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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.148 by root, Sat May 31 00:40:16 2008 UTC vs.
Revision 1.216 by root, Tue Jun 23 12:21:34 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 and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
33		50
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
36		53
37	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
43		61
44	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
48	model you use.	66	model you use.
49		67
50	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
56		74
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
65		83
66	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
129	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
130	is in control).	148	is in control).
131		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
132	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
133	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	158	to it).
135		159
136	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
138	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
139	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
140		164
141	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
142		166
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
145	undef $w;	169	undef $w;
146	});	170	});
147		171
148	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
149	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
150	declared.	174	declared.
151		175
152	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
153		177
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
156		180
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
158	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
160	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		192
163	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
166		196
…		…
170		200
171	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
173	handles.	203	handles.
174		204
175	Example:
176
177	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	210	warn "read: $input\n";
181	undef $w;	211	undef $w;
182	});	212	});
…		…
192		222
193	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
196		226
197	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
198	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
200		232
201	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
202		236
203	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	240	warn "timeout\n";
206	});	241	});
207		242
208	# to cancel the timer:	243	# to cancel the timer:
209	undef $w;	244	undef $w;
210		245
211	Example 2:
212
213	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
214	my $w;
215		247
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
219	};	250	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		251
224	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
225		253
226	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
227	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
300	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
301	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	331	account.
304		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
305	=back	348	=back
306		349
307	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
308		351
309	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
310	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
312		355
313	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
316		359
…		…
332	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
333		376
334	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
335		378
336	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
337	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
338	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
339	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
340	and exit status (as returned by waitpid), so unlike other watcher types,	383
341	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
342		392
343	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
344	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
346		396
…		…
352	AnyEvent program, you I<have> to create at least one watcher before you	402	AnyEvent program, you I<have> to create at least one watcher before you
353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
354		404
355	Example: fork a process and wait for it	405	Example: fork a process and wait for it
356		406
357	my $done = AnyEvent->condvar;	407	my $done = AnyEvent->condvar;
358		408
359	my $pid = fork or exit 5;	409	my $pid = fork or exit 5;
360		410
361	my $w = AnyEvent->child (	411	my $w = AnyEvent->child (
362	pid => $pid,	412	pid => $pid,
363	cb => sub {	413	cb => sub {
364	my ($pid, $status) = @_;	414	my ($pid, $status) = @_;
365	warn "pid $pid exited with status $status";	415	warn "pid $pid exited with status $status";
366	$done->send;	416	$done->send;
367	},	417	},
368	);	418	);
369		419
370	# do something else, then wait for process exit	420	# do something else, then wait for process exit
371	$done->recv;	421	$done->recv;
		422
		423	=head2 IDLE WATCHERS
		424
		425	Sometimes there is a need to do something, but it is not so important
		426	to do it instantly, but only when there is nothing better to do. This
		427	"nothing better to do" is usually defined to be "no other events need
		428	attention by the event loop".
		429
		430	Idle watchers ideally get invoked when the event loop has nothing
		431	better to do, just before it would block the process to wait for new
		432	events. Instead of blocking, the idle watcher is invoked.
		433
		434	Most event loops unfortunately do not really support idle watchers (only
		435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		436	will simply call the callback "from time to time".
		437
		438	Example: read lines from STDIN, but only process them when the
		439	program is otherwise idle:
		440
		441	my @lines; # read data
		442	my $idle_w;
		443	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		444	push @lines, scalar <STDIN>;
		445
		446	# start an idle watcher, if not already done
		447	$idle_w \|\|= AnyEvent->idle (cb => sub {
		448	# handle only one line, when there are lines left
		449	if (my $line = shift @lines) {
		450	print "handled when idle: $line";
		451	} else {
		452	# otherwise disable the idle watcher again
		453	undef $idle_w;
		454	}
		455	});
		456	});
372		457
373	=head2 CONDITION VARIABLES	458	=head2 CONDITION VARIABLES
374		459
375	If you are familiar with some event loops you will know that all of them	460	If you are familiar with some event loops you will know that all of them
376	require you to run some blocking "loop", "run" or similar function that	461	require you to run some blocking "loop", "run" or similar function that
…		…
382	The instrument to do that is called a "condition variable", so called	467	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	468	because they represent a condition that must become true.
384		469
385	Condition variables can be created by calling the C<< AnyEvent->condvar	470	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	471	>> method, usually without arguments. The only argument pair allowed is
		472
387	C<cb>, which specifies a callback to be called when the condition variable	473	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	474	becomes true, with the condition variable as the first argument (but not
		475	the results).
389		476
390	After creation, the condition variable is "false" until it becomes "true"	477	After creation, the condition variable is "false" until it becomes "true"
391	by calling the C<send> method (or calling the condition variable as if it	478	by calling the C<send> method (or calling the condition variable as if it
392	were a callback, read about the caveats in the description for the C<<	479	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	480	->send >> method).
…		…
449		536
450	my $done = AnyEvent->condvar;	537	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	538	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	539	$done->recv;
453		540
		541	Example: Imagine an API that returns a condvar and doesn't support
		542	callbacks. This is how you make a synchronous call, for example from
		543	the main program:
		544
		545	use AnyEvent::CouchDB;
		546
		547	...
		548
		549	my @info = $couchdb->info->recv;
		550
		551	And this is how you would just ste a callback to be called whenever the
		552	results are available:
		553
		554	$couchdb->info->cb (sub {
		555	my @info = $_[0]->recv;
		556	});
		557
454	=head3 METHODS FOR PRODUCERS	558	=head3 METHODS FOR PRODUCERS
455		559
456	These methods should only be used by the producing side, i.e. the	560	These methods should only be used by the producing side, i.e. the
457	code/module that eventually sends the signal. Note that it is also	561	code/module that eventually sends the signal. Note that it is also
458	the producer side which creates the condvar in most cases, but it isn't	562	the producer side which creates the condvar in most cases, but it isn't
…		…
591	=item $bool = $cv->ready	695	=item $bool = $cv->ready
592		696
593	Returns true when the condition is "true", i.e. whether C<send> or	697	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	698	C<croak> have been called.
595		699
596	=item $cb = $cv->cb ([new callback])	700	=item $cb = $cv->cb ($cb->($cv))
597		701
598	This is a mutator function that returns the callback set and optionally	702	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	703	replaces it before doing so.
600		704
601	The callback will be called when the condition becomes "true", i.e. when	705	The callback will be called when the condition becomes "true", i.e. when
602	C<send> or C<croak> are called. Calling C<recv> inside the callback	706	C<send> or C<croak> are called, with the only argument being the condition
603	or at any later time is guaranteed not to block.	707	variable itself. Calling C<recv> inside the callback or at any later time
		708	is guaranteed not to block.
604		709
605	=back	710	=back
606		711
607	=head1 GLOBAL VARIABLES AND FUNCTIONS	712	=head1 GLOBAL VARIABLES AND FUNCTIONS
608		713
…		…
737	=item L<AnyEvent::Util>	842	=item L<AnyEvent::Util>
738		843
739	Contains various utility functions that replace often-used but blocking	844	Contains various utility functions that replace often-used but blocking
740	functions such as C<inet_aton> by event-/callback-based versions.	845	functions such as C<inet_aton> by event-/callback-based versions.
741		846
742	=item L<AnyEvent::Handle>
743
744	Provide read and write buffers and manages watchers for reads and writes.
745
746	=item L<AnyEvent::Socket>	847	=item L<AnyEvent::Socket>
747		848
748	Provides various utility functions for (internet protocol) sockets,	849	Provides various utility functions for (internet protocol) sockets,
749	addresses and name resolution. Also functions to create non-blocking tcp	850	addresses and name resolution. Also functions to create non-blocking tcp
750	connections or tcp servers, with IPv6 and SRV record support and more.	851	connections or tcp servers, with IPv6 and SRV record support and more.
751		852
		853	=item L<AnyEvent::Handle>
		854
		855	Provide read and write buffers, manages watchers for reads and writes,
		856	supports raw and formatted I/O, I/O queued and fully transparent and
		857	non-blocking SSL/TLS.
		858
752	=item L<AnyEvent::DNS>	859	=item L<AnyEvent::DNS>
753		860
754	Provides rich asynchronous DNS resolver capabilities.	861	Provides rich asynchronous DNS resolver capabilities.
755		862
		863	=item L<AnyEvent::HTTP>
		864
		865	A simple-to-use HTTP library that is capable of making a lot of concurrent
		866	HTTP requests.
		867
756	=item L<AnyEvent::HTTPD>	868	=item L<AnyEvent::HTTPD>
757		869
758	Provides a simple web application server framework.	870	Provides a simple web application server framework.
759		871
760	=item L<AnyEvent::FastPing>	872	=item L<AnyEvent::FastPing>
761		873
762	The fastest ping in the west.	874	The fastest ping in the west.
763		875
		876	=item L<AnyEvent::DBI>
		877
		878	Executes L<DBI> requests asynchronously in a proxy process.
		879
		880	=item L<AnyEvent::AIO>
		881
		882	Truly asynchronous I/O, should be in the toolbox of every event
		883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		884	together.
		885
		886	=item L<AnyEvent::BDB>
		887
		888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		889	L<BDB> and AnyEvent together.
		890
		891	=item L<AnyEvent::GPSD>
		892
		893	A non-blocking interface to gpsd, a daemon delivering GPS information.
		894
		895	=item L<AnyEvent::IGS>
		896
		897	A non-blocking interface to the Internet Go Server protocol (used by
		898	L<App::IGS>).
		899
764	=item L<Net::IRC3>	900	=item L<AnyEvent::IRC>
765		901
766	AnyEvent based IRC client module family.	902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
767		903
768	=item L<Net::XMPP2>	904	=item L<Net::XMPP2>
769		905
770	AnyEvent based XMPP (Jabber protocol) module family.	906	AnyEvent based XMPP (Jabber protocol) module family.
771		907
…		…
780		916
781	=item L<Coro>	917	=item L<Coro>
782		918
783	Has special support for AnyEvent via L<Coro::AnyEvent>.	919	Has special support for AnyEvent via L<Coro::AnyEvent>.
784		920
785	=item L<AnyEvent::AIO>, L<IO::AIO>
786
787	Truly asynchronous I/O, should be in the toolbox of every event
788	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
789	together.
790
791	=item L<AnyEvent::BDB>, L<BDB>
792
793	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
794	IO::AIO and AnyEvent together.
795
796	=item L<IO::Lambda>	921	=item L<IO::Lambda>
797		922
798	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
799		924
800	=back	925	=back
…		…
802	=cut	927	=cut
803		928
804	package AnyEvent;	929	package AnyEvent;
805		930
806	no warnings;	931	no warnings;
807	use strict;	932	use strict qw(vars subs);
808		933
809	use Carp;	934	use Carp;
810		935
811	our $VERSION = 4.11;	936	our $VERSION = 4.411;
812	our $MODEL;	937	our $MODEL;
813		938
814	our $AUTOLOAD;	939	our $AUTOLOAD;
815	our @ISA;	940	our @ISA;
816		941
817	our @REGISTRY;	942	our @REGISTRY;
818		943
819	our $WIN32;	944	our $WIN32;
820		945
821	BEGIN {	946	BEGIN {
822	my $win32 = ! ! ($^O =~ /mswin32/i);	947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
823	eval "sub WIN32(){ $win32 }";	948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		949
		950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		951	if ${^TAINT};
824	}	952	}
825		953
826	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
827		955
828	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	956	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
848	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
849	[Wx:: => AnyEvent::Impl::POE::],	977	[Wx:: => AnyEvent::Impl::POE::],
850	[Prima:: => AnyEvent::Impl::POE::],	978	[Prima:: => AnyEvent::Impl::POE::],
851	);	979	);
852		980
853	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	981	our %method = map +($_ => 1),
		982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
854		983
855	our @post_detect;	984	our @post_detect;
856		985
857	sub post_detect(&) {	986	sub post_detect(&) {
858	my ($cb) = @_;	987	my ($cb) = @_;
…		…
863	1	992	1
864	} else {	993	} else {
865	push @post_detect, $cb;	994	push @post_detect, $cb;
866		995
867	defined wantarray	996	defined wantarray
868	? bless \$cb, "AnyEvent::Util::PostDetect"	997	? bless \$cb, "AnyEvent::Util::postdetect"
869	: ()	998	: ()
870	}	999	}
871	}	1000	}
872		1001
873	sub AnyEvent::Util::PostDetect::DESTROY {	1002	sub AnyEvent::Util::postdetect::DESTROY {
874	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
875	}	1004	}
876		1005
877	sub detect() {	1006	sub detect() {
878	unless ($MODEL) {	1007	unless ($MODEL) {
…		…
915	last;	1044	last;
916	}	1045	}
917	}	1046	}
918		1047
919	$MODEL	1048	$MODEL
920	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
921	}	1050	}
922	}	1051	}
923		1052
		1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1054
924	unshift @ISA, $MODEL;	1055	unshift @ISA, $MODEL;
925	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1056
		1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
926		1058
927	(shift @post_detect)->() while @post_detect;	1059	(shift @post_detect)->() while @post_detect;
928	}	1060	}
929		1061
930	$MODEL	1062	$MODEL
…		…
940		1072
941	my $class = shift;	1073	my $class = shift;
942	$class->$func (@_);	1074	$class->$func (@_);
943	}	1075	}
944		1076
		1077	# utility function to dup a filehandle. this is used by many backends
		1078	# to support binding more than one watcher per filehandle (they usually
		1079	# allow only one watcher per fd, so we dup it to get a different one).
		1080	sub _dupfh($$$$) {
		1081	my ($poll, $fh, $r, $w) = @_;
		1082
		1083	# cygwin requires the fh mode to be matching, unix doesn't
		1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1085	: $poll eq "w" ? ($w, ">")
		1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1087
		1088	open my $fh2, "$mode&" . fileno $fh
		1089	or die "cannot dup() filehandle: $!,";
		1090
		1091	# we assume CLOEXEC is already set by perl in all important cases
		1092
		1093	($fh2, $rw)
		1094	}
		1095
945	package AnyEvent::Base;	1096	package AnyEvent::Base;
946		1097
947	# default implementation for now and time	1098	# default implementations for many methods
948		1099
949	use Time::HiRes ();	1100	BEGIN {
		1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1102	*_time = \&Time::HiRes::time;
		1103	# if (eval "use POSIX (); (POSIX::times())...
		1104	} else {
		1105	*_time = sub { time }; # epic fail
		1106	}
		1107	}
950		1108
951	sub time { Time::HiRes::time }	1109	sub time { _time }
952	sub now { Time::HiRes::time }	1110	sub now { _time }
		1111	sub now_update { }
953		1112
954	# default implementation for ->condvar	1113	# default implementation for ->condvar
955		1114
956	sub condvar {	1115	sub condvar {
957	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
958	}	1117	}
959		1118
960	# default implementation for ->signal	1119	# default implementation for ->signal
961		1120
962	our %SIG_CB;	1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1122
		1123	sub _signal_exec {
		1124	sysread $SIGPIPE_R, my $dummy, 4;
		1125
		1126	while (%SIG_EV) {
		1127	for (keys %SIG_EV) {
		1128	delete $SIG_EV{$_};
		1129	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1130	}
		1131	}
		1132	}
963		1133
964	sub signal {	1134	sub signal {
965	my (undef, %arg) = @_;	1135	my (undef, %arg) = @_;
966		1136
		1137	unless ($SIGPIPE_R) {
		1138	require Fcntl;
		1139
		1140	if (AnyEvent::WIN32) {
		1141	require AnyEvent::Util;
		1142
		1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1146	} else {
		1147	pipe $SIGPIPE_R, $SIGPIPE_W;
		1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		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
		1156	$SIGPIPE_R
		1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1158
		1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1160	}
		1161
967	my $signal = uc $arg{signal}	1162	my $signal = uc $arg{signal}
968	or Carp::croak "required option 'signal' is missing";	1163	or Carp::croak "required option 'signal' is missing";
969		1164
970	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
971	$SIG{$signal} \|\|= sub {	1166	$SIG{$signal} \|\|= sub {
972	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1167	local $!;
		1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1169	undef $SIG_EV{$signal};
973	};	1170	};
974		1171
975	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
976	}	1173	}
977		1174
978	sub AnyEvent::Base::Signal::DESTROY {	1175	sub AnyEvent::Base::signal::DESTROY {
979	my ($signal, $cb) = @{$_[0]};	1176	my ($signal, $cb) = @{$_[0]};
980		1177
981	delete $SIG_CB{$signal}{$cb};	1178	delete $SIG_CB{$signal}{$cb};
982		1179
		1180	# delete doesn't work with older perls - they then
		1181	# print weird messages, or just unconditionally exit
		1182	# instead of getting the default action.
983	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
984	}	1184	}
985		1185
986	# default implementation for ->child	1186	# default implementation for ->child
987		1187
988	our %PID_CB;	1188	our %PID_CB;
989	our $CHLD_W;	1189	our $CHLD_W;
990	our $CHLD_DELAY_W;	1190	our $CHLD_DELAY_W;
991	our $PID_IDLE;
992	our $WNOHANG;	1191	our $WNOHANG;
993		1192
994	sub _child_wait {	1193	sub _sigchld {
995	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
996	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
997	(values %{ $PID_CB{0} \|\| {} });	1196	(values %{ $PID_CB{0} \|\| {} });
998	}	1197	}
999
1000	undef $PID_IDLE;
1001	}
1002
1003	sub _sigchld {
1004	# make sure we deliver these changes "synchronous" with the event loop.
1005	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1006	undef $CHLD_DELAY_W;
1007	&_child_wait;
1008	});
1009	}	1198	}
1010		1199
1011	sub child {	1200	sub child {
1012	my (undef, %arg) = @_;	1201	my (undef, %arg) = @_;
1013		1202
1014	defined (my $pid = $arg{pid} + 0)	1203	defined (my $pid = $arg{pid} + 0)
1015	or Carp::croak "required option 'pid' is missing";	1204	or Carp::croak "required option 'pid' is missing";
1016		1205
1017	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1018		1207
1019	unless ($WNOHANG) {
1020	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1208	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1021	}
1022		1209
1023	unless ($CHLD_W) {	1210	unless ($CHLD_W) {
1024	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1025	# child could be a zombie already, so make at least one round	1212	# child could be a zombie already, so make at least one round
1026	&_sigchld;	1213	&_sigchld;
1027	}	1214	}
1028		1215
1029	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1030	}	1217	}
1031		1218
1032	sub AnyEvent::Base::Child::DESTROY {	1219	sub AnyEvent::Base::child::DESTROY {
1033	my ($pid, $cb) = @{$_[0]};	1220	my ($pid, $cb) = @{$_[0]};
1034		1221
1035	delete $PID_CB{$pid}{$cb};	1222	delete $PID_CB{$pid}{$cb};
1036	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1037		1224
1038	undef $CHLD_W unless keys %PID_CB;	1225	undef $CHLD_W unless keys %PID_CB;
		1226	}
		1227
		1228	# idle emulation is done by simply using a timer, regardless
		1229	# of whether the process is idle or not, and not letting
		1230	# the callback use more than 50% of the time.
		1231	sub idle {
		1232	my (undef, %arg) = @_;
		1233
		1234	my ($cb, $w, $rcb) = $arg{cb};
		1235
		1236	$rcb = sub {
		1237	if ($cb) {
		1238	$w = _time;
		1239	&$cb;
		1240	$w = _time - $w;
		1241
		1242	# never use more then 50% of the time for the idle watcher,
		1243	# within some limits
		1244	$w = 0.0001 if $w < 0.0001;
		1245	$w = 5 if $w > 5;
		1246
		1247	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1248	} else {
		1249	# clean up...
		1250	undef $w;
		1251	undef $rcb;
		1252	}
		1253	};
		1254
		1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1256
		1257	bless \\$cb, "AnyEvent::Base::idle"
		1258	}
		1259
		1260	sub AnyEvent::Base::idle::DESTROY {
		1261	undef $${$_[0]};
1039	}	1262	}
1040		1263
1041	package AnyEvent::CondVar;	1264	package AnyEvent::CondVar;
1042		1265
1043	our @ISA = AnyEvent::CondVar::Base::;	1266	our @ISA = AnyEvent::CondVar::Base::;
…		…
1095	}	1318	}
1096		1319
1097	# undocumented/compatibility with pre-3.4	1320	# undocumented/compatibility with pre-3.4
1098	*broadcast = \&send;	1321	*broadcast = \&send;
1099	*wait = \&_wait;	1322	*wait = \&_wait;
		1323
		1324	=head1 ERROR AND EXCEPTION HANDLING
		1325
		1326	In general, AnyEvent does not do any error handling - it relies on the
		1327	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1328	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1329	checking of all AnyEvent methods, however, which is highly useful during
		1330	development.
		1331
		1332	As for exception handling (i.e. runtime errors and exceptions thrown while
		1333	executing a callback), this is not only highly event-loop specific, but
		1334	also not in any way wrapped by this module, as this is the job of the main
		1335	program.
		1336
		1337	The pure perl event loop simply re-throws the exception (usually
		1338	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1340	so on.
		1341
		1342	=head1 ENVIRONMENT VARIABLES
		1343
		1344	The following environment variables are used by this module or its
		1345	submodules.
		1346
		1347	Note that AnyEvent will remove I<all> environment variables starting with
		1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1349	enabled.
		1350
		1351	=over 4
		1352
		1353	=item C<PERL_ANYEVENT_VERBOSE>
		1354
		1355	By default, AnyEvent will be completely silent except in fatal
		1356	conditions. You can set this environment variable to make AnyEvent more
		1357	talkative.
		1358
		1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1360	conditions, such as not being able to load the event model specified by
		1361	C<PERL_ANYEVENT_MODEL>.
		1362
		1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1364	model it chooses.
		1365
		1366	=item C<PERL_ANYEVENT_STRICT>
		1367
		1368	AnyEvent does not do much argument checking by default, as thorough
		1369	argument checking is very costly. Setting this variable to a true value
		1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1371	check the arguments passed to most method calls. If it finds any problems
		1372	it will croak.
		1373
		1374	In other words, enables "strict" mode.
		1375
		1376	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1378	developing programs can be very useful, however.
		1379
		1380	=item C<PERL_ANYEVENT_MODEL>
		1381
		1382	This can be used to specify the event model to be used by AnyEvent, before
		1383	auto detection and -probing kicks in. It must be a string consisting
		1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1385	and the resulting module name is loaded and if the load was successful,
		1386	used as event model. If it fails to load AnyEvent will proceed with
		1387	auto detection and -probing.
		1388
		1389	This functionality might change in future versions.
		1390
		1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1392	could start your program like this:
		1393
		1394	PERL_ANYEVENT_MODEL=Perl perl ...
		1395
		1396	=item C<PERL_ANYEVENT_PROTOCOLS>
		1397
		1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1400	of auto probing).
		1401
		1402	Must be set to a comma-separated list of protocols or address families,
		1403	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1404	used, and preference will be given to protocols mentioned earlier in the
		1405	list.
		1406
		1407	This variable can effectively be used for denial-of-service attacks
		1408	against local programs (e.g. when setuid), although the impact is likely
		1409	small, as the program has to handle conenction and other failures anyways.
		1410
		1411	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1413	- only support IPv4, never try to resolve or contact IPv6
		1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1415	IPv6, but prefer IPv6 over IPv4.
		1416
		1417	=item C<PERL_ANYEVENT_EDNS0>
		1418
		1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1420	for DNS. This extension is generally useful to reduce DNS traffic, but
		1421	some (broken) firewalls drop such DNS packets, which is why it is off by
		1422	default.
		1423
		1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1425	EDNS0 in its DNS requests.
		1426
		1427	=item C<PERL_ANYEVENT_MAX_FORKS>
		1428
		1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1430	will create in parallel.
		1431
		1432	=back
1100		1433
1101	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1102		1435
1103	This is an advanced topic that you do not normally need to use AnyEvent in	1436	This is an advanced topic that you do not normally need to use AnyEvent in
1104	a module. This section is only of use to event loop authors who want to	1437	a module. This section is only of use to event loop authors who want to
…		…
1138		1471
1139	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1472	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1140	condition variables: code blocking while waiting for a condition will	1473	condition variables: code blocking while waiting for a condition will
1141	C<die>. This still works with most modules/usages, and blocking calls must	1474	C<die>. This still works with most modules/usages, and blocking calls must
1142	not be done in an interactive application, so it makes sense.	1475	not be done in an interactive application, so it makes sense.
1143
1144	=head1 ENVIRONMENT VARIABLES
1145
1146	The following environment variables are used by this module:
1147
1148	=over 4
1149
1150	=item C<PERL_ANYEVENT_VERBOSE>
1151
1152	By default, AnyEvent will be completely silent except in fatal
1153	conditions. You can set this environment variable to make AnyEvent more
1154	talkative.
1155
1156	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1157	conditions, such as not being able to load the event model specified by
1158	C<PERL_ANYEVENT_MODEL>.
1159
1160	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1161	model it chooses.
1162
1163	=item C<PERL_ANYEVENT_MODEL>
1164
1165	This can be used to specify the event model to be used by AnyEvent, before
1166	auto detection and -probing kicks in. It must be a string consisting
1167	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1168	and the resulting module name is loaded and if the load was successful,
1169	used as event model. If it fails to load AnyEvent will proceed with
1170	auto detection and -probing.
1171
1172	This functionality might change in future versions.
1173
1174	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1175	could start your program like this:
1176
1177	PERL_ANYEVENT_MODEL=Perl perl ...
1178
1179	=item C<PERL_ANYEVENT_PROTOCOLS>
1180
1181	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1182	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1183	of auto probing).
1184
1185	Must be set to a comma-separated list of protocols or address families,
1186	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1187	used, and preference will be given to protocols mentioned earlier in the
1188	list.
1189
1190	This variable can effectively be used for denial-of-service attacks
1191	against local programs (e.g. when setuid), although the impact is likely
1192	small, as the program has to handle connection errors already-
1193
1194	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1195	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1196	- only support IPv4, never try to resolve or contact IPv6
1197	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1198	IPv6, but prefer IPv6 over IPv4.
1199
1200	=item C<PERL_ANYEVENT_EDNS0>
1201
1202	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1203	for DNS. This extension is generally useful to reduce DNS traffic, but
1204	some (broken) firewalls drop such DNS packets, which is why it is off by
1205	default.
1206
1207	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1208	EDNS0 in its DNS requests.
1209
1210	=item C<PERL_ANYEVENT_MAX_FORKS>
1211
1212	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1213	will create in parallel.
1214
1215	=back
1216		1476
1217	=head1 EXAMPLE PROGRAM	1477	=head1 EXAMPLE PROGRAM
1218		1478
1219	The following program uses an I/O watcher to read data from STDIN, a timer	1479	The following program uses an I/O watcher to read data from STDIN, a timer
1220	to display a message once per second, and a condition variable to quit the	1480	to display a message once per second, and a condition variable to quit the
…		…
1414	watcher.	1674	watcher.
1415		1675
1416	=head3 Results	1676	=head3 Results
1417		1677
1418	name watchers bytes create invoke destroy comment	1678	name watchers bytes create invoke destroy comment
1419	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1420	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1421	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1422	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1423	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1424	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1425	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1426	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1427	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1428	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1429		1689
1430	=head3 Discussion	1690	=head3 Discussion
1431		1691
1432	The benchmark does I<not> measure scalability of the event loop very	1692	The benchmark does I<not> measure scalability of the event loop very
1433	well. For example, a select-based event loop (such as the pure perl one)	1693	well. For example, a select-based event loop (such as the pure perl one)
…		…
1634	=item * C-based event loops perform very well with small number of	1894	=item * C-based event loops perform very well with small number of
1635	watchers, as the management overhead dominates.	1895	watchers, as the management overhead dominates.
1636		1896
1637	=back	1897	=back
1638		1898
		1899	=head2 THE IO::Lambda BENCHMARK
		1900
		1901	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1904	shouldn't come as a surprise to anybody). As such, the benchmark is
		1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very
		1906	optimal. But how would AnyEvent compare when used without the extra
		1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1908
		1909	The benchmark itself creates an echo-server, and then, for 500 times,
		1910	connects to the echo server, sends a line, waits for the reply, and then
		1911	creates the next connection. This is a rather bad benchmark, as it doesn't
		1912	test the efficiency of the framework, but it is a benchmark nevertheless.
		1913
		1914	name runtime
		1915	Lambda/select 0.330 sec
		1916	+ optimized 0.122 sec
		1917	Lambda/AnyEvent 0.327 sec
		1918	+ optimized 0.138 sec
		1919	Raw sockets/select 0.077 sec
		1920	POE/select, components 0.662 sec
		1921	POE/select, raw sockets 0.226 sec
		1922	POE/select, optimized 0.404 sec
		1923
		1924	AnyEvent/select/nb 0.085 sec
		1925	AnyEvent/EV/nb 0.068 sec
		1926	+state machine 0.134 sec
		1927
		1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda
		1929	benchmarks actually make blocking connects and use 100% blocking I/O,
		1930	defeating the purpose of an event-based solution. All of the newly
		1931	written AnyEvent benchmarks use 100% non-blocking connects (using
		1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects
		1934	generally require a lot more bookkeeping and event handling than blocking
		1935	connects (which involve a single syscall only).
		1936
		1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1938	offers similar expressive power as POE and IO::Lambda (using conventional
		1939	Perl syntax), which means both the echo server and the client are 100%
		1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.
		1941
		1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets
		1943	benchmark", while AnyEvent + its pure perl backend easily beats
		1944	IO::Lambda and POE.
		1945
		1946	And even the 100% non-blocking version written using the high-level (and
		1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,
		1948	even thought it does all of DNS, tcp-connect and socket I/O in a
		1949	non-blocking way.
		1950
		1951	The two AnyEvent benchmarks can be found as F<eg/ae0.pl> and F<eg/ae2.pl>
		1952	in the AnyEvent distribution, the remaining benchmarks are part of the
		1953	IO::lambda distribution and were used without any changes.
		1954
		1955
		1956	=head1 SIGNALS
		1957
		1958	AnyEvent currently installs handlers for these signals:
		1959
		1960	=over 4
		1961
		1962	=item SIGCHLD
		1963
		1964	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1965	emulation for event loops that do not support them natively. Also, some
		1966	event loops install a similar handler.
		1967
		1968	=item SIGPIPE
		1969
		1970	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1971	when AnyEvent gets loaded.
		1972
		1973	The rationale for this is that AnyEvent users usually do not really depend
		1974	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1975	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1976	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1977	some random socket.
		1978
		1979	The rationale for installing a no-op handler as opposed to ignoring it is
		1980	that this way, the handler will be restored to defaults on exec.
		1981
		1982	Feel free to install your own handler, or reset it to defaults.
		1983
		1984	=back
		1985
		1986	=cut
		1987
		1988	$SIG{PIPE} = sub { }
		1989	unless defined $SIG{PIPE};
		1990
1639		1991
1640	=head1 FORK	1992	=head1 FORK
1641		1993
1642	Most event libraries are not fork-safe. The ones who are usually are	1994	Most event libraries are not fork-safe. The ones who are usually are
1643	because they rely on inefficient but fork-safe C<select> or C<poll>	1995	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1657	specified in the variable.	2009	specified in the variable.
1658		2010
1659	You can make AnyEvent completely ignore this variable by deleting it	2011	You can make AnyEvent completely ignore this variable by deleting it
1660	before the first watcher gets created, e.g. with a C<BEGIN> block:	2012	before the first watcher gets created, e.g. with a C<BEGIN> block:
1661		2013
1662	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2014	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1663		2015
1664	use AnyEvent;	2016	use AnyEvent;
1665		2017
1666	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2018	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1667	be used to probe what backend is used and gain other information (which is	2019	be used to probe what backend is used and gain other information (which is
1668	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2020	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2021	$ENV{PERL_ANYEVENT_STRICT}.
		2022
		2023
		2024	=head1 BUGS
		2025
		2026	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2027	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2028	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2029	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2030	pronounced).
1669		2031
1670		2032
1671	=head1 SEE ALSO	2033	=head1 SEE ALSO
1672		2034
1673	Utility functions: L<AnyEvent::Util>.	2035	Utility functions: L<AnyEvent::Util>.
…		…
1690	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2052	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1691		2053
1692		2054
1693	=head1 AUTHOR	2055	=head1 AUTHOR
1694		2056
1695	Marc Lehmann <schmorp@schmorp.de>	2057	Marc Lehmann <schmorp@schmorp.de>
1696	http://home.schmorp.de/	2058	http://home.schmorp.de/
1697		2059
1698	=cut	2060	=cut
1699		2061
1700	1	2062	1
1701		2063

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.148 by root, Sat May 31 00:40:16 2008 UTC vs. Revision 1.216 by root, Tue Jun 23 12:21:34 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.148 by root, Sat May 31 00:40:16 2008 UTC vs.
Revision 1.216 by root, Tue Jun 23 12:21:34 2009 UTC