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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs.
Revision 1.208 by root, Sun Apr 26 18:12:53 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	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	12	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		13
		14	# one-shot or repeating timers
		15	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		16	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		17
		18	print AnyEvent->now; # prints current event loop time
		19	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		20
		21	# POSIX signal
		22	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		23
		24	# child process exit
		25	my $w = AnyEvent->child (pid => $pid, cb => sub {
		26	my ($pid, $status) = @_;
12	...	27	...
13	});	28	});
14		29
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	30	# called when event loop idle (if applicable)
16	...	31	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		32
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	33	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	34	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	35	$w->recv; # enters "main loop" till $condvar gets ->send
		36	# use a condvar in callback mode:
		37	$w->cb (sub { $_[0]->recv });
		38
		39	=head1 INTRODUCTION/TUTORIAL
		40
		41	This manpage is mainly a reference manual. If you are interested
		42	in a tutorial or some gentle introduction, have a look at the
		43	L<AnyEvent::Intro> manpage.
22		44
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	45	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		46
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	47	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	48	nowadays. So what is different about AnyEvent?
27		49
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	50	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	51	policy> and AnyEvent is I<small and efficient>.
30		52
31	First and foremost, I<AnyEvent is not an event model> itself, it only	53	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	54	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,	55	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,	56	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	57	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	58	cannot change this, but it can hide the differences between those event
		59	loops.
37		60
38	The goal of AnyEvent is to offer module authors the ability to do event	61	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	62	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	63	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	64	module users into the same thing by forcing them to use the same event
42	model you use.	65	model you use.
43		66
44	For modules like POE or IO::Async (which is a total misnomer as it is	67	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	68	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	69	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	70	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	71	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.	72	module are I<also> forced to use the same event loop you use.
50		73
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	74	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	75	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	76	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,	77	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	78	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	79	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	80	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).	81	to AnyEvent, too, so it is future-proof).
59		82
60	In addition to being free of having to use I<the one and only true event	83	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	84	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	85	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	86	follow. AnyEvent, on the other hand, is lean and up to the point, by only
121	These watchers are normal Perl objects with normal Perl lifetime. After	144	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	145	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	146	callback when the event occurs (of course, only when the event model
124	is in control).	147	is in control).
125		148
		149	Note that B<callbacks must not permanently change global variables>
		150	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		151	callbacks must not C<die> >>. The former is good programming practise in
		152	Perl and the latter stems from the fact that exception handling differs
		153	widely between event loops.
		154
126	To disable the watcher you have to destroy it (e.g. by setting the	155	To disable the watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	156	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	157	to it).
129		158
130	All watchers are created by calling a method on the C<AnyEvent> class.	159	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	161	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	162	example), or need to refer to their watcher object in other ways.
134		163
135	An any way to achieve that is this pattern:	164	An any way to achieve that is this pattern:
136		165
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	166	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	167	# you can use $w here, for example to undef it
139	undef $w;	168	undef $w;
140	});	169	});
141		170
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	171	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	172	my variables are only visible after the statement in which they are
144	declared.	173	declared.
145		174
146	=head2 I/O WATCHERS	175	=head2 I/O WATCHERS
147		176
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	177	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	178	with the following mandatory key-value pairs as arguments:
150		179
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	180	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		181	for events (AnyEvent might or might not keep a reference to this file
		182	handle). Note that only file handles pointing to things for which
		183	non-blocking operation makes sense are allowed. This includes sockets,
		184	most character devices, pipes, fifos and so on, but not for example files
		185	or block devices.
		186
152	for events. C<poll> must be a string that is either C<r> or C<w>,	187	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	188	watcher waiting for "r"eadable or "w"ritable events, respectively.
		189
154	respectively. C<cb> is the callback to invoke each time the file handle	190	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		191
157	Although the callback might get passed parameters, their value and	192	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	193	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	194	callbacks cannot use arguments passed to I/O watcher callbacks.
160		195
…		…
164		199
165	Some event loops issue spurious readyness notifications, so you should	200	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	201	always use non-blocking calls when reading/writing from/to your file
167	handles.	202	handles.
168		203
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	204	Example: wait for readability of STDIN, then read a line and disable the
		205	watcher.
		206
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	207	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	208	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	209	warn "read: $input\n";
175	undef $w;	210	undef $w;
176	});	211	});
…		…
186		221
187	Although the callback might get passed parameters, their value and	222	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	223	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	224	callbacks cannot use arguments passed to time watcher callbacks.
190		225
191	The timer callback will be invoked at most once: if you want a repeating	226	The callback will normally be invoked once only. If you specify another
192	timer you have to create a new watcher (this is a limitation by both Tk	227	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	228	callback will be invoked regularly at that interval (in fractional
		229	seconds) after the first invocation. If C<interval> is specified with a
		230	false value, then it is treated as if it were missing.
194		231
195	Example:	232	The callback will be rescheduled before invoking the callback, but no
		233	attempt is done to avoid timer drift in most backends, so the interval is
		234	only approximate.
196		235
197	# fire an event after 7.7 seconds	236	Example: fire an event after 7.7 seconds.
		237
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	238	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	239	warn "timeout\n";
200	});	240	});
201		241
202	# to cancel the timer:	242	# to cancel the timer:
203	undef $w;	243	undef $w;
204		244
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	245	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		246
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	247	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		248	warn "timeout\n";
213	};	249	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		250
218	=head3 TIMING ISSUES	251	=head3 TIMING ISSUES
219		252
220	There are two ways to handle timers: based on real time (relative, "fire	253	There are two ways to handle timers: based on real time (relative, "fire
221	in 10 seconds") and based on wallclock time (absolute, "fire at 12	254	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
233	timers.	266	timers.
234		267
235	AnyEvent always prefers relative timers, if available, matching the	268	AnyEvent always prefers relative timers, if available, matching the
236	AnyEvent API.	269	AnyEvent API.
237		270
		271	AnyEvent has two additional methods that return the "current time":
		272
		273	=over 4
		274
		275	=item AnyEvent->time
		276
		277	This returns the "current wallclock time" as a fractional number of
		278	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		279	return, and the result is guaranteed to be compatible with those).
		280
		281	It progresses independently of any event loop processing, i.e. each call
		282	will check the system clock, which usually gets updated frequently.
		283
		284	=item AnyEvent->now
		285
		286	This also returns the "current wallclock time", but unlike C<time>, above,
		287	this value might change only once per event loop iteration, depending on
		288	the event loop (most return the same time as C<time>, above). This is the
		289	time that AnyEvent's timers get scheduled against.
		290
		291	I<In almost all cases (in all cases if you don't care), this is the
		292	function to call when you want to know the current time.>
		293
		294	This function is also often faster then C<< AnyEvent->time >>, and
		295	thus the preferred method if you want some timestamp (for example,
		296	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		297
		298	The rest of this section is only of relevance if you try to be very exact
		299	with your timing, you can skip it without bad conscience.
		300
		301	For a practical example of when these times differ, consider L<Event::Lib>
		302	and L<EV> and the following set-up:
		303
		304	The event loop is running and has just invoked one of your callback at
		305	time=500 (assume no other callbacks delay processing). In your callback,
		306	you wait a second by executing C<sleep 1> (blocking the process for a
		307	second) and then (at time=501) you create a relative timer that fires
		308	after three seconds.
		309
		310	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		311	both return C<501>, because that is the current time, and the timer will
		312	be scheduled to fire at time=504 (C<501> + C<3>).
		313
		314	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		315	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		316	last event processing phase started. With L<EV>, your timer gets scheduled
		317	to run at time=503 (C<500> + C<3>).
		318
		319	In one sense, L<Event::Lib> is more exact, as it uses the current time
		320	regardless of any delays introduced by event processing. However, most
		321	callbacks do not expect large delays in processing, so this causes a
		322	higher drift (and a lot more system calls to get the current time).
		323
		324	In another sense, L<EV> is more exact, as your timer will be scheduled at
		325	the same time, regardless of how long event processing actually took.
		326
		327	In either case, if you care (and in most cases, you don't), then you
		328	can get whatever behaviour you want with any event loop, by taking the
		329	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		330	account.
		331
		332	=item AnyEvent->now_update
		333
		334	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		335	the current time for each loop iteration (see the discussion of L<<
		336	AnyEvent->now >>, above).
		337
		338	When a callback runs for a long time (or when the process sleeps), then
		339	this "current" time will differ substantially from the real time, which
		340	might affect timers and time-outs.
		341
		342	When this is the case, you can call this method, which will update the
		343	event loop's idea of "current time".
		344
		345	Note that updating the time I<might> cause some events to be handled.
		346
		347	=back
		348
238	=head2 SIGNAL WATCHERS	349	=head2 SIGNAL WATCHERS
239		350
240	You can watch for signals using a signal watcher, C<signal> is the signal	351	You can watch for signals using a signal watcher, C<signal> is the signal
241	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	352	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
242	be invoked whenever a signal occurs.	353	callback to be invoked whenever a signal occurs.
243		354
244	Although the callback might get passed parameters, their value and	355	Although the callback might get passed parameters, their value and
245	presence is undefined and you cannot rely on them. Portable AnyEvent	356	presence is undefined and you cannot rely on them. Portable AnyEvent
246	callbacks cannot use arguments passed to signal watcher callbacks.	357	callbacks cannot use arguments passed to signal watcher callbacks.
247		358
…		…
263	=head2 CHILD PROCESS WATCHERS	374	=head2 CHILD PROCESS WATCHERS
264		375
265	You can also watch on a child process exit and catch its exit status.	376	You can also watch on a child process exit and catch its exit status.
266		377
267	The child process is specified by the C<pid> argument (if set to C<0>, it	378	The child process is specified by the C<pid> argument (if set to C<0>, it
268	watches for any child process exit). The watcher will trigger as often	379	watches for any child process exit). The watcher will triggered only when
269	as status change for the child are received. This works by installing a	380	the child process has finished and an exit status is available, not on
270	signal handler for C<SIGCHLD>. The callback will be called with the pid	381	any trace events (stopped/continued).
271	and exit status (as returned by waitpid), so unlike other watcher types,	382
272	you I<can> rely on child watcher callback arguments.	383	The callback will be called with the pid and exit status (as returned by
		384	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		385	callback arguments.
		386
		387	This watcher type works by installing a signal handler for C<SIGCHLD>,
		388	and since it cannot be shared, nothing else should use SIGCHLD or reap
		389	random child processes (waiting for specific child processes, e.g. inside
		390	C<system>, is just fine).
273		391
274	There is a slight catch to child watchers, however: you usually start them	392	There is a slight catch to child watchers, however: you usually start them
275	I<after> the child process was created, and this means the process could	393	I<after> the child process was created, and this means the process could
276	have exited already (and no SIGCHLD will be sent anymore).	394	have exited already (and no SIGCHLD will be sent anymore).
277		395
…		…
283	AnyEvent program, you I<have> to create at least one watcher before you	401	AnyEvent program, you I<have> to create at least one watcher before you
284	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	402	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
285		403
286	Example: fork a process and wait for it	404	Example: fork a process and wait for it
287		405
288	my $done = AnyEvent->condvar;	406	my $done = AnyEvent->condvar;
289		407
290	my $pid = fork or exit 5;	408	my $pid = fork or exit 5;
291		409
292	my $w = AnyEvent->child (	410	my $w = AnyEvent->child (
293	pid => $pid,	411	pid => $pid,
294	cb => sub {	412	cb => sub {
295	my ($pid, $status) = @_;	413	my ($pid, $status) = @_;
296	warn "pid $pid exited with status $status";	414	warn "pid $pid exited with status $status";
297	$done->send;	415	$done->send;
298	},	416	},
299	);	417	);
300		418
301	# do something else, then wait for process exit	419	# do something else, then wait for process exit
302	$done->recv;	420	$done->recv;
		421
		422	=head2 IDLE WATCHERS
		423
		424	Sometimes there is a need to do something, but it is not so important
		425	to do it instantly, but only when there is nothing better to do. This
		426	"nothing better to do" is usually defined to be "no other events need
		427	attention by the event loop".
		428
		429	Idle watchers ideally get invoked when the event loop has nothing
		430	better to do, just before it would block the process to wait for new
		431	events. Instead of blocking, the idle watcher is invoked.
		432
		433	Most event loops unfortunately do not really support idle watchers (only
		434	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		435	will simply call the callback "from time to time".
		436
		437	Example: read lines from STDIN, but only process them when the
		438	program is otherwise idle:
		439
		440	my @lines; # read data
		441	my $idle_w;
		442	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		443	push @lines, scalar <STDIN>;
		444
		445	# start an idle watcher, if not already done
		446	$idle_w \|\|= AnyEvent->idle (cb => sub {
		447	# handle only one line, when there are lines left
		448	if (my $line = shift @lines) {
		449	print "handled when idle: $line";
		450	} else {
		451	# otherwise disable the idle watcher again
		452	undef $idle_w;
		453	}
		454	});
		455	});
303		456
304	=head2 CONDITION VARIABLES	457	=head2 CONDITION VARIABLES
305		458
306	If you are familiar with some event loops you will know that all of them	459	If you are familiar with some event loops you will know that all of them
307	require you to run some blocking "loop", "run" or similar function that	460	require you to run some blocking "loop", "run" or similar function that
…		…
313	The instrument to do that is called a "condition variable", so called	466	The instrument to do that is called a "condition variable", so called
314	because they represent a condition that must become true.	467	because they represent a condition that must become true.
315		468
316	Condition variables can be created by calling the C<< AnyEvent->condvar	469	Condition variables can be created by calling the C<< AnyEvent->condvar
317	>> method, usually without arguments. The only argument pair allowed is	470	>> method, usually without arguments. The only argument pair allowed is
		471
318	C<cb>, which specifies a callback to be called when the condition variable	472	C<cb>, which specifies a callback to be called when the condition variable
319	becomes true.	473	becomes true, with the condition variable as the first argument (but not
		474	the results).
320		475
321	After creation, the condition variable is "false" until it becomes "true"	476	After creation, the condition variable is "false" until it becomes "true"
322	by calling the C<send> method (or calling the condition variable as if it	477	by calling the C<send> method (or calling the condition variable as if it
323	were a callback, read about the caveats in the description for the C<<	478	were a callback, read about the caveats in the description for the C<<
324	->send >> method).	479	->send >> method).
…		…
380		535
381	my $done = AnyEvent->condvar;	536	my $done = AnyEvent->condvar;
382	my $delay = AnyEvent->timer (after => 5, cb => $done);	537	my $delay = AnyEvent->timer (after => 5, cb => $done);
383	$done->recv;	538	$done->recv;
384		539
		540	Example: Imagine an API that returns a condvar and doesn't support
		541	callbacks. This is how you make a synchronous call, for example from
		542	the main program:
		543
		544	use AnyEvent::CouchDB;
		545
		546	...
		547
		548	my @info = $couchdb->info->recv;
		549
		550	And this is how you would just ste a callback to be called whenever the
		551	results are available:
		552
		553	$couchdb->info->cb (sub {
		554	my @info = $_[0]->recv;
		555	});
		556
385	=head3 METHODS FOR PRODUCERS	557	=head3 METHODS FOR PRODUCERS
386		558
387	These methods should only be used by the producing side, i.e. the	559	These methods should only be used by the producing side, i.e. the
388	code/module that eventually sends the signal. Note that it is also	560	code/module that eventually sends the signal. Note that it is also
389	the producer side which creates the condvar in most cases, but it isn't	561	the producer side which creates the condvar in most cases, but it isn't
…		…
522	=item $bool = $cv->ready	694	=item $bool = $cv->ready
523		695
524	Returns true when the condition is "true", i.e. whether C<send> or	696	Returns true when the condition is "true", i.e. whether C<send> or
525	C<croak> have been called.	697	C<croak> have been called.
526		698
527	=item $cb = $cv->cb ([new callback])	699	=item $cb = $cv->cb ($cb->($cv))
528		700
529	This is a mutator function that returns the callback set and optionally	701	This is a mutator function that returns the callback set and optionally
530	replaces it before doing so.	702	replaces it before doing so.
531		703
532	The callback will be called when the condition becomes "true", i.e. when	704	The callback will be called when the condition becomes "true", i.e. when
533	C<send> or C<croak> are called. Calling C<recv> inside the callback	705	C<send> or C<croak> are called, with the only argument being the condition
534	or at any later time is guaranteed not to block.	706	variable itself. Calling C<recv> inside the callback or at any later time
		707	is guaranteed not to block.
535		708
536	=back	709	=back
537		710
538	=head1 GLOBAL VARIABLES AND FUNCTIONS	711	=head1 GLOBAL VARIABLES AND FUNCTIONS
539		712
…		…
668	=item L<AnyEvent::Util>	841	=item L<AnyEvent::Util>
669		842
670	Contains various utility functions that replace often-used but blocking	843	Contains various utility functions that replace often-used but blocking
671	functions such as C<inet_aton> by event-/callback-based versions.	844	functions such as C<inet_aton> by event-/callback-based versions.
672		845
673	=item L<AnyEvent::Handle>
674
675	Provide read and write buffers and manages watchers for reads and writes.
676
677	=item L<AnyEvent::Socket>	846	=item L<AnyEvent::Socket>
678		847
679	Provides various utility functions for (internet protocol) sockets,	848	Provides various utility functions for (internet protocol) sockets,
680	addresses and name resolution. Also functions to create non-blocking tcp	849	addresses and name resolution. Also functions to create non-blocking tcp
681	connections or tcp servers, with IPv6 and SRV record support and more.	850	connections or tcp servers, with IPv6 and SRV record support and more.
682		851
		852	=item L<AnyEvent::Handle>
		853
		854	Provide read and write buffers, manages watchers for reads and writes,
		855	supports raw and formatted I/O, I/O queued and fully transparent and
		856	non-blocking SSL/TLS.
		857
683	=item L<AnyEvent::DNS>	858	=item L<AnyEvent::DNS>
684		859
685	Provides rich asynchronous DNS resolver capabilities.	860	Provides rich asynchronous DNS resolver capabilities.
686		861
		862	=item L<AnyEvent::HTTP>
		863
		864	A simple-to-use HTTP library that is capable of making a lot of concurrent
		865	HTTP requests.
		866
687	=item L<AnyEvent::HTTPD>	867	=item L<AnyEvent::HTTPD>
688		868
689	Provides a simple web application server framework.	869	Provides a simple web application server framework.
690		870
691	=item L<AnyEvent::FastPing>	871	=item L<AnyEvent::FastPing>
692		872
693	The fastest ping in the west.	873	The fastest ping in the west.
694		874
		875	=item L<AnyEvent::DBI>
		876
		877	Executes L<DBI> requests asynchronously in a proxy process.
		878
		879	=item L<AnyEvent::AIO>
		880
		881	Truly asynchronous I/O, should be in the toolbox of every event
		882	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		883	together.
		884
		885	=item L<AnyEvent::BDB>
		886
		887	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		888	L<BDB> and AnyEvent together.
		889
		890	=item L<AnyEvent::GPSD>
		891
		892	A non-blocking interface to gpsd, a daemon delivering GPS information.
		893
		894	=item L<AnyEvent::IGS>
		895
		896	A non-blocking interface to the Internet Go Server protocol (used by
		897	L<App::IGS>).
		898
695	=item L<Net::IRC3>	899	=item L<AnyEvent::IRC>
696		900
697	AnyEvent based IRC client module family.	901	AnyEvent based IRC client module family (replacing the older Net::IRC3).
698		902
699	=item L<Net::XMPP2>	903	=item L<Net::XMPP2>
700		904
701	AnyEvent based XMPP (Jabber protocol) module family.	905	AnyEvent based XMPP (Jabber protocol) module family.
702		906
…		…
711		915
712	=item L<Coro>	916	=item L<Coro>
713		917
714	Has special support for AnyEvent via L<Coro::AnyEvent>.	918	Has special support for AnyEvent via L<Coro::AnyEvent>.
715		919
716	=item L<AnyEvent::AIO>, L<IO::AIO>
717
718	Truly asynchronous I/O, should be in the toolbox of every event
719	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
720	together.
721
722	=item L<AnyEvent::BDB>, L<BDB>
723
724	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
725	IO::AIO and AnyEvent together.
726
727	=item L<IO::Lambda>	920	=item L<IO::Lambda>
728		921
729	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	922	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
730		923
731	=back	924	=back
…		…
733	=cut	926	=cut
734		927
735	package AnyEvent;	928	package AnyEvent;
736		929
737	no warnings;	930	no warnings;
738	use strict;	931	use strict qw(vars subs);
739		932
740	use Carp;	933	use Carp;
741		934
742	our $VERSION = '4.05';	935	our $VERSION = 4.4;
743	our $MODEL;	936	our $MODEL;
744		937
745	our $AUTOLOAD;	938	our $AUTOLOAD;
746	our @ISA;	939	our @ISA;
747		940
…		…
779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	972	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
780	[Wx:: => AnyEvent::Impl::POE::],	973	[Wx:: => AnyEvent::Impl::POE::],
781	[Prima:: => AnyEvent::Impl::POE::],	974	[Prima:: => AnyEvent::Impl::POE::],
782	);	975	);
783		976
784	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	977	our %method = map +($_ => 1),
		978	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
785		979
786	our @post_detect;	980	our @post_detect;
787		981
788	sub post_detect(&) {	982	sub post_detect(&) {
789	my ($cb) = @_;	983	my ($cb) = @_;
…		…
794	1	988	1
795	} else {	989	} else {
796	push @post_detect, $cb;	990	push @post_detect, $cb;
797		991
798	defined wantarray	992	defined wantarray
799	? bless \$cb, "AnyEvent::Util::PostDetect"	993	? bless \$cb, "AnyEvent::Util::postdetect"
800	: ()	994	: ()
801	}	995	}
802	}	996	}
803		997
804	sub AnyEvent::Util::PostDetect::DESTROY {	998	sub AnyEvent::Util::postdetect::DESTROY {
805	@post_detect = grep $_ != ${$_[0]}, @post_detect;	999	@post_detect = grep $_ != ${$_[0]}, @post_detect;
806	}	1000	}
807		1001
808	sub detect() {	1002	sub detect() {
809	unless ($MODEL) {	1003	unless ($MODEL) {
…		…
846	last;	1040	last;
847	}	1041	}
848	}	1042	}
849		1043
850	$MODEL	1044	$MODEL
851	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1045	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
852	}	1046	}
853	}	1047	}
854		1048
		1049	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1050
855	unshift @ISA, $MODEL;	1051	unshift @ISA, $MODEL;
856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1052
		1053	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
857		1054
858	(shift @post_detect)->() while @post_detect;	1055	(shift @post_detect)->() while @post_detect;
859	}	1056	}
860		1057
861	$MODEL	1058	$MODEL
…		…
871		1068
872	my $class = shift;	1069	my $class = shift;
873	$class->$func (@_);	1070	$class->$func (@_);
874	}	1071	}
875		1072
		1073	# utility function to dup a filehandle. this is used by many backends
		1074	# to support binding more than one watcher per filehandle (they usually
		1075	# allow only one watcher per fd, so we dup it to get a different one).
		1076	sub _dupfh($$$$) {
		1077	my ($poll, $fh, $r, $w) = @_;
		1078
		1079	# cygwin requires the fh mode to be matching, unix doesn't
		1080	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1081	: $poll eq "w" ? ($w, ">")
		1082	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1083
		1084	open my $fh2, "$mode&" . fileno $fh
		1085	or die "cannot dup() filehandle: $!,";
		1086
		1087	# we assume CLOEXEC is already set by perl in all important cases
		1088
		1089	($fh2, $rw)
		1090	}
		1091
876	package AnyEvent::Base;	1092	package AnyEvent::Base;
877		1093
		1094	# default implementations for many methods
		1095
		1096	BEGIN {
		1097	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1098	*_time = \&Time::HiRes::time;
		1099	# if (eval "use POSIX (); (POSIX::times())...
		1100	} else {
		1101	*_time = sub { time }; # epic fail
		1102	}
		1103	}
		1104
		1105	sub time { _time }
		1106	sub now { _time }
		1107	sub now_update { }
		1108
878	# default implementation for ->condvar	1109	# default implementation for ->condvar
879		1110
880	sub condvar {	1111	sub condvar {
881	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1112	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
882	}	1113	}
883		1114
884	# default implementation for ->signal	1115	# default implementation for ->signal
885		1116
886	our %SIG_CB;	1117	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1118
		1119	sub _signal_exec {
		1120	sysread $SIGPIPE_R, my $dummy, 4;
		1121
		1122	while (%SIG_EV) {
		1123	for (keys %SIG_EV) {
		1124	delete $SIG_EV{$_};
		1125	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1126	}
		1127	}
		1128	}
887		1129
888	sub signal {	1130	sub signal {
889	my (undef, %arg) = @_;	1131	my (undef, %arg) = @_;
890		1132
		1133	unless ($SIGPIPE_R) {
		1134	require Fcntl;
		1135
		1136	if (AnyEvent::WIN32) {
		1137	require AnyEvent::Util;
		1138
		1139	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1140	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1141	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1142	} else {
		1143	pipe $SIGPIPE_R, $SIGPIPE_W;
		1144	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1145	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1146	}
		1147
		1148	$SIGPIPE_R
		1149	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154
		1155	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1156	}
		1157
891	my $signal = uc $arg{signal}	1158	my $signal = uc $arg{signal}
892	or Carp::croak "required option 'signal' is missing";	1159	or Carp::croak "required option 'signal' is missing";
893		1160
894	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1161	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
895	$SIG{$signal} \|\|= sub {	1162	$SIG{$signal} \|\|= sub {
896	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1163	local $!;
		1164	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1165	undef $SIG_EV{$signal};
897	};	1166	};
898		1167
899	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1168	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
900	}	1169	}
901		1170
902	sub AnyEvent::Base::Signal::DESTROY {	1171	sub AnyEvent::Base::signal::DESTROY {
903	my ($signal, $cb) = @{$_[0]};	1172	my ($signal, $cb) = @{$_[0]};
904		1173
905	delete $SIG_CB{$signal}{$cb};	1174	delete $SIG_CB{$signal}{$cb};
906		1175
907	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1176	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
908	}	1177	}
909		1178
910	# default implementation for ->child	1179	# default implementation for ->child
911		1180
912	our %PID_CB;	1181	our %PID_CB;
…		…
948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1217	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
949	# child could be a zombie already, so make at least one round	1218	# child could be a zombie already, so make at least one round
950	&_sigchld;	1219	&_sigchld;
951	}	1220	}
952		1221
953	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1222	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
954	}	1223	}
955		1224
956	sub AnyEvent::Base::Child::DESTROY {	1225	sub AnyEvent::Base::child::DESTROY {
957	my ($pid, $cb) = @{$_[0]};	1226	my ($pid, $cb) = @{$_[0]};
958		1227
959	delete $PID_CB{$pid}{$cb};	1228	delete $PID_CB{$pid}{$cb};
960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1229	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
961		1230
962	undef $CHLD_W unless keys %PID_CB;	1231	undef $CHLD_W unless keys %PID_CB;
		1232	}
		1233
		1234	# idle emulation is done by simply using a timer, regardless
		1235	# of whether the proces sis idle or not, and not letting
		1236	# the callback use more than 50% of the time.
		1237	sub idle {
		1238	my (undef, %arg) = @_;
		1239
		1240	my ($cb, $w, $rcb) = $arg{cb};
		1241
		1242	$rcb = sub {
		1243	if ($cb) {
		1244	$w = _time;
		1245	&$cb;
		1246	$w = _time - $w;
		1247
		1248	# never use more then 50% of the time for the idle watcher,
		1249	# within some limits
		1250	$w = 0.0001 if $w < 0.0001;
		1251	$w = 5 if $w > 5;
		1252
		1253	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1254	} else {
		1255	# clean up...
		1256	undef $w;
		1257	undef $rcb;
		1258	}
		1259	};
		1260
		1261	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1262
		1263	bless \\$cb, "AnyEvent::Base::idle"
		1264	}
		1265
		1266	sub AnyEvent::Base::idle::DESTROY {
		1267	undef $${$_[0]};
963	}	1268	}
964		1269
965	package AnyEvent::CondVar;	1270	package AnyEvent::CondVar;
966		1271
967	our @ISA = AnyEvent::CondVar::Base::;	1272	our @ISA = AnyEvent::CondVar::Base::;
…		…
1019	}	1324	}
1020		1325
1021	# undocumented/compatibility with pre-3.4	1326	# undocumented/compatibility with pre-3.4
1022	*broadcast = \&send;	1327	*broadcast = \&send;
1023	*wait = \&_wait;	1328	*wait = \&_wait;
		1329
		1330	=head1 ERROR AND EXCEPTION HANDLING
		1331
		1332	In general, AnyEvent does not do any error handling - it relies on the
		1333	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1334	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1335	checking of all AnyEvent methods, however, which is highly useful during
		1336	development.
		1337
		1338	As for exception handling (i.e. runtime errors and exceptions thrown while
		1339	executing a callback), this is not only highly event-loop specific, but
		1340	also not in any way wrapped by this module, as this is the job of the main
		1341	program.
		1342
		1343	The pure perl event loop simply re-throws the exception (usually
		1344	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1345	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1346	so on.
		1347
		1348	=head1 ENVIRONMENT VARIABLES
		1349
		1350	The following environment variables are used by this module or its
		1351	submodules:
		1352
		1353	=over 4
		1354
		1355	=item C<PERL_ANYEVENT_VERBOSE>
		1356
		1357	By default, AnyEvent will be completely silent except in fatal
		1358	conditions. You can set this environment variable to make AnyEvent more
		1359	talkative.
		1360
		1361	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1362	conditions, such as not being able to load the event model specified by
		1363	C<PERL_ANYEVENT_MODEL>.
		1364
		1365	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1366	model it chooses.
		1367
		1368	=item C<PERL_ANYEVENT_STRICT>
		1369
		1370	AnyEvent does not do much argument checking by default, as thorough
		1371	argument checking is very costly. Setting this variable to a true value
		1372	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1373	check the arguments passed to most method calls. If it finds any problems
		1374	it will croak.
		1375
		1376	In other words, enables "strict" mode.
		1377
		1378	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1379	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1380	developing programs can be very useful, however.
		1381
		1382	=item C<PERL_ANYEVENT_MODEL>
		1383
		1384	This can be used to specify the event model to be used by AnyEvent, before
		1385	auto detection and -probing kicks in. It must be a string consisting
		1386	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1387	and the resulting module name is loaded and if the load was successful,
		1388	used as event model. If it fails to load AnyEvent will proceed with
		1389	auto detection and -probing.
		1390
		1391	This functionality might change in future versions.
		1392
		1393	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1394	could start your program like this:
		1395
		1396	PERL_ANYEVENT_MODEL=Perl perl ...
		1397
		1398	=item C<PERL_ANYEVENT_PROTOCOLS>
		1399
		1400	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1401	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1402	of auto probing).
		1403
		1404	Must be set to a comma-separated list of protocols or address families,
		1405	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1406	used, and preference will be given to protocols mentioned earlier in the
		1407	list.
		1408
		1409	This variable can effectively be used for denial-of-service attacks
		1410	against local programs (e.g. when setuid), although the impact is likely
		1411	small, as the program has to handle conenction and other failures anyways.
		1412
		1413	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1414	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1415	- only support IPv4, never try to resolve or contact IPv6
		1416	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1417	IPv6, but prefer IPv6 over IPv4.
		1418
		1419	=item C<PERL_ANYEVENT_EDNS0>
		1420
		1421	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1422	for DNS. This extension is generally useful to reduce DNS traffic, but
		1423	some (broken) firewalls drop such DNS packets, which is why it is off by
		1424	default.
		1425
		1426	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1427	EDNS0 in its DNS requests.
		1428
		1429	=item C<PERL_ANYEVENT_MAX_FORKS>
		1430
		1431	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1432	will create in parallel.
		1433
		1434	=back
1024		1435
1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1436	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1026		1437
1027	This is an advanced topic that you do not normally need to use AnyEvent in	1438	This is an advanced topic that you do not normally need to use AnyEvent in
1028	a module. This section is only of use to event loop authors who want to	1439	a module. This section is only of use to event loop authors who want to
…		…
1062		1473
1063	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1474	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1064	condition variables: code blocking while waiting for a condition will	1475	condition variables: code blocking while waiting for a condition will
1065	C<die>. This still works with most modules/usages, and blocking calls must	1476	C<die>. This still works with most modules/usages, and blocking calls must
1066	not be done in an interactive application, so it makes sense.	1477	not be done in an interactive application, so it makes sense.
1067
1068	=head1 ENVIRONMENT VARIABLES
1069
1070	The following environment variables are used by this module:
1071
1072	=over 4
1073
1074	=item C<PERL_ANYEVENT_VERBOSE>
1075
1076	By default, AnyEvent will be completely silent except in fatal
1077	conditions. You can set this environment variable to make AnyEvent more
1078	talkative.
1079
1080	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1081	conditions, such as not being able to load the event model specified by
1082	C<PERL_ANYEVENT_MODEL>.
1083
1084	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1085	model it chooses.
1086
1087	=item C<PERL_ANYEVENT_MODEL>
1088
1089	This can be used to specify the event model to be used by AnyEvent, before
1090	auto detection and -probing kicks in. It must be a string consisting
1091	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1092	and the resulting module name is loaded and if the load was successful,
1093	used as event model. If it fails to load AnyEvent will proceed with
1094	auto detection and -probing.
1095
1096	This functionality might change in future versions.
1097
1098	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1099	could start your program like this:
1100
1101	PERL_ANYEVENT_MODEL=Perl perl ...
1102
1103	=item C<PERL_ANYEVENT_PROTOCOLS>
1104
1105	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1106	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1107	of auto probing).
1108
1109	Must be set to a comma-separated list of protocols or address families,
1110	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1111	used, and preference will be given to protocols mentioned earlier in the
1112	list.
1113
1114	This variable can effectively be used for denial-of-service attacks
1115	against local programs (e.g. when setuid), although the impact is likely
1116	small, as the program has to handle connection errors already-
1117
1118	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1119	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1120	- only support IPv4, never try to resolve or contact IPv6
1121	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1122	IPv6, but prefer IPv6 over IPv4.
1123
1124	=item C<PERL_ANYEVENT_EDNS0>
1125
1126	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1127	for DNS. This extension is generally useful to reduce DNS traffic, but
1128	some (broken) firewalls drop such DNS packets, which is why it is off by
1129	default.
1130
1131	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1132	EDNS0 in its DNS requests.
1133
1134	=item C<PERL_ANYEVENT_MAX_FORKS>
1135
1136	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1137	will create in parallel.
1138
1139	=back
1140		1478
1141	=head1 EXAMPLE PROGRAM	1479	=head1 EXAMPLE PROGRAM
1142		1480
1143	The following program uses an I/O watcher to read data from STDIN, a timer	1481	The following program uses an I/O watcher to read data from STDIN, a timer
1144	to display a message once per second, and a condition variable to quit the	1482	to display a message once per second, and a condition variable to quit the
…		…
1338	watcher.	1676	watcher.
1339		1677
1340	=head3 Results	1678	=head3 Results
1341		1679
1342	name watchers bytes create invoke destroy comment	1680	name watchers bytes create invoke destroy comment
1343	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1681	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1344	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1682	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1345	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1683	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1346	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1684	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1347	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1685	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1348	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1686	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1349	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1687	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1350	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1688	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1351	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1689	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1352	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1690	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1353		1691
1354	=head3 Discussion	1692	=head3 Discussion
1355		1693
1356	The benchmark does I<not> measure scalability of the event loop very	1694	The benchmark does I<not> measure scalability of the event loop very
1357	well. For example, a select-based event loop (such as the pure perl one)	1695	well. For example, a select-based event loop (such as the pure perl one)
…		…
1559	watchers, as the management overhead dominates.	1897	watchers, as the management overhead dominates.
1560		1898
1561	=back	1899	=back
1562		1900
1563		1901
		1902	=head1 SIGNALS
		1903
		1904	AnyEvent currently installs handlers for these signals:
		1905
		1906	=over 4
		1907
		1908	=item SIGCHLD
		1909
		1910	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1911	emulation for event loops that do not support them natively. Also, some
		1912	event loops install a similar handler.
		1913
		1914	=item SIGPIPE
		1915
		1916	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1917	when AnyEvent gets loaded.
		1918
		1919	The rationale for this is that AnyEvent users usually do not really depend
		1920	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1921	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1922	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1923	some random socket.
		1924
		1925	The rationale for installing a no-op handler as opposed to ignoring it is
		1926	that this way, the handler will be restored to defaults on exec.
		1927
		1928	Feel free to install your own handler, or reset it to defaults.
		1929
		1930	=back
		1931
		1932	=cut
		1933
		1934	$SIG{PIPE} = sub { }
		1935	unless defined $SIG{PIPE};
		1936
		1937
1564	=head1 FORK	1938	=head1 FORK
1565		1939
1566	Most event libraries are not fork-safe. The ones who are usually are	1940	Most event libraries are not fork-safe. The ones who are usually are
1567	because they rely on inefficient but fork-safe C<select> or C<poll>	1941	because they rely on inefficient but fork-safe C<select> or C<poll>
1568	calls. Only L<EV> is fully fork-aware.	1942	calls. Only L<EV> is fully fork-aware.
…		…
1581	specified in the variable.	1955	specified in the variable.
1582		1956
1583	You can make AnyEvent completely ignore this variable by deleting it	1957	You can make AnyEvent completely ignore this variable by deleting it
1584	before the first watcher gets created, e.g. with a C<BEGIN> block:	1958	before the first watcher gets created, e.g. with a C<BEGIN> block:
1585		1959
1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1960	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1587		1961
1588	use AnyEvent;	1962	use AnyEvent;
1589		1963
1590	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1964	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1591	be used to probe what backend is used and gain other information (which is	1965	be used to probe what backend is used and gain other information (which is
1592	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1966	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1967	$ENV{PERL_ANYEGENT_STRICT}.
		1968
		1969
		1970	=head1 BUGS
		1971
		1972	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1973	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1974	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1975	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1976	pronounced).
1593		1977
1594		1978
1595	=head1 SEE ALSO	1979	=head1 SEE ALSO
1596		1980
1597	Utility functions: L<AnyEvent::Util>.	1981	Utility functions: L<AnyEvent::Util>.
…		…
1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	1998	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1615		1999
1616		2000
1617	=head1 AUTHOR	2001	=head1 AUTHOR
1618		2002
1619	Marc Lehmann <schmorp@schmorp.de>	2003	Marc Lehmann <schmorp@schmorp.de>
1620	http://home.schmorp.de/	2004	http://home.schmorp.de/
1621		2005
1622	=cut	2006	=cut
1623		2007
1624	1	2008	1
1625		2009

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs. Revision 1.208 by root, Sun Apr 26 18:12:53 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC vs.
Revision 1.208 by root, Sun Apr 26 18:12:53 2009 UTC