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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC vs.
Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC

…		…
1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub { ... });
12	...
13	});
14		12
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
16	...	23	...
17	});	24	});
18		25
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	27	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	28	$w->recv; # enters "main loop" till $condvar gets ->send
		29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	48	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	49	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	63	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	64	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
102	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
118	is in control).	140	is in control).
119		141
		142	Note that B<callbacks must not permanently change global variables>
		143	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		144	callbacks must not C<die> >>. The former is good programming practise in
		145	Perl and the latter stems from the fact that exception handling differs
		146	widely between event loops.
		147
120	To disable the watcher you have to destroy it (e.g. by setting the	148	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	149	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	150	to it).
123		151
124	All watchers are created by calling a method on the C<AnyEvent> class.	152	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	155	example), or need to refer to their watcher object in other ways.
128		156
129	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
130		158
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
133	undef $w;	161	undef $w;
134	});	162	});
135		163
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	164	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	165	my variables are only visible after the statement in which they are
138	declared.	166	declared.
139		167
140	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
141		169
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
144		172
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	173	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		174	for events (AnyEvent might or might not keep a reference to this file
		175	handle). Note that only file handles pointing to things for which
		176	non-blocking operation makes sense are allowed. This includes sockets,
		177	most character devices, pipes, fifos and so on, but not for example files
		178	or block devices.
		179
146	for events. C<poll> must be a string that is either C<r> or C<w>,	180	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
148	respectively. C<cb> is the callback to invoke each time the file handle	183	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		184
151	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
154		188
…		…
158		192
159	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	194	always use non-blocking calls when reading/writing from/to your file
161	handles.	195	handles.
162		196
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	197	Example: wait for readability of STDIN, then read a line and disable the
		198	watcher.
		199
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	202	warn "read: $input\n";
169	undef $w;	203	undef $w;
170	});	204	});
…		…
180		214
181	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
184		218
185	The timer callback will be invoked at most once: if you want a repeating	219	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	220	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	221	callback will be invoked regularly at that interval (in fractional
		222	seconds) after the first invocation. If C<interval> is specified with a
		223	false value, then it is treated as if it were missing.
188		224
189	Example:	225	The callback will be rescheduled before invoking the callback, but no
		226	attempt is done to avoid timer drift in most backends, so the interval is
		227	only approximate.
190		228
191	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	232	warn "timeout\n";
194	});	233	});
195		234
196	# to cancel the timer:	235	# to cancel the timer:
197	undef $w;	236	undef $w;
198		237
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	238	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		239
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
207	};	242	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		243
212	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
213		245
214	There are two ways to handle timers: based on real time (relative, "fire	246	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	247	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	259	timers.
228		260
229	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	262	AnyEvent API.
231		263
		264	AnyEvent has two additional methods that return the "current time":
		265
		266	=over 4
		267
		268	=item AnyEvent->time
		269
		270	This returns the "current wallclock time" as a fractional number of
		271	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		272	return, and the result is guaranteed to be compatible with those).
		273
		274	It progresses independently of any event loop processing, i.e. each call
		275	will check the system clock, which usually gets updated frequently.
		276
		277	=item AnyEvent->now
		278
		279	This also returns the "current wallclock time", but unlike C<time>, above,
		280	this value might change only once per event loop iteration, depending on
		281	the event loop (most return the same time as C<time>, above). This is the
		282	time that AnyEvent's timers get scheduled against.
		283
		284	I<In almost all cases (in all cases if you don't care), this is the
		285	function to call when you want to know the current time.>
		286
		287	This function is also often faster then C<< AnyEvent->time >>, and
		288	thus the preferred method if you want some timestamp (for example,
		289	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		290
		291	The rest of this section is only of relevance if you try to be very exact
		292	with your timing, you can skip it without bad conscience.
		293
		294	For a practical example of when these times differ, consider L<Event::Lib>
		295	and L<EV> and the following set-up:
		296
		297	The event loop is running and has just invoked one of your callback at
		298	time=500 (assume no other callbacks delay processing). In your callback,
		299	you wait a second by executing C<sleep 1> (blocking the process for a
		300	second) and then (at time=501) you create a relative timer that fires
		301	after three seconds.
		302
		303	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		304	both return C<501>, because that is the current time, and the timer will
		305	be scheduled to fire at time=504 (C<501> + C<3>).
		306
		307	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		308	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		309	last event processing phase started. With L<EV>, your timer gets scheduled
		310	to run at time=503 (C<500> + C<3>).
		311
		312	In one sense, L<Event::Lib> is more exact, as it uses the current time
		313	regardless of any delays introduced by event processing. However, most
		314	callbacks do not expect large delays in processing, so this causes a
		315	higher drift (and a lot more system calls to get the current time).
		316
		317	In another sense, L<EV> is more exact, as your timer will be scheduled at
		318	the same time, regardless of how long event processing actually took.
		319
		320	In either case, if you care (and in most cases, you don't), then you
		321	can get whatever behaviour you want with any event loop, by taking the
		322	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		323	account.
		324
		325	=back
		326
232	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
233		328
234	You can watch for signals using a signal watcher, C<signal> is the signal	329	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	330	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
237		332
238	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
241		336
…		…
257	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
258		353
259	You can also watch on a child process exit and catch its exit status.	354	You can also watch on a child process exit and catch its exit status.
260		355
261	The child process is specified by the C<pid> argument (if set to C<0>, it	356	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	357	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	358	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	359	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	360
266	you I<can> rely on child watcher callback arguments.	361	The callback will be called with the pid and exit status (as returned by
		362	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		363	callback arguments.
		364
		365	This watcher type works by installing a signal handler for C<SIGCHLD>,
		366	and since it cannot be shared, nothing else should use SIGCHLD or reap
		367	random child processes (waiting for specific child processes, e.g. inside
		368	C<system>, is just fine).
267		369
268	There is a slight catch to child watchers, however: you usually start them	370	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	371	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
271		373
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	379	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		381
280	Example: fork a process and wait for it	382	Example: fork a process and wait for it
281		383
282	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
283		385
284	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
285		387
286	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
287	pid => $pid,	389	pid => $pid,
288	cb => sub {	390	cb => sub {
289	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
291	$done->send;	393	$done->send;
292	},	394	},
293	);	395	);
294		396
295	# do something else, then wait for process exit	397	# do something else, then wait for process exit
296	$done->recv;	398	$done->recv;
297		399
298	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
299		401
300	If you are familiar with some event loops you will know that all of them	402	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	403	require you to run some blocking "loop", "run" or similar function that
…		…
307	The instrument to do that is called a "condition variable", so called	409	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	410	because they represent a condition that must become true.
309		411
310	Condition variables can be created by calling the C<< AnyEvent->condvar	412	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	413	>> method, usually without arguments. The only argument pair allowed is
		414
312	C<cb>, which specifies a callback to be called when the condition variable	415	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
314		418
315	After creation, the condition variable is "false" until it becomes "true"	419	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	420	by calling the C<send> method (or calling the condition variable as if it
317	were a callback).	421	were a callback, read about the caveats in the description for the C<<
		422	->send >> method).
318		423
319	Condition variables are similar to callbacks, except that you can	424	Condition variables are similar to callbacks, except that you can
320	optionally wait for them. They can also be called merge points - points	425	optionally wait for them. They can also be called merge points - points
321	in time where multiple outstanding events have been processed. And yet	426	in time where multiple outstanding events have been processed. And yet
322	another way to call them is transactions - each condition variable can be	427	another way to call them is transactions - each condition variable can be
…		…
373		478
374	my $done = AnyEvent->condvar;	479	my $done = AnyEvent->condvar;
375	my $delay = AnyEvent->timer (after => 5, cb => $done);	480	my $delay = AnyEvent->timer (after => 5, cb => $done);
376	$done->recv;	481	$done->recv;
377		482
		483	Example: Imagine an API that returns a condvar and doesn't support
		484	callbacks. This is how you make a synchronous call, for example from
		485	the main program:
		486
		487	use AnyEvent::CouchDB;
		488
		489	...
		490
		491	my @info = $couchdb->info->recv;
		492
		493	And this is how you would just ste a callback to be called whenever the
		494	results are available:
		495
		496	$couchdb->info->cb (sub {
		497	my @info = $_[0]->recv;
		498	});
		499
378	=head3 METHODS FOR PRODUCERS	500	=head3 METHODS FOR PRODUCERS
379		501
380	These methods should only be used by the producing side, i.e. the	502	These methods should only be used by the producing side, i.e. the
381	code/module that eventually sends the signal. Note that it is also	503	code/module that eventually sends the signal. Note that it is also
382	the producer side which creates the condvar in most cases, but it isn't	504	the producer side which creates the condvar in most cases, but it isn't
…		…
394	immediately from within send.	516	immediately from within send.
395		517
396	Any arguments passed to the C<send> call will be returned by all	518	Any arguments passed to the C<send> call will be returned by all
397	future C<< ->recv >> calls.	519	future C<< ->recv >> calls.
398		520
399	Condition variables are overloaded so one can call them directly (as a	521	Condition variables are overloaded so one can call them directly
400	code reference). Calling them directly is the same as calling C<send>.	522	(as a code reference). Calling them directly is the same as calling
		523	C<send>. Note, however, that many C-based event loops do not handle
		524	overloading, so as tempting as it may be, passing a condition variable
		525	instead of a callback does not work. Both the pure perl and EV loops
		526	support overloading, however, as well as all functions that use perl to
		527	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		528	example).
401		529
402	=item $cv->croak ($error)	530	=item $cv->croak ($error)
403		531
404	Similar to send, but causes all call's to C<< ->recv >> to invoke	532	Similar to send, but causes all call's to C<< ->recv >> to invoke
405	C<Carp::croak> with the given error message/object/scalar.	533	C<Carp::croak> with the given error message/object/scalar.
…		…
509	=item $bool = $cv->ready	637	=item $bool = $cv->ready
510		638
511	Returns true when the condition is "true", i.e. whether C<send> or	639	Returns true when the condition is "true", i.e. whether C<send> or
512	C<croak> have been called.	640	C<croak> have been called.
513		641
514	=item $cb = $cv->cb ([new callback])	642	=item $cb = $cv->cb ($cb->($cv))
515		643
516	This is a mutator function that returns the callback set and optionally	644	This is a mutator function that returns the callback set and optionally
517	replaces it before doing so.	645	replaces it before doing so.
518		646
519	The callback will be called when the condition becomes "true", i.e. when	647	The callback will be called when the condition becomes "true", i.e. when
520	C<send> or C<croak> are called. Calling C<recv> inside the callback	648	C<send> or C<croak> are called, with the only argument being the condition
521	or at any later time is guaranteed not to block.	649	variable itself. Calling C<recv> inside the callback or at any later time
		650	is guaranteed not to block.
522		651
523	=back	652	=back
524		653
525	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
526		655
…		…
612		741
613	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	742	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
614	do anything special (it does not need to be event-based) and let AnyEvent	743	do anything special (it does not need to be event-based) and let AnyEvent
615	decide which implementation to chose if some module relies on it.	744	decide which implementation to chose if some module relies on it.
616		745
617	If the main program relies on a specific event model. For example, in	746	If the main program relies on a specific event model - for example, in
618	Gtk2 programs you have to rely on the Glib module. You should load the	747	Gtk2 programs you have to rely on the Glib module - you should load the
619	event module before loading AnyEvent or any module that uses it: generally	748	event module before loading AnyEvent or any module that uses it: generally
620	speaking, you should load it as early as possible. The reason is that	749	speaking, you should load it as early as possible. The reason is that
621	modules might create watchers when they are loaded, and AnyEvent will	750	modules might create watchers when they are loaded, and AnyEvent will
622	decide on the event model to use as soon as it creates watchers, and it	751	decide on the event model to use as soon as it creates watchers, and it
623	might chose the wrong one unless you load the correct one yourself.	752	might chose the wrong one unless you load the correct one yourself.
624		753
625	You can chose to use a rather inefficient pure-perl implementation by	754	You can chose to use a pure-perl implementation by loading the
626	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
627	behaviour everywhere, but letting AnyEvent chose is generally better.	756	everywhere, but letting AnyEvent chose the model is generally better.
		757
		758	=head2 MAINLOOP EMULATION
		759
		760	Sometimes (often for short test scripts, or even standalone programs who
		761	only want to use AnyEvent), you do not want to run a specific event loop.
		762
		763	In that case, you can use a condition variable like this:
		764
		765	AnyEvent->condvar->recv;
		766
		767	This has the effect of entering the event loop and looping forever.
		768
		769	Note that usually your program has some exit condition, in which case
		770	it is better to use the "traditional" approach of storing a condition
		771	variable somewhere, waiting for it, and sending it when the program should
		772	exit cleanly.
		773
628		774
629	=head1 OTHER MODULES	775	=head1 OTHER MODULES
630		776
631	The following is a non-exhaustive list of additional modules that use	777	The following is a non-exhaustive list of additional modules that use
632	AnyEvent and can therefore be mixed easily with other AnyEvent modules	778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
638	=item L<AnyEvent::Util>	784	=item L<AnyEvent::Util>
639		785
640	Contains various utility functions that replace often-used but blocking	786	Contains various utility functions that replace often-used but blocking
641	functions such as C<inet_aton> by event-/callback-based versions.	787	functions such as C<inet_aton> by event-/callback-based versions.
642		788
643	=item L<AnyEvent::Handle>
644
645	Provide read and write buffers and manages watchers for reads and writes.
646
647	=item L<AnyEvent::Socket>	789	=item L<AnyEvent::Socket>
648		790
649	Provides various utility functions for (internet protocol) sockets,	791	Provides various utility functions for (internet protocol) sockets,
650	addresses and name resolution. Also functions to create non-blocking tcp	792	addresses and name resolution. Also functions to create non-blocking tcp
651	connections or tcp servers, with IPv6 and SRV record support and more.	793	connections or tcp servers, with IPv6 and SRV record support and more.
652		794
		795	=item L<AnyEvent::Handle>
		796
		797	Provide read and write buffers, manages watchers for reads and writes,
		798	supports raw and formatted I/O, I/O queued and fully transparent and
		799	non-blocking SSL/TLS.
		800
		801	=item L<AnyEvent::DNS>
		802
		803	Provides rich asynchronous DNS resolver capabilities.
		804
		805	=item L<AnyEvent::HTTP>
		806
		807	A simple-to-use HTTP library that is capable of making a lot of concurrent
		808	HTTP requests.
		809
653	=item L<AnyEvent::HTTPD>	810	=item L<AnyEvent::HTTPD>
654		811
655	Provides a simple web application server framework.	812	Provides a simple web application server framework.
656		813
657	=item L<AnyEvent::DNS>
658
659	Provides rich asynchronous DNS resolver capabilities.
660
661	=item L<AnyEvent::FastPing>	814	=item L<AnyEvent::FastPing>
662		815
663	The fastest ping in the west.	816	The fastest ping in the west.
664		817
		818	=item L<AnyEvent::DBI>
		819
		820	Executes L<DBI> requests asynchronously in a proxy process.
		821
		822	=item L<AnyEvent::AIO>
		823
		824	Truly asynchronous I/O, should be in the toolbox of every event
		825	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		826	together.
		827
		828	=item L<AnyEvent::BDB>
		829
		830	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		831	L<BDB> and AnyEvent together.
		832
		833	=item L<AnyEvent::GPSD>
		834
		835	A non-blocking interface to gpsd, a daemon delivering GPS information.
		836
		837	=item L<AnyEvent::IGS>
		838
		839	A non-blocking interface to the Internet Go Server protocol (used by
		840	L<App::IGS>).
		841
665	=item L<Net::IRC3>	842	=item L<AnyEvent::IRC>
666		843
667	AnyEvent based IRC client module family.	844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
668		845
669	=item L<Net::XMPP2>	846	=item L<Net::XMPP2>
670		847
671	AnyEvent based XMPP (Jabber protocol) module family.	848	AnyEvent based XMPP (Jabber protocol) module family.
672		849
…		…
681		858
682	=item L<Coro>	859	=item L<Coro>
683		860
684	Has special support for AnyEvent via L<Coro::AnyEvent>.	861	Has special support for AnyEvent via L<Coro::AnyEvent>.
685		862
686	=item L<AnyEvent::AIO>, L<IO::AIO>
687
688	Truly asynchronous I/O, should be in the toolbox of every event
689	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
690	together.
691
692	=item L<AnyEvent::BDB>, L<BDB>
693
694	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
695	IO::AIO and AnyEvent together.
696
697	=item L<IO::Lambda>	863	=item L<IO::Lambda>
698		864
699	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
700		866
701	=back	867	=back
…		…
703	=cut	869	=cut
704		870
705	package AnyEvent;	871	package AnyEvent;
706		872
707	no warnings;	873	no warnings;
708	use strict;	874	use strict qw(vars subs);
709		875
710	use Carp;	876	use Carp;
711		877
712	our $VERSION = '4.0';	878	our $VERSION = 4.35;
713	our $MODEL;	879	our $MODEL;
714		880
715	our $AUTOLOAD;	881	our $AUTOLOAD;
716	our @ISA;	882	our @ISA;
717		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
718	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
719		894
720	our @REGISTRY;	895	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
721
722	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
723		896
724	{	897	{
725	my $idx;	898	my $idx;
726	$PROTOCOL{$_} = ++$idx	899	$PROTOCOL{$_} = ++$idx
		900	for reverse split /\s,\s/,
727	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";	901	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
728	}	902	}
729		903
730	my @models = (	904	my @models = (
731	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
732	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
733	[Tk:: => AnyEvent::Impl::Tk::],
734	[Wx:: => AnyEvent::Impl::POE::],
735	[Prima:: => AnyEvent::Impl::POE::],
736	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
737	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
738	[Glib:: => AnyEvent::Impl::Glib::],	909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
739	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
740	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
741	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
742	);	918	);
743		919
744	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
745		921
746	our @post_detect;	922	our @post_detect;
747		923
748	sub post_detect(&) {	924	sub post_detect(&) {
749	my ($cb) = @_;	925	my ($cb) = @_;
…		…
766	}	942	}
767		943
768	sub detect() {	944	sub detect() {
769	unless ($MODEL) {	945	unless ($MODEL) {
770	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
771		948
772	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
773	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
774	if (eval "require $model") {	951	if (eval "require $model") {
775	$MODEL = $model;	952	$MODEL = $model;
…		…
809	$MODEL	986	$MODEL
810	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
811	}	988	}
812	}	989	}
813		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
814	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
815	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
816		996
817	(shift @post_detect)->() while @post_detect;	997	(shift @post_detect)->() while @post_detect;
818	}	998	}
819		999
820	$MODEL	1000	$MODEL
…		…
830		1010
831	my $class = shift;	1011	my $class = shift;
832	$class->$func (@_);	1012	$class->$func (@_);
833	}	1013	}
834		1014
		1015	# utility function to dup a filehandle. this is used by many backends
		1016	# to support binding more than one watcher per filehandle (they usually
		1017	# allow only one watcher per fd, so we dup it to get a different one).
		1018	sub _dupfh($$$$) {
		1019	my ($poll, $fh, $r, $w) = @_;
		1020
		1021	# cygwin requires the fh mode to be matching, unix doesn't
		1022	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1023	: $poll eq "w" ? ($w, ">")
		1024	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1025
		1026	open my $fh2, "$mode&" . fileno $fh
		1027	or die "cannot dup() filehandle: $!";
		1028
		1029	# we assume CLOEXEC is already set by perl in all important cases
		1030
		1031	($fh2, $rw)
		1032	}
		1033
835	package AnyEvent::Base;	1034	package AnyEvent::Base;
		1035
		1036	# default implementation for now and time
		1037
		1038	BEGIN {
		1039	if (eval "use Time::HiRes (); time (); 1") {
		1040	*_time = \&Time::HiRes::time;
		1041	# if (eval "use POSIX (); (POSIX::times())...
		1042	} else {
		1043	*_time = sub { time }; # epic fail
		1044	}
		1045	}
		1046
		1047	sub time { _time }
		1048	sub now { _time }
836		1049
837	# default implementation for ->condvar	1050	# default implementation for ->condvar
838		1051
839	sub condvar {	1052	sub condvar {
840	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
841	}	1054	}
842		1055
843	# default implementation for ->signal	1056	# default implementation for ->signal
844		1057
845	our %SIG_CB;	1058	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1059
		1060	sub _signal_exec {
		1061	sysread $SIGPIPE_R, my $dummy, 4;
		1062
		1063	while (%SIG_EV) {
		1064	for (keys %SIG_EV) {
		1065	delete $SIG_EV{$_};
		1066	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1067	}
		1068	}
		1069	}
846		1070
847	sub signal {	1071	sub signal {
848	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
849		1073
		1074	unless ($SIGPIPE_R) {
		1075	require Fcntl;
		1076
		1077	if (AnyEvent::WIN32) {
		1078	require AnyEvent::Util;
		1079
		1080	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1081	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1082	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1083	} else {
		1084	pipe $SIGPIPE_R, $SIGPIPE_W;
		1085	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1086	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1087	}
		1088
		1089	$SIGPIPE_R
		1090	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1091
		1092	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1093	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094
		1095	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1096	}
		1097
850	my $signal = uc $arg{signal}	1098	my $signal = uc $arg{signal}
851	or Carp::croak "required option 'signal' is missing";	1099	or Carp::croak "required option 'signal' is missing";
852		1100
853	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1101	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
854	$SIG{$signal} \|\|= sub {	1102	$SIG{$signal} \|\|= sub {
855	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1103	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1104	undef $SIG_EV{$signal};
856	};	1105	};
857		1106
858	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1107	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
859	}	1108	}
860		1109
861	sub AnyEvent::Base::Signal::DESTROY {	1110	sub AnyEvent::Base::Signal::DESTROY {
862	my ($signal, $cb) = @{$_[0]};	1111	my ($signal, $cb) = @{$_[0]};
863		1112
864	delete $SIG_CB{$signal}{$cb};	1113	delete $SIG_CB{$signal}{$cb};
865		1114
866	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1115	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
867	}	1116	}
868		1117
869	# default implementation for ->child	1118	# default implementation for ->child
870		1119
871	our %PID_CB;	1120	our %PID_CB;
…		…
898	or Carp::croak "required option 'pid' is missing";	1147	or Carp::croak "required option 'pid' is missing";
899		1148
900	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1149	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
901		1150
902	unless ($WNOHANG) {	1151	unless ($WNOHANG) {
903	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1152	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
904	}	1153	}
905		1154
906	unless ($CHLD_W) {	1155	unless ($CHLD_W) {
907	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1156	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
908	# child could be a zombie already, so make at least one round	1157	# child could be a zombie already, so make at least one round
…		…
978	}	1227	}
979		1228
980	# undocumented/compatibility with pre-3.4	1229	# undocumented/compatibility with pre-3.4
981	*broadcast = \&send;	1230	*broadcast = \&send;
982	*wait = \&_wait;	1231	*wait = \&_wait;
		1232
		1233	=head1 ERROR AND EXCEPTION HANDLING
		1234
		1235	In general, AnyEvent does not do any error handling - it relies on the
		1236	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1237	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1238	checking of all AnyEvent methods, however, which is highly useful during
		1239	development.
		1240
		1241	As for exception handling (i.e. runtime errors and exceptions thrown while
		1242	executing a callback), this is not only highly event-loop specific, but
		1243	also not in any way wrapped by this module, as this is the job of the main
		1244	program.
		1245
		1246	The pure perl event loop simply re-throws the exception (usually
		1247	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1248	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1249	so on.
		1250
		1251	=head1 ENVIRONMENT VARIABLES
		1252
		1253	The following environment variables are used by this module or its
		1254	submodules:
		1255
		1256	=over 4
		1257
		1258	=item C<PERL_ANYEVENT_VERBOSE>
		1259
		1260	By default, AnyEvent will be completely silent except in fatal
		1261	conditions. You can set this environment variable to make AnyEvent more
		1262	talkative.
		1263
		1264	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1265	conditions, such as not being able to load the event model specified by
		1266	C<PERL_ANYEVENT_MODEL>.
		1267
		1268	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1269	model it chooses.
		1270
		1271	=item C<PERL_ANYEVENT_STRICT>
		1272
		1273	AnyEvent does not do much argument checking by default, as thorough
		1274	argument checking is very costly. Setting this variable to a true value
		1275	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1276	check the arguments passed to most method calls. If it finds any problems
		1277	it will croak.
		1278
		1279	In other words, enables "strict" mode.
		1280
		1281	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1282	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1283	developing programs can be very useful, however.
		1284
		1285	=item C<PERL_ANYEVENT_MODEL>
		1286
		1287	This can be used to specify the event model to be used by AnyEvent, before
		1288	auto detection and -probing kicks in. It must be a string consisting
		1289	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1290	and the resulting module name is loaded and if the load was successful,
		1291	used as event model. If it fails to load AnyEvent will proceed with
		1292	auto detection and -probing.
		1293
		1294	This functionality might change in future versions.
		1295
		1296	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1297	could start your program like this:
		1298
		1299	PERL_ANYEVENT_MODEL=Perl perl ...
		1300
		1301	=item C<PERL_ANYEVENT_PROTOCOLS>
		1302
		1303	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1304	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1305	of auto probing).
		1306
		1307	Must be set to a comma-separated list of protocols or address families,
		1308	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1309	used, and preference will be given to protocols mentioned earlier in the
		1310	list.
		1311
		1312	This variable can effectively be used for denial-of-service attacks
		1313	against local programs (e.g. when setuid), although the impact is likely
		1314	small, as the program has to handle conenction and other failures anyways.
		1315
		1316	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1317	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1318	- only support IPv4, never try to resolve or contact IPv6
		1319	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1320	IPv6, but prefer IPv6 over IPv4.
		1321
		1322	=item C<PERL_ANYEVENT_EDNS0>
		1323
		1324	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1325	for DNS. This extension is generally useful to reduce DNS traffic, but
		1326	some (broken) firewalls drop such DNS packets, which is why it is off by
		1327	default.
		1328
		1329	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1330	EDNS0 in its DNS requests.
		1331
		1332	=item C<PERL_ANYEVENT_MAX_FORKS>
		1333
		1334	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1335	will create in parallel.
		1336
		1337	=back
983		1338
984	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1339	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
985		1340
986	This is an advanced topic that you do not normally need to use AnyEvent in	1341	This is an advanced topic that you do not normally need to use AnyEvent in
987	a module. This section is only of use to event loop authors who want to	1342	a module. This section is only of use to event loop authors who want to
…		…
1021		1376
1022	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1377	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1023	condition variables: code blocking while waiting for a condition will	1378	condition variables: code blocking while waiting for a condition will
1024	C<die>. This still works with most modules/usages, and blocking calls must	1379	C<die>. This still works with most modules/usages, and blocking calls must
1025	not be done in an interactive application, so it makes sense.	1380	not be done in an interactive application, so it makes sense.
1026
1027	=head1 ENVIRONMENT VARIABLES
1028
1029	The following environment variables are used by this module:
1030
1031	=over 4
1032
1033	=item C<PERL_ANYEVENT_VERBOSE>
1034
1035	By default, AnyEvent will be completely silent except in fatal
1036	conditions. You can set this environment variable to make AnyEvent more
1037	talkative.
1038
1039	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1040	conditions, such as not being able to load the event model specified by
1041	C<PERL_ANYEVENT_MODEL>.
1042
1043	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1044	model it chooses.
1045
1046	=item C<PERL_ANYEVENT_MODEL>
1047
1048	This can be used to specify the event model to be used by AnyEvent, before
1049	auto detection and -probing kicks in. It must be a string consisting
1050	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1051	and the resulting module name is loaded and if the load was successful,
1052	used as event model. If it fails to load AnyEvent will proceed with
1053	auto detection and -probing.
1054
1055	This functionality might change in future versions.
1056
1057	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1058	could start your program like this:
1059
1060	PERL_ANYEVENT_MODEL=Perl perl ...
1061
1062	=item C<PERL_ANYEVENT_PROTOCOLS>
1063
1064	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1065	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1066	of auto probing).
1067
1068	Must be set to a comma-separated list of protocols or address families,
1069	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1070	used, and preference will be given to protocols mentioned earlier in the
1071	list.
1072
1073	This variable can effectively be used for denial-of-service attacks
1074	against local programs (e.g. when setuid), although the impact is likely
1075	small, as the program has to handle connection errors already-
1076
1077	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1078	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1079	- only support IPv4, never try to resolve or contact IPv6
1080	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1081	IPv6, but prefer IPv6 over IPv4.
1082
1083	=item C<PERL_ANYEVENT_EDNS0>
1084
1085	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1086	for DNS. This extension is generally useful to reduce DNS traffic, but
1087	some (broken) firewalls drop such DNS packets, which is why it is off by
1088	default.
1089
1090	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1091	EDNS0 in its DNS requests.
1092
1093	=back
1094		1381
1095	=head1 EXAMPLE PROGRAM	1382	=head1 EXAMPLE PROGRAM
1096		1383
1097	The following program uses an I/O watcher to read data from STDIN, a timer	1384	The following program uses an I/O watcher to read data from STDIN, a timer
1098	to display a message once per second, and a condition variable to quit the	1385	to display a message once per second, and a condition variable to quit the
…		…
1292	watcher.	1579	watcher.
1293		1580
1294	=head3 Results	1581	=head3 Results
1295		1582
1296	name watchers bytes create invoke destroy comment	1583	name watchers bytes create invoke destroy comment
1297	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1584	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1298	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1585	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1299	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1586	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1300	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1587	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1301	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1588	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1302	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1589	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1303	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1590	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1304	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1591	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1305	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1592	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1306	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1593	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1307		1594
1308	=head3 Discussion	1595	=head3 Discussion
1309		1596
1310	The benchmark does I<not> measure scalability of the event loop very	1597	The benchmark does I<not> measure scalability of the event loop very
1311	well. For example, a select-based event loop (such as the pure perl one)	1598	well. For example, a select-based event loop (such as the pure perl one)
…		…
1513	watchers, as the management overhead dominates.	1800	watchers, as the management overhead dominates.
1514		1801
1515	=back	1802	=back
1516		1803
1517		1804
		1805	=head1 SIGNALS
		1806
		1807	AnyEvent currently installs handlers for these signals:
		1808
		1809	=over 4
		1810
		1811	=item SIGCHLD
		1812
		1813	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1814	emulation for event loops that do not support them natively. Also, some
		1815	event loops install a similar handler.
		1816
		1817	=item SIGPIPE
		1818
		1819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1820	when AnyEvent gets loaded.
		1821
		1822	The rationale for this is that AnyEvent users usually do not really depend
		1823	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1824	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1825	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1826	some random socket.
		1827
		1828	The rationale for installing a no-op handler as opposed to ignoring it is
		1829	that this way, the handler will be restored to defaults on exec.
		1830
		1831	Feel free to install your own handler, or reset it to defaults.
		1832
		1833	=back
		1834
		1835	=cut
		1836
		1837	$SIG{PIPE} = sub { }
		1838	unless defined $SIG{PIPE};
		1839
		1840
1518	=head1 FORK	1841	=head1 FORK
1519		1842
1520	Most event libraries are not fork-safe. The ones who are usually are	1843	Most event libraries are not fork-safe. The ones who are usually are
1521	because they rely on inefficient but fork-safe C<select> or C<poll>	1844	because they rely on inefficient but fork-safe C<select> or C<poll>
1522	calls. Only L<EV> is fully fork-aware.	1845	calls. Only L<EV> is fully fork-aware.
…		…
1535	specified in the variable.	1858	specified in the variable.
1536		1859
1537	You can make AnyEvent completely ignore this variable by deleting it	1860	You can make AnyEvent completely ignore this variable by deleting it
1538	before the first watcher gets created, e.g. with a C<BEGIN> block:	1861	before the first watcher gets created, e.g. with a C<BEGIN> block:
1539		1862
1540	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1863	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1541		1864
1542	use AnyEvent;	1865	use AnyEvent;
1543		1866
1544	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1867	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1545	be used to probe what backend is used and gain other information (which is	1868	be used to probe what backend is used and gain other information (which is
1546	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1869	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1870	$ENV{PERL_ANYEGENT_STRICT}.
		1871
		1872
		1873	=head1 BUGS
		1874
		1875	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1876	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1877	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1878	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1879	pronounced).
1547		1880
1548		1881
1549	=head1 SEE ALSO	1882	=head1 SEE ALSO
1550		1883
1551	Utility functions: L<AnyEvent::Util>.	1884	Utility functions: L<AnyEvent::Util>.
…		…
1568	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	1901	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1569		1902
1570		1903
1571	=head1 AUTHOR	1904	=head1 AUTHOR
1572		1905
1573	Marc Lehmann <schmorp@schmorp.de>	1906	Marc Lehmann <schmorp@schmorp.de>
1574	http://home.schmorp.de/	1907	http://home.schmorp.de/
1575		1908
1576	=cut	1909	=cut
1577		1910
1578	1	1911	1
1579		1912

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC vs. Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC vs.
Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC