sub now { _time }
		1192	sub now_update { }
		1193
878	# default implementation for ->condvar	1194	# default implementation for ->condvar
879		1195
880	sub condvar {	1196	sub condvar {
881	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1197	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
882	}	1198	}
883		1199
884	# default implementation for ->signal	1200	# default implementation for ->signal
885		1201
886	our %SIG_CB;	1202	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1203
		1204	sub _signal_exec {
		1205	sysread $SIGPIPE_R, my $dummy, 4;
		1206
		1207	while (%SIG_EV) {
		1208	for (keys %SIG_EV) {
		1209	delete $SIG_EV{$_};
		1210	$_->() for values %{ $SIG_CB{$_} || {} };
		1211	}
		1212	}
		1213	}
887		1214
888	sub signal {	1215	sub signal {
889	my (undef, %arg) = @_;	1216	my (undef, %arg) = @_;
890		1217
		1218	unless ($SIGPIPE_R) {
		1219	require Fcntl;
		1220
		1221	if (AnyEvent::WIN32) {
		1222	require AnyEvent::Util;
		1223
		1224	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1225	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1226	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1227	} else {
		1228	pipe $SIGPIPE_R, $SIGPIPE_W;
		1229	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1230	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1231
		1232	# not strictly required, as $^F is normally 2, but let's make sure...
		1233	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1234	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1235	}
		1236
		1237	$SIGPIPE_R
		1238	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1239
		1240	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1241	}
		1242
891	my $signal = uc $arg{signal}	1243	my $signal = uc $arg{signal}
892	or Carp::croak "required option 'signal' is missing";	1244	or Carp::croak "required option 'signal' is missing";
893		1245
894	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1246	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
895	$SIG{$signal} ||= sub {	1247	$SIG{$signal} ||= sub {
896	$_->() for values %{ $SIG_CB{$signal} || {} };	1248	local $!;
		1249	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1250	undef $SIG_EV{$signal};
897	};	1251	};
898		1252
899	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1253	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
900	}	1254	}
901		1255
902	sub AnyEvent::Base::Signal::DESTROY {	1256	sub AnyEvent::Base::signal::DESTROY {
903	my ($signal, $cb) = @{$_[0]};	1257	my ($signal, $cb) = @{$_[0]};
904		1258
905	delete $SIG_CB{$signal}{$cb};	1259	delete $SIG_CB{$signal}{$cb};
906		1260
		1261	# delete doesn't work with older perls - they then
		1262	# print weird messages, or just unconditionally exit
		1263	# instead of getting the default action.
907	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1264	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
908	}	1265	}
909		1266
910	# default implementation for ->child	1267	# default implementation for ->child
911		1268
912	our %PID_CB;	1269	our %PID_CB;
913	our $CHLD_W;	1270	our $CHLD_W;
914	our $CHLD_DELAY_W;	1271	our $CHLD_DELAY_W;
915	our $PID_IDLE;
916	our $WNOHANG;	1272	our $WNOHANG;
917		1273
918	sub _child_wait {	1274	sub _sigchld {
919	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1275	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
920	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1276	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
921	(values %{ $PID_CB{0} || {} });	1277	(values %{ $PID_CB{0} || {} });
922	}	1278	}
923
924	undef $PID_IDLE;
925	}
926
927	sub _sigchld {
928	# make sure we deliver these changes "synchronous" with the event loop.
929	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
930	undef $CHLD_DELAY_W;
931	&_child_wait;
932	});
933	}	1279	}
934		1280
935	sub child {	1281	sub child {
936	my (undef, %arg) = @_;	1282	my (undef, %arg) = @_;
937		1283
938	defined (my $pid = $arg{pid} + 0)	1284	defined (my $pid = $arg{pid} + 0)
939	or Carp::croak "required option 'pid' is missing";	1285	or Carp::croak "required option 'pid' is missing";
940		1286
941	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1287	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
942		1288
943	unless ($WNOHANG) {
944	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1289	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
945	}
946		1290
947	unless ($CHLD_W) {	1291	unless ($CHLD_W) {
948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1292	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
949	# child could be a zombie already, so make at least one round	1293	# child could be a zombie already, so make at least one round
950	&_sigchld;	1294	&_sigchld;
951	}	1295	}
952		1296
953	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1297	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
954	}	1298	}
955		1299
956	sub AnyEvent::Base::Child::DESTROY {	1300	sub AnyEvent::Base::child::DESTROY {
957	my ($pid, $cb) = @{$_[0]};	1301	my ($pid, $cb) = @{$_[0]};
958		1302
959	delete $PID_CB{$pid}{$cb};	1303	delete $PID_CB{$pid}{$cb};
960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1304	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
961		1305
962	undef $CHLD_W unless keys %PID_CB;	1306	undef $CHLD_W unless keys %PID_CB;
		1307	}
		1308
		1309	# idle emulation is done by simply using a timer, regardless
		1310	# of whether the process is idle or not, and not letting
		1311	# the callback use more than 50% of the time.
		1312	sub idle {
		1313	my (undef, %arg) = @_;
		1314
		1315	my ($cb, $w, $rcb) = $arg{cb};
		1316
		1317	$rcb = sub {
		1318	if ($cb) {
		1319	$w = _time;
		1320	&$cb;
		1321	$w = _time - $w;
		1322
		1323	# never use more then 50% of the time for the idle watcher,
		1324	# within some limits
		1325	$w = 0.0001 if $w < 0.0001;
		1326	$w = 5 if $w > 5;
		1327
		1328	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1329	} else {
		1330	# clean up...
		1331	undef $w;
		1332	undef $rcb;
		1333	}
		1334	};
		1335
		1336	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1337
		1338	bless \\$cb, "AnyEvent::Base::idle"
		1339	}
		1340
		1341	sub AnyEvent::Base::idle::DESTROY {
		1342	undef $${$_[0]};
963	}	1343	}
964		1344
965	package AnyEvent::CondVar;	1345	package AnyEvent::CondVar;
966		1346
967	our @ISA = AnyEvent::CondVar::Base::;	1347	our @ISA = AnyEvent::CondVar::Base::;
…		…
1019	}	1399	}
1020		1400
1021	# undocumented/compatibility with pre-3.4	1401	# undocumented/compatibility with pre-3.4
1022	*broadcast = \&send;	1402	*broadcast = \&send;
1023	*wait = \&_wait;	1403	*wait = \&_wait;
		1404
		1405	=head1 ERROR AND EXCEPTION HANDLING
		1406
		1407	In general, AnyEvent does not do any error handling - it relies on the
		1408	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1409	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1410	checking of all AnyEvent methods, however, which is highly useful during
		1411	development.
		1412
		1413	As for exception handling (i.e. runtime errors and exceptions thrown while
		1414	executing a callback), this is not only highly event-loop specific, but
		1415	also not in any way wrapped by this module, as this is the job of the main
		1416	program.
		1417
		1418	The pure perl event loop simply re-throws the exception (usually
		1419	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1420	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1421	so on.
		1422
		1423	=head1 ENVIRONMENT VARIABLES
		1424
		1425	The following environment variables are used by this module or its
		1426	submodules.
		1427
		1428	Note that AnyEvent will remove I<all> environment variables starting with
		1429	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1430	enabled.
		1431
		1432	=over 4
		1433
		1434	=item C<PERL_ANYEVENT_VERBOSE>
		1435
		1436	By default, AnyEvent will be completely silent except in fatal
		1437	conditions. You can set this environment variable to make AnyEvent more
		1438	talkative.
		1439
		1440	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1441	conditions, such as not being able to load the event model specified by
		1442	C<PERL_ANYEVENT_MODEL>.
		1443
		1444	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1445	model it chooses.
		1446
		1447	=item C<PERL_ANYEVENT_STRICT>
		1448
		1449	AnyEvent does not do much argument checking by default, as thorough
		1450	argument checking is very costly. Setting this variable to a true value
		1451	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1452	check the arguments passed to most method calls. If it finds any problems,
		1453	it will croak.
		1454
		1455	In other words, enables "strict" mode.
		1456
		1457	Unlike C<use strict>, it is definitely recommended to keep it off in
		1458	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1459	developing programs can be very useful, however.
		1460
		1461	=item C<PERL_ANYEVENT_MODEL>
		1462
		1463	This can be used to specify the event model to be used by AnyEvent, before
		1464	auto detection and -probing kicks in. It must be a string consisting
		1465	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1466	and the resulting module name is loaded and if the load was successful,
		1467	used as event model. If it fails to load AnyEvent will proceed with
		1468	auto detection and -probing.
		1469
		1470	This functionality might change in future versions.
		1471
		1472	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1473	could start your program like this:
		1474
		1475	PERL_ANYEVENT_MODEL=Perl perl ...
		1476
		1477	=item C<PERL_ANYEVENT_PROTOCOLS>
		1478
		1479	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1480	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1481	of auto probing).
		1482
		1483	Must be set to a comma-separated list of protocols or address families,
		1484	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1485	used, and preference will be given to protocols mentioned earlier in the
		1486	list.
		1487
		1488	This variable can effectively be used for denial-of-service attacks
		1489	against local programs (e.g. when setuid), although the impact is likely
		1490	small, as the program has to handle conenction and other failures anyways.
		1491
		1492	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1493	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1494	- only support IPv4, never try to resolve or contact IPv6
		1495	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1496	IPv6, but prefer IPv6 over IPv4.
		1497
		1498	=item C<PERL_ANYEVENT_EDNS0>
		1499
		1500	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1501	for DNS. This extension is generally useful to reduce DNS traffic, but
		1502	some (broken) firewalls drop such DNS packets, which is why it is off by
		1503	default.
		1504
		1505	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1506	EDNS0 in its DNS requests.
		1507
		1508	=item C<PERL_ANYEVENT_MAX_FORKS>
		1509
		1510	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1511	will create in parallel.
		1512
		1513	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1514
		1515	The default value for the C<max_outstanding> parameter for the default DNS
		1516	resolver - this is the maximum number of parallel DNS requests that are
		1517	sent to the DNS server.
		1518
		1519	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1520
		1521	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1522	configuration) in the default resolver. When set to the empty string, no
		1523	default config will be used.
		1524
		1525	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1526
		1527	When neither C<ca_file> nor C<ca_path> was specified during
		1528	L<AnyEvent::TLS> context creation, and either of these environment
		1529	variables exist, they will be used to specify CA certificate locations
		1530	instead of a system-dependent default.
		1531
		1532	=back
1024		1533
1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1534	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1026		1535
1027	This is an advanced topic that you do not normally need to use AnyEvent in	1536	This is an advanced topic that you do not normally need to use AnyEvent in
1028	a module. This section is only of use to event loop authors who want to	1537	a module. This section is only of use to event loop authors who want to
…		…
1062		1571
1063	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1572	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1064	condition variables: code blocking while waiting for a condition will	1573	condition variables: code blocking while waiting for a condition will
1065	C<die>. This still works with most modules/usages, and blocking calls must	1574	C<die>. This still works with most modules/usages, and blocking calls must
1066	not be done in an interactive application, so it makes sense.	1575	not be done in an interactive application, so it makes sense.
1067
1068	=head1 ENVIRONMENT VARIABLES
1069
1070	The following environment variables are used by this module:
1071
1072	=over 4
1073
1074	=item C<PERL_ANYEVENT_VERBOSE>
1075
1076	By default, AnyEvent will be completely silent except in fatal
1077	conditions. You can set this environment variable to make AnyEvent more
1078	talkative.
1079
1080	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1081	conditions, such as not being able to load the event model specified by
1082	C<PERL_ANYEVENT_MODEL>.
1083
1084	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1085	model it chooses.
1086
1087	=item C<PERL_ANYEVENT_MODEL>
1088
1089	This can be used to specify the event model to be used by AnyEvent, before
1090	auto detection and -probing kicks in. It must be a string consisting
1091	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1092	and the resulting module name is loaded and if the load was successful,
1093	used as event model. If it fails to load AnyEvent will proceed with
1094	auto detection and -probing.
1095
1096	This functionality might change in future versions.
1097
1098	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1099	could start your program like this:
1100
1101	PERL_ANYEVENT_MODEL=Perl perl ...
1102
1103	=item C<PERL_ANYEVENT_PROTOCOLS>
1104
1105	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1106	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1107	of auto probing).
1108
1109	Must be set to a comma-separated list of protocols or address families,
1110	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1111	used, and preference will be given to protocols mentioned earlier in the
1112	list.
1113
1114	This variable can effectively be used for denial-of-service attacks
1115	against local programs (e.g. when setuid), although the impact is likely
1116	small, as the program has to handle connection errors already-
1117
1118	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1119	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1120	- only support IPv4, never try to resolve or contact IPv6
1121	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1122	IPv6, but prefer IPv6 over IPv4.
1123
1124	=item C<PERL_ANYEVENT_EDNS0>
1125
1126	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1127	for DNS. This extension is generally useful to reduce DNS traffic, but
1128	some (broken) firewalls drop such DNS packets, which is why it is off by
1129	default.
1130
1131	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1132	EDNS0 in its DNS requests.
1133
1134	=item C<PERL_ANYEVENT_MAX_FORKS>
1135
1136	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1137	will create in parallel.
1138
1139	=back
1140		1576
1141	=head1 EXAMPLE PROGRAM	1577	=head1 EXAMPLE PROGRAM
1142		1578
1143	The following program uses an I/O watcher to read data from STDIN, a timer	1579	The following program uses an I/O watcher to read data from STDIN, a timer
1144	to display a message once per second, and a condition variable to quit the	1580	to display a message once per second, and a condition variable to quit the
…		…
1338	watcher.	1774	watcher.
1339		1775
1340	=head3 Results	1776	=head3 Results
1341		1777
1342	name watchers bytes create invoke destroy comment	1778	name watchers bytes create invoke destroy comment
1343	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1779	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1344	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1780	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1345	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1781	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1346	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1782	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1347	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1783	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1348	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1784	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1785	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1786	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1349	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1787	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1350	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1788	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1351	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1789	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1352	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1790	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1353		1791
1354	=head3 Discussion	1792	=head3 Discussion
1355		1793
1356	The benchmark does I<not> measure scalability of the event loop very	1794	The benchmark does I<not> measure scalability of the event loop very
1357	well. For example, a select-based event loop (such as the pure perl one)	1795	well. For example, a select-based event loop (such as the pure perl one)
…		…
1382	performance becomes really bad with lots of file descriptors (and few of	1820	performance becomes really bad with lots of file descriptors (and few of
1383	them active), of course, but this was not subject of this benchmark.	1821	them active), of course, but this was not subject of this benchmark.
1384		1822
1385	The C<Event> module has a relatively high setup and callback invocation	1823	The C<Event> module has a relatively high setup and callback invocation
1386	cost, but overall scores in on the third place.	1824	cost, but overall scores in on the third place.
		1825
		1826	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1827	when using its pure perl backend.
1387		1828
1388	C<Glib>'s memory usage is quite a bit higher, but it features a	1829	C<Glib>'s memory usage is quite a bit higher, but it features a
1389	faster callback invocation and overall ends up in the same class as	1830	faster callback invocation and overall ends up in the same class as
1390	C<Event>. However, Glib scales extremely badly, doubling the number of	1831	C<Event>. However, Glib scales extremely badly, doubling the number of
1391	watchers increases the processing time by more than a factor of four,	1832	watchers increases the processing time by more than a factor of four,
…		…
1469	it to another server. This includes deleting the old timeout and creating	1910	it to another server. This includes deleting the old timeout and creating
1470	a new one that moves the timeout into the future.	1911	a new one that moves the timeout into the future.
1471		1912
1472	=head3 Results	1913	=head3 Results
1473		1914
1474	name sockets create request	1915	name sockets create request
1475	EV 20000 69.01 11.16	1916	EV 20000 69.01 11.16
1476	Perl 20000 73.32 35.87	1917	Perl 20000 73.32 35.87
		1918	IOAsync 20000 157.00 98.14 epoll
		1919	IOAsync 20000 159.31 616.06 poll
1477	Event 20000 212.62 257.32	1920	Event 20000 212.62 257.32
1478	Glib 20000 651.16 1896.30	1921	Glib 20000 651.16 1896.30
1479	POE 20000 349.67 12317.24 uses POE::Loop::Event	1922	POE 20000 349.67 12317.24 uses POE::Loop::Event
1480		1923
1481	=head3 Discussion	1924	=head3 Discussion
1482		1925
1483	This benchmark I<does> measure scalability and overall performance of the	1926	This benchmark I<does> measure scalability and overall performance of the
1484	particular event loop.	1927	particular event loop.
…		…
1486	EV is again fastest. Since it is using epoll on my system, the setup time	1929	EV is again fastest. Since it is using epoll on my system, the setup time
1487	is relatively high, though.	1930	is relatively high, though.
1488		1931
1489	Perl surprisingly comes second. It is much faster than the C-based event	1932	Perl surprisingly comes second. It is much faster than the C-based event
1490	loops Event and Glib.	1933	loops Event and Glib.
		1934
		1935	IO::Async performs very well when using its epoll backend, and still quite
		1936	good compared to Glib when using its pure perl backend.
1491		1937
1492	Event suffers from high setup time as well (look at its code and you will	1938	Event suffers from high setup time as well (look at its code and you will
1493	understand why). Callback invocation also has a high overhead compared to	1939	understand why). Callback invocation also has a high overhead compared to
1494	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1940	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1495	uses select or poll in basically all documented configurations.	1941	uses select or poll in basically all documented configurations.
…		…
1558	=item * C-based event loops perform very well with small number of	2004	=item * C-based event loops perform very well with small number of
1559	watchers, as the management overhead dominates.	2005	watchers, as the management overhead dominates.
1560		2006
1561	=back	2007	=back
1562		2008
		2009	=head2 THE IO::Lambda BENCHMARK
		2010
		2011	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2012	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2013	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2014	shouldn't come as a surprise to anybody). As such, the benchmark is
		2015	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2016	very optimal. But how would AnyEvent compare when used without the extra
		2017	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2018
		2019	The benchmark itself creates an echo-server, and then, for 500 times,
		2020	connects to the echo server, sends a line, waits for the reply, and then
		2021	creates the next connection. This is a rather bad benchmark, as it doesn't
		2022	test the efficiency of the framework or much non-blocking I/O, but it is a
		2023	benchmark nevertheless.
		2024
		2025	name runtime
		2026	Lambda/select 0.330 sec
		2027	+ optimized 0.122 sec
		2028	Lambda/AnyEvent 0.327 sec
		2029	+ optimized 0.138 sec
		2030	Raw sockets/select 0.077 sec
		2031	POE/select, components 0.662 sec
		2032	POE/select, raw sockets 0.226 sec
		2033	POE/select, optimized 0.404 sec
		2034
		2035	AnyEvent/select/nb 0.085 sec
		2036	AnyEvent/EV/nb 0.068 sec
		2037	+state machine 0.134 sec
		2038
		2039	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2040	benchmarks actually make blocking connects and use 100% blocking I/O,
		2041	defeating the purpose of an event-based solution. All of the newly
		2042	written AnyEvent benchmarks use 100% non-blocking connects (using
		2043	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2044	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2045	generally require a lot more bookkeeping and event handling than blocking
		2046	connects (which involve a single syscall only).
		2047
		2048	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2049	offers similar expressive power as POE and IO::Lambda, using conventional
		2050	Perl syntax. This means that both the echo server and the client are 100%
		2051	non-blocking, further placing it at a disadvantage.
		2052
		2053	As you can see, the AnyEvent + EV combination even beats the
		2054	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2055	backend easily beats IO::Lambda and POE.
		2056
		2057	And even the 100% non-blocking version written using the high-level (and
		2058	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2059	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2060	in a non-blocking way.
		2061
		2062	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2063	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2064	part of the IO::lambda distribution and were used without any changes.
		2065
		2066
		2067	=head1 SIGNALS
		2068
		2069	AnyEvent currently installs handlers for these signals:
		2070
		2071	=over 4
		2072
		2073	=item SIGCHLD
		2074
		2075	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2076	emulation for event loops that do not support them natively. Also, some
		2077	event loops install a similar handler.
		2078
		2079	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2080	reset it to default, to avoid losing child exit statuses.
		2081
		2082	=item SIGPIPE
		2083
		2084	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2085	when AnyEvent gets loaded.
		2086
		2087	The rationale for this is that AnyEvent users usually do not really depend
		2088	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2089	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2090	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2091	some random socket.
		2092
		2093	The rationale for installing a no-op handler as opposed to ignoring it is
		2094	that this way, the handler will be restored to defaults on exec.
		2095
		2096	Feel free to install your own handler, or reset it to defaults.
		2097
		2098	=back
		2099
		2100	=cut
		2101
		2102	undef $SIG{CHLD}
		2103	if $SIG{CHLD} eq 'IGNORE';
		2104
		2105	$SIG{PIPE} = sub { }
		2106	unless defined $SIG{PIPE};
1563		2107
1564	=head1 FORK	2108	=head1 FORK
1565		2109
1566	Most event libraries are not fork-safe. The ones who are usually are	2110	Most event libraries are not fork-safe. The ones who are usually are
1567	because they rely on inefficient but fork-safe C<select> or C<poll>	2111	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1581	specified in the variable.	2125	specified in the variable.
1582		2126
1583	You can make AnyEvent completely ignore this variable by deleting it	2127	You can make AnyEvent completely ignore this variable by deleting it
1584	before the first watcher gets created, e.g. with a C<BEGIN> block:	2128	before the first watcher gets created, e.g. with a C<BEGIN> block:
1585		2129
1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2130	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1587		2131
1588	use AnyEvent;	2132	use AnyEvent;
1589		2133
1590	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2134	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1591	be used to probe what backend is used and gain other information (which is	2135	be used to probe what backend is used and gain other information (which is
1592	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2136	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2137	$ENV{PERL_ANYEVENT_STRICT}.
		2138
		2139	Note that AnyEvent will remove I<all> environment variables starting with
		2140	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2141	enabled.
		2142
		2143
		2144	=head1 BUGS
		2145
		2146	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2147	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2148	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2149	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2150	pronounced).
1593		2151
1594		2152
1595	=head1 SEE ALSO	2153	=head1 SEE ALSO
1596		2154
1597	Utility functions: L<AnyEvent::Util>.	2155	Utility functions: L<AnyEvent::Util>.
…		…
1600	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2158	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1601		2159
1602	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2160	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1603	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2161	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1604	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2162	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1605	L<AnyEvent::Impl::POE>.	2163	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1606		2164
1607	Non-blocking file handles, sockets, TCP clients and	2165	Non-blocking file handles, sockets, TCP clients and
1608	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2166	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1609		2167
1610	Asynchronous DNS: L<AnyEvent::DNS>.	2168	Asynchronous DNS: L<AnyEvent::DNS>.
1611		2169
1612	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2170	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2171	L<Coro::Event>,
1613		2172
1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2173	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2174	L<AnyEvent::HTTP>.
1615		2175
1616		2176
1617	=head1 AUTHOR	2177	=head1 AUTHOR
1618		2178
1619	Marc Lehmann <schmorp@schmorp.de>	2179	Marc Lehmann <schmorp@schmorp.de>
1620	http://home.schmorp.de/	2180	http://home.schmorp.de/
1621		2181
1622	=cut	2182	=cut
1623		2183
1624	1	2184	1
1625		2185

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