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Revision 1.205 by root, Sun Apr 19 12:09:46 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	=item AnyEvent->now_update
		326
		327	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		328	the current time for each loop iteration (see the discussion of L<<
		329	AnyEvent->now >>, above).
		330
		331	When a callback runs for a long time (or when the process sleeps), then
		332	this "current" time will differ substantially from the real time, which
		333	might affect timers and time-outs.
		334
		335	When this is the case, you can call this method, which will update the
		336	event loop's idea of "current time".
		337
		338	Note that updating the time I<might> cause some events to be handled.
		339
		340	=back
		341
232	=head2 SIGNAL WATCHERS	342	=head2 SIGNAL WATCHERS
233		343
234	You can watch for signals using a signal watcher, C<signal> is the signal	344	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	345	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	346	callback to be invoked whenever a signal occurs.
237		347
238	Although the callback might get passed parameters, their value and	348	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	349	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	350	callbacks cannot use arguments passed to signal watcher callbacks.
241		351
242	Multiple signal occurances can be clumped together into one callback	352	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	353	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	354	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.	355	but it is guaranteed not to interrupt any other callbacks.
246		356
247	The main advantage of using these watchers is that you can share a signal	357	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	358	between multiple watchers.
249		359
250	This watcher might use C<%SIG>, so programs overwriting those signals	360	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	367	=head2 CHILD PROCESS WATCHERS
258		368
259	You can also watch on a child process exit and catch its exit status.	369	You can also watch on a child process exit and catch its exit status.
260		370
261	The child process is specified by the C<pid> argument (if set to C<0>, it	371	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	372	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	373	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	374	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	375
266	you I<can> rely on child watcher callback arguments.	376	The callback will be called with the pid and exit status (as returned by
		377	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		378	callback arguments.
		379
		380	This watcher type works by installing a signal handler for C<SIGCHLD>,
		381	and since it cannot be shared, nothing else should use SIGCHLD or reap
		382	random child processes (waiting for specific child processes, e.g. inside
		383	C<system>, is just fine).
267		384
268	There is a slight catch to child watchers, however: you usually start them	385	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	386	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	387	have exited already (and no SIGCHLD will be sent anymore).
271		388
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	394	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>).	395	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		396
280	Example: fork a process and wait for it	397	Example: fork a process and wait for it
281		398
282	my $done = AnyEvent->condvar;	399	my $done = AnyEvent->condvar;
283		400
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	401	my $pid = fork or exit 5;
287		402
288	my $w = AnyEvent->child (	403	my $w = AnyEvent->child (
289	pid => $pid,	404	pid => $pid,
290	cb => sub {	405	cb => sub {
291	my ($pid, $status) = @_;	406	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	407	warn "pid $pid exited with status $status";
293	$done->broadcast;	408	$done->send;
294	},	409	},
295	);	410	);
296		411
297	# do something else, then wait for process exit	412	# do something else, then wait for process exit
298	$done->wait;	413	$done->recv;
299		414
300	=head2 CONDITION VARIABLES	415	=head2 CONDITION VARIABLES
301		416
302	If you are familiar with some event loops you will know that all of them	417	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	418	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	424	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	425	because they represent a condition that must become true.
311		426
312	Condition variables can be created by calling the C<< AnyEvent->condvar	427	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	428	>> method, usually without arguments. The only argument pair allowed is
		429
314	C<cb>, which specifies a callback to be called when the condition variable	430	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	431	becomes true, with the condition variable as the first argument (but not
		432	the results).
316		433
317	After creation, the conditon variable is "false" until it becomes "true"	434	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	435	by calling the C<send> method (or calling the condition variable as if it
		436	were a callback, read about the caveats in the description for the C<<
		437	->send >> method).
319		438
320	Condition variables are similar to callbacks, except that you can	439	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	440	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	441	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	442	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	443	used to represent a transaction, which finishes at some point and delivers
325	a result.	444	a result.
326		445
327	Condition variables are very useful to signal that something has finished,	446	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	447	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	448	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	449	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	450	called or can synchronously C<< ->recv >> for the results.
332		451
333	You can also use them to simulate traditional event loops - for example,	452	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	453	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	454	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.	455	button of your app, which would C<< ->send >> the "quit" event.
337		456
338	Note that condition variables recurse into the event loop - if you have	457	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	458	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	459	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,	460	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	461	as this asks for trouble.
343		462
344	Condition variables are represented by hash refs in perl, and the keys	463	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	465	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	466	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	467	it's C<new> method in your own C<new> method.
349		468
350	There are two "sides" to a condition variable - the "producer side" which	469	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	470	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	471	for the send to occur.
353		472
354	Example:	473	Example: wait for a timer.
355		474
356	# wait till the result is ready	475	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	476	my $result_ready = AnyEvent->condvar;
358		477
359	# do something such as adding a timer	478	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	479	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	480	# when the "result" is ready.
362	# in this case, we simply use a timer:	481	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	482	my $w = AnyEvent->timer (
364	after => 1,	483	after => 1,
365	cb => sub { $result_ready->broadcast },	484	cb => sub { $result_ready->send },
366	);	485	);
367		486
368	# this "blocks" (while handling events) till the callback	487	# this "blocks" (while handling events) till the callback
369	# calls broadcast	488	# calls send
370	$result_ready->wait;	489	$result_ready->recv;
		490
		491	Example: wait for a timer, but take advantage of the fact that
		492	condition variables are also code references.
		493
		494	my $done = AnyEvent->condvar;
		495	my $delay = AnyEvent->timer (after => 5, cb => $done);
		496	$done->recv;
		497
		498	Example: Imagine an API that returns a condvar and doesn't support
		499	callbacks. This is how you make a synchronous call, for example from
		500	the main program:
		501
		502	use AnyEvent::CouchDB;
		503
		504	...
		505
		506	my @info = $couchdb->info->recv;
		507
		508	And this is how you would just ste a callback to be called whenever the
		509	results are available:
		510
		511	$couchdb->info->cb (sub {
		512	my @info = $_[0]->recv;
		513	});
371		514
372	=head3 METHODS FOR PRODUCERS	515	=head3 METHODS FOR PRODUCERS
373		516
374	These methods should only be used by the producing side, i.e. the	517	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	518	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	519	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	520	uncommon for the consumer to create it as well.
378		521
379	=over 4	522	=over 4
380		523
381	=item $cv->broadcast (...)	524	=item $cv->send (...)
382		525
383	Flag the condition as ready - a running C<< ->wait >> and all further	526	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	527	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	528	called. If nobody is waiting the send will be remembered.
386		529
387	If a callback has been set on the condition variable, it is called	530	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	531	immediately from within send.
389		532
390	Any arguments passed to the C<broadcast> call will be returned by all	533	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	534	future C<< ->recv >> calls.
		535
		536	Condition variables are overloaded so one can call them directly
		537	(as a code reference). Calling them directly is the same as calling
		538	C<send>. Note, however, that many C-based event loops do not handle
		539	overloading, so as tempting as it may be, passing a condition variable
		540	instead of a callback does not work. Both the pure perl and EV loops
		541	support overloading, however, as well as all functions that use perl to
		542	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		543	example).
392		544
393	=item $cv->croak ($error)	545	=item $cv->croak ($error)
394		546
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	547	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	548	C<Carp::croak> with the given error message/object/scalar.
397		549
398	This can be used to signal any errors to the condition variable	550	This can be used to signal any errors to the condition variable
399	user/consumer.	551	user/consumer.
400		552
401	=item $cv->begin ([group callback])	553	=item $cv->begin ([group callback])
402		554
403	=item $cv->end	555	=item $cv->end
		556
		557	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		558
405	These two methods can be used to combine many transactions/events into	559	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	560	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	561	to use a condition variable for the whole process.
408		562
409	Every call to C<< ->begin >> will increment a counter, and every call to	563	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	564	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	565	>>, 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	566	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.	567	callback was set, C<send> will be called without any arguments.
414		568
415	Let's clarify this with the ping example:	569	Let's clarify this with the ping example:
416		570
417	my $cv = AnyEvent->condvar;	571	my $cv = AnyEvent->condvar;
418		572
419	my %result;	573	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	574	$cv->begin (sub { $cv->send (\%result) });
421		575
422	for my $host (@list_of_hosts) {	576	for my $host (@list_of_hosts) {
423	$cv->begin;	577	$cv->begin;
424	ping_host_then_call_callback $host, sub {	578	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	579	$result{$host} = ...;
…		…
428	}	582	}
429		583
430	$cv->end;	584	$cv->end;
431		585
432	This code fragment supposedly pings a number of hosts and calls	586	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	587	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	588	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	589	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	590	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	591	results arrive is not relevant.
438		592
439	There is an additional bracketing call to C<begin> and C<end> outside the	593	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	594	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	595	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	596	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	597	doesn't execute once).
444		598
445	This is the general pattern when you "fan out" into multiple subrequests:	599	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>	600	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	601	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>.	602	C<begin> and for each subrequest you finish, call C<end>.
449		603
450	=back	604	=back
451		605
452	=head3 METHODS FOR CONSUMERS	606	=head3 METHODS FOR CONSUMERS
453		607
454	These methods should only be used by the consuming side, i.e. the	608	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	609	code awaits the condition.
456		610
457	=item $cv->wait	611	=over 4
458		612
		613	=item $cv->recv
		614
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	615	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	616	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	617	normally.
462		618
463	You can only wait once on a condition - additional calls are valid but	619	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	620	will return immediately.
465		621
466	If an error condition has been set by calling C<< ->croak >>, then this	622	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	623	function will call C<croak>.
468		624
469	In list context, all parameters passed to C<broadcast> will be returned,	625	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	626	in scalar context only the first one will be returned.
471		627
472	Not all event models support a blocking wait - some die in that case	628	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	629	(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	630	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	631	caller decide whether the call will block or not (for example, by coupling
476	condition variables with some kind of request results and supporting	632	condition variables with some kind of request results and supporting
477	callbacks so the caller knows that getting the result will not block,	633	callbacks so the caller knows that getting the result will not block,
478	while still suppporting blocking waits if the caller so desires).	634	while still supporting blocking waits if the caller so desires).
479		635
480	Another reason I<never> to C<< ->wait >> in a module is that you cannot	636	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	637	sensibly have two C<< ->recv >>'s in parallel, as that would require
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	638	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	639	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		640
		641	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		642	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		643	versions and also integrates coroutines into AnyEvent, making blocking
		644	C<< ->recv >> calls perfectly safe as long as they are done from another
		645	coroutine (one that doesn't run the event loop).
		646
487	You can ensure that C<< -wait >> never blocks by setting a callback and	647	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	648	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	649	time). This will work even when the event loop does not support blocking
490	waits otherwise.	650	waits otherwise.
		651
		652	=item $bool = $cv->ready
		653
		654	Returns true when the condition is "true", i.e. whether C<send> or
		655	C<croak> have been called.
		656
		657	=item $cb = $cv->cb ($cb->($cv))
		658
		659	This is a mutator function that returns the callback set and optionally
		660	replaces it before doing so.
		661
		662	The callback will be called when the condition becomes "true", i.e. when
		663	C<send> or C<croak> are called, with the only argument being the condition
		664	variable itself. Calling C<recv> inside the callback or at any later time
		665	is guaranteed not to block.
491		666
492	=back	667	=back
493		668
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	669	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		670
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	678	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	679	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		680
506	The known classes so far are:	681	The known classes so far are:
507		682
508	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	683	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	684	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	685	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	686	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	687	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	704	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	if necessary. You should only call this function right before you would	705	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	706	have created an AnyEvent watcher anyway, that is, as late as possible at
534	runtime.	707	runtime.
535		708
		709	=item $guard = AnyEvent::post_detect { BLOCK }
		710
		711	Arranges for the code block to be executed as soon as the event model is
		712	autodetected (or immediately if this has already happened).
		713
		714	If called in scalar or list context, then it creates and returns an object
		715	that automatically removes the callback again when it is destroyed. See
		716	L<Coro::BDB> for a case where this is useful.
		717
		718	=item @AnyEvent::post_detect
		719
		720	If there are any code references in this array (you can C<push> to it
		721	before or after loading AnyEvent), then they will called directly after
		722	the event loop has been chosen.
		723
		724	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		725	if it contains a true value then the event loop has already been detected,
		726	and the array will be ignored.
		727
		728	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		729
536	=back	730	=back
537		731
538	=head1 WHAT TO DO IN A MODULE	732	=head1 WHAT TO DO IN A MODULE
539		733
540	As a module author, you should C<use AnyEvent> and call AnyEvent methods	734	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	737	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	738	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	739	by calling AnyEvent in your module body you force the user of your module
546	to load the event module first.	740	to load the event module first.
547		741
548	Never call C<< ->wait >> on a condition variable unless you I<know> that	742	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	743	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	744	because it will stall the whole program, and the whole point of using
551	events is to stay interactive.	745	events is to stay interactive.
552		746
553	It is fine, however, to call C<< ->wait >> when the user of your module	747	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	748	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 >>	749	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).	750	freely, as the user of your module knows what she is doing. always).
557		751
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	752	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		753
560	There will always be a single main program - the only place that should	754	There will always be a single main program - the only place that should
…		…
562		756
563	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	757	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	758	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.	759	decide which implementation to chose if some module relies on it.
566		760
567	If the main program relies on a specific event model. For example, in	761	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	762	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	763	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	764	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	765	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	766	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.	767	might chose the wrong one unless you load the correct one yourself.
574		768
575	You can chose to use a rather inefficient pure-perl implementation by	769	You can chose to use a pure-perl implementation by loading the
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	770	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	behaviour everywhere, but letting AnyEvent chose is generally better.	771	everywhere, but letting AnyEvent chose the model is generally better.
		772
		773	=head2 MAINLOOP EMULATION
		774
		775	Sometimes (often for short test scripts, or even standalone programs who
		776	only want to use AnyEvent), you do not want to run a specific event loop.
		777
		778	In that case, you can use a condition variable like this:
		779
		780	AnyEvent->condvar->recv;
		781
		782	This has the effect of entering the event loop and looping forever.
		783
		784	Note that usually your program has some exit condition, in which case
		785	it is better to use the "traditional" approach of storing a condition
		786	variable somewhere, waiting for it, and sending it when the program should
		787	exit cleanly.
		788
578		789
579	=head1 OTHER MODULES	790	=head1 OTHER MODULES
580		791
581	The following is a non-exhaustive list of additional modules that use	792	The following is a non-exhaustive list of additional modules that use
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	793	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
588	=item L<AnyEvent::Util>	799	=item L<AnyEvent::Util>
589		800
590	Contains various utility functions that replace often-used but blocking	801	Contains various utility functions that replace often-used but blocking
591	functions such as C<inet_aton> by event-/callback-based versions.	802	functions such as C<inet_aton> by event-/callback-based versions.
592		803
		804	=item L<AnyEvent::Socket>
		805
		806	Provides various utility functions for (internet protocol) sockets,
		807	addresses and name resolution. Also functions to create non-blocking tcp
		808	connections or tcp servers, with IPv6 and SRV record support and more.
		809
593	=item L<AnyEvent::Handle>	810	=item L<AnyEvent::Handle>
594		811
595	Provide read and write buffers and manages watchers for reads and writes.	812	Provide read and write buffers, manages watchers for reads and writes,
		813	supports raw and formatted I/O, I/O queued and fully transparent and
		814	non-blocking SSL/TLS.
596		815
597	=item L<AnyEvent::Socket>	816	=item L<AnyEvent::DNS>
598		817
599	Provides a means to do non-blocking connects, accepts etc.	818	Provides rich asynchronous DNS resolver capabilities.
		819
		820	=item L<AnyEvent::HTTP>
		821
		822	A simple-to-use HTTP library that is capable of making a lot of concurrent
		823	HTTP requests.
600		824
601	=item L<AnyEvent::HTTPD>	825	=item L<AnyEvent::HTTPD>
602		826
603	Provides a simple web application server framework.	827	Provides a simple web application server framework.
604		828
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>	829	=item L<AnyEvent::FastPing>
611		830
612	The fastest ping in the west.	831	The fastest ping in the west.
613		832
		833	=item L<AnyEvent::DBI>
		834
		835	Executes L<DBI> requests asynchronously in a proxy process.
		836
		837	=item L<AnyEvent::AIO>
		838
		839	Truly asynchronous I/O, should be in the toolbox of every event
		840	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		841	together.
		842
		843	=item L<AnyEvent::BDB>
		844
		845	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		846	L<BDB> and AnyEvent together.
		847
		848	=item L<AnyEvent::GPSD>
		849
		850	A non-blocking interface to gpsd, a daemon delivering GPS information.
		851
		852	=item L<AnyEvent::IGS>
		853
		854	A non-blocking interface to the Internet Go Server protocol (used by
		855	L<App::IGS>).
		856
614	=item L<Net::IRC3>	857	=item L<AnyEvent::IRC>
615		858
616	AnyEvent based IRC client module family.	859	AnyEvent based IRC client module family (replacing the older Net::IRC3).
617		860
618	=item L<Net::XMPP2>	861	=item L<Net::XMPP2>
619		862
620	AnyEvent based XMPP (Jabber protocol) module family.	863	AnyEvent based XMPP (Jabber protocol) module family.
621		864
…		…
628		871
629	High level API for event-based execution flow control.	872	High level API for event-based execution flow control.
630		873
631	=item L<Coro>	874	=item L<Coro>
632		875
633	Has special support for AnyEvent.	876	Has special support for AnyEvent via L<Coro::AnyEvent>.
634		877
635	=item L<IO::Lambda>	878	=item L<IO::Lambda>
636		879
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	880	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638		881
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	882	=back
650		883
651	=cut	884	=cut
652		885
653	package AnyEvent;	886	package AnyEvent;
654		887
655	no warnings;	888	no warnings;
656	use strict;	889	use strict qw(vars subs);
657		890
658	use Carp;	891	use Carp;
659		892
660	our $VERSION = '3.3';	893	our $VERSION = 4.351;
661	our $MODEL;	894	our $MODEL;
662		895
663	our $AUTOLOAD;	896	our $AUTOLOAD;
664	our @ISA;	897	our @ISA;
665		898
		899	our @REGISTRY;
		900
		901	our $WIN32;
		902
		903	BEGIN {
		904	my $win32 = ! ! ($^O =~ /mswin32/i);
		905	eval "sub WIN32(){ $win32 }";
		906	}
		907
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	908	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		909
668	our @REGISTRY;	910	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		911
		912	{
		913	my $idx;
		914	$PROTOCOL{$_} = ++$idx
		915	for reverse split /\s*,\s*/,
		916	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		917	}
669		918
670	my @models = (	919	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	920	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	921	[Event:: => AnyEvent::Impl::Event::],
675	[Tk:: => AnyEvent::Impl::Tk::],
676	[Wx:: => AnyEvent::Impl::POE::],
677	[Prima:: => AnyEvent::Impl::POE::],
678	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	922	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	923	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	924	# as the pureperl backend should work everywhere
		925	# and is usually faster
		926	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		927	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	928	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	929	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	930	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		931	[Wx:: => AnyEvent::Impl::POE::],
		932	[Prima:: => AnyEvent::Impl::POE::],
684	);	933	);
685		934
686	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	935	our %method = map +($_ => 1),
		936	qw(io timer time now now_update signal child condvar one_event DESTROY);
		937
		938	our @post_detect;
		939
		940	sub post_detect(&) {
		941	my ($cb) = @_;
		942
		943	if ($MODEL) {
		944	$cb->();
		945
		946	1
		947	} else {
		948	push @post_detect, $cb;
		949
		950	defined wantarray
		951	? bless \$cb, "AnyEvent::Util::PostDetect"
		952	: ()
		953	}
		954	}
		955
		956	sub AnyEvent::Util::PostDetect::DESTROY {
		957	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		958	}
687		959
688	sub detect() {	960	sub detect() {
689	unless ($MODEL) {	961	unless ($MODEL) {
690	no strict 'refs';	962	no strict 'refs';
		963	local $SIG{__DIE__};
691		964
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	965	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	966	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	967	if (eval "require $model") {
695	$MODEL = $model;	968	$MODEL = $model;
…		…
725	last;	998	last;
726	}	999	}
727	}	1000	}
728		1001
729	$MODEL	1002	$MODEL
730	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1003	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
731	}	1004	}
732	}	1005	}
733		1006
		1007	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1008
734	unshift @ISA, $MODEL;	1009	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1010
		1011	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1012
		1013	(shift @post_detect)->() while @post_detect;
736	}	1014	}
737		1015
738	$MODEL	1016	$MODEL
739	}	1017	}
740		1018
…		…
748		1026
749	my $class = shift;	1027	my $class = shift;
750	$class->$func (@_);	1028	$class->$func (@_);
751	}	1029	}
752		1030
		1031	# utility function to dup a filehandle. this is used by many backends
		1032	# to support binding more than one watcher per filehandle (they usually
		1033	# allow only one watcher per fd, so we dup it to get a different one).
		1034	sub _dupfh($$$$) {
		1035	my ($poll, $fh, $r, $w) = @_;
		1036
		1037	# cygwin requires the fh mode to be matching, unix doesn't
		1038	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1039	: $poll eq "w" ? ($w, ">")
		1040	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1041
		1042	open my $fh2, "$mode&" . fileno $fh
		1043	or die "cannot dup() filehandle: $!,";
		1044
		1045	# we assume CLOEXEC is already set by perl in all important cases
		1046
		1047	($fh2, $rw)
		1048	}
		1049
753	package AnyEvent::Base;	1050	package AnyEvent::Base;
754		1051
		1052	# default implementations for many methods
		1053
		1054	BEGIN {
		1055	if (eval "use Time::HiRes (); time (); 1") {
		1056	*_time = \&Time::HiRes::time;
		1057	# if (eval "use POSIX (); (POSIX::times())...
		1058	} else {
		1059	*_time = sub { time }; # epic fail
		1060	}
		1061	}
		1062
		1063	sub time { _time }
		1064	sub now { _time }
		1065	sub now_update { }
		1066
755	# default implementation for ->condvar, ->wait, ->broadcast	1067	# default implementation for ->condvar
756		1068
757	sub condvar {	1069	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	1070	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	}	1071	}
768		1072
769	# default implementation for ->signal	1073	# default implementation for ->signal
770		1074
771	our %SIG_CB;	1075	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1076
		1077	sub _signal_exec {
		1078	sysread $SIGPIPE_R, my $dummy, 4;
		1079
		1080	while (%SIG_EV) {
		1081	for (keys %SIG_EV) {
		1082	delete $SIG_EV{$_};
		1083	$_->() for values %{ $SIG_CB{$_} || {} };
		1084	}
		1085	}
		1086	}
772		1087
773	sub signal {	1088	sub signal {
774	my (undef, %arg) = @_;	1089	my (undef, %arg) = @_;
775		1090
		1091	unless ($SIGPIPE_R) {
		1092	require Fcntl;
		1093
		1094	if (AnyEvent::WIN32) {
		1095	require AnyEvent::Util;
		1096
		1097	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1098	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1099	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1100	} else {
		1101	pipe $SIGPIPE_R, $SIGPIPE_W;
		1102	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1103	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1104	}
		1105
		1106	$SIGPIPE_R
		1107	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1108
		1109	# not strictly required, as $^F is normally 2, but let's make sure...
		1110	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1111	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1112
		1113	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1114	}
		1115
776	my $signal = uc $arg{signal}	1116	my $signal = uc $arg{signal}
777	or Carp::croak "required option 'signal' is missing";	1117	or Carp::croak "required option 'signal' is missing";
778		1118
779	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1119	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
780	$SIG{$signal} ||= sub {	1120	$SIG{$signal} ||= sub {
781	$_->() for values %{ $SIG_CB{$signal} || {} };	1121	local $!;
		1122	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1123	undef $SIG_EV{$signal};
782	};	1124	};
783		1125
784	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1126	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
785	}	1127	}
786		1128
787	sub AnyEvent::Base::Signal::DESTROY {	1129	sub AnyEvent::Base::Signal::DESTROY {
788	my ($signal, $cb) = @{$_[0]};	1130	my ($signal, $cb) = @{$_[0]};
789		1131
790	delete $SIG_CB{$signal}{$cb};	1132	delete $SIG_CB{$signal}{$cb};
791		1133
792	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1134	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
793	}	1135	}
794		1136
795	# default implementation for ->child	1137	# default implementation for ->child
796		1138
797	our %PID_CB;	1139	our %PID_CB;
…		…
824	or Carp::croak "required option 'pid' is missing";	1166	or Carp::croak "required option 'pid' is missing";
825		1167
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1168	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1169
828	unless ($WNOHANG) {	1170	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1171	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
830	}	1172	}
831		1173
832	unless ($CHLD_W) {	1174	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1175	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# child could be a zombie already, so make at least one round	1176	# child could be a zombie already, so make at least one round
…		…
844	delete $PID_CB{$pid}{$cb};	1186	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1187	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1188
847	undef $CHLD_W unless keys %PID_CB;	1189	undef $CHLD_W unless keys %PID_CB;
848	}	1190	}
		1191
		1192	package AnyEvent::CondVar;
		1193
		1194	our @ISA = AnyEvent::CondVar::Base::;
		1195
		1196	package AnyEvent::CondVar::Base;
		1197
		1198	use overload
		1199	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1200	fallback => 1;
		1201
		1202	sub _send {
		1203	# nop
		1204	}
		1205
		1206	sub send {
		1207	my $cv = shift;
		1208	$cv->{_ae_sent} = [@_];
		1209	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1210	$cv->_send;
		1211	}
		1212
		1213	sub croak {
		1214	$_[0]{_ae_croak} = $_[1];
		1215	$_[0]->send;
		1216	}
		1217
		1218	sub ready {
		1219	$_[0]{_ae_sent}
		1220	}
		1221
		1222	sub _wait {
		1223	AnyEvent->one_event while !$_[0]{_ae_sent};
		1224	}
		1225
		1226	sub recv {
		1227	$_[0]->_wait;
		1228
		1229	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1230	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1231	}
		1232
		1233	sub cb {
		1234	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1235	$_[0]{_ae_cb}
		1236	}
		1237
		1238	sub begin {
		1239	++$_[0]{_ae_counter};
		1240	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1241	}
		1242
		1243	sub end {
		1244	return if --$_[0]{_ae_counter};
		1245	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1246	}
		1247
		1248	# undocumented/compatibility with pre-3.4
		1249	*broadcast = \&send;
		1250	*wait = \&_wait;
		1251
		1252	=head1 ERROR AND EXCEPTION HANDLING
		1253
		1254	In general, AnyEvent does not do any error handling - it relies on the
		1255	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1256	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1257	checking of all AnyEvent methods, however, which is highly useful during
		1258	development.
		1259
		1260	As for exception handling (i.e. runtime errors and exceptions thrown while
		1261	executing a callback), this is not only highly event-loop specific, but
		1262	also not in any way wrapped by this module, as this is the job of the main
		1263	program.
		1264
		1265	The pure perl event loop simply re-throws the exception (usually
		1266	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1267	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1268	so on.
		1269
		1270	=head1 ENVIRONMENT VARIABLES
		1271
		1272	The following environment variables are used by this module or its
		1273	submodules:
		1274
		1275	=over 4
		1276
		1277	=item C<PERL_ANYEVENT_VERBOSE>
		1278
		1279	By default, AnyEvent will be completely silent except in fatal
		1280	conditions. You can set this environment variable to make AnyEvent more
		1281	talkative.
		1282
		1283	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1284	conditions, such as not being able to load the event model specified by
		1285	C<PERL_ANYEVENT_MODEL>.
		1286
		1287	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1288	model it chooses.
		1289
		1290	=item C<PERL_ANYEVENT_STRICT>
		1291
		1292	AnyEvent does not do much argument checking by default, as thorough
		1293	argument checking is very costly. Setting this variable to a true value
		1294	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1295	check the arguments passed to most method calls. If it finds any problems
		1296	it will croak.
		1297
		1298	In other words, enables "strict" mode.
		1299
		1300	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1301	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1302	developing programs can be very useful, however.
		1303
		1304	=item C<PERL_ANYEVENT_MODEL>
		1305
		1306	This can be used to specify the event model to be used by AnyEvent, before
		1307	auto detection and -probing kicks in. It must be a string consisting
		1308	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1309	and the resulting module name is loaded and if the load was successful,
		1310	used as event model. If it fails to load AnyEvent will proceed with
		1311	auto detection and -probing.
		1312
		1313	This functionality might change in future versions.
		1314
		1315	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1316	could start your program like this:
		1317
		1318	PERL_ANYEVENT_MODEL=Perl perl ...
		1319
		1320	=item C<PERL_ANYEVENT_PROTOCOLS>
		1321
		1322	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1323	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1324	of auto probing).
		1325
		1326	Must be set to a comma-separated list of protocols or address families,
		1327	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1328	used, and preference will be given to protocols mentioned earlier in the
		1329	list.
		1330
		1331	This variable can effectively be used for denial-of-service attacks
		1332	against local programs (e.g. when setuid), although the impact is likely
		1333	small, as the program has to handle conenction and other failures anyways.
		1334
		1335	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1336	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1337	- only support IPv4, never try to resolve or contact IPv6
		1338	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1339	IPv6, but prefer IPv6 over IPv4.
		1340
		1341	=item C<PERL_ANYEVENT_EDNS0>
		1342
		1343	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1344	for DNS. This extension is generally useful to reduce DNS traffic, but
		1345	some (broken) firewalls drop such DNS packets, which is why it is off by
		1346	default.
		1347
		1348	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1349	EDNS0 in its DNS requests.
		1350
		1351	=item C<PERL_ANYEVENT_MAX_FORKS>
		1352
		1353	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1354	will create in parallel.
		1355
		1356	=back
849		1357
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1358	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1359
852	This is an advanced topic that you do not normally need to use AnyEvent in	1360	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	1361	a module. This section is only of use to event loop authors who want to
…		…
887		1395
888	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1396	I<rxvt-unicode> also cheats a bit by not providing blocking access to
889	condition variables: code blocking while waiting for a condition will	1397	condition variables: code blocking while waiting for a condition will
890	C<die>. This still works with most modules/usages, and blocking calls must	1398	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.	1399	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		1400
930	=head1 EXAMPLE PROGRAM	1401	=head1 EXAMPLE PROGRAM
931		1402
932	The following program uses an I/O watcher to read data from STDIN, a timer	1403	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	1404	to display a message once per second, and a condition variable to quit the
…		…
942	poll => 'r',	1413	poll => 'r',
943	cb => sub {	1414	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1415	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1416	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1417	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1418	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1419	},
949	);	1420	);
950		1421
951	my $time_watcher; # can only be used once	1422	my $time_watcher; # can only be used once
952		1423
…		…
957	});	1428	});
958	}	1429	}
959		1430
960	new_timer; # create first timer	1431	new_timer; # create first timer
961		1432
962	$cv->wait; # wait until user enters /^q/i	1433	$cv->recv; # wait until user enters /^q/i
963		1434
964	=head1 REAL-WORLD EXAMPLE	1435	=head1 REAL-WORLD EXAMPLE
965		1436
966	Consider the L<Net::FCP> module. It features (among others) the following	1437	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:	1438	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1488	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1489	or die "connection or write error";
1019	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1490	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020		1491
1021	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1492	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:	1493	result and signals any possible waiters that the request has finished:
1023		1494
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1495	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1496
1026	if (end-of-file or data complete) {	1497	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1498	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1499	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1500	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1501	}
1031		1502
1032	The C<result> method, finally, just waits for the finished signal (if the	1503	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	1504	request was already finished, it doesn't wait, of course, and returns the
1034	data:	1505	data:
1035		1506
1036	$txn->{finished}->wait;	1507	$txn->{finished}->recv;
1037	return $txn->{result};	1508	return $txn->{result};
1038		1509
1039	The actual code goes further and collects all errors (C<die>s, exceptions)	1510	The actual code goes further and collects all errors (C<die>s, exceptions)
1040	that occured during request processing. The C<result> method detects	1511	that occurred during request processing. The C<result> method detects
1041	whether an exception as thrown (it is stored inside the $txn object)	1512	whether an exception as thrown (it is stored inside the $txn object)
1042	and just throws the exception, which means connection errors and other	1513	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	1514	problems get reported tot he code that tries to use the result, not in a
1044	random callback.	1515	random callback.
1045		1516
…		…
1076		1547
1077	my $quit = AnyEvent->condvar;	1548	my $quit = AnyEvent->condvar;
1078		1549
1079	$fcp->txn_client_get ($url)->cb (sub {	1550	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1551	...
1081	$quit->broadcast;	1552	$quit->send;
1082	});	1553	});
1083		1554
1084	$quit->wait;	1555	$quit->recv;
1085		1556
1086		1557
1087	=head1 BENCHMARKS	1558	=head1 BENCHMARKS
1088		1559
1089	To give you an idea of the performance and overheads that AnyEvent adds	1560	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1091	of various event loops I prepared some benchmarks.	1562	of various event loops I prepared some benchmarks.
1092		1563
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1564	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1565
1095	Here is a benchmark of various supported event models used natively and	1566	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	1567	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,	1568	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.	1569	which it is), lets them fire exactly once and destroys them again.
1099		1570
1100	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1571	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101	distribution.	1572	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1589	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1590	and memory usage is not included in the figures.
1120		1591
1121	I<invoke> is the time, in microseconds, used to invoke a simple	1592	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	1593	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	1594	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1595	signal the end of this phase.
1125		1596
1126	I<destroy> is the time, in microseconds, that it takes to destroy a single	1597	I<destroy> is the time, in microseconds, that it takes to destroy a single
1127	watcher.	1598	watcher.
1128		1599
1129	=head3 Results	1600	=head3 Results
1130		1601
1131	name watchers bytes create invoke destroy comment	1602	name watchers bytes create invoke destroy comment
1132	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1603	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	1604	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	1605	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	1606	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	1607	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	1608	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	1609	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	1610	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	1611	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	1612	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1142		1613
1143	=head3 Discussion	1614	=head3 Discussion
1144		1615
1145	The benchmark does I<not> measure scalability of the event loop very	1616	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)	1617	well. For example, a select-based event loop (such as the pure perl one)
…		…
1224		1695
1225	=back	1696	=back
1226		1697
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1698	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1699
1229	This benchmark atcually benchmarks the event loop itself. It works by	1700	This benchmark actually benchmarks the event loop itself. It works by
1230	creating a number of "servers": each server consists of a socketpair, a	1701	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	1702	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	1703	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".	1704	watcher reads a byte it will write that byte to a random other "server".
1234		1705
1235	The effect is that there will be a lot of I/O watchers, only part of which	1706	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	1707	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	1708	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	1709	timeout is reset each time something is read because that reflects how
1239	most timeouts work (and puts extra pressure on the event loops).	1710	most timeouts work (and puts extra pressure on the event loops).
1240		1711
1241	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1712	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	1713	(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.	1714	connections, most of which are idle at any one point in time.
1244		1715
1245	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1716	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246	distribution.	1717	distribution.
…		…
1248	=head3 Explanation of the columns	1719	=head3 Explanation of the columns
1249		1720
1250	I<sockets> is the number of sockets, and twice the number of "servers" (as	1721	I<sockets> is the number of sockets, and twice the number of "servers" (as
1251	each server has a read and write socket end).	1722	each server has a read and write socket end).
1252		1723
1253	I<create> is the time it takes to create a socketpair (which is	1724	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.	1725	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255		1726
1256	I<request>, the most important value, is the time it takes to handle a	1727	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	1728	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	1729	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	1802	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1803	them).
1333		1804
1334	EV is again fastest.	1805	EV is again fastest.
1335		1806
1336	Perl again comes second. It is noticably faster than the C-based event	1807	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	1808	loops Event and Glib, although the difference is too small to really
1338	matter.	1809	matter.
1339		1810
1340	POE also performs much better in this case, but is is still far behind the	1811	POE also performs much better in this case, but is is still far behind the
1341	others.	1812	others.
…		…
1346		1817
1347	=item * C-based event loops perform very well with small number of	1818	=item * C-based event loops perform very well with small number of
1348	watchers, as the management overhead dominates.	1819	watchers, as the management overhead dominates.
1349		1820
1350	=back	1821	=back
		1822
		1823
		1824	=head1 SIGNALS
		1825
		1826	AnyEvent currently installs handlers for these signals:
		1827
		1828	=over 4
		1829
		1830	=item SIGCHLD
		1831
		1832	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1833	emulation for event loops that do not support them natively. Also, some
		1834	event loops install a similar handler.
		1835
		1836	=item SIGPIPE
		1837
		1838	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1839	when AnyEvent gets loaded.
		1840
		1841	The rationale for this is that AnyEvent users usually do not really depend
		1842	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1843	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1844	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1845	some random socket.
		1846
		1847	The rationale for installing a no-op handler as opposed to ignoring it is
		1848	that this way, the handler will be restored to defaults on exec.
		1849
		1850	Feel free to install your own handler, or reset it to defaults.
		1851
		1852	=back
		1853
		1854	=cut
		1855
		1856	$SIG{PIPE} = sub { }
		1857	unless defined $SIG{PIPE};
1351		1858
1352		1859
1353	=head1 FORK	1860	=head1 FORK
1354		1861
1355	Most event libraries are not fork-safe. The ones who are usually are	1862	Most event libraries are not fork-safe. The ones who are usually are
…		…
1370	specified in the variable.	1877	specified in the variable.
1371		1878
1372	You can make AnyEvent completely ignore this variable by deleting it	1879	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:	1880	before the first watcher gets created, e.g. with a C<BEGIN> block:
1374		1881
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1882	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		1883
1377	use AnyEvent;	1884	use AnyEvent;
		1885
		1886	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1887	be used to probe what backend is used and gain other information (which is
		1888	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1889	$ENV{PERL_ANYEGENT_STRICT}.
		1890
		1891
		1892	=head1 BUGS
		1893
		1894	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1895	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1896	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1897	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1898	pronounced).
1378		1899
1379		1900
1380	=head1 SEE ALSO	1901	=head1 SEE ALSO
1381		1902
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1903	Utility functions: L<AnyEvent::Util>.
1383	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1904
		1905	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	1906	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		1907
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1908	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1909	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>,	1910	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1911	L<AnyEvent::Impl::POE>.
1390		1912
		1913	Non-blocking file handles, sockets, TCP clients and
		1914	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1915
		1916	Asynchronous DNS: L<AnyEvent::DNS>.
		1917
		1918	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1919
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1920	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		1921
1393		1922
1394	=head1 AUTHOR	1923	=head1 AUTHOR
1395		1924
1396	Marc Lehmann <schmorp@schmorp.de>	1925	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	1926	http://home.schmorp.de/
1398		1927
1399	=cut	1928	=cut
1400		1929
1401	1	1930	1
1402		1931

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