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Comparing AnyEvent/README (file contents):
Revision 1.28 by root, Sat Jul 12 20:45:27 2008 UTC vs.
Revision 1.51 by root, Sun Aug 9 16:05:11 2009 UTC

…		…
1	NAME	1	NAME
2	AnyEvent - provide framework for multiple event loops	2	AnyEvent - the DBI of event loop programming
3		3
4	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event	4	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5	loops	5	Qt and POE are various supported event loops/environments.
6		6
7	SYNOPSIS	7	SYNOPSIS
8	use AnyEvent;	8	use AnyEvent;
9		9
		10	# file descriptor readable
10	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		12
		13	# one-shot or repeating timers
		14	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		15	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		16
		17	print AnyEvent->now; # prints current event loop time
		18	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		19
		20	# POSIX signal
		21	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		22
		23	# child process exit
		24	my $w = AnyEvent->child (pid => $pid, cb => sub {
		25	my ($pid, $status) = @_;
11	...	26	...
12	});	27	});
13		28
14	my $w = AnyEvent->timer (after => $seconds, cb => sub {	29	# called when event loop idle (if applicable)
15	...	30	my $w = AnyEvent->idle (cb => sub { ... });
16	});
17		31
18	my $w = AnyEvent->condvar; # stores whether a condition was flagged	32	my $w = AnyEvent->condvar; # stores whether a condition was flagged
19	$w->send; # wake up current and all future recv's	33	$w->send; # wake up current and all future recv's
20	$w->recv; # enters "main loop" till $condvar gets ->send	34	$w->recv; # enters "main loop" till $condvar gets ->send
		35	# use a condvar in callback mode:
		36	$w->cb (sub { $_[0]->recv });
21		37
22	INTRODUCTION/TUTORIAL	38	INTRODUCTION/TUTORIAL
23	This manpage is mainly a reference manual. If you are interested in a	39	This manpage is mainly a reference manual. If you are interested in a
24	tutorial or some gentle introduction, have a look at the AnyEvent::Intro	40	tutorial or some gentle introduction, have a look at the AnyEvent::Intro
25	manpage.	41	manpage.
		42
		43	SUPPORT
		44	There is a mailinglist for discussing all things AnyEvent, and an IRC
		45	channel, too.
		46
		47	See the AnyEvent project page at the Schmorpforge Ta-Sa Software
		48	Repository, at <http://anyevent.schmorp.de>, for more info.
26		49
27	WHY YOU SHOULD USE THIS MODULE (OR NOT)	50	WHY YOU SHOULD USE THIS MODULE (OR NOT)
28	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	51	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
29	nowadays. So what is different about AnyEvent?	52	nowadays. So what is different about AnyEvent?
30		53
123	These watchers are normal Perl objects with normal Perl lifetime. After	146	These watchers are normal Perl objects with normal Perl lifetime. After
124	creating a watcher it will immediately "watch" for events and invoke the	147	creating a watcher it will immediately "watch" for events and invoke the
125	callback when the event occurs (of course, only when the event model is	148	callback when the event occurs (of course, only when the event model is
126	in control).	149	in control).
127		150
		151	Note that callbacks must not permanently change global variables
		152	potentially in use by the event loop (such as $_ or $[) and that
		153	callbacks must not "die". The former is good programming practise in
		154	Perl and the latter stems from the fact that exception handling differs
		155	widely between event loops.
		156
128	To disable the watcher you have to destroy it (e.g. by setting the	157	To disable the watcher you have to destroy it (e.g. by setting the
129	variable you store it in to "undef" or otherwise deleting all references	158	variable you store it in to "undef" or otherwise deleting all references
130	to it).	159	to it).
131		160
132	All watchers are created by calling a method on the "AnyEvent" class.	161	All watchers are created by calling a method on the "AnyEvent" class.
…		…
144	Note that "my $w; $w =" combination. This is necessary because in Perl,	173	Note that "my $w; $w =" combination. This is necessary because in Perl,
145	my variables are only visible after the statement in which they are	174	my variables are only visible after the statement in which they are
146	declared.	175	declared.
147		176
148	I/O WATCHERS	177	I/O WATCHERS
		178	$w = AnyEvent->io (
		179	fh => <filehandle_or_fileno>,
		180	poll => <"r" or "w">,
		181	cb => <callback>,
		182	);
		183
149	You can create an I/O watcher by calling the "AnyEvent->io" method with	184	You can create an I/O watcher by calling the "AnyEvent->io" method with
150	the following mandatory key-value pairs as arguments:	185	the following mandatory key-value pairs as arguments:
151		186
152	"fh" the Perl file handle (not file descriptor) to watch for events	187	"fh" is the Perl file handle (or a naked file descriptor) to watch for
153	(AnyEvent might or might not keep a reference to this file handle).	188	events (AnyEvent might or might not keep a reference to this file
		189	handle). Note that only file handles pointing to things for which
		190	non-blocking operation makes sense are allowed. This includes sockets,
		191	most character devices, pipes, fifos and so on, but not for example
		192	files or block devices.
		193
154	"poll" must be a string that is either "r" or "w", which creates a	194	"poll" must be a string that is either "r" or "w", which creates a
155	watcher waiting for "r"eadable or "w"ritable events, respectively. "cb"	195	watcher waiting for "r"eadable or "w"ritable events, respectively.
		196
156	is the callback to invoke each time the file handle becomes ready.	197	"cb" is the callback to invoke each time the file handle becomes ready.
157		198
158	Although the callback might get passed parameters, their value and	199	Although the callback might get passed parameters, their value and
159	presence is undefined and you cannot rely on them. Portable AnyEvent	200	presence is undefined and you cannot rely on them. Portable AnyEvent
160	callbacks cannot use arguments passed to I/O watcher callbacks.	201	callbacks cannot use arguments passed to I/O watcher callbacks.
161		202
…		…
175	warn "read: $input\n";	216	warn "read: $input\n";
176	undef $w;	217	undef $w;
177	});	218	});
178		219
179	TIME WATCHERS	220	TIME WATCHERS
		221	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		222
		223	$w = AnyEvent->timer (
		224	after => <fractional_seconds>,
		225	interval => <fractional_seconds>,
		226	cb => <callback>,
		227	);
		228
180	You can create a time watcher by calling the "AnyEvent->timer" method	229	You can create a time watcher by calling the "AnyEvent->timer" method
181	with the following mandatory arguments:	230	with the following mandatory arguments:
182		231
183	"after" specifies after how many seconds (fractional values are	232	"after" specifies after how many seconds (fractional values are
184	supported) the callback should be invoked. "cb" is the callback to	233	supported) the callback should be invoked. "cb" is the callback to
…		…
293	In either case, if you care (and in most cases, you don't), then you	342	In either case, if you care (and in most cases, you don't), then you
294	can get whatever behaviour you want with any event loop, by taking	343	can get whatever behaviour you want with any event loop, by taking
295	the difference between "AnyEvent->time" and "AnyEvent->now" into	344	the difference between "AnyEvent->time" and "AnyEvent->now" into
296	account.	345	account.
297		346
		347	AnyEvent->now_update
		348	Some event loops (such as EV or AnyEvent::Impl::Perl) cache the
		349	current time for each loop iteration (see the discussion of
		350	AnyEvent->now, above).
		351
		352	When a callback runs for a long time (or when the process sleeps),
		353	then this "current" time will differ substantially from the real
		354	time, which might affect timers and time-outs.
		355
		356	When this is the case, you can call this method, which will update
		357	the event loop's idea of "current time".
		358
		359	Note that updating the time might cause some events to be handled.
		360
298	SIGNAL WATCHERS	361	SIGNAL WATCHERS
		362	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		363
299	You can watch for signals using a signal watcher, "signal" is the signal	364	You can watch for signals using a signal watcher, "signal" is the signal
300	name in uppercase and without any "SIG" prefix, "cb" is the Perl	365	name in uppercase and without any "SIG" prefix, "cb" is the Perl
301	callback to be invoked whenever a signal occurs.	366	callback to be invoked whenever a signal occurs.
302		367
303	Although the callback might get passed parameters, their value and	368	Although the callback might get passed parameters, their value and
…		…
308	invocation, and callback invocation will be synchronous. Synchronous	373	invocation, and callback invocation will be synchronous. Synchronous
309	means that it might take a while until the signal gets handled by the	374	means that it might take a while until the signal gets handled by the
310	process, but it is guaranteed not to interrupt any other callbacks.	375	process, but it is guaranteed not to interrupt any other callbacks.
311		376
312	The main advantage of using these watchers is that you can share a	377	The main advantage of using these watchers is that you can share a
313	signal between multiple watchers.	378	signal between multiple watchers, and AnyEvent will ensure that signals
		379	will not interrupt your program at bad times.
314		380
315	This watcher might use %SIG, so programs overwriting those signals	381	This watcher might use %SIG (depending on the event loop used), so
316	directly will likely not work correctly.	382	programs overwriting those signals directly will likely not work
		383	correctly.
317		384
318	Example: exit on SIGINT	385	Example: exit on SIGINT
319		386
320	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	387	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
321		388
		389	Signal Races, Delays and Workarounds
		390	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		391	callbacks to signals in a generic way, which is a pity, as you cannot do
		392	race-free signal handling in perl, requiring C libraries for this.
		393	AnyEvent will try to do it's best, which means in some cases, signals
		394	will be delayed. The maximum time a signal might be delayed is specified
		395	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
		396	can be changed only before the first signal watcher is created, and
		397	should be left alone otherwise. This variable determines how often
		398	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		399	will cause fewer spurious wake-ups, which is better for power and CPU
		400	saving.
		401
		402	All these problems can be avoided by installing the optional
		403	Async::Interrupt module, which works with most event loops. It will not
		404	work with inherently broken event loops such as Event or Event::Lib (and
		405	not with POE currently, as POE does it's own workaround with one-second
		406	latency). For those, you just have to suffer the delays.
		407
322	CHILD PROCESS WATCHERS	408	CHILD PROCESS WATCHERS
		409	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		410
323	You can also watch on a child process exit and catch its exit status.	411	You can also watch on a child process exit and catch its exit status.
324		412
325	The child process is specified by the "pid" argument (if set to 0, it	413	The child process is specified by the "pid" argument (one some backends,
326	watches for any child process exit). The watcher will trigger as often	414	using 0 watches for any child process exit, on others this will croak).
327	as status change for the child are received. This works by installing a	415	The watcher will be triggered only when the child process has finished
328	signal handler for "SIGCHLD". The callback will be called with the pid	416	and an exit status is available, not on any trace events
329	and exit status (as returned by waitpid), so unlike other watcher types,	417	(stopped/continued).
330	you can rely on child watcher callback arguments.	418
		419	The callback will be called with the pid and exit status (as returned by
		420	waitpid), so unlike other watcher types, you can rely on child watcher
		421	callback arguments.
		422
		423	This watcher type works by installing a signal handler for "SIGCHLD",
		424	and since it cannot be shared, nothing else should use SIGCHLD or reap
		425	random child processes (waiting for specific child processes, e.g.
		426	inside "system", is just fine).
331		427
332	There is a slight catch to child watchers, however: you usually start	428	There is a slight catch to child watchers, however: you usually start
333	them after the child process was created, and this means the process	429	them after the child process was created, and this means the process
334	could have exited already (and no SIGCHLD will be sent anymore).	430	could have exited already (and no SIGCHLD will be sent anymore).
335		431
336	Not all event models handle this correctly (POE doesn't), but even for	432	Not all event models handle this correctly (neither POE nor IO::Async
		433	do, see their AnyEvent::Impl manpages for details), but even for event
337	event models that do handle this correctly, they usually need to be	434	models that do handle this correctly, they usually need to be loaded
338	loaded before the process exits (i.e. before you fork in the first	435	before the process exits (i.e. before you fork in the first place).
339	place).	436	AnyEvent's pure perl event loop handles all cases correctly regardless
		437	of when you start the watcher.
340		438
341	This means you cannot create a child watcher as the very first thing in	439	This means you cannot create a child watcher as the very first thing in
342	an AnyEvent program, you have to create at least one watcher before	440	an AnyEvent program, you have to create at least one watcher before
343	you "fork" the child (alternatively, you can call "AnyEvent::detect").	441	you "fork" the child (alternatively, you can call "AnyEvent::detect").
344		442
		443	As most event loops do not support waiting for child events, they will
		444	be emulated by AnyEvent in most cases, in which the latency and race
		445	problems mentioned in the description of signal watchers apply.
		446
345	Example: fork a process and wait for it	447	Example: fork a process and wait for it
346		448
347	my $done = AnyEvent->condvar;	449	my $done = AnyEvent->condvar;
348		450
349	my $pid = fork or exit 5;	451	my $pid = fork or exit 5;
350		452
351	my $w = AnyEvent->child (	453	my $w = AnyEvent->child (
352	pid => $pid,	454	pid => $pid,
353	cb => sub {	455	cb => sub {
354	my ($pid, $status) = @_;	456	my ($pid, $status) = @_;
355	warn "pid $pid exited with status $status";	457	warn "pid $pid exited with status $status";
356	$done->send;	458	$done->send;
357	},	459	},
358	);	460	);
359		461
360	# do something else, then wait for process exit	462	# do something else, then wait for process exit
361	$done->recv;	463	$done->recv;
362		464
		465	IDLE WATCHERS
		466	$w = AnyEvent->idle (cb => <callback>);
		467
		468	Sometimes there is a need to do something, but it is not so important to
		469	do it instantly, but only when there is nothing better to do. This
		470	"nothing better to do" is usually defined to be "no other events need
		471	attention by the event loop".
		472
		473	Idle watchers ideally get invoked when the event loop has nothing better
		474	to do, just before it would block the process to wait for new events.
		475	Instead of blocking, the idle watcher is invoked.
		476
		477	Most event loops unfortunately do not really support idle watchers (only
		478	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		479	will simply call the callback "from time to time".
		480
		481	Example: read lines from STDIN, but only process them when the program
		482	is otherwise idle:
		483
		484	my @lines; # read data
		485	my $idle_w;
		486	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		487	push @lines, scalar <STDIN>;
		488
		489	# start an idle watcher, if not already done
		490	$idle_w \|\|= AnyEvent->idle (cb => sub {
		491	# handle only one line, when there are lines left
		492	if (my $line = shift @lines) {
		493	print "handled when idle: $line";
		494	} else {
		495	# otherwise disable the idle watcher again
		496	undef $idle_w;
		497	}
		498	});
		499	});
		500
363	CONDITION VARIABLES	501	CONDITION VARIABLES
		502	$cv = AnyEvent->condvar;
		503
		504	$cv->send (<list>);
		505	my @res = $cv->recv;
		506
364	If you are familiar with some event loops you will know that all of them	507	If you are familiar with some event loops you will know that all of them
365	require you to run some blocking "loop", "run" or similar function that	508	require you to run some blocking "loop", "run" or similar function that
366	will actively watch for new events and call your callbacks.	509	will actively watch for new events and call your callbacks.
367		510
368	AnyEvent is different, it expects somebody else to run the event loop	511	AnyEvent is slightly different: it expects somebody else to run the
369	and will only block when necessary (usually when told by the user).	512	event loop and will only block when necessary (usually when told by the
		513	user).
370		514
371	The instrument to do that is called a "condition variable", so called	515	The instrument to do that is called a "condition variable", so called
372	because they represent a condition that must become true.	516	because they represent a condition that must become true.
		517
		518	Now is probably a good time to look at the examples further below.
373		519
374	Condition variables can be created by calling the "AnyEvent->condvar"	520	Condition variables can be created by calling the "AnyEvent->condvar"
375	method, usually without arguments. The only argument pair allowed is	521	method, usually without arguments. The only argument pair allowed is
376	"cb", which specifies a callback to be called when the condition	522	"cb", which specifies a callback to be called when the condition
377	variable becomes true.	523	variable becomes true, with the condition variable as the first argument
		524	(but not the results).
378		525
379	After creation, the condition variable is "false" until it becomes	526	After creation, the condition variable is "false" until it becomes
380	"true" by calling the "send" method (or calling the condition variable	527	"true" by calling the "send" method (or calling the condition variable
381	as if it were a callback, read about the caveats in the description for	528	as if it were a callback, read about the caveats in the description for
382	the "->send" method).	529	the "->send" method).
…		…
384	Condition variables are similar to callbacks, except that you can	531	Condition variables are similar to callbacks, except that you can
385	optionally wait for them. They can also be called merge points - points	532	optionally wait for them. They can also be called merge points - points
386	in time where multiple outstanding events have been processed. And yet	533	in time where multiple outstanding events have been processed. And yet
387	another way to call them is transactions - each condition variable can	534	another way to call them is transactions - each condition variable can
388	be used to represent a transaction, which finishes at some point and	535	be used to represent a transaction, which finishes at some point and
389	delivers a result.	536	delivers a result. And yet some people know them as "futures" - a
		537	promise to compute/deliver something that you can wait for.
390		538
391	Condition variables are very useful to signal that something has	539	Condition variables are very useful to signal that something has
392	finished, for example, if you write a module that does asynchronous http	540	finished, for example, if you write a module that does asynchronous http
393	requests, then a condition variable would be the ideal candidate to	541	requests, then a condition variable would be the ideal candidate to
394	signal the availability of results. The user can either act when the	542	signal the availability of results. The user can either act when the
…		…
428	after => 1,	576	after => 1,
429	cb => sub { $result_ready->send },	577	cb => sub { $result_ready->send },
430	);	578	);
431		579
432	# this "blocks" (while handling events) till the callback	580	# this "blocks" (while handling events) till the callback
433	# calls send	581	# calls -<send
434	$result_ready->recv;	582	$result_ready->recv;
435		583
436	Example: wait for a timer, but take advantage of the fact that condition	584	Example: wait for a timer, but take advantage of the fact that condition
437	variables are also code references.	585	variables are also callable directly.
438		586
439	my $done = AnyEvent->condvar;	587	my $done = AnyEvent->condvar;
440	my $delay = AnyEvent->timer (after => 5, cb => $done);	588	my $delay = AnyEvent->timer (after => 5, cb => $done);
441	$done->recv;	589	$done->recv;
		590
		591	Example: Imagine an API that returns a condvar and doesn't support
		592	callbacks. This is how you make a synchronous call, for example from the
		593	main program:
		594
		595	use AnyEvent::CouchDB;
		596
		597	...
		598
		599	my @info = $couchdb->info->recv;
		600
		601	And this is how you would just set a callback to be called whenever the
		602	results are available:
		603
		604	$couchdb->info->cb (sub {
		605	my @info = $_[0]->recv;
		606	});
442		607
443	METHODS FOR PRODUCERS	608	METHODS FOR PRODUCERS
444	These methods should only be used by the producing side, i.e. the	609	These methods should only be used by the producing side, i.e. the
445	code/module that eventually sends the signal. Note that it is also the	610	code/module that eventually sends the signal. Note that it is also the
446	producer side which creates the condvar in most cases, but it isn't	611	producer side which creates the condvar in most cases, but it isn't
…		…
456		621
457	Any arguments passed to the "send" call will be returned by all	622	Any arguments passed to the "send" call will be returned by all
458	future "->recv" calls.	623	future "->recv" calls.
459		624
460	Condition variables are overloaded so one can call them directly (as	625	Condition variables are overloaded so one can call them directly (as
461	a code reference). Calling them directly is the same as calling	626	if they were a code reference). Calling them directly is the same as
462	"send". Note, however, that many C-based event loops do not handle	627	calling "send".
463	overloading, so as tempting as it may be, passing a condition
464	variable instead of a callback does not work. Both the pure perl and
465	EV loops support overloading, however, as well as all functions that
466	use perl to invoke a callback (as in AnyEvent::Socket and
467	AnyEvent::DNS for example).
468		628
469	$cv->croak ($error)	629	$cv->croak ($error)
470	Similar to send, but causes all call's to "->recv" to invoke	630	Similar to send, but causes all call's to "->recv" to invoke
471	"Carp::croak" with the given error message/object/scalar.	631	"Carp::croak" with the given error message/object/scalar.
472		632
473	This can be used to signal any errors to the condition variable	633	This can be used to signal any errors to the condition variable
474	user/consumer.	634	user/consumer. Doing it this way instead of calling "croak" directly
		635	delays the error detetcion, but has the overwhelmign advantage that
		636	it diagnoses the error at the place where the result is expected,
		637	and not deep in some event clalback without connection to the actual
		638	code causing the problem.
475		639
476	$cv->begin ([group callback])	640	$cv->begin ([group callback])
477	$cv->end	641	$cv->end
478	These two methods are EXPERIMENTAL and MIGHT CHANGE.
479
480	These two methods can be used to combine many transactions/events	642	These two methods can be used to combine many transactions/events
481	into one. For example, a function that pings many hosts in parallel	643	into one. For example, a function that pings many hosts in parallel
482	might want to use a condition variable for the whole process.	644	might want to use a condition variable for the whole process.
483		645
484	Every call to "->begin" will increment a counter, and every call to	646	Every call to "->begin" will increment a counter, and every call to
485	"->end" will decrement it. If the counter reaches 0 in "->end", the	647	"->end" will decrement it. If the counter reaches 0 in "->end", the
486	(last) callback passed to "begin" will be executed. That callback is	648	(last) callback passed to "begin" will be executed. That callback is
487	supposed to call "->send", but that is not required. If no	649	supposed to call "->send", but that is not required. If no
488	callback was set, "send" will be called without any arguments.	650	callback was set, "send" will be called without any arguments.
489		651
490	Let's clarify this with the ping example:	652	You can think of "$cv->send" giving you an OR condition (one call
		653	sends), while "$cv->begin" and "$cv->end" giving you an AND
		654	condition (all "begin" calls must be "end"'ed before the condvar
		655	sends).
		656
		657	Let's start with a simple example: you have two I/O watchers (for
		658	example, STDOUT and STDERR for a program), and you want to wait for
		659	both streams to close before activating a condvar:
		660
		661	my $cv = AnyEvent->condvar;
		662
		663	$cv->begin; # first watcher
		664	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		665	defined sysread $fh1, my $buf, 4096
		666	or $cv->end;
		667	});
		668
		669	$cv->begin; # second watcher
		670	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		671	defined sysread $fh2, my $buf, 4096
		672	or $cv->end;
		673	});
		674
		675	$cv->recv;
		676
		677	This works because for every event source (EOF on file handle),
		678	there is one call to "begin", so the condvar waits for all calls to
		679	"end" before sending.
		680
		681	The ping example mentioned above is slightly more complicated, as
		682	the there are results to be passwd back, and the number of tasks
		683	that are begung can potentially be zero:
491		684
492	my $cv = AnyEvent->condvar;	685	my $cv = AnyEvent->condvar;
493		686
494	my %result;	687	my %result;
495	$cv->begin (sub { $cv->send (\%result) });	688	$cv->begin (sub { $cv->send (\%result) });
…		…
515	the loop, which serves two important purposes: first, it sets the	708	the loop, which serves two important purposes: first, it sets the
516	callback to be called once the counter reaches 0, and second, it	709	callback to be called once the counter reaches 0, and second, it
517	ensures that "send" is called even when "no" hosts are being pinged	710	ensures that "send" is called even when "no" hosts are being pinged
518	(the loop doesn't execute once).	711	(the loop doesn't execute once).
519		712
520	This is the general pattern when you "fan out" into multiple	713	This is the general pattern when you "fan out" into multiple (but
521	subrequests: use an outer "begin"/"end" pair to set the callback and	714	potentially none) subrequests: use an outer "begin"/"end" pair to
522	ensure "end" is called at least once, and then, for each subrequest	715	set the callback and ensure "end" is called at least once, and then,
523	you start, call "begin" and for each subrequest you finish, call	716	for each subrequest you start, call "begin" and for each subrequest
524	"end".	717	you finish, call "end".
525		718
526	METHODS FOR CONSUMERS	719	METHODS FOR CONSUMERS
527	These methods should only be used by the consuming side, i.e. the code	720	These methods should only be used by the consuming side, i.e. the code
528	awaits the condition.	721	awaits the condition.
529		722
…		…
538	function will call "croak".	731	function will call "croak".
539		732
540	In list context, all parameters passed to "send" will be returned,	733	In list context, all parameters passed to "send" will be returned,
541	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
542		735
		736	Note that doing a blocking wait in a callback is not supported by
		737	any event loop, that is, recursive invocation of a blocking "->recv"
		738	is not allowed, and the "recv" call will "croak" if such a condition
		739	is detected. This condition can be slightly loosened by using
		740	Coro::AnyEvent, which allows you to do a blocking "->recv" from any
		741	thread that doesn't run the event loop itself.
		742
543	Not all event models support a blocking wait - some die in that case	743	Not all event models support a blocking wait - some die in that case
544	(programs might want to do that to stay interactive), so *if you are	744	(programs might want to do that to stay interactive), so *if you are
545	using this from a module, never require a blocking wait*, but let	745	using this from a module, never require a blocking wait*. Instead,
546	the caller decide whether the call will block or not (for example,	746	let the caller decide whether the call will block or not (for
547	by coupling condition variables with some kind of request results	747	example, by coupling condition variables with some kind of request
548	and supporting callbacks so the caller knows that getting the result	748	results and supporting callbacks so the caller knows that getting
549	will not block, while still supporting blocking waits if the caller	749	the result will not block, while still supporting blocking waits if
550	so desires).	750	the caller so desires).
551
552	Another reason never to "->recv" in a module is that you cannot
553	sensibly have two "->recv"'s in parallel, as that would require
554	multiple interpreters or coroutines/threads, none of which
555	"AnyEvent" can supply.
556
557	The Coro module, however, can and does supply coroutines and, in
558	fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe
559	versions and also integrates coroutines into AnyEvent, making
560	blocking "->recv" calls perfectly safe as long as they are done from
561	another coroutine (one that doesn't run the event loop).
562		751
563	You can ensure that "-recv" never blocks by setting a callback and	752	You can ensure that "-recv" never blocks by setting a callback and
564	only calling "->recv" from within that callback (or at a later	753	only calling "->recv" from within that callback (or at a later
565	time). This will work even when the event loop does not support	754	time). This will work even when the event loop does not support
566	blocking waits otherwise.	755	blocking waits otherwise.
567		756
568	$bool = $cv->ready	757	$bool = $cv->ready
569	Returns true when the condition is "true", i.e. whether "send" or	758	Returns true when the condition is "true", i.e. whether "send" or
570	"croak" have been called.	759	"croak" have been called.
571		760
572	$cb = $cv->cb ([new callback])	761	$cb = $cv->cb ($cb->($cv))
573	This is a mutator function that returns the callback set and	762	This is a mutator function that returns the callback set and
574	optionally replaces it before doing so.	763	optionally replaces it before doing so.
575		764
576	The callback will be called when the condition becomes "true", i.e.	765	The callback will be called when the condition becomes (or already
577	when "send" or "croak" are called, with the only argument being the	766	was) "true", i.e. when "send" or "croak" are called (or were
578	condition variable itself. Calling "recv" inside the callback or at	767	called), with the only argument being the condition variable itself.
		768	Calling "recv" inside the callback or at any later time is
579	any later time is guaranteed not to block.	769	guaranteed not to block.
		770
		771	SUPPORTED EVENT LOOPS/BACKENDS
		772	The available backend classes are (every class has its own manpage):
		773
		774	Backends that are autoprobed when no other event loop can be found.
		775	EV is the preferred backend when no other event loop seems to be in
		776	use. If EV is not installed, then AnyEvent will fall back to its own
		777	pure-perl implementation, which is available everywhere as it comes
		778	with AnyEvent itself.
		779
		780	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		781	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		782
		783	Backends that are transparently being picked up when they are used.
		784	These will be used when they are currently loaded when the first
		785	watcher is created, in which case it is assumed that the application
		786	is using them. This means that AnyEvent will automatically pick the
		787	right backend when the main program loads an event module before
		788	anything starts to create watchers. Nothing special needs to be done
		789	by the main program.
		790
		791	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		792	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		793	AnyEvent::Impl::Tk based on Tk, very broken.
		794	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		795	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		796	AnyEvent::Impl::Irssi used when running within irssi.
		797
		798	Backends with special needs.
		799	Qt requires the Qt::Application to be instantiated first, but will
		800	otherwise be picked up automatically. As long as the main program
		801	instantiates the application before any AnyEvent watchers are
		802	created, everything should just work.
		803
		804	AnyEvent::Impl::Qt based on Qt.
		805
		806	Support for IO::Async can only be partial, as it is too broken and
		807	architecturally limited to even support the AnyEvent API. It also is
		808	the only event loop that needs the loop to be set explicitly, so it
		809	can only be used by a main program knowing about AnyEvent. See
		810	AnyEvent::Impl::Async for the gory details.
		811
		812	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		813
		814	Event loops that are indirectly supported via other backends.
		815	Some event loops can be supported via other modules:
		816
		817	There is no direct support for WxWidgets (Wx) or Prima.
		818
		819	WxWidgets has no support for watching file handles. However, you can
		820	use WxWidgets through the POE adaptor, as POE has a Wx backend that
		821	simply polls 20 times per second, which was considered to be too
		822	horrible to even consider for AnyEvent.
		823
		824	Prima is not supported as nobody seems to be using it, but it has a
		825	POE backend, so it can be supported through POE.
		826
		827	AnyEvent knows about both Prima and Wx, however, and will try to
		828	load POE when detecting them, in the hope that POE will pick them
		829	up, in which case everything will be automatic.
580		830
581	GLOBAL VARIABLES AND FUNCTIONS	831	GLOBAL VARIABLES AND FUNCTIONS
		832	These are not normally required to use AnyEvent, but can be useful to
		833	write AnyEvent extension modules.
		834
582	$AnyEvent::MODEL	835	$AnyEvent::MODEL
583	Contains "undef" until the first watcher is being created. Then it	836	Contains "undef" until the first watcher is being created, before
		837	the backend has been autodetected.
		838
584	contains the event model that is being used, which is the name of	839	Afterwards it contains the event model that is being used, which is
585	the Perl class implementing the model. This class is usually one of	840	the name of the Perl class implementing the model. This class is
586	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	841	usually one of the "AnyEvent::Impl:xxx" modules, but can be any
587	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	842	other class in the case AnyEvent has been extended at runtime (e.g.
588		843	in rxvt-unicode it will be "urxvt::anyevent").
589	The known classes so far are:
590
591	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
592	AnyEvent::Impl::Event based on Event, second best choice.
593	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
594	AnyEvent::Impl::Glib based on Glib, third-best choice.
595	AnyEvent::Impl::Tk based on Tk, very bad choice.
596	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
597	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
598	AnyEvent::Impl::POE based on POE, not generic enough for full support.
599
600	There is no support for WxWidgets, as WxWidgets has no support for
601	watching file handles. However, you can use WxWidgets through the
602	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
603	second, which was considered to be too horrible to even consider for
604	AnyEvent. Likewise, other POE backends can be used by AnyEvent by
605	using it's adaptor.
606
607	AnyEvent knows about Prima and Wx and will try to use POE when
608	autodetecting them.
609		844
610	AnyEvent::detect	845	AnyEvent::detect
611	Returns $AnyEvent::MODEL, forcing autodetection of the event model	846	Returns $AnyEvent::MODEL, forcing autodetection of the event model
612	if necessary. You should only call this function right before you	847	if necessary. You should only call this function right before you
613	would have created an AnyEvent watcher anyway, that is, as late as	848	would have created an AnyEvent watcher anyway, that is, as late as
614	possible at runtime.	849	possible at runtime, and not e.g. while initialising of your module.
		850
		851	If you need to do some initialisation before AnyEvent watchers are
		852	created, use "post_detect".
615		853
616	$guard = AnyEvent::post_detect { BLOCK }	854	$guard = AnyEvent::post_detect { BLOCK }
617	Arranges for the code block to be executed as soon as the event	855	Arranges for the code block to be executed as soon as the event
618	model is autodetected (or immediately if this has already happened).	856	model is autodetected (or immediately if this has already happened).
619		857
		858	The block will be executed after the actual backend has been
		859	detected ($AnyEvent::MODEL is set), but before any watchers have
		860	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
		861	other initialisations - see the sources of AnyEvent::Strict or
		862	AnyEvent::AIO to see how this is used.
		863
		864	The most common usage is to create some global watchers, without
		865	forcing event module detection too early, for example, AnyEvent::AIO
		866	creates and installs the global IO::AIO watcher in a "post_detect"
		867	block to avoid autodetecting the event module at load time.
		868
620	If called in scalar or list context, then it creates and returns an	869	If called in scalar or list context, then it creates and returns an
621	object that automatically removes the callback again when it is	870	object that automatically removes the callback again when it is
		871	destroyed (or "undef" when the hook was immediately executed). See
622	destroyed. See Coro::BDB for a case where this is useful.	872	AnyEvent::AIO for a case where this is useful.
		873
		874	Example: Create a watcher for the IO::AIO module and store it in
		875	$WATCHER. Only do so after the event loop is initialised, though.
		876
		877	our WATCHER;
		878
		879	my $guard = AnyEvent::post_detect {
		880	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		881	};
		882
		883	# the \|\|= is important in case post_detect immediately runs the block,
		884	# as to not clobber the newly-created watcher. assigning both watcher and
		885	# post_detect guard to the same variable has the advantage of users being
		886	# able to just C<undef $WATCHER> if the watcher causes them grief.
		887
		888	$WATCHER \|\|= $guard;
623		889
624	@AnyEvent::post_detect	890	@AnyEvent::post_detect
625	If there are any code references in this array (you can "push" to it	891	If there are any code references in this array (you can "push" to it
626	before or after loading AnyEvent), then they will called directly	892	before or after loading AnyEvent), then they will called directly
627	after the event loop has been chosen.	893	after the event loop has been chosen.
628		894
629	You should check $AnyEvent::MODEL before adding to this array,	895	You should check $AnyEvent::MODEL before adding to this array,
630	though: if it contains a true value then the event loop has already	896	though: if it is defined then the event loop has already been
631	been detected, and the array will be ignored.	897	detected, and the array will be ignored.
632		898
633	Best use "AnyEvent::post_detect { BLOCK }" instead.	899	Best use "AnyEvent::post_detect { BLOCK }" when your application
		900	allows it,as it takes care of these details.
		901
		902	This variable is mainly useful for modules that can do something
		903	useful when AnyEvent is used and thus want to know when it is
		904	initialised, but do not need to even load it by default. This array
		905	provides the means to hook into AnyEvent passively, without loading
		906	it.
634		907
635	WHAT TO DO IN A MODULE	908	WHAT TO DO IN A MODULE
636	As a module author, you should "use AnyEvent" and call AnyEvent methods	909	As a module author, you should "use AnyEvent" and call AnyEvent methods
637	freely, but you should not load a specific event module or rely on it.	910	freely, but you should not load a specific event module or rely on it.
638		911
…		…
689	variable somewhere, waiting for it, and sending it when the program	962	variable somewhere, waiting for it, and sending it when the program
690	should exit cleanly.	963	should exit cleanly.
691		964
692	OTHER MODULES	965	OTHER MODULES
693	The following is a non-exhaustive list of additional modules that use	966	The following is a non-exhaustive list of additional modules that use
694	AnyEvent and can therefore be mixed easily with other AnyEvent modules	967	AnyEvent as a client and can therefore be mixed easily with other
695	in the same program. Some of the modules come with AnyEvent, some are	968	AnyEvent modules and other event loops in the same program. Some of the
696	available via CPAN.	969	modules come with AnyEvent, most are available via CPAN.
697		970
698	AnyEvent::Util	971	AnyEvent::Util
699	Contains various utility functions that replace often-used but	972	Contains various utility functions that replace often-used but
700	blocking functions such as "inet_aton" by event-/callback-based	973	blocking functions such as "inet_aton" by event-/callback-based
701	versions.	974	versions.
…		…
707	more.	980	more.
708		981
709	AnyEvent::Handle	982	AnyEvent::Handle
710	Provide read and write buffers, manages watchers for reads and	983	Provide read and write buffers, manages watchers for reads and
711	writes, supports raw and formatted I/O, I/O queued and fully	984	writes, supports raw and formatted I/O, I/O queued and fully
712	transparent and non-blocking SSL/TLS.	985	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
713		986
714	AnyEvent::DNS	987	AnyEvent::DNS
715	Provides rich asynchronous DNS resolver capabilities.	988	Provides rich asynchronous DNS resolver capabilities.
716		989
717	AnyEvent::HTTP	990	AnyEvent::HTTP
…		…
738		1011
739	AnyEvent::GPSD	1012	AnyEvent::GPSD
740	A non-blocking interface to gpsd, a daemon delivering GPS	1013	A non-blocking interface to gpsd, a daemon delivering GPS
741	information.	1014	information.
742		1015
		1016	AnyEvent::IRC
		1017	AnyEvent based IRC client module family (replacing the older
		1018	Net::IRC3).
		1019
		1020	AnyEvent::XMPP
		1021	AnyEvent based XMPP (Jabber protocol) module family (replacing the
		1022	older Net::XMPP2>.
		1023
743	AnyEvent::IGS	1024	AnyEvent::IGS
744	A non-blocking interface to the Internet Go Server protocol (used by	1025	A non-blocking interface to the Internet Go Server protocol (used by
745	App::IGS).	1026	App::IGS).
746		1027
747	Net::IRC3
748	AnyEvent based IRC client module family.
749
750	Net::XMPP2
751	AnyEvent based XMPP (Jabber protocol) module family.
752
753	Net::FCP	1028	Net::FCP
754	AnyEvent-based implementation of the Freenet Client Protocol,	1029	AnyEvent-based implementation of the Freenet Client Protocol,
755	birthplace of AnyEvent.	1030	birthplace of AnyEvent.
756		1031
757	Event::ExecFlow	1032	Event::ExecFlow
758	High level API for event-based execution flow control.	1033	High level API for event-based execution flow control.
759		1034
760	Coro	1035	Coro
761	Has special support for AnyEvent via Coro::AnyEvent.	1036	Has special support for AnyEvent via Coro::AnyEvent.
762		1037
763	IO::Lambda	1038	SIMPLIFIED AE API
764	The lambda approach to I/O - don't ask, look there. Can use	1039	Starting with version 5.0, AnyEvent officially supports a second, much
765	AnyEvent.	1040	simpler, API that is designed to reduce the calling, typing and memory
		1041	overhead.
766		1042
767	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1043	See the AE manpage for details.
768	This is an advanced topic that you do not normally need to use AnyEvent
769	in a module. This section is only of use to event loop authors who want
770	to provide AnyEvent compatibility.
771		1044
772	If you need to support another event library which isn't directly	1045	ERROR AND EXCEPTION HANDLING
773	supported by AnyEvent, you can supply your own interface to it by	1046	In general, AnyEvent does not do any error handling - it relies on the
774	pushing, before the first watcher gets created, the package name of the	1047	caller to do that if required. The AnyEvent::Strict module (see also the
775	event module and the package name of the interface to use onto	1048	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
776	@AnyEvent::REGISTRY. You can do that before and even without loading	1049	checking of all AnyEvent methods, however, which is highly useful during
777	AnyEvent, so it is reasonably cheap.	1050	development.
778		1051
779	Example:	1052	As for exception handling (i.e. runtime errors and exceptions thrown
		1053	while executing a callback), this is not only highly event-loop
		1054	specific, but also not in any way wrapped by this module, as this is the
		1055	job of the main program.
780		1056
781	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	1057	The pure perl event loop simply re-throws the exception (usually within
782		1058	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
783	This tells AnyEvent to (literally) use the "urxvt::anyevent::"	1059	Glib uses "install_exception_handler" and so on.
784	package/class when it finds the "urxvt" package/module is already
785	loaded.
786
787	When AnyEvent is loaded and asked to find a suitable event model, it
788	will first check for the presence of urxvt by trying to "use" the
789	"urxvt::anyevent" module.
790
791	The class should provide implementations for all watcher types. See
792	AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
793	so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
794	the sources.
795
796	If you don't provide "signal" and "child" watchers than AnyEvent will
797	provide suitable (hopefully) replacements.
798
799	The above example isn't fictitious, the rxvt-unicode (a.k.a. urxvt)
800	terminal emulator uses the above line as-is. An interface isn't included
801	in AnyEvent because it doesn't make sense outside the embedded
802	interpreter inside rxvt-unicode, and it is updated and maintained as
803	part of the rxvt-unicode distribution.
804
805	rxvt-unicode also cheats a bit by not providing blocking access to
806	condition variables: code blocking while waiting for a condition will
807	"die". This still works with most modules/usages, and blocking calls
808	must not be done in an interactive application, so it makes sense.
809		1060
810	ENVIRONMENT VARIABLES	1061	ENVIRONMENT VARIABLES
811	The following environment variables are used by this module:	1062	The following environment variables are used by this module or its
		1063	submodules.
		1064
		1065	Note that AnyEvent will remove all environment variables starting with
		1066	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		1067	enabled.
812		1068
813	"PERL_ANYEVENT_VERBOSE"	1069	"PERL_ANYEVENT_VERBOSE"
814	By default, AnyEvent will be completely silent except in fatal	1070	By default, AnyEvent will be completely silent except in fatal
815	conditions. You can set this environment variable to make AnyEvent	1071	conditions. You can set this environment variable to make AnyEvent
816	more talkative.	1072	more talkative.
…		…
819	conditions, such as not being able to load the event model specified	1075	conditions, such as not being able to load the event model specified
820	by "PERL_ANYEVENT_MODEL".	1076	by "PERL_ANYEVENT_MODEL".
821		1077
822	When set to 2 or higher, cause AnyEvent to report to STDERR which	1078	When set to 2 or higher, cause AnyEvent to report to STDERR which
823	event model it chooses.	1079	event model it chooses.
		1080
		1081	When set to 8 or higher, then AnyEvent will report extra information
		1082	on which optional modules it loads and how it implements certain
		1083	features.
824		1084
825	"PERL_ANYEVENT_STRICT"	1085	"PERL_ANYEVENT_STRICT"
826	AnyEvent does not do much argument checking by default, as thorough	1086	AnyEvent does not do much argument checking by default, as thorough
827	argument checking is very costly. Setting this variable to a true	1087	argument checking is very costly. Setting this variable to a true
828	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1088	value will cause AnyEvent to load "AnyEvent::Strict" and then to
829	thoroughly check the arguments passed to most method calls. If it	1089	thoroughly check the arguments passed to most method calls. If it
830	finds any problems it will croak.	1090	finds any problems, it will croak.
831		1091
832	In other words, enables "strict" mode.	1092	In other words, enables "strict" mode.
833		1093
834	Unlike "use strict" it is definitely recommended ot keep it off in	1094	Unlike "use strict" (or it's modern cousin, "use common::sense", it
835	production.	1095	is definitely recommended to keep it off in production. Keeping
		1096	"PERL_ANYEVENT_STRICT=1" in your environment while developing
		1097	programs can be very useful, however.
836		1098
837	"PERL_ANYEVENT_MODEL"	1099	"PERL_ANYEVENT_MODEL"
838	This can be used to specify the event model to be used by AnyEvent,	1100	This can be used to specify the event model to be used by AnyEvent,
839	before auto detection and -probing kicks in. It must be a string	1101	before auto detection and -probing kicks in. It must be a string
840	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1102	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
…		…
859	mentioned will be used, and preference will be given to protocols	1121	mentioned will be used, and preference will be given to protocols
860	mentioned earlier in the list.	1122	mentioned earlier in the list.
861		1123
862	This variable can effectively be used for denial-of-service attacks	1124	This variable can effectively be used for denial-of-service attacks
863	against local programs (e.g. when setuid), although the impact is	1125	against local programs (e.g. when setuid), although the impact is
864	likely small, as the program has to handle connection errors	1126	likely small, as the program has to handle conenction and other
865	already-	1127	failures anyways.
866		1128
867	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over	1129	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over
868	IPv6, but support both and try to use both.	1130	IPv6, but support both and try to use both.
869	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to	1131	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
870	resolve or contact IPv6 addresses.	1132	resolve or contact IPv6 addresses.
…		…
881	EDNS0 in its DNS requests.	1143	EDNS0 in its DNS requests.
882		1144
883	"PERL_ANYEVENT_MAX_FORKS"	1145	"PERL_ANYEVENT_MAX_FORKS"
884	The maximum number of child processes that	1146	The maximum number of child processes that
885	"AnyEvent::Util::fork_call" will create in parallel.	1147	"AnyEvent::Util::fork_call" will create in parallel.
		1148
		1149	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
		1150	The default value for the "max_outstanding" parameter for the
		1151	default DNS resolver - this is the maximum number of parallel DNS
		1152	requests that are sent to the DNS server.
		1153
		1154	"PERL_ANYEVENT_RESOLV_CONF"
		1155	The file to use instead of /etc/resolv.conf (or OS-specific
		1156	configuration) in the default resolver. When set to the empty
		1157	string, no default config will be used.
		1158
		1159	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
		1160	When neither "ca_file" nor "ca_path" was specified during
		1161	AnyEvent::TLS context creation, and either of these environment
		1162	variables exist, they will be used to specify CA certificate
		1163	locations instead of a system-dependent default.
		1164
		1165	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
		1166	When these are set to 1, then the respective modules are not loaded.
		1167	Mostly good for testing AnyEvent itself.
		1168
		1169	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		1170	This is an advanced topic that you do not normally need to use AnyEvent
		1171	in a module. This section is only of use to event loop authors who want
		1172	to provide AnyEvent compatibility.
		1173
		1174	If you need to support another event library which isn't directly
		1175	supported by AnyEvent, you can supply your own interface to it by
		1176	pushing, before the first watcher gets created, the package name of the
		1177	event module and the package name of the interface to use onto
		1178	@AnyEvent::REGISTRY. You can do that before and even without loading
		1179	AnyEvent, so it is reasonably cheap.
		1180
		1181	Example:
		1182
		1183	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
		1184
		1185	This tells AnyEvent to (literally) use the "urxvt::anyevent::"
		1186	package/class when it finds the "urxvt" package/module is already
		1187	loaded.
		1188
		1189	When AnyEvent is loaded and asked to find a suitable event model, it
		1190	will first check for the presence of urxvt by trying to "use" the
		1191	"urxvt::anyevent" module.
		1192
		1193	The class should provide implementations for all watcher types. See
		1194	AnyEvent::Impl::EV (source code), AnyEvent::Impl::Glib (Source code) and
		1195	so on for actual examples. Use "perldoc -m AnyEvent::Impl::Glib" to see
		1196	the sources.
		1197
		1198	If you don't provide "signal" and "child" watchers than AnyEvent will
		1199	provide suitable (hopefully) replacements.
		1200
		1201	The above example isn't fictitious, the rxvt-unicode (a.k.a. urxvt)
		1202	terminal emulator uses the above line as-is. An interface isn't included
		1203	in AnyEvent because it doesn't make sense outside the embedded
		1204	interpreter inside rxvt-unicode, and it is updated and maintained as
		1205	part of the rxvt-unicode distribution.
		1206
		1207	rxvt-unicode also cheats a bit by not providing blocking access to
		1208	condition variables: code blocking while waiting for a condition will
		1209	"die". This still works with most modules/usages, and blocking calls
		1210	must not be done in an interactive application, so it makes sense.
886		1211
887	EXAMPLE PROGRAM	1212	EXAMPLE PROGRAM
888	The following program uses an I/O watcher to read data from STDIN, a	1213	The following program uses an I/O watcher to read data from STDIN, a
889	timer to display a message once per second, and a condition variable to	1214	timer to display a message once per second, and a condition variable to
890	quit the program when the user enters quit:	1215	quit the program when the user enters quit:
…		…
1048	through AnyEvent. The benchmark creates a lot of timers (with a zero	1373	through AnyEvent. The benchmark creates a lot of timers (with a zero
1049	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1374	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1050	which it is), lets them fire exactly once and destroys them again.	1375	which it is), lets them fire exactly once and destroys them again.
1051		1376
1052	Source code for this benchmark is found as eg/bench in the AnyEvent	1377	Source code for this benchmark is found as eg/bench in the AnyEvent
1053	distribution.	1378	distribution. It uses the AE interface, which makes a real difference
		1379	for the EV and Perl backends only.
1054		1380
1055	Explanation of the columns	1381	Explanation of the columns
1056	watcher is the number of event watchers created/destroyed. Since	1382	watcher is the number of event watchers created/destroyed. Since
1057	different event models feature vastly different performances, each event	1383	different event models feature vastly different performances, each event
1058	loop was given a number of watchers so that overall runtime is	1384	loop was given a number of watchers so that overall runtime is
…		…
1077	destroy is the time, in microseconds, that it takes to destroy a	1403	destroy is the time, in microseconds, that it takes to destroy a
1078	single watcher.	1404	single watcher.
1079		1405
1080	Results	1406	Results
1081	name watchers bytes create invoke destroy comment	1407	name watchers bytes create invoke destroy comment
1082	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1408	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1083	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1409	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1084	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1410	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1085	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1411	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1086	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1412	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1087	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1413	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		1414	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		1415	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1088	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1416	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1089	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1417	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1090	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1418	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1091	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1419	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1092		1420
1093	Discussion	1421	Discussion
1094	The benchmark does not measure scalability of the event loop very	1422	The benchmark does not measure scalability of the event loop very
1095	well. For example, a select-based event loop (such as the pure perl one)	1423	well. For example, a select-based event loop (such as the pure perl one)
1096	can never compete with an event loop that uses epoll when the number of	1424	can never compete with an event loop that uses epoll when the number of
…		…
1107	benchmark machine, handling an event takes roughly 1600 CPU cycles with	1435	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1108	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000	1436	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1109	CPU cycles with POE.	1437	CPU cycles with POE.
1110		1438
1111	"EV" is the sole leader regarding speed and memory use, which are both	1439	"EV" is the sole leader regarding speed and memory use, which are both
1112	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1440	maximal/minimal, respectively. When using the AE API there is zero
		1441	overhead (when going through the AnyEvent API create is about 5-6 times
		1442	slower, with other times being equal, so still uses far less memory than
1113	far less memory than any other event loop and is still faster than Event	1443	any other event loop and is still faster than Event natively).
1114	natively.
1115		1444
1116	The pure perl implementation is hit in a few sweet spots (both the	1445	The pure perl implementation is hit in a few sweet spots (both the
1117	constant timeout and the use of a single fd hit optimisations in the	1446	constant timeout and the use of a single fd hit optimisations in the
1118	perl interpreter and the backend itself). Nevertheless this shows that	1447	perl interpreter and the backend itself). Nevertheless this shows that
1119	it adds very little overhead in itself. Like any select-based backend	1448	it adds very little overhead in itself. Like any select-based backend
…		…
1121	few of them active), of course, but this was not subject of this	1450	few of them active), of course, but this was not subject of this
1122	benchmark.	1451	benchmark.
1123		1452
1124	The "Event" module has a relatively high setup and callback invocation	1453	The "Event" module has a relatively high setup and callback invocation
1125	cost, but overall scores in on the third place.	1454	cost, but overall scores in on the third place.
		1455
		1456	"IO::Async" performs admirably well, about on par with "Event", even
		1457	when using its pure perl backend.
1126		1458
1127	"Glib"'s memory usage is quite a bit higher, but it features a faster	1459	"Glib"'s memory usage is quite a bit higher, but it features a faster
1128	callback invocation and overall ends up in the same class as "Event".	1460	callback invocation and overall ends up in the same class as "Event".
1129	However, Glib scales extremely badly, doubling the number of watchers	1461	However, Glib scales extremely badly, doubling the number of watchers
1130	increases the processing time by more than a factor of four, making it	1462	increases the processing time by more than a factor of four, making it
…		…
1186	In this benchmark, we use 10000 socket pairs (20000 sockets), of which	1518	In this benchmark, we use 10000 socket pairs (20000 sockets), of which
1187	100 (1%) are active. This mirrors the activity of large servers with	1519	100 (1%) are active. This mirrors the activity of large servers with
1188	many connections, most of which are idle at any one point in time.	1520	many connections, most of which are idle at any one point in time.
1189		1521
1190	Source code for this benchmark is found as eg/bench2 in the AnyEvent	1522	Source code for this benchmark is found as eg/bench2 in the AnyEvent
1191	distribution.	1523	distribution. It uses the AE interface, which makes a real difference
		1524	for the EV and Perl backends only.
1192		1525
1193	Explanation of the columns	1526	Explanation of the columns
1194	sockets is the number of sockets, and twice the number of "servers"	1527	sockets is the number of sockets, and twice the number of "servers"
1195	(as each server has a read and write socket end).	1528	(as each server has a read and write socket end).
1196		1529
…		…
1201	single "request", that is, reading the token from the pipe and	1534	single "request", that is, reading the token from the pipe and
1202	forwarding it to another server. This includes deleting the old timeout	1535	forwarding it to another server. This includes deleting the old timeout
1203	and creating a new one that moves the timeout into the future.	1536	and creating a new one that moves the timeout into the future.
1204		1537
1205	Results	1538	Results
1206	name sockets create request	1539	name sockets create request
1207	EV 20000 69.01 11.16	1540	EV 20000 62.66 7.99
1208	Perl 20000 73.32 35.87	1541	Perl 20000 68.32 32.64
1209	Event 20000 212.62 257.32	1542	IOAsync 20000 174.06 101.15 epoll
1210	Glib 20000 651.16 1896.30	1543	IOAsync 20000 174.67 610.84 poll
		1544	Event 20000 202.69 242.91
		1545	Glib 20000 557.01 1689.52
1211	POE 20000 349.67 12317.24 uses POE::Loop::Event	1546	POE 20000 341.54 12086.32 uses POE::Loop::Event
1212		1547
1213	Discussion	1548	Discussion
1214	This benchmark does measure scalability and overall performance of the	1549	This benchmark does measure scalability and overall performance of the
1215	particular event loop.	1550	particular event loop.
1216		1551
1217	EV is again fastest. Since it is using epoll on my system, the setup	1552	EV is again fastest. Since it is using epoll on my system, the setup
1218	time is relatively high, though.	1553	time is relatively high, though.
1219		1554
1220	Perl surprisingly comes second. It is much faster than the C-based event	1555	Perl surprisingly comes second. It is much faster than the C-based event
1221	loops Event and Glib.	1556	loops Event and Glib.
		1557
		1558	IO::Async performs very well when using its epoll backend, and still
		1559	quite good compared to Glib when using its pure perl backend.
1222		1560
1223	Event suffers from high setup time as well (look at its code and you	1561	Event suffers from high setup time as well (look at its code and you
1224	will understand why). Callback invocation also has a high overhead	1562	will understand why). Callback invocation also has a high overhead
1225	compared to the "$_->() for .."-style loop that the Perl event loop	1563	compared to the "$_->() for .."-style loop that the Perl event loop
1226	uses. Event uses select or poll in basically all documented	1564	uses. Event uses select or poll in basically all documented
…		…
1277		1615
1278	Summary	1616	Summary
1279	* C-based event loops perform very well with small number of watchers,	1617	* C-based event loops perform very well with small number of watchers,
1280	as the management overhead dominates.	1618	as the management overhead dominates.
1281		1619
		1620	THE IO::Lambda BENCHMARK
		1621	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1622	could be misinterpreted to make AnyEvent look bad. In fact, the
		1623	benchmark simply compares IO::Lambda with POE, and IO::Lambda looks
		1624	better (which shouldn't come as a surprise to anybody). As such, the
		1625	benchmark is fine, and mostly shows that the AnyEvent backend from
		1626	IO::Lambda isn't very optimal. But how would AnyEvent compare when used
		1627	without the extra baggage? To explore this, I wrote the equivalent
		1628	benchmark for AnyEvent.
		1629
		1630	The benchmark itself creates an echo-server, and then, for 500 times,
		1631	connects to the echo server, sends a line, waits for the reply, and then
		1632	creates the next connection. This is a rather bad benchmark, as it
		1633	doesn't test the efficiency of the framework or much non-blocking I/O,
		1634	but it is a benchmark nevertheless.
		1635
		1636	name runtime
		1637	Lambda/select 0.330 sec
		1638	+ optimized 0.122 sec
		1639	Lambda/AnyEvent 0.327 sec
		1640	+ optimized 0.138 sec
		1641	Raw sockets/select 0.077 sec
		1642	POE/select, components 0.662 sec
		1643	POE/select, raw sockets 0.226 sec
		1644	POE/select, optimized 0.404 sec
		1645
		1646	AnyEvent/select/nb 0.085 sec
		1647	AnyEvent/EV/nb 0.068 sec
		1648	+state machine 0.134 sec
		1649
		1650	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1651	benchmarks actually make blocking connects and use 100% blocking I/O,
		1652	defeating the purpose of an event-based solution. All of the newly
		1653	written AnyEvent benchmarks use 100% non-blocking connects (using
		1654	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1655	resolver), so AnyEvent is at a disadvantage here, as non-blocking
		1656	connects generally require a lot more bookkeeping and event handling
		1657	than blocking connects (which involve a single syscall only).
		1658
		1659	The last AnyEvent benchmark additionally uses AnyEvent::Handle, which
		1660	offers similar expressive power as POE and IO::Lambda, using
		1661	conventional Perl syntax. This means that both the echo server and the
		1662	client are 100% non-blocking, further placing it at a disadvantage.
		1663
		1664	As you can see, the AnyEvent + EV combination even beats the
		1665	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1666	backend easily beats IO::Lambda and POE.
		1667
		1668	And even the 100% non-blocking version written using the high-level (and
		1669	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a
		1670	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1671	in a non-blocking way.
		1672
		1673	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
		1674	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
		1675	part of the IO::lambda distribution and were used without any changes.
		1676
		1677	SIGNALS
		1678	AnyEvent currently installs handlers for these signals:
		1679
		1680	SIGCHLD
		1681	A handler for "SIGCHLD" is installed by AnyEvent's child watcher
		1682	emulation for event loops that do not support them natively. Also,
		1683	some event loops install a similar handler.
		1684
		1685	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE,
		1686	then AnyEvent will reset it to default, to avoid losing child exit
		1687	statuses.
		1688
		1689	SIGPIPE
		1690	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
		1691	"undef" when AnyEvent gets loaded.
		1692
		1693	The rationale for this is that AnyEvent users usually do not really
		1694	depend on SIGPIPE delivery (which is purely an optimisation for
		1695	shell use, or badly-written programs), but "SIGPIPE" can cause
		1696	spurious and rare program exits as a lot of people do not expect
		1697	"SIGPIPE" when writing to some random socket.
		1698
		1699	The rationale for installing a no-op handler as opposed to ignoring
		1700	it is that this way, the handler will be restored to defaults on
		1701	exec.
		1702
		1703	Feel free to install your own handler, or reset it to defaults.
		1704
		1705	RECOMMENDED/OPTIONAL MODULES
		1706	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		1707	it's built-in modules) are required to use it.
		1708
		1709	That does not mean that AnyEvent won't take advantage of some additional
		1710	modules if they are installed.
		1711
		1712	This section epxlains which additional modules will be used, and how
		1713	they affect AnyEvent's operetion.
		1714
		1715	Async::Interrupt
		1716	This slightly arcane module is used to implement fast signal
		1717	handling: To my knowledge, there is no way to do completely
		1718	race-free and quick signal handling in pure perl. To ensure that
		1719	signals still get delivered, AnyEvent will start an interval timer
		1720	to wake up perl (and catch the signals) with some delay (default is
		1721	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
		1722
		1723	If this module is available, then it will be used to implement
		1724	signal catching, which means that signals will not be delayed, and
		1725	the event loop will not be interrupted regularly, which is more
		1726	efficient (And good for battery life on laptops).
		1727
		1728	This affects not just the pure-perl event loop, but also other event
		1729	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
		1730
		1731	Some event loops (POE, Event, Event::Lib) offer signal watchers
		1732	natively, and either employ their own workarounds (POE) or use
		1733	AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
		1734	Installing Async::Interrupt does nothing for those backends.
		1735
		1736	EV This module isn't really "optional", as it is simply one of the
		1737	backend event loops that AnyEvent can use. However, it is simply the
		1738	best event loop available in terms of features, speed and stability:
		1739	It supports the AnyEvent API optimally, implements all the watcher
		1740	types in XS, does automatic timer adjustments even when no monotonic
		1741	clock is available, can take avdantage of advanced kernel interfaces
		1742	such as "epoll" and "kqueue", and is the fastest backend by far.
		1743	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
		1744	Glib::EV).
		1745
		1746	Guard
		1747	The guard module, when used, will be used to implement
		1748	"AnyEvent::Util::guard". This speeds up guards considerably (and
		1749	uses a lot less memory), but otherwise doesn't affect guard
		1750	operation much. It is purely used for performance.
		1751
		1752	JSON and JSON::XS
		1753	This module is required when you want to read or write JSON data via
		1754	AnyEvent::Handle. It is also written in pure-perl, but can take
		1755	advantage of the ultra-high-speed JSON::XS module when it is
		1756	installed.
		1757
		1758	In fact, AnyEvent::Handle will use JSON::XS by default if it is
		1759	installed.
		1760
		1761	Net::SSLeay
		1762	Implementing TLS/SSL in Perl is certainly interesting, but not very
		1763	worthwhile: If this module is installed, then AnyEvent::Handle (with
		1764	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
		1765
		1766	Time::HiRes
		1767	This module is part of perl since release 5.008. It will be used
		1768	when the chosen event library does not come with a timing source on
		1769	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will
		1770	additionally use it to try to use a monotonic clock for timing
		1771	stability.
		1772
1282	FORK	1773	FORK
1283	Most event libraries are not fork-safe. The ones who are usually are	1774	Most event libraries are not fork-safe. The ones who are usually are
1284	because they rely on inefficient but fork-safe "select" or "poll" calls.	1775	because they rely on inefficient but fork-safe "select" or "poll" calls.
1285	Only EV is fully fork-aware.	1776	Only EV is fully fork-aware.
1286		1777
1287	If you have to fork, you must either do so before creating your first	1778	If you have to fork, you must either do so before creating your first
1288	watcher OR you must not use AnyEvent at all in the child.	1779	watcher OR you must not use AnyEvent at all in the child OR you must do
		1780	something completely out of the scope of AnyEvent.
1289		1781
1290	SECURITY CONSIDERATIONS	1782	SECURITY CONSIDERATIONS
1291	AnyEvent can be forced to load any event model via	1783	AnyEvent can be forced to load any event model via
1292	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1784	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1293	to execute arbitrary code or directly gain access, it can easily be used	1785	to execute arbitrary code or directly gain access, it can easily be used
…		…
1297		1789
1298	You can make AnyEvent completely ignore this variable by deleting it	1790	You can make AnyEvent completely ignore this variable by deleting it
1299	before the first watcher gets created, e.g. with a "BEGIN" block:	1791	before the first watcher gets created, e.g. with a "BEGIN" block:
1300		1792
1301	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1793	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1302		1794
1303	use AnyEvent;	1795	use AnyEvent;
1304		1796
1305	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1797	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1306	be used to probe what backend is used and gain other information (which	1798	be used to probe what backend is used and gain other information (which
1307	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),	1799	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1308	and $ENV{PERL_ANYEGENT_STRICT}.	1800	and $ENV{PERL_ANYEVENT_STRICT}.
		1801
		1802	Note that AnyEvent will remove all environment variables starting with
		1803	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		1804	enabled.
1309		1805
1310	BUGS	1806	BUGS
1311	Perl 5.8 has numerous memleaks that sometimes hit this module and are	1807	Perl 5.8 has numerous memleaks that sometimes hit this module and are
1312	hard to work around. If you suffer from memleaks, first upgrade to Perl	1808	hard to work around. If you suffer from memleaks, first upgrade to Perl
1313	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1809	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1314	annoying mamleaks, such as leaking on "map" and "grep" but it is usually	1810	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1315	not as pronounced).	1811	not as pronounced).
1316		1812
1317	SEE ALSO	1813	SEE ALSO
1318	Utility functions: AnyEvent::Util.	1814	Utility functions: AnyEvent::Util.
1319		1815
1320	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1816	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1321	Event::Lib, Qt, POE.	1817	Event::Lib, Qt, POE.
1322		1818
1323	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1819	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1324	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1820	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1325	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1821	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		1822	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1326		1823
1327	Non-blocking file handles, sockets, TCP clients and servers:	1824	Non-blocking file handles, sockets, TCP clients and servers:
1328	AnyEvent::Handle, AnyEvent::Socket.	1825	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1329		1826
1330	Asynchronous DNS: AnyEvent::DNS.	1827	Asynchronous DNS: AnyEvent::DNS.
1331		1828
1332	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1829	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1333		1830
1334	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.	1831	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
		1832	AnyEvent::HTTP.
1335		1833
1336	AUTHOR	1834	AUTHOR
1337	Marc Lehmann <schmorp@schmorp.de>	1835	Marc Lehmann <schmorp@schmorp.de>
1338	http://home.schmorp.de/	1836	http://home.schmorp.de/
1339		1837

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Comparing AnyEvent/README (file contents): Revision 1.28 by root, Sat Jul 12 20:45:27 2008 UTC vs. Revision 1.51 by root, Sun Aug 9 16:05:11 2009 UTC

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Comparing AnyEvent/README (file contents):
Revision 1.28 by root, Sat Jul 12 20:45:27 2008 UTC vs.
Revision 1.51 by root, Sun Aug 9 16:05:11 2009 UTC