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Revision 1.41 by root, Fri Jun 26 06:33:17 2009 UTC vs.
Revision 1.56 by root, Thu Nov 19 01:55:57 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 and POE are various supported	4	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async,
5	event 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	# file descriptor readable
37		37
38	INTRODUCTION/TUTORIAL	38	INTRODUCTION/TUTORIAL
39	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
40	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
41	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.
42		49
43	WHY YOU SHOULD USE THIS MODULE (OR NOT)	50	WHY YOU SHOULD USE THIS MODULE (OR NOT)
44	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
45	nowadays. So what is different about AnyEvent?	52	nowadays. So what is different about AnyEvent?
46		53
…		…
166	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,
167	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
168	declared.	175	declared.
169		176
170	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
171	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
172	the following mandatory key-value pairs as arguments:	185	the following mandatory key-value pairs as arguments:
173		186
174	"fh" is the Perl file handle (not file descriptor) to watch for	187	"fh" is the Perl file handle (or a naked file descriptor) to watch for
175	events (AnyEvent might or might not keep a reference to this file	188	events (AnyEvent might or might not keep a reference to this file
176	handle). Note that only file handles pointing to things for which	189	handle). Note that only file handles pointing to things for which
177	non-blocking operation makes sense are allowed. This includes sockets,	190	non-blocking operation makes sense are allowed. This includes sockets,
178	most character devices, pipes, fifos and so on, but not for example	191	most character devices, pipes, fifos and so on, but not for example
179	files or block devices.	192	files or block devices.
…		…
203	warn "read: $input\n";	216	warn "read: $input\n";
204	undef $w;	217	undef $w;
205	});	218	});
206		219
207	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
208	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
209	with the following mandatory arguments:	230	with the following mandatory arguments:
210		231
211	"after" specifies after how many seconds (fractional values are	232	"after" specifies after how many seconds (fractional values are
212	supported) the callback should be invoked. "cb" is the callback to	233	supported) the callback should be invoked. "cb" is the callback to
…		…
333	time, which might affect timers and time-outs.	354	time, which might affect timers and time-outs.
334		355
335	When this is the case, you can call this method, which will update	356	When this is the case, you can call this method, which will update
336	the event loop's idea of "current time".	357	the event loop's idea of "current time".
337		358
		359	A typical example would be a script in a web server (e.g.
		360	"mod_perl") - when mod_perl executes the script, then the event loop
		361	will have the wrong idea about the "current time" (being potentially
		362	far in the past, when the script ran the last time). In that case
		363	you should arrange a call to "AnyEvent->now_update" each time the
		364	web server process wakes up again (e.g. at the start of your script,
		365	or in a handler).
		366
338	Note that updating the time might cause some events to be handled.	367	Note that updating the time might cause some events to be handled.
339		368
340	SIGNAL WATCHERS	369	SIGNAL WATCHERS
		370	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		371
341	You can watch for signals using a signal watcher, "signal" is the signal	372	You can watch for signals using a signal watcher, "signal" is the signal
342	name in uppercase and without any "SIG" prefix, "cb" is the Perl	373	name in uppercase and without any "SIG" prefix, "cb" is the Perl
343	callback to be invoked whenever a signal occurs.	374	callback to be invoked whenever a signal occurs.
344		375
345	Although the callback might get passed parameters, their value and	376	Although the callback might get passed parameters, their value and
…		…
350	invocation, and callback invocation will be synchronous. Synchronous	381	invocation, and callback invocation will be synchronous. Synchronous
351	means that it might take a while until the signal gets handled by the	382	means that it might take a while until the signal gets handled by the
352	process, but it is guaranteed not to interrupt any other callbacks.	383	process, but it is guaranteed not to interrupt any other callbacks.
353		384
354	The main advantage of using these watchers is that you can share a	385	The main advantage of using these watchers is that you can share a
355	signal between multiple watchers.	386	signal between multiple watchers, and AnyEvent will ensure that signals
		387	will not interrupt your program at bad times.
356		388
357	This watcher might use %SIG, so programs overwriting those signals	389	This watcher might use %SIG (depending on the event loop used), so
358	directly will likely not work correctly.	390	programs overwriting those signals directly will likely not work
		391	correctly.
359		392
360	Example: exit on SIGINT	393	Example: exit on SIGINT
361		394
362	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	395	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
363		396
		397	Signal Races, Delays and Workarounds
		398	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		399	callbacks to signals in a generic way, which is a pity, as you cannot do
		400	race-free signal handling in perl, requiring C libraries for this.
		401	AnyEvent will try to do it's best, which means in some cases, signals
		402	will be delayed. The maximum time a signal might be delayed is specified
		403	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
		404	can be changed only before the first signal watcher is created, and
		405	should be left alone otherwise. This variable determines how often
		406	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		407	will cause fewer spurious wake-ups, which is better for power and CPU
		408	saving.
		409
		410	All these problems can be avoided by installing the optional
		411	Async::Interrupt module, which works with most event loops. It will not
		412	work with inherently broken event loops such as Event or Event::Lib (and
		413	not with POE currently, as POE does it's own workaround with one-second
		414	latency). For those, you just have to suffer the delays.
		415
364	CHILD PROCESS WATCHERS	416	CHILD PROCESS WATCHERS
		417	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		418
365	You can also watch on a child process exit and catch its exit status.	419	You can also watch on a child process exit and catch its exit status.
366		420
367	The child process is specified by the "pid" argument (if set to 0, it	421	The child process is specified by the "pid" argument (one some backends,
368	watches for any child process exit). The watcher will triggered only	422	using 0 watches for any child process exit, on others this will croak).
369	when the child process has finished and an exit status is available, not	423	The watcher will be triggered only when the child process has finished
370	on any trace events (stopped/continued).	424	and an exit status is available, not on any trace events
		425	(stopped/continued).
371		426
372	The callback will be called with the pid and exit status (as returned by	427	The callback will be called with the pid and exit status (as returned by
373	waitpid), so unlike other watcher types, you can rely on child watcher	428	waitpid), so unlike other watcher types, you can rely on child watcher
374	callback arguments.	429	callback arguments.
375		430
…		…
390	of when you start the watcher.	445	of when you start the watcher.
391		446
392	This means you cannot create a child watcher as the very first thing in	447	This means you cannot create a child watcher as the very first thing in
393	an AnyEvent program, you have to create at least one watcher before	448	an AnyEvent program, you have to create at least one watcher before
394	you "fork" the child (alternatively, you can call "AnyEvent::detect").	449	you "fork" the child (alternatively, you can call "AnyEvent::detect").
		450
		451	As most event loops do not support waiting for child events, they will
		452	be emulated by AnyEvent in most cases, in which the latency and race
		453	problems mentioned in the description of signal watchers apply.
395		454
396	Example: fork a process and wait for it	455	Example: fork a process and wait for it
397		456
398	my $done = AnyEvent->condvar;	457	my $done = AnyEvent->condvar;
399		458
…		…
410		469
411	# do something else, then wait for process exit	470	# do something else, then wait for process exit
412	$done->recv;	471	$done->recv;
413		472
414	IDLE WATCHERS	473	IDLE WATCHERS
		474	$w = AnyEvent->idle (cb => <callback>);
		475
415	Sometimes there is a need to do something, but it is not so important to	476	Sometimes there is a need to do something, but it is not so important to
416	do it instantly, but only when there is nothing better to do. This	477	do it instantly, but only when there is nothing better to do. This
417	"nothing better to do" is usually defined to be "no other events need	478	"nothing better to do" is usually defined to be "no other events need
418	attention by the event loop".	479	attention by the event loop".
419		480
…		…
444	}	505	}
445	});	506	});
446	});	507	});
447		508
448	CONDITION VARIABLES	509	CONDITION VARIABLES
		510	$cv = AnyEvent->condvar;
		511
		512	$cv->send (<list>);
		513	my @res = $cv->recv;
		514
449	If you are familiar with some event loops you will know that all of them	515	If you are familiar with some event loops you will know that all of them
450	require you to run some blocking "loop", "run" or similar function that	516	require you to run some blocking "loop", "run" or similar function that
451	will actively watch for new events and call your callbacks.	517	will actively watch for new events and call your callbacks.
452		518
453	AnyEvent is different, it expects somebody else to run the event loop	519	AnyEvent is slightly different: it expects somebody else to run the
454	and will only block when necessary (usually when told by the user).	520	event loop and will only block when necessary (usually when told by the
		521	user).
455		522
456	The instrument to do that is called a "condition variable", so called	523	The instrument to do that is called a "condition variable", so called
457	because they represent a condition that must become true.	524	because they represent a condition that must become true.
458		525
		526	Now is probably a good time to look at the examples further below.
		527
459	Condition variables can be created by calling the "AnyEvent->condvar"	528	Condition variables can be created by calling the "AnyEvent->condvar"
460	method, usually without arguments. The only argument pair allowed is	529	method, usually without arguments. The only argument pair allowed is
461
462	"cb", which specifies a callback to be called when the condition	530	"cb", which specifies a callback to be called when the condition
463	variable becomes true, with the condition variable as the first argument	531	variable becomes true, with the condition variable as the first argument
464	(but not the results).	532	(but not the results).
465		533
466	After creation, the condition variable is "false" until it becomes	534	After creation, the condition variable is "false" until it becomes
…		…
471	Condition variables are similar to callbacks, except that you can	539	Condition variables are similar to callbacks, except that you can
472	optionally wait for them. They can also be called merge points - points	540	optionally wait for them. They can also be called merge points - points
473	in time where multiple outstanding events have been processed. And yet	541	in time where multiple outstanding events have been processed. And yet
474	another way to call them is transactions - each condition variable can	542	another way to call them is transactions - each condition variable can
475	be used to represent a transaction, which finishes at some point and	543	be used to represent a transaction, which finishes at some point and
476	delivers a result.	544	delivers a result. And yet some people know them as "futures" - a
		545	promise to compute/deliver something that you can wait for.
477		546
478	Condition variables are very useful to signal that something has	547	Condition variables are very useful to signal that something has
479	finished, for example, if you write a module that does asynchronous http	548	finished, for example, if you write a module that does asynchronous http
480	requests, then a condition variable would be the ideal candidate to	549	requests, then a condition variable would be the ideal candidate to
481	signal the availability of results. The user can either act when the	550	signal the availability of results. The user can either act when the
…		…
515	after => 1,	584	after => 1,
516	cb => sub { $result_ready->send },	585	cb => sub { $result_ready->send },
517	);	586	);
518		587
519	# this "blocks" (while handling events) till the callback	588	# this "blocks" (while handling events) till the callback
520	# calls send	589	# calls ->send
521	$result_ready->recv;	590	$result_ready->recv;
522		591
523	Example: wait for a timer, but take advantage of the fact that condition	592	Example: wait for a timer, but take advantage of the fact that condition
524	variables are also code references.	593	variables are also callable directly.
525		594
526	my $done = AnyEvent->condvar;	595	my $done = AnyEvent->condvar;
527	my $delay = AnyEvent->timer (after => 5, cb => $done);	596	my $delay = AnyEvent->timer (after => 5, cb => $done);
528	$done->recv;	597	$done->recv;
529		598
…		…
535		604
536	...	605	...
537		606
538	my @info = $couchdb->info->recv;	607	my @info = $couchdb->info->recv;
539		608
540	And this is how you would just ste a callback to be called whenever the	609	And this is how you would just set a callback to be called whenever the
541	results are available:	610	results are available:
542		611
543	$couchdb->info->cb (sub {	612	$couchdb->info->cb (sub {
544	my @info = $_[0]->recv;	613	my @info = $_[0]->recv;
545	});	614	});
…		…
560		629
561	Any arguments passed to the "send" call will be returned by all	630	Any arguments passed to the "send" call will be returned by all
562	future "->recv" calls.	631	future "->recv" calls.
563		632
564	Condition variables are overloaded so one can call them directly (as	633	Condition variables are overloaded so one can call them directly (as
565	a code reference). Calling them directly is the same as calling	634	if they were a code reference). Calling them directly is the same as
566	"send". Note, however, that many C-based event loops do not handle	635	calling "send".
567	overloading, so as tempting as it may be, passing a condition
568	variable instead of a callback does not work. Both the pure perl and
569	EV loops support overloading, however, as well as all functions that
570	use perl to invoke a callback (as in AnyEvent::Socket and
571	AnyEvent::DNS for example).
572		636
573	$cv->croak ($error)	637	$cv->croak ($error)
574	Similar to send, but causes all call's to "->recv" to invoke	638	Similar to send, but causes all call's to "->recv" to invoke
575	"Carp::croak" with the given error message/object/scalar.	639	"Carp::croak" with the given error message/object/scalar.
576		640
577	This can be used to signal any errors to the condition variable	641	This can be used to signal any errors to the condition variable
578	user/consumer.	642	user/consumer. Doing it this way instead of calling "croak" directly
		643	delays the error detetcion, but has the overwhelmign advantage that
		644	it diagnoses the error at the place where the result is expected,
		645	and not deep in some event clalback without connection to the actual
		646	code causing the problem.
579		647
580	$cv->begin ([group callback])	648	$cv->begin ([group callback])
581	$cv->end	649	$cv->end
582	These two methods are EXPERIMENTAL and MIGHT CHANGE.
583
584	These two methods can be used to combine many transactions/events	650	These two methods can be used to combine many transactions/events
585	into one. For example, a function that pings many hosts in parallel	651	into one. For example, a function that pings many hosts in parallel
586	might want to use a condition variable for the whole process.	652	might want to use a condition variable for the whole process.
587		653
588	Every call to "->begin" will increment a counter, and every call to	654	Every call to "->begin" will increment a counter, and every call to
589	"->end" will decrement it. If the counter reaches 0 in "->end", the	655	"->end" will decrement it. If the counter reaches 0 in "->end", the
590	(last) callback passed to "begin" will be executed. That callback is	656	(last) callback passed to "begin" will be executed, passing the
591	supposed to call "->send", but that is not required. If no	657	condvar as first argument. That callback is supposed to call
		658	"->send", but that is not required. If no group callback was set,
592	callback was set, "send" will be called without any arguments.	659	"send" will be called without any arguments.
593		660
594	Let's clarify this with the ping example:	661	You can think of "$cv->send" giving you an OR condition (one call
		662	sends), while "$cv->begin" and "$cv->end" giving you an AND
		663	condition (all "begin" calls must be "end"'ed before the condvar
		664	sends).
		665
		666	Let's start with a simple example: you have two I/O watchers (for
		667	example, STDOUT and STDERR for a program), and you want to wait for
		668	both streams to close before activating a condvar:
595		669
596	my $cv = AnyEvent->condvar;	670	my $cv = AnyEvent->condvar;
597		671
		672	$cv->begin; # first watcher
		673	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		674	defined sysread $fh1, my $buf, 4096
		675	or $cv->end;
		676	});
		677
		678	$cv->begin; # second watcher
		679	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		680	defined sysread $fh2, my $buf, 4096
		681	or $cv->end;
		682	});
		683
		684	$cv->recv;
		685
		686	This works because for every event source (EOF on file handle),
		687	there is one call to "begin", so the condvar waits for all calls to
		688	"end" before sending.
		689
		690	The ping example mentioned above is slightly more complicated, as
		691	the there are results to be passwd back, and the number of tasks
		692	that are begung can potentially be zero:
		693
		694	my $cv = AnyEvent->condvar;
		695
598	my %result;	696	my %result;
599	$cv->begin (sub { $cv->send (\%result) });	697	$cv->begin (sub { shift->send (\%result) });
600		698
601	for my $host (@list_of_hosts) {	699	for my $host (@list_of_hosts) {
602	$cv->begin;	700	$cv->begin;
603	ping_host_then_call_callback $host, sub {	701	ping_host_then_call_callback $host, sub {
604	$result{$host} = ...;	702	$result{$host} = ...;
…		…
619	the loop, which serves two important purposes: first, it sets the	717	the loop, which serves two important purposes: first, it sets the
620	callback to be called once the counter reaches 0, and second, it	718	callback to be called once the counter reaches 0, and second, it
621	ensures that "send" is called even when "no" hosts are being pinged	719	ensures that "send" is called even when "no" hosts are being pinged
622	(the loop doesn't execute once).	720	(the loop doesn't execute once).
623		721
624	This is the general pattern when you "fan out" into multiple	722	This is the general pattern when you "fan out" into multiple (but
625	subrequests: use an outer "begin"/"end" pair to set the callback and	723	potentially none) subrequests: use an outer "begin"/"end" pair to
626	ensure "end" is called at least once, and then, for each subrequest	724	set the callback and ensure "end" is called at least once, and then,
627	you start, call "begin" and for each subrequest you finish, call	725	for each subrequest you start, call "begin" and for each subrequest
628	"end".	726	you finish, call "end".
629		727
630	METHODS FOR CONSUMERS	728	METHODS FOR CONSUMERS
631	These methods should only be used by the consuming side, i.e. the code	729	These methods should only be used by the consuming side, i.e. the code
632	awaits the condition.	730	awaits the condition.
633		731
…		…
642	function will call "croak".	740	function will call "croak".
643		741
644	In list context, all parameters passed to "send" will be returned,	742	In list context, all parameters passed to "send" will be returned,
645	in scalar context only the first one will be returned.	743	in scalar context only the first one will be returned.
646		744
		745	Note that doing a blocking wait in a callback is not supported by
		746	any event loop, that is, recursive invocation of a blocking "->recv"
		747	is not allowed, and the "recv" call will "croak" if such a condition
		748	is detected. This condition can be slightly loosened by using
		749	Coro::AnyEvent, which allows you to do a blocking "->recv" from any
		750	thread that doesn't run the event loop itself.
		751
647	Not all event models support a blocking wait - some die in that case	752	Not all event models support a blocking wait - some die in that case
648	(programs might want to do that to stay interactive), so *if you are	753	(programs might want to do that to stay interactive), so *if you are
649	using this from a module, never require a blocking wait*, but let	754	using this from a module, never require a blocking wait*. Instead,
650	the caller decide whether the call will block or not (for example,	755	let the caller decide whether the call will block or not (for
651	by coupling condition variables with some kind of request results	756	example, by coupling condition variables with some kind of request
652	and supporting callbacks so the caller knows that getting the result	757	results and supporting callbacks so the caller knows that getting
653	will not block, while still supporting blocking waits if the caller	758	the result will not block, while still supporting blocking waits if
654	so desires).	759	the caller so desires).
655
656	Another reason never to "->recv" in a module is that you cannot
657	sensibly have two "->recv"'s in parallel, as that would require
658	multiple interpreters or coroutines/threads, none of which
659	"AnyEvent" can supply.
660
661	The Coro module, however, can and does supply coroutines and, in
662	fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe
663	versions and also integrates coroutines into AnyEvent, making
664	blocking "->recv" calls perfectly safe as long as they are done from
665	another coroutine (one that doesn't run the event loop).
666		760
667	You can ensure that "-recv" never blocks by setting a callback and	761	You can ensure that "-recv" never blocks by setting a callback and
668	only calling "->recv" from within that callback (or at a later	762	only calling "->recv" from within that callback (or at a later
669	time). This will work even when the event loop does not support	763	time). This will work even when the event loop does not support
670	blocking waits otherwise.	764	blocking waits otherwise.
…		…
675		769
676	$cb = $cv->cb ($cb->($cv))	770	$cb = $cv->cb ($cb->($cv))
677	This is a mutator function that returns the callback set and	771	This is a mutator function that returns the callback set and
678	optionally replaces it before doing so.	772	optionally replaces it before doing so.
679		773
680	The callback will be called when the condition becomes "true", i.e.	774	The callback will be called when the condition becomes (or already
681	when "send" or "croak" are called, with the only argument being the	775	was) "true", i.e. when "send" or "croak" are called (or were
682	condition variable itself. Calling "recv" inside the callback or at	776	called), with the only argument being the condition variable itself.
		777	Calling "recv" inside the callback or at any later time is
683	any later time is guaranteed not to block.	778	guaranteed not to block.
		779
		780	SUPPORTED EVENT LOOPS/BACKENDS
		781	The available backend classes are (every class has its own manpage):
		782
		783	Backends that are autoprobed when no other event loop can be found.
		784	EV is the preferred backend when no other event loop seems to be in
		785	use. If EV is not installed, then AnyEvent will fall back to its own
		786	pure-perl implementation, which is available everywhere as it comes
		787	with AnyEvent itself.
		788
		789	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		790	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		791
		792	Backends that are transparently being picked up when they are used.
		793	These will be used when they are currently loaded when the first
		794	watcher is created, in which case it is assumed that the application
		795	is using them. This means that AnyEvent will automatically pick the
		796	right backend when the main program loads an event module before
		797	anything starts to create watchers. Nothing special needs to be done
		798	by the main program.
		799
		800	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		801	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		802	AnyEvent::Impl::Tk based on Tk, very broken.
		803	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		804	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		805	AnyEvent::Impl::Irssi used when running within irssi.
		806
		807	Backends with special needs.
		808	Qt requires the Qt::Application to be instantiated first, but will
		809	otherwise be picked up automatically. As long as the main program
		810	instantiates the application before any AnyEvent watchers are
		811	created, everything should just work.
		812
		813	AnyEvent::Impl::Qt based on Qt.
		814
		815	Support for IO::Async can only be partial, as it is too broken and
		816	architecturally limited to even support the AnyEvent API. It also is
		817	the only event loop that needs the loop to be set explicitly, so it
		818	can only be used by a main program knowing about AnyEvent. See
		819	AnyEvent::Impl::Async for the gory details.
		820
		821	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		822
		823	Event loops that are indirectly supported via other backends.
		824	Some event loops can be supported via other modules:
		825
		826	There is no direct support for WxWidgets (Wx) or Prima.
		827
		828	WxWidgets has no support for watching file handles. However, you can
		829	use WxWidgets through the POE adaptor, as POE has a Wx backend that
		830	simply polls 20 times per second, which was considered to be too
		831	horrible to even consider for AnyEvent.
		832
		833	Prima is not supported as nobody seems to be using it, but it has a
		834	POE backend, so it can be supported through POE.
		835
		836	AnyEvent knows about both Prima and Wx, however, and will try to
		837	load POE when detecting them, in the hope that POE will pick them
		838	up, in which case everything will be automatic.
684		839
685	GLOBAL VARIABLES AND FUNCTIONS	840	GLOBAL VARIABLES AND FUNCTIONS
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
686	$AnyEvent::MODEL	844	$AnyEvent::MODEL
687	Contains "undef" until the first watcher is being created. Then it	845	Contains "undef" until the first watcher is being created, before
		846	the backend has been autodetected.
		847
688	contains the event model that is being used, which is the name of	848	Afterwards it contains the event model that is being used, which is
689	the Perl class implementing the model. This class is usually one of	849	the name of the Perl class implementing the model. This class is
690	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	850	usually one of the "AnyEvent::Impl:xxx" modules, but can be any
691	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	851	other class in the case AnyEvent has been extended at runtime (e.g.
692		852	in rxvt-unicode it will be "urxvt::anyevent").
693	The known classes so far are:
694
695	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
696	AnyEvent::Impl::Event based on Event, second best choice.
697	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
698	AnyEvent::Impl::Glib based on Glib, third-best choice.
699	AnyEvent::Impl::Tk based on Tk, very bad choice.
700	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
701	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
702	AnyEvent::Impl::POE based on POE, not generic enough for full support.
703
704	# warning, support for IO::Async is only partial, as it is too broken
705	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
706	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
707
708	There is no support for WxWidgets, as WxWidgets has no support for
709	watching file handles. However, you can use WxWidgets through the
710	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
711	second, which was considered to be too horrible to even consider for
712	AnyEvent. Likewise, other POE backends can be used by AnyEvent by
713	using it's adaptor.
714
715	AnyEvent knows about Prima and Wx and will try to use POE when
716	autodetecting them.
717		853
718	AnyEvent::detect	854	AnyEvent::detect
719	Returns $AnyEvent::MODEL, forcing autodetection of the event model	855	Returns $AnyEvent::MODEL, forcing autodetection of the event model
720	if necessary. You should only call this function right before you	856	if necessary. You should only call this function right before you
721	would have created an AnyEvent watcher anyway, that is, as late as	857	would have created an AnyEvent watcher anyway, that is, as late as
722	possible at runtime.	858	possible at runtime, and not e.g. while initialising of your module.
		859
		860	If you need to do some initialisation before AnyEvent watchers are
		861	created, use "post_detect".
723		862
724	$guard = AnyEvent::post_detect { BLOCK }	863	$guard = AnyEvent::post_detect { BLOCK }
725	Arranges for the code block to be executed as soon as the event	864	Arranges for the code block to be executed as soon as the event
726	model is autodetected (or immediately if this has already happened).	865	model is autodetected (or immediately if this has already happened).
727		866
		867	The block will be executed after the actual backend has been
		868	detected ($AnyEvent::MODEL is set), but before any watchers have
		869	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
		870	other initialisations - see the sources of AnyEvent::Strict or
		871	AnyEvent::AIO to see how this is used.
		872
		873	The most common usage is to create some global watchers, without
		874	forcing event module detection too early, for example, AnyEvent::AIO
		875	creates and installs the global IO::AIO watcher in a "post_detect"
		876	block to avoid autodetecting the event module at load time.
		877
728	If called in scalar or list context, then it creates and returns an	878	If called in scalar or list context, then it creates and returns an
729	object that automatically removes the callback again when it is	879	object that automatically removes the callback again when it is
		880	destroyed (or "undef" when the hook was immediately executed). See
730	destroyed. See Coro::BDB for a case where this is useful.	881	AnyEvent::AIO for a case where this is useful.
		882
		883	Example: Create a watcher for the IO::AIO module and store it in
		884	$WATCHER. Only do so after the event loop is initialised, though.
		885
		886	our WATCHER;
		887
		888	my $guard = AnyEvent::post_detect {
		889	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		890	};
		891
		892	# the \|\|= is important in case post_detect immediately runs the block,
		893	# as to not clobber the newly-created watcher. assigning both watcher and
		894	# post_detect guard to the same variable has the advantage of users being
		895	# able to just C<undef $WATCHER> if the watcher causes them grief.
		896
		897	$WATCHER \|\|= $guard;
731		898
732	@AnyEvent::post_detect	899	@AnyEvent::post_detect
733	If there are any code references in this array (you can "push" to it	900	If there are any code references in this array (you can "push" to it
734	before or after loading AnyEvent), then they will called directly	901	before or after loading AnyEvent), then they will called directly
735	after the event loop has been chosen.	902	after the event loop has been chosen.
736		903
737	You should check $AnyEvent::MODEL before adding to this array,	904	You should check $AnyEvent::MODEL before adding to this array,
738	though: if it contains a true value then the event loop has already	905	though: if it is defined then the event loop has already been
739	been detected, and the array will be ignored.	906	detected, and the array will be ignored.
740		907
741	Best use "AnyEvent::post_detect { BLOCK }" instead.	908	Best use "AnyEvent::post_detect { BLOCK }" when your application
		909	allows it,as it takes care of these details.
		910
		911	This variable is mainly useful for modules that can do something
		912	useful when AnyEvent is used and thus want to know when it is
		913	initialised, but do not need to even load it by default. This array
		914	provides the means to hook into AnyEvent passively, without loading
		915	it.
742		916
743	WHAT TO DO IN A MODULE	917	WHAT TO DO IN A MODULE
744	As a module author, you should "use AnyEvent" and call AnyEvent methods	918	As a module author, you should "use AnyEvent" and call AnyEvent methods
745	freely, but you should not load a specific event module or rely on it.	919	freely, but you should not load a specific event module or rely on it.
746		920
…		…
797	variable somewhere, waiting for it, and sending it when the program	971	variable somewhere, waiting for it, and sending it when the program
798	should exit cleanly.	972	should exit cleanly.
799		973
800	OTHER MODULES	974	OTHER MODULES
801	The following is a non-exhaustive list of additional modules that use	975	The following is a non-exhaustive list of additional modules that use
802	AnyEvent and can therefore be mixed easily with other AnyEvent modules	976	AnyEvent as a client and can therefore be mixed easily with other
803	in the same program. Some of the modules come with AnyEvent, some are	977	AnyEvent modules and other event loops in the same program. Some of the
804	available via CPAN.	978	modules come with AnyEvent, most are available via CPAN.
805		979
806	AnyEvent::Util	980	AnyEvent::Util
807	Contains various utility functions that replace often-used but	981	Contains various utility functions that replace often-used but
808	blocking functions such as "inet_aton" by event-/callback-based	982	blocking functions such as "inet_aton" by event-/callback-based
809	versions.	983	versions.
…		…
815	more.	989	more.
816		990
817	AnyEvent::Handle	991	AnyEvent::Handle
818	Provide read and write buffers, manages watchers for reads and	992	Provide read and write buffers, manages watchers for reads and
819	writes, supports raw and formatted I/O, I/O queued and fully	993	writes, supports raw and formatted I/O, I/O queued and fully
820	transparent and non-blocking SSL/TLS.	994	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
821		995
822	AnyEvent::DNS	996	AnyEvent::DNS
823	Provides rich asynchronous DNS resolver capabilities.	997	Provides rich asynchronous DNS resolver capabilities.
824		998
825	AnyEvent::HTTP	999	AnyEvent::HTTP
…		…
846		1020
847	AnyEvent::GPSD	1021	AnyEvent::GPSD
848	A non-blocking interface to gpsd, a daemon delivering GPS	1022	A non-blocking interface to gpsd, a daemon delivering GPS
849	information.	1023	information.
850		1024
		1025	AnyEvent::IRC
		1026	AnyEvent based IRC client module family (replacing the older
		1027	Net::IRC3).
		1028
		1029	AnyEvent::XMPP
		1030	AnyEvent based XMPP (Jabber protocol) module family (replacing the
		1031	older Net::XMPP2>.
		1032
851	AnyEvent::IGS	1033	AnyEvent::IGS
852	A non-blocking interface to the Internet Go Server protocol (used by	1034	A non-blocking interface to the Internet Go Server protocol (used by
853	App::IGS).	1035	App::IGS).
854		1036
855	AnyEvent::IRC
856	AnyEvent based IRC client module family (replacing the older
857	Net::IRC3).
858
859	Net::XMPP2
860	AnyEvent based XMPP (Jabber protocol) module family.
861
862	Net::FCP	1037	Net::FCP
863	AnyEvent-based implementation of the Freenet Client Protocol,	1038	AnyEvent-based implementation of the Freenet Client Protocol,
864	birthplace of AnyEvent.	1039	birthplace of AnyEvent.
865		1040
866	Event::ExecFlow	1041	Event::ExecFlow
867	High level API for event-based execution flow control.	1042	High level API for event-based execution flow control.
868		1043
869	Coro	1044	Coro
870	Has special support for AnyEvent via Coro::AnyEvent.	1045	Has special support for AnyEvent via Coro::AnyEvent.
871		1046
872	IO::Lambda	1047	SIMPLIFIED AE API
873	The lambda approach to I/O - don't ask, look there. Can use	1048	Starting with version 5.0, AnyEvent officially supports a second, much
874	AnyEvent.	1049	simpler, API that is designed to reduce the calling, typing and memory
		1050	overhead.
		1051
		1052	See the AE manpage for details.
875		1053
876	ERROR AND EXCEPTION HANDLING	1054	ERROR AND EXCEPTION HANDLING
877	In general, AnyEvent does not do any error handling - it relies on the	1055	In general, AnyEvent does not do any error handling - it relies on the
878	caller to do that if required. The AnyEvent::Strict module (see also the	1056	caller to do that if required. The AnyEvent::Strict module (see also the
879	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict	1057	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
…		…
907	by "PERL_ANYEVENT_MODEL".	1085	by "PERL_ANYEVENT_MODEL".
908		1086
909	When set to 2 or higher, cause AnyEvent to report to STDERR which	1087	When set to 2 or higher, cause AnyEvent to report to STDERR which
910	event model it chooses.	1088	event model it chooses.
911		1089
		1090	When set to 8 or higher, then AnyEvent will report extra information
		1091	on which optional modules it loads and how it implements certain
		1092	features.
		1093
912	"PERL_ANYEVENT_STRICT"	1094	"PERL_ANYEVENT_STRICT"
913	AnyEvent does not do much argument checking by default, as thorough	1095	AnyEvent does not do much argument checking by default, as thorough
914	argument checking is very costly. Setting this variable to a true	1096	argument checking is very costly. Setting this variable to a true
915	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1097	value will cause AnyEvent to load "AnyEvent::Strict" and then to
916	thoroughly check the arguments passed to most method calls. If it	1098	thoroughly check the arguments passed to most method calls. If it
917	finds any problems, it will croak.	1099	finds any problems, it will croak.
918		1100
919	In other words, enables "strict" mode.	1101	In other words, enables "strict" mode.
920		1102
921	Unlike "use strict", it is definitely recommended to keep it off in	1103	Unlike "use strict" (or it's modern cousin, "use common::sense", it
922	production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment	1104	is definitely recommended to keep it off in production. Keeping
		1105	"PERL_ANYEVENT_STRICT=1" in your environment while developing
923	while developing programs can be very useful, however.	1106	programs can be very useful, however.
924		1107
925	"PERL_ANYEVENT_MODEL"	1108	"PERL_ANYEVENT_MODEL"
926	This can be used to specify the event model to be used by AnyEvent,	1109	This can be used to specify the event model to be used by AnyEvent,
927	before auto detection and -probing kicks in. It must be a string	1110	before auto detection and -probing kicks in. It must be a string
928	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1111	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
…		…
969	EDNS0 in its DNS requests.	1152	EDNS0 in its DNS requests.
970		1153
971	"PERL_ANYEVENT_MAX_FORKS"	1154	"PERL_ANYEVENT_MAX_FORKS"
972	The maximum number of child processes that	1155	The maximum number of child processes that
973	"AnyEvent::Util::fork_call" will create in parallel.	1156	"AnyEvent::Util::fork_call" will create in parallel.
		1157
		1158	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
		1159	The default value for the "max_outstanding" parameter for the
		1160	default DNS resolver - this is the maximum number of parallel DNS
		1161	requests that are sent to the DNS server.
		1162
		1163	"PERL_ANYEVENT_RESOLV_CONF"
		1164	The file to use instead of /etc/resolv.conf (or OS-specific
		1165	configuration) in the default resolver. When set to the empty
		1166	string, no default config will be used.
		1167
		1168	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
		1169	When neither "ca_file" nor "ca_path" was specified during
		1170	AnyEvent::TLS context creation, and either of these environment
		1171	variables exist, they will be used to specify CA certificate
		1172	locations instead of a system-dependent default.
		1173
		1174	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
		1175	When these are set to 1, then the respective modules are not loaded.
		1176	Mostly good for testing AnyEvent itself.
974		1177
975	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1178	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
976	This is an advanced topic that you do not normally need to use AnyEvent	1179	This is an advanced topic that you do not normally need to use AnyEvent
977	in a module. This section is only of use to event loop authors who want	1180	in a module. This section is only of use to event loop authors who want
978	to provide AnyEvent compatibility.	1181	to provide AnyEvent compatibility.
…		…
1033	warn "read: $input\n"; # output what has been read	1236	warn "read: $input\n"; # output what has been read
1034	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1237	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1035	},	1238	},
1036	);	1239	);
1037		1240
1038	my $time_watcher; # can only be used once
1039
1040	sub new_timer {
1041	$timer = AnyEvent->timer (after => 1, cb => sub {	1241	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1042	warn "timeout\n"; # print 'timeout' about every second	1242	warn "timeout\n"; # print 'timeout' at most every second
1043	&new_timer; # and restart the time
1044	});
1045	}	1243	});
1046
1047	new_timer; # create first timer
1048		1244
1049	$cv->recv; # wait until user enters /^q/i	1245	$cv->recv; # wait until user enters /^q/i
1050		1246
1051	REAL-WORLD EXAMPLE	1247	REAL-WORLD EXAMPLE
1052	Consider the Net::FCP module. It features (among others) the following	1248	Consider the Net::FCP module. It features (among others) the following
…		…
1179	through AnyEvent. The benchmark creates a lot of timers (with a zero	1375	through AnyEvent. The benchmark creates a lot of timers (with a zero
1180	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1376	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1181	which it is), lets them fire exactly once and destroys them again.	1377	which it is), lets them fire exactly once and destroys them again.
1182		1378
1183	Source code for this benchmark is found as eg/bench in the AnyEvent	1379	Source code for this benchmark is found as eg/bench in the AnyEvent
1184	distribution.	1380	distribution. It uses the AE interface, which makes a real difference
		1381	for the EV and Perl backends only.
1185		1382
1186	Explanation of the columns	1383	Explanation of the columns
1187	watcher is the number of event watchers created/destroyed. Since	1384	watcher is the number of event watchers created/destroyed. Since
1188	different event models feature vastly different performances, each event	1385	different event models feature vastly different performances, each event
1189	loop was given a number of watchers so that overall runtime is	1386	loop was given a number of watchers so that overall runtime is
…		…
1208	destroy is the time, in microseconds, that it takes to destroy a	1405	destroy is the time, in microseconds, that it takes to destroy a
1209	single watcher.	1406	single watcher.
1210		1407
1211	Results	1408	Results
1212	name watchers bytes create invoke destroy comment	1409	name watchers bytes create invoke destroy comment
1213	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	1410	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1214	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1411	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1215	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1412	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1216	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1413	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1217	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1414	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1218	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1415	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
1219	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll	1416	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
1220	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll	1417	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1221	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1418	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1222	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1419	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1223	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1420	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1224	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1421	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1225		1422
1226	Discussion	1423	Discussion
1227	The benchmark does not measure scalability of the event loop very	1424	The benchmark does not measure scalability of the event loop very
1228	well. For example, a select-based event loop (such as the pure perl one)	1425	well. For example, a select-based event loop (such as the pure perl one)
1229	can never compete with an event loop that uses epoll when the number of	1426	can never compete with an event loop that uses epoll when the number of
…		…
1240	benchmark machine, handling an event takes roughly 1600 CPU cycles with	1437	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1241	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000	1438	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1242	CPU cycles with POE.	1439	CPU cycles with POE.
1243		1440
1244	"EV" is the sole leader regarding speed and memory use, which are both	1441	"EV" is the sole leader regarding speed and memory use, which are both
1245	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1442	maximal/minimal, respectively. When using the AE API there is zero
		1443	overhead (when going through the AnyEvent API create is about 5-6 times
		1444	slower, with other times being equal, so still uses far less memory than
1246	far less memory than any other event loop and is still faster than Event	1445	any other event loop and is still faster than Event natively).
1247	natively.
1248		1446
1249	The pure perl implementation is hit in a few sweet spots (both the	1447	The pure perl implementation is hit in a few sweet spots (both the
1250	constant timeout and the use of a single fd hit optimisations in the	1448	constant timeout and the use of a single fd hit optimisations in the
1251	perl interpreter and the backend itself). Nevertheless this shows that	1449	perl interpreter and the backend itself). Nevertheless this shows that
1252	it adds very little overhead in itself. Like any select-based backend	1450	it adds very little overhead in itself. Like any select-based backend
…		…
1322	In this benchmark, we use 10000 socket pairs (20000 sockets), of which	1520	In this benchmark, we use 10000 socket pairs (20000 sockets), of which
1323	100 (1%) are active. This mirrors the activity of large servers with	1521	100 (1%) are active. This mirrors the activity of large servers with
1324	many connections, most of which are idle at any one point in time.	1522	many connections, most of which are idle at any one point in time.
1325		1523
1326	Source code for this benchmark is found as eg/bench2 in the AnyEvent	1524	Source code for this benchmark is found as eg/bench2 in the AnyEvent
1327	distribution.	1525	distribution. It uses the AE interface, which makes a real difference
		1526	for the EV and Perl backends only.
1328		1527
1329	Explanation of the columns	1528	Explanation of the columns
1330	sockets is the number of sockets, and twice the number of "servers"	1529	sockets is the number of sockets, and twice the number of "servers"
1331	(as each server has a read and write socket end).	1530	(as each server has a read and write socket end).
1332		1531
…		…
1338	forwarding it to another server. This includes deleting the old timeout	1537	forwarding it to another server. This includes deleting the old timeout
1339	and creating a new one that moves the timeout into the future.	1538	and creating a new one that moves the timeout into the future.
1340		1539
1341	Results	1540	Results
1342	name sockets create request	1541	name sockets create request
1343	EV 20000 69.01 11.16	1542	EV 20000 62.66 7.99
1344	Perl 20000 73.32 35.87	1543	Perl 20000 68.32 32.64
1345	IOAsync 20000 157.00 98.14 epoll	1544	IOAsync 20000 174.06 101.15 epoll
1346	IOAsync 20000 159.31 616.06 poll	1545	IOAsync 20000 174.67 610.84 poll
1347	Event 20000 212.62 257.32	1546	Event 20000 202.69 242.91
1348	Glib 20000 651.16 1896.30	1547	Glib 20000 557.01 1689.52
1349	POE 20000 349.67 12317.24 uses POE::Loop::Event	1548	POE 20000 341.54 12086.32 uses POE::Loop::Event
1350		1549
1351	Discussion	1550	Discussion
1352	This benchmark does measure scalability and overall performance of the	1551	This benchmark does measure scalability and overall performance of the
1353	particular event loop.	1552	particular event loop.
1354		1553
…		…
1467	As you can see, the AnyEvent + EV combination even beats the	1666	As you can see, the AnyEvent + EV combination even beats the
1468	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl	1667	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1469	backend easily beats IO::Lambda and POE.	1668	backend easily beats IO::Lambda and POE.
1470		1669
1471	And even the 100% non-blocking version written using the high-level (and	1670	And even the 100% non-blocking version written using the high-level (and
1472	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a	1671	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda
1473	large margin, even though it does all of DNS, tcp-connect and socket I/O	1672	higher level ("unoptimised") abstractions by a large margin, even though
1474	in a non-blocking way.	1673	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1475		1674
1476	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and	1675	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
1477	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are	1676	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1478	part of the IO::lambda distribution and were used without any changes.	1677	part of the IO::Lambda distribution and were used without any changes.
1479		1678
1480	SIGNALS	1679	SIGNALS
1481	AnyEvent currently installs handlers for these signals:	1680	AnyEvent currently installs handlers for these signals:
1482		1681
1483	SIGCHLD	1682	SIGCHLD
1484	A handler for "SIGCHLD" is installed by AnyEvent's child watcher	1683	A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1485	emulation for event loops that do not support them natively. Also,	1684	emulation for event loops that do not support them natively. Also,
1486	some event loops install a similar handler.	1685	some event loops install a similar handler.
1487		1686
1488	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent	1687	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE,
1489	will reset it to default, to avoid losing child exit statuses.	1688	then AnyEvent will reset it to default, to avoid losing child exit
		1689	statuses.
1490		1690
1491	SIGPIPE	1691	SIGPIPE
1492	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is	1692	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1493	"undef" when AnyEvent gets loaded.	1693	"undef" when AnyEvent gets loaded.
1494		1694
…		…
1502	it is that this way, the handler will be restored to defaults on	1702	it is that this way, the handler will be restored to defaults on
1503	exec.	1703	exec.
1504		1704
1505	Feel free to install your own handler, or reset it to defaults.	1705	Feel free to install your own handler, or reset it to defaults.
1506		1706
		1707	RECOMMENDED/OPTIONAL MODULES
		1708	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		1709	it's built-in modules) are required to use it.
		1710
		1711	That does not mean that AnyEvent won't take advantage of some additional
		1712	modules if they are installed.
		1713
		1714	This section epxlains which additional modules will be used, and how
		1715	they affect AnyEvent's operetion.
		1716
		1717	Async::Interrupt
		1718	This slightly arcane module is used to implement fast signal
		1719	handling: To my knowledge, there is no way to do completely
		1720	race-free and quick signal handling in pure perl. To ensure that
		1721	signals still get delivered, AnyEvent will start an interval timer
		1722	to wake up perl (and catch the signals) with some delay (default is
		1723	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
		1724
		1725	If this module is available, then it will be used to implement
		1726	signal catching, which means that signals will not be delayed, and
		1727	the event loop will not be interrupted regularly, which is more
		1728	efficient (And good for battery life on laptops).
		1729
		1730	This affects not just the pure-perl event loop, but also other event
		1731	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
		1732
		1733	Some event loops (POE, Event, Event::Lib) offer signal watchers
		1734	natively, and either employ their own workarounds (POE) or use
		1735	AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
		1736	Installing Async::Interrupt does nothing for those backends.
		1737
		1738	EV This module isn't really "optional", as it is simply one of the
		1739	backend event loops that AnyEvent can use. However, it is simply the
		1740	best event loop available in terms of features, speed and stability:
		1741	It supports the AnyEvent API optimally, implements all the watcher
		1742	types in XS, does automatic timer adjustments even when no monotonic
		1743	clock is available, can take avdantage of advanced kernel interfaces
		1744	such as "epoll" and "kqueue", and is the fastest backend by far.
		1745	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
		1746	Glib::EV).
		1747
		1748	Guard
		1749	The guard module, when used, will be used to implement
		1750	"AnyEvent::Util::guard". This speeds up guards considerably (and
		1751	uses a lot less memory), but otherwise doesn't affect guard
		1752	operation much. It is purely used for performance.
		1753
		1754	JSON and JSON::XS
		1755	One of these modules is required when you want to read or write JSON
		1756	data via AnyEvent::Handle. It is also written in pure-perl, but can
		1757	take advantage of the ultra-high-speed JSON::XS module when it is
		1758	installed.
		1759
		1760	In fact, AnyEvent::Handle will use JSON::XS by default if it is
		1761	installed.
		1762
		1763	Net::SSLeay
		1764	Implementing TLS/SSL in Perl is certainly interesting, but not very
		1765	worthwhile: If this module is installed, then AnyEvent::Handle (with
		1766	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
		1767
		1768	Time::HiRes
		1769	This module is part of perl since release 5.008. It will be used
		1770	when the chosen event library does not come with a timing source on
		1771	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will
		1772	additionally use it to try to use a monotonic clock for timing
		1773	stability.
		1774
1507	FORK	1775	FORK
1508	Most event libraries are not fork-safe. The ones who are usually are	1776	Most event libraries are not fork-safe. The ones who are usually are
1509	because they rely on inefficient but fork-safe "select" or "poll" calls.	1777	because they rely on inefficient but fork-safe "select" or "poll" calls.
1510	Only EV is fully fork-aware.	1778	Only EV is fully fork-aware.
1511		1779
1512	If you have to fork, you must either do so before creating your first	1780	If you have to fork, you must either do so before creating your first
1513	watcher OR you must not use AnyEvent at all in the child.	1781	watcher OR you must not use AnyEvent at all in the child OR you must do
		1782	something completely out of the scope of AnyEvent.
1514		1783
1515	SECURITY CONSIDERATIONS	1784	SECURITY CONSIDERATIONS
1516	AnyEvent can be forced to load any event model via	1785	AnyEvent can be forced to load any event model via
1517	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1786	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1518	to execute arbitrary code or directly gain access, it can easily be used	1787	to execute arbitrary code or directly gain access, it can easily be used
…		…
1549	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1818	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1550	Event::Lib, Qt, POE.	1819	Event::Lib, Qt, POE.
1551		1820
1552	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1821	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1553	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1822	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1554	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1823	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		1824	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1555		1825
1556	Non-blocking file handles, sockets, TCP clients and servers:	1826	Non-blocking file handles, sockets, TCP clients and servers:
1557	AnyEvent::Handle, AnyEvent::Socket.	1827	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1558		1828
1559	Asynchronous DNS: AnyEvent::DNS.	1829	Asynchronous DNS: AnyEvent::DNS.
1560		1830
1561	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1831	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1562		1832
1563	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.	1833	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
		1834	AnyEvent::HTTP.
1564		1835
1565	AUTHOR	1836	AUTHOR
1566	Marc Lehmann <schmorp@schmorp.de>	1837	Marc Lehmann <schmorp@schmorp.de>
1567	http://home.schmorp.de/	1838	http://home.schmorp.de/
1568		1839

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Revision 1.56 by root, Thu Nov 19 01:55:57 2009 UTC