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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.145 by root, Thu May 29 03:45:37 2008 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 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 });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	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
32	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
33	pragmatic way. For event models and certain classes of immortals alike,	56	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,	57	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	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	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
39	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
40	religion, a way of living, and most importantly: without forcing your	64	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	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	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
45	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
46	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
47	cannot use anything else, as it is simply incompatible to everything that	71	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	72	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.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	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
53	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
54	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,
55	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
56	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
57	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
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	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
61	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
62	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
63	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
121	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	148	is in control).
125		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
126	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
127	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
128	to it).	158	to it).
129		159
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		164
135	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
136		166
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
139	undef $w;	169	undef $w;
140	});	170	});
141		171
142	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,
143	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
144	declared.	174	declared.
145		175
146	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
147		177
148	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
149	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
150		180
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
154	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.
155	becomes ready.
156		192
157	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
160		196
…		…
164		200
165	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
166	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
167	handles.	203	handles.
168		204
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	210	warn "read: $input\n";
175	undef $w;	211	undef $w;
176	});	212	});
…		…
186		222
187	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
190		226
191	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
192	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
193	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.
194		232
195	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.
196		236
197	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	240	warn "timeout\n";
200	});	241	});
201		242
202	# to cancel the timer:	243	# to cancel the timer:
203	undef $w;	244	undef $w;
204		245
205	Example 2:
206
207	# 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.
208	my $w;
209		247
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
213	};	250	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		251
218	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
219		253
220	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
221	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
…		…
294	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
295	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
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	331	account.
298		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
299	=back	348	=back
300		349
301	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
302		351
303	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
304	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
305	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
306		355
307	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
310		359
…		…
326	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
327		376
328	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.
329		378
330	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
331	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
332	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
333	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
334	and exit status (as returned by waitpid), so unlike other watcher types,	383
335	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).
336		392
337	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
338	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
339	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
340		396
341	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
342	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
343	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
344		403
345	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
346	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
347	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
348		408
349	Example: fork a process and wait for it	409	Example: fork a process and wait for it
350		410
351	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
352		412
353	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
354		414
355	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
356	pid => $pid,	416	pid => $pid,
357	cb => sub {	417	cb => sub {
358	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
360	$done->send;	420	$done->send;
361	},	421	},
362	);	422	);
363		423
364	# do something else, then wait for process exit	424	# do something else, then wait for process exit
365	$done->recv;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w \|\|= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
366		461
367	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
368		463
369	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
370	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
…		…
376	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
377	because they represent a condition that must become true.	472	because they represent a condition that must become true.
378		473
379	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
381	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
382	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
383		480
384	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
385	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
386	were a callback, read about the caveats in the description for the C<<	483	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	484	->send >> method).
…		…
443		540
444	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$done->recv;	543	$done->recv;
447		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
448	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
449		563
450	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
451	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
452	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
585	=item $bool = $cv->ready	699	=item $bool = $cv->ready
586		700
587	Returns true when the condition is "true", i.e. whether C<send> or	701	Returns true when the condition is "true", i.e. whether C<send> or
588	C<croak> have been called.	702	C<croak> have been called.
589		703
590	=item $cb = $cv->cb ([new callback])	704	=item $cb = $cv->cb ($cb->($cv))
591		705
592	This is a mutator function that returns the callback set and optionally	706	This is a mutator function that returns the callback set and optionally
593	replaces it before doing so.	707	replaces it before doing so.
594		708
595	The callback will be called when the condition becomes "true", i.e. when	709	The callback will be called when the condition becomes "true", i.e. when
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	710	C<send> or C<croak> are called, with the only argument being the condition
597	or at any later time is guaranteed not to block.	711	variable itself. Calling C<recv> inside the callback or at any later time
		712	is guaranteed not to block.
598		713
599	=back	714	=back
600		715
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	716	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		717
…		…
619	AnyEvent::Impl::Tk based on Tk, very bad choice.	734	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	735	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	736	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.	737	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623		738
		739	# warning, support for IO::Async is only partial, as it is too broken
		740	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		741	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		742
624	There is no support for WxWidgets, as WxWidgets has no support for	743	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the	744	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	745	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for	746	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	747	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
731	=item L<AnyEvent::Util>	850	=item L<AnyEvent::Util>
732		851
733	Contains various utility functions that replace often-used but blocking	852	Contains various utility functions that replace often-used but blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	853	functions such as C<inet_aton> by event-/callback-based versions.
735		854
736	=item L<AnyEvent::Handle>
737
738	Provide read and write buffers and manages watchers for reads and writes.
739
740	=item L<AnyEvent::Socket>	855	=item L<AnyEvent::Socket>
741		856
742	Provides various utility functions for (internet protocol) sockets,	857	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	858	addresses and name resolution. Also functions to create non-blocking tcp
744	connections or tcp servers, with IPv6 and SRV record support and more.	859	connections or tcp servers, with IPv6 and SRV record support and more.
745		860
		861	=item L<AnyEvent::Handle>
		862
		863	Provide read and write buffers, manages watchers for reads and writes,
		864	supports raw and formatted I/O, I/O queued and fully transparent and
		865	non-blocking SSL/TLS.
		866
746	=item L<AnyEvent::DNS>	867	=item L<AnyEvent::DNS>
747		868
748	Provides rich asynchronous DNS resolver capabilities.	869	Provides rich asynchronous DNS resolver capabilities.
749		870
		871	=item L<AnyEvent::HTTP>
		872
		873	A simple-to-use HTTP library that is capable of making a lot of concurrent
		874	HTTP requests.
		875
750	=item L<AnyEvent::HTTPD>	876	=item L<AnyEvent::HTTPD>
751		877
752	Provides a simple web application server framework.	878	Provides a simple web application server framework.
753		879
754	=item L<AnyEvent::FastPing>	880	=item L<AnyEvent::FastPing>
755		881
756	The fastest ping in the west.	882	The fastest ping in the west.
757		883
		884	=item L<AnyEvent::DBI>
		885
		886	Executes L<DBI> requests asynchronously in a proxy process.
		887
		888	=item L<AnyEvent::AIO>
		889
		890	Truly asynchronous I/O, should be in the toolbox of every event
		891	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		892	together.
		893
		894	=item L<AnyEvent::BDB>
		895
		896	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		897	L<BDB> and AnyEvent together.
		898
		899	=item L<AnyEvent::GPSD>
		900
		901	A non-blocking interface to gpsd, a daemon delivering GPS information.
		902
		903	=item L<AnyEvent::IGS>
		904
		905	A non-blocking interface to the Internet Go Server protocol (used by
		906	L<App::IGS>).
		907
758	=item L<Net::IRC3>	908	=item L<AnyEvent::IRC>
759		909
760	AnyEvent based IRC client module family.	910	AnyEvent based IRC client module family (replacing the older Net::IRC3).
761		911
762	=item L<Net::XMPP2>	912	=item L<Net::XMPP2>
763		913
764	AnyEvent based XMPP (Jabber protocol) module family.	914	AnyEvent based XMPP (Jabber protocol) module family.
765		915
…		…
774		924
775	=item L<Coro>	925	=item L<Coro>
776		926
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	927	Has special support for AnyEvent via L<Coro::AnyEvent>.
778		928
779	=item L<AnyEvent::AIO>, L<IO::AIO>
780
781	Truly asynchronous I/O, should be in the toolbox of every event
782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
783	together.
784
785	=item L<AnyEvent::BDB>, L<BDB>
786
787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
788	IO::AIO and AnyEvent together.
789
790	=item L<IO::Lambda>	929	=item L<IO::Lambda>
791		930
792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	931	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793		932
794	=back	933	=back
…		…
796	=cut	935	=cut
797		936
798	package AnyEvent;	937	package AnyEvent;
799		938
800	no warnings;	939	no warnings;
801	use strict;	940	use strict qw(vars subs);
802		941
803	use Carp;	942	use Carp;
804		943
805	our $VERSION = '4.1';	944	our $VERSION = 4.412;
806	our $MODEL;	945	our $MODEL;
807		946
808	our $AUTOLOAD;	947	our $AUTOLOAD;
809	our @ISA;	948	our @ISA;
810		949
811	our @REGISTRY;	950	our @REGISTRY;
812		951
813	our $WIN32;	952	our $WIN32;
814		953
815	BEGIN {	954	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	955	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
817	eval "sub WIN32(){ $win32 }";	956	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		957
		958	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		959	if ${^TAINT};
818	}	960	}
819		961
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	962	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
821		963
822	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	964	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	982	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	983	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	984	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	985	[Wx:: => AnyEvent::Impl::POE::],
844	[Prima:: => AnyEvent::Impl::POE::],	986	[Prima:: => AnyEvent::Impl::POE::],
		987	# IO::Async is just too broken - we would need workaorunds for its
		988	# byzantine signal and broken child handling, among others.
		989	# IO::Async is rather hard to detect, as it doesn't have any
		990	# obvious default class.
		991	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		992	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		993	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
845	);	994	);
846		995
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	996	our %method = map +($_ => 1),
		997	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
848		998
849	our @post_detect;	999	our @post_detect;
850		1000
851	sub post_detect(&) {	1001	sub post_detect(&) {
852	my ($cb) = @_;	1002	my ($cb) = @_;
…		…
857	1	1007	1
858	} else {	1008	} else {
859	push @post_detect, $cb;	1009	push @post_detect, $cb;
860		1010
861	defined wantarray	1011	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"	1012	? bless \$cb, "AnyEvent::Util::postdetect"
863	: ()	1013	: ()
864	}	1014	}
865	}	1015	}
866		1016
867	sub AnyEvent::Util::PostDetect::DESTROY {	1017	sub AnyEvent::Util::postdetect::DESTROY {
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1018	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}	1019	}
870		1020
871	sub detect() {	1021	sub detect() {
872	unless ($MODEL) {	1022	unless ($MODEL) {
…		…
909	last;	1059	last;
910	}	1060	}
911	}	1061	}
912		1062
913	$MODEL	1063	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1064	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
915	}	1065	}
916	}	1066	}
917		1067
		1068	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1069
918	unshift @ISA, $MODEL;	1070	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1071
		1072	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
920		1073
921	(shift @post_detect)->() while @post_detect;	1074	(shift @post_detect)->() while @post_detect;
922	}	1075	}
923		1076
924	$MODEL	1077	$MODEL
…		…
934		1087
935	my $class = shift;	1088	my $class = shift;
936	$class->$func (@_);	1089	$class->$func (@_);
937	}	1090	}
938		1091
		1092	# utility function to dup a filehandle. this is used by many backends
		1093	# to support binding more than one watcher per filehandle (they usually
		1094	# allow only one watcher per fd, so we dup it to get a different one).
		1095	sub _dupfh($$;$$) {
		1096	my ($poll, $fh, $r, $w) = @_;
		1097
		1098	# cygwin requires the fh mode to be matching, unix doesn't
		1099	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1100	: $poll eq "w" ? ($w, ">")
		1101	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1102
		1103	open my $fh2, "$mode&" . fileno $fh
		1104	or die "cannot dup() filehandle: $!,";
		1105
		1106	# we assume CLOEXEC is already set by perl in all important cases
		1107
		1108	($fh2, $rw)
		1109	}
		1110
939	package AnyEvent::Base;	1111	package AnyEvent::Base;
940		1112
941	# default implementation for now and time	1113	# default implementations for many methods
942		1114
943	use Time::HiRes ();	1115	BEGIN {
		1116	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1117	*_time = \&Time::HiRes::time;
		1118	# if (eval "use POSIX (); (POSIX::times())...
		1119	} else {
		1120	*_time = sub { time }; # epic fail
		1121	}
		1122	}
944		1123
945	sub time { Time::HiRes::time }	1124	sub time { _time }
946	sub now { Time::HiRes::time }	1125	sub now { _time }
		1126	sub now_update { }
947		1127
948	# default implementation for ->condvar	1128	# default implementation for ->condvar
949		1129
950	sub condvar {	1130	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1131	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
952	}	1132	}
953		1133
954	# default implementation for ->signal	1134	# default implementation for ->signal
955		1135
956	our %SIG_CB;	1136	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1137
		1138	sub _signal_exec {
		1139	sysread $SIGPIPE_R, my $dummy, 4;
		1140
		1141	while (%SIG_EV) {
		1142	for (keys %SIG_EV) {
		1143	delete $SIG_EV{$_};
		1144	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1145	}
		1146	}
		1147	}
957		1148
958	sub signal {	1149	sub signal {
959	my (undef, %arg) = @_;	1150	my (undef, %arg) = @_;
960		1151
		1152	unless ($SIGPIPE_R) {
		1153	require Fcntl;
		1154
		1155	if (AnyEvent::WIN32) {
		1156	require AnyEvent::Util;
		1157
		1158	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1159	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1160	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1161	} else {
		1162	pipe $SIGPIPE_R, $SIGPIPE_W;
		1163	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1164	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1165
		1166	# not strictly required, as $^F is normally 2, but let's make sure...
		1167	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1168	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1169	}
		1170
		1171	$SIGPIPE_R
		1172	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1173
		1174	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1175	}
		1176
961	my $signal = uc $arg{signal}	1177	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";	1178	or Carp::croak "required option 'signal' is missing";
963		1179
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1180	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
965	$SIG{$signal} \|\|= sub {	1181	$SIG{$signal} \|\|= sub {
966	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1182	local $!;
		1183	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1184	undef $SIG_EV{$signal};
967	};	1185	};
968		1186
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1187	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
970	}	1188	}
971		1189
972	sub AnyEvent::Base::Signal::DESTROY {	1190	sub AnyEvent::Base::signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};	1191	my ($signal, $cb) = @{$_[0]};
974		1192
975	delete $SIG_CB{$signal}{$cb};	1193	delete $SIG_CB{$signal}{$cb};
976		1194
		1195	# delete doesn't work with older perls - they then
		1196	# print weird messages, or just unconditionally exit
		1197	# instead of getting the default action.
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1198	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
978	}	1199	}
979		1200
980	# default implementation for ->child	1201	# default implementation for ->child
981		1202
982	our %PID_CB;	1203	our %PID_CB;
983	our $CHLD_W;	1204	our $CHLD_W;
984	our $CHLD_DELAY_W;	1205	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;	1206	our $WNOHANG;
987		1207
988	sub _child_wait {	1208	sub _sigchld {
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1209	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1210	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
991	(values %{ $PID_CB{0} \|\| {} });	1211	(values %{ $PID_CB{0} \|\| {} });
992	}	1212	}
993
994	undef $PID_IDLE;
995	}
996
997	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.
999	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1000	undef $CHLD_DELAY_W;
1001	&_child_wait;
1002	});
1003	}	1213	}
1004		1214
1005	sub child {	1215	sub child {
1006	my (undef, %arg) = @_;	1216	my (undef, %arg) = @_;
1007		1217
1008	defined (my $pid = $arg{pid} + 0)	1218	defined (my $pid = $arg{pid} + 0)
1009	or Carp::croak "required option 'pid' is missing";	1219	or Carp::croak "required option 'pid' is missing";
1010		1220
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1221	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1012		1222
1013	unless ($WNOHANG) {
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1223	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1015	}
1016		1224
1017	unless ($CHLD_W) {	1225	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1226	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1019	# child could be a zombie already, so make at least one round	1227	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1228	&_sigchld;
1021	}	1229	}
1022		1230
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1231	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1024	}	1232	}
1025		1233
1026	sub AnyEvent::Base::Child::DESTROY {	1234	sub AnyEvent::Base::child::DESTROY {
1027	my ($pid, $cb) = @{$_[0]};	1235	my ($pid, $cb) = @{$_[0]};
1028		1236
1029	delete $PID_CB{$pid}{$cb};	1237	delete $PID_CB{$pid}{$cb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1238	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1239
1032	undef $CHLD_W unless keys %PID_CB;	1240	undef $CHLD_W unless keys %PID_CB;
		1241	}
		1242
		1243	# idle emulation is done by simply using a timer, regardless
		1244	# of whether the process is idle or not, and not letting
		1245	# the callback use more than 50% of the time.
		1246	sub idle {
		1247	my (undef, %arg) = @_;
		1248
		1249	my ($cb, $w, $rcb) = $arg{cb};
		1250
		1251	$rcb = sub {
		1252	if ($cb) {
		1253	$w = _time;
		1254	&$cb;
		1255	$w = _time - $w;
		1256
		1257	# never use more then 50% of the time for the idle watcher,
		1258	# within some limits
		1259	$w = 0.0001 if $w < 0.0001;
		1260	$w = 5 if $w > 5;
		1261
		1262	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1263	} else {
		1264	# clean up...
		1265	undef $w;
		1266	undef $rcb;
		1267	}
		1268	};
		1269
		1270	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1271
		1272	bless \\$cb, "AnyEvent::Base::idle"
		1273	}
		1274
		1275	sub AnyEvent::Base::idle::DESTROY {
		1276	undef $${$_[0]};
1033	}	1277	}
1034		1278
1035	package AnyEvent::CondVar;	1279	package AnyEvent::CondVar;
1036		1280
1037	our @ISA = AnyEvent::CondVar::Base::;	1281	our @ISA = AnyEvent::CondVar::Base::;
…		…
1089	}	1333	}
1090		1334
1091	# undocumented/compatibility with pre-3.4	1335	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	1336	*broadcast = \&send;
1093	*wait = \&_wait;	1337	*wait = \&_wait;
		1338
		1339	=head1 ERROR AND EXCEPTION HANDLING
		1340
		1341	In general, AnyEvent does not do any error handling - it relies on the
		1342	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1343	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1344	checking of all AnyEvent methods, however, which is highly useful during
		1345	development.
		1346
		1347	As for exception handling (i.e. runtime errors and exceptions thrown while
		1348	executing a callback), this is not only highly event-loop specific, but
		1349	also not in any way wrapped by this module, as this is the job of the main
		1350	program.
		1351
		1352	The pure perl event loop simply re-throws the exception (usually
		1353	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1354	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1355	so on.
		1356
		1357	=head1 ENVIRONMENT VARIABLES
		1358
		1359	The following environment variables are used by this module or its
		1360	submodules.
		1361
		1362	Note that AnyEvent will remove I<all> environment variables starting with
		1363	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1364	enabled.
		1365
		1366	=over 4
		1367
		1368	=item C<PERL_ANYEVENT_VERBOSE>
		1369
		1370	By default, AnyEvent will be completely silent except in fatal
		1371	conditions. You can set this environment variable to make AnyEvent more
		1372	talkative.
		1373
		1374	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1375	conditions, such as not being able to load the event model specified by
		1376	C<PERL_ANYEVENT_MODEL>.
		1377
		1378	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1379	model it chooses.
		1380
		1381	=item C<PERL_ANYEVENT_STRICT>
		1382
		1383	AnyEvent does not do much argument checking by default, as thorough
		1384	argument checking is very costly. Setting this variable to a true value
		1385	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1386	check the arguments passed to most method calls. If it finds any problems,
		1387	it will croak.
		1388
		1389	In other words, enables "strict" mode.
		1390
		1391	Unlike C<use strict>, it is definitely recommended to keep it off in
		1392	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1393	developing programs can be very useful, however.
		1394
		1395	=item C<PERL_ANYEVENT_MODEL>
		1396
		1397	This can be used to specify the event model to be used by AnyEvent, before
		1398	auto detection and -probing kicks in. It must be a string consisting
		1399	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1400	and the resulting module name is loaded and if the load was successful,
		1401	used as event model. If it fails to load AnyEvent will proceed with
		1402	auto detection and -probing.
		1403
		1404	This functionality might change in future versions.
		1405
		1406	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1407	could start your program like this:
		1408
		1409	PERL_ANYEVENT_MODEL=Perl perl ...
		1410
		1411	=item C<PERL_ANYEVENT_PROTOCOLS>
		1412
		1413	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1414	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1415	of auto probing).
		1416
		1417	Must be set to a comma-separated list of protocols or address families,
		1418	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1419	used, and preference will be given to protocols mentioned earlier in the
		1420	list.
		1421
		1422	This variable can effectively be used for denial-of-service attacks
		1423	against local programs (e.g. when setuid), although the impact is likely
		1424	small, as the program has to handle conenction and other failures anyways.
		1425
		1426	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1427	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1428	- only support IPv4, never try to resolve or contact IPv6
		1429	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1430	IPv6, but prefer IPv6 over IPv4.
		1431
		1432	=item C<PERL_ANYEVENT_EDNS0>
		1433
		1434	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1435	for DNS. This extension is generally useful to reduce DNS traffic, but
		1436	some (broken) firewalls drop such DNS packets, which is why it is off by
		1437	default.
		1438
		1439	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1440	EDNS0 in its DNS requests.
		1441
		1442	=item C<PERL_ANYEVENT_MAX_FORKS>
		1443
		1444	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1445	will create in parallel.
		1446
		1447	=back
1094		1448
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1449	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		1450
1097	This is an advanced topic that you do not normally need to use AnyEvent in	1451	This is an advanced topic that you do not normally need to use AnyEvent in
1098	a module. This section is only of use to event loop authors who want to	1452	a module. This section is only of use to event loop authors who want to
…		…
1132		1486
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1487	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	1488	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	1489	C<die>. This still works with most modules/usages, and blocking calls must
1136	not be done in an interactive application, so it makes sense.	1490	not be done in an interactive application, so it makes sense.
1137
1138	=head1 ENVIRONMENT VARIABLES
1139
1140	The following environment variables are used by this module:
1141
1142	=over 4
1143
1144	=item C<PERL_ANYEVENT_VERBOSE>
1145
1146	By default, AnyEvent will be completely silent except in fatal
1147	conditions. You can set this environment variable to make AnyEvent more
1148	talkative.
1149
1150	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151	conditions, such as not being able to load the event model specified by
1152	C<PERL_ANYEVENT_MODEL>.
1153
1154	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155	model it chooses.
1156
1157	=item C<PERL_ANYEVENT_MODEL>
1158
1159	This can be used to specify the event model to be used by AnyEvent, before
1160	auto detection and -probing kicks in. It must be a string consisting
1161	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162	and the resulting module name is loaded and if the load was successful,
1163	used as event model. If it fails to load AnyEvent will proceed with
1164	auto detection and -probing.
1165
1166	This functionality might change in future versions.
1167
1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169	could start your program like this:
1170
1171	PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173	=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177	of auto probing).
1178
1179	Must be set to a comma-separated list of protocols or address families,
1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181	used, and preference will be given to protocols mentioned earlier in the
1182	list.
1183
1184	This variable can effectively be used for denial-of-service attacks
1185	against local programs (e.g. when setuid), although the impact is likely
1186	small, as the program has to handle connection errors already-
1187
1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190	- only support IPv4, never try to resolve or contact IPv6
1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192	IPv6, but prefer IPv6 over IPv4.
1193
1194	=item C<PERL_ANYEVENT_EDNS0>
1195
1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197	for DNS. This extension is generally useful to reduce DNS traffic, but
1198	some (broken) firewalls drop such DNS packets, which is why it is off by
1199	default.
1200
1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202	EDNS0 in its DNS requests.
1203
1204	=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207	will create in parallel.
1208
1209	=back
1210		1491
1211	=head1 EXAMPLE PROGRAM	1492	=head1 EXAMPLE PROGRAM
1212		1493
1213	The following program uses an I/O watcher to read data from STDIN, a timer	1494	The following program uses an I/O watcher to read data from STDIN, a timer
1214	to display a message once per second, and a condition variable to quit the	1495	to display a message once per second, and a condition variable to quit the
…		…
1408	watcher.	1689	watcher.
1409		1690
1410	=head3 Results	1691	=head3 Results
1411		1692
1412	name watchers bytes create invoke destroy comment	1693	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1694	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1414	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1695	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1415	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1696	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1416	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1697	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1417	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1698	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1418	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1699	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1419	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1700	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1420	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1701	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1421	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1702	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1703	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1423		1704
1424	=head3 Discussion	1705	=head3 Discussion
1425		1706
1426	The benchmark does I<not> measure scalability of the event loop very	1707	The benchmark does I<not> measure scalability of the event loop very
1427	well. For example, a select-based event loop (such as the pure perl one)	1708	well. For example, a select-based event loop (such as the pure perl one)
…		…
1628	=item * C-based event loops perform very well with small number of	1909	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	1910	watchers, as the management overhead dominates.
1630		1911
1631	=back	1912	=back
1632		1913
		1914	=head2 THE IO::Lambda BENCHMARK
		1915
		1916	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1917	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1918	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1919	shouldn't come as a surprise to anybody). As such, the benchmark is
		1920	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1921	very optimal. But how would AnyEvent compare when used without the extra
		1922	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1923
		1924	The benchmark itself creates an echo-server, and then, for 500 times,
		1925	connects to the echo server, sends a line, waits for the reply, and then
		1926	creates the next connection. This is a rather bad benchmark, as it doesn't
		1927	test the efficiency of the framework or much non-blocking I/O, but it is a
		1928	benchmark nevertheless.
		1929
		1930	name runtime
		1931	Lambda/select 0.330 sec
		1932	+ optimized 0.122 sec
		1933	Lambda/AnyEvent 0.327 sec
		1934	+ optimized 0.138 sec
		1935	Raw sockets/select 0.077 sec
		1936	POE/select, components 0.662 sec
		1937	POE/select, raw sockets 0.226 sec
		1938	POE/select, optimized 0.404 sec
		1939
		1940	AnyEvent/select/nb 0.085 sec
		1941	AnyEvent/EV/nb 0.068 sec
		1942	+state machine 0.134 sec
		1943
		1944	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1945	benchmarks actually make blocking connects and use 100% blocking I/O,
		1946	defeating the purpose of an event-based solution. All of the newly
		1947	written AnyEvent benchmarks use 100% non-blocking connects (using
		1948	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1949	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		1950	generally require a lot more bookkeeping and event handling than blocking
		1951	connects (which involve a single syscall only).
		1952
		1953	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1954	offers similar expressive power as POE and IO::Lambda, using conventional
		1955	Perl syntax. This means that both the echo server and the client are 100%
		1956	non-blocking, further placing it at a disadvantage.
		1957
		1958	As you can see, the AnyEvent + EV combination even beats the
		1959	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1960	backend easily beats IO::Lambda and POE.
		1961
		1962	And even the 100% non-blocking version written using the high-level (and
		1963	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		1964	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1965	in a non-blocking way.
		1966
		1967	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		1968	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		1969	part of the IO::lambda distribution and were used without any changes.
		1970
		1971
		1972	=head1 SIGNALS
		1973
		1974	AnyEvent currently installs handlers for these signals:
		1975
		1976	=over 4
		1977
		1978	=item SIGCHLD
		1979
		1980	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1981	emulation for event loops that do not support them natively. Also, some
		1982	event loops install a similar handler.
		1983
		1984	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		1985	reset it to default, to avoid losing child exit statuses.
		1986
		1987	=item SIGPIPE
		1988
		1989	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1990	when AnyEvent gets loaded.
		1991
		1992	The rationale for this is that AnyEvent users usually do not really depend
		1993	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1994	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1995	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1996	some random socket.
		1997
		1998	The rationale for installing a no-op handler as opposed to ignoring it is
		1999	that this way, the handler will be restored to defaults on exec.
		2000
		2001	Feel free to install your own handler, or reset it to defaults.
		2002
		2003	=back
		2004
		2005	=cut
		2006
		2007	undef $SIG{CHLD}
		2008	if $SIG{CHLD} eq 'IGNORE';
		2009
		2010	$SIG{PIPE} = sub { }
		2011	unless defined $SIG{PIPE};
1633		2012
1634	=head1 FORK	2013	=head1 FORK
1635		2014
1636	Most event libraries are not fork-safe. The ones who are usually are	2015	Most event libraries are not fork-safe. The ones who are usually are
1637	because they rely on inefficient but fork-safe C<select> or C<poll>	2016	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1651	specified in the variable.	2030	specified in the variable.
1652		2031
1653	You can make AnyEvent completely ignore this variable by deleting it	2032	You can make AnyEvent completely ignore this variable by deleting it
1654	before the first watcher gets created, e.g. with a C<BEGIN> block:	2033	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2034
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2035	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2036
1658	use AnyEvent;	2037	use AnyEvent;
1659		2038
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2039	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661	be used to probe what backend is used and gain other information (which is	2040	be used to probe what backend is used and gain other information (which is
1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2041	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2042	$ENV{PERL_ANYEVENT_STRICT}.
		2043
		2044	Note that AnyEvent will remove I<all> environment variables starting with
		2045	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2046	enabled.
		2047
		2048
		2049	=head1 BUGS
		2050
		2051	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2052	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2053	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2054	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2055	pronounced).
1663		2056
1664		2057
1665	=head1 SEE ALSO	2058	=head1 SEE ALSO
1666		2059
1667	Utility functions: L<AnyEvent::Util>.	2060	Utility functions: L<AnyEvent::Util>.
…		…
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2077	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1685		2078
1686		2079
1687	=head1 AUTHOR	2080	=head1 AUTHOR
1688		2081
1689	Marc Lehmann <schmorp@schmorp.de>	2082	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	2083	http://home.schmorp.de/
1691		2084
1692	=cut	2085	=cut
1693		2086
1694	1	2087	1
1695		2088

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.145 by root, Thu May 29 03:45:37 2008 UTC vs. Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.145 by root, Thu May 29 03:45:37 2008 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC