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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.155 by root, Fri Jun 6 07:07:01 2008 UTC vs.
Revision 1.223 by root, Mon Jun 29 21:00:32 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.
…		…
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
347	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
348	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
349	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.
350		403
351	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
352	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
353	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>).
354		408
355	Example: fork a process and wait for it	409	Example: fork a process and wait for it
356		410
357	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
358		412
…		…
368	);	422	);
369		423
370	# do something else, then wait for process exit	424	# do something else, then wait for process exit
371	$done->recv;	425	$done->recv;
372		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	});
		461
373	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
374		463
375	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
376	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
377	will actively watch for new events and call your callbacks.	466	will actively watch for new events and call your callbacks.
…		…
382	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
383	because they represent a condition that must become true.	472	because they represent a condition that must become true.
384		473
385	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
387	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
388	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
389		480
390	After creation, the condition variable is "false" until it becomes "true"	481	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	482	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<<	483	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	484	->send >> method).
…		…
449		540
450	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	543	$done->recv;
453		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
454	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
455		563
456	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
457	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
458	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
…		…
491		599
492	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
493		601
494	=item $cv->end	602	=item $cv->end
495		603
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497
498	These two methods can be used to combine many transactions/events into	604	These two methods can be used to combine many transactions/events into
499	one. For example, a function that pings many hosts in parallel might want	605	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
501		607
502	Every call to C<< ->begin >> will increment a counter, and every call to	608	Every call to C<< ->begin >> will increment a counter, and every call to
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
504	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
505	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
506	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
507		613
508	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
509		645
510	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
511		647
512	my %result;	648	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
533	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
534	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
535	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	672	doesn't execute once).
537		673
538	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
540	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
541	C<begin> and for each subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
542		679
543	=back	680	=back
544		681
545	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
546		683
…		…
591	=item $bool = $cv->ready	728	=item $bool = $cv->ready
592		729
593	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	731	C<croak> have been called.
595		732
596	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
597		734
598	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	736	replaces it before doing so.
600		737
601	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
…		…
626	AnyEvent::Impl::Tk based on Tk, very bad choice.	763	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.	766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630		767
		768	# warning, support for IO::Async is only partial, as it is too broken
		769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		771
631	There is no support for WxWidgets, as WxWidgets has no support for	772	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the	773	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for	775	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
738	=item L<AnyEvent::Util>	879	=item L<AnyEvent::Util>
739		880
740	Contains various utility functions that replace often-used but blocking	881	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	882	functions such as C<inet_aton> by event-/callback-based versions.
742		883
743	=item L<AnyEvent::Handle>
744
745	Provide read and write buffers and manages watchers for reads and writes.
746
747	=item L<AnyEvent::Socket>	884	=item L<AnyEvent::Socket>
748		885
749	Provides various utility functions for (internet protocol) sockets,	886	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	887	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	888	connections or tcp servers, with IPv6 and SRV record support and more.
752		889
		890	=item L<AnyEvent::Handle>
		891
		892	Provide read and write buffers, manages watchers for reads and writes,
		893	supports raw and formatted I/O, I/O queued and fully transparent and
		894	non-blocking SSL/TLS.
		895
753	=item L<AnyEvent::DNS>	896	=item L<AnyEvent::DNS>
754		897
755	Provides rich asynchronous DNS resolver capabilities.	898	Provides rich asynchronous DNS resolver capabilities.
756		899
757	=item L<AnyEvent::HTTP>	900	=item L<AnyEvent::HTTP>
…		…
765		908
766	=item L<AnyEvent::FastPing>	909	=item L<AnyEvent::FastPing>
767		910
768	The fastest ping in the west.	911	The fastest ping in the west.
769		912
		913	=item L<AnyEvent::DBI>
		914
		915	Executes L<DBI> requests asynchronously in a proxy process.
		916
		917	=item L<AnyEvent::AIO>
		918
		919	Truly asynchronous I/O, should be in the toolbox of every event
		920	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		921	together.
		922
		923	=item L<AnyEvent::BDB>
		924
		925	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		926	L<BDB> and AnyEvent together.
		927
		928	=item L<AnyEvent::GPSD>
		929
		930	A non-blocking interface to gpsd, a daemon delivering GPS information.
		931
		932	=item L<AnyEvent::IGS>
		933
		934	A non-blocking interface to the Internet Go Server protocol (used by
		935	L<App::IGS>).
		936
770	=item L<Net::IRC3>	937	=item L<AnyEvent::IRC>
771		938
772	AnyEvent based IRC client module family.	939	AnyEvent based IRC client module family (replacing the older Net::IRC3).
773		940
774	=item L<Net::XMPP2>	941	=item L<Net::XMPP2>
775		942
776	AnyEvent based XMPP (Jabber protocol) module family.	943	AnyEvent based XMPP (Jabber protocol) module family.
777		944
…		…
786		953
787	=item L<Coro>	954	=item L<Coro>
788		955
789	Has special support for AnyEvent via L<Coro::AnyEvent>.	956	Has special support for AnyEvent via L<Coro::AnyEvent>.
790		957
791	=item L<AnyEvent::AIO>, L<IO::AIO>
792
793	Truly asynchronous I/O, should be in the toolbox of every event
794	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
795	together.
796
797	=item L<AnyEvent::BDB>, L<BDB>
798
799	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
800	IO::AIO and AnyEvent together.
801
802	=item L<IO::Lambda>	958	=item L<IO::Lambda>
803		959
804	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	960	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
805		961
806	=back	962	=back
…		…
808	=cut	964	=cut
809		965
810	package AnyEvent;	966	package AnyEvent;
811		967
812	no warnings;	968	no warnings;
813	use strict;	969	use strict qw(vars subs);
814		970
815	use Carp;	971	use Carp;
816		972
817	our $VERSION = 4.14;	973	our $VERSION = 4.45;
818	our $MODEL;	974	our $MODEL;
819		975
820	our $AUTOLOAD;	976	our $AUTOLOAD;
821	our @ISA;	977	our @ISA;
822		978
823	our @REGISTRY;	979	our @REGISTRY;
824		980
825	our $WIN32;	981	our $WIN32;
826		982
827	BEGIN {	983	BEGIN {
828	my $win32 = ! ! ($^O =~ /mswin32/i);	984	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
829	eval "sub WIN32(){ $win32 }";	985	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		986
		987	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		988	if ${^TAINT};
830	}	989	}
831		990
832	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	991	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
833		992
834	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	993	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
852	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1011	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
853	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1012	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
854	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1013	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
855	[Wx:: => AnyEvent::Impl::POE::],	1014	[Wx:: => AnyEvent::Impl::POE::],
856	[Prima:: => AnyEvent::Impl::POE::],	1015	[Prima:: => AnyEvent::Impl::POE::],
		1016	# IO::Async is just too broken - we would need workaorunds for its
		1017	# byzantine signal and broken child handling, among others.
		1018	# IO::Async is rather hard to detect, as it doesn't have any
		1019	# obvious default class.
		1020	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1021	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1022	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
857	);	1023	);
858		1024
859	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1025	our %method = map +($_ => 1),
		1026	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
860		1027
861	our @post_detect;	1028	our @post_detect;
862		1029
863	sub post_detect(&) {	1030	sub post_detect(&) {
864	my ($cb) = @_;	1031	my ($cb) = @_;
…		…
869	1	1036	1
870	} else {	1037	} else {
871	push @post_detect, $cb;	1038	push @post_detect, $cb;
872		1039
873	defined wantarray	1040	defined wantarray
874	? bless \$cb, "AnyEvent::Util::PostDetect"	1041	? bless \$cb, "AnyEvent::Util::postdetect"
875	: ()	1042	: ()
876	}	1043	}
877	}	1044	}
878		1045
879	sub AnyEvent::Util::PostDetect::DESTROY {	1046	sub AnyEvent::Util::postdetect::DESTROY {
880	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1047	@post_detect = grep $_ != ${$_[0]}, @post_detect;
881	}	1048	}
882		1049
883	sub detect() {	1050	sub detect() {
884	unless ($MODEL) {	1051	unless ($MODEL) {
…		…
921	last;	1088	last;
922	}	1089	}
923	}	1090	}
924		1091
925	$MODEL	1092	$MODEL
926	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1093	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
927	}	1094	}
928	}	1095	}
929		1096
		1097	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1098
930	unshift @ISA, $MODEL;	1099	unshift @ISA, $MODEL;
931	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1100
		1101	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
932		1102
933	(shift @post_detect)->() while @post_detect;	1103	(shift @post_detect)->() while @post_detect;
934	}	1104	}
935		1105
936	$MODEL	1106	$MODEL
…		…
946		1116
947	my $class = shift;	1117	my $class = shift;
948	$class->$func (@_);	1118	$class->$func (@_);
949	}	1119	}
950		1120
		1121	# utility function to dup a filehandle. this is used by many backends
		1122	# to support binding more than one watcher per filehandle (they usually
		1123	# allow only one watcher per fd, so we dup it to get a different one).
		1124	sub _dupfh($$;$$) {
		1125	my ($poll, $fh, $r, $w) = @_;
		1126
		1127	# cygwin requires the fh mode to be matching, unix doesn't
		1128	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1129	: $poll eq "w" ? ($w, ">")
		1130	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1131
		1132	open my $fh2, "$mode&" . fileno $fh
		1133	or die "cannot dup() filehandle: $!,";
		1134
		1135	# we assume CLOEXEC is already set by perl in all important cases
		1136
		1137	($fh2, $rw)
		1138	}
		1139
951	package AnyEvent::Base;	1140	package AnyEvent::Base;
952		1141
953	# default implementation for now and time	1142	# default implementations for many methods
954		1143
955	use Time::HiRes ();	1144	BEGIN {
		1145	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1146	*_time = \&Time::HiRes::time;
		1147	# if (eval "use POSIX (); (POSIX::times())...
		1148	} else {
		1149	*_time = sub { time }; # epic fail
		1150	}
		1151	}
956		1152
957	sub time { Time::HiRes::time }	1153	sub time { _time }
958	sub now { Time::HiRes::time }	1154	sub now { _time }
		1155	sub now_update { }
959		1156
960	# default implementation for ->condvar	1157	# default implementation for ->condvar
961		1158
962	sub condvar {	1159	sub condvar {
963	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1160	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
964	}	1161	}
965		1162
966	# default implementation for ->signal	1163	# default implementation for ->signal
967		1164
968	our %SIG_CB;	1165	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1166
		1167	sub _signal_exec {
		1168	sysread $SIGPIPE_R, my $dummy, 4;
		1169
		1170	while (%SIG_EV) {
		1171	for (keys %SIG_EV) {
		1172	delete $SIG_EV{$_};
		1173	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1174	}
		1175	}
		1176	}
969		1177
970	sub signal {	1178	sub signal {
971	my (undef, %arg) = @_;	1179	my (undef, %arg) = @_;
972		1180
		1181	unless ($SIGPIPE_R) {
		1182	require Fcntl;
		1183
		1184	if (AnyEvent::WIN32) {
		1185	require AnyEvent::Util;
		1186
		1187	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1188	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1189	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1190	} else {
		1191	pipe $SIGPIPE_R, $SIGPIPE_W;
		1192	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1193	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1194
		1195	# not strictly required, as $^F is normally 2, but let's make sure...
		1196	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1197	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1198	}
		1199
		1200	$SIGPIPE_R
		1201	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1202
		1203	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1204	}
		1205
973	my $signal = uc $arg{signal}	1206	my $signal = uc $arg{signal}
974	or Carp::croak "required option 'signal' is missing";	1207	or Carp::croak "required option 'signal' is missing";
975		1208
976	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1209	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
977	$SIG{$signal} \|\|= sub {	1210	$SIG{$signal} \|\|= sub {
978	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1211	local $!;
		1212	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1213	undef $SIG_EV{$signal};
979	};	1214	};
980		1215
981	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1216	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
982	}	1217	}
983		1218
984	sub AnyEvent::Base::Signal::DESTROY {	1219	sub AnyEvent::Base::signal::DESTROY {
985	my ($signal, $cb) = @{$_[0]};	1220	my ($signal, $cb) = @{$_[0]};
986		1221
987	delete $SIG_CB{$signal}{$cb};	1222	delete $SIG_CB{$signal}{$cb};
988		1223
		1224	# delete doesn't work with older perls - they then
		1225	# print weird messages, or just unconditionally exit
		1226	# instead of getting the default action.
989	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1227	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
990	}	1228	}
991		1229
992	# default implementation for ->child	1230	# default implementation for ->child
993		1231
994	our %PID_CB;	1232	our %PID_CB;
995	our $CHLD_W;	1233	our $CHLD_W;
996	our $CHLD_DELAY_W;	1234	our $CHLD_DELAY_W;
997	our $PID_IDLE;
998	our $WNOHANG;	1235	our $WNOHANG;
999		1236
1000	sub _child_wait {	1237	sub _sigchld {
1001	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1238	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1002	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1239	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
1003	(values %{ $PID_CB{0} \|\| {} });	1240	(values %{ $PID_CB{0} \|\| {} });
1004	}	1241	}
1005
1006	undef $PID_IDLE;
1007	}
1008
1009	sub _sigchld {
1010	# make sure we deliver these changes "synchronous" with the event loop.
1011	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1012	undef $CHLD_DELAY_W;
1013	&_child_wait;
1014	});
1015	}	1242	}
1016		1243
1017	sub child {	1244	sub child {
1018	my (undef, %arg) = @_;	1245	my (undef, %arg) = @_;
1019		1246
1020	defined (my $pid = $arg{pid} + 0)	1247	defined (my $pid = $arg{pid} + 0)
1021	or Carp::croak "required option 'pid' is missing";	1248	or Carp::croak "required option 'pid' is missing";
1022		1249
1023	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1250	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1024		1251
1025	unless ($WNOHANG) {
1026	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1252	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1027	}
1028		1253
1029	unless ($CHLD_W) {	1254	unless ($CHLD_W) {
1030	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1255	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1031	# child could be a zombie already, so make at least one round	1256	# child could be a zombie already, so make at least one round
1032	&_sigchld;	1257	&_sigchld;
1033	}	1258	}
1034		1259
1035	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1260	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1036	}	1261	}
1037		1262
1038	sub AnyEvent::Base::Child::DESTROY {	1263	sub AnyEvent::Base::child::DESTROY {
1039	my ($pid, $cb) = @{$_[0]};	1264	my ($pid, $cb) = @{$_[0]};
1040		1265
1041	delete $PID_CB{$pid}{$cb};	1266	delete $PID_CB{$pid}{$cb};
1042	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1267	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1043		1268
1044	undef $CHLD_W unless keys %PID_CB;	1269	undef $CHLD_W unless keys %PID_CB;
		1270	}
		1271
		1272	# idle emulation is done by simply using a timer, regardless
		1273	# of whether the process is idle or not, and not letting
		1274	# the callback use more than 50% of the time.
		1275	sub idle {
		1276	my (undef, %arg) = @_;
		1277
		1278	my ($cb, $w, $rcb) = $arg{cb};
		1279
		1280	$rcb = sub {
		1281	if ($cb) {
		1282	$w = _time;
		1283	&$cb;
		1284	$w = _time - $w;
		1285
		1286	# never use more then 50% of the time for the idle watcher,
		1287	# within some limits
		1288	$w = 0.0001 if $w < 0.0001;
		1289	$w = 5 if $w > 5;
		1290
		1291	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1292	} else {
		1293	# clean up...
		1294	undef $w;
		1295	undef $rcb;
		1296	}
		1297	};
		1298
		1299	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1300
		1301	bless \\$cb, "AnyEvent::Base::idle"
		1302	}
		1303
		1304	sub AnyEvent::Base::idle::DESTROY {
		1305	undef $${$_[0]};
1045	}	1306	}
1046		1307
1047	package AnyEvent::CondVar;	1308	package AnyEvent::CondVar;
1048		1309
1049	our @ISA = AnyEvent::CondVar::Base::;	1310	our @ISA = AnyEvent::CondVar::Base::;
…		…
1101	}	1362	}
1102		1363
1103	# undocumented/compatibility with pre-3.4	1364	# undocumented/compatibility with pre-3.4
1104	*broadcast = \&send;	1365	*broadcast = \&send;
1105	*wait = \&_wait;	1366	*wait = \&_wait;
		1367
		1368	=head1 ERROR AND EXCEPTION HANDLING
		1369
		1370	In general, AnyEvent does not do any error handling - it relies on the
		1371	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1372	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1373	checking of all AnyEvent methods, however, which is highly useful during
		1374	development.
		1375
		1376	As for exception handling (i.e. runtime errors and exceptions thrown while
		1377	executing a callback), this is not only highly event-loop specific, but
		1378	also not in any way wrapped by this module, as this is the job of the main
		1379	program.
		1380
		1381	The pure perl event loop simply re-throws the exception (usually
		1382	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1383	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1384	so on.
		1385
		1386	=head1 ENVIRONMENT VARIABLES
		1387
		1388	The following environment variables are used by this module or its
		1389	submodules.
		1390
		1391	Note that AnyEvent will remove I<all> environment variables starting with
		1392	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1393	enabled.
		1394
		1395	=over 4
		1396
		1397	=item C<PERL_ANYEVENT_VERBOSE>
		1398
		1399	By default, AnyEvent will be completely silent except in fatal
		1400	conditions. You can set this environment variable to make AnyEvent more
		1401	talkative.
		1402
		1403	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1404	conditions, such as not being able to load the event model specified by
		1405	C<PERL_ANYEVENT_MODEL>.
		1406
		1407	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1408	model it chooses.
		1409
		1410	=item C<PERL_ANYEVENT_STRICT>
		1411
		1412	AnyEvent does not do much argument checking by default, as thorough
		1413	argument checking is very costly. Setting this variable to a true value
		1414	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1415	check the arguments passed to most method calls. If it finds any problems,
		1416	it will croak.
		1417
		1418	In other words, enables "strict" mode.
		1419
		1420	Unlike C<use strict>, it is definitely recommended to keep it off in
		1421	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1422	developing programs can be very useful, however.
		1423
		1424	=item C<PERL_ANYEVENT_MODEL>
		1425
		1426	This can be used to specify the event model to be used by AnyEvent, before
		1427	auto detection and -probing kicks in. It must be a string consisting
		1428	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1429	and the resulting module name is loaded and if the load was successful,
		1430	used as event model. If it fails to load AnyEvent will proceed with
		1431	auto detection and -probing.
		1432
		1433	This functionality might change in future versions.
		1434
		1435	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1436	could start your program like this:
		1437
		1438	PERL_ANYEVENT_MODEL=Perl perl ...
		1439
		1440	=item C<PERL_ANYEVENT_PROTOCOLS>
		1441
		1442	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1443	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1444	of auto probing).
		1445
		1446	Must be set to a comma-separated list of protocols or address families,
		1447	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1448	used, and preference will be given to protocols mentioned earlier in the
		1449	list.
		1450
		1451	This variable can effectively be used for denial-of-service attacks
		1452	against local programs (e.g. when setuid), although the impact is likely
		1453	small, as the program has to handle conenction and other failures anyways.
		1454
		1455	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1456	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1457	- only support IPv4, never try to resolve or contact IPv6
		1458	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1459	IPv6, but prefer IPv6 over IPv4.
		1460
		1461	=item C<PERL_ANYEVENT_EDNS0>
		1462
		1463	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1464	for DNS. This extension is generally useful to reduce DNS traffic, but
		1465	some (broken) firewalls drop such DNS packets, which is why it is off by
		1466	default.
		1467
		1468	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1469	EDNS0 in its DNS requests.
		1470
		1471	=item C<PERL_ANYEVENT_MAX_FORKS>
		1472
		1473	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1474	will create in parallel.
		1475
		1476	=back
1106		1477
1107	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1478	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1108		1479
1109	This is an advanced topic that you do not normally need to use AnyEvent in	1480	This is an advanced topic that you do not normally need to use AnyEvent in
1110	a module. This section is only of use to event loop authors who want to	1481	a module. This section is only of use to event loop authors who want to
…		…
1144		1515
1145	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1516	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1146	condition variables: code blocking while waiting for a condition will	1517	condition variables: code blocking while waiting for a condition will
1147	C<die>. This still works with most modules/usages, and blocking calls must	1518	C<die>. This still works with most modules/usages, and blocking calls must
1148	not be done in an interactive application, so it makes sense.	1519	not be done in an interactive application, so it makes sense.
1149
1150	=head1 ENVIRONMENT VARIABLES
1151
1152	The following environment variables are used by this module:
1153
1154	=over 4
1155
1156	=item C<PERL_ANYEVENT_VERBOSE>
1157
1158	By default, AnyEvent will be completely silent except in fatal
1159	conditions. You can set this environment variable to make AnyEvent more
1160	talkative.
1161
1162	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1163	conditions, such as not being able to load the event model specified by
1164	C<PERL_ANYEVENT_MODEL>.
1165
1166	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1167	model it chooses.
1168
1169	=item C<PERL_ANYEVENT_MODEL>
1170
1171	This can be used to specify the event model to be used by AnyEvent, before
1172	auto detection and -probing kicks in. It must be a string consisting
1173	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1174	and the resulting module name is loaded and if the load was successful,
1175	used as event model. If it fails to load AnyEvent will proceed with
1176	auto detection and -probing.
1177
1178	This functionality might change in future versions.
1179
1180	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1181	could start your program like this:
1182
1183	PERL_ANYEVENT_MODEL=Perl perl ...
1184
1185	=item C<PERL_ANYEVENT_PROTOCOLS>
1186
1187	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1188	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1189	of auto probing).
1190
1191	Must be set to a comma-separated list of protocols or address families,
1192	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1193	used, and preference will be given to protocols mentioned earlier in the
1194	list.
1195
1196	This variable can effectively be used for denial-of-service attacks
1197	against local programs (e.g. when setuid), although the impact is likely
1198	small, as the program has to handle connection errors already-
1199
1200	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1201	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1202	- only support IPv4, never try to resolve or contact IPv6
1203	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1204	IPv6, but prefer IPv6 over IPv4.
1205
1206	=item C<PERL_ANYEVENT_EDNS0>
1207
1208	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1209	for DNS. This extension is generally useful to reduce DNS traffic, but
1210	some (broken) firewalls drop such DNS packets, which is why it is off by
1211	default.
1212
1213	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1214	EDNS0 in its DNS requests.
1215
1216	=item C<PERL_ANYEVENT_MAX_FORKS>
1217
1218	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1219	will create in parallel.
1220
1221	=back
1222		1520
1223	=head1 EXAMPLE PROGRAM	1521	=head1 EXAMPLE PROGRAM
1224		1522
1225	The following program uses an I/O watcher to read data from STDIN, a timer	1523	The following program uses an I/O watcher to read data from STDIN, a timer
1226	to display a message once per second, and a condition variable to quit the	1524	to display a message once per second, and a condition variable to quit the
…		…
1420	watcher.	1718	watcher.
1421		1719
1422	=head3 Results	1720	=head3 Results
1423		1721
1424	name watchers bytes create invoke destroy comment	1722	name watchers bytes create invoke destroy comment
1425	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1723	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1426	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1724	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1427	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1725	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1428	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1726	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1429	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1727	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1430	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1728	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1729	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1730	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1431	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1731	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1432	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1732	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1433	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1733	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1434	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1734	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1435		1735
1436	=head3 Discussion	1736	=head3 Discussion
1437		1737
1438	The benchmark does I<not> measure scalability of the event loop very	1738	The benchmark does I<not> measure scalability of the event loop very
1439	well. For example, a select-based event loop (such as the pure perl one)	1739	well. For example, a select-based event loop (such as the pure perl one)
…		…
1464	performance becomes really bad with lots of file descriptors (and few of	1764	performance becomes really bad with lots of file descriptors (and few of
1465	them active), of course, but this was not subject of this benchmark.	1765	them active), of course, but this was not subject of this benchmark.
1466		1766
1467	The C<Event> module has a relatively high setup and callback invocation	1767	The C<Event> module has a relatively high setup and callback invocation
1468	cost, but overall scores in on the third place.	1768	cost, but overall scores in on the third place.
		1769
		1770	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1771	when using its pure perl backend.
1469		1772
1470	C<Glib>'s memory usage is quite a bit higher, but it features a	1773	C<Glib>'s memory usage is quite a bit higher, but it features a
1471	faster callback invocation and overall ends up in the same class as	1774	faster callback invocation and overall ends up in the same class as
1472	C<Event>. However, Glib scales extremely badly, doubling the number of	1775	C<Event>. However, Glib scales extremely badly, doubling the number of
1473	watchers increases the processing time by more than a factor of four,	1776	watchers increases the processing time by more than a factor of four,
…		…
1551	it to another server. This includes deleting the old timeout and creating	1854	it to another server. This includes deleting the old timeout and creating
1552	a new one that moves the timeout into the future.	1855	a new one that moves the timeout into the future.
1553		1856
1554	=head3 Results	1857	=head3 Results
1555		1858
1556	name sockets create request	1859	name sockets create request
1557	EV 20000 69.01 11.16	1860	EV 20000 69.01 11.16
1558	Perl 20000 73.32 35.87	1861	Perl 20000 73.32 35.87
		1862	IOAsync 20000 157.00 98.14 epoll
		1863	IOAsync 20000 159.31 616.06 poll
1559	Event 20000 212.62 257.32	1864	Event 20000 212.62 257.32
1560	Glib 20000 651.16 1896.30	1865	Glib 20000 651.16 1896.30
1561	POE 20000 349.67 12317.24 uses POE::Loop::Event	1866	POE 20000 349.67 12317.24 uses POE::Loop::Event
1562		1867
1563	=head3 Discussion	1868	=head3 Discussion
1564		1869
1565	This benchmark I<does> measure scalability and overall performance of the	1870	This benchmark I<does> measure scalability and overall performance of the
1566	particular event loop.	1871	particular event loop.
…		…
1568	EV is again fastest. Since it is using epoll on my system, the setup time	1873	EV is again fastest. Since it is using epoll on my system, the setup time
1569	is relatively high, though.	1874	is relatively high, though.
1570		1875
1571	Perl surprisingly comes second. It is much faster than the C-based event	1876	Perl surprisingly comes second. It is much faster than the C-based event
1572	loops Event and Glib.	1877	loops Event and Glib.
		1878
		1879	IO::Async performs very well when using its epoll backend, and still quite
		1880	good compared to Glib when using its pure perl backend.
1573		1881
1574	Event suffers from high setup time as well (look at its code and you will	1882	Event suffers from high setup time as well (look at its code and you will
1575	understand why). Callback invocation also has a high overhead compared to	1883	understand why). Callback invocation also has a high overhead compared to
1576	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1884	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1577	uses select or poll in basically all documented configurations.	1885	uses select or poll in basically all documented configurations.
…		…
1640	=item * C-based event loops perform very well with small number of	1948	=item * C-based event loops perform very well with small number of
1641	watchers, as the management overhead dominates.	1949	watchers, as the management overhead dominates.
1642		1950
1643	=back	1951	=back
1644		1952
		1953	=head2 THE IO::Lambda BENCHMARK
		1954
		1955	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1956	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1957	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1958	shouldn't come as a surprise to anybody). As such, the benchmark is
		1959	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1960	very optimal. But how would AnyEvent compare when used without the extra
		1961	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1962
		1963	The benchmark itself creates an echo-server, and then, for 500 times,
		1964	connects to the echo server, sends a line, waits for the reply, and then
		1965	creates the next connection. This is a rather bad benchmark, as it doesn't
		1966	test the efficiency of the framework or much non-blocking I/O, but it is a
		1967	benchmark nevertheless.
		1968
		1969	name runtime
		1970	Lambda/select 0.330 sec
		1971	+ optimized 0.122 sec
		1972	Lambda/AnyEvent 0.327 sec
		1973	+ optimized 0.138 sec
		1974	Raw sockets/select 0.077 sec
		1975	POE/select, components 0.662 sec
		1976	POE/select, raw sockets 0.226 sec
		1977	POE/select, optimized 0.404 sec
		1978
		1979	AnyEvent/select/nb 0.085 sec
		1980	AnyEvent/EV/nb 0.068 sec
		1981	+state machine 0.134 sec
		1982
		1983	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1984	benchmarks actually make blocking connects and use 100% blocking I/O,
		1985	defeating the purpose of an event-based solution. All of the newly
		1986	written AnyEvent benchmarks use 100% non-blocking connects (using
		1987	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1988	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		1989	generally require a lot more bookkeeping and event handling than blocking
		1990	connects (which involve a single syscall only).
		1991
		1992	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1993	offers similar expressive power as POE and IO::Lambda, using conventional
		1994	Perl syntax. This means that both the echo server and the client are 100%
		1995	non-blocking, further placing it at a disadvantage.
		1996
		1997	As you can see, the AnyEvent + EV combination even beats the
		1998	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1999	backend easily beats IO::Lambda and POE.
		2000
		2001	And even the 100% non-blocking version written using the high-level (and
		2002	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2003	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2004	in a non-blocking way.
		2005
		2006	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2007	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2008	part of the IO::lambda distribution and were used without any changes.
		2009
		2010
		2011	=head1 SIGNALS
		2012
		2013	AnyEvent currently installs handlers for these signals:
		2014
		2015	=over 4
		2016
		2017	=item SIGCHLD
		2018
		2019	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2020	emulation for event loops that do not support them natively. Also, some
		2021	event loops install a similar handler.
		2022
		2023	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2024	reset it to default, to avoid losing child exit statuses.
		2025
		2026	=item SIGPIPE
		2027
		2028	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2029	when AnyEvent gets loaded.
		2030
		2031	The rationale for this is that AnyEvent users usually do not really depend
		2032	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2033	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2034	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2035	some random socket.
		2036
		2037	The rationale for installing a no-op handler as opposed to ignoring it is
		2038	that this way, the handler will be restored to defaults on exec.
		2039
		2040	Feel free to install your own handler, or reset it to defaults.
		2041
		2042	=back
		2043
		2044	=cut
		2045
		2046	undef $SIG{CHLD}
		2047	if $SIG{CHLD} eq 'IGNORE';
		2048
		2049	$SIG{PIPE} = sub { }
		2050	unless defined $SIG{PIPE};
1645		2051
1646	=head1 FORK	2052	=head1 FORK
1647		2053
1648	Most event libraries are not fork-safe. The ones who are usually are	2054	Most event libraries are not fork-safe. The ones who are usually are
1649	because they rely on inefficient but fork-safe C<select> or C<poll>	2055	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1669		2075
1670	use AnyEvent;	2076	use AnyEvent;
1671		2077
1672	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2078	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1673	be used to probe what backend is used and gain other information (which is	2079	be used to probe what backend is used and gain other information (which is
1674	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2080	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2081	$ENV{PERL_ANYEVENT_STRICT}.
		2082
		2083	Note that AnyEvent will remove I<all> environment variables starting with
		2084	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2085	enabled.
		2086
		2087
		2088	=head1 BUGS
		2089
		2090	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2091	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2092	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2093	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2094	pronounced).
1675		2095
1676		2096
1677	=head1 SEE ALSO	2097	=head1 SEE ALSO
1678		2098
1679	Utility functions: L<AnyEvent::Util>.	2099	Utility functions: L<AnyEvent::Util>.

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.155 by root, Fri Jun 6 07:07:01 2008 UTC vs. Revision 1.223 by root, Mon Jun 29 21:00:32 2009 UTC

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Revision 1.155 by root, Fri Jun 6 07:07:01 2008 UTC vs.
Revision 1.223 by root, Mon Jun 29 21:00:32 2009 UTC