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Revision 1.91 by root, Sat Apr 26 02:27:30 2008 UTC vs.
Revision 1.196 by root, Thu Mar 26 07:47:42 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, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
		12
		13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
12	...	23	...
13	});	24	});
14		25
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...
17	});
18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		27	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	28	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	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	47	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,	48	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,	49	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	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	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	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	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	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	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	61	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	62	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	63	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	64	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.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	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	69	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,	70	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	71	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	72	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	73	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).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	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	77	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	78	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	79	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	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	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	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70
71		92
72	=head1 DESCRIPTION	93	=head1 DESCRIPTION
73		94
74	L<AnyEvent> provides an identical interface to multiple event loops. This	95	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	96	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	101	module.
81		102
82	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
…		…
103	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
104	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
105		126
106	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
109		130
110	=head1 WATCHERS	131	=head1 WATCHERS
111		132
112	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
115		136
116	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
119	is in control).	140	is in control).
120		141
		142	Note that B<callbacks must not permanently change global variables>
		143	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		144	callbacks must not C<die> >>. The former is good programming practise in
		145	Perl and the latter stems from the fact that exception handling differs
		146	widely between event loops.
		147
121	To disable the watcher you have to destroy it (e.g. by setting the	148	To disable the watcher you have to destroy it (e.g. by setting the
122	variable you store it in to C<undef> or otherwise deleting all references	149	variable you store it in to C<undef> or otherwise deleting all references
123	to it).	150	to it).
124		151
125	All watchers are created by calling a method on the C<AnyEvent> class.	152	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
127	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
128	example), or need to refer to their watcher object in other ways.	155	example), or need to refer to their watcher object in other ways.
129		156
130	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
131		158
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
134	undef $w;	161	undef $w;
135	});	162	});
136		163
137	Note that C<my $w; $w => combination. This is necessary because in Perl,	164	Note that C<my $w; $w => combination. This is necessary because in Perl,
138	my variables are only visible after the statement in which they are	165	my variables are only visible after the statement in which they are
139	declared.	166	declared.
140		167
141	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
142		169
143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
145		172
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	173	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
147	for events. C<poll> must be a string that is either C<r> or C<w>,	174	(AnyEvent might or might not keep a reference to this file handle). C<poll>
148	which creates a watcher waiting for "r"eadable or "w"ritable events,	175	must be a string that is either C<r> or C<w>, which creates a watcher
149	respectively. C<cb> is the callback to invoke each time the file handle	176	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
150	becomes ready.	177	callback to invoke each time the file handle becomes ready.
151		178
152	Although the callback might get passed parameters, their value and	179	Although the callback might get passed parameters, their value and
153	presence is undefined and you cannot rely on them. Portable AnyEvent	180	presence is undefined and you cannot rely on them. Portable AnyEvent
154	callbacks cannot use arguments passed to I/O watcher callbacks.	181	callbacks cannot use arguments passed to I/O watcher callbacks.
155		182
…		…
159		186
160	Some event loops issue spurious readyness notifications, so you should	187	Some event loops issue spurious readyness notifications, so you should
161	always use non-blocking calls when reading/writing from/to your file	188	always use non-blocking calls when reading/writing from/to your file
162	handles.	189	handles.
163		190
164	Example:
165
166	# wait for readability of STDIN, then read a line and disable the watcher	191	Example: wait for readability of STDIN, then read a line and disable the
		192	watcher.
		193
167	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	194	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
168	chomp (my $input = <STDIN>);	195	chomp (my $input = <STDIN>);
169	warn "read: $input\n";	196	warn "read: $input\n";
170	undef $w;	197	undef $w;
171	});	198	});
…		…
181		208
182	Although the callback might get passed parameters, their value and	209	Although the callback might get passed parameters, their value and
183	presence is undefined and you cannot rely on them. Portable AnyEvent	210	presence is undefined and you cannot rely on them. Portable AnyEvent
184	callbacks cannot use arguments passed to time watcher callbacks.	211	callbacks cannot use arguments passed to time watcher callbacks.
185		212
186	The timer callback will be invoked at most once: if you want a repeating	213	The callback will normally be invoked once only. If you specify another
187	timer you have to create a new watcher (this is a limitation by both Tk	214	parameter, C<interval>, as a strictly positive number (> 0), then the
188	and Glib).	215	callback will be invoked regularly at that interval (in fractional
		216	seconds) after the first invocation. If C<interval> is specified with a
		217	false value, then it is treated as if it were missing.
189		218
190	Example:	219	The callback will be rescheduled before invoking the callback, but no
		220	attempt is done to avoid timer drift in most backends, so the interval is
		221	only approximate.
191		222
192	# fire an event after 7.7 seconds	223	Example: fire an event after 7.7 seconds.
		224
193	my $w = AnyEvent->timer (after => 7.7, cb => sub {	225	my $w = AnyEvent->timer (after => 7.7, cb => sub {
194	warn "timeout\n";	226	warn "timeout\n";
195	});	227	});
196		228
197	# to cancel the timer:	229	# to cancel the timer:
198	undef $w;	230	undef $w;
199		231
200	Example 2:
201
202	# fire an event after 0.5 seconds, then roughly every second	232	Example 2: fire an event after 0.5 seconds, then roughly every second.
203	my $w;
204		233
205	my $cb = sub {
206	# cancel the old timer while creating a new one
207	$w = AnyEvent->timer (after => 1, cb => $cb);	234	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		235	warn "timeout\n";
208	};	236	};
209
210	# start the "loop" by creating the first watcher
211	$w = AnyEvent->timer (after => 0.5, cb => $cb);
212		237
213	=head3 TIMING ISSUES	238	=head3 TIMING ISSUES
214		239
215	There are two ways to handle timers: based on real time (relative, "fire	240	There are two ways to handle timers: based on real time (relative, "fire
216	in 10 seconds") and based on wallclock time (absolute, "fire at 12	241	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
228	timers.	253	timers.
229		254
230	AnyEvent always prefers relative timers, if available, matching the	255	AnyEvent always prefers relative timers, if available, matching the
231	AnyEvent API.	256	AnyEvent API.
232		257
		258	AnyEvent has two additional methods that return the "current time":
		259
		260	=over 4
		261
		262	=item AnyEvent->time
		263
		264	This returns the "current wallclock time" as a fractional number of
		265	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		266	return, and the result is guaranteed to be compatible with those).
		267
		268	It progresses independently of any event loop processing, i.e. each call
		269	will check the system clock, which usually gets updated frequently.
		270
		271	=item AnyEvent->now
		272
		273	This also returns the "current wallclock time", but unlike C<time>, above,
		274	this value might change only once per event loop iteration, depending on
		275	the event loop (most return the same time as C<time>, above). This is the
		276	time that AnyEvent's timers get scheduled against.
		277
		278	I<In almost all cases (in all cases if you don't care), this is the
		279	function to call when you want to know the current time.>
		280
		281	This function is also often faster then C<< AnyEvent->time >>, and
		282	thus the preferred method if you want some timestamp (for example,
		283	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		284
		285	The rest of this section is only of relevance if you try to be very exact
		286	with your timing, you can skip it without bad conscience.
		287
		288	For a practical example of when these times differ, consider L<Event::Lib>
		289	and L<EV> and the following set-up:
		290
		291	The event loop is running and has just invoked one of your callback at
		292	time=500 (assume no other callbacks delay processing). In your callback,
		293	you wait a second by executing C<sleep 1> (blocking the process for a
		294	second) and then (at time=501) you create a relative timer that fires
		295	after three seconds.
		296
		297	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		298	both return C<501>, because that is the current time, and the timer will
		299	be scheduled to fire at time=504 (C<501> + C<3>).
		300
		301	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		302	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		303	last event processing phase started. With L<EV>, your timer gets scheduled
		304	to run at time=503 (C<500> + C<3>).
		305
		306	In one sense, L<Event::Lib> is more exact, as it uses the current time
		307	regardless of any delays introduced by event processing. However, most
		308	callbacks do not expect large delays in processing, so this causes a
		309	higher drift (and a lot more system calls to get the current time).
		310
		311	In another sense, L<EV> is more exact, as your timer will be scheduled at
		312	the same time, regardless of how long event processing actually took.
		313
		314	In either case, if you care (and in most cases, you don't), then you
		315	can get whatever behaviour you want with any event loop, by taking the
		316	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		317	account.
		318
		319	=back
		320
233	=head2 SIGNAL WATCHERS	321	=head2 SIGNAL WATCHERS
234		322
235	You can watch for signals using a signal watcher, C<signal> is the signal	323	You can watch for signals using a signal watcher, C<signal> is the signal
236	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	324	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
237	be invoked whenever a signal occurs.	325	callback to be invoked whenever a signal occurs.
238		326
239	Although the callback might get passed parameters, their value and	327	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	328	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	329	callbacks cannot use arguments passed to signal watcher callbacks.
242		330
243	Multiple signal occurances can be clumped together into one callback	331	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	332	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	333	that it might take a while until the signal gets handled by the process,
246	but it is guarenteed not to interrupt any other callbacks.	334	but it is guaranteed not to interrupt any other callbacks.
247		335
248	The main advantage of using these watchers is that you can share a signal	336	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	337	between multiple watchers.
250		338
251	This watcher might use C<%SIG>, so programs overwriting those signals	339	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
258	=head2 CHILD PROCESS WATCHERS	346	=head2 CHILD PROCESS WATCHERS
259		347
260	You can also watch on a child process exit and catch its exit status.	348	You can also watch on a child process exit and catch its exit status.
261		349
262	The child process is specified by the C<pid> argument (if set to C<0>, it	350	The child process is specified by the C<pid> argument (if set to C<0>, it
263	watches for any child process exit). The watcher will trigger as often	351	watches for any child process exit). The watcher will triggered only when
264	as status change for the child are received. This works by installing a	352	the child process has finished and an exit status is available, not on
265	signal handler for C<SIGCHLD>. The callback will be called with the pid	353	any trace events (stopped/continued).
266	and exit status (as returned by waitpid), so unlike other watcher types,	354
267	you I<can> rely on child watcher callback arguments.	355	The callback will be called with the pid and exit status (as returned by
		356	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		357	callback arguments.
		358
		359	This watcher type works by installing a signal handler for C<SIGCHLD>,
		360	and since it cannot be shared, nothing else should use SIGCHLD or reap
		361	random child processes (waiting for specific child processes, e.g. inside
		362	C<system>, is just fine).
268		363
269	There is a slight catch to child watchers, however: you usually start them	364	There is a slight catch to child watchers, however: you usually start them
270	I<after> the child process was created, and this means the process could	365	I<after> the child process was created, and this means the process could
271	have exited already (and no SIGCHLD will be sent anymore).	366	have exited already (and no SIGCHLD will be sent anymore).
272		367
…		…
278	AnyEvent program, you I<have> to create at least one watcher before you	373	AnyEvent program, you I<have> to create at least one watcher before you
279	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	374	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
280		375
281	Example: fork a process and wait for it	376	Example: fork a process and wait for it
282		377
283	my $done = AnyEvent->condvar;	378	my $done = AnyEvent->condvar;
284		379
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	380	my $pid = fork or exit 5;
288		381
289	my $w = AnyEvent->child (	382	my $w = AnyEvent->child (
290	pid => $pid,	383	pid => $pid,
291	cb => sub {	384	cb => sub {
292	my ($pid, $status) = @_;	385	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	386	warn "pid $pid exited with status $status";
294	$done->broadcast;	387	$done->send;
295	},	388	},
296	);	389	);
297		390
298	# do something else, then wait for process exit	391	# do something else, then wait for process exit
299	$done->wait;	392	$done->recv;
300		393
301	=head2 CONDITION VARIABLES	394	=head2 CONDITION VARIABLES
302		395
		396	If you are familiar with some event loops you will know that all of them
		397	require you to run some blocking "loop", "run" or similar function that
		398	will actively watch for new events and call your callbacks.
		399
		400	AnyEvent is different, it expects somebody else to run the event loop and
		401	will only block when necessary (usually when told by the user).
		402
		403	The instrument to do that is called a "condition variable", so called
		404	because they represent a condition that must become true.
		405
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	406	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	407	>> method, usually without arguments. The only argument pair allowed is
305		408
306	A condition variable waits for a condition - precisely that the C<<	409	C<cb>, which specifies a callback to be called when the condition variable
307	->broadcast >> method has been called.	410	becomes true, with the condition variable as the first argument (but not
		411	the results).
308		412
309	They are very useful to signal that a condition has been fulfilled, for	413	After creation, the condition variable is "false" until it becomes "true"
		414	by calling the C<send> method (or calling the condition variable as if it
		415	were a callback, read about the caveats in the description for the C<<
		416	->send >> method).
		417
		418	Condition variables are similar to callbacks, except that you can
		419	optionally wait for them. They can also be called merge points - points
		420	in time where multiple outstanding events have been processed. And yet
		421	another way to call them is transactions - each condition variable can be
		422	used to represent a transaction, which finishes at some point and delivers
		423	a result.
		424
		425	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	426	for example, if you write a module that does asynchronous http requests,
311	then a condition variable would be the ideal candidate to signal the	427	then a condition variable would be the ideal candidate to signal the
312	availability of results.	428	availability of results. The user can either act when the callback is
		429	called or can synchronously C<< ->recv >> for the results.
313		430
314	You can also use condition variables to block your main program until	431	You can also use them to simulate traditional event loops - for example,
315	an event occurs - for example, you could C<< ->wait >> in your main	432	you can block your main program until an event occurs - for example, you
316	program until the user clicks the Quit button in your app, which would C<<	433	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	434	button of your app, which would C<< ->send >> the "quit" event.
318		435
319	Note that condition variables recurse into the event loop - if you have	436	Note that condition variables recurse into the event loop - if you have
320	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	437	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
321	lose. Therefore, condition variables are good to export to your caller, but	438	lose. Therefore, condition variables are good to export to your caller, but
322	you should avoid making a blocking wait yourself, at least in callbacks,	439	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	440	as this asks for trouble.
324		441
325	This object has two methods:	442	Condition variables are represented by hash refs in perl, and the keys
		443	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		444	easy (it is often useful to build your own transaction class on top of
		445	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		446	it's C<new> method in your own C<new> method.
		447
		448	There are two "sides" to a condition variable - the "producer side" which
		449	eventually calls C<< -> send >>, and the "consumer side", which waits
		450	for the send to occur.
		451
		452	Example: wait for a timer.
		453
		454	# wait till the result is ready
		455	my $result_ready = AnyEvent->condvar;
		456
		457	# do something such as adding a timer
		458	# or socket watcher the calls $result_ready->send
		459	# when the "result" is ready.
		460	# in this case, we simply use a timer:
		461	my $w = AnyEvent->timer (
		462	after => 1,
		463	cb => sub { $result_ready->send },
		464	);
		465
		466	# this "blocks" (while handling events) till the callback
		467	# calls send
		468	$result_ready->recv;
		469
		470	Example: wait for a timer, but take advantage of the fact that
		471	condition variables are also code references.
		472
		473	my $done = AnyEvent->condvar;
		474	my $delay = AnyEvent->timer (after => 5, cb => $done);
		475	$done->recv;
		476
		477	Example: Imagine an API that returns a condvar and doesn't support
		478	callbacks. This is how you make a synchronous call, for example from
		479	the main program:
		480
		481	use AnyEvent::CouchDB;
		482
		483	...
		484
		485	my @info = $couchdb->info->recv;
		486
		487	And this is how you would just ste a callback to be called whenever the
		488	results are available:
		489
		490	$couchdb->info->cb (sub {
		491	my @info = $_[0]->recv;
		492	});
		493
		494	=head3 METHODS FOR PRODUCERS
		495
		496	These methods should only be used by the producing side, i.e. the
		497	code/module that eventually sends the signal. Note that it is also
		498	the producer side which creates the condvar in most cases, but it isn't
		499	uncommon for the consumer to create it as well.
326		500
327	=over 4	501	=over 4
328		502
		503	=item $cv->send (...)
		504
		505	Flag the condition as ready - a running C<< ->recv >> and all further
		506	calls to C<recv> will (eventually) return after this method has been
		507	called. If nobody is waiting the send will be remembered.
		508
		509	If a callback has been set on the condition variable, it is called
		510	immediately from within send.
		511
		512	Any arguments passed to the C<send> call will be returned by all
		513	future C<< ->recv >> calls.
		514
		515	Condition variables are overloaded so one can call them directly
		516	(as a code reference). Calling them directly is the same as calling
		517	C<send>. Note, however, that many C-based event loops do not handle
		518	overloading, so as tempting as it may be, passing a condition variable
		519	instead of a callback does not work. Both the pure perl and EV loops
		520	support overloading, however, as well as all functions that use perl to
		521	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		522	example).
		523
		524	=item $cv->croak ($error)
		525
		526	Similar to send, but causes all call's to C<< ->recv >> to invoke
		527	C<Carp::croak> with the given error message/object/scalar.
		528
		529	This can be used to signal any errors to the condition variable
		530	user/consumer.
		531
		532	=item $cv->begin ([group callback])
		533
329	=item $cv->wait	534	=item $cv->end
330		535
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		537
		538	These two methods can be used to combine many transactions/events into
		539	one. For example, a function that pings many hosts in parallel might want
		540	to use a condition variable for the whole process.
		541
		542	Every call to C<< ->begin >> will increment a counter, and every call to
		543	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		544	>>, the (last) callback passed to C<begin> will be executed. That callback
		545	is I<supposed> to call C<< ->send >>, but that is not required. If no
		546	callback was set, C<send> will be called without any arguments.
		547
		548	Let's clarify this with the ping example:
		549
		550	my $cv = AnyEvent->condvar;
		551
		552	my %result;
		553	$cv->begin (sub { $cv->send (\%result) });
		554
		555	for my $host (@list_of_hosts) {
		556	$cv->begin;
		557	ping_host_then_call_callback $host, sub {
		558	$result{$host} = ...;
		559	$cv->end;
		560	};
		561	}
		562
		563	$cv->end;
		564
		565	This code fragment supposedly pings a number of hosts and calls
		566	C<send> after results for all then have have been gathered - in any
		567	order. To achieve this, the code issues a call to C<begin> when it starts
		568	each ping request and calls C<end> when it has received some result for
		569	it. Since C<begin> and C<end> only maintain a counter, the order in which
		570	results arrive is not relevant.
		571
		572	There is an additional bracketing call to C<begin> and C<end> outside the
		573	loop, which serves two important purposes: first, it sets the callback
		574	to be called once the counter reaches C<0>, and second, it ensures that
		575	C<send> is called even when C<no> hosts are being pinged (the loop
		576	doesn't execute once).
		577
		578	This is the general pattern when you "fan out" into multiple subrequests:
		579	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		580	is called at least once, and then, for each subrequest you start, call
		581	C<begin> and for each subrequest you finish, call C<end>.
		582
		583	=back
		584
		585	=head3 METHODS FOR CONSUMERS
		586
		587	These methods should only be used by the consuming side, i.e. the
		588	code awaits the condition.
		589
		590	=over 4
		591
		592	=item $cv->recv
		593
		594	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	595	>> methods have been called on c<$cv>, while servicing other watchers
		596	normally.
333		597
334	You can only wait once on a condition - additional calls will return	598	You can only wait once on a condition - additional calls are valid but
335	immediately.	599	will return immediately.
		600
		601	If an error condition has been set by calling C<< ->croak >>, then this
		602	function will call C<croak>.
		603
		604	In list context, all parameters passed to C<send> will be returned,
		605	in scalar context only the first one will be returned.
336		606
337	Not all event models support a blocking wait - some die in that case	607	Not all event models support a blocking wait - some die in that case
338	(programs might want to do that to stay interactive), so I<if you are	608	(programs might want to do that to stay interactive), so I<if you are
339	using this from a module, never require a blocking wait>, but let the	609	using this from a module, never require a blocking wait>, but let the
340	caller decide whether the call will block or not (for example, by coupling	610	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	611	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	612	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	613	while still supporting blocking waits if the caller so desires).
344		614
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	615	Another reason I<never> to C<< ->recv >> in a module is that you cannot
346	sensibly have two C<< ->wait >>'s in parallel, as that would require	616	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	618	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		619
352	=item $cv->broadcast	620	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		621	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		622	versions and also integrates coroutines into AnyEvent, making blocking
		623	C<< ->recv >> calls perfectly safe as long as they are done from another
		624	coroutine (one that doesn't run the event loop).
353		625
354	Flag the condition as ready - a running C<< ->wait >> and all further	626	You can ensure that C<< -recv >> never blocks by setting a callback and
355	calls to C<wait> will (eventually) return after this method has been	627	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	628	time). This will work even when the event loop does not support blocking
		629	waits otherwise.
		630
		631	=item $bool = $cv->ready
		632
		633	Returns true when the condition is "true", i.e. whether C<send> or
		634	C<croak> have been called.
		635
		636	=item $cb = $cv->cb ($cb->($cv))
		637
		638	This is a mutator function that returns the callback set and optionally
		639	replaces it before doing so.
		640
		641	The callback will be called when the condition becomes "true", i.e. when
		642	C<send> or C<croak> are called, with the only argument being the condition
		643	variable itself. Calling C<recv> inside the callback or at any later time
		644	is guaranteed not to block.
357		645
358	=back	646	=back
359
360	Example:
361
362	# wait till the result is ready
363	my $result_ready = AnyEvent->condvar;
364
365	# do something such as adding a timer
366	# or socket watcher the calls $result_ready->broadcast
367	# when the "result" is ready.
368	# in this case, we simply use a timer:
369	my $w = AnyEvent->timer (
370	after => 1,
371	cb => sub { $result_ready->broadcast },
372	);
373
374	# this "blocks" (while handling events) till the watcher
375	# calls broadcast
376	$result_ready->wait;
377		647
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	648	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		649
380	=over 4	650	=over 4
381		651
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		659
390	The known classes so far are:	660	The known classes so far are:
391		661
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	663	AnyEvent::Impl::Event based on Event, second best choice.
		664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	665	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	666	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	667	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	668	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	669	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		670
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	684	if necessary. You should only call this function right before you would
417	have created an AnyEvent watcher anyway, that is, as late as possible at	685	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	686	runtime.
419		687
		688	=item $guard = AnyEvent::post_detect { BLOCK }
		689
		690	Arranges for the code block to be executed as soon as the event model is
		691	autodetected (or immediately if this has already happened).
		692
		693	If called in scalar or list context, then it creates and returns an object
		694	that automatically removes the callback again when it is destroyed. See
		695	L<Coro::BDB> for a case where this is useful.
		696
		697	=item @AnyEvent::post_detect
		698
		699	If there are any code references in this array (you can C<push> to it
		700	before or after loading AnyEvent), then they will called directly after
		701	the event loop has been chosen.
		702
		703	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		704	if it contains a true value then the event loop has already been detected,
		705	and the array will be ignored.
		706
		707	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		708
420	=back	709	=back
421		710
422	=head1 WHAT TO DO IN A MODULE	711	=head1 WHAT TO DO IN A MODULE
423		712
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	713	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
427	Be careful when you create watchers in the module body - AnyEvent will	716	Be careful when you create watchers in the module body - AnyEvent will
428	decide which event module to use as soon as the first method is called, so	717	decide which event module to use as soon as the first method is called, so
429	by calling AnyEvent in your module body you force the user of your module	718	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	719	to load the event module first.
431		720
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	721	Never call C<< ->recv >> on a condition variable unless you I<know> that
433	the C<< ->broadcast >> method has been called on it already. This is	722	the C<< ->send >> method has been called on it already. This is
434	because it will stall the whole program, and the whole point of using	723	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	724	events is to stay interactive.
436		725
437	It is fine, however, to call C<< ->wait >> when the user of your module	726	It is fine, however, to call C<< ->recv >> when the user of your module
438	requests it (i.e. if you create a http request object ad have a method	727	requests it (i.e. if you create a http request object ad have a method
439	called C<results> that returns the results, it should call C<< ->wait >>	728	called C<results> that returns the results, it should call C<< ->recv >>
440	freely, as the user of your module knows what she is doing. always).	729	freely, as the user of your module knows what she is doing. always).
441		730
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	731	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		732
444	There will always be a single main program - the only place that should	733	There will always be a single main program - the only place that should
…		…
446		735
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	736	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
448	do anything special (it does not need to be event-based) and let AnyEvent	737	do anything special (it does not need to be event-based) and let AnyEvent
449	decide which implementation to chose if some module relies on it.	738	decide which implementation to chose if some module relies on it.
450		739
451	If the main program relies on a specific event model. For example, in	740	If the main program relies on a specific event model - for example, in
452	Gtk2 programs you have to rely on the Glib module. You should load the	741	Gtk2 programs you have to rely on the Glib module - you should load the
453	event module before loading AnyEvent or any module that uses it: generally	742	event module before loading AnyEvent or any module that uses it: generally
454	speaking, you should load it as early as possible. The reason is that	743	speaking, you should load it as early as possible. The reason is that
455	modules might create watchers when they are loaded, and AnyEvent will	744	modules might create watchers when they are loaded, and AnyEvent will
456	decide on the event model to use as soon as it creates watchers, and it	745	decide on the event model to use as soon as it creates watchers, and it
457	might chose the wrong one unless you load the correct one yourself.	746	might chose the wrong one unless you load the correct one yourself.
458		747
459	You can chose to use a rather inefficient pure-perl implementation by	748	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	749	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	750	everywhere, but letting AnyEvent chose the model is generally better.
		751
		752	=head2 MAINLOOP EMULATION
		753
		754	Sometimes (often for short test scripts, or even standalone programs who
		755	only want to use AnyEvent), you do not want to run a specific event loop.
		756
		757	In that case, you can use a condition variable like this:
		758
		759	AnyEvent->condvar->recv;
		760
		761	This has the effect of entering the event loop and looping forever.
		762
		763	Note that usually your program has some exit condition, in which case
		764	it is better to use the "traditional" approach of storing a condition
		765	variable somewhere, waiting for it, and sending it when the program should
		766	exit cleanly.
		767
		768
		769	=head1 OTHER MODULES
		770
		771	The following is a non-exhaustive list of additional modules that use
		772	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		773	in the same program. Some of the modules come with AnyEvent, some are
		774	available via CPAN.
		775
		776	=over 4
		777
		778	=item L<AnyEvent::Util>
		779
		780	Contains various utility functions that replace often-used but blocking
		781	functions such as C<inet_aton> by event-/callback-based versions.
		782
		783	=item L<AnyEvent::Socket>
		784
		785	Provides various utility functions for (internet protocol) sockets,
		786	addresses and name resolution. Also functions to create non-blocking tcp
		787	connections or tcp servers, with IPv6 and SRV record support and more.
		788
		789	=item L<AnyEvent::Handle>
		790
		791	Provide read and write buffers, manages watchers for reads and writes,
		792	supports raw and formatted I/O, I/O queued and fully transparent and
		793	non-blocking SSL/TLS.
		794
		795	=item L<AnyEvent::DNS>
		796
		797	Provides rich asynchronous DNS resolver capabilities.
		798
		799	=item L<AnyEvent::HTTP>
		800
		801	A simple-to-use HTTP library that is capable of making a lot of concurrent
		802	HTTP requests.
		803
		804	=item L<AnyEvent::HTTPD>
		805
		806	Provides a simple web application server framework.
		807
		808	=item L<AnyEvent::FastPing>
		809
		810	The fastest ping in the west.
		811
		812	=item L<AnyEvent::DBI>
		813
		814	Executes L<DBI> requests asynchronously in a proxy process.
		815
		816	=item L<AnyEvent::AIO>
		817
		818	Truly asynchronous I/O, should be in the toolbox of every event
		819	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		820	together.
		821
		822	=item L<AnyEvent::BDB>
		823
		824	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		825	L<BDB> and AnyEvent together.
		826
		827	=item L<AnyEvent::GPSD>
		828
		829	A non-blocking interface to gpsd, a daemon delivering GPS information.
		830
		831	=item L<AnyEvent::IGS>
		832
		833	A non-blocking interface to the Internet Go Server protocol (used by
		834	L<App::IGS>).
		835
		836	=item L<AnyEvent::IRC>
		837
		838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		839
		840	=item L<Net::XMPP2>
		841
		842	AnyEvent based XMPP (Jabber protocol) module family.
		843
		844	=item L<Net::FCP>
		845
		846	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		847	of AnyEvent.
		848
		849	=item L<Event::ExecFlow>
		850
		851	High level API for event-based execution flow control.
		852
		853	=item L<Coro>
		854
		855	Has special support for AnyEvent via L<Coro::AnyEvent>.
		856
		857	=item L<IO::Lambda>
		858
		859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		860
		861	=back
462		862
463	=cut	863	=cut
464		864
465	package AnyEvent;	865	package AnyEvent;
466		866
467	no warnings;	867	no warnings;
468	use strict;	868	use strict qw(vars subs);
469		869
470	use Carp;	870	use Carp;
471		871
472	our $VERSION = '3.3';	872	our $VERSION = 4.341;
473	our $MODEL;	873	our $MODEL;
474		874
475	our $AUTOLOAD;	875	our $AUTOLOAD;
476	our @ISA;	876	our @ISA;
477		877
		878	our @REGISTRY;
		879
		880	our $WIN32;
		881
		882	BEGIN {
		883	my $win32 = ! ! ($^O =~ /mswin32/i);
		884	eval "sub WIN32(){ $win32 }";
		885	}
		886
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		888
480	our @REGISTRY;	889	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		890
		891	{
		892	my $idx;
		893	$PROTOCOL{$_} = ++$idx
		894	for reverse split /\s*,\s*/,
		895	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		896	}
481		897
482	my @models = (	898	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	899	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	900	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	902	# everything below here will not be autoprobed
		903	# as the pureperl backend should work everywhere
		904	# and is usually faster
		905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		910	[Wx:: => AnyEvent::Impl::POE::],
		911	[Prima:: => AnyEvent::Impl::POE::],
496	);	912	);
497		913
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	914	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		915
		916	our @post_detect;
		917
		918	sub post_detect(&) {
		919	my ($cb) = @_;
		920
		921	if ($MODEL) {
		922	$cb->();
		923
		924	1
		925	} else {
		926	push @post_detect, $cb;
		927
		928	defined wantarray
		929	? bless \$cb, "AnyEvent::Util::PostDetect"
		930	: ()
		931	}
		932	}
		933
		934	sub AnyEvent::Util::PostDetect::DESTROY {
		935	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		936	}
499		937
500	sub detect() {	938	sub detect() {
501	unless ($MODEL) {	939	unless ($MODEL) {
502	no strict 'refs';	940	no strict 'refs';
		941	local $SIG{__DIE__};
503		942
504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
505	my $model = "AnyEvent::Impl::$1";	944	my $model = "AnyEvent::Impl::$1";
506	if (eval "require $model") {	945	if (eval "require $model") {
507	$MODEL = $model;	946	$MODEL = $model;
…		…
537	last;	976	last;
538	}	977	}
539	}	978	}
540		979
541	$MODEL	980	$MODEL
542	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	982	}
544	}	983	}
545		984
		985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		986
546	unshift @ISA, $MODEL;	987	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	988
		989	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		990
		991	(shift @post_detect)->() while @post_detect;
548	}	992	}
549		993
550	$MODEL	994	$MODEL
551	}	995	}
552		996
…		…
560		1004
561	my $class = shift;	1005	my $class = shift;
562	$class->$func (@_);	1006	$class->$func (@_);
563	}	1007	}
564		1008
		1009	# utility function to dup a filehandle. this is used by many backends
		1010	# to support binding more than one watcher per filehandle (they usually
		1011	# allow only one watcher per fd, so we dup it to get a different one).
		1012	sub _dupfh($$$$) {
		1013	my ($poll, $fh, $r, $w) = @_;
		1014
		1015	# cygwin requires the fh mode to be matching, unix doesn't
		1016	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1017	: $poll eq "w" ? ($w, ">")
		1018	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1019
		1020	open my $fh2, "$mode&" . fileno $fh
		1021	or die "cannot dup() filehandle: $!";
		1022
		1023	# we assume CLOEXEC is already set by perl in all important cases
		1024
		1025	($fh2, $rw)
		1026	}
		1027
565	package AnyEvent::Base;	1028	package AnyEvent::Base;
566		1029
		1030	# default implementation for now and time
		1031
		1032	BEGIN {
		1033	if (eval "use Time::HiRes (); time (); 1") {
		1034	*_time = \&Time::HiRes::time;
		1035	# if (eval "use POSIX (); (POSIX::times())...
		1036	} else {
		1037	*_time = sub { time }; # epic fail
		1038	}
		1039	}
		1040
		1041	sub time { _time }
		1042	sub now { _time }
		1043
567	# default implementation for ->condvar, ->wait, ->broadcast	1044	# default implementation for ->condvar
568		1045
569	sub condvar {	1046	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
571	}
572
573	sub AnyEvent::Base::CondVar::broadcast {
574	${$_[0]}++;
575	}
576
577	sub AnyEvent::Base::CondVar::wait {
578	AnyEvent->one_event while !${$_[0]};
579	}	1048	}
580		1049
581	# default implementation for ->signal	1050	# default implementation for ->signal
582		1051
583	our %SIG_CB;	1052	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1053
		1054	sub _signal_exec {
		1055	while (%SIG_EV) {
		1056	sysread $SIGPIPE_R, my $dummy, 4;
		1057	for (keys %SIG_EV) {
		1058	delete $SIG_EV{$_};
		1059	$_->() for values %{ $SIG_CB{$_} || {} };
		1060	}
		1061	}
		1062	}
584		1063
585	sub signal {	1064	sub signal {
586	my (undef, %arg) = @_;	1065	my (undef, %arg) = @_;
587		1066
		1067	unless ($SIGPIPE_R) {
		1068	if (AnyEvent::WIN32) {
		1069	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1070	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1071	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1072	} else {
		1073	pipe $SIGPIPE_R, $SIGPIPE_W;
		1074	require Fcntl;
		1075	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1076	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1077	}
		1078
		1079	$SIGPIPE_R
		1080	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1081
		1082	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1083	}
		1084
588	my $signal = uc $arg{signal}	1085	my $signal = uc $arg{signal}
589	or Carp::croak "required option 'signal' is missing";	1086	or Carp::croak "required option 'signal' is missing";
590		1087
591	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1088	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
592	$SIG{$signal} ||= sub {	1089	$SIG{$signal} ||= sub {
593	$_->() for values %{ $SIG_CB{$signal} || {} };	1090	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1091	undef $SIG_EV{$signal};
594	};	1092	};
595		1093
596	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1094	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
597	}	1095	}
598		1096
599	sub AnyEvent::Base::Signal::DESTROY {	1097	sub AnyEvent::Base::Signal::DESTROY {
600	my ($signal, $cb) = @{$_[0]};	1098	my ($signal, $cb) = @{$_[0]};
601		1099
602	delete $SIG_CB{$signal}{$cb};	1100	delete $SIG_CB{$signal}{$cb};
603		1101
604	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1102	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
605	}	1103	}
606		1104
607	# default implementation for ->child	1105	# default implementation for ->child
608		1106
609	our %PID_CB;	1107	our %PID_CB;
…		…
636	or Carp::croak "required option 'pid' is missing";	1134	or Carp::croak "required option 'pid' is missing";
637		1135
638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1136	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
639		1137
640	unless ($WNOHANG) {	1138	unless ($WNOHANG) {
641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1139	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
642	}	1140	}
643		1141
644	unless ($CHLD_W) {	1142	unless ($CHLD_W) {
645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1143	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
646	# child could be a zombie already, so make at least one round	1144	# child could be a zombie already, so make at least one round
…		…
656	delete $PID_CB{$pid}{$cb};	1154	delete $PID_CB{$pid}{$cb};
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1155	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		1156
659	undef $CHLD_W unless keys %PID_CB;	1157	undef $CHLD_W unless keys %PID_CB;
660	}	1158	}
		1159
		1160	package AnyEvent::CondVar;
		1161
		1162	our @ISA = AnyEvent::CondVar::Base::;
		1163
		1164	package AnyEvent::CondVar::Base;
		1165
		1166	use overload
		1167	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1168	fallback => 1;
		1169
		1170	sub _send {
		1171	# nop
		1172	}
		1173
		1174	sub send {
		1175	my $cv = shift;
		1176	$cv->{_ae_sent} = [@_];
		1177	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1178	$cv->_send;
		1179	}
		1180
		1181	sub croak {
		1182	$_[0]{_ae_croak} = $_[1];
		1183	$_[0]->send;
		1184	}
		1185
		1186	sub ready {
		1187	$_[0]{_ae_sent}
		1188	}
		1189
		1190	sub _wait {
		1191	AnyEvent->one_event while !$_[0]{_ae_sent};
		1192	}
		1193
		1194	sub recv {
		1195	$_[0]->_wait;
		1196
		1197	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1198	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1199	}
		1200
		1201	sub cb {
		1202	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1203	$_[0]{_ae_cb}
		1204	}
		1205
		1206	sub begin {
		1207	++$_[0]{_ae_counter};
		1208	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1209	}
		1210
		1211	sub end {
		1212	return if --$_[0]{_ae_counter};
		1213	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1214	}
		1215
		1216	# undocumented/compatibility with pre-3.4
		1217	*broadcast = \&send;
		1218	*wait = \&_wait;
		1219
		1220	=head1 ERROR AND EXCEPTION HANDLING
		1221
		1222	In general, AnyEvent does not do any error handling - it relies on the
		1223	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1224	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1225	checking of all AnyEvent methods, however, which is highly useful during
		1226	development.
		1227
		1228	As for exception handling (i.e. runtime errors and exceptions thrown while
		1229	executing a callback), this is not only highly event-loop specific, but
		1230	also not in any way wrapped by this module, as this is the job of the main
		1231	program.
		1232
		1233	The pure perl event loop simply re-throws the exception (usually
		1234	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1235	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1236	so on.
		1237
		1238	=head1 ENVIRONMENT VARIABLES
		1239
		1240	The following environment variables are used by this module or its
		1241	submodules:
		1242
		1243	=over 4
		1244
		1245	=item C<PERL_ANYEVENT_VERBOSE>
		1246
		1247	By default, AnyEvent will be completely silent except in fatal
		1248	conditions. You can set this environment variable to make AnyEvent more
		1249	talkative.
		1250
		1251	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1252	conditions, such as not being able to load the event model specified by
		1253	C<PERL_ANYEVENT_MODEL>.
		1254
		1255	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1256	model it chooses.
		1257
		1258	=item C<PERL_ANYEVENT_STRICT>
		1259
		1260	AnyEvent does not do much argument checking by default, as thorough
		1261	argument checking is very costly. Setting this variable to a true value
		1262	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1263	check the arguments passed to most method calls. If it finds any problems
		1264	it will croak.
		1265
		1266	In other words, enables "strict" mode.
		1267
		1268	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1269	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1270	developing programs can be very useful, however.
		1271
		1272	=item C<PERL_ANYEVENT_MODEL>
		1273
		1274	This can be used to specify the event model to be used by AnyEvent, before
		1275	auto detection and -probing kicks in. It must be a string consisting
		1276	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1277	and the resulting module name is loaded and if the load was successful,
		1278	used as event model. If it fails to load AnyEvent will proceed with
		1279	auto detection and -probing.
		1280
		1281	This functionality might change in future versions.
		1282
		1283	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1284	could start your program like this:
		1285
		1286	PERL_ANYEVENT_MODEL=Perl perl ...
		1287
		1288	=item C<PERL_ANYEVENT_PROTOCOLS>
		1289
		1290	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1291	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1292	of auto probing).
		1293
		1294	Must be set to a comma-separated list of protocols or address families,
		1295	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1296	used, and preference will be given to protocols mentioned earlier in the
		1297	list.
		1298
		1299	This variable can effectively be used for denial-of-service attacks
		1300	against local programs (e.g. when setuid), although the impact is likely
		1301	small, as the program has to handle conenction and other failures anyways.
		1302
		1303	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1304	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1305	- only support IPv4, never try to resolve or contact IPv6
		1306	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1307	IPv6, but prefer IPv6 over IPv4.
		1308
		1309	=item C<PERL_ANYEVENT_EDNS0>
		1310
		1311	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1312	for DNS. This extension is generally useful to reduce DNS traffic, but
		1313	some (broken) firewalls drop such DNS packets, which is why it is off by
		1314	default.
		1315
		1316	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1317	EDNS0 in its DNS requests.
		1318
		1319	=item C<PERL_ANYEVENT_MAX_FORKS>
		1320
		1321	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1322	will create in parallel.
		1323
		1324	=back
661		1325
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1326	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1327
664	This is an advanced topic that you do not normally need to use AnyEvent in	1328	This is an advanced topic that you do not normally need to use AnyEvent in
665	a module. This section is only of use to event loop authors who want to	1329	a module. This section is only of use to event loop authors who want to
…		…
699		1363
700	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1364	I<rxvt-unicode> also cheats a bit by not providing blocking access to
701	condition variables: code blocking while waiting for a condition will	1365	condition variables: code blocking while waiting for a condition will
702	C<die>. This still works with most modules/usages, and blocking calls must	1366	C<die>. This still works with most modules/usages, and blocking calls must
703	not be done in an interactive application, so it makes sense.	1367	not be done in an interactive application, so it makes sense.
704
705	=head1 ENVIRONMENT VARIABLES
706
707	The following environment variables are used by this module:
708
709	=over 4
710
711	=item C<PERL_ANYEVENT_VERBOSE>
712
713	By default, AnyEvent will be completely silent except in fatal
714	conditions. You can set this environment variable to make AnyEvent more
715	talkative.
716
717	When set to C<1> or higher, causes AnyEvent to warn about unexpected
718	conditions, such as not being able to load the event model specified by
719	C<PERL_ANYEVENT_MODEL>.
720
721	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
722	model it chooses.
723
724	=item C<PERL_ANYEVENT_MODEL>
725
726	This can be used to specify the event model to be used by AnyEvent, before
727	autodetection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
729	and the resulting module name is loaded and if the load was successful,
730	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.
732
733	This functionality might change in future versions.
734
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:
737
738	PERL_ANYEVENT_MODEL=Perl perl ...
739
740	=back
741		1368
742	=head1 EXAMPLE PROGRAM	1369	=head1 EXAMPLE PROGRAM
743		1370
744	The following program uses an I/O watcher to read data from STDIN, a timer	1371	The following program uses an I/O watcher to read data from STDIN, a timer
745	to display a message once per second, and a condition variable to quit the	1372	to display a message once per second, and a condition variable to quit the
…		…
754	poll => 'r',	1381	poll => 'r',
755	cb => sub {	1382	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1383	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1384	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1385	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1386	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1387	},
761	);	1388	);
762		1389
763	my $time_watcher; # can only be used once	1390	my $time_watcher; # can only be used once
764		1391
…		…
769	});	1396	});
770	}	1397	}
771		1398
772	new_timer; # create first timer	1399	new_timer; # create first timer
773		1400
774	$cv->wait; # wait until user enters /^q/i	1401	$cv->recv; # wait until user enters /^q/i
775		1402
776	=head1 REAL-WORLD EXAMPLE	1403	=head1 REAL-WORLD EXAMPLE
777		1404
778	Consider the L<Net::FCP> module. It features (among others) the following	1405	Consider the L<Net::FCP> module. It features (among others) the following
779	API calls, which are to freenet what HTTP GET requests are to http:	1406	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1456	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1457	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1458	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1459
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1460	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
834	result and signals any possible waiters that the request ahs finished:	1461	result and signals any possible waiters that the request has finished:
835		1462
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1463	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1464
838	if (end-of-file or data complete) {	1465	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1466	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1467	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1468	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1469	}
843		1470
844	The C<result> method, finally, just waits for the finished signal (if the	1471	The C<result> method, finally, just waits for the finished signal (if the
845	request was already finished, it doesn't wait, of course, and returns the	1472	request was already finished, it doesn't wait, of course, and returns the
846	data:	1473	data:
847		1474
848	$txn->{finished}->wait;	1475	$txn->{finished}->recv;
849	return $txn->{result};	1476	return $txn->{result};
850		1477
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1478	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1479	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1480	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1481	and just throws the exception, which means connection errors and other
855	problems get reported tot he code that tries to use the result, not in a	1482	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1483	random callback.
857		1484
…		…
888		1515
889	my $quit = AnyEvent->condvar;	1516	my $quit = AnyEvent->condvar;
890		1517
891	$fcp->txn_client_get ($url)->cb (sub {	1518	$fcp->txn_client_get ($url)->cb (sub {
892	...	1519	...
893	$quit->broadcast;	1520	$quit->send;
894	});	1521	});
895		1522
896	$quit->wait;	1523	$quit->recv;
897		1524
898		1525
899	=head1 BENCHMARKS	1526	=head1 BENCHMARKS
900		1527
901	To give you an idea of the performance and overheads that AnyEvent adds	1528	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1530	of various event loops I prepared some benchmarks.
904		1531
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1532	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1533
907	Here is a benchmark of various supported event models used natively and	1534	Here is a benchmark of various supported event models used natively and
908	through anyevent. The benchmark creates a lot of timers (with a zero	1535	through AnyEvent. The benchmark creates a lot of timers (with a zero
909	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1536	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
910	which it is), lets them fire exactly once and destroys them again.	1537	which it is), lets them fire exactly once and destroys them again.
911		1538
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1539	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1540	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1557	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1558	and memory usage is not included in the figures.
932		1559
933	I<invoke> is the time, in microseconds, used to invoke a simple	1560	I<invoke> is the time, in microseconds, used to invoke a simple
934	callback. The callback simply counts down a Perl variable and after it was	1561	callback. The callback simply counts down a Perl variable and after it was
935	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1562	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1563	signal the end of this phase.
937		1564
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1565	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1566	watcher.
940		1567
941	=head3 Results	1568	=head3 Results
942		1569
943	name watchers bytes create invoke destroy comment	1570	name watchers bytes create invoke destroy comment
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1571	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
945	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1572	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
946	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1573	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
947	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1574	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
948	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1575	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
949	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1576	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
950	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1577	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
951	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1578	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
952	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1579	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
953	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1580	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
954		1581
955	=head3 Discussion	1582	=head3 Discussion
956		1583
957	The benchmark does I<not> measure scalability of the event loop very	1584	The benchmark does I<not> measure scalability of the event loop very
958	well. For example, a select-based event loop (such as the pure perl one)	1585	well. For example, a select-based event loop (such as the pure perl one)
959	can never compete with an event loop that uses epoll when the number of	1586	can never compete with an event loop that uses epoll when the number of
960	file descriptors grows high. In this benchmark, all events become ready at	1587	file descriptors grows high. In this benchmark, all events become ready at
961	the same time, so select/poll-based implementations get an unnatural speed	1588	the same time, so select/poll-based implementations get an unnatural speed
962	boost.	1589	boost.
		1590
		1591	Also, note that the number of watchers usually has a nonlinear effect on
		1592	overall speed, that is, creating twice as many watchers doesn't take twice
		1593	the time - usually it takes longer. This puts event loops tested with a
		1594	higher number of watchers at a disadvantage.
		1595
		1596	To put the range of results into perspective, consider that on the
		1597	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1598	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1599	cycles with POE.
963		1600
964	C<EV> is the sole leader regarding speed and memory use, which are both	1601	C<EV> is the sole leader regarding speed and memory use, which are both
965	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1602	maximal/minimal, respectively. Even when going through AnyEvent, it uses
966	far less memory than any other event loop and is still faster than Event	1603	far less memory than any other event loop and is still faster than Event
967	natively.	1604	natively.
…		…
990	file descriptor is dup()ed for each watcher. This shows that the dup()	1627	file descriptor is dup()ed for each watcher. This shows that the dup()
991	employed by some adaptors is not a big performance issue (it does incur a	1628	employed by some adaptors is not a big performance issue (it does incur a
992	hidden memory cost inside the kernel which is not reflected in the figures	1629	hidden memory cost inside the kernel which is not reflected in the figures
993	above).	1630	above).
994		1631
995	C<POE>, regardless of underlying event loop (whether using its pure	1632	C<POE>, regardless of underlying event loop (whether using its pure perl
996	perl select-based backend or the Event module, the POE-EV backend	1633	select-based backend or the Event module, the POE-EV backend couldn't
997	couldn't be tested because it wasn't working) shows abysmal performance	1634	be tested because it wasn't working) shows abysmal performance and
998	and memory usage: Watchers use almost 30 times as much memory as	1635	memory usage with AnyEvent: Watchers use almost 30 times as much memory
999	EV watchers, and 10 times as much memory as Event (the high memory	1636	as EV watchers, and 10 times as much memory as Event (the high memory
1000	requirements are caused by requiring a session for each watcher). Watcher	1637	requirements are caused by requiring a session for each watcher). Watcher
1001	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1638	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1639	implementation.
		1640
1002	implementation. The design of the POE adaptor class in AnyEvent can not	1641	The design of the POE adaptor class in AnyEvent can not really account
1003	really account for this, as session creation overhead is small compared	1642	for the performance issues, though, as session creation overhead is
1004	to execution of the state machine, which is coded pretty optimally within	1643	small compared to execution of the state machine, which is coded pretty
1005	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1644	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1645	using multiple sessions is not a good approach, especially regarding
		1646	memory usage, even the author of POE could not come up with a faster
		1647	design).
1006		1648
1007	=head3 Summary	1649	=head3 Summary
1008		1650
1009	=over 4	1651	=over 4
1010		1652
…		…
1021		1663
1022	=back	1664	=back
1023		1665
1024	=head2 BENCHMARKING THE LARGE SERVER CASE	1666	=head2 BENCHMARKING THE LARGE SERVER CASE
1025		1667
1026	This benchmark atcually benchmarks the event loop itself. It works by	1668	This benchmark actually benchmarks the event loop itself. It works by
1027	creating a number of "servers": each server consists of a socketpair, a	1669	creating a number of "servers": each server consists of a socket pair, a
1028	timeout watcher that gets reset on activity (but never fires), and an I/O	1670	timeout watcher that gets reset on activity (but never fires), and an I/O
1029	watcher waiting for input on one side of the socket. Each time the socket	1671	watcher waiting for input on one side of the socket. Each time the socket
1030	watcher reads a byte it will write that byte to a random other "server".	1672	watcher reads a byte it will write that byte to a random other "server".
1031		1673
1032	The effect is that there will be a lot of I/O watchers, only part of which	1674	The effect is that there will be a lot of I/O watchers, only part of which
1033	are active at any one point (so there is a constant number of active	1675	are active at any one point (so there is a constant number of active
1034	fds for each loop iterstaion, but which fds these are is random). The	1676	fds for each loop iteration, but which fds these are is random). The
1035	timeout is reset each time something is read because that reflects how	1677	timeout is reset each time something is read because that reflects how
1036	most timeouts work (and puts extra pressure on the event loops).	1678	most timeouts work (and puts extra pressure on the event loops).
1037		1679
1038	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1680	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1039	(1%) are active. This mirrors the activity of large servers with many	1681	(1%) are active. This mirrors the activity of large servers with many
1040	connections, most of which are idle during at any one point in time.	1682	connections, most of which are idle at any one point in time.
1041		1683
1042	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1684	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1043	distribution.	1685	distribution.
1044		1686
1045	=head3 Explanation of the columns	1687	=head3 Explanation of the columns
1046		1688
1047	I<sockets> is the number of sockets, and twice the number of "servers" (as	1689	I<sockets> is the number of sockets, and twice the number of "servers" (as
1048	eahc server has a read and write socket end).	1690	each server has a read and write socket end).
1049		1691
1050	I<create> is the time it takes to create a socketpair (which is	1692	I<create> is the time it takes to create a socket pair (which is
1051	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1693	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1052		1694
1053	I<request>, the most important value, is the time it takes to handle a	1695	I<request>, the most important value, is the time it takes to handle a
1054	single "request", that is, reading the token from the pipe and forwarding	1696	single "request", that is, reading the token from the pipe and forwarding
1055	it to another server. This includes deleteing the old timeout and creating	1697	it to another server. This includes deleting the old timeout and creating
1056	a new one with a later timeout.	1698	a new one that moves the timeout into the future.
1057		1699
1058	=head3 Results	1700	=head3 Results
1059		1701
1060	name sockets create request	1702	name sockets create request
1061	EV 20000 69.01 11.16	1703	EV 20000 69.01 11.16
1062	Perl 20000 75.28 112.76	1704	Perl 20000 73.32 35.87
1063	Event 20000 212.62 257.32	1705	Event 20000 212.62 257.32
1064	Glib 20000 651.16 1896.30	1706	Glib 20000 651.16 1896.30
1065	POE 20000 349.67 12317.24 uses POE::Loop::Event	1707	POE 20000 349.67 12317.24 uses POE::Loop::Event
1066		1708
1067	=head3 Discussion	1709	=head3 Discussion
…		…
1089		1731
1090	=head3 Summary	1732	=head3 Summary
1091		1733
1092	=over 4	1734	=over 4
1093		1735
1094	=item * The pure perl implementation performs extremely well, considering	1736	=item * The pure perl implementation performs extremely well.
1095	that it uses select.
1096		1737
1097	=item * Avoid Glib or POE in large projects where performance matters.	1738	=item * Avoid Glib or POE in large projects where performance matters.
1098		1739
1099	=back	1740	=back
1100		1741
…		…
1113		1754
1114	=head3 Results	1755	=head3 Results
1115		1756
1116	name sockets create request	1757	name sockets create request
1117	EV 16 20.00 6.54	1758	EV 16 20.00 6.54
		1759	Perl 16 25.75 12.62
1118	Event 16 81.27 35.86	1760	Event 16 81.27 35.86
1119	Glib 16 32.63 15.48	1761	Glib 16 32.63 15.48
1120	Perl 16 24.62 162.37
1121	POE 16 261.87 276.28 uses POE::Loop::Event	1762	POE 16 261.87 276.28 uses POE::Loop::Event
1122		1763
1123	=head3 Discussion	1764	=head3 Discussion
1124		1765
1125	The benchmark tries to test the performance of a typical small	1766	The benchmark tries to test the performance of a typical small
1126	server. While knowing how various event loops perform is interesting, keep	1767	server. While knowing how various event loops perform is interesting, keep
1127	in mind that their overhead in this case is usually not as important, due	1768	in mind that their overhead in this case is usually not as important, due
1128	to the small absolute number of watchers.	1769	to the small absolute number of watchers (that is, you need efficiency and
		1770	speed most when you have lots of watchers, not when you only have a few of
		1771	them).
1129		1772
1130	EV is again fastest.	1773	EV is again fastest.
1131		1774
1132	The C-based event loops Event and Glib come in second this time, as the	1775	Perl again comes second. It is noticeably faster than the C-based event
1133	overhead of running an iteration is much smaller in C than in Perl (little	1776	loops Event and Glib, although the difference is too small to really
1134	code to execute in the inner loop, and perl's function calling overhead is	1777	matter.
1135	high, and updating all the data structures is costly).
1136		1778
1137	The pure perl event loop is much slower, but still competitive.
1138
1139	POE also performs much better in this case, but is is stillf ar behind the	1779	POE also performs much better in this case, but is is still far behind the
1140	others.	1780	others.
1141		1781
1142	=head3 Summary	1782	=head3 Summary
1143		1783
1144	=over 4	1784	=over 4
…		…
1147	watchers, as the management overhead dominates.	1787	watchers, as the management overhead dominates.
1148		1788
1149	=back	1789	=back
1150		1790
1151		1791
		1792	=head1 SIGNALS
		1793
		1794	AnyEvent currently installs handlers for these signals:
		1795
		1796	=over 4
		1797
		1798	=item SIGCHLD
		1799
		1800	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1801	emulation for event loops that do not support them natively. Also, some
		1802	event loops install a similar handler.
		1803
		1804	=item SIGPIPE
		1805
		1806	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1807	when AnyEvent gets loaded.
		1808
		1809	The rationale for this is that AnyEvent users usually do not really depend
		1810	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1811	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1812	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1813	some random socket.
		1814
		1815	The rationale for installing a no-op handler as opposed to ignoring it is
		1816	that this way, the handler will be restored to defaults on exec.
		1817
		1818	Feel free to install your own handler, or reset it to defaults.
		1819
		1820	=back
		1821
		1822	=cut
		1823
		1824	$SIG{PIPE} = sub { }
		1825	unless defined $SIG{PIPE};
		1826
		1827
1152	=head1 FORK	1828	=head1 FORK
1153		1829
1154	Most event libraries are not fork-safe. The ones who are usually are	1830	Most event libraries are not fork-safe. The ones who are usually are
1155	because they are so inefficient. Only L<EV> is fully fork-aware.	1831	because they rely on inefficient but fork-safe C<select> or C<poll>
		1832	calls. Only L<EV> is fully fork-aware.
1156		1833
1157	If you have to fork, you must either do so I<before> creating your first	1834	If you have to fork, you must either do so I<before> creating your first
1158	watcher OR you must not use AnyEvent at all in the child.	1835	watcher OR you must not use AnyEvent at all in the child.
1159		1836
1160		1837
…		…
1168	specified in the variable.	1845	specified in the variable.
1169		1846
1170	You can make AnyEvent completely ignore this variable by deleting it	1847	You can make AnyEvent completely ignore this variable by deleting it
1171	before the first watcher gets created, e.g. with a C<BEGIN> block:	1848	before the first watcher gets created, e.g. with a C<BEGIN> block:
1172		1849
1173	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1850	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1174		1851
1175	use AnyEvent;	1852	use AnyEvent;
		1853
		1854	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1855	be used to probe what backend is used and gain other information (which is
		1856	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1857	$ENV{PERL_ANYEGENT_STRICT}.
		1858
		1859
		1860	=head1 BUGS
		1861
		1862	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1863	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1864	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1865	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1866	pronounced).
1176		1867
1177		1868
1178	=head1 SEE ALSO	1869	=head1 SEE ALSO
1179		1870
1180	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1871	Utility functions: L<AnyEvent::Util>.
1181	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1872
		1873	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1182	L<Event::Lib>, L<Qt>, L<POE>.	1874	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1183		1875
1184	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1876	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1185	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1877	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1186	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1878	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1187	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1879	L<AnyEvent::Impl::POE>.
1188		1880
		1881	Non-blocking file handles, sockets, TCP clients and
		1882	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1883
		1884	Asynchronous DNS: L<AnyEvent::DNS>.
		1885
		1886	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1887
1189	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1888	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1190		1889
1191		1890
1192	=head1 AUTHOR	1891	=head1 AUTHOR
1193		1892
1194	Marc Lehmann <schmorp@schmorp.de>	1893	Marc Lehmann <schmorp@schmorp.de>
1195	http://home.schmorp.de/	1894	http://home.schmorp.de/
1196		1895
1197	=cut	1896	=cut
1198		1897
1199	1	1898	1
1200		1899

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