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Revision 1.200 by root, Wed Apr 1 14:02:27 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> is the Perl I<file handle> (I<not> file descriptor) to watch
		174	for events (AnyEvent might or might not keep a reference to this file
		175	handle). Note that only file handles pointing to things for which
		176	non-blocking operation makes sense are allowed. This includes sockets,
		177	most character devices, pipes, fifos and so on, but not for example files
		178	or block devices.
		179
146	for events. C<poll> must be a string that is either C<r> or C<w>,	180	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
148	respectively. C<cb> is the callback to invoke each time the file handle	183	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		184
151	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
154		188
…		…
158		192
159	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	194	always use non-blocking calls when reading/writing from/to your file
161	handles.	195	handles.
162		196
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	197	Example: wait for readability of STDIN, then read a line and disable the
		198	watcher.
		199
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	202	warn "read: $input\n";
169	undef $w;	203	undef $w;
170	});	204	});
…		…
180		214
181	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
184		218
185	The timer callback will be invoked at most once: if you want a repeating	219	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	220	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	221	callback will be invoked regularly at that interval (in fractional
		222	seconds) after the first invocation. If C<interval> is specified with a
		223	false value, then it is treated as if it were missing.
188		224
189	Example:	225	The callback will be rescheduled before invoking the callback, but no
		226	attempt is done to avoid timer drift in most backends, so the interval is
		227	only approximate.
190		228
191	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	232	warn "timeout\n";
194	});	233	});
195		234
196	# to cancel the timer:	235	# to cancel the timer:
197	undef $w;	236	undef $w;
198		237
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	238	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		239
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
207	};	242	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		243
212	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
213		245
214	There are two ways to handle timers: based on real time (relative, "fire	246	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	247	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	259	timers.
228		260
229	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	262	AnyEvent API.
231		263
		264	AnyEvent has two additional methods that return the "current time":
		265
		266	=over 4
		267
		268	=item AnyEvent->time
		269
		270	This returns the "current wallclock time" as a fractional number of
		271	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		272	return, and the result is guaranteed to be compatible with those).
		273
		274	It progresses independently of any event loop processing, i.e. each call
		275	will check the system clock, which usually gets updated frequently.
		276
		277	=item AnyEvent->now
		278
		279	This also returns the "current wallclock time", but unlike C<time>, above,
		280	this value might change only once per event loop iteration, depending on
		281	the event loop (most return the same time as C<time>, above). This is the
		282	time that AnyEvent's timers get scheduled against.
		283
		284	I<In almost all cases (in all cases if you don't care), this is the
		285	function to call when you want to know the current time.>
		286
		287	This function is also often faster then C<< AnyEvent->time >>, and
		288	thus the preferred method if you want some timestamp (for example,
		289	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		290
		291	The rest of this section is only of relevance if you try to be very exact
		292	with your timing, you can skip it without bad conscience.
		293
		294	For a practical example of when these times differ, consider L<Event::Lib>
		295	and L<EV> and the following set-up:
		296
		297	The event loop is running and has just invoked one of your callback at
		298	time=500 (assume no other callbacks delay processing). In your callback,
		299	you wait a second by executing C<sleep 1> (blocking the process for a
		300	second) and then (at time=501) you create a relative timer that fires
		301	after three seconds.
		302
		303	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		304	both return C<501>, because that is the current time, and the timer will
		305	be scheduled to fire at time=504 (C<501> + C<3>).
		306
		307	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		308	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		309	last event processing phase started. With L<EV>, your timer gets scheduled
		310	to run at time=503 (C<500> + C<3>).
		311
		312	In one sense, L<Event::Lib> is more exact, as it uses the current time
		313	regardless of any delays introduced by event processing. However, most
		314	callbacks do not expect large delays in processing, so this causes a
		315	higher drift (and a lot more system calls to get the current time).
		316
		317	In another sense, L<EV> is more exact, as your timer will be scheduled at
		318	the same time, regardless of how long event processing actually took.
		319
		320	In either case, if you care (and in most cases, you don't), then you
		321	can get whatever behaviour you want with any event loop, by taking the
		322	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		323	account.
		324
		325	=back
		326
232	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
233		328
234	You can watch for signals using a signal watcher, C<signal> is the signal	329	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	330	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
237		332
238	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
241		336
242	Multiple signal occurances can be clumped together into one callback	337	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	338	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	339	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.	340	but it is guaranteed not to interrupt any other callbacks.
246		341
247	The main advantage of using these watchers is that you can share a signal	342	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	343	between multiple watchers.
249		344
250	This watcher might use C<%SIG>, so programs overwriting those signals	345	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
258		353
259	You can also watch on a child process exit and catch its exit status.	354	You can also watch on a child process exit and catch its exit status.
260		355
261	The child process is specified by the C<pid> argument (if set to C<0>, it	356	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	357	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	358	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	359	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	360
266	you I<can> rely on child watcher callback arguments.	361	The callback will be called with the pid and exit status (as returned by
		362	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		363	callback arguments.
		364
		365	This watcher type works by installing a signal handler for C<SIGCHLD>,
		366	and since it cannot be shared, nothing else should use SIGCHLD or reap
		367	random child processes (waiting for specific child processes, e.g. inside
		368	C<system>, is just fine).
267		369
268	There is a slight catch to child watchers, however: you usually start them	370	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	371	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
271		373
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	379	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>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		381
280	Example: fork a process and wait for it	382	Example: fork a process and wait for it
281		383
282	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
283		385
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
287		387
288	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
289	pid => $pid,	389	pid => $pid,
290	cb => sub {	390	cb => sub {
291	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
293	$done->broadcast;	393	$done->send;
294	},	394	},
295	);	395	);
296		396
297	# do something else, then wait for process exit	397	# do something else, then wait for process exit
298	$done->wait;	398	$done->recv;
299		399
300	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
301		401
302	If you are familiar with some event loops you will know that all of them	402	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	403	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	409	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	410	because they represent a condition that must become true.
311		411
312	Condition variables can be created by calling the C<< AnyEvent->condvar	412	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	413	>> method, usually without arguments. The only argument pair allowed is
		414
314	C<cb>, which specifies a callback to be called when the condition variable	415	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
316		418
317	After creation, the conditon variable is "false" until it becomes "true"	419	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	420	by calling the C<send> method (or calling the condition variable as if it
		421	were a callback, read about the caveats in the description for the C<<
		422	->send >> method).
319		423
320	Condition variables are similar to callbacks, except that you can	424	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	425	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	426	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	427	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	428	used to represent a transaction, which finishes at some point and delivers
325	a result.	429	a result.
326		430
327	Condition variables are very useful to signal that something has finished,	431	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	432	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	433	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	434	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	435	called or can synchronously C<< ->recv >> for the results.
332		436
333	You can also use them to simulate traditional event loops - for example,	437	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	438	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	439	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.	440	button of your app, which would C<< ->send >> the "quit" event.
337		441
338	Note that condition variables recurse into the event loop - if you have	442	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	443	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	444	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,	445	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	446	as this asks for trouble.
343		447
344	Condition variables are represented by hash refs in perl, and the keys	448	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	450	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	451	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	452	it's C<new> method in your own C<new> method.
349		453
350	There are two "sides" to a condition variable - the "producer side" which	454	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	455	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	456	for the send to occur.
353		457
354	Example:	458	Example: wait for a timer.
355		459
356	# wait till the result is ready	460	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	461	my $result_ready = AnyEvent->condvar;
358		462
359	# do something such as adding a timer	463	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	464	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	465	# when the "result" is ready.
362	# in this case, we simply use a timer:	466	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	467	my $w = AnyEvent->timer (
364	after => 1,	468	after => 1,
365	cb => sub { $result_ready->broadcast },	469	cb => sub { $result_ready->send },
366	);	470	);
367		471
368	# this "blocks" (while handling events) till the callback	472	# this "blocks" (while handling events) till the callback
369	# calls broadcast	473	# calls send
370	$result_ready->wait;	474	$result_ready->recv;
		475
		476	Example: wait for a timer, but take advantage of the fact that
		477	condition variables are also code references.
		478
		479	my $done = AnyEvent->condvar;
		480	my $delay = AnyEvent->timer (after => 5, cb => $done);
		481	$done->recv;
		482
		483	Example: Imagine an API that returns a condvar and doesn't support
		484	callbacks. This is how you make a synchronous call, for example from
		485	the main program:
		486
		487	use AnyEvent::CouchDB;
		488
		489	...
		490
		491	my @info = $couchdb->info->recv;
		492
		493	And this is how you would just ste a callback to be called whenever the
		494	results are available:
		495
		496	$couchdb->info->cb (sub {
		497	my @info = $_[0]->recv;
		498	});
371		499
372	=head3 METHODS FOR PRODUCERS	500	=head3 METHODS FOR PRODUCERS
373		501
374	These methods should only be used by the producing side, i.e. the	502	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	503	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	504	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	505	uncommon for the consumer to create it as well.
378		506
379	=over 4	507	=over 4
380		508
381	=item $cv->broadcast (...)	509	=item $cv->send (...)
382		510
383	Flag the condition as ready - a running C<< ->wait >> and all further	511	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	512	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	513	called. If nobody is waiting the send will be remembered.
386		514
387	If a callback has been set on the condition variable, it is called	515	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	516	immediately from within send.
389		517
390	Any arguments passed to the C<broadcast> call will be returned by all	518	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	519	future C<< ->recv >> calls.
		520
		521	Condition variables are overloaded so one can call them directly
		522	(as a code reference). Calling them directly is the same as calling
		523	C<send>. Note, however, that many C-based event loops do not handle
		524	overloading, so as tempting as it may be, passing a condition variable
		525	instead of a callback does not work. Both the pure perl and EV loops
		526	support overloading, however, as well as all functions that use perl to
		527	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		528	example).
392		529
393	=item $cv->croak ($error)	530	=item $cv->croak ($error)
394		531
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	532	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	533	C<Carp::croak> with the given error message/object/scalar.
397		534
398	This can be used to signal any errors to the condition variable	535	This can be used to signal any errors to the condition variable
399	user/consumer.	536	user/consumer.
400		537
401	=item $cv->begin ([group callback])	538	=item $cv->begin ([group callback])
402		539
403	=item $cv->end	540	=item $cv->end
		541
		542	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		543
405	These two methods can be used to combine many transactions/events into	544	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	545	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	546	to use a condition variable for the whole process.
408		547
409	Every call to C<< ->begin >> will increment a counter, and every call to	548	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	549	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	550	>>, 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	551	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.	552	callback was set, C<send> will be called without any arguments.
414		553
415	Let's clarify this with the ping example:	554	Let's clarify this with the ping example:
416		555
417	my $cv = AnyEvent->condvar;	556	my $cv = AnyEvent->condvar;
418		557
419	my %result;	558	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	559	$cv->begin (sub { $cv->send (\%result) });
421		560
422	for my $host (@list_of_hosts) {	561	for my $host (@list_of_hosts) {
423	$cv->begin;	562	$cv->begin;
424	ping_host_then_call_callback $host, sub {	563	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	564	$result{$host} = ...;
…		…
428	}	567	}
429		568
430	$cv->end;	569	$cv->end;
431		570
432	This code fragment supposedly pings a number of hosts and calls	571	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	572	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	573	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	574	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	575	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	576	results arrive is not relevant.
438		577
439	There is an additional bracketing call to C<begin> and C<end> outside the	578	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	579	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	580	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	581	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	582	doesn't execute once).
444		583
445	This is the general pattern when you "fan out" into multiple subrequests:	584	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>	585	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	586	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>.	587	C<begin> and for each subrequest you finish, call C<end>.
449		588
450	=back	589	=back
451		590
452	=head3 METHODS FOR CONSUMERS	591	=head3 METHODS FOR CONSUMERS
453		592
454	These methods should only be used by the consuming side, i.e. the	593	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	594	code awaits the condition.
456		595
457	=item $cv->wait	596	=over 4
458		597
		598	=item $cv->recv
		599
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	600	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	601	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	602	normally.
462		603
463	You can only wait once on a condition - additional calls are valid but	604	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	605	will return immediately.
465		606
466	If an error condition has been set by calling C<< ->croak >>, then this	607	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	608	function will call C<croak>.
468		609
469	In list context, all parameters passed to C<broadcast> will be returned,	610	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	611	in scalar context only the first one will be returned.
471		612
472	Not all event models support a blocking wait - some die in that case	613	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	614	(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	615	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	616	caller decide whether the call will block or not (for example, by coupling
476	condition variables with some kind of request results and supporting	617	condition variables with some kind of request results and supporting
477	callbacks so the caller knows that getting the result will not block,	618	callbacks so the caller knows that getting the result will not block,
478	while still suppporting blocking waits if the caller so desires).	619	while still supporting blocking waits if the caller so desires).
479		620
480	Another reason I<never> to C<< ->wait >> in a module is that you cannot	621	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	622	sensibly have two C<< ->recv >>'s in parallel, as that would require
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	623	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	624	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		625
		626	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		627	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		628	versions and also integrates coroutines into AnyEvent, making blocking
		629	C<< ->recv >> calls perfectly safe as long as they are done from another
		630	coroutine (one that doesn't run the event loop).
		631
487	You can ensure that C<< -wait >> never blocks by setting a callback and	632	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	633	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	634	time). This will work even when the event loop does not support blocking
490	waits otherwise.	635	waits otherwise.
		636
		637	=item $bool = $cv->ready
		638
		639	Returns true when the condition is "true", i.e. whether C<send> or
		640	C<croak> have been called.
		641
		642	=item $cb = $cv->cb ($cb->($cv))
		643
		644	This is a mutator function that returns the callback set and optionally
		645	replaces it before doing so.
		646
		647	The callback will be called when the condition becomes "true", i.e. when
		648	C<send> or C<croak> are called, with the only argument being the condition
		649	variable itself. Calling C<recv> inside the callback or at any later time
		650	is guaranteed not to block.
491		651
492	=back	652	=back
493		653
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		655
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	663	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	664	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		665
506	The known classes so far are:	666	The known classes so far are:
507		667
508	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	668	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	669	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	670	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	671	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	672	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	689	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	if necessary. You should only call this function right before you would	690	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	691	have created an AnyEvent watcher anyway, that is, as late as possible at
534	runtime.	692	runtime.
535		693
		694	=item $guard = AnyEvent::post_detect { BLOCK }
		695
		696	Arranges for the code block to be executed as soon as the event model is
		697	autodetected (or immediately if this has already happened).
		698
		699	If called in scalar or list context, then it creates and returns an object
		700	that automatically removes the callback again when it is destroyed. See
		701	L<Coro::BDB> for a case where this is useful.
		702
		703	=item @AnyEvent::post_detect
		704
		705	If there are any code references in this array (you can C<push> to it
		706	before or after loading AnyEvent), then they will called directly after
		707	the event loop has been chosen.
		708
		709	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		710	if it contains a true value then the event loop has already been detected,
		711	and the array will be ignored.
		712
		713	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		714
536	=back	715	=back
537		716
538	=head1 WHAT TO DO IN A MODULE	717	=head1 WHAT TO DO IN A MODULE
539		718
540	As a module author, you should C<use AnyEvent> and call AnyEvent methods	719	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	722	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	723	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	724	by calling AnyEvent in your module body you force the user of your module
546	to load the event module first.	725	to load the event module first.
547		726
548	Never call C<< ->wait >> on a condition variable unless you I<know> that	727	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	728	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	729	because it will stall the whole program, and the whole point of using
551	events is to stay interactive.	730	events is to stay interactive.
552		731
553	It is fine, however, to call C<< ->wait >> when the user of your module	732	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	733	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 >>	734	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).	735	freely, as the user of your module knows what she is doing. always).
557		736
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	737	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		738
560	There will always be a single main program - the only place that should	739	There will always be a single main program - the only place that should
…		…
562		741
563	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	742	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	743	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.	744	decide which implementation to chose if some module relies on it.
566		745
567	If the main program relies on a specific event model. For example, in	746	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	747	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	748	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	749	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	750	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	751	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.	752	might chose the wrong one unless you load the correct one yourself.
574		753
575	You can chose to use a rather inefficient pure-perl implementation by	754	You can chose to use a pure-perl implementation by loading the
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	behaviour everywhere, but letting AnyEvent chose is generally better.	756	everywhere, but letting AnyEvent chose the model is generally better.
		757
		758	=head2 MAINLOOP EMULATION
		759
		760	Sometimes (often for short test scripts, or even standalone programs who
		761	only want to use AnyEvent), you do not want to run a specific event loop.
		762
		763	In that case, you can use a condition variable like this:
		764
		765	AnyEvent->condvar->recv;
		766
		767	This has the effect of entering the event loop and looping forever.
		768
		769	Note that usually your program has some exit condition, in which case
		770	it is better to use the "traditional" approach of storing a condition
		771	variable somewhere, waiting for it, and sending it when the program should
		772	exit cleanly.
		773
578		774
579	=head1 OTHER MODULES	775	=head1 OTHER MODULES
580		776
581	The following is a non-exhaustive list of additional modules that use	777	The following is a non-exhaustive list of additional modules that use
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
588	=item L<AnyEvent::Util>	784	=item L<AnyEvent::Util>
589		785
590	Contains various utility functions that replace often-used but blocking	786	Contains various utility functions that replace often-used but blocking
591	functions such as C<inet_aton> by event-/callback-based versions.	787	functions such as C<inet_aton> by event-/callback-based versions.
592		788
		789	=item L<AnyEvent::Socket>
		790
		791	Provides various utility functions for (internet protocol) sockets,
		792	addresses and name resolution. Also functions to create non-blocking tcp
		793	connections or tcp servers, with IPv6 and SRV record support and more.
		794
593	=item L<AnyEvent::Handle>	795	=item L<AnyEvent::Handle>
594		796
595	Provide read and write buffers and manages watchers for reads and writes.	797	Provide read and write buffers, manages watchers for reads and writes,
		798	supports raw and formatted I/O, I/O queued and fully transparent and
		799	non-blocking SSL/TLS.
596		800
597	=item L<AnyEvent::Socket>	801	=item L<AnyEvent::DNS>
598		802
599	Provides a means to do non-blocking connects, accepts etc.	803	Provides rich asynchronous DNS resolver capabilities.
		804
		805	=item L<AnyEvent::HTTP>
		806
		807	A simple-to-use HTTP library that is capable of making a lot of concurrent
		808	HTTP requests.
600		809
601	=item L<AnyEvent::HTTPD>	810	=item L<AnyEvent::HTTPD>
602		811
603	Provides a simple web application server framework.	812	Provides a simple web application server framework.
604		813
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>	814	=item L<AnyEvent::FastPing>
611		815
612	The fastest ping in the west.	816	The fastest ping in the west.
613		817
		818	=item L<AnyEvent::DBI>
		819
		820	Executes L<DBI> requests asynchronously in a proxy process.
		821
		822	=item L<AnyEvent::AIO>
		823
		824	Truly asynchronous I/O, should be in the toolbox of every event
		825	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		826	together.
		827
		828	=item L<AnyEvent::BDB>
		829
		830	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		831	L<BDB> and AnyEvent together.
		832
		833	=item L<AnyEvent::GPSD>
		834
		835	A non-blocking interface to gpsd, a daemon delivering GPS information.
		836
		837	=item L<AnyEvent::IGS>
		838
		839	A non-blocking interface to the Internet Go Server protocol (used by
		840	L<App::IGS>).
		841
614	=item L<Net::IRC3>	842	=item L<AnyEvent::IRC>
615		843
616	AnyEvent based IRC client module family.	844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
617		845
618	=item L<Net::XMPP2>	846	=item L<Net::XMPP2>
619		847
620	AnyEvent based XMPP (Jabber protocol) module family.	848	AnyEvent based XMPP (Jabber protocol) module family.
621		849
…		…
628		856
629	High level API for event-based execution flow control.	857	High level API for event-based execution flow control.
630		858
631	=item L<Coro>	859	=item L<Coro>
632		860
633	Has special support for AnyEvent.	861	Has special support for AnyEvent via L<Coro::AnyEvent>.
634		862
635	=item L<IO::Lambda>	863	=item L<IO::Lambda>
636		864
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638		866
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	867	=back
650		868
651	=cut	869	=cut
652		870
653	package AnyEvent;	871	package AnyEvent;
654		872
655	no warnings;	873	no warnings;
656	use strict;	874	use strict qw(vars subs);
657		875
658	use Carp;	876	use Carp;
659		877
660	our $VERSION = '3.3';	878	our $VERSION = 4.35;
661	our $MODEL;	879	our $MODEL;
662		880
663	our $AUTOLOAD;	881	our $AUTOLOAD;
664	our @ISA;	882	our @ISA;
665		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		894
668	our @REGISTRY;	895	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		896
		897	{
		898	my $idx;
		899	$PROTOCOL{$_} = ++$idx
		900	for reverse split /\s*,\s*/,
		901	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		902	}
669		903
670	my @models = (	904	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
675	[Tk:: => AnyEvent::Impl::Tk::],
676	[Wx:: => AnyEvent::Impl::POE::],
677	[Prima:: => AnyEvent::Impl::POE::],
678	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
684	);	918	);
685		919
686	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		921
		922	our @post_detect;
		923
		924	sub post_detect(&) {
		925	my ($cb) = @_;
		926
		927	if ($MODEL) {
		928	$cb->();
		929
		930	1
		931	} else {
		932	push @post_detect, $cb;
		933
		934	defined wantarray
		935	? bless \$cb, "AnyEvent::Util::PostDetect"
		936	: ()
		937	}
		938	}
		939
		940	sub AnyEvent::Util::PostDetect::DESTROY {
		941	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		942	}
687		943
688	sub detect() {	944	sub detect() {
689	unless ($MODEL) {	945	unless ($MODEL) {
690	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
691		948
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	951	if (eval "require $model") {
695	$MODEL = $model;	952	$MODEL = $model;
…		…
725	last;	982	last;
726	}	983	}
727	}	984	}
728		985
729	$MODEL	986	$MODEL
730	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
731	}	988	}
732	}	989	}
733		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
734	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		996
		997	(shift @post_detect)->() while @post_detect;
736	}	998	}
737		999
738	$MODEL	1000	$MODEL
739	}	1001	}
740		1002
…		…
748		1010
749	my $class = shift;	1011	my $class = shift;
750	$class->$func (@_);	1012	$class->$func (@_);
751	}	1013	}
752		1014
		1015	# utility function to dup a filehandle. this is used by many backends
		1016	# to support binding more than one watcher per filehandle (they usually
		1017	# allow only one watcher per fd, so we dup it to get a different one).
		1018	sub _dupfh($$$$) {
		1019	my ($poll, $fh, $r, $w) = @_;
		1020
		1021	# cygwin requires the fh mode to be matching, unix doesn't
		1022	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1023	: $poll eq "w" ? ($w, ">")
		1024	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1025
		1026	open my $fh2, "$mode&" . fileno $fh
		1027	or die "cannot dup() filehandle: $!";
		1028
		1029	# we assume CLOEXEC is already set by perl in all important cases
		1030
		1031	($fh2, $rw)
		1032	}
		1033
753	package AnyEvent::Base;	1034	package AnyEvent::Base;
754		1035
		1036	# default implementation for now and time
		1037
		1038	BEGIN {
		1039	if (eval "use Time::HiRes (); time (); 1") {
		1040	*_time = \&Time::HiRes::time;
		1041	# if (eval "use POSIX (); (POSIX::times())...
		1042	} else {
		1043	*_time = sub { time }; # epic fail
		1044	}
		1045	}
		1046
		1047	sub time { _time }
		1048	sub now { _time }
		1049
755	# default implementation for ->condvar, ->wait, ->broadcast	1050	# default implementation for ->condvar
756		1051
757	sub condvar {	1052	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	1053	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	}	1054	}
768		1055
769	# default implementation for ->signal	1056	# default implementation for ->signal
770		1057
771	our %SIG_CB;	1058	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1059
		1060	sub _signal_exec {
		1061	sysread $SIGPIPE_R, my $dummy, 4;
		1062
		1063	while (%SIG_EV) {
		1064	for (keys %SIG_EV) {
		1065	delete $SIG_EV{$_};
		1066	$_->() for values %{ $SIG_CB{$_} || {} };
		1067	}
		1068	}
		1069	}
772		1070
773	sub signal {	1071	sub signal {
774	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
775		1073
		1074	unless ($SIGPIPE_R) {
		1075	require Fcntl;
		1076
		1077	if (AnyEvent::WIN32) {
		1078	require AnyEvent::Util;
		1079
		1080	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1081	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1082	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1083	} else {
		1084	pipe $SIGPIPE_R, $SIGPIPE_W;
		1085	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1086	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1087	}
		1088
		1089	$SIGPIPE_R
		1090	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1091
		1092	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1093	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094
		1095	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1096	}
		1097
776	my $signal = uc $arg{signal}	1098	my $signal = uc $arg{signal}
777	or Carp::croak "required option 'signal' is missing";	1099	or Carp::croak "required option 'signal' is missing";
778		1100
779	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1101	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
780	$SIG{$signal} ||= sub {	1102	$SIG{$signal} ||= sub {
781	$_->() for values %{ $SIG_CB{$signal} || {} };	1103	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1104	undef $SIG_EV{$signal};
782	};	1105	};
783		1106
784	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1107	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
785	}	1108	}
786		1109
787	sub AnyEvent::Base::Signal::DESTROY {	1110	sub AnyEvent::Base::Signal::DESTROY {
788	my ($signal, $cb) = @{$_[0]};	1111	my ($signal, $cb) = @{$_[0]};
789		1112
790	delete $SIG_CB{$signal}{$cb};	1113	delete $SIG_CB{$signal}{$cb};
791		1114
792	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1115	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
793	}	1116	}
794		1117
795	# default implementation for ->child	1118	# default implementation for ->child
796		1119
797	our %PID_CB;	1120	our %PID_CB;
…		…
824	or Carp::croak "required option 'pid' is missing";	1147	or Carp::croak "required option 'pid' is missing";
825		1148
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1149	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1150
828	unless ($WNOHANG) {	1151	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1152	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
830	}	1153	}
831		1154
832	unless ($CHLD_W) {	1155	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1156	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# child could be a zombie already, so make at least one round	1157	# child could be a zombie already, so make at least one round
…		…
844	delete $PID_CB{$pid}{$cb};	1167	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1168	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1169
847	undef $CHLD_W unless keys %PID_CB;	1170	undef $CHLD_W unless keys %PID_CB;
848	}	1171	}
		1172
		1173	package AnyEvent::CondVar;
		1174
		1175	our @ISA = AnyEvent::CondVar::Base::;
		1176
		1177	package AnyEvent::CondVar::Base;
		1178
		1179	use overload
		1180	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1181	fallback => 1;
		1182
		1183	sub _send {
		1184	# nop
		1185	}
		1186
		1187	sub send {
		1188	my $cv = shift;
		1189	$cv->{_ae_sent} = [@_];
		1190	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1191	$cv->_send;
		1192	}
		1193
		1194	sub croak {
		1195	$_[0]{_ae_croak} = $_[1];
		1196	$_[0]->send;
		1197	}
		1198
		1199	sub ready {
		1200	$_[0]{_ae_sent}
		1201	}
		1202
		1203	sub _wait {
		1204	AnyEvent->one_event while !$_[0]{_ae_sent};
		1205	}
		1206
		1207	sub recv {
		1208	$_[0]->_wait;
		1209
		1210	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1211	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1212	}
		1213
		1214	sub cb {
		1215	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1216	$_[0]{_ae_cb}
		1217	}
		1218
		1219	sub begin {
		1220	++$_[0]{_ae_counter};
		1221	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1222	}
		1223
		1224	sub end {
		1225	return if --$_[0]{_ae_counter};
		1226	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1227	}
		1228
		1229	# undocumented/compatibility with pre-3.4
		1230	*broadcast = \&send;
		1231	*wait = \&_wait;
		1232
		1233	=head1 ERROR AND EXCEPTION HANDLING
		1234
		1235	In general, AnyEvent does not do any error handling - it relies on the
		1236	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1237	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1238	checking of all AnyEvent methods, however, which is highly useful during
		1239	development.
		1240
		1241	As for exception handling (i.e. runtime errors and exceptions thrown while
		1242	executing a callback), this is not only highly event-loop specific, but
		1243	also not in any way wrapped by this module, as this is the job of the main
		1244	program.
		1245
		1246	The pure perl event loop simply re-throws the exception (usually
		1247	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1248	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1249	so on.
		1250
		1251	=head1 ENVIRONMENT VARIABLES
		1252
		1253	The following environment variables are used by this module or its
		1254	submodules:
		1255
		1256	=over 4
		1257
		1258	=item C<PERL_ANYEVENT_VERBOSE>
		1259
		1260	By default, AnyEvent will be completely silent except in fatal
		1261	conditions. You can set this environment variable to make AnyEvent more
		1262	talkative.
		1263
		1264	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1265	conditions, such as not being able to load the event model specified by
		1266	C<PERL_ANYEVENT_MODEL>.
		1267
		1268	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1269	model it chooses.
		1270
		1271	=item C<PERL_ANYEVENT_STRICT>
		1272
		1273	AnyEvent does not do much argument checking by default, as thorough
		1274	argument checking is very costly. Setting this variable to a true value
		1275	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1276	check the arguments passed to most method calls. If it finds any problems
		1277	it will croak.
		1278
		1279	In other words, enables "strict" mode.
		1280
		1281	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1282	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1283	developing programs can be very useful, however.
		1284
		1285	=item C<PERL_ANYEVENT_MODEL>
		1286
		1287	This can be used to specify the event model to be used by AnyEvent, before
		1288	auto detection and -probing kicks in. It must be a string consisting
		1289	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1290	and the resulting module name is loaded and if the load was successful,
		1291	used as event model. If it fails to load AnyEvent will proceed with
		1292	auto detection and -probing.
		1293
		1294	This functionality might change in future versions.
		1295
		1296	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1297	could start your program like this:
		1298
		1299	PERL_ANYEVENT_MODEL=Perl perl ...
		1300
		1301	=item C<PERL_ANYEVENT_PROTOCOLS>
		1302
		1303	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1304	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1305	of auto probing).
		1306
		1307	Must be set to a comma-separated list of protocols or address families,
		1308	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1309	used, and preference will be given to protocols mentioned earlier in the
		1310	list.
		1311
		1312	This variable can effectively be used for denial-of-service attacks
		1313	against local programs (e.g. when setuid), although the impact is likely
		1314	small, as the program has to handle conenction and other failures anyways.
		1315
		1316	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1317	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1318	- only support IPv4, never try to resolve or contact IPv6
		1319	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1320	IPv6, but prefer IPv6 over IPv4.
		1321
		1322	=item C<PERL_ANYEVENT_EDNS0>
		1323
		1324	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1325	for DNS. This extension is generally useful to reduce DNS traffic, but
		1326	some (broken) firewalls drop such DNS packets, which is why it is off by
		1327	default.
		1328
		1329	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1330	EDNS0 in its DNS requests.
		1331
		1332	=item C<PERL_ANYEVENT_MAX_FORKS>
		1333
		1334	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1335	will create in parallel.
		1336
		1337	=back
849		1338
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1339	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1340
852	This is an advanced topic that you do not normally need to use AnyEvent in	1341	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	1342	a module. This section is only of use to event loop authors who want to
…		…
887		1376
888	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1377	I<rxvt-unicode> also cheats a bit by not providing blocking access to
889	condition variables: code blocking while waiting for a condition will	1378	condition variables: code blocking while waiting for a condition will
890	C<die>. This still works with most modules/usages, and blocking calls must	1379	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.	1380	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		1381
930	=head1 EXAMPLE PROGRAM	1382	=head1 EXAMPLE PROGRAM
931		1383
932	The following program uses an I/O watcher to read data from STDIN, a timer	1384	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	1385	to display a message once per second, and a condition variable to quit the
…		…
942	poll => 'r',	1394	poll => 'r',
943	cb => sub {	1395	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1396	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1397	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1398	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1399	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1400	},
949	);	1401	);
950		1402
951	my $time_watcher; # can only be used once	1403	my $time_watcher; # can only be used once
952		1404
…		…
957	});	1409	});
958	}	1410	}
959		1411
960	new_timer; # create first timer	1412	new_timer; # create first timer
961		1413
962	$cv->wait; # wait until user enters /^q/i	1414	$cv->recv; # wait until user enters /^q/i
963		1415
964	=head1 REAL-WORLD EXAMPLE	1416	=head1 REAL-WORLD EXAMPLE
965		1417
966	Consider the L<Net::FCP> module. It features (among others) the following	1418	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:	1419	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1469	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1470	or die "connection or write error";
1019	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1471	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020		1472
1021	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1473	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:	1474	result and signals any possible waiters that the request has finished:
1023		1475
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1476	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1477
1026	if (end-of-file or data complete) {	1478	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1479	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1480	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1481	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1482	}
1031		1483
1032	The C<result> method, finally, just waits for the finished signal (if the	1484	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	1485	request was already finished, it doesn't wait, of course, and returns the
1034	data:	1486	data:
1035		1487
1036	$txn->{finished}->wait;	1488	$txn->{finished}->recv;
1037	return $txn->{result};	1489	return $txn->{result};
1038		1490
1039	The actual code goes further and collects all errors (C<die>s, exceptions)	1491	The actual code goes further and collects all errors (C<die>s, exceptions)
1040	that occured during request processing. The C<result> method detects	1492	that occurred during request processing. The C<result> method detects
1041	whether an exception as thrown (it is stored inside the $txn object)	1493	whether an exception as thrown (it is stored inside the $txn object)
1042	and just throws the exception, which means connection errors and other	1494	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	1495	problems get reported tot he code that tries to use the result, not in a
1044	random callback.	1496	random callback.
1045		1497
…		…
1076		1528
1077	my $quit = AnyEvent->condvar;	1529	my $quit = AnyEvent->condvar;
1078		1530
1079	$fcp->txn_client_get ($url)->cb (sub {	1531	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1532	...
1081	$quit->broadcast;	1533	$quit->send;
1082	});	1534	});
1083		1535
1084	$quit->wait;	1536	$quit->recv;
1085		1537
1086		1538
1087	=head1 BENCHMARKS	1539	=head1 BENCHMARKS
1088		1540
1089	To give you an idea of the performance and overheads that AnyEvent adds	1541	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1091	of various event loops I prepared some benchmarks.	1543	of various event loops I prepared some benchmarks.
1092		1544
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1545	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1546
1095	Here is a benchmark of various supported event models used natively and	1547	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	1548	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,	1549	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.	1550	which it is), lets them fire exactly once and destroys them again.
1099		1551
1100	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1552	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101	distribution.	1553	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1570	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1571	and memory usage is not included in the figures.
1120		1572
1121	I<invoke> is the time, in microseconds, used to invoke a simple	1573	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	1574	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	1575	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1576	signal the end of this phase.
1125		1577
1126	I<destroy> is the time, in microseconds, that it takes to destroy a single	1578	I<destroy> is the time, in microseconds, that it takes to destroy a single
1127	watcher.	1579	watcher.
1128		1580
1129	=head3 Results	1581	=head3 Results
1130		1582
1131	name watchers bytes create invoke destroy comment	1583	name watchers bytes create invoke destroy comment
1132	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1584	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	1585	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	1586	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	1587	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	1588	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	1589	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	1590	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	1591	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	1592	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	1593	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1142		1594
1143	=head3 Discussion	1595	=head3 Discussion
1144		1596
1145	The benchmark does I<not> measure scalability of the event loop very	1597	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)	1598	well. For example, a select-based event loop (such as the pure perl one)
…		…
1224		1676
1225	=back	1677	=back
1226		1678
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1679	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1680
1229	This benchmark atcually benchmarks the event loop itself. It works by	1681	This benchmark actually benchmarks the event loop itself. It works by
1230	creating a number of "servers": each server consists of a socketpair, a	1682	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	1683	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	1684	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".	1685	watcher reads a byte it will write that byte to a random other "server".
1234		1686
1235	The effect is that there will be a lot of I/O watchers, only part of which	1687	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	1688	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	1689	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	1690	timeout is reset each time something is read because that reflects how
1239	most timeouts work (and puts extra pressure on the event loops).	1691	most timeouts work (and puts extra pressure on the event loops).
1240		1692
1241	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1693	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	1694	(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.	1695	connections, most of which are idle at any one point in time.
1244		1696
1245	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1697	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246	distribution.	1698	distribution.
…		…
1248	=head3 Explanation of the columns	1700	=head3 Explanation of the columns
1249		1701
1250	I<sockets> is the number of sockets, and twice the number of "servers" (as	1702	I<sockets> is the number of sockets, and twice the number of "servers" (as
1251	each server has a read and write socket end).	1703	each server has a read and write socket end).
1252		1704
1253	I<create> is the time it takes to create a socketpair (which is	1705	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.	1706	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255		1707
1256	I<request>, the most important value, is the time it takes to handle a	1708	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	1709	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	1710	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	1783	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1784	them).
1333		1785
1334	EV is again fastest.	1786	EV is again fastest.
1335		1787
1336	Perl again comes second. It is noticably faster than the C-based event	1788	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	1789	loops Event and Glib, although the difference is too small to really
1338	matter.	1790	matter.
1339		1791
1340	POE also performs much better in this case, but is is still far behind the	1792	POE also performs much better in this case, but is is still far behind the
1341	others.	1793	others.
…		…
1346		1798
1347	=item * C-based event loops perform very well with small number of	1799	=item * C-based event loops perform very well with small number of
1348	watchers, as the management overhead dominates.	1800	watchers, as the management overhead dominates.
1349		1801
1350	=back	1802	=back
		1803
		1804
		1805	=head1 SIGNALS
		1806
		1807	AnyEvent currently installs handlers for these signals:
		1808
		1809	=over 4
		1810
		1811	=item SIGCHLD
		1812
		1813	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1814	emulation for event loops that do not support them natively. Also, some
		1815	event loops install a similar handler.
		1816
		1817	=item SIGPIPE
		1818
		1819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1820	when AnyEvent gets loaded.
		1821
		1822	The rationale for this is that AnyEvent users usually do not really depend
		1823	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1824	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1825	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1826	some random socket.
		1827
		1828	The rationale for installing a no-op handler as opposed to ignoring it is
		1829	that this way, the handler will be restored to defaults on exec.
		1830
		1831	Feel free to install your own handler, or reset it to defaults.
		1832
		1833	=back
		1834
		1835	=cut
		1836
		1837	$SIG{PIPE} = sub { }
		1838	unless defined $SIG{PIPE};
1351		1839
1352		1840
1353	=head1 FORK	1841	=head1 FORK
1354		1842
1355	Most event libraries are not fork-safe. The ones who are usually are	1843	Most event libraries are not fork-safe. The ones who are usually are
…		…
1370	specified in the variable.	1858	specified in the variable.
1371		1859
1372	You can make AnyEvent completely ignore this variable by deleting it	1860	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:	1861	before the first watcher gets created, e.g. with a C<BEGIN> block:
1374		1862
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1863	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		1864
1377	use AnyEvent;	1865	use AnyEvent;
		1866
		1867	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1868	be used to probe what backend is used and gain other information (which is
		1869	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1870	$ENV{PERL_ANYEGENT_STRICT}.
		1871
		1872
		1873	=head1 BUGS
		1874
		1875	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1876	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1877	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1878	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1879	pronounced).
1378		1880
1379		1881
1380	=head1 SEE ALSO	1882	=head1 SEE ALSO
1381		1883
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1884	Utility functions: L<AnyEvent::Util>.
1383	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1885
		1886	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	1887	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		1888
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1889	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1890	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>,	1891	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1892	L<AnyEvent::Impl::POE>.
1390		1893
		1894	Non-blocking file handles, sockets, TCP clients and
		1895	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1896
		1897	Asynchronous DNS: L<AnyEvent::DNS>.
		1898
		1899	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1900
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1901	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		1902
1393		1903
1394	=head1 AUTHOR	1904	=head1 AUTHOR
1395		1905
1396	Marc Lehmann <schmorp@schmorp.de>	1906	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	1907	http://home.schmorp.de/
1398		1908
1399	=cut	1909	=cut
1400		1910
1401	1	1911	1
1402		1912

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