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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC vs.
Revision 1.229 by root, Wed Jul 8 02:01:12 2009 UTC

…		…
1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
33		50
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
36		53
37	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
43		61
44	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
48	model you use.	66	model you use.
49		67
50	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
56		74
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
65		83
66	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
129	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
130	is in control).	148	is in control).
131		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
132	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
133	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	158	to it).
135		159
136	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
138	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
139	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
140		164
141	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
142		166
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
145	undef $w;	169	undef $w;
146	});	170	});
147		171
148	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
149	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
150	declared.	174	declared.
151		175
152	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
153		177
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
156		180
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (or a naked 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
359	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
360		414
361	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
362	pid => $pid,	416	pid => $pid,
363	cb => sub {	417	cb => sub {
364	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
365	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
366	$done->send;	420	$done->send;
367	},	421	},
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;
		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	});
372		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
…		…
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
		900	=item L<AnyEvent::HTTP>
		901
		902	A simple-to-use HTTP library that is capable of making a lot of concurrent
		903	HTTP requests.
		904
757	=item L<AnyEvent::HTTPD>	905	=item L<AnyEvent::HTTPD>
758		906
759	Provides a simple web application server framework.	907	Provides a simple web application server framework.
760		908
761	=item L<AnyEvent::FastPing>	909	=item L<AnyEvent::FastPing>
762		910
763	The fastest ping in the west.	911	The fastest ping in the west.
764		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
765	=item L<Net::IRC3>	937	=item L<AnyEvent::IRC>
766		938
767	AnyEvent based IRC client module family.	939	AnyEvent based IRC client module family (replacing the older Net::IRC3).
768		940
769	=item L<Net::XMPP2>	941	=item L<Net::XMPP2>
770		942
771	AnyEvent based XMPP (Jabber protocol) module family.	943	AnyEvent based XMPP (Jabber protocol) module family.
772		944
…		…
781		953
782	=item L<Coro>	954	=item L<Coro>
783		955
784	Has special support for AnyEvent via L<Coro::AnyEvent>.	956	Has special support for AnyEvent via L<Coro::AnyEvent>.
785		957
786	=item L<AnyEvent::AIO>, L<IO::AIO>
787
788	Truly asynchronous I/O, should be in the toolbox of every event
789	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
790	together.
791
792	=item L<AnyEvent::BDB>, L<BDB>
793
794	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
795	IO::AIO and AnyEvent together.
796
797	=item L<IO::Lambda>	958	=item L<IO::Lambda>
798		959
799	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.
800		961
801	=back	962	=back
…		…
803	=cut	964	=cut
804		965
805	package AnyEvent;	966	package AnyEvent;
806		967
807	no warnings;	968	no warnings;
808	use strict;	969	use strict qw(vars subs);
809		970
810	use Carp;	971	use Carp;
811		972
812	our $VERSION = 4.11;	973	our $VERSION = 4.8;
813	our $MODEL;	974	our $MODEL;
814		975
815	our $AUTOLOAD;	976	our $AUTOLOAD;
816	our @ISA;	977	our @ISA;
817		978
818	our @REGISTRY;	979	our @REGISTRY;
819		980
820	our $WIN32;	981	our $WIN32;
821		982
822	BEGIN {	983	BEGIN {
823	my $win32 = ! ! ($^O =~ /mswin32/i);	984	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
824	eval "sub WIN32(){ $win32 }";	985	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		986
		987	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		988	if ${^TAINT};
825	}	989	}
826		990
827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	991	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
828		992
829	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	993	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1011	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1012	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1013	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
850	[Wx:: => AnyEvent::Impl::POE::],	1014	[Wx:: => AnyEvent::Impl::POE::],
851	[Prima:: => AnyEvent::Impl::POE::],	1015	[Prima:: => AnyEvent::Impl::POE::],
		1016	# IO::Async is just too broken - we would need workaorunds for its
		1017	# byzantine signal and broken child handling, among others.
		1018	# IO::Async is rather hard to detect, as it doesn't have any
		1019	# obvious default class.
		1020	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1021	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1022	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
852	);	1023	);
853		1024
854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1025	our %method = map +($_ => 1),
		1026	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
855		1027
856	our @post_detect;	1028	our @post_detect;
857		1029
858	sub post_detect(&) {	1030	sub post_detect(&) {
859	my ($cb) = @_;	1031	my ($cb) = @_;
…		…
864	1	1036	1
865	} else {	1037	} else {
866	push @post_detect, $cb;	1038	push @post_detect, $cb;
867		1039
868	defined wantarray	1040	defined wantarray
869	? bless \$cb, "AnyEvent::Util::PostDetect"	1041	? bless \$cb, "AnyEvent::Util::postdetect"
870	: ()	1042	: ()
871	}	1043	}
872	}	1044	}
873		1045
874	sub AnyEvent::Util::PostDetect::DESTROY {	1046	sub AnyEvent::Util::postdetect::DESTROY {
875	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1047	@post_detect = grep $_ != ${$_[0]}, @post_detect;
876	}	1048	}
877		1049
878	sub detect() {	1050	sub detect() {
879	unless ($MODEL) {	1051	unless ($MODEL) {
…		…
916	last;	1088	last;
917	}	1089	}
918	}	1090	}
919		1091
920	$MODEL	1092	$MODEL
921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1093	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
922	}	1094	}
923	}	1095	}
924		1096
		1097	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1098
925	unshift @ISA, $MODEL;	1099	unshift @ISA, $MODEL;
926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1100
		1101	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927		1102
928	(shift @post_detect)->() while @post_detect;	1103	(shift @post_detect)->() while @post_detect;
929	}	1104	}
930		1105
931	$MODEL	1106	$MODEL
…		…
941		1116
942	my $class = shift;	1117	my $class = shift;
943	$class->$func (@_);	1118	$class->$func (@_);
944	}	1119	}
945		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, "<") : ($w, ">");
		1129
		1130	open my $fh2, "$mode&", $fh
		1131	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1132
		1133	# we assume CLOEXEC is already set by perl in all important cases
		1134
		1135	($fh2, $rw)
		1136	}
		1137
946	package AnyEvent::Base;	1138	package AnyEvent::Base;
947		1139
948	# default implementation for now and time	1140	# default implementations for many methods
949		1141
950	use Time::HiRes ();	1142	BEGIN {
		1143	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1144	*_time = \&Time::HiRes::time;
		1145	# if (eval "use POSIX (); (POSIX::times())...
		1146	} else {
		1147	*_time = sub { time }; # epic fail
		1148	}
		1149	}
951		1150
952	sub time { Time::HiRes::time }	1151	sub time { _time }
953	sub now { Time::HiRes::time }	1152	sub now { _time }
		1153	sub now_update { }
954		1154
955	# default implementation for ->condvar	1155	# default implementation for ->condvar
956		1156
957	sub condvar {	1157	sub condvar {
958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1158	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
959	}	1159	}
960		1160
961	# default implementation for ->signal	1161	# default implementation for ->signal
962		1162
963	our %SIG_CB;	1163	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1164
		1165	sub _signal_exec {
		1166	sysread $SIGPIPE_R, my $dummy, 4;
		1167
		1168	while (%SIG_EV) {
		1169	for (keys %SIG_EV) {
		1170	delete $SIG_EV{$_};
		1171	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1172	}
		1173	}
		1174	}
964		1175
965	sub signal {	1176	sub signal {
966	my (undef, %arg) = @_;	1177	my (undef, %arg) = @_;
967		1178
		1179	unless ($SIGPIPE_R) {
		1180	require Fcntl;
		1181
		1182	if (AnyEvent::WIN32) {
		1183	require AnyEvent::Util;
		1184
		1185	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1186	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1187	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1188	} else {
		1189	pipe $SIGPIPE_R, $SIGPIPE_W;
		1190	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1191	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1192
		1193	# not strictly required, as $^F is normally 2, but let's make sure...
		1194	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1195	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1196	}
		1197
		1198	$SIGPIPE_R
		1199	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1200
		1201	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1202	}
		1203
968	my $signal = uc $arg{signal}	1204	my $signal = uc $arg{signal}
969	or Carp::croak "required option 'signal' is missing";	1205	or Carp::croak "required option 'signal' is missing";
970		1206
971	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1207	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
972	$SIG{$signal} \|\|= sub {	1208	$SIG{$signal} \|\|= sub {
973	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1209	local $!;
		1210	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1211	undef $SIG_EV{$signal};
974	};	1212	};
975		1213
976	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1214	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
977	}	1215	}
978		1216
979	sub AnyEvent::Base::Signal::DESTROY {	1217	sub AnyEvent::Base::signal::DESTROY {
980	my ($signal, $cb) = @{$_[0]};	1218	my ($signal, $cb) = @{$_[0]};
981		1219
982	delete $SIG_CB{$signal}{$cb};	1220	delete $SIG_CB{$signal}{$cb};
983		1221
		1222	# delete doesn't work with older perls - they then
		1223	# print weird messages, or just unconditionally exit
		1224	# instead of getting the default action.
984	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1225	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
985	}	1226	}
986		1227
987	# default implementation for ->child	1228	# default implementation for ->child
988		1229
989	our %PID_CB;	1230	our %PID_CB;
990	our $CHLD_W;	1231	our $CHLD_W;
991	our $CHLD_DELAY_W;	1232	our $CHLD_DELAY_W;
992	our $PID_IDLE;
993	our $WNOHANG;	1233	our $WNOHANG;
994		1234
995	sub _child_wait {	1235	sub _sigchld {
996	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1236	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
997	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1237	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
998	(values %{ $PID_CB{0} \|\| {} });	1238	(values %{ $PID_CB{0} \|\| {} });
999	}	1239	}
1000
1001	undef $PID_IDLE;
1002	}
1003
1004	sub _sigchld {
1005	# make sure we deliver these changes "synchronous" with the event loop.
1006	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1007	undef $CHLD_DELAY_W;
1008	&_child_wait;
1009	});
1010	}	1240	}
1011		1241
1012	sub child {	1242	sub child {
1013	my (undef, %arg) = @_;	1243	my (undef, %arg) = @_;
1014		1244
1015	defined (my $pid = $arg{pid} + 0)	1245	defined (my $pid = $arg{pid} + 0)
1016	or Carp::croak "required option 'pid' is missing";	1246	or Carp::croak "required option 'pid' is missing";
1017		1247
1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1248	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1019		1249
1020	unless ($WNOHANG) {
1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1250	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1022	}
1023		1251
1024	unless ($CHLD_W) {	1252	unless ($CHLD_W) {
1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1253	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1026	# child could be a zombie already, so make at least one round	1254	# child could be a zombie already, so make at least one round
1027	&_sigchld;	1255	&_sigchld;
1028	}	1256	}
1029		1257
1030	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1258	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1031	}	1259	}
1032		1260
1033	sub AnyEvent::Base::Child::DESTROY {	1261	sub AnyEvent::Base::child::DESTROY {
1034	my ($pid, $cb) = @{$_[0]};	1262	my ($pid, $cb) = @{$_[0]};
1035		1263
1036	delete $PID_CB{$pid}{$cb};	1264	delete $PID_CB{$pid}{$cb};
1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1265	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1038		1266
1039	undef $CHLD_W unless keys %PID_CB;	1267	undef $CHLD_W unless keys %PID_CB;
		1268	}
		1269
		1270	# idle emulation is done by simply using a timer, regardless
		1271	# of whether the process is idle or not, and not letting
		1272	# the callback use more than 50% of the time.
		1273	sub idle {
		1274	my (undef, %arg) = @_;
		1275
		1276	my ($cb, $w, $rcb) = $arg{cb};
		1277
		1278	$rcb = sub {
		1279	if ($cb) {
		1280	$w = _time;
		1281	&$cb;
		1282	$w = _time - $w;
		1283
		1284	# never use more then 50% of the time for the idle watcher,
		1285	# within some limits
		1286	$w = 0.0001 if $w < 0.0001;
		1287	$w = 5 if $w > 5;
		1288
		1289	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1290	} else {
		1291	# clean up...
		1292	undef $w;
		1293	undef $rcb;
		1294	}
		1295	};
		1296
		1297	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1298
		1299	bless \\$cb, "AnyEvent::Base::idle"
		1300	}
		1301
		1302	sub AnyEvent::Base::idle::DESTROY {
		1303	undef $${$_[0]};
1040	}	1304	}
1041		1305
1042	package AnyEvent::CondVar;	1306	package AnyEvent::CondVar;
1043		1307
1044	our @ISA = AnyEvent::CondVar::Base::;	1308	our @ISA = AnyEvent::CondVar::Base::;
…		…
1096	}	1360	}
1097		1361
1098	# undocumented/compatibility with pre-3.4	1362	# undocumented/compatibility with pre-3.4
1099	*broadcast = \&send;	1363	*broadcast = \&send;
1100	*wait = \&_wait;	1364	*wait = \&_wait;
		1365
		1366	=head1 ERROR AND EXCEPTION HANDLING
		1367
		1368	In general, AnyEvent does not do any error handling - it relies on the
		1369	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1370	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1371	checking of all AnyEvent methods, however, which is highly useful during
		1372	development.
		1373
		1374	As for exception handling (i.e. runtime errors and exceptions thrown while
		1375	executing a callback), this is not only highly event-loop specific, but
		1376	also not in any way wrapped by this module, as this is the job of the main
		1377	program.
		1378
		1379	The pure perl event loop simply re-throws the exception (usually
		1380	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1381	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1382	so on.
		1383
		1384	=head1 ENVIRONMENT VARIABLES
		1385
		1386	The following environment variables are used by this module or its
		1387	submodules.
		1388
		1389	Note that AnyEvent will remove I<all> environment variables starting with
		1390	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1391	enabled.
		1392
		1393	=over 4
		1394
		1395	=item C<PERL_ANYEVENT_VERBOSE>
		1396
		1397	By default, AnyEvent will be completely silent except in fatal
		1398	conditions. You can set this environment variable to make AnyEvent more
		1399	talkative.
		1400
		1401	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1402	conditions, such as not being able to load the event model specified by
		1403	C<PERL_ANYEVENT_MODEL>.
		1404
		1405	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1406	model it chooses.
		1407
		1408	=item C<PERL_ANYEVENT_STRICT>
		1409
		1410	AnyEvent does not do much argument checking by default, as thorough
		1411	argument checking is very costly. Setting this variable to a true value
		1412	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1413	check the arguments passed to most method calls. If it finds any problems,
		1414	it will croak.
		1415
		1416	In other words, enables "strict" mode.
		1417
		1418	Unlike C<use strict>, it is definitely recommended to keep it off in
		1419	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1420	developing programs can be very useful, however.
		1421
		1422	=item C<PERL_ANYEVENT_MODEL>
		1423
		1424	This can be used to specify the event model to be used by AnyEvent, before
		1425	auto detection and -probing kicks in. It must be a string consisting
		1426	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1427	and the resulting module name is loaded and if the load was successful,
		1428	used as event model. If it fails to load AnyEvent will proceed with
		1429	auto detection and -probing.
		1430
		1431	This functionality might change in future versions.
		1432
		1433	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1434	could start your program like this:
		1435
		1436	PERL_ANYEVENT_MODEL=Perl perl ...
		1437
		1438	=item C<PERL_ANYEVENT_PROTOCOLS>
		1439
		1440	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1441	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1442	of auto probing).
		1443
		1444	Must be set to a comma-separated list of protocols or address families,
		1445	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1446	used, and preference will be given to protocols mentioned earlier in the
		1447	list.
		1448
		1449	This variable can effectively be used for denial-of-service attacks
		1450	against local programs (e.g. when setuid), although the impact is likely
		1451	small, as the program has to handle conenction and other failures anyways.
		1452
		1453	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1454	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1455	- only support IPv4, never try to resolve or contact IPv6
		1456	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1457	IPv6, but prefer IPv6 over IPv4.
		1458
		1459	=item C<PERL_ANYEVENT_EDNS0>
		1460
		1461	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1462	for DNS. This extension is generally useful to reduce DNS traffic, but
		1463	some (broken) firewalls drop such DNS packets, which is why it is off by
		1464	default.
		1465
		1466	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1467	EDNS0 in its DNS requests.
		1468
		1469	=item C<PERL_ANYEVENT_MAX_FORKS>
		1470
		1471	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1472	will create in parallel.
		1473
		1474	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1475
		1476	The default value for the C<max_outstanding> parameter for the default DNS
		1477	resolver - this is the maximum number of parallel DNS requests that are
		1478	sent to the DNS server.
		1479
		1480	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1481
		1482	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1483	configuration) in the default resolver. When set to the empty string, no
		1484	default config will be used.
		1485
		1486	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1487
		1488	When neither C<ca_file> nor C<ca_path> was specified during
		1489	L<AnyEvent::TLS> context creation, and either of these environment
		1490	variables exist, they will be used to specify CA certificate locations
		1491	instead of a system-dependent default.
		1492
		1493	=back
1101		1494
1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1495	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1103		1496
1104	This is an advanced topic that you do not normally need to use AnyEvent in	1497	This is an advanced topic that you do not normally need to use AnyEvent in
1105	a module. This section is only of use to event loop authors who want to	1498	a module. This section is only of use to event loop authors who want to
…		…
1139		1532
1140	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1533	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1141	condition variables: code blocking while waiting for a condition will	1534	condition variables: code blocking while waiting for a condition will
1142	C<die>. This still works with most modules/usages, and blocking calls must	1535	C<die>. This still works with most modules/usages, and blocking calls must
1143	not be done in an interactive application, so it makes sense.	1536	not be done in an interactive application, so it makes sense.
1144
1145	=head1 ENVIRONMENT VARIABLES
1146
1147	The following environment variables are used by this module:
1148
1149	=over 4
1150
1151	=item C<PERL_ANYEVENT_VERBOSE>
1152
1153	By default, AnyEvent will be completely silent except in fatal
1154	conditions. You can set this environment variable to make AnyEvent more
1155	talkative.
1156
1157	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1158	conditions, such as not being able to load the event model specified by
1159	C<PERL_ANYEVENT_MODEL>.
1160
1161	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1162	model it chooses.
1163
1164	=item C<PERL_ANYEVENT_MODEL>
1165
1166	This can be used to specify the event model to be used by AnyEvent, before
1167	auto detection and -probing kicks in. It must be a string consisting
1168	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1169	and the resulting module name is loaded and if the load was successful,
1170	used as event model. If it fails to load AnyEvent will proceed with
1171	auto detection and -probing.
1172
1173	This functionality might change in future versions.
1174
1175	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1176	could start your program like this:
1177
1178	PERL_ANYEVENT_MODEL=Perl perl ...
1179
1180	=item C<PERL_ANYEVENT_PROTOCOLS>
1181
1182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1184	of auto probing).
1185
1186	Must be set to a comma-separated list of protocols or address families,
1187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1188	used, and preference will be given to protocols mentioned earlier in the
1189	list.
1190
1191	This variable can effectively be used for denial-of-service attacks
1192	against local programs (e.g. when setuid), although the impact is likely
1193	small, as the program has to handle connection errors already-
1194
1195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1197	- only support IPv4, never try to resolve or contact IPv6
1198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1199	IPv6, but prefer IPv6 over IPv4.
1200
1201	=item C<PERL_ANYEVENT_EDNS0>
1202
1203	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1204	for DNS. This extension is generally useful to reduce DNS traffic, but
1205	some (broken) firewalls drop such DNS packets, which is why it is off by
1206	default.
1207
1208	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1209	EDNS0 in its DNS requests.
1210
1211	=item C<PERL_ANYEVENT_MAX_FORKS>
1212
1213	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1214	will create in parallel.
1215
1216	=back
1217		1537
1218	=head1 EXAMPLE PROGRAM	1538	=head1 EXAMPLE PROGRAM
1219		1539
1220	The following program uses an I/O watcher to read data from STDIN, a timer	1540	The following program uses an I/O watcher to read data from STDIN, a timer
1221	to display a message once per second, and a condition variable to quit the	1541	to display a message once per second, and a condition variable to quit the
…		…
1415	watcher.	1735	watcher.
1416		1736
1417	=head3 Results	1737	=head3 Results
1418		1738
1419	name watchers bytes create invoke destroy comment	1739	name watchers bytes create invoke destroy comment
1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1740	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1741	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1742	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1743	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1744	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1745	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1746	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1747	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1748	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1749	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1750	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1751	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1430		1752
1431	=head3 Discussion	1753	=head3 Discussion
1432		1754
1433	The benchmark does I<not> measure scalability of the event loop very	1755	The benchmark does I<not> measure scalability of the event loop very
1434	well. For example, a select-based event loop (such as the pure perl one)	1756	well. For example, a select-based event loop (such as the pure perl one)
…		…
1459	performance becomes really bad with lots of file descriptors (and few of	1781	performance becomes really bad with lots of file descriptors (and few of
1460	them active), of course, but this was not subject of this benchmark.	1782	them active), of course, but this was not subject of this benchmark.
1461		1783
1462	The C<Event> module has a relatively high setup and callback invocation	1784	The C<Event> module has a relatively high setup and callback invocation
1463	cost, but overall scores in on the third place.	1785	cost, but overall scores in on the third place.
		1786
		1787	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1788	when using its pure perl backend.
1464		1789
1465	C<Glib>'s memory usage is quite a bit higher, but it features a	1790	C<Glib>'s memory usage is quite a bit higher, but it features a
1466	faster callback invocation and overall ends up in the same class as	1791	faster callback invocation and overall ends up in the same class as
1467	C<Event>. However, Glib scales extremely badly, doubling the number of	1792	C<Event>. However, Glib scales extremely badly, doubling the number of
1468	watchers increases the processing time by more than a factor of four,	1793	watchers increases the processing time by more than a factor of four,
…		…
1546	it to another server. This includes deleting the old timeout and creating	1871	it to another server. This includes deleting the old timeout and creating
1547	a new one that moves the timeout into the future.	1872	a new one that moves the timeout into the future.
1548		1873
1549	=head3 Results	1874	=head3 Results
1550		1875
1551	name sockets create request	1876	name sockets create request
1552	EV 20000 69.01 11.16	1877	EV 20000 69.01 11.16
1553	Perl 20000 73.32 35.87	1878	Perl 20000 73.32 35.87
		1879	IOAsync 20000 157.00 98.14 epoll
		1880	IOAsync 20000 159.31 616.06 poll
1554	Event 20000 212.62 257.32	1881	Event 20000 212.62 257.32
1555	Glib 20000 651.16 1896.30	1882	Glib 20000 651.16 1896.30
1556	POE 20000 349.67 12317.24 uses POE::Loop::Event	1883	POE 20000 349.67 12317.24 uses POE::Loop::Event
1557		1884
1558	=head3 Discussion	1885	=head3 Discussion
1559		1886
1560	This benchmark I<does> measure scalability and overall performance of the	1887	This benchmark I<does> measure scalability and overall performance of the
1561	particular event loop.	1888	particular event loop.
…		…
1563	EV is again fastest. Since it is using epoll on my system, the setup time	1890	EV is again fastest. Since it is using epoll on my system, the setup time
1564	is relatively high, though.	1891	is relatively high, though.
1565		1892
1566	Perl surprisingly comes second. It is much faster than the C-based event	1893	Perl surprisingly comes second. It is much faster than the C-based event
1567	loops Event and Glib.	1894	loops Event and Glib.
		1895
		1896	IO::Async performs very well when using its epoll backend, and still quite
		1897	good compared to Glib when using its pure perl backend.
1568		1898
1569	Event suffers from high setup time as well (look at its code and you will	1899	Event suffers from high setup time as well (look at its code and you will
1570	understand why). Callback invocation also has a high overhead compared to	1900	understand why). Callback invocation also has a high overhead compared to
1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1901	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1572	uses select or poll in basically all documented configurations.	1902	uses select or poll in basically all documented configurations.
…		…
1635	=item * C-based event loops perform very well with small number of	1965	=item * C-based event loops perform very well with small number of
1636	watchers, as the management overhead dominates.	1966	watchers, as the management overhead dominates.
1637		1967
1638	=back	1968	=back
1639		1969
		1970	=head2 THE IO::Lambda BENCHMARK
		1971
		1972	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1973	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1974	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1975	shouldn't come as a surprise to anybody). As such, the benchmark is
		1976	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1977	very optimal. But how would AnyEvent compare when used without the extra
		1978	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1979
		1980	The benchmark itself creates an echo-server, and then, for 500 times,
		1981	connects to the echo server, sends a line, waits for the reply, and then
		1982	creates the next connection. This is a rather bad benchmark, as it doesn't
		1983	test the efficiency of the framework or much non-blocking I/O, but it is a
		1984	benchmark nevertheless.
		1985
		1986	name runtime
		1987	Lambda/select 0.330 sec
		1988	+ optimized 0.122 sec
		1989	Lambda/AnyEvent 0.327 sec
		1990	+ optimized 0.138 sec
		1991	Raw sockets/select 0.077 sec
		1992	POE/select, components 0.662 sec
		1993	POE/select, raw sockets 0.226 sec
		1994	POE/select, optimized 0.404 sec
		1995
		1996	AnyEvent/select/nb 0.085 sec
		1997	AnyEvent/EV/nb 0.068 sec
		1998	+state machine 0.134 sec
		1999
		2000	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2001	benchmarks actually make blocking connects and use 100% blocking I/O,
		2002	defeating the purpose of an event-based solution. All of the newly
		2003	written AnyEvent benchmarks use 100% non-blocking connects (using
		2004	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2005	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2006	generally require a lot more bookkeeping and event handling than blocking
		2007	connects (which involve a single syscall only).
		2008
		2009	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2010	offers similar expressive power as POE and IO::Lambda, using conventional
		2011	Perl syntax. This means that both the echo server and the client are 100%
		2012	non-blocking, further placing it at a disadvantage.
		2013
		2014	As you can see, the AnyEvent + EV combination even beats the
		2015	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2016	backend easily beats IO::Lambda and POE.
		2017
		2018	And even the 100% non-blocking version written using the high-level (and
		2019	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2020	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2021	in a non-blocking way.
		2022
		2023	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2024	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2025	part of the IO::lambda distribution and were used without any changes.
		2026
		2027
		2028	=head1 SIGNALS
		2029
		2030	AnyEvent currently installs handlers for these signals:
		2031
		2032	=over 4
		2033
		2034	=item SIGCHLD
		2035
		2036	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2037	emulation for event loops that do not support them natively. Also, some
		2038	event loops install a similar handler.
		2039
		2040	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2041	reset it to default, to avoid losing child exit statuses.
		2042
		2043	=item SIGPIPE
		2044
		2045	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2046	when AnyEvent gets loaded.
		2047
		2048	The rationale for this is that AnyEvent users usually do not really depend
		2049	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2050	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2051	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2052	some random socket.
		2053
		2054	The rationale for installing a no-op handler as opposed to ignoring it is
		2055	that this way, the handler will be restored to defaults on exec.
		2056
		2057	Feel free to install your own handler, or reset it to defaults.
		2058
		2059	=back
		2060
		2061	=cut
		2062
		2063	undef $SIG{CHLD}
		2064	if $SIG{CHLD} eq 'IGNORE';
		2065
		2066	$SIG{PIPE} = sub { }
		2067	unless defined $SIG{PIPE};
1640		2068
1641	=head1 FORK	2069	=head1 FORK
1642		2070
1643	Most event libraries are not fork-safe. The ones who are usually are	2071	Most event libraries are not fork-safe. The ones who are usually are
1644	because they rely on inefficient but fork-safe C<select> or C<poll>	2072	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1658	specified in the variable.	2086	specified in the variable.
1659		2087
1660	You can make AnyEvent completely ignore this variable by deleting it	2088	You can make AnyEvent completely ignore this variable by deleting it
1661	before the first watcher gets created, e.g. with a C<BEGIN> block:	2089	before the first watcher gets created, e.g. with a C<BEGIN> block:
1662		2090
1663	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2091	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1664		2092
1665	use AnyEvent;	2093	use AnyEvent;
1666		2094
1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2095	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1668	be used to probe what backend is used and gain other information (which is	2096	be used to probe what backend is used and gain other information (which is
1669	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2097	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2098	$ENV{PERL_ANYEVENT_STRICT}.
		2099
		2100	Note that AnyEvent will remove I<all> environment variables starting with
		2101	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2102	enabled.
		2103
		2104
		2105	=head1 BUGS
		2106
		2107	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2108	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2109	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2110	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2111	pronounced).
1670		2112
1671		2113
1672	=head1 SEE ALSO	2114	=head1 SEE ALSO
1673		2115
1674	Utility functions: L<AnyEvent::Util>.	2116	Utility functions: L<AnyEvent::Util>.
…		…
1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2133	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1692		2134
1693		2135
1694	=head1 AUTHOR	2136	=head1 AUTHOR
1695		2137
1696	Marc Lehmann <schmorp@schmorp.de>	2138	Marc Lehmann <schmorp@schmorp.de>
1697	http://home.schmorp.de/	2139	http://home.schmorp.de/
1698		2140
1699	=cut	2141	=cut
1700		2142
1701	1	2143	1
1702		2144

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC vs. Revision 1.229 by root, Wed Jul 8 02:01:12 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC vs.
Revision 1.229 by root, Wed Jul 8 02:01:12 2009 UTC