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Revision 1.105 by root, Thu May 1 12:35:54 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		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
…		…
78	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>
79	module.	101	module.
80		102
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
114		136
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	140	is in control).
119		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
120	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
121	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
122	to it).	150	to it).
123		151
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		156
129	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
130		158
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
133	undef $w;	161	undef $w;
134	});	162	});
135		163
136	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,
137	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
138	declared.	166	declared.
139		167
140	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
141		169
142	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
143	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
144		172
145	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
146	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>
147	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
148	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
149	becomes ready.	177	callback to invoke each time the file handle becomes ready.
150		178
151	Although the callback might get passed parameters, their value and	179	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	180	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	181	callbacks cannot use arguments passed to I/O watcher callbacks.
154		182
…		…
158		186
159	Some event loops issue spurious readyness notifications, so you should	187	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	189	handles.
162		190
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	194	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	195	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	196	warn "read: $input\n";
169	undef $w;	197	undef $w;
170	});	198	});
…		…
180		208
181	Although the callback might get passed parameters, their value and	209	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	210	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	211	callbacks cannot use arguments passed to time watcher callbacks.
184		212
185	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
186	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
187	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.
188		218
189	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.
190		222
191	# fire an event after 7.7 seconds	223	Example: fire an event after 7.7 seconds.
		224
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	225	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	226	warn "timeout\n";
194	});	227	});
195		228
196	# to cancel the timer:	229	# to cancel the timer:
197	undef $w;	230	undef $w;
198		231
199	Example 2:
200
201	# 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.
202	my $w;
203		233
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	234	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		235	warn "timeout\n";
207	};	236	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		237
212	=head3 TIMING ISSUES	238	=head3 TIMING ISSUES
213		239
214	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
215	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
…		…
227	timers.	253	timers.
228		254
229	AnyEvent always prefers relative timers, if available, matching the	255	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	256	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	321	=head2 SIGNAL WATCHERS
233		322
234	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
235	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
236	be invoked whenever a signal occurs.	325	callback to be invoked whenever a signal occurs.
237		326
238	Although the callback might get passed parameters, their value and	327	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	328	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	329	callbacks cannot use arguments passed to signal watcher callbacks.
241		330
242	Multiple signal occurances can be clumped together into one callback	331	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	332	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	334	but it is guaranteed not to interrupt any other callbacks.
246		335
247	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
248	between multiple watchers.	337	between multiple watchers.
249		338
250	This watcher might use C<%SIG>, so programs overwriting those signals	339	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	346	=head2 CHILD PROCESS WATCHERS
258		347
259	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.
260		349
261	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
262	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
263	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
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	353	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	354
266	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).
267		363
268	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
269	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
270	have exited already (and no SIGCHLD will be sent anymore).	366	have exited already (and no SIGCHLD will be sent anymore).
271		367
…		…
277	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
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	374	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		375
280	Example: fork a process and wait for it	376	Example: fork a process and wait for it
281		377
282	my $done = AnyEvent->condvar;	378	my $done = AnyEvent->condvar;
283		379
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	380	my $pid = fork or exit 5;
287		381
288	my $w = AnyEvent->child (	382	my $w = AnyEvent->child (
289	pid => $pid,	383	pid => $pid,
290	cb => sub {	384	cb => sub {
291	my ($pid, $status) = @_;	385	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	386	warn "pid $pid exited with status $status";
293	$done->broadcast;	387	$done->send;
294	},	388	},
295	);	389	);
296		390
297	# do something else, then wait for process exit	391	# do something else, then wait for process exit
298	$done->wait;	392	$done->recv;
299		393
300	=head2 CONDITION VARIABLES	394	=head2 CONDITION VARIABLES
301		395
302	If you are familiar with some event loops you will know that all of them	396	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	397	require you to run some blocking "loop", "run" or similar function that
…		…
309	The instrument to do that is called a "condition variable", so called	403	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	404	because they represent a condition that must become true.
311		405
312	Condition variables can be created by calling the C<< AnyEvent->condvar	406	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	407	>> method, usually without arguments. The only argument pair allowed is
		408
314	C<cb>, which specifies a callback to be called when the condition variable	409	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	410	becomes true, with the condition variable as the first argument (but not
		411	the results).
316		412
317	After creation, the conditon variable is "false" until it becomes "true"	413	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	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).
319		417
320	Condition variables are similar to callbacks, except that you can	418	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	419	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	420	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	421	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	422	used to represent a transaction, which finishes at some point and delivers
325	a result.	423	a result.
326		424
327	Condition variables are very useful to signal that something has finished,	425	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	426	for example, if you write a module that does asynchronous http requests,
329	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
330	availability of results. The user can either act when the callback is	428	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	429	called or can synchronously C<< ->recv >> for the results.
332		430
333	You can also use them to simulate traditional event loops - for example,	431	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	432	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	433	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->broadcast >> the "quit" event.	434	button of your app, which would C<< ->send >> the "quit" event.
337		435
338	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
339	two pieces 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
340	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
341	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,
342	as this asks for trouble.	440	as this asks for trouble.
343		441
344	Condition variables are represented by hash refs in perl, and the keys	442	Condition variables are represented by hash refs in perl, and the keys
…		…
346	easy (it is often useful to build your own transaction class on top of	444	easy (it is often useful to build your own transaction class on top of
347	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	445	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	446	it's C<new> method in your own C<new> method.
349		447
350	There are two "sides" to a condition variable - the "producer side" which	448	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	449	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	450	for the send to occur.
353		451
354	Example:	452	Example: wait for a timer.
355		453
356	# wait till the result is ready	454	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	455	my $result_ready = AnyEvent->condvar;
358		456
359	# do something such as adding a timer	457	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	458	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	459	# when the "result" is ready.
362	# in this case, we simply use a timer:	460	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	461	my $w = AnyEvent->timer (
364	after => 1,	462	after => 1,
365	cb => sub { $result_ready->broadcast },	463	cb => sub { $result_ready->send },
366	);	464	);
367		465
368	# this "blocks" (while handling events) till the callback	466	# this "blocks" (while handling events) till the callback
369	# calls broadcast	467	# calls send
370	$result_ready->wait;	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	});
371		493
372	=head3 METHODS FOR PRODUCERS	494	=head3 METHODS FOR PRODUCERS
373		495
374	These methods should only be used by the producing side, i.e. the	496	These methods should only be used by the producing side, i.e. the
375	code/module that eventually broadcasts the signal. Note that it is also	497	code/module that eventually sends the signal. Note that it is also
376	the producer side which creates the condvar in most cases, but it isn't	498	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	499	uncommon for the consumer to create it as well.
378		500
379	=over 4	501	=over 4
380		502
381	=item $cv->broadcast (...)	503	=item $cv->send (...)
382		504
383	Flag the condition as ready - a running C<< ->wait >> and all further	505	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	506	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	507	called. If nobody is waiting the send will be remembered.
386		508
387	If a callback has been set on the condition variable, it is called	509	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	510	immediately from within send.
389		511
390	Any arguments passed to the C<broadcast> call will be returned by all	512	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	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).
392		523
393	=item $cv->croak ($error)	524	=item $cv->croak ($error)
394		525
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	526	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	527	C<Carp::croak> with the given error message/object/scalar.
397		528
398	This can be used to signal any errors to the condition variable	529	This can be used to signal any errors to the condition variable
399	user/consumer.	530	user/consumer.
400		531
401	=item $cv->begin ([group callback])	532	=item $cv->begin ([group callback])
402		533
403	=item $cv->end	534	=item $cv->end
		535
		536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		537
405	These two methods can be used to combine many transactions/events into	538	These two methods can be used to combine many transactions/events into
406	one. For example, a function that pings many hosts in parallel might want	539	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	540	to use a condition variable for the whole process.
408		541
409	Every call to C<< ->begin >> will increment a counter, and every call to	542	Every call to C<< ->begin >> will increment a counter, and every call to
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	543	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	544	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->broadcast >>, but that is not required. If no	545	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<broadcast> will be called without any arguments.	546	callback was set, C<send> will be called without any arguments.
414		547
415	Let's clarify this with the ping example:	548	Let's clarify this with the ping example:
416		549
417	my $cv = AnyEvent->condvar;	550	my $cv = AnyEvent->condvar;
418		551
419	my %result;	552	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	553	$cv->begin (sub { $cv->send (\%result) });
421		554
422	for my $host (@list_of_hosts) {	555	for my $host (@list_of_hosts) {
423	$cv->begin;	556	$cv->begin;
424	ping_host_then_call_callback $host, sub {	557	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	558	$result{$host} = ...;
…		…
428	}	561	}
429		562
430	$cv->end;	563	$cv->end;
431		564
432	This code fragment supposedly pings a number of hosts and calls	565	This code fragment supposedly pings a number of hosts and calls
433	C<broadcast> after results for all then have have been gathered - in any	566	C<send> after results for all then have have been gathered - in any
434	order. To achieve this, the code issues a call to C<begin> when it starts	567	order. To achieve this, the code issues a call to C<begin> when it starts
435	each ping request and calls C<end> when it has received some result for	568	each ping request and calls C<end> when it has received some result for
436	it. Since C<begin> and C<end> only maintain a counter, the order in which	569	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	570	results arrive is not relevant.
438		571
439	There is an additional bracketing call to C<begin> and C<end> outside the	572	There is an additional bracketing call to C<begin> and C<end> outside the
440	loop, which serves two important purposes: first, it sets the callback	573	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	574	to be called once the counter reaches C<0>, and second, it ensures that
442	broadcast is called even when C<no> hosts are being pinged (the loop	575	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	576	doesn't execute once).
444		577
445	This is the general pattern when you "fan out" into multiple subrequests:	578	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	579	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	580	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	581	C<begin> and for each subrequest you finish, call C<end>.
449		582
450	=back	583	=back
451		584
452	=head3 METHODS FOR CONSUMERS	585	=head3 METHODS FOR CONSUMERS
453		586
454	These methods should only be used by the consuming side, i.e. the	587	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	588	code awaits the condition.
456		589
457	=item $cv->wait	590	=over 4
458		591
		592	=item $cv->recv
		593
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	594	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	595	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	596	normally.
462		597
463	You can only wait once on a condition - additional calls are valid but	598	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	599	will return immediately.
465		600
466	If an error condition has been set by calling C<< ->croak >>, then this	601	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	602	function will call C<croak>.
468		603
469	In list context, all parameters passed to C<broadcast> will be returned,	604	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	605	in scalar context only the first one will be returned.
471		606
472	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
473	(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
474	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
475	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
476	condition variables with some kind of request results and supporting	611	condition variables with some kind of request results and supporting
477	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,
478	while still suppporting blocking waits if the caller so desires).	613	while still supporting blocking waits if the caller so desires).
479		614
480	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
481	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
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	618	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		619
		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).
		625
487	You can ensure that C<< -wait >> never blocks by setting a callback and	626	You can ensure that C<< -recv >> never blocks by setting a callback and
488	only calling C<< ->wait >> from within that callback (or at a later	627	only calling C<< ->recv >> from within that callback (or at a later
489	time). This will work even when the event loop does not support blocking	628	time). This will work even when the event loop does not support blocking
490	waits otherwise.	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->($cv))
		637
		638	This is a mutator function that returns the callback set and optionally
		639	replaces it before doing so.
		640
		641	The callback will be called when the condition becomes "true", i.e. when
		642	C<send> or C<croak> are called, with the only argument being the condition
		643	variable itself. Calling C<recv> inside the callback or at any later time
		644	is guaranteed not to block.
491		645
492	=back	646	=back
493		647
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	648	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		649
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		659
506	The known classes so far are:	660	The known classes so far are:
507		661
508	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	663	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	665	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	666	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	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
533	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
534	runtime.	686	runtime.
535		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
536	=back	709	=back
537		710
538	=head1 WHAT TO DO IN A MODULE	711	=head1 WHAT TO DO IN A MODULE
539		712
540	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
…		…
543	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
544	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
545	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
546	to load the event module first.	719	to load the event module first.
547		720
548	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
549	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
550	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
551	events is to stay interactive.	724	events is to stay interactive.
552		725
553	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
554	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
555	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 >>
556	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).
557		730
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	731	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		732
560	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
…		…
562		735
563	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
564	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
565	decide which implementation to chose if some module relies on it.	738	decide which implementation to chose if some module relies on it.
566		739
567	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
568	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
569	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
570	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
571	modules might create watchers when they are loaded, and AnyEvent will	744	modules might create watchers when they are loaded, and AnyEvent will
572	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
573	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.
574		747
575	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
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	749	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	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
578		768
579	=head1 OTHER MODULES	769	=head1 OTHER MODULES
580		770
581	The following is a non-exhaustive list of additional modules that use	771	The following is a non-exhaustive list of additional modules that use
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	772	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
588	=item L<AnyEvent::Util>	778	=item L<AnyEvent::Util>
589		779
590	Contains various utility functions that replace often-used but blocking	780	Contains various utility functions that replace often-used but blocking
591	functions such as C<inet_aton> by event-/callback-based versions.	781	functions such as C<inet_aton> by event-/callback-based versions.
592		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
593	=item L<AnyEvent::Handle>	789	=item L<AnyEvent::Handle>
594		790
595	Provide read and write buffers and manages watchers for reads and writes.	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.
596		794
597	=item L<AnyEvent::Socket>	795	=item L<AnyEvent::DNS>
598		796
599	Provides a means to do non-blocking connects, accepts etc.	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.
600		803
601	=item L<AnyEvent::HTTPD>	804	=item L<AnyEvent::HTTPD>
602		805
603	Provides a simple web application server framework.	806	Provides a simple web application server framework.
604		807
605	=item L<AnyEvent::DNS>
606
607	Provides asynchronous DNS resolver capabilities, beyond what
608	L<AnyEvent::Util> offers.
609
610	=item L<AnyEvent::FastPing>	808	=item L<AnyEvent::FastPing>
611		809
612	The fastest ping in the west.	810	The fastest ping in the west.
613		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
614	=item L<Net::IRC3>	836	=item L<AnyEvent::IRC>
615		837
616	AnyEvent based IRC client module family.	838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
617		839
618	=item L<Net::XMPP2>	840	=item L<Net::XMPP2>
619		841
620	AnyEvent based XMPP (Jabber protocol) module family.	842	AnyEvent based XMPP (Jabber protocol) module family.
621		843
…		…
628		850
629	High level API for event-based execution flow control.	851	High level API for event-based execution flow control.
630		852
631	=item L<Coro>	853	=item L<Coro>
632		854
633	Has special support for AnyEvent.	855	Has special support for AnyEvent via L<Coro::AnyEvent>.
634		856
635	=item L<IO::Lambda>	857	=item L<IO::Lambda>
636		858
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638		860
639	=item L<IO::AIO>
640
641	Truly asynchronous I/O, should be in the toolbox of every event
642	programmer. Can be trivially made to use AnyEvent.
643
644	=item L<BDB>
645
646	Truly asynchronous Berkeley DB access. Can be trivially made to use
647	AnyEvent.
648
649	=back	861	=back
650		862
651	=cut	863	=cut
652		864
653	package AnyEvent;	865	package AnyEvent;
654		866
655	no warnings;	867	no warnings;
656	use strict;	868	use strict qw(vars subs);
657		869
658	use Carp;	870	use Carp;
659		871
660	our $VERSION = '3.3';	872	our $VERSION = 4.341;
661	our $MODEL;	873	our $MODEL;
662		874
663	our $AUTOLOAD;	875	our $AUTOLOAD;
664	our @ISA;	876	our @ISA;
665		877
		878	our @REGISTRY;
		879
		880	our $WIN32;
		881
		882	BEGIN {
		883	my $win32 = ! ! ($^O =~ /mswin32/i);
		884	eval "sub WIN32(){ $win32 }";
		885	}
		886
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		888
668	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	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		896	}
669		897
670	my @models = (	898	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	899	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	900	[Event:: => AnyEvent::Impl::Event::],
675	[Tk:: => AnyEvent::Impl::Tk::],
676	[Wx:: => AnyEvent::Impl::POE::],
677	[Prima:: => AnyEvent::Impl::POE::],
678	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	902	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	903	# as the pureperl backend should work everywhere
		904	# and is usually faster
		905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		910	[Wx:: => AnyEvent::Impl::POE::],
		911	[Prima:: => AnyEvent::Impl::POE::],
684	);	912	);
685		913
686	our %method = map +($_ => 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	}
687		937
688	sub detect() {	938	sub detect() {
689	unless ($MODEL) {	939	unless ($MODEL) {
690	no strict 'refs';	940	no strict 'refs';
		941	local $SIG{__DIE__};
691		942
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	944	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	945	if (eval "require $model") {
695	$MODEL = $model;	946	$MODEL = $model;
…		…
725	last;	976	last;
726	}	977	}
727	}	978	}
728		979
729	$MODEL	980	$MODEL
730	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
731	}	982	}
732	}	983	}
733		984
		985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		986
734	unshift @ISA, $MODEL;	987	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	988
		989	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		990
		991	(shift @post_detect)->() while @post_detect;
736	}	992	}
737		993
738	$MODEL	994	$MODEL
739	}	995	}
740		996
…		…
748		1004
749	my $class = shift;	1005	my $class = shift;
750	$class->$func (@_);	1006	$class->$func (@_);
751	}	1007	}
752		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
753	package AnyEvent::Base;	1028	package AnyEvent::Base;
754		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
755	# default implementation for ->condvar, ->wait, ->broadcast	1044	# default implementation for ->condvar
756		1045
757	sub condvar {	1046	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
759	}
760
761	sub AnyEvent::Base::CondVar::broadcast {
762	${$_[0]}++;
763	}
764
765	sub AnyEvent::Base::CondVar::wait {
766	AnyEvent->one_event while !${$_[0]};
767	}	1048	}
768		1049
769	# default implementation for ->signal	1050	# default implementation for ->signal
770		1051
771	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	}
772		1063
773	sub signal {	1064	sub signal {
774	my (undef, %arg) = @_;	1065	my (undef, %arg) = @_;
775		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
776	my $signal = uc $arg{signal}	1085	my $signal = uc $arg{signal}
777	or Carp::croak "required option 'signal' is missing";	1086	or Carp::croak "required option 'signal' is missing";
778		1087
779	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1088	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
780	$SIG{$signal} ||= sub {	1089	$SIG{$signal} ||= sub {
781	$_->() for values %{ $SIG_CB{$signal} || {} };	1090	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1091	undef $SIG_EV{$signal};
782	};	1092	};
783		1093
784	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1094	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
785	}	1095	}
786		1096
787	sub AnyEvent::Base::Signal::DESTROY {	1097	sub AnyEvent::Base::Signal::DESTROY {
788	my ($signal, $cb) = @{$_[0]};	1098	my ($signal, $cb) = @{$_[0]};
789		1099
790	delete $SIG_CB{$signal}{$cb};	1100	delete $SIG_CB{$signal}{$cb};
791		1101
792	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1102	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
793	}	1103	}
794		1104
795	# default implementation for ->child	1105	# default implementation for ->child
796		1106
797	our %PID_CB;	1107	our %PID_CB;
…		…
824	or Carp::croak "required option 'pid' is missing";	1134	or Carp::croak "required option 'pid' is missing";
825		1135
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1136	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1137
828	unless ($WNOHANG) {	1138	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1139	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
830	}	1140	}
831		1141
832	unless ($CHLD_W) {	1142	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1143	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# 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
…		…
844	delete $PID_CB{$pid}{$cb};	1154	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1155	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1156
847	undef $CHLD_W unless keys %PID_CB;	1157	undef $CHLD_W unless keys %PID_CB;
848	}	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
849		1325
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1326	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1327
852	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
853	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
…		…
887		1363
888	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
889	condition variables: code blocking while waiting for a condition will	1365	condition variables: code blocking while waiting for a condition will
890	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
891	not be done in an interactive application, so it makes sense.	1367	not be done in an interactive application, so it makes sense.
892
893	=head1 ENVIRONMENT VARIABLES
894
895	The following environment variables are used by this module:
896
897	=over 4
898
899	=item C<PERL_ANYEVENT_VERBOSE>
900
901	By default, AnyEvent will be completely silent except in fatal
902	conditions. You can set this environment variable to make AnyEvent more
903	talkative.
904
905	When set to C<1> or higher, causes AnyEvent to warn about unexpected
906	conditions, such as not being able to load the event model specified by
907	C<PERL_ANYEVENT_MODEL>.
908
909	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
910	model it chooses.
911
912	=item C<PERL_ANYEVENT_MODEL>
913
914	This can be used to specify the event model to be used by AnyEvent, before
915	autodetection and -probing kicks in. It must be a string consisting
916	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
917	and the resulting module name is loaded and if the load was successful,
918	used as event model. If it fails to load AnyEvent will proceed with
919	autodetection and -probing.
920
921	This functionality might change in future versions.
922
923	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
924	could start your program like this:
925
926	PERL_ANYEVENT_MODEL=Perl perl ...
927
928	=back
929		1368
930	=head1 EXAMPLE PROGRAM	1369	=head1 EXAMPLE PROGRAM
931		1370
932	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
933	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
…		…
942	poll => 'r',	1381	poll => 'r',
943	cb => sub {	1382	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1383	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1384	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1385	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1386	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1387	},
949	);	1388	);
950		1389
951	my $time_watcher; # can only be used once	1390	my $time_watcher; # can only be used once
952		1391
…		…
957	});	1396	});
958	}	1397	}
959		1398
960	new_timer; # create first timer	1399	new_timer; # create first timer
961		1400
962	$cv->wait; # wait until user enters /^q/i	1401	$cv->recv; # wait until user enters /^q/i
963		1402
964	=head1 REAL-WORLD EXAMPLE	1403	=head1 REAL-WORLD EXAMPLE
965		1404
966	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
967	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:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1456	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1457	or die "connection or write error";
1019	$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 });
1020		1459
1021	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
1022	result and signals any possible waiters that the request ahs finished:	1461	result and signals any possible waiters that the request has finished:
1023		1462
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1463	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1464
1026	if (end-of-file or data complete) {	1465	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1466	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1467	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1468	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1469	}
1031		1470
1032	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
1033	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
1034	data:	1473	data:
1035		1474
1036	$txn->{finished}->wait;	1475	$txn->{finished}->recv;
1037	return $txn->{result};	1476	return $txn->{result};
1038		1477
1039	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)
1040	that occured during request processing. The C<result> method detects	1479	that occurred during request processing. The C<result> method detects
1041	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)
1042	and just throws the exception, which means connection errors and other	1481	and just throws the exception, which means connection errors and other
1043	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
1044	random callback.	1483	random callback.
1045		1484
…		…
1076		1515
1077	my $quit = AnyEvent->condvar;	1516	my $quit = AnyEvent->condvar;
1078		1517
1079	$fcp->txn_client_get ($url)->cb (sub {	1518	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1519	...
1081	$quit->broadcast;	1520	$quit->send;
1082	});	1521	});
1083		1522
1084	$quit->wait;	1523	$quit->recv;
1085		1524
1086		1525
1087	=head1 BENCHMARKS	1526	=head1 BENCHMARKS
1088		1527
1089	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
…		…
1091	of various event loops I prepared some benchmarks.	1530	of various event loops I prepared some benchmarks.
1092		1531
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1532	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1533
1095	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
1096	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
1097	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,
1098	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.
1099		1538
1100	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
1101	distribution.	1540	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1557	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1558	and memory usage is not included in the figures.
1120		1559
1121	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
1122	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
1123	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1562	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1563	signal the end of this phase.
1125		1564
1126	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
1127	watcher.	1566	watcher.
1128		1567
1129	=head3 Results	1568	=head3 Results
1130		1569
1131	name watchers bytes create invoke destroy comment	1570	name watchers bytes create invoke destroy comment
1132	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
1133	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
1134	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
1135	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
1136	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
1137	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1576	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1138	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
1139	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
1140	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
1141	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
1142		1581
1143	=head3 Discussion	1582	=head3 Discussion
1144		1583
1145	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
1146	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)
…		…
1224		1663
1225	=back	1664	=back
1226		1665
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1666	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1667
1229	This benchmark atcually benchmarks the event loop itself. It works by	1668	This benchmark actually benchmarks the event loop itself. It works by
1230	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
1231	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
1232	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
1233	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".
1234		1673
1235	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
1236	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
1237	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
1238	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
1239	most timeouts work (and puts extra pressure on the event loops).	1678	most timeouts work (and puts extra pressure on the event loops).
1240		1679
1241	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
1242	(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
1243	connections, most of which are idle at any one point in time.	1682	connections, most of which are idle at any one point in time.
1244		1683
1245	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
1246	distribution.	1685	distribution.
…		…
1248	=head3 Explanation of the columns	1687	=head3 Explanation of the columns
1249		1688
1250	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
1251	each server has a read and write socket end).	1690	each server has a read and write socket end).
1252		1691
1253	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
1254	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.
1255		1694
1256	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
1257	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
1258	it to another server. This includes deleting the old timeout and creating	1697	it to another server. This includes deleting the old timeout and creating
…		…
1331	speed most when you have lots of watchers, not when you only have a few of	1770	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1771	them).
1333		1772
1334	EV is again fastest.	1773	EV is again fastest.
1335		1774
1336	Perl again comes second. It is noticably faster than the C-based event	1775	Perl again comes second. It is noticeably faster than the C-based event
1337	loops Event and Glib, although the difference is too small to really	1776	loops Event and Glib, although the difference is too small to really
1338	matter.	1777	matter.
1339		1778
1340	POE also performs much better in this case, but is is still far behind the	1779	POE also performs much better in this case, but is is still far behind the
1341	others.	1780	others.
…		…
1346		1785
1347	=item * C-based event loops perform very well with small number of	1786	=item * C-based event loops perform very well with small number of
1348	watchers, as the management overhead dominates.	1787	watchers, as the management overhead dominates.
1349		1788
1350	=back	1789	=back
		1790
		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};
1351		1826
1352		1827
1353	=head1 FORK	1828	=head1 FORK
1354		1829
1355	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
…		…
1370	specified in the variable.	1845	specified in the variable.
1371		1846
1372	You can make AnyEvent completely ignore this variable by deleting it	1847	You can make AnyEvent completely ignore this variable by deleting it
1373	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:
1374		1849
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1850	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		1851
1377	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).
1378		1867
1379		1868
1380	=head1 SEE ALSO	1869	=head1 SEE ALSO
1381		1870
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1871	Utility functions: L<AnyEvent::Util>.
1383	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>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	1874	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		1875
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1876	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	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>,
1388	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1878	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1879	L<AnyEvent::Impl::POE>.
1390		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
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1888	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		1889
1393		1890
1394	=head1 AUTHOR	1891	=head1 AUTHOR
1395		1892
1396	Marc Lehmann <schmorp@schmorp.de>	1893	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	1894	http://home.schmorp.de/
1398		1895
1399	=cut	1896	=cut
1400		1897
1401	1	1898	1
1402		1899

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