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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.108 by root, Sat May 10 00:22:02 2008 UTC vs.
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC

…		…
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 ->send	21	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->send; # 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		82
71	=head1 DESCRIPTION	83	=head1 DESCRIPTION
72		84
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	115	use AnyEvent so their modules work together with others seamlessly...
104		116
105	The pure-perl implementation of AnyEvent is called	117	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	119	explicitly and enjoy the high availability of that event loop :)
108		120
109	=head1 WATCHERS	121	=head1 WATCHERS
110		122
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	125	the callback to call, the file handle to watch, etc.
114		126
115	These watchers are normal Perl objects with normal Perl lifetime. After	127	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	130	is in control).
…		…
126	Many watchers either are used with "recursion" (repeating timers for	138	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		140
129	An any way to achieve that is this pattern:	141	An any way to achieve that is this pattern:
130		142
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	144	# you can use $w here, for example to undef it
133	undef $w;	145	undef $w;
134	});	146	});
135		147
136	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,
137	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
138	declared.	150	declared.
139		151
…		…
158		170
159	Some event loops issue spurious readyness notifications, so you should	171	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	173	handles.
162		174
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	179	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	180	warn "read: $input\n";
169	undef $w;	181	undef $w;
170	});	182	});
…		…
180		192
181	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	195	callbacks cannot use arguments passed to time watcher callbacks.
184		196
185	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
186	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
187	and Glib).	199	invoked regularly at that interval (in fractional seconds) after the first
		200	invocation.
188		201
189	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.
190		205
191	# fire an event after 7.7 seconds	206	Example: fire an event after 7.7 seconds.
		207
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	208	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	209	warn "timeout\n";
194	});	210	});
195		211
196	# to cancel the timer:	212	# to cancel the timer:
197	undef $w;	213	undef $w;
198		214
199	Example 2:
200
201	# 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.
202	my $w;
203		216
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	217	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		218	warn "timeout\n";
207	};	219	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		220
212	=head3 TIMING ISSUES	221	=head3 TIMING ISSUES
213		222
214	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
215	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
…		…
227	timers.	236	timers.
228		237
229	AnyEvent always prefers relative timers, if available, matching the	238	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	239	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	304	=head2 SIGNAL WATCHERS
233		305
234	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
235	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
236	be invoked whenever a signal occurs.	308	be invoked whenever a signal occurs.
237		309
238	Although the callback might get passed parameters, their value and	310	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	311	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	312	callbacks cannot use arguments passed to signal watcher callbacks.
241		313
242	Multiple signal occurances can be clumped together into one callback	314	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	315	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	317	but it is guaranteed not to interrupt any other callbacks.
246		318
247	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
248	between multiple watchers.	320	between multiple watchers.
249		321
250	This watcher might use C<%SIG>, so programs overwriting those signals	322	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
277	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
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	350	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		351
280	Example: fork a process and wait for it	352	Example: fork a process and wait for it
281		353
282	my $done = AnyEvent->condvar;	354	my $done = AnyEvent->condvar;
283		355
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	356	my $pid = fork or exit 5;
287		357
288	my $w = AnyEvent->child (	358	my $w = AnyEvent->child (
289	pid => $pid,	359	pid => $pid,
290	cb => sub {	360	cb => sub {
291	my ($pid, $status) = @_;	361	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	362	warn "pid $pid exited with status $status";
293	$done->send;	363	$done->send;
294	},	364	},
295	);	365	);
296		366
297	# do something else, then wait for process exit	367	# do something else, then wait for process exit
298	$done->wait;	368	$done->recv;
299		369
300	=head2 CONDITION VARIABLES	370	=head2 CONDITION VARIABLES
301		371
302	If you are familiar with some event loops you will know that all of them	372	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	373	require you to run some blocking "loop", "run" or similar function that
…		…
312	Condition variables can be created by calling the C<< AnyEvent->condvar	382	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	383	>> method, usually without arguments. The only argument pair allowed is
314	C<cb>, which specifies a callback to be called when the condition variable	384	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	385	becomes true.
316		386
317	After creation, the conditon variable is "false" until it becomes "true"	387	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<send> method.	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).
319		391
320	Condition variables are similar to callbacks, except that you can	392	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	393	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	394	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	395	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	396	used to represent a transaction, which finishes at some point and delivers
325	a result.	397	a result.
326		398
327	Condition variables are very useful to signal that something has finished,	399	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	400	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	401	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	402	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	403	called or can synchronously C<< ->recv >> for the results.
332		404
333	You can also use them to simulate traditional event loops - for example,	405	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	406	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	407	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->send >> 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 pieces 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	Condition variables are represented by hash refs in perl, and the keys	416	Condition variables are represented by hash refs in perl, and the keys
…		…
349		421
350	There are two "sides" to a condition variable - the "producer side" which	422	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> send >>, and the "consumer side", which waits	423	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the send to occur.	424	for the send to occur.
353		425
354	Example:	426	Example: wait for a timer.
355		427
356	# wait till the result is ready	428	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	429	my $result_ready = AnyEvent->condvar;
358		430
359	# do something such as adding a timer	431	# do something such as adding a timer
…		…
365	cb => sub { $result_ready->send },	437	cb => sub { $result_ready->send },
366	);	438	);
367		439
368	# this "blocks" (while handling events) till the callback	440	# this "blocks" (while handling events) till the callback
369	# calls send	441	# calls send
370	$result_ready->wait;	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;
371		450
372	=head3 METHODS FOR PRODUCERS	451	=head3 METHODS FOR PRODUCERS
373		452
374	These methods should only be used by the producing side, i.e. the	453	These methods should only be used by the producing side, i.e. the
375	code/module that eventually sends the signal. Note that it is also	454	code/module that eventually sends the signal. Note that it is also
…		…
378		457
379	=over 4	458	=over 4
380		459
381	=item $cv->send (...)	460	=item $cv->send (...)
382		461
383	Flag the condition as ready - a running C<< ->wait >> and all further	462	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	463	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the send will be remembered.	464	called. If nobody is waiting the send will be remembered.
386		465
387	If a callback has been set on the condition variable, it is called	466	If a callback has been set on the condition variable, it is called
388	immediately from within send.	467	immediately from within send.
389		468
390	Any arguments passed to the C<send> call will be returned by all	469	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	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).
392		480
393	=item $cv->croak ($error)	481	=item $cv->croak ($error)
394		482
395	Similar to send, but causes all call's wait C<< ->wait >> to invoke	483	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	484	C<Carp::croak> with the given error message/object/scalar.
397		485
398	This can be used to signal any errors to the condition variable	486	This can be used to signal any errors to the condition variable
399	user/consumer.	487	user/consumer.
400		488
401	=item $cv->begin ([group callback])	489	=item $cv->begin ([group callback])
402		490
403	=item $cv->end	491	=item $cv->end
		492
		493	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		494
405	These two methods can be used to combine many transactions/events into	495	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	496	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	497	to use a condition variable for the whole process.
408		498
…		…
443	doesn't execute once).	533	doesn't execute once).
444		534
445	This is the general pattern when you "fan out" into multiple subrequests:	535	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>	536	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	537	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>.	538	C<begin> and for each subrequest you finish, call C<end>.
449		539
450	=back	540	=back
451		541
452	=head3 METHODS FOR CONSUMERS	542	=head3 METHODS FOR CONSUMERS
453		543
454	These methods should only be used by the consuming side, i.e. the	544	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	545	code awaits the condition.
456		546
457	=over 4	547	=over 4
458		548
459	=item $cv->wait	549	=item $cv->recv
460		550
461	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	551	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462	>> methods have been called on c<$cv>, while servicing other watchers	552	>> methods have been called on c<$cv>, while servicing other watchers
463	normally.	553	normally.
464		554
…		…
475	(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
476	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
477	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
478	condition variables with some kind of request results and supporting	568	condition variables with some kind of request results and supporting
479	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,
480	while still suppporting blocking waits if the caller so desires).	570	while still supporting blocking waits if the caller so desires).
481		571
482	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
483	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
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	574	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.	575	can supply.
486		576
487	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in	577	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe	578	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489	versions and also integrates coroutines into AnyEvent, making blocking	579	versions and also integrates coroutines into AnyEvent, making blocking
490	C<< ->wait >> calls perfectly safe as long as they are done from another	580	C<< ->recv >> calls perfectly safe as long as they are done from another
491	coroutine (one that doesn't run the event loop).	581	coroutine (one that doesn't run the event loop).
492		582
493	You can ensure that C<< -wait >> never blocks by setting a callback and	583	You can ensure that C<< -recv >> never blocks by setting a callback and
494	only calling C<< ->wait >> from within that callback (or at a later	584	only calling C<< ->recv >> from within that callback (or at a later
495	time). This will work even when the event loop does not support blocking	585	time). This will work even when the event loop does not support blocking
496	waits otherwise.	586	waits otherwise.
497		587
498	=item $bool = $cv->ready	588	=item $bool = $cv->ready
499		589
…		…
504		594
505	This is a mutator function that returns the callback set and optionally	595	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	596	replaces it before doing so.
507		597
508	The callback will be called when the condition becomes "true", i.e. when	598	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<wait> inside the callback	599	C<send> or C<croak> are called, with the only argument being the condition
510	or at any later time is guaranteed not to block.	600	variable itself. Calling C<recv> inside the callback or at any later time
		601	is guaranteed not to block.
511		602
512	=back	603	=back
513		604
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	605	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		606
…		…
549	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	640	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
550	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
551	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
552	runtime.	643	runtime.
553		644
		645	=item $guard = AnyEvent::post_detect { BLOCK }
		646
		647	Arranges for the code block to be executed as soon as the event model is
		648	autodetected (or immediately if this has already happened).
		649
		650	If called in scalar or list context, then it creates and returns an object
		651	that automatically removes the callback again when it is destroyed. See
		652	L<Coro::BDB> for a case where this is useful.
		653
554	=item @AnyEvent::detect	654	=item @AnyEvent::post_detect
555		655
556	If there are any code references in this array (you can C<push> to it	656	If there are any code references in this array (you can C<push> to it
557	before or after loading AnyEvent), then they will called directly after	657	before or after loading AnyEvent), then they will called directly after
558	the event loop has been chosen.	658	the event loop has been chosen.
559		659
560	You should check C<$AnyEvent::MODEL> before adding to this array, though:	660	You should check C<$AnyEvent::MODEL> before adding to this array, though:
561	if it contains a true value then the event loop has already been detected,	661	if it contains a true value then the event loop has already been detected,
562	and the array will be ignored.	662	and the array will be ignored.
		663
		664	Best use C<AnyEvent::post_detect { BLOCK }> instead.
563		665
564	=back	666	=back
565		667
566	=head1 WHAT TO DO IN A MODULE	668	=head1 WHAT TO DO IN A MODULE
567		669
…		…
571	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
572	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
573	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
574	to load the event module first.	676	to load the event module first.
575		677
576	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
577	the C<< ->send >> method has been called on it already. This is	679	the C<< ->send >> method has been called on it already. This is
578	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
579	events is to stay interactive.	681	events is to stay interactive.
580		682
581	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
582	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
583	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 >>
584	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).
585		687
586	=head1 WHAT TO DO IN THE MAIN PROGRAM	688	=head1 WHAT TO DO IN THE MAIN PROGRAM
587		689
588	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
…		…
590		692
591	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
592	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
593	decide which implementation to chose if some module relies on it.	695	decide which implementation to chose if some module relies on it.
594		696
595	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
596	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
597	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
598	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
599	modules might create watchers when they are loaded, and AnyEvent will	701	modules might create watchers when they are loaded, and AnyEvent will
600	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
601	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.
602		704
603	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
604	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	706	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
605	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
606		725
607	=head1 OTHER MODULES	726	=head1 OTHER MODULES
608		727
609	The following is a non-exhaustive list of additional modules that use	728	The following is a non-exhaustive list of additional modules that use
610	AnyEvent and can therefore be mixed easily with other AnyEvent modules	729	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
616	=item L<AnyEvent::Util>	735	=item L<AnyEvent::Util>
617		736
618	Contains various utility functions that replace often-used but blocking	737	Contains various utility functions that replace often-used but blocking
619	functions such as C<inet_aton> by event-/callback-based versions.	738	functions such as C<inet_aton> by event-/callback-based versions.
620		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
621	=item L<AnyEvent::Handle>	746	=item L<AnyEvent::Handle>
622		747
623	Provide read and write buffers and manages watchers for reads and writes.	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.
624		751
625	=item L<AnyEvent::Socket>	752	=item L<AnyEvent::DNS>
626		753
627	Provides a means to do non-blocking connects, accepts etc.	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.
628		760
629	=item L<AnyEvent::HTTPD>	761	=item L<AnyEvent::HTTPD>
630		762
631	Provides a simple web application server framework.	763	Provides a simple web application server framework.
632		764
633	=item L<AnyEvent::DNS>
634
635	Provides asynchronous DNS resolver capabilities, beyond what
636	L<AnyEvent::Util> offers.
637
638	=item L<AnyEvent::FastPing>	765	=item L<AnyEvent::FastPing>
639		766
640	The fastest ping in the west.	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>).
641		792
642	=item L<Net::IRC3>	793	=item L<Net::IRC3>
643		794
644	AnyEvent based IRC client module family.	795	AnyEvent based IRC client module family.
645		796
…		…
662		813
663	=item L<IO::Lambda>	814	=item L<IO::Lambda>
664		815
665	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	816	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
666		817
667	=item L<IO::AIO>
668
669	Truly asynchronous I/O, should be in the toolbox of every event
670	programmer. Can be trivially made to use AnyEvent.
671
672	=item L<BDB>
673
674	Truly asynchronous Berkeley DB access. Can be trivially made to use
675	AnyEvent.
676
677	=back	818	=back
678		819
679	=cut	820	=cut
680		821
681	package AnyEvent;	822	package AnyEvent;
…		…
683	no warnings;	824	no warnings;
684	use strict;	825	use strict;
685		826
686	use Carp;	827	use Carp;
687		828
688	our $VERSION = '3.4';	829	our $VERSION = 4.2;
689	our $MODEL;	830	our $MODEL;
690		831
691	our $AUTOLOAD;	832	our $AUTOLOAD;
692	our @ISA;	833	our @ISA;
693		834
		835	our @REGISTRY;
		836
		837	our $WIN32;
		838
		839	BEGIN {
		840	my $win32 = ! ! ($^O =~ /mswin32/i);
		841	eval "sub WIN32(){ $win32 }";
		842	}
		843
694	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	844	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
695		845
696	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	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		853	}
697		854
698	my @models = (	855	my @models = (
699	[EV:: => AnyEvent::Impl::EV::],	856	[EV:: => AnyEvent::Impl::EV::],
700	[Event:: => AnyEvent::Impl::Event::],	857	[Event:: => AnyEvent::Impl::Event::],
701	[Tk:: => AnyEvent::Impl::Tk::],
702	[Wx:: => AnyEvent::Impl::POE::],
703	[Prima:: => AnyEvent::Impl::POE::],
704	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	858	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
705	# everything below here will not be autoprobed as the pureperl backend should work everywhere	859	# everything below here will not be autoprobed
706	[Glib:: => AnyEvent::Impl::Glib::],	860	# as the pureperl backend should work everywhere
		861	# and is usually faster
		862	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		863	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
707	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	864	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
708	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	865	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
709	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	866	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		867	[Wx:: => AnyEvent::Impl::POE::],
		868	[Prima:: => AnyEvent::Impl::POE::],
710	);	869	);
711		870
712	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	871	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
713		872
714	our @detect;	873	our @post_detect;
		874
		875	sub post_detect(&) {
		876	my ($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	}
715		894
716	sub detect() {	895	sub detect() {
717	unless ($MODEL) {	896	unless ($MODEL) {
718	no strict 'refs';	897	no strict 'refs';
		898	local $SIG{__DIE__};
719		899
720	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	900	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
721	my $model = "AnyEvent::Impl::$1";	901	my $model = "AnyEvent::Impl::$1";
722	if (eval "require $model") {	902	if (eval "require $model") {
723	$MODEL = $model;	903	$MODEL = $model;
…		…
760	}	940	}
761		941
762	unshift @ISA, $MODEL;	942	unshift @ISA, $MODEL;
763	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
764		944
765	(shift @detect)->() while @detect;	945	(shift @post_detect)->() while @post_detect;
766	}	946	}
767		947
768	$MODEL	948	$MODEL
769	}	949	}
770		950
…		…
780	$class->$func (@_);	960	$class->$func (@_);
781	}	961	}
782		962
783	package AnyEvent::Base;	963	package AnyEvent::Base;
784		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
785	# default implementation for ->condvar, ->wait, ->broadcast	972	# default implementation for ->condvar
786		973
787	sub condvar {	974	sub condvar {
788	bless \my $flag, "AnyEvent::Base::CondVar"	975	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
789	}
790
791	sub AnyEvent::Base::CondVar::broadcast {
792	${$_[0]}++;
793	}
794
795	sub AnyEvent::Base::CondVar::wait {
796	AnyEvent->one_event while !${$_[0]};
797	}	976	}
798		977
799	# default implementation for ->signal	978	# default implementation for ->signal
800		979
801	our %SIG_CB;	980	our %SIG_CB;
…		…
817	sub AnyEvent::Base::Signal::DESTROY {	996	sub AnyEvent::Base::Signal::DESTROY {
818	my ($signal, $cb) = @{$_[0]};	997	my ($signal, $cb) = @{$_[0]};
819		998
820	delete $SIG_CB{$signal}{$cb};	999	delete $SIG_CB{$signal}{$cb};
821		1000
822	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1001	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
823	}	1002	}
824		1003
825	# default implementation for ->child	1004	# default implementation for ->child
826		1005
827	our %PID_CB;	1006	our %PID_CB;
…		…
854	or Carp::croak "required option 'pid' is missing";	1033	or Carp::croak "required option 'pid' is missing";
855		1034
856	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1035	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
857		1036
858	unless ($WNOHANG) {	1037	unless ($WNOHANG) {
859	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1038	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
860	}	1039	}
861		1040
862	unless ($CHLD_W) {	1041	unless ($CHLD_W) {
863	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1042	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
864	# 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
…		…
874	delete $PID_CB{$pid}{$cb};	1053	delete $PID_CB{$pid}{$cb};
875	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1054	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
876		1055
877	undef $CHLD_W unless keys %PID_CB;	1056	undef $CHLD_W unless keys %PID_CB;
878	}	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;
879		1118
880	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1119	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
881		1120
882	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
883	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
…		…
940	model it chooses.	1179	model it chooses.
941		1180
942	=item C<PERL_ANYEVENT_MODEL>	1181	=item C<PERL_ANYEVENT_MODEL>
943		1182
944	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
945	autodetection and -probing kicks in. It must be a string consisting	1184	auto detection and -probing kicks in. It must be a string consisting
946	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1185	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
947	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,
948	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
949	autodetection and -probing.	1188	auto detection and -probing.
950		1189
951	This functionality might change in future versions.	1190	This functionality might change in future versions.
952		1191
953	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
954	could start your program like this:	1193	could start your program like this:
955		1194
956	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.
957		1232
958	=back	1233	=back
959		1234
960	=head1 EXAMPLE PROGRAM	1235	=head1 EXAMPLE PROGRAM
961		1236
…		…
972	poll => 'r',	1247	poll => 'r',
973	cb => sub {	1248	cb => sub {
974	warn "io event <$_[0]>\n"; # will always output <r>	1249	warn "io event <$_[0]>\n"; # will always output <r>
975	chomp (my $input = <STDIN>); # read a line	1250	chomp (my $input = <STDIN>); # read a line
976	warn "read: $input\n"; # output what has been read	1251	warn "read: $input\n"; # output what has been read
977	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1252	$cv->send if $input =~ /^q/i; # quit program if /^q/i
978	},	1253	},
979	);	1254	);
980		1255
981	my $time_watcher; # can only be used once	1256	my $time_watcher; # can only be used once
982		1257
…		…
987	});	1262	});
988	}	1263	}
989		1264
990	new_timer; # create first timer	1265	new_timer; # create first timer
991		1266
992	$cv->wait; # wait until user enters /^q/i	1267	$cv->recv; # wait until user enters /^q/i
993		1268
994	=head1 REAL-WORLD EXAMPLE	1269	=head1 REAL-WORLD EXAMPLE
995		1270
996	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
997	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:
…		…
1047	syswrite $txn->{fh}, $txn->{request}	1322	syswrite $txn->{fh}, $txn->{request}
1048	or die "connection or write error";	1323	or die "connection or write error";
1049	$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 });
1050		1325
1051	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
1052	result and signals any possible waiters that the request ahs finished:	1327	result and signals any possible waiters that the request has finished:
1053		1328
1054	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1329	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1055		1330
1056	if (end-of-file or data complete) {	1331	if (end-of-file or data complete) {
1057	$txn->{result} = $txn->{buf};	1332	$txn->{result} = $txn->{buf};
1058	$txn->{finished}->broadcast;	1333	$txn->{finished}->send;
1059	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1334	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1060	}	1335	}
1061		1336
1062	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
1063	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
1064	data:	1339	data:
1065		1340
1066	$txn->{finished}->wait;	1341	$txn->{finished}->recv;
1067	return $txn->{result};	1342	return $txn->{result};
1068		1343
1069	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)
1070	that occured during request processing. The C<result> method detects	1345	that occurred during request processing. The C<result> method detects
1071	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)
1072	and just throws the exception, which means connection errors and other	1347	and just throws the exception, which means connection errors and other
1073	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
1074	random callback.	1349	random callback.
1075		1350
…		…
1106		1381
1107	my $quit = AnyEvent->condvar;	1382	my $quit = AnyEvent->condvar;
1108		1383
1109	$fcp->txn_client_get ($url)->cb (sub {	1384	$fcp->txn_client_get ($url)->cb (sub {
1110	...	1385	...
1111	$quit->broadcast;	1386	$quit->send;
1112	});	1387	});
1113		1388
1114	$quit->wait;	1389	$quit->recv;
1115		1390
1116		1391
1117	=head1 BENCHMARKS	1392	=head1 BENCHMARKS
1118		1393
1119	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
…		…
1121	of various event loops I prepared some benchmarks.	1396	of various event loops I prepared some benchmarks.
1122		1397
1123	=head2 BENCHMARKING ANYEVENT OVERHEAD	1398	=head2 BENCHMARKING ANYEVENT OVERHEAD
1124		1399
1125	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
1126	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
1127	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,
1128	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.
1129		1404
1130	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
1131	distribution.	1406	distribution.
…		…
1148	all watchers, to avoid adding memory overhead. That means closure creation	1423	all watchers, to avoid adding memory overhead. That means closure creation
1149	and memory usage is not included in the figures.	1424	and memory usage is not included in the figures.
1150		1425
1151	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
1152	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
1153	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1428	invoked "watcher" times, it would C<< ->send >> a condvar once to
1154	signal the end of this phase.	1429	signal the end of this phase.
1155		1430
1156	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
1157	watcher.	1432	watcher.
1158		1433
…		…
1254		1529
1255	=back	1530	=back
1256		1531
1257	=head2 BENCHMARKING THE LARGE SERVER CASE	1532	=head2 BENCHMARKING THE LARGE SERVER CASE
1258		1533
1259	This benchmark atcually benchmarks the event loop itself. It works by	1534	This benchmark actually benchmarks the event loop itself. It works by
1260	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
1261	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
1262	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
1263	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".
1264		1539
1265	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
1266	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
1267	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
1268	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
1269	most timeouts work (and puts extra pressure on the event loops).	1544	most timeouts work (and puts extra pressure on the event loops).
1270		1545
1271	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
1272	(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
1273	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.
1274		1549
1275	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
1276	distribution.	1551	distribution.
…		…
1278	=head3 Explanation of the columns	1553	=head3 Explanation of the columns
1279		1554
1280	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
1281	each server has a read and write socket end).	1556	each server has a read and write socket end).
1282		1557
1283	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
1284	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.
1285		1560
1286	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
1287	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
1288	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
…		…
1361	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
1362	them).	1637	them).
1363		1638
1364	EV is again fastest.	1639	EV is again fastest.
1365		1640
1366	Perl again comes second. It is noticably faster than the C-based event	1641	Perl again comes second. It is noticeably faster than the C-based event
1367	loops Event and Glib, although the difference is too small to really	1642	loops Event and Glib, although the difference is too small to really
1368	matter.	1643	matter.
1369		1644
1370	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
1371	others.	1646	others.
…		…
1400	specified in the variable.	1675	specified in the variable.
1401		1676
1402	You can make AnyEvent completely ignore this variable by deleting it	1677	You can make AnyEvent completely ignore this variable by deleting it
1403	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:
1404		1679
1405	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1680	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1406		1681
1407	use AnyEvent;	1682	use AnyEvent;
1408		1683
1409	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1684	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1410	be used to probe what backend is used and gain other information (which is	1685	be used to probe what backend is used and gain other information (which is
1411	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1686	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1412		1687
1413		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).
		1696
		1697
1414	=head1 SEE ALSO	1698	=head1 SEE ALSO
		1699
		1700	Utility functions: L<AnyEvent::Util>.
1415		1701
1416	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	1702	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1417	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	1703	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1418		1704
1419	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	1705	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1420	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	1706	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1421	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	1707	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1422	L<AnyEvent::Impl::POE>.	1708	L<AnyEvent::Impl::POE>.
1423		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
1424	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	1715	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1425		1716
1426	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1717	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1427		1718
1428		1719
1429	=head1 AUTHOR	1720	=head1 AUTHOR
1430		1721
1431	Marc Lehmann <schmorp@schmorp.de>	1722	Marc Lehmann <schmorp@schmorp.de>
1432	http://home.schmorp.de/	1723	http://home.schmorp.de/
1433		1724
1434	=cut	1725	=cut
1435		1726
1436	1	1727	1
1437		1728

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.108 by root, Sat May 10 00:22:02 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 1.108 by root, Sat May 10 00:22:02 2008 UTC vs.
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC