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Revision 1.144 by root, Thu May 29 00:14:35 2008 UTC vs.
Revision 1.276 by root, Sun Aug 9 10:53:33 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 });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
		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.
22		53
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		55
25	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
26	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
27		58
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
30		61
31	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
32	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
33	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	65	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	66	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
37		69
38	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
39	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
40	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
42	model you use.	74	model you use.
43		75
44	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
45	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
46	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
47	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	80	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	81	module are I<also> forced to use the same event loop you use.
50		82
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	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
53	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
54	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,
55	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
56	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
57	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
58	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
59		91
60	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
61	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
62	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
63	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
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	156	is in control).
125		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
126	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
127	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
128	to it).	166	to it).
129		167
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	170	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		172
135	An any way to achieve that is this pattern:	173	An any way to achieve that is this pattern:
136		174
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	175	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	176	# you can use $w here, for example to undef it
139	undef $w;	177	undef $w;
140	});	178	});
141		179
142	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,
143	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
144	declared.	182	declared.
145		183
146	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
147		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
148	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
149	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
150		194
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
154	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.
155	becomes ready.
156		206
157	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
160		210
…		…
164		214
165	Some event loops issue spurious readyness notifications, so you should	215	Some event loops issue spurious readyness notifications, so you should
166	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
167	handles.	217	handles.
168		218
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	222	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	223	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	224	warn "read: $input\n";
175	undef $w;	225	undef $w;
176	});	226	});
177		227
178	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
179		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
180	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 >>
181	method with the following mandatory arguments:	239	method with the following mandatory arguments:
182		240
183	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
184	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
…		…
186		244
187	Although the callback might get passed parameters, their value and	245	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	246	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	247	callbacks cannot use arguments passed to time watcher callbacks.
190		248
191	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
192	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
193	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.
194		254
195	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.
196		258
197	# fire an event after 7.7 seconds	259	Example: fire an event after 7.7 seconds.
		260
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	261	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	262	warn "timeout\n";
200	});	263	});
201		264
202	# to cancel the timer:	265	# to cancel the timer:
203	undef $w;	266	undef $w;
204		267
205	Example 2:
206
207	# 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.
208	my $w;
209		269
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	270	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		271	warn "timeout\n";
213	};	272	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		273
218	=head3 TIMING ISSUES	274	=head3 TIMING ISSUES
219		275
220	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
221	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
…		…
294	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
295	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
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	353	account.
298		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
299	=back	370	=back
300		371
301	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
302		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
303	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
304	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
305	be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
306		379
307	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	381	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	382	callbacks cannot use arguments passed to signal watcher callbacks.
310		383
…		…
312	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
313	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,
314	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
315		388
316	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
317	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
318		392
319	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
320	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
321		396
322	Example: exit on SIGINT	397	Example: exit on SIGINT
323		398
324	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
325		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$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
326	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
327		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
328	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.
329		426
330	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,
331	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
332	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
333	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
334	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
335	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).
336		441
337	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
338	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
339	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
340		445
341	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
342	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
343	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.
344		452
345	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
346	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
347	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.
348		461
349	Example: fork a process and wait for it	462	Example: fork a process and wait for it
350		463
351	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
352		465
353	my $pid = fork or exit 5;	466	my $pid = fork or exit 5;
354		467
355	my $w = AnyEvent->child (	468	my $w = AnyEvent->child (
356	pid => $pid,	469	pid => $pid,
357	cb => sub {	470	cb => sub {
358	my ($pid, $status) = @_;	471	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	472	warn "pid $pid exited with status $status";
360	$done->send;	473	$done->send;
361	},	474	},
362	);	475	);
363		476
364	# do something else, then wait for process exit	477	# do something else, then wait for process exit
365	$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	});
366		516
367	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
368		523
369	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
370	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
371	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
372		527
373	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
374	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).
375		530
376	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
377	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.
378		535
379	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
381	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
382	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
383		541
384	After creation, the condition variable is "false" until it becomes "true"	542	After creation, the condition variable is "false" until it becomes "true"
385	by calling the C<send> method (or calling the condition variable as if it	543	by calling the C<send> method (or calling the condition variable as if it
386	were a callback, read about the caveats in the description for the C<<	544	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	545	->send >> method).
…		…
389	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
390	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
391	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
392	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
393	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
394	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.
395		554
396	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
397	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,
398	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
399	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
…		…
433	after => 1,	592	after => 1,
434	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
435	);	594	);
436		595
437	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
438	# calls send	597	# calls -<send
439	$result_ready->recv;	598	$result_ready->recv;
440		599
441	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
442	condition variables are also code references.	601	variables are also callable directly.
443		602
444	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$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	});
447		623
448	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
449		625
450	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
451	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
…		…
464	immediately from within send.	640	immediately from within send.
465		641
466	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
467	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
468		644
469	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
470	(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
471	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
472	overloading, so as tempting as it may be, passing a condition variable
473	instead of a callback does not work. Both the pure perl and EV loops
474	support overloading, however, as well as all functions that use perl to
475	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
476	example).
477		648
478	=item $cv->croak ($error)	649	=item $cv->croak ($error)
479		650
480	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
481	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
482		653
483	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
484	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.
485		660
486	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
487		662
488	=item $cv->end	663	=item $cv->end
489
490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
491		664
492	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
493	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
494	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
495		668
…		…
497	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
498	>>, 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
499	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
500	callback was set, C<send> will be called without any arguments.	673	callback was set, C<send> will be called without any arguments.
501		674
502	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:
503		706
504	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
505		708
506	my %result;	709	my %result;
507	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
527	loop, which serves two important purposes: first, it sets the callback	730	loop, which serves two important purposes: first, it sets the callback
528	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
529	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
530	doesn't execute once).	733	doesn't execute once).
531		734
532	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
533	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
534	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
535	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>.
536		740
537	=back	741	=back
538		742
539	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
540		744
…		…
556	function will call C<croak>.	760	function will call C<croak>.
557		761
558	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,
559	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
560		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
561	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
562	(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
563	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
564	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
565	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
566	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,
567	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
568		779
569	Another reason I<never> to C<< ->recv >> in a module is that you cannot
570	sensibly have two C<< ->recv >>'s in parallel, as that would require
571	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
572	can supply.
573
574	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
575	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
576	versions and also integrates coroutines into AnyEvent, making blocking
577	C<< ->recv >> calls perfectly safe as long as they are done from another
578	coroutine (one that doesn't run the event loop).
579
580	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
581	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
582	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
583	waits otherwise.	783	waits otherwise.
584		784
585	=item $bool = $cv->ready	785	=item $bool = $cv->ready
586		786
587	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
588	C<croak> have been called.	788	C<croak> have been called.
589		789
590	=item $cb = $cv->cb ([new callback])	790	=item $cb = $cv->cb ($cb->($cv))
591		791
592	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
593	replaces it before doing so.	793	replaces it before doing so.
594		794
595	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)
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	796	"true", i.e. when C<send> or C<croak> are called (or were called), with
		797	the only argument being the condition variable itself. Calling C<recv>
597	or at any later time is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
598		799
599	=back	800	=back
600		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
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
603	=over 4	875	=over 4
604		876
605	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
606		878
607	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
608	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
609	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
612		886	will be C<urxvt::anyevent>).
613	The known classes so far are:
614
615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
616	AnyEvent::Impl::Event based on Event, second best choice.
617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
618	AnyEvent::Impl::Glib based on Glib, third-best choice.
619	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623
624	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
629	it's adaptor.
630
631	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
632	autodetecting them.
633		887
634	=item AnyEvent::detect	888	=item AnyEvent::detect
635		889
636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
637	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
638	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
639	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>.
640		897
641	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
642		899
643	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
644	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
645		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$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
646	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
647	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
648	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 ||= $guard;
649		934
650	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
651		936
652	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
653	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
654	the event loop has been chosen.	939	the event loop has been chosen.
655		940
656	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	You should check C<$AnyEvent::MODEL> before adding to this array, though:
657	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
658	and the array will be ignored.	943	array will be ignored.
659		944
660	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.
661		952
662	=back	953	=back
663		954
664	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
665		956
…		…
720		1011
721		1012
722	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
723		1014
724	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
725	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
726	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
727	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
728		1019
729	=over 4	1020	=over 4
730		1021
731	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
732		1023
733	Contains various utility functions that replace often-used but blocking	1024	Contains various utility functions that replace often-used but blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	1025	functions such as C<inet_aton> by event-/callback-based versions.
735
736	=item L<AnyEvent::Handle>
737
738	Provide read and write buffers and manages watchers for reads and writes.
739		1026
740	=item L<AnyEvent::Socket>	1027	=item L<AnyEvent::Socket>
741		1028
742	Provides various utility functions for (internet protocol) sockets,	1029	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	1030	addresses and name resolution. Also functions to create non-blocking tcp
744	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.
745		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
746	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
747		1040
748	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
749		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
750	=item L<AnyEvent::HTTPD>	1048	=item L<AnyEvent::HTTPD>
751		1049
752	Provides a simple web application server framework.	1050	Provides a simple web application server framework.
753		1051
754	=item L<AnyEvent::FastPing>	1052	=item L<AnyEvent::FastPing>
755		1053
756	The fastest ping in the west.	1054	The fastest ping in the west.
757		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
758	=item L<Net::IRC3>	1075	=item L<AnyEvent::IRC>
759		1076
760	AnyEvent based IRC client module family.	1077	AnyEvent based IRC client module family (replacing the older Net::IRC3).
761		1078
762	=item L<Net::XMPP2>	1079	=item L<AnyEvent::XMPP>
763		1080
764	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>).
765		1088
766	=item L<Net::FCP>	1089	=item L<Net::FCP>
767		1090
768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
769	of AnyEvent.	1092	of AnyEvent.
…		…
774		1097
775	=item L<Coro>	1098	=item L<Coro>
776		1099
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
778		1101
779	=item L<AnyEvent::AIO>, L<IO::AIO>
780
781	Truly asynchronous I/O, should be in the toolbox of every event
782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
783	together.
784
785	=item L<AnyEvent::BDB>, L<BDB>
786
787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
788	IO::AIO and AnyEvent together.
789
790	=item L<IO::Lambda>
791
792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793
794	=back	1102	=back
795		1103
796	=cut	1104	=cut
797		1105
798	package AnyEvent;	1106	package AnyEvent;
799		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
800	no warnings;	1110	# no warnings
801	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
802		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
803	use Carp;	1118	use Carp ();
804		1119
805	our $VERSION = '4.05';	1120	our $VERSION = 4.92;
806	our $MODEL;	1121	our $MODEL;
807		1122
808	our $AUTOLOAD;	1123	our $AUTOLOAD;
809	our @ISA;	1124	our @ISA;
810		1125
811	our @REGISTRY;	1126	our @REGISTRY;
812		1127
813	our $WIN32;	1128	our $WIN32;
814		1129
		1130	our $VERBOSE;
		1131
815	BEGIN {	1132	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
817	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
818	}
819		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
821		1144
822	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
823		1146
824	{	1147	{
825	my $idx;	1148	my $idx;
…		…
827	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
828	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
829	}	1152	}
830		1153
831	my @models = (	1154	my @models = (
832	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
833	[Event:: => AnyEvent::Impl::Event::],
834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1156	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
835	# everything below here will not be autoprobed	1157	# everything below here will not (normally) be autoprobed
836	# as the pureperl backend should work everywhere	1158	# as the pureperl backend should work everywhere
837	# 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
838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
844	[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	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
845	);	1176	);
846		1177
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1178	our %method = map +($_ => 1),
		1179	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
848		1180
849	our @post_detect;	1181	our @post_detect;
850		1182
851	sub post_detect(&) {	1183	sub post_detect(&) {
852	my ($cb) = @_;	1184	my ($cb) = @_;
853		1185
854	if ($MODEL) {	1186	if ($MODEL) {
855	$cb->();	1187	$cb->();
856		1188
857	1	1189	undef
858	} else {	1190	} else {
859	push @post_detect, $cb;	1191	push @post_detect, $cb;
860		1192
861	defined wantarray	1193	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"	1194	? bless \$cb, "AnyEvent::Util::postdetect"
863	: ()	1195	: ()
864	}	1196	}
865	}	1197	}
866		1198
867	sub AnyEvent::Util::PostDetect::DESTROY {	1199	sub AnyEvent::Util::postdetect::DESTROY {
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1200	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}	1201	}
870		1202
871	sub detect() {	1203	sub detect() {
872	unless ($MODEL) {	1204	unless ($MODEL) {
873	no strict 'refs';
874	local $SIG{__DIE__};	1205	local $SIG{__DIE__};
875		1206
876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1207	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
877	my $model = "AnyEvent::Impl::$1";	1208	my $model = "AnyEvent::Impl::$1";
878	if (eval "require $model") {	1209	if (eval "require $model") {
879	$MODEL = $model;	1210	$MODEL = $model;
880	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1211	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
881	} else {	1212	} else {
882	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1213	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
883	}	1214	}
884	}	1215	}
885		1216
886	# check for already loaded models	1217	# check for already loaded models
887	unless ($MODEL) {	1218	unless ($MODEL) {
888	for (@REGISTRY, @models) {	1219	for (@REGISTRY, @models) {
889	my ($package, $model) = @$_;	1220	my ($package, $model) = @$_;
890	if (${"$package\::VERSION"} > 0) {	1221	if (${"$package\::VERSION"} > 0) {
891	if (eval "require $model") {	1222	if (eval "require $model") {
892	$MODEL = $model;	1223	$MODEL = $model;
893	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1224	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
894	last;	1225	last;
895	}	1226	}
896	}	1227	}
897	}	1228	}
898		1229
899	unless ($MODEL) {	1230	unless ($MODEL) {
900	# try to load a model	1231	# try to autoload a model
901
902	for (@REGISTRY, @models) {	1232	for (@REGISTRY, @models) {
903	my ($package, $model) = @$_;	1233	my ($package, $model, $autoload) = @$_;
		1234	if (
		1235	$autoload
904	if (eval "require $package"	1236	and eval "require $package"
905	and ${"$package\::VERSION"} > 0	1237	and ${"$package\::VERSION"} > 0
906	and eval "require $model") {	1238	and eval "require $model"
		1239	) {
907	$MODEL = $model;	1240	$MODEL = $model;
908	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1241	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
909	last;	1242	last;
910	}	1243	}
911	}	1244	}
912		1245
913	$MODEL	1246	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1247	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
915	}	1248	}
916	}	1249	}
917		1250
		1251	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1252
918	unshift @ISA, $MODEL;	1253	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1254
		1255	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
920		1256
921	(shift @post_detect)->() while @post_detect;	1257	(shift @post_detect)->() while @post_detect;
922	}	1258	}
923		1259
924	$MODEL	1260	$MODEL
…		…
926		1262
927	sub AUTOLOAD {	1263	sub AUTOLOAD {
928	(my $func = $AUTOLOAD) =~ s/.*://;	1264	(my $func = $AUTOLOAD) =~ s/.*://;
929		1265
930	$method{$func}	1266	$method{$func}
931	or croak "$func: not a valid method for AnyEvent objects";	1267	or Carp::croak "$func: not a valid method for AnyEvent objects";
932		1268
933	detect unless $MODEL;	1269	detect unless $MODEL;
934		1270
935	my $class = shift;	1271	my $class = shift;
936	$class->$func (@_);	1272	$class->$func (@_);
937	}	1273	}
938		1274
		1275	# utility function to dup a filehandle. this is used by many backends
		1276	# to support binding more than one watcher per filehandle (they usually
		1277	# allow only one watcher per fd, so we dup it to get a different one).
		1278	sub _dupfh($$;$$) {
		1279	my ($poll, $fh, $r, $w) = @_;
		1280
		1281	# cygwin requires the fh mode to be matching, unix doesn't
		1282	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1283
		1284	open my $fh2, $mode, $fh
		1285	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1286
		1287	# we assume CLOEXEC is already set by perl in all important cases
		1288
		1289	($fh2, $rw)
		1290	}
		1291
		1292	#############################################################################
		1293	# "new" API, currently only emulation of it
		1294	#############################################################################
		1295
		1296	package AE;
		1297
		1298	our $VERSION = $AnyEvent::VERSION;
		1299
		1300	sub io($$$) {
		1301	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1302	}
		1303
		1304	sub timer($$$) {
		1305	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1306	}
		1307
		1308	sub signal($$) {
		1309	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1310	}
		1311
		1312	sub child($$) {
		1313	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1314	}
		1315
		1316	sub idle($) {
		1317	AnyEvent->idle (cb => $_[0]);
		1318	}
		1319
		1320	sub cv(;&) {
		1321	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1322	}
		1323
		1324	sub now() {
		1325	AnyEvent->now
		1326	}
		1327
		1328	sub now_update() {
		1329	AnyEvent->now_update
		1330	}
		1331
		1332	sub time() {
		1333	AnyEvent->time
		1334	}
		1335
939	package AnyEvent::Base;	1336	package AnyEvent::Base;
940		1337
941	# default implementation for now and time	1338	# default implementations for many methods
942		1339
943	use Time::HiRes ();	1340	sub _time {
		1341	# probe for availability of Time::HiRes
		1342	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1343	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1344	*_time = \&Time::HiRes::time;
		1345	# if (eval "use POSIX (); (POSIX::times())...
		1346	} else {
		1347	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1348	*_time = sub { time }; # epic fail
		1349	}
944		1350
945	sub time { Time::HiRes::time }	1351	&_time
946	sub now { Time::HiRes::time }	1352	}
		1353
		1354	sub time { _time }
		1355	sub now { _time }
		1356	sub now_update { }
947		1357
948	# default implementation for ->condvar	1358	# default implementation for ->condvar
949		1359
950	sub condvar {	1360	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1361	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
952	}	1362	}
953		1363
954	# default implementation for ->signal	1364	# default implementation for ->signal
955		1365
956	our %SIG_CB;	1366	our $HAVE_ASYNC_INTERRUPT;
		1367
		1368	sub _have_async_interrupt() {
		1369	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1370	&& eval "use Async::Interrupt 1.0 (); 1")
		1371	unless defined $HAVE_ASYNC_INTERRUPT;
		1372
		1373	$HAVE_ASYNC_INTERRUPT
		1374	}
		1375
		1376	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1377	our (%SIG_ASY, %SIG_ASY_W);
		1378	our ($SIG_COUNT, $SIG_TW);
		1379
		1380	sub _signal_exec {
		1381	$HAVE_ASYNC_INTERRUPT
		1382	? $SIGPIPE_R->drain
		1383	: sysread $SIGPIPE_R, my $dummy, 9;
		1384
		1385	while (%SIG_EV) {
		1386	for (keys %SIG_EV) {
		1387	delete $SIG_EV{$_};
		1388	$_->() for values %{ $SIG_CB{$_} || {} };
		1389	}
		1390	}
		1391	}
		1392
		1393	# install a dummy wakeup watcher to reduce signal catching latency
		1394	sub _sig_add() {
		1395	unless ($SIG_COUNT++) {
		1396	# try to align timer on a full-second boundary, if possible
		1397	my $NOW = AE::now;
		1398
		1399	$SIG_TW = AE::timer
		1400	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1401	$MAX_SIGNAL_LATENCY,
		1402	sub { } # just for the PERL_ASYNC_CHECK
		1403	;
		1404	}
		1405	}
		1406
		1407	sub _sig_del {
		1408	undef $SIG_TW
		1409	unless --$SIG_COUNT;
		1410	}
		1411
		1412	our $_sig_name_init; $_sig_name_init = sub {
		1413	eval q{ # poor man's autoloading
		1414	undef $_sig_name_init;
		1415
		1416	if (_have_async_interrupt) {
		1417	*sig2num = \&Async::Interrupt::sig2num;
		1418	*sig2name = \&Async::Interrupt::sig2name;
		1419	} else {
		1420	require Config;
		1421
		1422	my %signame2num;
		1423	@signame2num{ split ' ', $Config::Config{sig_name} }
		1424	= split ' ', $Config::Config{sig_num};
		1425
		1426	my @signum2name;
		1427	@signum2name[values %signame2num] = keys %signame2num;
		1428
		1429	*sig2num = sub($) {
		1430	$_[0] > 0 ? shift : $signame2num{+shift}
		1431	};
		1432	*sig2name = sub ($) {
		1433	$_[0] > 0 ? $signum2name[+shift] : shift
		1434	};
		1435	}
		1436	};
		1437	die if $@;
		1438	};
		1439
		1440	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1441	sub sig2name($) { &$_sig_name_init; &sig2name }
957		1442
958	sub signal {	1443	sub signal {
		1444	eval q{ # poor man's autoloading {}
		1445	# probe for availability of Async::Interrupt
		1446	if (_have_async_interrupt) {
		1447	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1448
		1449	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1450	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1451
		1452	} else {
		1453	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1454
		1455	require Fcntl;
		1456
		1457	if (AnyEvent::WIN32) {
		1458	require AnyEvent::Util;
		1459
		1460	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1461	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1462	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1463	} else {
		1464	pipe $SIGPIPE_R, $SIGPIPE_W;
		1465	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1466	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1467
		1468	# not strictly required, as $^F is normally 2, but let's make sure...
		1469	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1470	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1471	}
		1472
		1473	$SIGPIPE_R
		1474	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1475
		1476	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1477	}
		1478
		1479	*signal = sub {
959	my (undef, %arg) = @_;	1480	my (undef, %arg) = @_;
960		1481
961	my $signal = uc $arg{signal}	1482	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";	1483	or Carp::croak "required option 'signal' is missing";
963		1484
		1485	if ($HAVE_ASYNC_INTERRUPT) {
		1486	# async::interrupt
		1487
		1488	$signal = sig2num $signal;
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1489	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1490
		1491	$SIG_ASY{$signal} ||= new Async::Interrupt
		1492	cb => sub { undef $SIG_EV{$signal} },
		1493	signal => $signal,
		1494	pipe => [$SIGPIPE_R->filenos],
		1495	pipe_autodrain => 0,
		1496	;
		1497
		1498	} else {
		1499	# pure perl
		1500
		1501	# AE::Util has been loaded in signal
		1502	$signal = sig2name $signal;
		1503	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1504
965	$SIG{$signal} ||= sub {	1505	$SIG{$signal} ||= sub {
966	$_->() for values %{ $SIG_CB{$signal} || {} };	1506	local $!;
		1507	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1508	undef $SIG_EV{$signal};
		1509	};
		1510
		1511	# can't do signal processing without introducing races in pure perl,
		1512	# so limit the signal latency.
		1513	_sig_add;
		1514	}
		1515
		1516	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1517	};
		1518
		1519	*AnyEvent::Base::signal::DESTROY = sub {
		1520	my ($signal, $cb) = @{$_[0]};
		1521
		1522	_sig_del;
		1523
		1524	delete $SIG_CB{$signal}{$cb};
		1525
		1526	$HAVE_ASYNC_INTERRUPT
		1527	? delete $SIG_ASY{$signal}
		1528	: # delete doesn't work with older perls - they then
		1529	# print weird messages, or just unconditionally exit
		1530	# instead of getting the default action.
		1531	undef $SIG{$signal}
		1532	unless keys %{ $SIG_CB{$signal} };
		1533	};
967	};	1534	};
968		1535	die if $@;
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1536	&signal
970	}
971
972	sub AnyEvent::Base::Signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};
974
975	delete $SIG_CB{$signal}{$cb};
976
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
978	}	1537	}
979		1538
980	# default implementation for ->child	1539	# default implementation for ->child
981		1540
982	our %PID_CB;	1541	our %PID_CB;
983	our $CHLD_W;	1542	our $CHLD_W;
984	our $CHLD_DELAY_W;	1543	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;	1544	our $WNOHANG;
987		1545
988	sub _child_wait {	1546	sub _emit_childstatus($$) {
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1547	my (undef, $rpid, $rstatus) = @_;
		1548
		1549	$_->($rpid, $rstatus)
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1550	for values %{ $PID_CB{$rpid} || {} },
991	(values %{ $PID_CB{0} || {} });	1551	values %{ $PID_CB{0} || {} };
992	}
993
994	undef $PID_IDLE;
995	}	1552	}
996		1553
997	sub _sigchld {	1554	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.	1555	my $pid;
999	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1556
1000	undef $CHLD_DELAY_W;	1557	AnyEvent->_emit_childstatus ($pid, $?)
1001	&_child_wait;	1558	while ($pid = waitpid -1, $WNOHANG) > 0;
1002	});
1003	}	1559	}
1004		1560
1005	sub child {	1561	sub child {
1006	my (undef, %arg) = @_;	1562	my (undef, %arg) = @_;
1007		1563
1008	defined (my $pid = $arg{pid} + 0)	1564	defined (my $pid = $arg{pid} + 0)
1009	or Carp::croak "required option 'pid' is missing";	1565	or Carp::croak "required option 'pid' is missing";
1010		1566
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1567	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1012		1568
1013	unless ($WNOHANG) {	1569	# WNOHANG is almost cetrainly 1 everywhere
		1570	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1571	? 1
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1572	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015	}
1016		1573
1017	unless ($CHLD_W) {	1574	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1575	$CHLD_W = AE::signal CHLD => \&_sigchld;
1019	# child could be a zombie already, so make at least one round	1576	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1577	&_sigchld;
1021	}	1578	}
1022		1579
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1580	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1024	}	1581	}
1025		1582
1026	sub AnyEvent::Base::Child::DESTROY {	1583	sub AnyEvent::Base::child::DESTROY {
1027	my ($pid, $cb) = @{$_[0]};	1584	my ($pid, $cb) = @{$_[0]};
1028		1585
1029	delete $PID_CB{$pid}{$cb};	1586	delete $PID_CB{$pid}{$cb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1587	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1588
1032	undef $CHLD_W unless keys %PID_CB;	1589	undef $CHLD_W unless keys %PID_CB;
1033	}	1590	}
1034		1591
		1592	# idle emulation is done by simply using a timer, regardless
		1593	# of whether the process is idle or not, and not letting
		1594	# the callback use more than 50% of the time.
		1595	sub idle {
		1596	my (undef, %arg) = @_;
		1597
		1598	my ($cb, $w, $rcb) = $arg{cb};
		1599
		1600	$rcb = sub {
		1601	if ($cb) {
		1602	$w = _time;
		1603	&$cb;
		1604	$w = _time - $w;
		1605
		1606	# never use more then 50% of the time for the idle watcher,
		1607	# within some limits
		1608	$w = 0.0001 if $w < 0.0001;
		1609	$w = 5 if $w > 5;
		1610
		1611	$w = AE::timer $w, 0, $rcb;
		1612	} else {
		1613	# clean up...
		1614	undef $w;
		1615	undef $rcb;
		1616	}
		1617	};
		1618
		1619	$w = AE::timer 0.05, 0, $rcb;
		1620
		1621	bless \\$cb, "AnyEvent::Base::idle"
		1622	}
		1623
		1624	sub AnyEvent::Base::idle::DESTROY {
		1625	undef $${$_[0]};
		1626	}
		1627
1035	package AnyEvent::CondVar;	1628	package AnyEvent::CondVar;
1036		1629
1037	our @ISA = AnyEvent::CondVar::Base::;	1630	our @ISA = AnyEvent::CondVar::Base::;
1038		1631
1039	package AnyEvent::CondVar::Base;	1632	package AnyEvent::CondVar::Base;
1040		1633
1041	use overload	1634	#use overload
1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1635	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1043	fallback => 1;	1636	# fallback => 1;
		1637
		1638	# save 300+ kilobytes by dirtily hardcoding overloading
		1639	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1640	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1641	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1642	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1643
		1644	our $WAITING;
1044		1645
1045	sub _send {	1646	sub _send {
1046	# nop	1647	# nop
1047	}	1648	}
1048		1649
…		…
1061	sub ready {	1662	sub ready {
1062	$_[0]{_ae_sent}	1663	$_[0]{_ae_sent}
1063	}	1664	}
1064		1665
1065	sub _wait {	1666	sub _wait {
		1667	$WAITING
		1668	and !$_[0]{_ae_sent}
		1669	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1670
		1671	local $WAITING = 1;
1066	AnyEvent->one_event while !$_[0]{_ae_sent};	1672	AnyEvent->one_event while !$_[0]{_ae_sent};
1067	}	1673	}
1068		1674
1069	sub recv {	1675	sub recv {
1070	$_[0]->_wait;	1676	$_[0]->_wait;
…		…
1072	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1678	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1073	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1679	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1074	}	1680	}
1075		1681
1076	sub cb {	1682	sub cb {
1077	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1683	my $cv = shift;
		1684
		1685	@_
		1686	and $cv->{_ae_cb} = shift
		1687	and $cv->{_ae_sent}
		1688	and (delete $cv->{_ae_cb})->($cv);
		1689
1078	$_[0]{_ae_cb}	1690	$cv->{_ae_cb}
1079	}	1691	}
1080		1692
1081	sub begin {	1693	sub begin {
1082	++$_[0]{_ae_counter};	1694	++$_[0]{_ae_counter};
1083	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1695	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1089	}	1701	}
1090		1702
1091	# undocumented/compatibility with pre-3.4	1703	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	1704	*broadcast = \&send;
1093	*wait = \&_wait;	1705	*wait = \&_wait;
		1706
		1707	=head1 ERROR AND EXCEPTION HANDLING
		1708
		1709	In general, AnyEvent does not do any error handling - it relies on the
		1710	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1711	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1712	checking of all AnyEvent methods, however, which is highly useful during
		1713	development.
		1714
		1715	As for exception handling (i.e. runtime errors and exceptions thrown while
		1716	executing a callback), this is not only highly event-loop specific, but
		1717	also not in any way wrapped by this module, as this is the job of the main
		1718	program.
		1719
		1720	The pure perl event loop simply re-throws the exception (usually
		1721	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1722	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1723	so on.
		1724
		1725	=head1 ENVIRONMENT VARIABLES
		1726
		1727	The following environment variables are used by this module or its
		1728	submodules.
		1729
		1730	Note that AnyEvent will remove I<all> environment variables starting with
		1731	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1732	enabled.
		1733
		1734	=over 4
		1735
		1736	=item C<PERL_ANYEVENT_VERBOSE>
		1737
		1738	By default, AnyEvent will be completely silent except in fatal
		1739	conditions. You can set this environment variable to make AnyEvent more
		1740	talkative.
		1741
		1742	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1743	conditions, such as not being able to load the event model specified by
		1744	C<PERL_ANYEVENT_MODEL>.
		1745
		1746	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1747	model it chooses.
		1748
		1749	When set to C<8> or higher, then AnyEvent will report extra information on
		1750	which optional modules it loads and how it implements certain features.
		1751
		1752	=item C<PERL_ANYEVENT_STRICT>
		1753
		1754	AnyEvent does not do much argument checking by default, as thorough
		1755	argument checking is very costly. Setting this variable to a true value
		1756	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1757	check the arguments passed to most method calls. If it finds any problems,
		1758	it will croak.
		1759
		1760	In other words, enables "strict" mode.
		1761
		1762	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1763	>>, it is definitely recommended to keep it off in production. Keeping
		1764	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1765	can be very useful, however.
		1766
		1767	=item C<PERL_ANYEVENT_MODEL>
		1768
		1769	This can be used to specify the event model to be used by AnyEvent, before
		1770	auto detection and -probing kicks in. It must be a string consisting
		1771	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1772	and the resulting module name is loaded and if the load was successful,
		1773	used as event model. If it fails to load AnyEvent will proceed with
		1774	auto detection and -probing.
		1775
		1776	This functionality might change in future versions.
		1777
		1778	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1779	could start your program like this:
		1780
		1781	PERL_ANYEVENT_MODEL=Perl perl ...
		1782
		1783	=item C<PERL_ANYEVENT_PROTOCOLS>
		1784
		1785	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1786	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1787	of auto probing).
		1788
		1789	Must be set to a comma-separated list of protocols or address families,
		1790	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1791	used, and preference will be given to protocols mentioned earlier in the
		1792	list.
		1793
		1794	This variable can effectively be used for denial-of-service attacks
		1795	against local programs (e.g. when setuid), although the impact is likely
		1796	small, as the program has to handle conenction and other failures anyways.
		1797
		1798	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1799	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1800	- only support IPv4, never try to resolve or contact IPv6
		1801	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1802	IPv6, but prefer IPv6 over IPv4.
		1803
		1804	=item C<PERL_ANYEVENT_EDNS0>
		1805
		1806	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1807	for DNS. This extension is generally useful to reduce DNS traffic, but
		1808	some (broken) firewalls drop such DNS packets, which is why it is off by
		1809	default.
		1810
		1811	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1812	EDNS0 in its DNS requests.
		1813
		1814	=item C<PERL_ANYEVENT_MAX_FORKS>
		1815
		1816	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1817	will create in parallel.
		1818
		1819	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1820
		1821	The default value for the C<max_outstanding> parameter for the default DNS
		1822	resolver - this is the maximum number of parallel DNS requests that are
		1823	sent to the DNS server.
		1824
		1825	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1826
		1827	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1828	configuration) in the default resolver. When set to the empty string, no
		1829	default config will be used.
		1830
		1831	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1832
		1833	When neither C<ca_file> nor C<ca_path> was specified during
		1834	L<AnyEvent::TLS> context creation, and either of these environment
		1835	variables exist, they will be used to specify CA certificate locations
		1836	instead of a system-dependent default.
		1837
		1838	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1839
		1840	When these are set to C<1>, then the respective modules are not
		1841	loaded. Mostly good for testing AnyEvent itself.
		1842
		1843	=back
1094		1844
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1845	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		1846
1097	This is an advanced topic that you do not normally need to use AnyEvent in	1847	This is an advanced topic that you do not normally need to use AnyEvent in
1098	a module. This section is only of use to event loop authors who want to	1848	a module. This section is only of use to event loop authors who want to
…		…
1132		1882
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1883	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	1884	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	1885	C<die>. This still works with most modules/usages, and blocking calls must
1136	not be done in an interactive application, so it makes sense.	1886	not be done in an interactive application, so it makes sense.
1137
1138	=head1 ENVIRONMENT VARIABLES
1139
1140	The following environment variables are used by this module:
1141
1142	=over 4
1143
1144	=item C<PERL_ANYEVENT_VERBOSE>
1145
1146	By default, AnyEvent will be completely silent except in fatal
1147	conditions. You can set this environment variable to make AnyEvent more
1148	talkative.
1149
1150	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151	conditions, such as not being able to load the event model specified by
1152	C<PERL_ANYEVENT_MODEL>.
1153
1154	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155	model it chooses.
1156
1157	=item C<PERL_ANYEVENT_MODEL>
1158
1159	This can be used to specify the event model to be used by AnyEvent, before
1160	auto detection and -probing kicks in. It must be a string consisting
1161	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162	and the resulting module name is loaded and if the load was successful,
1163	used as event model. If it fails to load AnyEvent will proceed with
1164	auto detection and -probing.
1165
1166	This functionality might change in future versions.
1167
1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169	could start your program like this:
1170
1171	PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173	=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177	of auto probing).
1178
1179	Must be set to a comma-separated list of protocols or address families,
1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181	used, and preference will be given to protocols mentioned earlier in the
1182	list.
1183
1184	This variable can effectively be used for denial-of-service attacks
1185	against local programs (e.g. when setuid), although the impact is likely
1186	small, as the program has to handle connection errors already-
1187
1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190	- only support IPv4, never try to resolve or contact IPv6
1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192	IPv6, but prefer IPv6 over IPv4.
1193
1194	=item C<PERL_ANYEVENT_EDNS0>
1195
1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197	for DNS. This extension is generally useful to reduce DNS traffic, but
1198	some (broken) firewalls drop such DNS packets, which is why it is off by
1199	default.
1200
1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202	EDNS0 in its DNS requests.
1203
1204	=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207	will create in parallel.
1208
1209	=back
1210		1887
1211	=head1 EXAMPLE PROGRAM	1888	=head1 EXAMPLE PROGRAM
1212		1889
1213	The following program uses an I/O watcher to read data from STDIN, a timer	1890	The following program uses an I/O watcher to read data from STDIN, a timer
1214	to display a message once per second, and a condition variable to quit the	1891	to display a message once per second, and a condition variable to quit the
…		…
1408	watcher.	2085	watcher.
1409		2086
1410	=head3 Results	2087	=head3 Results
1411		2088
1412	name watchers bytes create invoke destroy comment	2089	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2090	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1414	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2091	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1415	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2092	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1416	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2093	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1417	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2094	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1418	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2095	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2096	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2097	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1419	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2098	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1420	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2099	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1421	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2100	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2101	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1423		2102
1424	=head3 Discussion	2103	=head3 Discussion
1425		2104
1426	The benchmark does I<not> measure scalability of the event loop very	2105	The benchmark does I<not> measure scalability of the event loop very
1427	well. For example, a select-based event loop (such as the pure perl one)	2106	well. For example, a select-based event loop (such as the pure perl one)
…		…
1452	performance becomes really bad with lots of file descriptors (and few of	2131	performance becomes really bad with lots of file descriptors (and few of
1453	them active), of course, but this was not subject of this benchmark.	2132	them active), of course, but this was not subject of this benchmark.
1454		2133
1455	The C<Event> module has a relatively high setup and callback invocation	2134	The C<Event> module has a relatively high setup and callback invocation
1456	cost, but overall scores in on the third place.	2135	cost, but overall scores in on the third place.
		2136
		2137	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2138	when using its pure perl backend.
1457		2139
1458	C<Glib>'s memory usage is quite a bit higher, but it features a	2140	C<Glib>'s memory usage is quite a bit higher, but it features a
1459	faster callback invocation and overall ends up in the same class as	2141	faster callback invocation and overall ends up in the same class as
1460	C<Event>. However, Glib scales extremely badly, doubling the number of	2142	C<Event>. However, Glib scales extremely badly, doubling the number of
1461	watchers increases the processing time by more than a factor of four,	2143	watchers increases the processing time by more than a factor of four,
…		…
1539	it to another server. This includes deleting the old timeout and creating	2221	it to another server. This includes deleting the old timeout and creating
1540	a new one that moves the timeout into the future.	2222	a new one that moves the timeout into the future.
1541		2223
1542	=head3 Results	2224	=head3 Results
1543		2225
1544	name sockets create request	2226	name sockets create request
1545	EV 20000 69.01 11.16	2227	EV 20000 69.01 11.16
1546	Perl 20000 73.32 35.87	2228	Perl 20000 73.32 35.87
		2229	IOAsync 20000 157.00 98.14 epoll
		2230	IOAsync 20000 159.31 616.06 poll
1547	Event 20000 212.62 257.32	2231	Event 20000 212.62 257.32
1548	Glib 20000 651.16 1896.30	2232	Glib 20000 651.16 1896.30
1549	POE 20000 349.67 12317.24 uses POE::Loop::Event	2233	POE 20000 349.67 12317.24 uses POE::Loop::Event
1550		2234
1551	=head3 Discussion	2235	=head3 Discussion
1552		2236
1553	This benchmark I<does> measure scalability and overall performance of the	2237	This benchmark I<does> measure scalability and overall performance of the
1554	particular event loop.	2238	particular event loop.
…		…
1556	EV is again fastest. Since it is using epoll on my system, the setup time	2240	EV is again fastest. Since it is using epoll on my system, the setup time
1557	is relatively high, though.	2241	is relatively high, though.
1558		2242
1559	Perl surprisingly comes second. It is much faster than the C-based event	2243	Perl surprisingly comes second. It is much faster than the C-based event
1560	loops Event and Glib.	2244	loops Event and Glib.
		2245
		2246	IO::Async performs very well when using its epoll backend, and still quite
		2247	good compared to Glib when using its pure perl backend.
1561		2248
1562	Event suffers from high setup time as well (look at its code and you will	2249	Event suffers from high setup time as well (look at its code and you will
1563	understand why). Callback invocation also has a high overhead compared to	2250	understand why). Callback invocation also has a high overhead compared to
1564	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2251	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565	uses select or poll in basically all documented configurations.	2252	uses select or poll in basically all documented configurations.
…		…
1628	=item * C-based event loops perform very well with small number of	2315	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	2316	watchers, as the management overhead dominates.
1630		2317
1631	=back	2318	=back
1632		2319
		2320	=head2 THE IO::Lambda BENCHMARK
		2321
		2322	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2323	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2324	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2325	shouldn't come as a surprise to anybody). As such, the benchmark is
		2326	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2327	very optimal. But how would AnyEvent compare when used without the extra
		2328	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2329
		2330	The benchmark itself creates an echo-server, and then, for 500 times,
		2331	connects to the echo server, sends a line, waits for the reply, and then
		2332	creates the next connection. This is a rather bad benchmark, as it doesn't
		2333	test the efficiency of the framework or much non-blocking I/O, but it is a
		2334	benchmark nevertheless.
		2335
		2336	name runtime
		2337	Lambda/select 0.330 sec
		2338	+ optimized 0.122 sec
		2339	Lambda/AnyEvent 0.327 sec
		2340	+ optimized 0.138 sec
		2341	Raw sockets/select 0.077 sec
		2342	POE/select, components 0.662 sec
		2343	POE/select, raw sockets 0.226 sec
		2344	POE/select, optimized 0.404 sec
		2345
		2346	AnyEvent/select/nb 0.085 sec
		2347	AnyEvent/EV/nb 0.068 sec
		2348	+state machine 0.134 sec
		2349
		2350	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2351	benchmarks actually make blocking connects and use 100% blocking I/O,
		2352	defeating the purpose of an event-based solution. All of the newly
		2353	written AnyEvent benchmarks use 100% non-blocking connects (using
		2354	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2355	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2356	generally require a lot more bookkeeping and event handling than blocking
		2357	connects (which involve a single syscall only).
		2358
		2359	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2360	offers similar expressive power as POE and IO::Lambda, using conventional
		2361	Perl syntax. This means that both the echo server and the client are 100%
		2362	non-blocking, further placing it at a disadvantage.
		2363
		2364	As you can see, the AnyEvent + EV combination even beats the
		2365	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2366	backend easily beats IO::Lambda and POE.
		2367
		2368	And even the 100% non-blocking version written using the high-level (and
		2369	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2370	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2371	in a non-blocking way.
		2372
		2373	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2374	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2375	part of the IO::lambda distribution and were used without any changes.
		2376
		2377
		2378	=head1 SIGNALS
		2379
		2380	AnyEvent currently installs handlers for these signals:
		2381
		2382	=over 4
		2383
		2384	=item SIGCHLD
		2385
		2386	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2387	emulation for event loops that do not support them natively. Also, some
		2388	event loops install a similar handler.
		2389
		2390	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2391	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2392
		2393	=item SIGPIPE
		2394
		2395	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2396	when AnyEvent gets loaded.
		2397
		2398	The rationale for this is that AnyEvent users usually do not really depend
		2399	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2400	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2401	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2402	some random socket.
		2403
		2404	The rationale for installing a no-op handler as opposed to ignoring it is
		2405	that this way, the handler will be restored to defaults on exec.
		2406
		2407	Feel free to install your own handler, or reset it to defaults.
		2408
		2409	=back
		2410
		2411	=cut
		2412
		2413	undef $SIG{CHLD}
		2414	if $SIG{CHLD} eq 'IGNORE';
		2415
		2416	$SIG{PIPE} = sub { }
		2417	unless defined $SIG{PIPE};
		2418
		2419	=head1 RECOMMENDED/OPTIONAL MODULES
		2420
		2421	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2422	it's built-in modules) are required to use it.
		2423
		2424	That does not mean that AnyEvent won't take advantage of some additional
		2425	modules if they are installed.
		2426
		2427	This section epxlains which additional modules will be used, and how they
		2428	affect AnyEvent's operetion.
		2429
		2430	=over 4
		2431
		2432	=item L<Async::Interrupt>
		2433
		2434	This slightly arcane module is used to implement fast signal handling: To
		2435	my knowledge, there is no way to do completely race-free and quick
		2436	signal handling in pure perl. To ensure that signals still get
		2437	delivered, AnyEvent will start an interval timer to wake up perl (and
		2438	catch the signals) with some delay (default is 10 seconds, look for
		2439	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2440
		2441	If this module is available, then it will be used to implement signal
		2442	catching, which means that signals will not be delayed, and the event loop
		2443	will not be interrupted regularly, which is more efficient (And good for
		2444	battery life on laptops).
		2445
		2446	This affects not just the pure-perl event loop, but also other event loops
		2447	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2448
		2449	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2450	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2451	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2452	does nothing for those backends.
		2453
		2454	=item L<EV>
		2455
		2456	This module isn't really "optional", as it is simply one of the backend
		2457	event loops that AnyEvent can use. However, it is simply the best event
		2458	loop available in terms of features, speed and stability: It supports
		2459	the AnyEvent API optimally, implements all the watcher types in XS, does
		2460	automatic timer adjustments even when no monotonic clock is available,
		2461	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2462	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2463	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2464
		2465	=item L<Guard>
		2466
		2467	The guard module, when used, will be used to implement
		2468	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2469	lot less memory), but otherwise doesn't affect guard operation much. It is
		2470	purely used for performance.
		2471
		2472	=item L<JSON> and L<JSON::XS>
		2473
		2474	This module is required when you want to read or write JSON data via
		2475	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2476	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2477
		2478	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2479	installed.
		2480
		2481	=item L<Net::SSLeay>
		2482
		2483	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2484	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2485	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2486
		2487	=item L<Time::HiRes>
		2488
		2489	This module is part of perl since release 5.008. It will be used when the
		2490	chosen event library does not come with a timing source on it's own. The
		2491	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2492	try to use a monotonic clock for timing stability.
		2493
		2494	=back
		2495
1633		2496
1634	=head1 FORK	2497	=head1 FORK
1635		2498
1636	Most event libraries are not fork-safe. The ones who are usually are	2499	Most event libraries are not fork-safe. The ones who are usually are
1637	because they rely on inefficient but fork-safe C<select> or C<poll>	2500	because they rely on inefficient but fork-safe C<select> or C<poll>
1638	calls. Only L<EV> is fully fork-aware.	2501	calls. Only L<EV> is fully fork-aware.
1639		2502
1640	If you have to fork, you must either do so I<before> creating your first	2503	If you have to fork, you must either do so I<before> creating your first
1641	watcher OR you must not use AnyEvent at all in the child.	2504	watcher OR you must not use AnyEvent at all in the child OR you must do
		2505	something completely out of the scope of AnyEvent.
1642		2506
1643		2507
1644	=head1 SECURITY CONSIDERATIONS	2508	=head1 SECURITY CONSIDERATIONS
1645		2509
1646	AnyEvent can be forced to load any event model via	2510	AnyEvent can be forced to load any event model via
…		…
1651	specified in the variable.	2515	specified in the variable.
1652		2516
1653	You can make AnyEvent completely ignore this variable by deleting it	2517	You can make AnyEvent completely ignore this variable by deleting it
1654	before the first watcher gets created, e.g. with a C<BEGIN> block:	2518	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2519
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2520	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2521
1658	use AnyEvent;	2522	use AnyEvent;
1659		2523
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2524	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661	be used to probe what backend is used and gain other information (which is	2525	be used to probe what backend is used and gain other information (which is
1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2526	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2527	$ENV{PERL_ANYEVENT_STRICT}.
		2528
		2529	Note that AnyEvent will remove I<all> environment variables starting with
		2530	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2531	enabled.
		2532
		2533
		2534	=head1 BUGS
		2535
		2536	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2537	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2538	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2539	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2540	pronounced).
1663		2541
1664		2542
1665	=head1 SEE ALSO	2543	=head1 SEE ALSO
1666		2544
1667	Utility functions: L<AnyEvent::Util>.	2545	Utility functions: L<AnyEvent::Util>.
…		…
1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2548	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1671		2549
1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2550	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2551	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2552	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1675	L<AnyEvent::Impl::POE>.	2553	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1676		2554
1677	Non-blocking file handles, sockets, TCP clients and	2555	Non-blocking file handles, sockets, TCP clients and
1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2556	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1679		2557
1680	Asynchronous DNS: L<AnyEvent::DNS>.	2558	Asynchronous DNS: L<AnyEvent::DNS>.
1681		2559
1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2560	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2561	L<Coro::Event>,
1683		2562
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2563	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2564	L<AnyEvent::HTTP>.
1685		2565
1686		2566
1687	=head1 AUTHOR	2567	=head1 AUTHOR
1688		2568
1689	Marc Lehmann <schmorp@schmorp.de>	2569	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	2570	http://home.schmorp.de/
1691		2571
1692	=cut	2572	=cut
1693		2573
1694	1	2574	1
1695		2575

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