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Revision 1.279 by root, Sun Aug 9 16:05:11 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
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
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
28		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
33		58
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
36		61
37	First and foremost, I<AnyEvent is not an event model> itself, it only	62	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	63	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,	64	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,	65	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	66	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
43		69
44	The goal of AnyEvent is to offer module authors the ability to do event	70	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	71	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	72	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	73	module users into the same thing by forcing them to use the same event
48	model you use.	74	model you use.
49		75
50	For modules like POE or IO::Async (which is a total misnomer as it is	76	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	77	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	78	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	79	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	80	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.	81	module are I<also> forced to use the same event loop you use.
56		82
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	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	85	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,	86	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	87	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	88	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	89	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).	90	to AnyEvent, too, so it is future-proof).
65		91
66	In addition to being free of having to use I<the one and only true event	92	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	93	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	94	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	95	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	153	These watchers are normal Perl objects with normal Perl lifetime. After
128	creating a watcher it will immediately "watch" for events and invoke the	154	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	155	callback when the event occurs (of course, only when the event model
130	is in control).	156	is in control).
131		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
132	To disable the watcher you have to destroy it (e.g. by setting the	164	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	165	variable you store it in to C<undef> or otherwise deleting all references
134	to it).	166	to it).
135		167
136	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
138	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
139	example), or need to refer to their watcher object in other ways.	171	example), or need to refer to their watcher object in other ways.
140		172
141	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
142		174
143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
144	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
145	undef $w;	177	undef $w;
146	});	178	});
147		179
148	Note that C<my $w; $w => combination. This is necessary because in Perl,	180	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	181	my variables are only visible after the statement in which they are
150	declared.	182	declared.
151		183
152	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
153		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	192	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
156		194
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	195	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		196	for events (AnyEvent might or might not keep a reference to this file
		197	handle). Note that only file handles pointing to things for which
		198	non-blocking operation makes sense are allowed. This includes sockets,
		199	most character devices, pipes, fifos and so on, but not for example files
		200	or block devices.
		201
158	for events. C<poll> must be a string that is either C<r> or C<w>,	202	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,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
160	respectively. C<cb> is the callback to invoke each time the file handle	205	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		206
163	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
166		210
…		…
170		214
171	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
172	always use non-blocking calls when reading/writing from/to your file	216	always use non-blocking calls when reading/writing from/to your file
173	handles.	217	handles.
174		218
175	Example:
176
177	# wait for readability of STDIN, then read a line and disable the watcher	219	Example: wait for readability of STDIN, then read a line and disable the
		220	watcher.
		221
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	224	warn "read: $input\n";
181	undef $w;	225	undef $w;
182	});	226	});
183		227
184	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
185		229
		230	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		231
		232	$w = AnyEvent->timer (
		233	after => <fractional_seconds>,
		234	interval => <fractional_seconds>,
		235	cb => <callback>,
		236	);
		237
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	238	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	239	method with the following mandatory arguments:
188		240
189	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
190	supported) the callback should be invoked. C<cb> is the callback to invoke	242	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
192		244
193	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
196		248
197	The timer callback will be invoked at most once: if you want a repeating	249	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	250	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	251	callback will be invoked regularly at that interval (in fractional
		252	seconds) after the first invocation. If C<interval> is specified with a
		253	false value, then it is treated as if it were missing.
200		254
201	Example:	255	The callback will be rescheduled before invoking the callback, but no
		256	attempt is done to avoid timer drift in most backends, so the interval is
		257	only approximate.
202		258
203	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	262	warn "timeout\n";
206	});	263	});
207		264
208	# to cancel the timer:	265	# to cancel the timer:
209	undef $w;	266	undef $w;
210		267
211	Example 2:
212
213	# fire an event after 0.5 seconds, then roughly every second	268	Example 2: fire an event after 0.5 seconds, then roughly every second.
214	my $w;
215		269
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
219	};	272	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		273
224	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
225		275
226	There are two ways to handle timers: based on real time (relative, "fire	276	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	277	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	350	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	351	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	353	account.
304		354
		355	=item AnyEvent->now_update
		356
		357	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		358	the current time for each loop iteration (see the discussion of L<<
		359	AnyEvent->now >>, above).
		360
		361	When a callback runs for a long time (or when the process sleeps), then
		362	this "current" time will differ substantially from the real time, which
		363	might affect timers and time-outs.
		364
		365	When this is the case, you can call this method, which will update the
		366	event loop's idea of "current time".
		367
		368	Note that updating the time I<might> cause some events to be handled.
		369
305	=back	370	=back
306		371
307	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
308		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
309	You can watch for signals using a signal watcher, C<signal> is the signal	376	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	377	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311	be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
312		379
313	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	381	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	382	callbacks cannot use arguments passed to signal watcher callbacks.
316		383
…		…
318	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
319	that it might take a while until the signal gets handled by the process,	386	that it might take a while until the signal gets handled by the process,
320	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
321		388
322	The main advantage of using these watchers is that you can share a signal	389	The main advantage of using these watchers is that you can share a signal
323	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
324		392
325	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
326	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
327		396
328	Example: exit on SIGINT	397	Example: exit on SIGINT
329		398
330	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
331		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		409	variable can be changed only before the first signal watcher is created,
		410	and should be left alone otherwise. This variable determines how often
		411	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		412	will cause fewer spurious wake-ups, which is better for power and CPU
		413	saving.
		414
		415	All these problems can be avoided by installing the optional
		416	L<Async::Interrupt> module, which works with most event loops. It will not
		417	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		418	(and not with L<POE> currently, as POE does it's own workaround with
		419	one-second latency). For those, you just have to suffer the delays.
		420
332	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
333		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
334	You can also watch on a child process exit and catch its exit status.	425	You can also watch on a child process exit and catch its exit status.
335		426
336	The child process is specified by the C<pid> argument (if set to C<0>, it	427	The child process is specified by the C<pid> argument (one some backends,
337	watches for any child process exit). The watcher will trigger as often	428	using C<0> watches for any child process exit, on others this will
338	as status change for the child are received. This works by installing a	429	croak). The watcher will be triggered only when the child process has
339	signal handler for C<SIGCHLD>. The callback will be called with the pid	430	finished and an exit status is available, not on any trace events
340	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
341	you I<can> rely on child watcher callback arguments.	432
		433	The callback will be called with the pid and exit status (as returned by
		434	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		435	callback arguments.
		436
		437	This watcher type works by installing a signal handler for C<SIGCHLD>,
		438	and since it cannot be shared, nothing else should use SIGCHLD or reap
		439	random child processes (waiting for specific child processes, e.g. inside
		440	C<system>, is just fine).
342		441
343	There is a slight catch to child watchers, however: you usually start them	442	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	443	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
346		445
347	Not all event models handle this correctly (POE doesn't), but even for	446	Not all event models handle this correctly (neither POE nor IO::Async do,
		447	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	448	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).	449	the process exits (i.e. before you fork in the first place). AnyEvent's
		450	pure perl event loop handles all cases correctly regardless of when you
		451	start the watcher.
350		452
351	This means you cannot create a child watcher as the very first thing in an	453	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	454	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>).	455	watcher before you C<fork> the child (alternatively, you can call
		456	C<AnyEvent::detect>).
		457
		458	As most event loops do not support waiting for child events, they will be
		459	emulated by AnyEvent in most cases, in which the latency and race problems
		460	mentioned in the description of signal watchers apply.
354		461
355	Example: fork a process and wait for it	462	Example: fork a process and wait for it
356		463
357	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
358		465
359	my $pid = fork or exit 5;	466	my $pid = fork or exit 5;
360		467
361	my $w = AnyEvent->child (	468	my $w = AnyEvent->child (
362	pid => $pid,	469	pid => $pid,
363	cb => sub {	470	cb => sub {
364	my ($pid, $status) = @_;	471	my ($pid, $status) = @_;
365	warn "pid $pid exited with status $status";	472	warn "pid $pid exited with status $status";
366	$done->send;	473	$done->send;
367	},	474	},
368	);	475	);
369		476
370	# do something else, then wait for process exit	477	# do something else, then wait for process exit
371	$done->recv;	478	$done->recv;
		479
		480	=head2 IDLE WATCHERS
		481
		482	$w = AnyEvent->idle (cb => <callback>);
		483
		484	Sometimes there is a need to do something, but it is not so important
		485	to do it instantly, but only when there is nothing better to do. This
		486	"nothing better to do" is usually defined to be "no other events need
		487	attention by the event loop".
		488
		489	Idle watchers ideally get invoked when the event loop has nothing
		490	better to do, just before it would block the process to wait for new
		491	events. Instead of blocking, the idle watcher is invoked.
		492
		493	Most event loops unfortunately do not really support idle watchers (only
		494	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		495	will simply call the callback "from time to time".
		496
		497	Example: read lines from STDIN, but only process them when the
		498	program is otherwise idle:
		499
		500	my @lines; # read data
		501	my $idle_w;
		502	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		503	push @lines, scalar <STDIN>;
		504
		505	# start an idle watcher, if not already done
		506	$idle_w ||= AnyEvent->idle (cb => sub {
		507	# handle only one line, when there are lines left
		508	if (my $line = shift @lines) {
		509	print "handled when idle: $line";
		510	} else {
		511	# otherwise disable the idle watcher again
		512	undef $idle_w;
		513	}
		514	});
		515	});
372		516
373	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
374		523
375	If you are familiar with some event loops you will know that all of them	524	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	525	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
378		527
379	AnyEvent is different, it expects somebody else to run the event loop and	528	AnyEvent is slightly different: it expects somebody else to run the event
380	will only block when necessary (usually when told by the user).	529	loop and will only block when necessary (usually when told by the user).
381		530
382	The instrument to do that is called a "condition variable", so called	531	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	532	because they represent a condition that must become true.
		533
		534	Now is probably a good time to look at the examples further below.
384		535
385	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
387	C<cb>, which specifies a callback to be called when the condition variable	538	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
389		541
390	After creation, the condition variable is "false" until it becomes "true"	542	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	543	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<<	544	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	545	->send >> method).
…		…
395	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
396	optionally wait for them. They can also be called merge points - points	548	optionally wait for them. They can also be called merge points - points
397	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
398	another way to call them is transactions - each condition variable can be	550	another way to call them is transactions - each condition variable can be
399	used to represent a transaction, which finishes at some point and delivers	551	used to represent a transaction, which finishes at some point and delivers
400	a result.	552	a result. And yet some people know them as "futures" - a promise to
		553	compute/deliver something that you can wait for.
401		554
402	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
403	for example, if you write a module that does asynchronous http requests,	556	for example, if you write a module that does asynchronous http requests,
404	then a condition variable would be the ideal candidate to signal the	557	then a condition variable would be the ideal candidate to signal the
405	availability of results. The user can either act when the callback is	558	availability of results. The user can either act when the callback is
…		…
439	after => 1,	592	after => 1,
440	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
441	);	594	);
442		595
443	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
444	# calls send	597	# calls -<send
445	$result_ready->recv;	598	$result_ready->recv;
446		599
447	Example: wait for a timer, but take advantage of the fact that	600	Example: wait for a timer, but take advantage of the fact that condition
448	condition variables are also code references.	601	variables are also callable directly.
449		602
450	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	605	$done->recv;
		606
		607	Example: Imagine an API that returns a condvar and doesn't support
		608	callbacks. This is how you make a synchronous call, for example from
		609	the main program:
		610
		611	use AnyEvent::CouchDB;
		612
		613	...
		614
		615	my @info = $couchdb->info->recv;
		616
		617	And this is how you would just set a callback to be called whenever the
		618	results are available:
		619
		620	$couchdb->info->cb (sub {
		621	my @info = $_[0]->recv;
		622	});
453		623
454	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
455		625
456	These methods should only be used by the producing side, i.e. the	626	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	627	code/module that eventually sends the signal. Note that it is also
…		…
470	immediately from within send.	640	immediately from within send.
471		641
472	Any arguments passed to the C<send> call will be returned by all	642	Any arguments passed to the C<send> call will be returned by all
473	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
474		644
475	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
476	(as a code reference). Calling them directly is the same as calling	646	they were a code reference). Calling them directly is the same as calling
477	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
478	overloading, so as tempting as it may be, passing a condition variable
479	instead of a callback does not work. Both the pure perl and EV loops
480	support overloading, however, as well as all functions that use perl to
481	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
482	example).
483		648
484	=item $cv->croak ($error)	649	=item $cv->croak ($error)
485		650
486	Similar to send, but causes all call's to C<< ->recv >> to invoke	651	Similar to send, but causes all call's to C<< ->recv >> to invoke
487	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
488		653
489	This can be used to signal any errors to the condition variable	654	This can be used to signal any errors to the condition variable
490	user/consumer.	655	user/consumer. Doing it this way instead of calling C<croak> directly
		656	delays the error detetcion, but has the overwhelmign advantage that it
		657	diagnoses the error at the place where the result is expected, and not
		658	deep in some event clalback without connection to the actual code causing
		659	the problem.
491		660
492	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
493		662
494	=item $cv->end	663	=item $cv->end
495
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497		664
498	These two methods can be used to combine many transactions/events into	665	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	666	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
501		668
…		…
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	670	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	671	>>, 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	672	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.	673	callback was set, C<send> will be called without any arguments.
507		674
508	Let's clarify this with the ping example:	675	You can think of C<< $cv->send >> giving you an OR condition (one call
		676	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		677	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		678
		679	Let's start with a simple example: you have two I/O watchers (for example,
		680	STDOUT and STDERR for a program), and you want to wait for both streams to
		681	close before activating a condvar:
		682
		683	my $cv = AnyEvent->condvar;
		684
		685	$cv->begin; # first watcher
		686	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		687	defined sysread $fh1, my $buf, 4096
		688	or $cv->end;
		689	});
		690
		691	$cv->begin; # second watcher
		692	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		693	defined sysread $fh2, my $buf, 4096
		694	or $cv->end;
		695	});
		696
		697	$cv->recv;
		698
		699	This works because for every event source (EOF on file handle), there is
		700	one call to C<begin>, so the condvar waits for all calls to C<end> before
		701	sending.
		702
		703	The ping example mentioned above is slightly more complicated, as the
		704	there are results to be passwd back, and the number of tasks that are
		705	begung can potentially be zero:
509		706
510	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
511		708
512	my %result;	709	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
533	loop, which serves two important purposes: first, it sets the callback	730	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	731	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	732	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	733	doesn't execute once).
537		734
538	This is the general pattern when you "fan out" into multiple subrequests:	735	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>	736	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	737	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>.	738	subrequest you start, call C<begin> and for each subrequest you finish,
		739	call C<end>.
542		740
543	=back	741	=back
544		742
545	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
546		744
…		…
562	function will call C<croak>.	760	function will call C<croak>.
563		761
564	In list context, all parameters passed to C<send> will be returned,	762	In list context, all parameters passed to C<send> will be returned,
565	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
566		764
		765	Note that doing a blocking wait in a callback is not supported by any
		766	event loop, that is, recursive invocation of a blocking C<< ->recv
		767	>> is not allowed, and the C<recv> call will C<croak> if such a
		768	condition is detected. This condition can be slightly loosened by using
		769	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		770	any thread that doesn't run the event loop itself.
		771
567	Not all event models support a blocking wait - some die in that case	772	Not all event models support a blocking wait - some die in that case
568	(programs might want to do that to stay interactive), so I<if you are	773	(programs might want to do that to stay interactive), so I<if you are
569	using this from a module, never require a blocking wait>, but let the	774	using this from a module, never require a blocking wait>. Instead, let the
570	caller decide whether the call will block or not (for example, by coupling	775	caller decide whether the call will block or not (for example, by coupling
571	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
572	callbacks so the caller knows that getting the result will not block,	777	callbacks so the caller knows that getting the result will not block,
573	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
574		779
575	Another reason I<never> to C<< ->recv >> in a module is that you cannot
576	sensibly have two C<< ->recv >>'s in parallel, as that would require
577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
578	can supply.
579
580	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
581	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
582	versions and also integrates coroutines into AnyEvent, making blocking
583	C<< ->recv >> calls perfectly safe as long as they are done from another
584	coroutine (one that doesn't run the event loop).
585
586	You can ensure that C<< -recv >> never blocks by setting a callback and	780	You can ensure that C<< -recv >> never blocks by setting a callback and
587	only calling C<< ->recv >> from within that callback (or at a later	781	only calling C<< ->recv >> from within that callback (or at a later
588	time). This will work even when the event loop does not support blocking	782	time). This will work even when the event loop does not support blocking
589	waits otherwise.	783	waits otherwise.
590		784
591	=item $bool = $cv->ready	785	=item $bool = $cv->ready
592		786
593	Returns true when the condition is "true", i.e. whether C<send> or	787	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	788	C<croak> have been called.
595		789
596	=item $cb = $cv->cb ([new callback])	790	=item $cb = $cv->cb ($cb->($cv))
597		791
598	This is a mutator function that returns the callback set and optionally	792	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	793	replaces it before doing so.
600		794
601	The callback will be called when the condition becomes "true", i.e. when	795	The callback will be called when the condition becomes (or already was)
602	C<send> or C<croak> are called, with the only argument being the condition	796	"true", i.e. when C<send> or C<croak> are called (or were called), with
603	variable itself. Calling C<recv> inside the callback or at any later time	797	the only argument being the condition variable itself. Calling C<recv>
604	is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
605		799
606	=back	800	=back
607		801
		802	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		803
		804	The available backend classes are (every class has its own manpage):
		805
		806	=over 4
		807
		808	=item Backends that are autoprobed when no other event loop can be found.
		809
		810	EV is the preferred backend when no other event loop seems to be in
		811	use. If EV is not installed, then AnyEvent will fall back to its own
		812	pure-perl implementation, which is available everywhere as it comes with
		813	AnyEvent itself.
		814
		815	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		816	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		817
		818	=item Backends that are transparently being picked up when they are used.
		819
		820	These will be used when they are currently loaded when the first watcher
		821	is created, in which case it is assumed that the application is using
		822	them. This means that AnyEvent will automatically pick the right backend
		823	when the main program loads an event module before anything starts to
		824	create watchers. Nothing special needs to be done by the main program.
		825
		826	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		827	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		828	AnyEvent::Impl::Tk based on Tk, very broken.
		829	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		830	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		831	AnyEvent::Impl::Irssi used when running within irssi.
		832
		833	=item Backends with special needs.
		834
		835	Qt requires the Qt::Application to be instantiated first, but will
		836	otherwise be picked up automatically. As long as the main program
		837	instantiates the application before any AnyEvent watchers are created,
		838	everything should just work.
		839
		840	AnyEvent::Impl::Qt based on Qt.
		841
		842	Support for IO::Async can only be partial, as it is too broken and
		843	architecturally limited to even support the AnyEvent API. It also
		844	is the only event loop that needs the loop to be set explicitly, so
		845	it can only be used by a main program knowing about AnyEvent. See
		846	L<AnyEvent::Impl::Async> for the gory details.
		847
		848	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		849
		850	=item Event loops that are indirectly supported via other backends.
		851
		852	Some event loops can be supported via other modules:
		853
		854	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		855
		856	B<WxWidgets> has no support for watching file handles. However, you can
		857	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		858	polls 20 times per second, which was considered to be too horrible to even
		859	consider for AnyEvent.
		860
		861	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		862	backend, so it can be supported through POE.
		863
		864	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		865	load L<POE> when detecting them, in the hope that POE will pick them up,
		866	in which case everything will be automatic.
		867
		868	=back
		869
608	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
609		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
610	=over 4	875	=over 4
611		876
612	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
613		878
614	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
615	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
616	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
619		886	will be C<urxvt::anyevent>).
620	The known classes so far are:
621
622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
623	AnyEvent::Impl::Event based on Event, second best choice.
624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
625	AnyEvent::Impl::Glib based on Glib, third-best choice.
626	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630
631	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
636	it's adaptor.
637
638	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
639	autodetecting them.
640		887
641	=item AnyEvent::detect	888	=item AnyEvent::detect
642		889
643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
644	if necessary. You should only call this function right before you would	891	if necessary. You should only call this function right before you would
645	have created an AnyEvent watcher anyway, that is, as late as possible at	892	have created an AnyEvent watcher anyway, that is, as late as possible at
646	runtime.	893	runtime, and not e.g. while initialising of your module.
		894
		895	If you need to do some initialisation before AnyEvent watchers are
		896	created, use C<post_detect>.
647		897
648	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
649		899
650	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
651	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
652		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		905	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		906	other initialisations - see the sources of L<AnyEvent::Strict> or
		907	L<AnyEvent::AIO> to see how this is used.
		908
		909	The most common usage is to create some global watchers, without forcing
		910	event module detection too early, for example, L<AnyEvent::AIO> creates
		911	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		912	avoid autodetecting the event module at load time.
		913
653	If called in scalar or list context, then it creates and returns an object	914	If called in scalar or list context, then it creates and returns an object
654	that automatically removes the callback again when it is destroyed. See	915	that automatically removes the callback again when it is destroyed (or
		916	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
655	L<Coro::BDB> for a case where this is useful.	917	a case where this is useful.
		918
		919	Example: Create a watcher for the IO::AIO module and store it in
		920	C<$WATCHER>. Only do so after the event loop is initialised, though.
		921
		922	our WATCHER;
		923
		924	my $guard = AnyEvent::post_detect {
		925	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		926	};
		927
		928	# the ||= is important in case post_detect immediately runs the block,
		929	# as to not clobber the newly-created watcher. assigning both watcher and
		930	# post_detect guard to the same variable has the advantage of users being
		931	# able to just C<undef $WATCHER> if the watcher causes them grief.
		932
		933	$WATCHER ||= $guard;
656		934
657	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
658		936
659	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
660	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
661	the event loop has been chosen.	939	the event loop has been chosen.
662		940
663	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	You should check C<$AnyEvent::MODEL> before adding to this array, though:
664	if it contains a true value then the event loop has already been detected,	942	if it is defined then the event loop has already been detected, and the
665	and the array will be ignored.	943	array will be ignored.
666		944
667	Best use C<AnyEvent::post_detect { BLOCK }> instead.	945	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		946	it,as it takes care of these details.
		947
		948	This variable is mainly useful for modules that can do something useful
		949	when AnyEvent is used and thus want to know when it is initialised, but do
		950	not need to even load it by default. This array provides the means to hook
		951	into AnyEvent passively, without loading it.
668		952
669	=back	953	=back
670		954
671	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
672		956
…		…
727		1011
728		1012
729	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
730		1014
731	The following is a non-exhaustive list of additional modules that use	1015	The following is a non-exhaustive list of additional modules that use
732	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1016	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
733	in the same program. Some of the modules come with AnyEvent, some are	1017	modules and other event loops in the same program. Some of the modules
734	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
735		1019
736	=over 4	1020	=over 4
737		1021
738	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
739		1023
740	Contains various utility functions that replace often-used but blocking	1024	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	1025	functions such as C<inet_aton> by event-/callback-based versions.
742
743	=item L<AnyEvent::Handle>
744
745	Provide read and write buffers and manages watchers for reads and writes.
746		1026
747	=item L<AnyEvent::Socket>	1027	=item L<AnyEvent::Socket>
748		1028
749	Provides various utility functions for (internet protocol) sockets,	1029	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	1030	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	1031	connections or tcp servers, with IPv6 and SRV record support and more.
752		1032
		1033	=item L<AnyEvent::Handle>
		1034
		1035	Provide read and write buffers, manages watchers for reads and writes,
		1036	supports raw and formatted I/O, I/O queued and fully transparent and
		1037	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		1038
753	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
754		1040
755	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
756		1042
		1043	=item L<AnyEvent::HTTP>
		1044
		1045	A simple-to-use HTTP library that is capable of making a lot of concurrent
		1046	HTTP requests.
		1047
757	=item L<AnyEvent::HTTPD>	1048	=item L<AnyEvent::HTTPD>
758		1049
759	Provides a simple web application server framework.	1050	Provides a simple web application server framework.
760		1051
761	=item L<AnyEvent::FastPing>	1052	=item L<AnyEvent::FastPing>
762		1053
763	The fastest ping in the west.	1054	The fastest ping in the west.
764		1055
		1056	=item L<AnyEvent::DBI>
		1057
		1058	Executes L<DBI> requests asynchronously in a proxy process.
		1059
		1060	=item L<AnyEvent::AIO>
		1061
		1062	Truly asynchronous I/O, should be in the toolbox of every event
		1063	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1064	together.
		1065
		1066	=item L<AnyEvent::BDB>
		1067
		1068	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1069	L<BDB> and AnyEvent together.
		1070
		1071	=item L<AnyEvent::GPSD>
		1072
		1073	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1074
765	=item L<Net::IRC3>	1075	=item L<AnyEvent::IRC>
766		1076
767	AnyEvent based IRC client module family.	1077	AnyEvent based IRC client module family (replacing the older Net::IRC3).
768		1078
769	=item L<Net::XMPP2>	1079	=item L<AnyEvent::XMPP>
770		1080
771	AnyEvent based XMPP (Jabber protocol) module family.	1081	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1082	Net::XMPP2>.
		1083
		1084	=item L<AnyEvent::IGS>
		1085
		1086	A non-blocking interface to the Internet Go Server protocol (used by
		1087	L<App::IGS>).
772		1088
773	=item L<Net::FCP>	1089	=item L<Net::FCP>
774		1090
775	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
776	of AnyEvent.	1092	of AnyEvent.
…		…
781		1097
782	=item L<Coro>	1098	=item L<Coro>
783		1099
784	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
785		1101
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>
798
799	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
800
801	=back	1102	=back
802		1103
803	=cut	1104	=cut
804		1105
805	package AnyEvent;	1106	package AnyEvent;
806		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
807	no warnings;	1110	# no warnings
808	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
809		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
810	use Carp;	1118	use Carp ();
811		1119
812	our $VERSION = 4.11;	1120	our $VERSION = '5.0';
813	our $MODEL;	1121	our $MODEL;
814		1122
815	our $AUTOLOAD;	1123	our $AUTOLOAD;
816	our @ISA;	1124	our @ISA;
817		1125
818	our @REGISTRY;	1126	our @REGISTRY;
819		1127
820	our $WIN32;	1128	our $WIN32;
821		1129
		1130	our $VERBOSE;
		1131
822	BEGIN {	1132	BEGIN {
823	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
824	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
825	}
826		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
828		1144
829	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
830		1146
831	{	1147	{
832	my $idx;	1148	my $idx;
…		…
834	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
835	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
836	}	1152	}
837		1153
838	my @models = (	1154	my @models = (
839	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
840	[Event:: => AnyEvent::Impl::Event::],
841	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1156	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
842	# everything below here will not be autoprobed	1157	# everything below here will not (normally) be autoprobed
843	# as the pureperl backend should work everywhere	1158	# as the pureperl backend should work everywhere
844	# and is usually faster	1159	# and is usually faster
		1160	[Event:: => AnyEvent::Impl::Event::, 1],
		1161	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1162	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1163	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
845	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
846	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
850	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
851	[Prima:: => AnyEvent::Impl::POE::],	1168	[Prima:: => AnyEvent::Impl::POE::],
		1169	# IO::Async is just too broken - we would need workarounds for its
		1170	# byzantine signal and broken child handling, among others.
		1171	# IO::Async is rather hard to detect, as it doesn't have any
		1172	# obvious default class.
		1173	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1176	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
852	);	1177	);
853		1178
854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1179	our %method = map +($_ => 1),
		1180	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
855		1181
856	our @post_detect;	1182	our @post_detect;
857		1183
858	sub post_detect(&) {	1184	sub post_detect(&) {
859	my ($cb) = @_;	1185	my ($cb) = @_;
860		1186
861	if ($MODEL) {	1187	if ($MODEL) {
862	$cb->();	1188	$cb->();
863		1189
864	1	1190	undef
865	} else {	1191	} else {
866	push @post_detect, $cb;	1192	push @post_detect, $cb;
867		1193
868	defined wantarray	1194	defined wantarray
869	? bless \$cb, "AnyEvent::Util::PostDetect"	1195	? bless \$cb, "AnyEvent::Util::postdetect"
870	: ()	1196	: ()
871	}	1197	}
872	}	1198	}
873		1199
874	sub AnyEvent::Util::PostDetect::DESTROY {	1200	sub AnyEvent::Util::postdetect::DESTROY {
875	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1201	@post_detect = grep $_ != ${$_[0]}, @post_detect;
876	}	1202	}
877		1203
878	sub detect() {	1204	sub detect() {
879	unless ($MODEL) {	1205	unless ($MODEL) {
880	no strict 'refs';
881	local $SIG{__DIE__};	1206	local $SIG{__DIE__};
882		1207
883	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1208	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
884	my $model = "AnyEvent::Impl::$1";	1209	my $model = "AnyEvent::Impl::$1";
885	if (eval "require $model") {	1210	if (eval "require $model") {
886	$MODEL = $model;	1211	$MODEL = $model;
887	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1212	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
888	} else {	1213	} else {
889	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1214	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
890	}	1215	}
891	}	1216	}
892		1217
893	# check for already loaded models	1218	# check for already loaded models
894	unless ($MODEL) {	1219	unless ($MODEL) {
895	for (@REGISTRY, @models) {	1220	for (@REGISTRY, @models) {
896	my ($package, $model) = @$_;	1221	my ($package, $model) = @$_;
897	if (${"$package\::VERSION"} > 0) {	1222	if (${"$package\::VERSION"} > 0) {
898	if (eval "require $model") {	1223	if (eval "require $model") {
899	$MODEL = $model;	1224	$MODEL = $model;
900	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1225	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
901	last;	1226	last;
902	}	1227	}
903	}	1228	}
904	}	1229	}
905		1230
906	unless ($MODEL) {	1231	unless ($MODEL) {
907	# try to load a model	1232	# try to autoload a model
908
909	for (@REGISTRY, @models) {	1233	for (@REGISTRY, @models) {
910	my ($package, $model) = @$_;	1234	my ($package, $model, $autoload) = @$_;
		1235	if (
		1236	$autoload
911	if (eval "require $package"	1237	and eval "require $package"
912	and ${"$package\::VERSION"} > 0	1238	and ${"$package\::VERSION"} > 0
913	and eval "require $model") {	1239	and eval "require $model"
		1240	) {
914	$MODEL = $model;	1241	$MODEL = $model;
915	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1242	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
916	last;	1243	last;
917	}	1244	}
918	}	1245	}
919		1246
920	$MODEL	1247	$MODEL
921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1248	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
922	}	1249	}
923	}	1250	}
924		1251
		1252	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1253
925	unshift @ISA, $MODEL;	1254	unshift @ISA, $MODEL;
926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1255
		1256	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927		1257
928	(shift @post_detect)->() while @post_detect;	1258	(shift @post_detect)->() while @post_detect;
929	}	1259	}
930		1260
931	$MODEL	1261	$MODEL
…		…
933		1263
934	sub AUTOLOAD {	1264	sub AUTOLOAD {
935	(my $func = $AUTOLOAD) =~ s/.*://;	1265	(my $func = $AUTOLOAD) =~ s/.*://;
936		1266
937	$method{$func}	1267	$method{$func}
938	or croak "$func: not a valid method for AnyEvent objects";	1268	or Carp::croak "$func: not a valid method for AnyEvent objects";
939		1269
940	detect unless $MODEL;	1270	detect unless $MODEL;
941		1271
942	my $class = shift;	1272	my $class = shift;
943	$class->$func (@_);	1273	$class->$func (@_);
944	}	1274	}
945		1275
		1276	# utility function to dup a filehandle. this is used by many backends
		1277	# to support binding more than one watcher per filehandle (they usually
		1278	# allow only one watcher per fd, so we dup it to get a different one).
		1279	sub _dupfh($$;$$) {
		1280	my ($poll, $fh, $r, $w) = @_;
		1281
		1282	# cygwin requires the fh mode to be matching, unix doesn't
		1283	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1284
		1285	open my $fh2, $mode, $fh
		1286	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1287
		1288	# we assume CLOEXEC is already set by perl in all important cases
		1289
		1290	($fh2, $rw)
		1291	}
		1292
		1293	=head1 SIMPLIFIED AE API
		1294
		1295	Starting with version 5.0, AnyEvent officially supports a second, much
		1296	simpler, API that is designed to reduce the calling, typing and memory
		1297	overhead.
		1298
		1299	See the L<AE> manpage for details.
		1300
		1301	=cut
		1302
		1303	package AE;
		1304
		1305	our $VERSION = $AnyEvent::VERSION;
		1306
		1307	sub io($$$) {
		1308	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1309	}
		1310
		1311	sub timer($$$) {
		1312	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1313	}
		1314
		1315	sub signal($$) {
		1316	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1317	}
		1318
		1319	sub child($$) {
		1320	AnyEvent->child (pid => $_[0], cb => $_[1])
		1321	}
		1322
		1323	sub idle($) {
		1324	AnyEvent->idle (cb => $_[0])
		1325	}
		1326
		1327	sub cv(;&) {
		1328	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1329	}
		1330
		1331	sub now() {
		1332	AnyEvent->now
		1333	}
		1334
		1335	sub now_update() {
		1336	AnyEvent->now_update
		1337	}
		1338
		1339	sub time() {
		1340	AnyEvent->time
		1341	}
		1342
946	package AnyEvent::Base;	1343	package AnyEvent::Base;
947		1344
948	# default implementation for now and time	1345	# default implementations for many methods
949		1346
950	use Time::HiRes ();	1347	sub _time {
		1348	# probe for availability of Time::HiRes
		1349	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1350	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1351	*_time = \&Time::HiRes::time;
		1352	# if (eval "use POSIX (); (POSIX::times())...
		1353	} else {
		1354	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1355	*_time = sub { time }; # epic fail
		1356	}
951		1357
952	sub time { Time::HiRes::time }	1358	&_time
953	sub now { Time::HiRes::time }	1359	}
		1360
		1361	sub time { _time }
		1362	sub now { _time }
		1363	sub now_update { }
954		1364
955	# default implementation for ->condvar	1365	# default implementation for ->condvar
956		1366
957	sub condvar {	1367	sub condvar {
958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1368	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
959	}	1369	}
960		1370
961	# default implementation for ->signal	1371	# default implementation for ->signal
962		1372
963	our %SIG_CB;	1373	our $HAVE_ASYNC_INTERRUPT;
		1374
		1375	sub _have_async_interrupt() {
		1376	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1377	&& eval "use Async::Interrupt 1.0 (); 1")
		1378	unless defined $HAVE_ASYNC_INTERRUPT;
		1379
		1380	$HAVE_ASYNC_INTERRUPT
		1381	}
		1382
		1383	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1384	our (%SIG_ASY, %SIG_ASY_W);
		1385	our ($SIG_COUNT, $SIG_TW);
		1386
		1387	sub _signal_exec {
		1388	$HAVE_ASYNC_INTERRUPT
		1389	? $SIGPIPE_R->drain
		1390	: sysread $SIGPIPE_R, my $dummy, 9;
		1391
		1392	while (%SIG_EV) {
		1393	for (keys %SIG_EV) {
		1394	delete $SIG_EV{$_};
		1395	$_->() for values %{ $SIG_CB{$_} || {} };
		1396	}
		1397	}
		1398	}
		1399
		1400	# install a dummy wakeup watcher to reduce signal catching latency
		1401	sub _sig_add() {
		1402	unless ($SIG_COUNT++) {
		1403	# try to align timer on a full-second boundary, if possible
		1404	my $NOW = AE::now;
		1405
		1406	$SIG_TW = AE::timer
		1407	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1408	$MAX_SIGNAL_LATENCY,
		1409	sub { } # just for the PERL_ASYNC_CHECK
		1410	;
		1411	}
		1412	}
		1413
		1414	sub _sig_del {
		1415	undef $SIG_TW
		1416	unless --$SIG_COUNT;
		1417	}
		1418
		1419	our $_sig_name_init; $_sig_name_init = sub {
		1420	eval q{ # poor man's autoloading
		1421	undef $_sig_name_init;
		1422
		1423	if (_have_async_interrupt) {
		1424	*sig2num = \&Async::Interrupt::sig2num;
		1425	*sig2name = \&Async::Interrupt::sig2name;
		1426	} else {
		1427	require Config;
		1428
		1429	my %signame2num;
		1430	@signame2num{ split ' ', $Config::Config{sig_name} }
		1431	= split ' ', $Config::Config{sig_num};
		1432
		1433	my @signum2name;
		1434	@signum2name[values %signame2num] = keys %signame2num;
		1435
		1436	*sig2num = sub($) {
		1437	$_[0] > 0 ? shift : $signame2num{+shift}
		1438	};
		1439	*sig2name = sub ($) {
		1440	$_[0] > 0 ? $signum2name[+shift] : shift
		1441	};
		1442	}
		1443	};
		1444	die if $@;
		1445	};
		1446
		1447	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1448	sub sig2name($) { &$_sig_name_init; &sig2name }
964		1449
965	sub signal {	1450	sub signal {
		1451	eval q{ # poor man's autoloading {}
		1452	# probe for availability of Async::Interrupt
		1453	if (_have_async_interrupt) {
		1454	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1455
		1456	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1457	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1458
		1459	} else {
		1460	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1461
		1462	require Fcntl;
		1463
		1464	if (AnyEvent::WIN32) {
		1465	require AnyEvent::Util;
		1466
		1467	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1468	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1469	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1470	} else {
		1471	pipe $SIGPIPE_R, $SIGPIPE_W;
		1472	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1473	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1474
		1475	# not strictly required, as $^F is normally 2, but let's make sure...
		1476	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1477	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1478	}
		1479
		1480	$SIGPIPE_R
		1481	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1482
		1483	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1484	}
		1485
		1486	*signal = sub {
966	my (undef, %arg) = @_;	1487	my (undef, %arg) = @_;
967		1488
968	my $signal = uc $arg{signal}	1489	my $signal = uc $arg{signal}
969	or Carp::croak "required option 'signal' is missing";	1490	or Carp::croak "required option 'signal' is missing";
970		1491
		1492	if ($HAVE_ASYNC_INTERRUPT) {
		1493	# async::interrupt
		1494
		1495	$signal = sig2num $signal;
971	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1496	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1497
		1498	$SIG_ASY{$signal} ||= new Async::Interrupt
		1499	cb => sub { undef $SIG_EV{$signal} },
		1500	signal => $signal,
		1501	pipe => [$SIGPIPE_R->filenos],
		1502	pipe_autodrain => 0,
		1503	;
		1504
		1505	} else {
		1506	# pure perl
		1507
		1508	# AE::Util has been loaded in signal
		1509	$signal = sig2name $signal;
		1510	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1511
972	$SIG{$signal} ||= sub {	1512	$SIG{$signal} ||= sub {
973	$_->() for values %{ $SIG_CB{$signal} || {} };	1513	local $!;
		1514	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1515	undef $SIG_EV{$signal};
		1516	};
		1517
		1518	# can't do signal processing without introducing races in pure perl,
		1519	# so limit the signal latency.
		1520	_sig_add;
		1521	}
		1522
		1523	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1524	};
		1525
		1526	*AnyEvent::Base::signal::DESTROY = sub {
		1527	my ($signal, $cb) = @{$_[0]};
		1528
		1529	_sig_del;
		1530
		1531	delete $SIG_CB{$signal}{$cb};
		1532
		1533	$HAVE_ASYNC_INTERRUPT
		1534	? delete $SIG_ASY{$signal}
		1535	: # delete doesn't work with older perls - they then
		1536	# print weird messages, or just unconditionally exit
		1537	# instead of getting the default action.
		1538	undef $SIG{$signal}
		1539	unless keys %{ $SIG_CB{$signal} };
		1540	};
974	};	1541	};
975		1542	die if $@;
976	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1543	&signal
977	}
978
979	sub AnyEvent::Base::Signal::DESTROY {
980	my ($signal, $cb) = @{$_[0]};
981
982	delete $SIG_CB{$signal}{$cb};
983
984	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
985	}	1544	}
986		1545
987	# default implementation for ->child	1546	# default implementation for ->child
988		1547
989	our %PID_CB;	1548	our %PID_CB;
990	our $CHLD_W;	1549	our $CHLD_W;
991	our $CHLD_DELAY_W;	1550	our $CHLD_DELAY_W;
992	our $PID_IDLE;
993	our $WNOHANG;	1551	our $WNOHANG;
994		1552
995	sub _child_wait {	1553	sub _emit_childstatus($$) {
996	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1554	my (undef, $rpid, $rstatus) = @_;
		1555
		1556	$_->($rpid, $rstatus)
997	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1557	for values %{ $PID_CB{$rpid} || {} },
998	(values %{ $PID_CB{0} || {} });	1558	values %{ $PID_CB{0} || {} };
999	}
1000
1001	undef $PID_IDLE;
1002	}	1559	}
1003		1560
1004	sub _sigchld {	1561	sub _sigchld {
1005	# make sure we deliver these changes "synchronous" with the event loop.	1562	my $pid;
1006	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1563
1007	undef $CHLD_DELAY_W;	1564	AnyEvent->_emit_childstatus ($pid, $?)
1008	&_child_wait;	1565	while ($pid = waitpid -1, $WNOHANG) > 0;
1009	});
1010	}	1566	}
1011		1567
1012	sub child {	1568	sub child {
1013	my (undef, %arg) = @_;	1569	my (undef, %arg) = @_;
1014		1570
1015	defined (my $pid = $arg{pid} + 0)	1571	defined (my $pid = $arg{pid} + 0)
1016	or Carp::croak "required option 'pid' is missing";	1572	or Carp::croak "required option 'pid' is missing";
1017		1573
1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1574	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1019		1575
1020	unless ($WNOHANG) {	1576	# WNOHANG is almost cetrainly 1 everywhere
		1577	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1578	? 1
1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1579	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1022	}
1023		1580
1024	unless ($CHLD_W) {	1581	unless ($CHLD_W) {
1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1582	$CHLD_W = AE::signal CHLD => \&_sigchld;
1026	# child could be a zombie already, so make at least one round	1583	# child could be a zombie already, so make at least one round
1027	&_sigchld;	1584	&_sigchld;
1028	}	1585	}
1029		1586
1030	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1587	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1031	}	1588	}
1032		1589
1033	sub AnyEvent::Base::Child::DESTROY {	1590	sub AnyEvent::Base::child::DESTROY {
1034	my ($pid, $cb) = @{$_[0]};	1591	my ($pid, $cb) = @{$_[0]};
1035		1592
1036	delete $PID_CB{$pid}{$cb};	1593	delete $PID_CB{$pid}{$cb};
1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1594	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1038		1595
1039	undef $CHLD_W unless keys %PID_CB;	1596	undef $CHLD_W unless keys %PID_CB;
1040	}	1597	}
1041		1598
		1599	# idle emulation is done by simply using a timer, regardless
		1600	# of whether the process is idle or not, and not letting
		1601	# the callback use more than 50% of the time.
		1602	sub idle {
		1603	my (undef, %arg) = @_;
		1604
		1605	my ($cb, $w, $rcb) = $arg{cb};
		1606
		1607	$rcb = sub {
		1608	if ($cb) {
		1609	$w = _time;
		1610	&$cb;
		1611	$w = _time - $w;
		1612
		1613	# never use more then 50% of the time for the idle watcher,
		1614	# within some limits
		1615	$w = 0.0001 if $w < 0.0001;
		1616	$w = 5 if $w > 5;
		1617
		1618	$w = AE::timer $w, 0, $rcb;
		1619	} else {
		1620	# clean up...
		1621	undef $w;
		1622	undef $rcb;
		1623	}
		1624	};
		1625
		1626	$w = AE::timer 0.05, 0, $rcb;
		1627
		1628	bless \\$cb, "AnyEvent::Base::idle"
		1629	}
		1630
		1631	sub AnyEvent::Base::idle::DESTROY {
		1632	undef $${$_[0]};
		1633	}
		1634
1042	package AnyEvent::CondVar;	1635	package AnyEvent::CondVar;
1043		1636
1044	our @ISA = AnyEvent::CondVar::Base::;	1637	our @ISA = AnyEvent::CondVar::Base::;
1045		1638
1046	package AnyEvent::CondVar::Base;	1639	package AnyEvent::CondVar::Base;
1047		1640
1048	use overload	1641	#use overload
1049	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1642	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1050	fallback => 1;	1643	# fallback => 1;
		1644
		1645	# save 300+ kilobytes by dirtily hardcoding overloading
		1646	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1647	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1648	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1649	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1650
		1651	our $WAITING;
1051		1652
1052	sub _send {	1653	sub _send {
1053	# nop	1654	# nop
1054	}	1655	}
1055		1656
…		…
1068	sub ready {	1669	sub ready {
1069	$_[0]{_ae_sent}	1670	$_[0]{_ae_sent}
1070	}	1671	}
1071		1672
1072	sub _wait {	1673	sub _wait {
		1674	$WAITING
		1675	and !$_[0]{_ae_sent}
		1676	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1677
		1678	local $WAITING = 1;
1073	AnyEvent->one_event while !$_[0]{_ae_sent};	1679	AnyEvent->one_event while !$_[0]{_ae_sent};
1074	}	1680	}
1075		1681
1076	sub recv {	1682	sub recv {
1077	$_[0]->_wait;	1683	$_[0]->_wait;
…		…
1079	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1685	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1080	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1686	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1081	}	1687	}
1082		1688
1083	sub cb {	1689	sub cb {
1084	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1690	my $cv = shift;
		1691
		1692	@_
		1693	and $cv->{_ae_cb} = shift
		1694	and $cv->{_ae_sent}
		1695	and (delete $cv->{_ae_cb})->($cv);
		1696
1085	$_[0]{_ae_cb}	1697	$cv->{_ae_cb}
1086	}	1698	}
1087		1699
1088	sub begin {	1700	sub begin {
1089	++$_[0]{_ae_counter};	1701	++$_[0]{_ae_counter};
1090	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1702	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1096	}	1708	}
1097		1709
1098	# undocumented/compatibility with pre-3.4	1710	# undocumented/compatibility with pre-3.4
1099	*broadcast = \&send;	1711	*broadcast = \&send;
1100	*wait = \&_wait;	1712	*wait = \&_wait;
		1713
		1714	=head1 ERROR AND EXCEPTION HANDLING
		1715
		1716	In general, AnyEvent does not do any error handling - it relies on the
		1717	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1718	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1719	checking of all AnyEvent methods, however, which is highly useful during
		1720	development.
		1721
		1722	As for exception handling (i.e. runtime errors and exceptions thrown while
		1723	executing a callback), this is not only highly event-loop specific, but
		1724	also not in any way wrapped by this module, as this is the job of the main
		1725	program.
		1726
		1727	The pure perl event loop simply re-throws the exception (usually
		1728	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1729	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1730	so on.
		1731
		1732	=head1 ENVIRONMENT VARIABLES
		1733
		1734	The following environment variables are used by this module or its
		1735	submodules.
		1736
		1737	Note that AnyEvent will remove I<all> environment variables starting with
		1738	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1739	enabled.
		1740
		1741	=over 4
		1742
		1743	=item C<PERL_ANYEVENT_VERBOSE>
		1744
		1745	By default, AnyEvent will be completely silent except in fatal
		1746	conditions. You can set this environment variable to make AnyEvent more
		1747	talkative.
		1748
		1749	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1750	conditions, such as not being able to load the event model specified by
		1751	C<PERL_ANYEVENT_MODEL>.
		1752
		1753	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1754	model it chooses.
		1755
		1756	When set to C<8> or higher, then AnyEvent will report extra information on
		1757	which optional modules it loads and how it implements certain features.
		1758
		1759	=item C<PERL_ANYEVENT_STRICT>
		1760
		1761	AnyEvent does not do much argument checking by default, as thorough
		1762	argument checking is very costly. Setting this variable to a true value
		1763	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1764	check the arguments passed to most method calls. If it finds any problems,
		1765	it will croak.
		1766
		1767	In other words, enables "strict" mode.
		1768
		1769	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1770	>>, it is definitely recommended to keep it off in production. Keeping
		1771	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1772	can be very useful, however.
		1773
		1774	=item C<PERL_ANYEVENT_MODEL>
		1775
		1776	This can be used to specify the event model to be used by AnyEvent, before
		1777	auto detection and -probing kicks in. It must be a string consisting
		1778	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1779	and the resulting module name is loaded and if the load was successful,
		1780	used as event model. If it fails to load AnyEvent will proceed with
		1781	auto detection and -probing.
		1782
		1783	This functionality might change in future versions.
		1784
		1785	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1786	could start your program like this:
		1787
		1788	PERL_ANYEVENT_MODEL=Perl perl ...
		1789
		1790	=item C<PERL_ANYEVENT_PROTOCOLS>
		1791
		1792	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1793	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1794	of auto probing).
		1795
		1796	Must be set to a comma-separated list of protocols or address families,
		1797	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1798	used, and preference will be given to protocols mentioned earlier in the
		1799	list.
		1800
		1801	This variable can effectively be used for denial-of-service attacks
		1802	against local programs (e.g. when setuid), although the impact is likely
		1803	small, as the program has to handle conenction and other failures anyways.
		1804
		1805	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1806	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1807	- only support IPv4, never try to resolve or contact IPv6
		1808	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1809	IPv6, but prefer IPv6 over IPv4.
		1810
		1811	=item C<PERL_ANYEVENT_EDNS0>
		1812
		1813	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1814	for DNS. This extension is generally useful to reduce DNS traffic, but
		1815	some (broken) firewalls drop such DNS packets, which is why it is off by
		1816	default.
		1817
		1818	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1819	EDNS0 in its DNS requests.
		1820
		1821	=item C<PERL_ANYEVENT_MAX_FORKS>
		1822
		1823	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1824	will create in parallel.
		1825
		1826	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1827
		1828	The default value for the C<max_outstanding> parameter for the default DNS
		1829	resolver - this is the maximum number of parallel DNS requests that are
		1830	sent to the DNS server.
		1831
		1832	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1833
		1834	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1835	configuration) in the default resolver. When set to the empty string, no
		1836	default config will be used.
		1837
		1838	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1839
		1840	When neither C<ca_file> nor C<ca_path> was specified during
		1841	L<AnyEvent::TLS> context creation, and either of these environment
		1842	variables exist, they will be used to specify CA certificate locations
		1843	instead of a system-dependent default.
		1844
		1845	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1846
		1847	When these are set to C<1>, then the respective modules are not
		1848	loaded. Mostly good for testing AnyEvent itself.
		1849
		1850	=back
1101		1851
1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1852	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1103		1853
1104	This is an advanced topic that you do not normally need to use AnyEvent in	1854	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	1855	a module. This section is only of use to event loop authors who want to
…		…
1139		1889
1140	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1890	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1141	condition variables: code blocking while waiting for a condition will	1891	condition variables: code blocking while waiting for a condition will
1142	C<die>. This still works with most modules/usages, and blocking calls must	1892	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.	1893	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		1894
1218	=head1 EXAMPLE PROGRAM	1895	=head1 EXAMPLE PROGRAM
1219		1896
1220	The following program uses an I/O watcher to read data from STDIN, a timer	1897	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	1898	to display a message once per second, and a condition variable to quit the
…		…
1384	through AnyEvent. The benchmark creates a lot of timers (with a zero	2061	through AnyEvent. The benchmark creates a lot of timers (with a zero
1385	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2062	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1386	which it is), lets them fire exactly once and destroys them again.	2063	which it is), lets them fire exactly once and destroys them again.
1387		2064
1388	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2065	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1389	distribution.	2066	distribution. It uses the L<AE> interface, which makes a real difference
		2067	for the EV and Perl backends only.
1390		2068
1391	=head3 Explanation of the columns	2069	=head3 Explanation of the columns
1392		2070
1393	I<watcher> is the number of event watchers created/destroyed. Since	2071	I<watcher> is the number of event watchers created/destroyed. Since
1394	different event models feature vastly different performances, each event	2072	different event models feature vastly different performances, each event
…		…
1415	watcher.	2093	watcher.
1416		2094
1417	=head3 Results	2095	=head3 Results
1418		2096
1419	name watchers bytes create invoke destroy comment	2097	name watchers bytes create invoke destroy comment
1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2098	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2099	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2100	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2101	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2102	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2103	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2104	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2105	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2106	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2107	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2108	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2109	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1430		2110
1431	=head3 Discussion	2111	=head3 Discussion
1432		2112
1433	The benchmark does I<not> measure scalability of the event loop very	2113	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)	2114	well. For example, a select-based event loop (such as the pure perl one)
…		…
1446	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2126	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1447	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2127	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1448	cycles with POE.	2128	cycles with POE.
1449		2129
1450	C<EV> is the sole leader regarding speed and memory use, which are both	2130	C<EV> is the sole leader regarding speed and memory use, which are both
1451	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2131	maximal/minimal, respectively. When using the L<AE> API there is zero
		2132	overhead (when going through the AnyEvent API create is about 5-6 times
		2133	slower, with other times being equal, so still uses far less memory than
1452	far less memory than any other event loop and is still faster than Event	2134	any other event loop and is still faster than Event natively).
1453	natively.
1454		2135
1455	The pure perl implementation is hit in a few sweet spots (both the	2136	The pure perl implementation is hit in a few sweet spots (both the
1456	constant timeout and the use of a single fd hit optimisations in the perl	2137	constant timeout and the use of a single fd hit optimisations in the perl
1457	interpreter and the backend itself). Nevertheless this shows that it	2138	interpreter and the backend itself). Nevertheless this shows that it
1458	adds very little overhead in itself. Like any select-based backend its	2139	adds very little overhead in itself. Like any select-based backend its
1459	performance becomes really bad with lots of file descriptors (and few of	2140	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.	2141	them active), of course, but this was not subject of this benchmark.
1461		2142
1462	The C<Event> module has a relatively high setup and callback invocation	2143	The C<Event> module has a relatively high setup and callback invocation
1463	cost, but overall scores in on the third place.	2144	cost, but overall scores in on the third place.
		2145
		2146	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2147	when using its pure perl backend.
1464		2148
1465	C<Glib>'s memory usage is quite a bit higher, but it features a	2149	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	2150	faster callback invocation and overall ends up in the same class as
1467	C<Event>. However, Glib scales extremely badly, doubling the number of	2151	C<Event>. However, Glib scales extremely badly, doubling the number of
1468	watchers increases the processing time by more than a factor of four,	2152	watchers increases the processing time by more than a factor of four,
…		…
1529	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2213	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1530	(1%) are active. This mirrors the activity of large servers with many	2214	(1%) are active. This mirrors the activity of large servers with many
1531	connections, most of which are idle at any one point in time.	2215	connections, most of which are idle at any one point in time.
1532		2216
1533	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2217	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1534	distribution.	2218	distribution. It uses the L<AE> interface, which makes a real difference
		2219	for the EV and Perl backends only.
1535		2220
1536	=head3 Explanation of the columns	2221	=head3 Explanation of the columns
1537		2222
1538	I<sockets> is the number of sockets, and twice the number of "servers" (as	2223	I<sockets> is the number of sockets, and twice the number of "servers" (as
1539	each server has a read and write socket end).	2224	each server has a read and write socket end).
…		…
1546	it to another server. This includes deleting the old timeout and creating	2231	it to another server. This includes deleting the old timeout and creating
1547	a new one that moves the timeout into the future.	2232	a new one that moves the timeout into the future.
1548		2233
1549	=head3 Results	2234	=head3 Results
1550		2235
1551	name sockets create request	2236	name sockets create request
1552	EV 20000 69.01 11.16	2237	EV 20000 62.66 7.99
1553	Perl 20000 73.32 35.87	2238	Perl 20000 68.32 32.64
1554	Event 20000 212.62 257.32	2239	IOAsync 20000 174.06 101.15 epoll
1555	Glib 20000 651.16 1896.30	2240	IOAsync 20000 174.67 610.84 poll
		2241	Event 20000 202.69 242.91
		2242	Glib 20000 557.01 1689.52
1556	POE 20000 349.67 12317.24 uses POE::Loop::Event	2243	POE 20000 341.54 12086.32 uses POE::Loop::Event
1557		2244
1558	=head3 Discussion	2245	=head3 Discussion
1559		2246
1560	This benchmark I<does> measure scalability and overall performance of the	2247	This benchmark I<does> measure scalability and overall performance of the
1561	particular event loop.	2248	particular event loop.
…		…
1563	EV is again fastest. Since it is using epoll on my system, the setup time	2250	EV is again fastest. Since it is using epoll on my system, the setup time
1564	is relatively high, though.	2251	is relatively high, though.
1565		2252
1566	Perl surprisingly comes second. It is much faster than the C-based event	2253	Perl surprisingly comes second. It is much faster than the C-based event
1567	loops Event and Glib.	2254	loops Event and Glib.
		2255
		2256	IO::Async performs very well when using its epoll backend, and still quite
		2257	good compared to Glib when using its pure perl backend.
1568		2258
1569	Event suffers from high setup time as well (look at its code and you will	2259	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	2260	understand why). Callback invocation also has a high overhead compared to
1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2261	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1572	uses select or poll in basically all documented configurations.	2262	uses select or poll in basically all documented configurations.
…		…
1635	=item * C-based event loops perform very well with small number of	2325	=item * C-based event loops perform very well with small number of
1636	watchers, as the management overhead dominates.	2326	watchers, as the management overhead dominates.
1637		2327
1638	=back	2328	=back
1639		2329
		2330	=head2 THE IO::Lambda BENCHMARK
		2331
		2332	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2333	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2334	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2335	shouldn't come as a surprise to anybody). As such, the benchmark is
		2336	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2337	very optimal. But how would AnyEvent compare when used without the extra
		2338	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2339
		2340	The benchmark itself creates an echo-server, and then, for 500 times,
		2341	connects to the echo server, sends a line, waits for the reply, and then
		2342	creates the next connection. This is a rather bad benchmark, as it doesn't
		2343	test the efficiency of the framework or much non-blocking I/O, but it is a
		2344	benchmark nevertheless.
		2345
		2346	name runtime
		2347	Lambda/select 0.330 sec
		2348	+ optimized 0.122 sec
		2349	Lambda/AnyEvent 0.327 sec
		2350	+ optimized 0.138 sec
		2351	Raw sockets/select 0.077 sec
		2352	POE/select, components 0.662 sec
		2353	POE/select, raw sockets 0.226 sec
		2354	POE/select, optimized 0.404 sec
		2355
		2356	AnyEvent/select/nb 0.085 sec
		2357	AnyEvent/EV/nb 0.068 sec
		2358	+state machine 0.134 sec
		2359
		2360	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2361	benchmarks actually make blocking connects and use 100% blocking I/O,
		2362	defeating the purpose of an event-based solution. All of the newly
		2363	written AnyEvent benchmarks use 100% non-blocking connects (using
		2364	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2365	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2366	generally require a lot more bookkeeping and event handling than blocking
		2367	connects (which involve a single syscall only).
		2368
		2369	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2370	offers similar expressive power as POE and IO::Lambda, using conventional
		2371	Perl syntax. This means that both the echo server and the client are 100%
		2372	non-blocking, further placing it at a disadvantage.
		2373
		2374	As you can see, the AnyEvent + EV combination even beats the
		2375	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2376	backend easily beats IO::Lambda and POE.
		2377
		2378	And even the 100% non-blocking version written using the high-level (and
		2379	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2380	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2381	in a non-blocking way.
		2382
		2383	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2384	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2385	part of the IO::lambda distribution and were used without any changes.
		2386
		2387
		2388	=head1 SIGNALS
		2389
		2390	AnyEvent currently installs handlers for these signals:
		2391
		2392	=over 4
		2393
		2394	=item SIGCHLD
		2395
		2396	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2397	emulation for event loops that do not support them natively. Also, some
		2398	event loops install a similar handler.
		2399
		2400	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2401	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2402
		2403	=item SIGPIPE
		2404
		2405	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2406	when AnyEvent gets loaded.
		2407
		2408	The rationale for this is that AnyEvent users usually do not really depend
		2409	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2410	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2411	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2412	some random socket.
		2413
		2414	The rationale for installing a no-op handler as opposed to ignoring it is
		2415	that this way, the handler will be restored to defaults on exec.
		2416
		2417	Feel free to install your own handler, or reset it to defaults.
		2418
		2419	=back
		2420
		2421	=cut
		2422
		2423	undef $SIG{CHLD}
		2424	if $SIG{CHLD} eq 'IGNORE';
		2425
		2426	$SIG{PIPE} = sub { }
		2427	unless defined $SIG{PIPE};
		2428
		2429	=head1 RECOMMENDED/OPTIONAL MODULES
		2430
		2431	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2432	it's built-in modules) are required to use it.
		2433
		2434	That does not mean that AnyEvent won't take advantage of some additional
		2435	modules if they are installed.
		2436
		2437	This section epxlains which additional modules will be used, and how they
		2438	affect AnyEvent's operetion.
		2439
		2440	=over 4
		2441
		2442	=item L<Async::Interrupt>
		2443
		2444	This slightly arcane module is used to implement fast signal handling: To
		2445	my knowledge, there is no way to do completely race-free and quick
		2446	signal handling in pure perl. To ensure that signals still get
		2447	delivered, AnyEvent will start an interval timer to wake up perl (and
		2448	catch the signals) with some delay (default is 10 seconds, look for
		2449	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2450
		2451	If this module is available, then it will be used to implement signal
		2452	catching, which means that signals will not be delayed, and the event loop
		2453	will not be interrupted regularly, which is more efficient (And good for
		2454	battery life on laptops).
		2455
		2456	This affects not just the pure-perl event loop, but also other event loops
		2457	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2458
		2459	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2460	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2461	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2462	does nothing for those backends.
		2463
		2464	=item L<EV>
		2465
		2466	This module isn't really "optional", as it is simply one of the backend
		2467	event loops that AnyEvent can use. However, it is simply the best event
		2468	loop available in terms of features, speed and stability: It supports
		2469	the AnyEvent API optimally, implements all the watcher types in XS, does
		2470	automatic timer adjustments even when no monotonic clock is available,
		2471	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2472	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2473	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2474
		2475	=item L<Guard>
		2476
		2477	The guard module, when used, will be used to implement
		2478	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2479	lot less memory), but otherwise doesn't affect guard operation much. It is
		2480	purely used for performance.
		2481
		2482	=item L<JSON> and L<JSON::XS>
		2483
		2484	This module is required when you want to read or write JSON data via
		2485	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2486	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2487
		2488	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2489	installed.
		2490
		2491	=item L<Net::SSLeay>
		2492
		2493	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2494	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2495	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2496
		2497	=item L<Time::HiRes>
		2498
		2499	This module is part of perl since release 5.008. It will be used when the
		2500	chosen event library does not come with a timing source on it's own. The
		2501	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2502	try to use a monotonic clock for timing stability.
		2503
		2504	=back
		2505
1640		2506
1641	=head1 FORK	2507	=head1 FORK
1642		2508
1643	Most event libraries are not fork-safe. The ones who are usually are	2509	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>	2510	because they rely on inefficient but fork-safe C<select> or C<poll>
1645	calls. Only L<EV> is fully fork-aware.	2511	calls. Only L<EV> is fully fork-aware.
1646		2512
1647	If you have to fork, you must either do so I<before> creating your first	2513	If you have to fork, you must either do so I<before> creating your first
1648	watcher OR you must not use AnyEvent at all in the child.	2514	watcher OR you must not use AnyEvent at all in the child OR you must do
		2515	something completely out of the scope of AnyEvent.
1649		2516
1650		2517
1651	=head1 SECURITY CONSIDERATIONS	2518	=head1 SECURITY CONSIDERATIONS
1652		2519
1653	AnyEvent can be forced to load any event model via	2520	AnyEvent can be forced to load any event model via
…		…
1658	specified in the variable.	2525	specified in the variable.
1659		2526
1660	You can make AnyEvent completely ignore this variable by deleting it	2527	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:	2528	before the first watcher gets created, e.g. with a C<BEGIN> block:
1662		2529
1663	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2530	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1664		2531
1665	use AnyEvent;	2532	use AnyEvent;
1666		2533
1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2534	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	2535	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).	2536	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2537	$ENV{PERL_ANYEVENT_STRICT}.
		2538
		2539	Note that AnyEvent will remove I<all> environment variables starting with
		2540	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2541	enabled.
		2542
		2543
		2544	=head1 BUGS
		2545
		2546	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2547	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2548	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2549	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2550	pronounced).
1670		2551
1671		2552
1672	=head1 SEE ALSO	2553	=head1 SEE ALSO
1673		2554
1674	Utility functions: L<AnyEvent::Util>.	2555	Utility functions: L<AnyEvent::Util>.
…		…
1677	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2558	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1678		2559
1679	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2560	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1680	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2561	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1681	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2562	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1682	L<AnyEvent::Impl::POE>.	2563	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1683		2564
1684	Non-blocking file handles, sockets, TCP clients and	2565	Non-blocking file handles, sockets, TCP clients and
1685	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2566	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1686		2567
1687	Asynchronous DNS: L<AnyEvent::DNS>.	2568	Asynchronous DNS: L<AnyEvent::DNS>.
1688		2569
1689	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2570	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2571	L<Coro::Event>,
1690		2572
1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2573	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2574	L<AnyEvent::HTTP>.
1692		2575
1693		2576
1694	=head1 AUTHOR	2577	=head1 AUTHOR
1695		2578
1696	Marc Lehmann <schmorp@schmorp.de>	2579	Marc Lehmann <schmorp@schmorp.de>
1697	http://home.schmorp.de/	2580	http://home.schmorp.de/
1698		2581
1699	=cut	2582	=cut
1700		2583
1701	1	2584	1
1702		2585

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