[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.99 by root, Sun Apr 27 17:09:33 2008 UTC vs.
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 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
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		20	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	21	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	22
		23	=head1 INTRODUCTION/TUTORIAL
		24
		25	This manpage is mainly a reference manual. If you are interested
		26	in a tutorial or some gentle introduction, have a look at the
		27	L<AnyEvent::Intro> manpage.
22		28
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		30
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	32	nowadays. So what is different about AnyEvent?
…		…
48	isn't itself. What's worse, all the potential users of your module are	54	isn't itself. What's worse, all the potential users of your module are
49	I<also> forced to use the same event loop you use.	55	I<also> forced to use the same event loop you use.
50		56
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	58	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	59	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,	60	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	61	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	62	event models it supports (including stuff like POE and IO::Async, as long
57	as those use one of the supported event loops. It is trivial to add new	63	as those use one of the supported event loops. It is trivial to add new
58	event loops to AnyEvent, too, so it is future-proof).	64	event loops to AnyEvent, too, so it is future-proof).
59		65
60	In addition to being free of having to use I<the one and only true event	66	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	67	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	68	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	69	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	70	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	71	technically possible.
66		72
		73	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		74	of useful functionality, such as an asynchronous DNS resolver, 100%
		75	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		76	such as Windows) and lots of real-world knowledge and workarounds for
		77	platform bugs and differences.
		78
67	Of course, if you want lots of policy (this can arguably be somewhat	79	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	80	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	81	model, you should I<not> use this module.
70
71	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		82
91	=head1 DESCRIPTION	83	=head1 DESCRIPTION
92		84
93	L<AnyEvent> provides an identical interface to multiple event loops. This	85	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	86	allows module authors to utilise an event loop without forcing module
…		…
98	The interface itself is vaguely similar, but not identical to the L<Event>	90	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	91	module.
100		92
101	During the first call of any watcher-creation method, the module tries	93	During the first call of any watcher-creation method, the module tries
102	to detect the currently loaded event loop by probing whether one of the	94	to detect the currently loaded event loop by probing whether one of the
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	95	following modules is already loaded: L<EV>,
104	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	96	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
105	L<POE>. The first one found is used. If none are found, the module tries	97	L<POE>. The first one found is used. If none are found, the module tries
106	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	98	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
107	adaptor should always succeed) in the order given. The first one that can	99	adaptor should always succeed) in the order given. The first one that can
108	be successfully loaded will be used. If, after this, still none could be	100	be successfully loaded will be used. If, after this, still none could be
…		…
122	starts using it, all bets are off. Maybe you should tell their authors to	114	starts using it, all bets are off. Maybe you should tell their authors to
123	use AnyEvent so their modules work together with others seamlessly...	115	use AnyEvent so their modules work together with others seamlessly...
124		116
125	The pure-perl implementation of AnyEvent is called	117	The pure-perl implementation of AnyEvent is called
126	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	118	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
127	explicitly.	119	explicitly and enjoy the high availability of that event loop :)
128		120
129	=head1 WATCHERS	121	=head1 WATCHERS
130		122
131	AnyEvent has the central concept of a I<watcher>, which is an object that	123	AnyEvent has the central concept of a I<watcher>, which is an object that
132	stores relevant data for each kind of event you are waiting for, such as	124	stores relevant data for each kind of event you are waiting for, such as
133	the callback to call, the filehandle to watch, etc.	125	the callback to call, the file handle to watch, etc.
134		126
135	These watchers are normal Perl objects with normal Perl lifetime. After	127	These watchers are normal Perl objects with normal Perl lifetime. After
136	creating a watcher it will immediately "watch" for events and invoke the	128	creating a watcher it will immediately "watch" for events and invoke the
137	callback when the event occurs (of course, only when the event model	129	callback when the event occurs (of course, only when the event model
138	is in control).	130	is in control).
…		…
146	Many watchers either are used with "recursion" (repeating timers for	138	Many watchers either are used with "recursion" (repeating timers for
147	example), or need to refer to their watcher object in other ways.	139	example), or need to refer to their watcher object in other ways.
148		140
149	An any way to achieve that is this pattern:	141	An any way to achieve that is this pattern:
150		142
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	144	# you can use $w here, for example to undef it
153	undef $w;	145	undef $w;
154	});	146	});
155		147
156	Note that C<my $w; $w => combination. This is necessary because in Perl,	148	Note that C<my $w; $w => combination. This is necessary because in Perl,
157	my variables are only visible after the statement in which they are	149	my variables are only visible after the statement in which they are
158	declared.	150	declared.
159		151
…		…
178		170
179	Some event loops issue spurious readyness notifications, so you should	171	Some event loops issue spurious readyness notifications, so you should
180	always use non-blocking calls when reading/writing from/to your file	172	always use non-blocking calls when reading/writing from/to your file
181	handles.	173	handles.
182		174
183	Example:
184
185	# wait for readability of STDIN, then read a line and disable the watcher	175	Example: wait for readability of STDIN, then read a line and disable the
		176	watcher.
		177
186	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
187	chomp (my $input = <STDIN>);	179	chomp (my $input = <STDIN>);
188	warn "read: $input\n";	180	warn "read: $input\n";
189	undef $w;	181	undef $w;
190	});	182	});
…		…
200		192
201	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
202	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
203	callbacks cannot use arguments passed to time watcher callbacks.	195	callbacks cannot use arguments passed to time watcher callbacks.
204		196
205	The timer callback will be invoked at most once: if you want a repeating	197	The callback will normally be invoked once only. If you specify another
206	timer you have to create a new watcher (this is a limitation by both Tk	198	parameter, C<interval>, as a positive number, then the callback will be
207	and Glib).	199	invoked regularly at that interval (in fractional seconds) after the first
		200	invocation.
208		201
209	Example:	202	The callback will be rescheduled before invoking the callback, but no
		203	attempt is done to avoid timer drift in most backends, so the interval is
		204	only approximate.
210		205
211	# fire an event after 7.7 seconds	206	Example: fire an event after 7.7 seconds.
		207
212	my $w = AnyEvent->timer (after => 7.7, cb => sub {	208	my $w = AnyEvent->timer (after => 7.7, cb => sub {
213	warn "timeout\n";	209	warn "timeout\n";
214	});	210	});
215		211
216	# to cancel the timer:	212	# to cancel the timer:
217	undef $w;	213	undef $w;
218		214
219	Example 2:
220
221	# fire an event after 0.5 seconds, then roughly every second	215	Example 2: fire an event after 0.5 seconds, then roughly every second.
222	my $w;
223		216
224	my $cb = sub {
225	# cancel the old timer while creating a new one
226	$w = AnyEvent->timer (after => 1, cb => $cb);	217	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		218	warn "timeout\n";
227	};	219	};
228
229	# start the "loop" by creating the first watcher
230	$w = AnyEvent->timer (after => 0.5, cb => $cb);
231		220
232	=head3 TIMING ISSUES	221	=head3 TIMING ISSUES
233		222
234	There are two ways to handle timers: based on real time (relative, "fire	223	There are two ways to handle timers: based on real time (relative, "fire
235	in 10 seconds") and based on wallclock time (absolute, "fire at 12	224	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
247	timers.	236	timers.
248		237
249	AnyEvent always prefers relative timers, if available, matching the	238	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	239	AnyEvent API.
251		240
		241	AnyEvent has two additional methods that return the "current time":
		242
		243	=over 4
		244
		245	=item AnyEvent->time
		246
		247	This returns the "current wallclock time" as a fractional number of
		248	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		249	return, and the result is guaranteed to be compatible with those).
		250
		251	It progresses independently of any event loop processing, i.e. each call
		252	will check the system clock, which usually gets updated frequently.
		253
		254	=item AnyEvent->now
		255
		256	This also returns the "current wallclock time", but unlike C<time>, above,
		257	this value might change only once per event loop iteration, depending on
		258	the event loop (most return the same time as C<time>, above). This is the
		259	time that AnyEvent's timers get scheduled against.
		260
		261	I<In almost all cases (in all cases if you don't care), this is the
		262	function to call when you want to know the current time.>
		263
		264	This function is also often faster then C<< AnyEvent->time >>, and
		265	thus the preferred method if you want some timestamp (for example,
		266	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		267
		268	The rest of this section is only of relevance if you try to be very exact
		269	with your timing, you can skip it without bad conscience.
		270
		271	For a practical example of when these times differ, consider L<Event::Lib>
		272	and L<EV> and the following set-up:
		273
		274	The event loop is running and has just invoked one of your callback at
		275	time=500 (assume no other callbacks delay processing). In your callback,
		276	you wait a second by executing C<sleep 1> (blocking the process for a
		277	second) and then (at time=501) you create a relative timer that fires
		278	after three seconds.
		279
		280	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		281	both return C<501>, because that is the current time, and the timer will
		282	be scheduled to fire at time=504 (C<501> + C<3>).
		283
		284	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		285	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		286	last event processing phase started. With L<EV>, your timer gets scheduled
		287	to run at time=503 (C<500> + C<3>).
		288
		289	In one sense, L<Event::Lib> is more exact, as it uses the current time
		290	regardless of any delays introduced by event processing. However, most
		291	callbacks do not expect large delays in processing, so this causes a
		292	higher drift (and a lot more system calls to get the current time).
		293
		294	In another sense, L<EV> is more exact, as your timer will be scheduled at
		295	the same time, regardless of how long event processing actually took.
		296
		297	In either case, if you care (and in most cases, you don't), then you
		298	can get whatever behaviour you want with any event loop, by taking the
		299	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		300	account.
		301
		302	=back
		303
252	=head2 SIGNAL WATCHERS	304	=head2 SIGNAL WATCHERS
253		305
254	You can watch for signals using a signal watcher, C<signal> is the signal	306	You can watch for signals using a signal watcher, C<signal> is the signal
255	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	307	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
256	be invoked whenever a signal occurs.	308	be invoked whenever a signal occurs.
257		309
258	Although the callback might get passed parameters, their value and	310	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	311	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	312	callbacks cannot use arguments passed to signal watcher callbacks.
261		313
262	Multiple signal occurances can be clumped together into one callback	314	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	315	invocation, and callback invocation will be synchronous. Synchronous means
264	that it might take a while until the signal gets handled by the process,	316	that it might take a while until the signal gets handled by the process,
265	but it is guarenteed not to interrupt any other callbacks.	317	but it is guaranteed not to interrupt any other callbacks.
266		318
267	The main advantage of using these watchers is that you can share a signal	319	The main advantage of using these watchers is that you can share a signal
268	between multiple watchers.	320	between multiple watchers.
269		321
270	This watcher might use C<%SIG>, so programs overwriting those signals	322	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
297	AnyEvent program, you I<have> to create at least one watcher before you	349	AnyEvent program, you I<have> to create at least one watcher before you
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	350	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
299		351
300	Example: fork a process and wait for it	352	Example: fork a process and wait for it
301		353
302	my $done = AnyEvent->condvar;	354	my $done = AnyEvent->condvar;
303		355
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	356	my $pid = fork or exit 5;
307		357
308	my $w = AnyEvent->child (	358	my $w = AnyEvent->child (
309	pid => $pid,	359	pid => $pid,
310	cb => sub {	360	cb => sub {
311	my ($pid, $status) = @_;	361	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	362	warn "pid $pid exited with status $status";
313	$done->broadcast;	363	$done->send;
314	},	364	},
315	);	365	);
316		366
317	# do something else, then wait for process exit	367	# do something else, then wait for process exit
318	$done->wait;	368	$done->recv;
319		369
320	=head2 CONDITION VARIABLES	370	=head2 CONDITION VARIABLES
321		371
		372	If you are familiar with some event loops you will know that all of them
		373	require you to run some blocking "loop", "run" or similar function that
		374	will actively watch for new events and call your callbacks.
		375
		376	AnyEvent is different, it expects somebody else to run the event loop and
		377	will only block when necessary (usually when told by the user).
		378
		379	The instrument to do that is called a "condition variable", so called
		380	because they represent a condition that must become true.
		381
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	382	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	383	>> method, usually without arguments. The only argument pair allowed is
		384	C<cb>, which specifies a callback to be called when the condition variable
		385	becomes true.
324		386
325	A condition variable waits for a condition - precisely that the C<<	387	After creation, the condition variable is "false" until it becomes "true"
326	->broadcast >> method has been called.	388	by calling the C<send> method (or calling the condition variable as if it
		389	were a callback, read about the caveats in the description for the C<<
		390	->send >> method).
327		391
328	They are very useful to signal that a condition has been fulfilled, for	392	Condition variables are similar to callbacks, except that you can
		393	optionally wait for them. They can also be called merge points - points
		394	in time where multiple outstanding events have been processed. And yet
		395	another way to call them is transactions - each condition variable can be
		396	used to represent a transaction, which finishes at some point and delivers
		397	a result.
		398
		399	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	400	for example, if you write a module that does asynchronous http requests,
330	then a condition variable would be the ideal candidate to signal the	401	then a condition variable would be the ideal candidate to signal the
331	availability of results.	402	availability of results. The user can either act when the callback is
		403	called or can synchronously C<< ->recv >> for the results.
332		404
333	You can also use condition variables to block your main program until	405	You can also use them to simulate traditional event loops - for example,
334	an event occurs - for example, you could C<< ->wait >> in your main	406	you can block your main program until an event occurs - for example, you
335	program until the user clicks the Quit button in your app, which would C<<	407	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	408	button of your app, which would C<< ->send >> the "quit" event.
337		409
338	Note that condition variables recurse into the event loop - if you have	410	Note that condition variables recurse into the event loop - if you have
339	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	411	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	412	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,	413	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	414	as this asks for trouble.
343		415
344	This object has two methods:	416	Condition variables are represented by hash refs in perl, and the keys
		417	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		418	easy (it is often useful to build your own transaction class on top of
		419	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		420	it's C<new> method in your own C<new> method.
		421
		422	There are two "sides" to a condition variable - the "producer side" which
		423	eventually calls C<< -> send >>, and the "consumer side", which waits
		424	for the send to occur.
		425
		426	Example: wait for a timer.
		427
		428	# wait till the result is ready
		429	my $result_ready = AnyEvent->condvar;
		430
		431	# do something such as adding a timer
		432	# or socket watcher the calls $result_ready->send
		433	# when the "result" is ready.
		434	# in this case, we simply use a timer:
		435	my $w = AnyEvent->timer (
		436	after => 1,
		437	cb => sub { $result_ready->send },
		438	);
		439
		440	# this "blocks" (while handling events) till the callback
		441	# calls send
		442	$result_ready->recv;
		443
		444	Example: wait for a timer, but take advantage of the fact that
		445	condition variables are also code references.
		446
		447	my $done = AnyEvent->condvar;
		448	my $delay = AnyEvent->timer (after => 5, cb => $done);
		449	$done->recv;
		450
		451	=head3 METHODS FOR PRODUCERS
		452
		453	These methods should only be used by the producing side, i.e. the
		454	code/module that eventually sends the signal. Note that it is also
		455	the producer side which creates the condvar in most cases, but it isn't
		456	uncommon for the consumer to create it as well.
345		457
346	=over 4	458	=over 4
347		459
		460	=item $cv->send (...)
		461
		462	Flag the condition as ready - a running C<< ->recv >> and all further
		463	calls to C<recv> will (eventually) return after this method has been
		464	called. If nobody is waiting the send will be remembered.
		465
		466	If a callback has been set on the condition variable, it is called
		467	immediately from within send.
		468
		469	Any arguments passed to the C<send> call will be returned by all
		470	future C<< ->recv >> calls.
		471
		472	Condition variables are overloaded so one can call them directly
		473	(as a code reference). Calling them directly is the same as calling
		474	C<send>. Note, however, that many C-based event loops do not handle
		475	overloading, so as tempting as it may be, passing a condition variable
		476	instead of a callback does not work. Both the pure perl and EV loops
		477	support overloading, however, as well as all functions that use perl to
		478	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		479	example).
		480
		481	=item $cv->croak ($error)
		482
		483	Similar to send, but causes all call's to C<< ->recv >> to invoke
		484	C<Carp::croak> with the given error message/object/scalar.
		485
		486	This can be used to signal any errors to the condition variable
		487	user/consumer.
		488
		489	=item $cv->begin ([group callback])
		490
348	=item $cv->wait	491	=item $cv->end
349		492
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	493	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		494
		495	These two methods can be used to combine many transactions/events into
		496	one. For example, a function that pings many hosts in parallel might want
		497	to use a condition variable for the whole process.
		498
		499	Every call to C<< ->begin >> will increment a counter, and every call to
		500	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		501	>>, the (last) callback passed to C<begin> will be executed. That callback
		502	is I<supposed> to call C<< ->send >>, but that is not required. If no
		503	callback was set, C<send> will be called without any arguments.
		504
		505	Let's clarify this with the ping example:
		506
		507	my $cv = AnyEvent->condvar;
		508
		509	my %result;
		510	$cv->begin (sub { $cv->send (\%result) });
		511
		512	for my $host (@list_of_hosts) {
		513	$cv->begin;
		514	ping_host_then_call_callback $host, sub {
		515	$result{$host} = ...;
		516	$cv->end;
		517	};
		518	}
		519
		520	$cv->end;
		521
		522	This code fragment supposedly pings a number of hosts and calls
		523	C<send> after results for all then have have been gathered - in any
		524	order. To achieve this, the code issues a call to C<begin> when it starts
		525	each ping request and calls C<end> when it has received some result for
		526	it. Since C<begin> and C<end> only maintain a counter, the order in which
		527	results arrive is not relevant.
		528
		529	There is an additional bracketing call to C<begin> and C<end> outside the
		530	loop, which serves two important purposes: first, it sets the callback
		531	to be called once the counter reaches C<0>, and second, it ensures that
		532	C<send> is called even when C<no> hosts are being pinged (the loop
		533	doesn't execute once).
		534
		535	This is the general pattern when you "fan out" into multiple subrequests:
		536	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		537	is called at least once, and then, for each subrequest you start, call
		538	C<begin> and for each subrequest you finish, call C<end>.
		539
		540	=back
		541
		542	=head3 METHODS FOR CONSUMERS
		543
		544	These methods should only be used by the consuming side, i.e. the
		545	code awaits the condition.
		546
		547	=over 4
		548
		549	=item $cv->recv
		550
		551	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	552	>> methods have been called on c<$cv>, while servicing other watchers
		553	normally.
352		554
353	You can only wait once on a condition - additional calls will return	555	You can only wait once on a condition - additional calls are valid but
354	immediately.	556	will return immediately.
		557
		558	If an error condition has been set by calling C<< ->croak >>, then this
		559	function will call C<croak>.
		560
		561	In list context, all parameters passed to C<send> will be returned,
		562	in scalar context only the first one will be returned.
355		563
356	Not all event models support a blocking wait - some die in that case	564	Not all event models support a blocking wait - some die in that case
357	(programs might want to do that to stay interactive), so I<if you are	565	(programs might want to do that to stay interactive), so I<if you are
358	using this from a module, never require a blocking wait>, but let the	566	using this from a module, never require a blocking wait>, but let the
359	caller decide whether the call will block or not (for example, by coupling	567	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting	568	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,	569	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).	570	while still supporting blocking waits if the caller so desires).
363		571
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot	572	Another reason I<never> to C<< ->recv >> in a module is that you cannot
365	sensibly have two C<< ->wait >>'s in parallel, as that would require	573	sensibly have two C<< ->recv >>'s in parallel, as that would require
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	574	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	575	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		576
371	=item $cv->broadcast	577	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		578	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		579	versions and also integrates coroutines into AnyEvent, making blocking
		580	C<< ->recv >> calls perfectly safe as long as they are done from another
		581	coroutine (one that doesn't run the event loop).
372		582
373	Flag the condition as ready - a running C<< ->wait >> and all further	583	You can ensure that C<< -recv >> never blocks by setting a callback and
374	calls to C<wait> will (eventually) return after this method has been	584	only calling C<< ->recv >> from within that callback (or at a later
375	called. If nobody is waiting the broadcast will be remembered..	585	time). This will work even when the event loop does not support blocking
		586	waits otherwise.
		587
		588	=item $bool = $cv->ready
		589
		590	Returns true when the condition is "true", i.e. whether C<send> or
		591	C<croak> have been called.
		592
		593	=item $cb = $cv->cb ([new callback])
		594
		595	This is a mutator function that returns the callback set and optionally
		596	replaces it before doing so.
		597
		598	The callback will be called when the condition becomes "true", i.e. when
		599	C<send> or C<croak> are called, with the only argument being the condition
		600	variable itself. Calling C<recv> inside the callback or at any later time
		601	is guaranteed not to block.
376		602
377	=back	603	=back
378
379	Example:
380
381	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;
383
384	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392
393	# this "blocks" (while handling events) till the watcher
394	# calls broadcast
395	$result_ready->wait;
396		604
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	605	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		606
399	=over 4	607	=over 4
400		608
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	614	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	615	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		616
409	The known classes so far are:	617	The known classes so far are:
410		618
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	619	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	620	AnyEvent::Impl::Event based on Event, second best choice.
		621	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	622	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	623	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	624	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	625	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	626	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		627
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	640	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	641	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	642	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	643	runtime.
438		644
		645	=item $guard = AnyEvent::post_detect { BLOCK }
		646
		647	Arranges for the code block to be executed as soon as the event model is
		648	autodetected (or immediately if this has already happened).
		649
		650	If called in scalar or list context, then it creates and returns an object
		651	that automatically removes the callback again when it is destroyed. See
		652	L<Coro::BDB> for a case where this is useful.
		653
		654	=item @AnyEvent::post_detect
		655
		656	If there are any code references in this array (you can C<push> to it
		657	before or after loading AnyEvent), then they will called directly after
		658	the event loop has been chosen.
		659
		660	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		661	if it contains a true value then the event loop has already been detected,
		662	and the array will be ignored.
		663
		664	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		665
439	=back	666	=back
440		667
441	=head1 WHAT TO DO IN A MODULE	668	=head1 WHAT TO DO IN A MODULE
442		669
443	As a module author, you should C<use AnyEvent> and call AnyEvent methods	670	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	673	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	674	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	675	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	676	to load the event module first.
450		677
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	678	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	679	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	680	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	681	events is to stay interactive.
455		682
456	It is fine, however, to call C<< ->wait >> when the user of your module	683	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	684	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	685	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	686	freely, as the user of your module knows what she is doing. always).
460		687
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	688	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		689
463	There will always be a single main program - the only place that should	690	There will always be a single main program - the only place that should
…		…
465		692
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	693	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	694	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	695	decide which implementation to chose if some module relies on it.
469		696
470	If the main program relies on a specific event model. For example, in	697	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	698	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	699	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	700	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	701	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	702	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	703	might chose the wrong one unless you load the correct one yourself.
477		704
478	You can chose to use a rather inefficient pure-perl implementation by	705	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	706	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	707	everywhere, but letting AnyEvent chose the model is generally better.
		708
		709	=head2 MAINLOOP EMULATION
		710
		711	Sometimes (often for short test scripts, or even standalone programs who
		712	only want to use AnyEvent), you do not want to run a specific event loop.
		713
		714	In that case, you can use a condition variable like this:
		715
		716	AnyEvent->condvar->recv;
		717
		718	This has the effect of entering the event loop and looping forever.
		719
		720	Note that usually your program has some exit condition, in which case
		721	it is better to use the "traditional" approach of storing a condition
		722	variable somewhere, waiting for it, and sending it when the program should
		723	exit cleanly.
		724
		725
		726	=head1 OTHER MODULES
		727
		728	The following is a non-exhaustive list of additional modules that use
		729	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		730	in the same program. Some of the modules come with AnyEvent, some are
		731	available via CPAN.
		732
		733	=over 4
		734
		735	=item L<AnyEvent::Util>
		736
		737	Contains various utility functions that replace often-used but blocking
		738	functions such as C<inet_aton> by event-/callback-based versions.
		739
		740	=item L<AnyEvent::Socket>
		741
		742	Provides various utility functions for (internet protocol) sockets,
		743	addresses and name resolution. Also functions to create non-blocking tcp
		744	connections or tcp servers, with IPv6 and SRV record support and more.
		745
		746	=item L<AnyEvent::Handle>
		747
		748	Provide read and write buffers, manages watchers for reads and writes,
		749	supports raw and formatted I/O, I/O queued and fully transparent and
		750	non-blocking SSL/TLS.
		751
		752	=item L<AnyEvent::DNS>
		753
		754	Provides rich asynchronous DNS resolver capabilities.
		755
		756	=item L<AnyEvent::HTTP>
		757
		758	A simple-to-use HTTP library that is capable of making a lot of concurrent
		759	HTTP requests.
		760
		761	=item L<AnyEvent::HTTPD>
		762
		763	Provides a simple web application server framework.
		764
		765	=item L<AnyEvent::FastPing>
		766
		767	The fastest ping in the west.
		768
		769	=item L<AnyEvent::DBI>
		770
		771	Executes L<DBI> requests asynchronously in a proxy process.
		772
		773	=item L<AnyEvent::AIO>
		774
		775	Truly asynchronous I/O, should be in the toolbox of every event
		776	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		777	together.
		778
		779	=item L<AnyEvent::BDB>
		780
		781	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		782	L<BDB> and AnyEvent together.
		783
		784	=item L<AnyEvent::GPSD>
		785
		786	A non-blocking interface to gpsd, a daemon delivering GPS information.
		787
		788	=item L<AnyEvent::IGS>
		789
		790	A non-blocking interface to the Internet Go Server protocol (used by
		791	L<App::IGS>).
		792
		793	=item L<Net::IRC3>
		794
		795	AnyEvent based IRC client module family.
		796
		797	=item L<Net::XMPP2>
		798
		799	AnyEvent based XMPP (Jabber protocol) module family.
		800
		801	=item L<Net::FCP>
		802
		803	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		804	of AnyEvent.
		805
		806	=item L<Event::ExecFlow>
		807
		808	High level API for event-based execution flow control.
		809
		810	=item L<Coro>
		811
		812	Has special support for AnyEvent via L<Coro::AnyEvent>.
		813
		814	=item L<IO::Lambda>
		815
		816	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		817
		818	=back
481		819
482	=cut	820	=cut
483		821
484	package AnyEvent;	822	package AnyEvent;
485		823
486	no warnings;	824	no warnings;
487	use strict;	825	use strict;
488		826
489	use Carp;	827	use Carp;
490		828
491	our $VERSION = '3.3';	829	our $VERSION = 4.2;
492	our $MODEL;	830	our $MODEL;
493		831
494	our $AUTOLOAD;	832	our $AUTOLOAD;
495	our @ISA;	833	our @ISA;
496		834
		835	our @REGISTRY;
		836
		837	our $WIN32;
		838
		839	BEGIN {
		840	my $win32 = ! ! ($^O =~ /mswin32/i);
		841	eval "sub WIN32(){ $win32 }";
		842	}
		843
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	844	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498		845
499	our @REGISTRY;	846	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		847
		848	{
		849	my $idx;
		850	$PROTOCOL{$_} = ++$idx
		851	for reverse split /\s,\s/,
		852	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		853	}
500		854
501	my @models = (	855	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	856	[EV:: => AnyEvent::Impl::EV::],
505	[Event:: => AnyEvent::Impl::Event::],	857	[Event:: => AnyEvent::Impl::Event::],
506	[Glib:: => AnyEvent::Impl::Glib::],
507	[Tk:: => AnyEvent::Impl::Tk::],
508	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	858	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	859	# everything below here will not be autoprobed
		860	# as the pureperl backend should work everywhere
		861	# and is usually faster
		862	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		863	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	864	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	865	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	866	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		867	[Wx:: => AnyEvent::Impl::POE::],
		868	[Prima:: => AnyEvent::Impl::POE::],
515	);	869	);
516		870
517	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	871	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		872
		873	our @post_detect;
		874
		875	sub post_detect(&) {
		876	my ($cb) = @_;
		877
		878	if ($MODEL) {
		879	$cb->();
		880
		881	1
		882	} else {
		883	push @post_detect, $cb;
		884
		885	defined wantarray
		886	? bless \$cb, "AnyEvent::Util::PostDetect"
		887	: ()
		888	}
		889	}
		890
		891	sub AnyEvent::Util::PostDetect::DESTROY {
		892	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		893	}
518		894
519	sub detect() {	895	sub detect() {
520	unless ($MODEL) {	896	unless ($MODEL) {
521	no strict 'refs';	897	no strict 'refs';
		898	local $SIG{__DIE__};
522		899
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	900	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
524	my $model = "AnyEvent::Impl::$1";	901	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	902	if (eval "require $model") {
526	$MODEL = $model;	903	$MODEL = $model;
…		…
556	last;	933	last;
557	}	934	}
558	}	935	}
559		936
560	$MODEL	937	$MODEL
561	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.";	938	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
562	}	939	}
563	}	940	}
564		941
565	unshift @ISA, $MODEL;	942	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		944
		945	(shift @post_detect)->() while @post_detect;
567	}	946	}
568		947
569	$MODEL	948	$MODEL
570	}	949	}
571		950
…		…
581	$class->$func (@_);	960	$class->$func (@_);
582	}	961	}
583		962
584	package AnyEvent::Base;	963	package AnyEvent::Base;
585		964
		965	# default implementation for now and time
		966
		967	use Time::HiRes ();
		968
		969	sub time { Time::HiRes::time }
		970	sub now { Time::HiRes::time }
		971
586	# default implementation for ->condvar, ->wait, ->broadcast	972	# default implementation for ->condvar
587		973
588	sub condvar {	974	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	975	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
590	}
591
592	sub AnyEvent::Base::CondVar::broadcast {
593	${$_[0]}++;
594	}
595
596	sub AnyEvent::Base::CondVar::wait {
597	AnyEvent->one_event while !${$_[0]};
598	}	976	}
599		977
600	# default implementation for ->signal	978	# default implementation for ->signal
601		979
602	our %SIG_CB;	980	our %SIG_CB;
…		…
618	sub AnyEvent::Base::Signal::DESTROY {	996	sub AnyEvent::Base::Signal::DESTROY {
619	my ($signal, $cb) = @{$_[0]};	997	my ($signal, $cb) = @{$_[0]};
620		998
621	delete $SIG_CB{$signal}{$cb};	999	delete $SIG_CB{$signal}{$cb};
622		1000
623	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1001	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
624	}	1002	}
625		1003
626	# default implementation for ->child	1004	# default implementation for ->child
627		1005
628	our %PID_CB;	1006	our %PID_CB;
…		…
655	or Carp::croak "required option 'pid' is missing";	1033	or Carp::croak "required option 'pid' is missing";
656		1034
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1035	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1036
659	unless ($WNOHANG) {	1037	unless ($WNOHANG) {
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1038	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
661	}	1039	}
662		1040
663	unless ($CHLD_W) {	1041	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1042	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
665	# child could be a zombie already, so make at least one round	1043	# child could be a zombie already, so make at least one round
…		…
675	delete $PID_CB{$pid}{$cb};	1053	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1054	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1055
678	undef $CHLD_W unless keys %PID_CB;	1056	undef $CHLD_W unless keys %PID_CB;
679	}	1057	}
		1058
		1059	package AnyEvent::CondVar;
		1060
		1061	our @ISA = AnyEvent::CondVar::Base::;
		1062
		1063	package AnyEvent::CondVar::Base;
		1064
		1065	use overload
		1066	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1067	fallback => 1;
		1068
		1069	sub _send {
		1070	# nop
		1071	}
		1072
		1073	sub send {
		1074	my $cv = shift;
		1075	$cv->{_ae_sent} = [@_];
		1076	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1077	$cv->_send;
		1078	}
		1079
		1080	sub croak {
		1081	$_[0]{_ae_croak} = $_[1];
		1082	$_[0]->send;
		1083	}
		1084
		1085	sub ready {
		1086	$_[0]{_ae_sent}
		1087	}
		1088
		1089	sub _wait {
		1090	AnyEvent->one_event while !$_[0]{_ae_sent};
		1091	}
		1092
		1093	sub recv {
		1094	$_[0]->_wait;
		1095
		1096	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1097	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1098	}
		1099
		1100	sub cb {
		1101	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1102	$_[0]{_ae_cb}
		1103	}
		1104
		1105	sub begin {
		1106	++$_[0]{_ae_counter};
		1107	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1108	}
		1109
		1110	sub end {
		1111	return if --$_[0]{_ae_counter};
		1112	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1113	}
		1114
		1115	# undocumented/compatibility with pre-3.4
		1116	*broadcast = \&send;
		1117	*wait = \&_wait;
680		1118
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1119	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1120
683	This is an advanced topic that you do not normally need to use AnyEvent in	1121	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1122	a module. This section is only of use to event loop authors who want to
…		…
741	model it chooses.	1179	model it chooses.
742		1180
743	=item C<PERL_ANYEVENT_MODEL>	1181	=item C<PERL_ANYEVENT_MODEL>
744		1182
745	This can be used to specify the event model to be used by AnyEvent, before	1183	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting	1184	auto detection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1185	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,	1186	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with	1187	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.	1188	auto detection and -probing.
751		1189
752	This functionality might change in future versions.	1190	This functionality might change in future versions.
753		1191
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1192	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:	1193	could start your program like this:
756		1194
757	PERL_ANYEVENT_MODEL=Perl perl ...	1195	PERL_ANYEVENT_MODEL=Perl perl ...
		1196
		1197	=item C<PERL_ANYEVENT_PROTOCOLS>
		1198
		1199	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1200	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1201	of auto probing).
		1202
		1203	Must be set to a comma-separated list of protocols or address families,
		1204	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1205	used, and preference will be given to protocols mentioned earlier in the
		1206	list.
		1207
		1208	This variable can effectively be used for denial-of-service attacks
		1209	against local programs (e.g. when setuid), although the impact is likely
		1210	small, as the program has to handle connection errors already-
		1211
		1212	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1213	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1214	- only support IPv4, never try to resolve or contact IPv6
		1215	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1216	IPv6, but prefer IPv6 over IPv4.
		1217
		1218	=item C<PERL_ANYEVENT_EDNS0>
		1219
		1220	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1221	for DNS. This extension is generally useful to reduce DNS traffic, but
		1222	some (broken) firewalls drop such DNS packets, which is why it is off by
		1223	default.
		1224
		1225	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1226	EDNS0 in its DNS requests.
		1227
		1228	=item C<PERL_ANYEVENT_MAX_FORKS>
		1229
		1230	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1231	will create in parallel.
758		1232
759	=back	1233	=back
760		1234
761	=head1 EXAMPLE PROGRAM	1235	=head1 EXAMPLE PROGRAM
762		1236
…		…
773	poll => 'r',	1247	poll => 'r',
774	cb => sub {	1248	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1249	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1250	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1251	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1252	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1253	},
780	);	1254	);
781		1255
782	my $time_watcher; # can only be used once	1256	my $time_watcher; # can only be used once
783		1257
…		…
788	});	1262	});
789	}	1263	}
790		1264
791	new_timer; # create first timer	1265	new_timer; # create first timer
792		1266
793	$cv->wait; # wait until user enters /^q/i	1267	$cv->recv; # wait until user enters /^q/i
794		1268
795	=head1 REAL-WORLD EXAMPLE	1269	=head1 REAL-WORLD EXAMPLE
796		1270
797	Consider the L<Net::FCP> module. It features (among others) the following	1271	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	1272	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	1322	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	1323	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1324	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		1325
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1326	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	1327	result and signals any possible waiters that the request has finished:
854		1328
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1329	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		1330
857	if (end-of-file or data complete) {	1331	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	1332	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	1333	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1334	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	1335	}
862		1336
863	The C<result> method, finally, just waits for the finished signal (if the	1337	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	1338	request was already finished, it doesn't wait, of course, and returns the
865	data:	1339	data:
866		1340
867	$txn->{finished}->wait;	1341	$txn->{finished}->recv;
868	return $txn->{result};	1342	return $txn->{result};
869		1343
870	The actual code goes further and collects all errors (C<die>s, exceptions)	1344	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	1345	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	1346	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	1347	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	1348	problems get reported tot he code that tries to use the result, not in a
875	random callback.	1349	random callback.
876		1350
…		…
907		1381
908	my $quit = AnyEvent->condvar;	1382	my $quit = AnyEvent->condvar;
909		1383
910	$fcp->txn_client_get ($url)->cb (sub {	1384	$fcp->txn_client_get ($url)->cb (sub {
911	...	1385	...
912	$quit->broadcast;	1386	$quit->send;
913	});	1387	});
914		1388
915	$quit->wait;	1389	$quit->recv;
916		1390
917		1391
918	=head1 BENCHMARKS	1392	=head1 BENCHMARKS
919		1393
920	To give you an idea of the performance and overheads that AnyEvent adds	1394	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	1396	of various event loops I prepared some benchmarks.
923		1397
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	1398	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		1399
926	Here is a benchmark of various supported event models used natively and	1400	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	1401	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1402	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	1403	which it is), lets them fire exactly once and destroys them again.
930		1404
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1405	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	1406	distribution.
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	1423	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	1424	and memory usage is not included in the figures.
951		1425
952	I<invoke> is the time, in microseconds, used to invoke a simple	1426	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	1427	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1428	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	1429	signal the end of this phase.
956		1430
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	1431	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	1432	watcher.
959		1433
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	1493	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	1494	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	1495	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	1496	above).
1023		1497
1024	C<POE>, regardless of underlying event loop (whether using its pure	1498	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	1499	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	1500	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	1501	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	1502	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	1503	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1504	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1505	implementation.
		1506
1031	implementation. The design of the POE adaptor class in AnyEvent can not	1507	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	1508	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	1509	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1510	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1511	using multiple sessions is not a good approach, especially regarding
		1512	memory usage, even the author of POE could not come up with a faster
		1513	design).
1035		1514
1036	=head3 Summary	1515	=head3 Summary
1037		1516
1038	=over 4	1517	=over 4
1039		1518
…		…
1050		1529
1051	=back	1530	=back
1052		1531
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	1532	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		1533
1055	This benchmark atcually benchmarks the event loop itself. It works by	1534	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	1535	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	1536	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	1537	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	1538	watcher reads a byte it will write that byte to a random other "server".
1060		1539
1061	The effect is that there will be a lot of I/O watchers, only part of which	1540	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	1541	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	1542	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	1543	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	1544	most timeouts work (and puts extra pressure on the event loops).
1066		1545
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1546	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	1547	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	1548	connections, most of which are idle at any one point in time.
1070		1549
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1550	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	1551	distribution.
…		…
1074	=head3 Explanation of the columns	1553	=head3 Explanation of the columns
1075		1554
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	1555	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	1556	each server has a read and write socket end).
1078		1557
1079	I<create> is the time it takes to create a socketpair (which is	1558	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1559	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		1560
1082	I<request>, the most important value, is the time it takes to handle a	1561	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	1562	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	1563	it to another server. This includes deleting the old timeout and creating
…		…
1118		1597
1119	=head3 Summary	1598	=head3 Summary
1120		1599
1121	=over 4	1600	=over 4
1122		1601
1123	=item * The pure perl implementation performs extremely well, considering	1602	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		1603
1126	=item * Avoid Glib or POE in large projects where performance matters.	1604	=item * Avoid Glib or POE in large projects where performance matters.
1127		1605
1128	=back	1606	=back
1129		1607
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	1636	speed most when you have lots of watchers, not when you only have a few of
1159	them).	1637	them).
1160		1638
1161	EV is again fastest.	1639	EV is again fastest.
1162		1640
1163	The C-based event loops Event and Glib come in second this time, as the	1641	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	1642	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	1643	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		1644
1170	POE also performs much better in this case, but is is still far behind the	1645	POE also performs much better in this case, but is is still far behind the
1171	others.	1646	others.
1172		1647
1173	=head3 Summary	1648	=head3 Summary
…		…
1181		1656
1182		1657
1183	=head1 FORK	1658	=head1 FORK
1184		1659
1185	Most event libraries are not fork-safe. The ones who are usually are	1660	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	1661	because they rely on inefficient but fork-safe C<select> or C<poll>
		1662	calls. Only L<EV> is fully fork-aware.
1187		1663
1188	If you have to fork, you must either do so I<before> creating your first	1664	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	1665	watcher OR you must not use AnyEvent at all in the child.
1190		1666
1191		1667
…		…
1199	specified in the variable.	1675	specified in the variable.
1200		1676
1201	You can make AnyEvent completely ignore this variable by deleting it	1677	You can make AnyEvent completely ignore this variable by deleting it
1202	before the first watcher gets created, e.g. with a C<BEGIN> block:	1678	before the first watcher gets created, e.g. with a C<BEGIN> block:
1203		1679
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1680	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		1681
1206	use AnyEvent;	1682	use AnyEvent;
		1683
		1684	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1685	be used to probe what backend is used and gain other information (which is
		1686	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1687
		1688
		1689	=head1 BUGS
		1690
		1691	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1692	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1693	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1694	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1695	pronounced).
1207		1696
1208		1697
1209	=head1 SEE ALSO	1698	=head1 SEE ALSO
1210		1699
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1700	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1701
		1702	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	1703	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		1704
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1705	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1706	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1707	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1708	L<AnyEvent::Impl::POE>.
1219		1709
		1710	Non-blocking file handles, sockets, TCP clients and
		1711	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1712
		1713	Asynchronous DNS: L<AnyEvent::DNS>.
		1714
		1715	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1716
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1717	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1221		1718
1222		1719
1223	=head1 AUTHOR	1720	=head1 AUTHOR
1224		1721
1225	Marc Lehmann <schmorp@schmorp.de>	1722	Marc Lehmann <schmorp@schmorp.de>
1226	http://home.schmorp.de/	1723	http://home.schmorp.de/
1227		1724
1228	=cut	1725	=cut
1229		1726
1230	1	1727	1
1231		1728

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.99 by root, Sun Apr 27 17:09:33 2008 UTC vs. Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.99 by root, Sun Apr 27 17:09:33 2008 UTC vs.
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC