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Revision 1.144 by root, Thu May 29 00:14:35 2008 UTC vs.
Revision 1.251 by root, Mon Jul 20 22:39:57 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
		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	Respository>, 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
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
150		188
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
152	for events. C<poll> must be a string that is either C<r> or C<w>,	196	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,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
154	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		200
157	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
160		204
…		…
164		208
165	Some event loops issue spurious readyness notifications, so you should	209	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	210	always use non-blocking calls when reading/writing from/to your file
167	handles.	211	handles.
168		212
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	213	Example: wait for readability of STDIN, then read a line and disable the
		214	watcher.
		215
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	216	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	217	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	218	warn "read: $input\n";
175	undef $w;	219	undef $w;
176	});	220	});
…		…
186		230
187	Although the callback might get passed parameters, their value and	231	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	232	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	233	callbacks cannot use arguments passed to time watcher callbacks.
190		234
191	The timer callback will be invoked at most once: if you want a repeating	235	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	236	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	237	callback will be invoked regularly at that interval (in fractional
		238	seconds) after the first invocation. If C<interval> is specified with a
		239	false value, then it is treated as if it were missing.
194		240
195	Example:	241	The callback will be rescheduled before invoking the callback, but no
		242	attempt is done to avoid timer drift in most backends, so the interval is
		243	only approximate.
196		244
197	# fire an event after 7.7 seconds	245	Example: fire an event after 7.7 seconds.
		246
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	247	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	248	warn "timeout\n";
200	});	249	});
201		250
202	# to cancel the timer:	251	# to cancel the timer:
203	undef $w;	252	undef $w;
204		253
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	254	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		255
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	256	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		257	warn "timeout\n";
213	};	258	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		259
218	=head3 TIMING ISSUES	260	=head3 TIMING ISSUES
219		261
220	There are two ways to handle timers: based on real time (relative, "fire	262	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	263	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	336	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	337	can get whatever behaviour you want with any event loop, by taking the
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	339	account.
298		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
299	=back	356	=back
300		357
301	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
302		359
303	You can watch for signals using a signal watcher, C<signal> is the signal	360	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	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
305	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
306		363
307	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
310		367
…		…
312	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
313	that it might take a while until the signal gets handled by the process,	370	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.	371	but it is guaranteed not to interrupt any other callbacks.
315		372
316	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
317	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
318		376
319	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
320	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
321		380
322	Example: exit on SIGINT	381	Example: exit on SIGINT
323		382
324	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
325		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
326	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
327		402
328	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
329		404
330	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (if set to C<0>, it
331	watches for any child process exit). The watcher will trigger as often	406	watches for any child process exit). The watcher will triggered only when
332	as status change for the child are received. This works by installing a	407	the child process has finished and an exit status is available, not on
333	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
334	and exit status (as returned by waitpid), so unlike other watcher types,	409
335	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
336		418
337	There is a slight catch to child watchers, however: you usually start them	419	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	420	I<after> the child process was created, and this means the process could
339	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
340		422
341	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	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	425	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).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
344		429
345	This means you cannot create a child watcher as the very first thing in an	430	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	431	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>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
348		438
349	Example: fork a process and wait for it	439	Example: fork a process and wait for it
350		440
351	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
352		442
353	my $pid = fork or exit 5;	443	my $pid = fork or exit 5;
354		444
355	my $w = AnyEvent->child (	445	my $w = AnyEvent->child (
356	pid => $pid,	446	pid => $pid,
357	cb => sub {	447	cb => sub {
358	my ($pid, $status) = @_;	448	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	449	warn "pid $pid exited with status $status";
360	$done->send;	450	$done->send;
361	},	451	},
362	);	452	);
363		453
364	# do something else, then wait for process exit	454	# do something else, then wait for process exit
365	$done->recv;	455	$done->recv;
		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
366		491
367	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
368		493
369	If you are familiar with some event loops you will know that all of them	494	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	495	require you to run some blocking "loop", "run" or similar function that
371	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
372		497
373	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
374	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
375		500
376	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
377	because they represent a condition that must become true.	502	because they represent a condition that must become true.
		503
		504	Now is probably a good time to look at the examples further below.
378		505
379	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
381	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
382	becomes true.	509	becomes true, with the condition variable as the first argument (but not
		510	the results).
383		511
384	After creation, the condition variable is "false" until it becomes "true"	512	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	513	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<<	514	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	515	->send >> method).
…		…
389	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
390	optionally wait for them. They can also be called merge points - points	518	optionally wait for them. They can also be called merge points - points
391	in time where multiple outstanding events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
392	another way to call them is transactions - each condition variable can be	520	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	521	used to represent a transaction, which finishes at some point and delivers
394	a result.	522	a result. And yet some people know them as "futures" - a promise to
		523	compute/deliver something that you can wait for.
395		524
396	Condition variables are very useful to signal that something has finished,	525	Condition variables are very useful to signal that something has finished,
397	for example, if you write a module that does asynchronous http requests,	526	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	527	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	528	availability of results. The user can either act when the callback is
…		…
433	after => 1,	562	after => 1,
434	cb => sub { $result_ready->send },	563	cb => sub { $result_ready->send },
435	);	564	);
436		565
437	# this "blocks" (while handling events) till the callback	566	# this "blocks" (while handling events) till the callback
438	# calls send	567	# calls -<send
439	$result_ready->recv;	568	$result_ready->recv;
440		569
441	Example: wait for a timer, but take advantage of the fact that	570	Example: wait for a timer, but take advantage of the fact that condition
442	condition variables are also code references.	571	variables are also callable directly.
443		572
444	my $done = AnyEvent->condvar;	573	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	574	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$done->recv;	575	$done->recv;
		576
		577	Example: Imagine an API that returns a condvar and doesn't support
		578	callbacks. This is how you make a synchronous call, for example from
		579	the main program:
		580
		581	use AnyEvent::CouchDB;
		582
		583	...
		584
		585	my @info = $couchdb->info->recv;
		586
		587	And this is how you would just set a callback to be called whenever the
		588	results are available:
		589
		590	$couchdb->info->cb (sub {
		591	my @info = $_[0]->recv;
		592	});
447		593
448	=head3 METHODS FOR PRODUCERS	594	=head3 METHODS FOR PRODUCERS
449		595
450	These methods should only be used by the producing side, i.e. the	596	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	597	code/module that eventually sends the signal. Note that it is also
…		…
464	immediately from within send.	610	immediately from within send.
465		611
466	Any arguments passed to the C<send> call will be returned by all	612	Any arguments passed to the C<send> call will be returned by all
467	future C<< ->recv >> calls.	613	future C<< ->recv >> calls.
468		614
469	Condition variables are overloaded so one can call them directly	615	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	616	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	617	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		618
478	=item $cv->croak ($error)	619	=item $cv->croak ($error)
479		620
480	Similar to send, but causes all call's to C<< ->recv >> to invoke	621	Similar to send, but causes all call's to C<< ->recv >> to invoke
481	C<Carp::croak> with the given error message/object/scalar.	622	C<Carp::croak> with the given error message/object/scalar.
482		623
483	This can be used to signal any errors to the condition variable	624	This can be used to signal any errors to the condition variable
484	user/consumer.	625	user/consumer. Doing it this way instead of calling C<croak> directly
		626	delays the error detetcion, but has the overwhelmign advantage that it
		627	diagnoses the error at the place where the result is expected, and not
		628	deep in some event clalback without connection to the actual code causing
		629	the problem.
485		630
486	=item $cv->begin ([group callback])	631	=item $cv->begin ([group callback])
487		632
488	=item $cv->end	633	=item $cv->end
489
490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
491		634
492	These two methods can be used to combine many transactions/events into	635	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	636	one. For example, a function that pings many hosts in parallel might want
494	to use a condition variable for the whole process.	637	to use a condition variable for the whole process.
495		638
…		…
497	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	640	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	641	>>, 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	642	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.	643	callback was set, C<send> will be called without any arguments.
501		644
502	Let's clarify this with the ping example:	645	You can think of C<< $cv->send >> giving you an OR condition (one call
		646	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		647	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		648
		649	Let's start with a simple example: you have two I/O watchers (for example,
		650	STDOUT and STDERR for a program), and you want to wait for both streams to
		651	close before activating a condvar:
		652
		653	my $cv = AnyEvent->condvar;
		654
		655	$cv->begin; # first watcher
		656	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		657	defined sysread $fh1, my $buf, 4096
		658	or $cv->end;
		659	});
		660
		661	$cv->begin; # second watcher
		662	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		663	defined sysread $fh2, my $buf, 4096
		664	or $cv->end;
		665	});
		666
		667	$cv->recv;
		668
		669	This works because for every event source (EOF on file handle), there is
		670	one call to C<begin>, so the condvar waits for all calls to C<end> before
		671	sending.
		672
		673	The ping example mentioned above is slightly more complicated, as the
		674	there are results to be passwd back, and the number of tasks that are
		675	begung can potentially be zero:
503		676
504	my $cv = AnyEvent->condvar;	677	my $cv = AnyEvent->condvar;
505		678
506	my %result;	679	my %result;
507	$cv->begin (sub { $cv->send (\%result) });	680	$cv->begin (sub { $cv->send (\%result) });
…		…
527	loop, which serves two important purposes: first, it sets the callback	700	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	701	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	702	C<send> is called even when C<no> hosts are being pinged (the loop
530	doesn't execute once).	703	doesn't execute once).
531		704
532	This is the general pattern when you "fan out" into multiple subrequests:	705	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>	706	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	707	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>.	708	subrequest you start, call C<begin> and for each subrequest you finish,
		709	call C<end>.
536		710
537	=back	711	=back
538		712
539	=head3 METHODS FOR CONSUMERS	713	=head3 METHODS FOR CONSUMERS
540		714
…		…
556	function will call C<croak>.	730	function will call C<croak>.
557		731
558	In list context, all parameters passed to C<send> will be returned,	732	In list context, all parameters passed to C<send> will be returned,
559	in scalar context only the first one will be returned.	733	in scalar context only the first one will be returned.
560		734
		735	Note that doing a blocking wait in a callback is not supported by any
		736	event loop, that is, recursive invocation of a blocking C<< ->recv
		737	>> is not allowed, and the C<recv> call will C<croak> if such a
		738	condition is detected. This condition can be slightly loosened by using
		739	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		740	any thread that doesn't run the event loop itself.
		741
561	Not all event models support a blocking wait - some die in that case	742	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	743	(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	744	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	745	caller decide whether the call will block or not (for example, by coupling
565	condition variables with some kind of request results and supporting	746	condition variables with some kind of request results and supporting
566	callbacks so the caller knows that getting the result will not block,	747	callbacks so the caller knows that getting the result will not block,
567	while still supporting blocking waits if the caller so desires).	748	while still supporting blocking waits if the caller so desires).
568		749
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	750	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	751	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	752	time). This will work even when the event loop does not support blocking
583	waits otherwise.	753	waits otherwise.
584		754
585	=item $bool = $cv->ready	755	=item $bool = $cv->ready
586		756
587	Returns true when the condition is "true", i.e. whether C<send> or	757	Returns true when the condition is "true", i.e. whether C<send> or
588	C<croak> have been called.	758	C<croak> have been called.
589		759
590	=item $cb = $cv->cb ([new callback])	760	=item $cb = $cv->cb ($cb->($cv))
591		761
592	This is a mutator function that returns the callback set and optionally	762	This is a mutator function that returns the callback set and optionally
593	replaces it before doing so.	763	replaces it before doing so.
594		764
595	The callback will be called when the condition becomes "true", i.e. when	765	The callback will be called when the condition becomes "true", i.e. when
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	766	C<send> or C<croak> are called, with the only argument being the condition
597	or at any later time is guaranteed not to block.	767	variable itself. Calling C<recv> inside the callback or at any later time
		768	is guaranteed not to block.
598		769
599	=back	770	=back
600		771
		772	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		773
		774	The available backend classes are (every class has its own manpage):
		775
		776	=over 4
		777
		778	=item Backends that are autoprobed when no other event loop can be found.
		779
		780	EV is the preferred backend when no other event loop seems to be in
		781	use. If EV is not installed, then AnyEvent will try Event, and, failing
		782	that, will fall back to its own pure-perl implementation, which is
		783	available everywhere as it comes with AnyEvent itself.
		784
		785	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		786	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		787	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		788
		789	=item Backends that are transparently being picked up when they are used.
		790
		791	These will be used when they are currently loaded when the first watcher
		792	is created, in which case it is assumed that the application is using
		793	them. This means that AnyEvent will automatically pick the right backend
		794	when the main program loads an event module before anything starts to
		795	create watchers. Nothing special needs to be done by the main program.
		796
		797	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		798	AnyEvent::Impl::Tk based on Tk, very broken.
		799	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		800	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		801
		802	=item Backends with special needs.
		803
		804	Qt requires the Qt::Application to be instantiated first, but will
		805	otherwise be picked up automatically. As long as the main program
		806	instantiates the application before any AnyEvent watchers are created,
		807	everything should just work.
		808
		809	AnyEvent::Impl::Qt based on Qt.
		810
		811	Support for IO::Async can only be partial, as it is too broken and
		812	architecturally limited to even support the AnyEvent API. It also
		813	is the only event loop that needs the loop to be set explicitly, so
		814	it can only be used by a main program knowing about AnyEvent. See
		815	L<AnyEvent::Impl::Async> for the gory details.
		816
		817	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		818
		819	=item Event loops that are indirectly supported via other backends.
		820
		821	Some event loops can be supported via other modules:
		822
		823	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		824
		825	B<WxWidgets> has no support for watching file handles. However, you can
		826	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		827	polls 20 times per second, which was considered to be too horrible to even
		828	consider for AnyEvent.
		829
		830	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		831	backend, so it can be supported through POE.
		832
		833	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		834	load L<POE> when detecting them, in the hope that POE will pick them up,
		835	in which case everything will be automatic.
		836
		837	=back
		838
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
603	=over 4	844	=over 4
604		845
605	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
606		847
607	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
608	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
609	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
612		855	will be C<urxvt::anyevent>).
613	The known classes so far are:
614
615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
616	AnyEvent::Impl::Event based on Event, second best choice.
617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
618	AnyEvent::Impl::Glib based on Glib, third-best choice.
619	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623
624	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
629	it's adaptor.
630
631	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
632	autodetecting them.
633		856
634	=item AnyEvent::detect	857	=item AnyEvent::detect
635		858
636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
637	if necessary. You should only call this function right before you would	860	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	861	have created an AnyEvent watcher anyway, that is, as late as possible at
639	runtime.	862	runtime, and not e.g. while initialising of your module.
		863
		864	If you need to do some initialisation before AnyEvent watchers are
		865	created, use C<post_detect>.
640		866
641	=item $guard = AnyEvent::post_detect { BLOCK }	867	=item $guard = AnyEvent::post_detect { BLOCK }
642		868
643	Arranges for the code block to be executed as soon as the event model is	869	Arranges for the code block to be executed as soon as the event model is
644	autodetected (or immediately if this has already happened).	870	autodetected (or immediately if this has already happened).
		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		874	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		875	other initialisations - see the sources of L<AnyEvent::Strict> or
		876	L<AnyEvent::AIO> to see how this is used.
		877
		878	The most common usage is to create some global watchers, without forcing
		879	event module detection too early, for example, L<AnyEvent::AIO> creates
		880	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		881	avoid autodetecting the event module at load time.
645		882
646	If called in scalar or list context, then it creates and returns an object	883	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	884	that automatically removes the callback again when it is destroyed. See
648	L<Coro::BDB> for a case where this is useful.	885	L<Coro::BDB> for a case where this is useful.
649		886
…		…
652	If there are any code references in this array (you can C<push> to it	889	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	890	before or after loading AnyEvent), then they will called directly after
654	the event loop has been chosen.	891	the event loop has been chosen.
655		892
656	You should check C<$AnyEvent::MODEL> before adding to this array, though:	893	You should check C<$AnyEvent::MODEL> before adding to this array, though:
657	if it contains a true value then the event loop has already been detected,	894	if it is defined then the event loop has already been detected, and the
658	and the array will be ignored.	895	array will be ignored.
659		896
660	Best use C<AnyEvent::post_detect { BLOCK }> instead.	897	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		898	it,as it takes care of these details.
		899
		900	This variable is mainly useful for modules that can do something useful
		901	when AnyEvent is used and thus want to know when it is initialised, but do
		902	not need to even load it by default. This array provides the means to hook
		903	into AnyEvent passively, without loading it.
661		904
662	=back	905	=back
663		906
664	=head1 WHAT TO DO IN A MODULE	907	=head1 WHAT TO DO IN A MODULE
665		908
…		…
720		963
721		964
722	=head1 OTHER MODULES	965	=head1 OTHER MODULES
723		966
724	The following is a non-exhaustive list of additional modules that use	967	The following is a non-exhaustive list of additional modules that use
725	AnyEvent and can therefore be mixed easily with other AnyEvent modules	968	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	969	modules and other event loops in the same program. Some of the modules
727	available via CPAN.	970	come with AnyEvent, most are available via CPAN.
728		971
729	=over 4	972	=over 4
730		973
731	=item L<AnyEvent::Util>	974	=item L<AnyEvent::Util>
732		975
733	Contains various utility functions that replace often-used but blocking	976	Contains various utility functions that replace often-used but blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	977	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		978
740	=item L<AnyEvent::Socket>	979	=item L<AnyEvent::Socket>
741		980
742	Provides various utility functions for (internet protocol) sockets,	981	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	982	addresses and name resolution. Also functions to create non-blocking tcp
744	connections or tcp servers, with IPv6 and SRV record support and more.	983	connections or tcp servers, with IPv6 and SRV record support and more.
745		984
		985	=item L<AnyEvent::Handle>
		986
		987	Provide read and write buffers, manages watchers for reads and writes,
		988	supports raw and formatted I/O, I/O queued and fully transparent and
		989	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		990
746	=item L<AnyEvent::DNS>	991	=item L<AnyEvent::DNS>
747		992
748	Provides rich asynchronous DNS resolver capabilities.	993	Provides rich asynchronous DNS resolver capabilities.
749		994
		995	=item L<AnyEvent::HTTP>
		996
		997	A simple-to-use HTTP library that is capable of making a lot of concurrent
		998	HTTP requests.
		999
750	=item L<AnyEvent::HTTPD>	1000	=item L<AnyEvent::HTTPD>
751		1001
752	Provides a simple web application server framework.	1002	Provides a simple web application server framework.
753		1003
754	=item L<AnyEvent::FastPing>	1004	=item L<AnyEvent::FastPing>
755		1005
756	The fastest ping in the west.	1006	The fastest ping in the west.
757		1007
		1008	=item L<AnyEvent::DBI>
		1009
		1010	Executes L<DBI> requests asynchronously in a proxy process.
		1011
		1012	=item L<AnyEvent::AIO>
		1013
		1014	Truly asynchronous I/O, should be in the toolbox of every event
		1015	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1016	together.
		1017
		1018	=item L<AnyEvent::BDB>
		1019
		1020	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1021	L<BDB> and AnyEvent together.
		1022
		1023	=item L<AnyEvent::GPSD>
		1024
		1025	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1026
758	=item L<Net::IRC3>	1027	=item L<AnyEvent::IRC>
759		1028
760	AnyEvent based IRC client module family.	1029	AnyEvent based IRC client module family (replacing the older Net::IRC3).
761		1030
762	=item L<Net::XMPP2>	1031	=item L<AnyEvent::XMPP>
763		1032
764	AnyEvent based XMPP (Jabber protocol) module family.	1033	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1034	Net::XMPP2>.
		1035
		1036	=item L<AnyEvent::IGS>
		1037
		1038	A non-blocking interface to the Internet Go Server protocol (used by
		1039	L<App::IGS>).
765		1040
766	=item L<Net::FCP>	1041	=item L<Net::FCP>
767		1042
768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1043	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
769	of AnyEvent.	1044	of AnyEvent.
…		…
774		1049
775	=item L<Coro>	1050	=item L<Coro>
776		1051
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	1052	Has special support for AnyEvent via L<Coro::AnyEvent>.
778		1053
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	1054	=back
795		1055
796	=cut	1056	=cut
797		1057
798	package AnyEvent;	1058	package AnyEvent;
799		1059
		1060	# basically a tuned-down version of common::sense
		1061	sub common_sense {
800	no warnings;	1062	# no warnings
801	use strict;	1063	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1064	# use strict vars subs
		1065	$^H |= 0x00000600;
		1066	}
802		1067
		1068	BEGIN { AnyEvent::common_sense }
		1069
803	use Carp;	1070	use Carp ();
804		1071
805	our $VERSION = '4.05';	1072	our $VERSION = 4.86;
806	our $MODEL;	1073	our $MODEL;
807		1074
808	our $AUTOLOAD;	1075	our $AUTOLOAD;
809	our @ISA;	1076	our @ISA;
810		1077
811	our @REGISTRY;	1078	our @REGISTRY;
812		1079
813	our $WIN32;	1080	our $WIN32;
814		1081
		1082	our $VERBOSE;
		1083
815	BEGIN {	1084	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	1085	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
817	eval "sub WIN32(){ $win32 }";	1086	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
818	}
819		1087
		1088	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1089	if ${^TAINT};
		1090
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1091	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1092
		1093	}
		1094
		1095	our $MAX_SIGNAL_LATENCY = 10;
821		1096
822	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1097	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
823		1098
824	{	1099	{
825	my $idx;	1100	my $idx;
…		…
833	[Event:: => AnyEvent::Impl::Event::],	1108	[Event:: => AnyEvent::Impl::Event::],
834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1109	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
835	# everything below here will not be autoprobed	1110	# everything below here will not be autoprobed
836	# as the pureperl backend should work everywhere	1111	# as the pureperl backend should work everywhere
837	# and is usually faster	1112	# and is usually faster
838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1113	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1114	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1115	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1116	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1117	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	1118	[Wx:: => AnyEvent::Impl::POE::],
844	[Prima:: => AnyEvent::Impl::POE::],	1119	[Prima:: => AnyEvent::Impl::POE::],
		1120	# IO::Async is just too broken - we would need workarounds for its
		1121	# byzantine signal and broken child handling, among others.
		1122	# IO::Async is rather hard to detect, as it doesn't have any
		1123	# obvious default class.
		1124	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1126	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
845	);	1127	);
846		1128
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1129	our %method = map +($_ => 1),
		1130	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
848		1131
849	our @post_detect;	1132	our @post_detect;
850		1133
851	sub post_detect(&) {	1134	sub post_detect(&) {
852	my ($cb) = @_;	1135	my ($cb) = @_;
…		…
857	1	1140	1
858	} else {	1141	} else {
859	push @post_detect, $cb;	1142	push @post_detect, $cb;
860		1143
861	defined wantarray	1144	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"	1145	? bless \$cb, "AnyEvent::Util::postdetect"
863	: ()	1146	: ()
864	}	1147	}
865	}	1148	}
866		1149
867	sub AnyEvent::Util::PostDetect::DESTROY {	1150	sub AnyEvent::Util::postdetect::DESTROY {
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1151	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}	1152	}
870		1153
871	sub detect() {	1154	sub detect() {
872	unless ($MODEL) {	1155	unless ($MODEL) {
873	no strict 'refs';
874	local $SIG{__DIE__};	1156	local $SIG{__DIE__};
875		1157
876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1158	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
877	my $model = "AnyEvent::Impl::$1";	1159	my $model = "AnyEvent::Impl::$1";
878	if (eval "require $model") {	1160	if (eval "require $model") {
879	$MODEL = $model;	1161	$MODEL = $model;
880	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1162	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
881	} else {	1163	} else {
882	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1164	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
883	}	1165	}
884	}	1166	}
885		1167
886	# check for already loaded models	1168	# check for already loaded models
887	unless ($MODEL) {	1169	unless ($MODEL) {
888	for (@REGISTRY, @models) {	1170	for (@REGISTRY, @models) {
889	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
890	if (${"$package\::VERSION"} > 0) {	1172	if (${"$package\::VERSION"} > 0) {
891	if (eval "require $model") {	1173	if (eval "require $model") {
892	$MODEL = $model;	1174	$MODEL = $model;
893	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1175	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
894	last;	1176	last;
895	}	1177	}
896	}	1178	}
897	}	1179	}
898		1180
…		…
903	my ($package, $model) = @$_;	1185	my ($package, $model) = @$_;
904	if (eval "require $package"	1186	if (eval "require $package"
905	and ${"$package\::VERSION"} > 0	1187	and ${"$package\::VERSION"} > 0
906	and eval "require $model") {	1188	and eval "require $model") {
907	$MODEL = $model;	1189	$MODEL = $model;
908	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1190	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
909	last;	1191	last;
910	}	1192	}
911	}	1193	}
912		1194
913	$MODEL	1195	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1196	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
915	}	1197	}
916	}	1198	}
917		1199
		1200	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1201
918	unshift @ISA, $MODEL;	1202	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1203
		1204	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
920		1205
921	(shift @post_detect)->() while @post_detect;	1206	(shift @post_detect)->() while @post_detect;
922	}	1207	}
923		1208
924	$MODEL	1209	$MODEL
…		…
926		1211
927	sub AUTOLOAD {	1212	sub AUTOLOAD {
928	(my $func = $AUTOLOAD) =~ s/.*://;	1213	(my $func = $AUTOLOAD) =~ s/.*://;
929		1214
930	$method{$func}	1215	$method{$func}
931	or croak "$func: not a valid method for AnyEvent objects";	1216	or Carp::croak "$func: not a valid method for AnyEvent objects";
932		1217
933	detect unless $MODEL;	1218	detect unless $MODEL;
934		1219
935	my $class = shift;	1220	my $class = shift;
936	$class->$func (@_);	1221	$class->$func (@_);
937	}	1222	}
938		1223
		1224	# utility function to dup a filehandle. this is used by many backends
		1225	# to support binding more than one watcher per filehandle (they usually
		1226	# allow only one watcher per fd, so we dup it to get a different one).
		1227	sub _dupfh($$;$$) {
		1228	my ($poll, $fh, $r, $w) = @_;
		1229
		1230	# cygwin requires the fh mode to be matching, unix doesn't
		1231	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1232
		1233	open my $fh2, $mode, $fh
		1234	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1235
		1236	# we assume CLOEXEC is already set by perl in all important cases
		1237
		1238	($fh2, $rw)
		1239	}
		1240
939	package AnyEvent::Base;	1241	package AnyEvent::Base;
940		1242
941	# default implementation for now and time	1243	# default implementations for many methods
942		1244
943	use Time::HiRes ();	1245	sub _time {
		1246	# probe for availability of Time::HiRes
		1247	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1248	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1249	*_time = \&Time::HiRes::time;
		1250	# if (eval "use POSIX (); (POSIX::times())...
		1251	} else {
		1252	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1253	*_time = sub { time }; # epic fail
		1254	}
944		1255
945	sub time { Time::HiRes::time }	1256	&_time
946	sub now { Time::HiRes::time }	1257	}
		1258
		1259	sub time { _time }
		1260	sub now { _time }
		1261	sub now_update { }
947		1262
948	# default implementation for ->condvar	1263	# default implementation for ->condvar
949		1264
950	sub condvar {	1265	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1266	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
952	}	1267	}
953		1268
954	# default implementation for ->signal	1269	# default implementation for ->signal
955		1270
956	our %SIG_CB;	1271	our $HAVE_ASYNC_INTERRUPT;
		1272	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1273	our (%SIG_ASY, %SIG_ASY_W);
		1274	our ($SIG_COUNT, $SIG_TW);
957		1275
		1276	sub _signal_exec {
		1277	$HAVE_ASYNC_INTERRUPT
		1278	? $SIGPIPE_R->drain
		1279	: sysread $SIGPIPE_R, my $dummy, 9;
		1280
		1281	while (%SIG_EV) {
		1282	for (keys %SIG_EV) {
		1283	delete $SIG_EV{$_};
		1284	$_->() for values %{ $SIG_CB{$_} || {} };
		1285	}
		1286	}
		1287	}
		1288
		1289	# install a dumym wakeupw atcher to reduce signal catching latency
		1290	sub _sig_add() {
		1291	unless ($SIG_COUNT++) {
		1292	# try to align timer on a full-second boundary, if possible
		1293	my $NOW = AnyEvent->now;
		1294
		1295	$SIG_TW = AnyEvent->timer (
		1296	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1297	interval => $MAX_SIGNAL_LATENCY,
		1298	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1299	);
		1300	}
		1301	}
		1302
		1303	sub _sig_del {
		1304	undef $SIG_TW
		1305	unless --$SIG_COUNT;
		1306	}
		1307
958	sub signal {	1308	sub _signal {
959	my (undef, %arg) = @_;	1309	my (undef, %arg) = @_;
960		1310
961	my $signal = uc $arg{signal}	1311	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";	1312	or Carp::croak "required option 'signal' is missing";
963		1313
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1314	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1315
		1316	if ($HAVE_ASYNC_INTERRUPT) {
		1317	# async::interrupt
		1318
		1319	$SIG_ASY{$signal} ||= do {
		1320	my $asy = new Async::Interrupt
		1321	cb => sub { undef $SIG_EV{$signal} },
		1322	signal => $signal,
		1323	pipe => [$SIGPIPE_R->filenos],
		1324	;
		1325	$asy->pipe_autodrain (0);
		1326
		1327	$asy
		1328	};
		1329
		1330	} else {
		1331	# pure perl
		1332
965	$SIG{$signal} ||= sub {	1333	$SIG{$signal} ||= sub {
966	$_->() for values %{ $SIG_CB{$signal} || {} };	1334	local $!;
		1335	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1336	undef $SIG_EV{$signal};
		1337	};
		1338
		1339	# can't do signal processing without introducing races in pure perl,
		1340	# so limit the signal latency.
		1341	_sig_add;
967	};	1342	}
968		1343
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1344	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
970	}	1345	}
971		1346
		1347	sub signal {
		1348	# probe for availability of Async::Interrupt
		1349	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1350	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1351
		1352	$HAVE_ASYNC_INTERRUPT = 1;
		1353	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1354	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1355
		1356	} else {
		1357	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1358
		1359	require Fcntl;
		1360
		1361	if (AnyEvent::WIN32) {
		1362	require AnyEvent::Util;
		1363
		1364	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1366	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1367	} else {
		1368	pipe $SIGPIPE_R, $SIGPIPE_W;
		1369	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1370	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1371
		1372	# not strictly required, as $^F is normally 2, but let's make sure...
		1373	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1374	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1375	}
		1376
		1377	$SIGPIPE_R
		1378	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1379
		1380	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1381	}
		1382
		1383	*signal = \&_signal;
		1384	&signal
		1385	}
		1386
972	sub AnyEvent::Base::Signal::DESTROY {	1387	sub AnyEvent::Base::signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};	1388	my ($signal, $cb) = @{$_[0]};
974		1389
		1390	_sig_del;
		1391
975	delete $SIG_CB{$signal}{$cb};	1392	delete $SIG_CB{$signal}{$cb};
976		1393
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1394	$HAVE_ASYNC_INTERRUPT
		1395	? delete $SIG_ASY{$signal}
		1396	: # delete doesn't work with older perls - they then
		1397	# print weird messages, or just unconditionally exit
		1398	# instead of getting the default action.
		1399	undef $SIG{$signal}
		1400	unless keys %{ $SIG_CB{$signal} };
978	}	1401	}
979		1402
980	# default implementation for ->child	1403	# default implementation for ->child
981		1404
982	our %PID_CB;	1405	our %PID_CB;
983	our $CHLD_W;	1406	our $CHLD_W;
984	our $CHLD_DELAY_W;	1407	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;	1408	our $WNOHANG;
987		1409
988	sub _child_wait {	1410	sub _sigchld {
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1411	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1412	$_->($pid, $?)
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1413	for values %{ $PID_CB{$pid} || {} },
991	(values %{ $PID_CB{0} || {} });	1414	values %{ $PID_CB{0} || {} };
992	}	1415	}
993
994	undef $PID_IDLE;
995	}
996
997	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.
999	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1000	undef $CHLD_DELAY_W;
1001	&_child_wait;
1002	});
1003	}	1416	}
1004		1417
1005	sub child {	1418	sub child {
1006	my (undef, %arg) = @_;	1419	my (undef, %arg) = @_;
1007		1420
1008	defined (my $pid = $arg{pid} + 0)	1421	defined (my $pid = $arg{pid} + 0)
1009	or Carp::croak "required option 'pid' is missing";	1422	or Carp::croak "required option 'pid' is missing";
1010		1423
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1424	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1012		1425
1013	unless ($WNOHANG) {	1426	# WNOHANG is almost cetrainly 1 everywhere
		1427	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1428	? 1
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1429	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015	}
1016		1430
1017	unless ($CHLD_W) {	1431	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1432	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1019	# child could be a zombie already, so make at least one round	1433	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1434	&_sigchld;
1021	}	1435	}
1022		1436
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1437	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1024	}	1438	}
1025		1439
1026	sub AnyEvent::Base::Child::DESTROY {	1440	sub AnyEvent::Base::child::DESTROY {
1027	my ($pid, $cb) = @{$_[0]};	1441	my ($pid, $cb) = @{$_[0]};
1028		1442
1029	delete $PID_CB{$pid}{$cb};	1443	delete $PID_CB{$pid}{$cb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1444	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1445
1032	undef $CHLD_W unless keys %PID_CB;	1446	undef $CHLD_W unless keys %PID_CB;
1033	}	1447	}
1034		1448
		1449	# idle emulation is done by simply using a timer, regardless
		1450	# of whether the process is idle or not, and not letting
		1451	# the callback use more than 50% of the time.
		1452	sub idle {
		1453	my (undef, %arg) = @_;
		1454
		1455	my ($cb, $w, $rcb) = $arg{cb};
		1456
		1457	$rcb = sub {
		1458	if ($cb) {
		1459	$w = _time;
		1460	&$cb;
		1461	$w = _time - $w;
		1462
		1463	# never use more then 50% of the time for the idle watcher,
		1464	# within some limits
		1465	$w = 0.0001 if $w < 0.0001;
		1466	$w = 5 if $w > 5;
		1467
		1468	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1469	} else {
		1470	# clean up...
		1471	undef $w;
		1472	undef $rcb;
		1473	}
		1474	};
		1475
		1476	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1477
		1478	bless \\$cb, "AnyEvent::Base::idle"
		1479	}
		1480
		1481	sub AnyEvent::Base::idle::DESTROY {
		1482	undef $${$_[0]};
		1483	}
		1484
1035	package AnyEvent::CondVar;	1485	package AnyEvent::CondVar;
1036		1486
1037	our @ISA = AnyEvent::CondVar::Base::;	1487	our @ISA = AnyEvent::CondVar::Base::;
1038		1488
1039	package AnyEvent::CondVar::Base;	1489	package AnyEvent::CondVar::Base;
1040		1490
1041	use overload	1491	#use overload
1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1492	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1043	fallback => 1;	1493	# fallback => 1;
		1494
		1495	# save 300+ kilobytes by dirtily hardcoding overloading
		1496	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1497	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1498	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1499	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1500
		1501	our $WAITING;
1044		1502
1045	sub _send {	1503	sub _send {
1046	# nop	1504	# nop
1047	}	1505	}
1048		1506
…		…
1061	sub ready {	1519	sub ready {
1062	$_[0]{_ae_sent}	1520	$_[0]{_ae_sent}
1063	}	1521	}
1064		1522
1065	sub _wait {	1523	sub _wait {
		1524	$WAITING
		1525	and !$_[0]{_ae_sent}
		1526	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1527
		1528	local $WAITING = 1;
1066	AnyEvent->one_event while !$_[0]{_ae_sent};	1529	AnyEvent->one_event while !$_[0]{_ae_sent};
1067	}	1530	}
1068		1531
1069	sub recv {	1532	sub recv {
1070	$_[0]->_wait;	1533	$_[0]->_wait;
…		…
1089	}	1552	}
1090		1553
1091	# undocumented/compatibility with pre-3.4	1554	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	1555	*broadcast = \&send;
1093	*wait = \&_wait;	1556	*wait = \&_wait;
		1557
		1558	=head1 ERROR AND EXCEPTION HANDLING
		1559
		1560	In general, AnyEvent does not do any error handling - it relies on the
		1561	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1562	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1563	checking of all AnyEvent methods, however, which is highly useful during
		1564	development.
		1565
		1566	As for exception handling (i.e. runtime errors and exceptions thrown while
		1567	executing a callback), this is not only highly event-loop specific, but
		1568	also not in any way wrapped by this module, as this is the job of the main
		1569	program.
		1570
		1571	The pure perl event loop simply re-throws the exception (usually
		1572	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1573	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1574	so on.
		1575
		1576	=head1 ENVIRONMENT VARIABLES
		1577
		1578	The following environment variables are used by this module or its
		1579	submodules.
		1580
		1581	Note that AnyEvent will remove I<all> environment variables starting with
		1582	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1583	enabled.
		1584
		1585	=over 4
		1586
		1587	=item C<PERL_ANYEVENT_VERBOSE>
		1588
		1589	By default, AnyEvent will be completely silent except in fatal
		1590	conditions. You can set this environment variable to make AnyEvent more
		1591	talkative.
		1592
		1593	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1594	conditions, such as not being able to load the event model specified by
		1595	C<PERL_ANYEVENT_MODEL>.
		1596
		1597	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1598	model it chooses.
		1599
		1600	When set to C<8> or higher, then AnyEvent will report extra information on
		1601	which optional modules it loads and how it implements certain features.
		1602
		1603	=item C<PERL_ANYEVENT_STRICT>
		1604
		1605	AnyEvent does not do much argument checking by default, as thorough
		1606	argument checking is very costly. Setting this variable to a true value
		1607	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1608	check the arguments passed to most method calls. If it finds any problems,
		1609	it will croak.
		1610
		1611	In other words, enables "strict" mode.
		1612
		1613	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1614	>>, it is definitely recommended to keep it off in production. Keeping
		1615	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1616	can be very useful, however.
		1617
		1618	=item C<PERL_ANYEVENT_MODEL>
		1619
		1620	This can be used to specify the event model to be used by AnyEvent, before
		1621	auto detection and -probing kicks in. It must be a string consisting
		1622	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1623	and the resulting module name is loaded and if the load was successful,
		1624	used as event model. If it fails to load AnyEvent will proceed with
		1625	auto detection and -probing.
		1626
		1627	This functionality might change in future versions.
		1628
		1629	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1630	could start your program like this:
		1631
		1632	PERL_ANYEVENT_MODEL=Perl perl ...
		1633
		1634	=item C<PERL_ANYEVENT_PROTOCOLS>
		1635
		1636	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1637	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1638	of auto probing).
		1639
		1640	Must be set to a comma-separated list of protocols or address families,
		1641	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1642	used, and preference will be given to protocols mentioned earlier in the
		1643	list.
		1644
		1645	This variable can effectively be used for denial-of-service attacks
		1646	against local programs (e.g. when setuid), although the impact is likely
		1647	small, as the program has to handle conenction and other failures anyways.
		1648
		1649	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1650	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1651	- only support IPv4, never try to resolve or contact IPv6
		1652	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1653	IPv6, but prefer IPv6 over IPv4.
		1654
		1655	=item C<PERL_ANYEVENT_EDNS0>
		1656
		1657	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1658	for DNS. This extension is generally useful to reduce DNS traffic, but
		1659	some (broken) firewalls drop such DNS packets, which is why it is off by
		1660	default.
		1661
		1662	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1663	EDNS0 in its DNS requests.
		1664
		1665	=item C<PERL_ANYEVENT_MAX_FORKS>
		1666
		1667	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1668	will create in parallel.
		1669
		1670	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1671
		1672	The default value for the C<max_outstanding> parameter for the default DNS
		1673	resolver - this is the maximum number of parallel DNS requests that are
		1674	sent to the DNS server.
		1675
		1676	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1677
		1678	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1679	configuration) in the default resolver. When set to the empty string, no
		1680	default config will be used.
		1681
		1682	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1683
		1684	When neither C<ca_file> nor C<ca_path> was specified during
		1685	L<AnyEvent::TLS> context creation, and either of these environment
		1686	variables exist, they will be used to specify CA certificate locations
		1687	instead of a system-dependent default.
		1688
		1689	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1690
		1691	When these are set to C<1>, then the respective modules are not
		1692	loaded. Mostly good for testing AnyEvent itself.
		1693
		1694	=back
1094		1695
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1696	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		1697
1097	This is an advanced topic that you do not normally need to use AnyEvent in	1698	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	1699	a module. This section is only of use to event loop authors who want to
…		…
1132		1733
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1734	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	1735	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	1736	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.	1737	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		1738
1211	=head1 EXAMPLE PROGRAM	1739	=head1 EXAMPLE PROGRAM
1212		1740
1213	The following program uses an I/O watcher to read data from STDIN, a timer	1741	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	1742	to display a message once per second, and a condition variable to quit the
…		…
1408	watcher.	1936	watcher.
1409		1937
1410	=head3 Results	1938	=head3 Results
1411		1939
1412	name watchers bytes create invoke destroy comment	1940	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1941	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	1942	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	1943	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	1944	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	1945	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	1946	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1947	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1948	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	1949	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	1950	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	1951	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	1952	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1423		1953
1424	=head3 Discussion	1954	=head3 Discussion
1425		1955
1426	The benchmark does I<not> measure scalability of the event loop very	1956	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)	1957	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	1982	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.	1983	them active), of course, but this was not subject of this benchmark.
1454		1984
1455	The C<Event> module has a relatively high setup and callback invocation	1985	The C<Event> module has a relatively high setup and callback invocation
1456	cost, but overall scores in on the third place.	1986	cost, but overall scores in on the third place.
		1987
		1988	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1989	when using its pure perl backend.
1457		1990
1458	C<Glib>'s memory usage is quite a bit higher, but it features a	1991	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	1992	faster callback invocation and overall ends up in the same class as
1460	C<Event>. However, Glib scales extremely badly, doubling the number of	1993	C<Event>. However, Glib scales extremely badly, doubling the number of
1461	watchers increases the processing time by more than a factor of four,	1994	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	2072	it to another server. This includes deleting the old timeout and creating
1540	a new one that moves the timeout into the future.	2073	a new one that moves the timeout into the future.
1541		2074
1542	=head3 Results	2075	=head3 Results
1543		2076
1544	name sockets create request	2077	name sockets create request
1545	EV 20000 69.01 11.16	2078	EV 20000 69.01 11.16
1546	Perl 20000 73.32 35.87	2079	Perl 20000 73.32 35.87
		2080	IOAsync 20000 157.00 98.14 epoll
		2081	IOAsync 20000 159.31 616.06 poll
1547	Event 20000 212.62 257.32	2082	Event 20000 212.62 257.32
1548	Glib 20000 651.16 1896.30	2083	Glib 20000 651.16 1896.30
1549	POE 20000 349.67 12317.24 uses POE::Loop::Event	2084	POE 20000 349.67 12317.24 uses POE::Loop::Event
1550		2085
1551	=head3 Discussion	2086	=head3 Discussion
1552		2087
1553	This benchmark I<does> measure scalability and overall performance of the	2088	This benchmark I<does> measure scalability and overall performance of the
1554	particular event loop.	2089	particular event loop.
…		…
1556	EV is again fastest. Since it is using epoll on my system, the setup time	2091	EV is again fastest. Since it is using epoll on my system, the setup time
1557	is relatively high, though.	2092	is relatively high, though.
1558		2093
1559	Perl surprisingly comes second. It is much faster than the C-based event	2094	Perl surprisingly comes second. It is much faster than the C-based event
1560	loops Event and Glib.	2095	loops Event and Glib.
		2096
		2097	IO::Async performs very well when using its epoll backend, and still quite
		2098	good compared to Glib when using its pure perl backend.
1561		2099
1562	Event suffers from high setup time as well (look at its code and you will	2100	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	2101	understand why). Callback invocation also has a high overhead compared to
1564	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2102	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565	uses select or poll in basically all documented configurations.	2103	uses select or poll in basically all documented configurations.
…		…
1628	=item * C-based event loops perform very well with small number of	2166	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	2167	watchers, as the management overhead dominates.
1630		2168
1631	=back	2169	=back
1632		2170
		2171	=head2 THE IO::Lambda BENCHMARK
		2172
		2173	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2174	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2175	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2176	shouldn't come as a surprise to anybody). As such, the benchmark is
		2177	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2178	very optimal. But how would AnyEvent compare when used without the extra
		2179	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2180
		2181	The benchmark itself creates an echo-server, and then, for 500 times,
		2182	connects to the echo server, sends a line, waits for the reply, and then
		2183	creates the next connection. This is a rather bad benchmark, as it doesn't
		2184	test the efficiency of the framework or much non-blocking I/O, but it is a
		2185	benchmark nevertheless.
		2186
		2187	name runtime
		2188	Lambda/select 0.330 sec
		2189	+ optimized 0.122 sec
		2190	Lambda/AnyEvent 0.327 sec
		2191	+ optimized 0.138 sec
		2192	Raw sockets/select 0.077 sec
		2193	POE/select, components 0.662 sec
		2194	POE/select, raw sockets 0.226 sec
		2195	POE/select, optimized 0.404 sec
		2196
		2197	AnyEvent/select/nb 0.085 sec
		2198	AnyEvent/EV/nb 0.068 sec
		2199	+state machine 0.134 sec
		2200
		2201	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2202	benchmarks actually make blocking connects and use 100% blocking I/O,
		2203	defeating the purpose of an event-based solution. All of the newly
		2204	written AnyEvent benchmarks use 100% non-blocking connects (using
		2205	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2206	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2207	generally require a lot more bookkeeping and event handling than blocking
		2208	connects (which involve a single syscall only).
		2209
		2210	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2211	offers similar expressive power as POE and IO::Lambda, using conventional
		2212	Perl syntax. This means that both the echo server and the client are 100%
		2213	non-blocking, further placing it at a disadvantage.
		2214
		2215	As you can see, the AnyEvent + EV combination even beats the
		2216	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2217	backend easily beats IO::Lambda and POE.
		2218
		2219	And even the 100% non-blocking version written using the high-level (and
		2220	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2221	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2222	in a non-blocking way.
		2223
		2224	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2225	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2226	part of the IO::lambda distribution and were used without any changes.
		2227
		2228
		2229	=head1 SIGNALS
		2230
		2231	AnyEvent currently installs handlers for these signals:
		2232
		2233	=over 4
		2234
		2235	=item SIGCHLD
		2236
		2237	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2238	emulation for event loops that do not support them natively. Also, some
		2239	event loops install a similar handler.
		2240
		2241	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2242	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2243
		2244	=item SIGPIPE
		2245
		2246	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2247	when AnyEvent gets loaded.
		2248
		2249	The rationale for this is that AnyEvent users usually do not really depend
		2250	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2251	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2252	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2253	some random socket.
		2254
		2255	The rationale for installing a no-op handler as opposed to ignoring it is
		2256	that this way, the handler will be restored to defaults on exec.
		2257
		2258	Feel free to install your own handler, or reset it to defaults.
		2259
		2260	=back
		2261
		2262	=cut
		2263
		2264	undef $SIG{CHLD}
		2265	if $SIG{CHLD} eq 'IGNORE';
		2266
		2267	$SIG{PIPE} = sub { }
		2268	unless defined $SIG{PIPE};
		2269
		2270	=head1 RECOMMENDED/OPTIONAL MODULES
		2271
		2272	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2273	it's built-in modules) are required to use it.
		2274
		2275	That does not mean that AnyEvent won't take advantage of some additional
		2276	modules if they are installed.
		2277
		2278	This section epxlains which additional modules will be used, and how they
		2279	affect AnyEvent's operetion.
		2280
		2281	=over 4
		2282
		2283	=item L<Async::Interrupt>
		2284
		2285	This slightly arcane module is used to implement fast signal handling: To
		2286	my knowledge, there is no way to do completely race-free and quick
		2287	signal handling in pure perl. To ensure that signals still get
		2288	delivered, AnyEvent will start an interval timer to wake up perl (and
		2289	catch the signals) with some delay (default is 10 seconds, look for
		2290	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2291
		2292	If this module is available, then it will be used to implement signal
		2293	catching, which means that signals will not be delayed, and the event loop
		2294	will not be interrupted regularly, which is more efficient (And good for
		2295	battery life on laptops).
		2296
		2297	This affects not just the pure-perl event loop, but also other event loops
		2298	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2299
		2300	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2301	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2302	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2303	does nothing for those backends.
		2304
		2305	=item L<EV>
		2306
		2307	This module isn't really "optional", as it is simply one of the backend
		2308	event loops that AnyEvent can use. However, it is simply the best event
		2309	loop available in terms of features, speed and stability: It supports
		2310	the AnyEvent API optimally, implements all the watcher types in XS, does
		2311	automatic timer adjustments even when no monotonic clock is available,
		2312	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2313	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2314	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2315
		2316	=item L<Guard>
		2317
		2318	The guard module, when used, will be used to implement
		2319	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2320	lot less memory), but otherwise doesn't affect guard operation much. It is
		2321	purely used for performance.
		2322
		2323	=item L<JSON> and L<JSON::XS>
		2324
		2325	This module is required when you want to read or write JSON data via
		2326	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2327	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2328
		2329	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2330	installed.
		2331
		2332	=item L<Net::SSLeay>
		2333
		2334	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2335	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2336	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2337
		2338	=item L<Time::HiRes>
		2339
		2340	This module is part of perl since release 5.008. It will be used when the
		2341	chosen event library does not come with a timing source on it's own. The
		2342	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2343	try to use a monotonic clock for timing stability.
		2344
		2345	=back
		2346
1633		2347
1634	=head1 FORK	2348	=head1 FORK
1635		2349
1636	Most event libraries are not fork-safe. The ones who are usually are	2350	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>	2351	because they rely on inefficient but fork-safe C<select> or C<poll>
1638	calls. Only L<EV> is fully fork-aware.	2352	calls. Only L<EV> is fully fork-aware.
1639		2353
1640	If you have to fork, you must either do so I<before> creating your first	2354	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.	2355	watcher OR you must not use AnyEvent at all in the child OR you must do
		2356	something completely out of the scope of AnyEvent.
1642		2357
1643		2358
1644	=head1 SECURITY CONSIDERATIONS	2359	=head1 SECURITY CONSIDERATIONS
1645		2360
1646	AnyEvent can be forced to load any event model via	2361	AnyEvent can be forced to load any event model via
…		…
1651	specified in the variable.	2366	specified in the variable.
1652		2367
1653	You can make AnyEvent completely ignore this variable by deleting it	2368	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:	2369	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2370
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2371	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2372
1658	use AnyEvent;	2373	use AnyEvent;
1659		2374
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2375	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	2376	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).	2377	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2378	$ENV{PERL_ANYEVENT_STRICT}.
		2379
		2380	Note that AnyEvent will remove I<all> environment variables starting with
		2381	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2382	enabled.
		2383
		2384
		2385	=head1 BUGS
		2386
		2387	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2388	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2389	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2390	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2391	pronounced).
1663		2392
1664		2393
1665	=head1 SEE ALSO	2394	=head1 SEE ALSO
1666		2395
1667	Utility functions: L<AnyEvent::Util>.	2396	Utility functions: L<AnyEvent::Util>.
…		…
1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2399	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1671		2400
1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2401	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2402	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2403	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1675	L<AnyEvent::Impl::POE>.	2404	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1676		2405
1677	Non-blocking file handles, sockets, TCP clients and	2406	Non-blocking file handles, sockets, TCP clients and
1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2407	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1679		2408
1680	Asynchronous DNS: L<AnyEvent::DNS>.	2409	Asynchronous DNS: L<AnyEvent::DNS>.
1681		2410
1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2411	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2412	L<Coro::Event>,
1683		2413
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2414	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2415	L<AnyEvent::HTTP>.
1685		2416
1686		2417
1687	=head1 AUTHOR	2418	=head1 AUTHOR
1688		2419
1689	Marc Lehmann <schmorp@schmorp.de>	2420	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	2421	http://home.schmorp.de/
1691		2422
1692	=cut	2423	=cut
1693		2424
1694	1	2425	1
1695		2426

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