[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.33 by root, Thu Oct 30 03:43:13 2008 UTC vs.
Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC

…		…
1	NAME	1	NAME
2	AnyEvent - provide framework for multiple event loops	2	AnyEvent - provide framework for multiple event loops
3		3
4	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event	4	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
5	loops	5	event loops.
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 { ... });
11		12
		13	# one-shot or repeating timers
12	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	14	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
13	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	15	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
14		16
15	print AnyEvent->now; # prints current event loop time	17	print AnyEvent->now; # prints current event loop time
16	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	18	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
17		19
		20	# POSIX signal
18	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	21	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
19		22
		23	# child process exit
20	my $w = AnyEvent->child (pid => $pid, cb => sub {	24	my $w = AnyEvent->child (pid => $pid, cb => sub {
21	my ($pid, $status) = @_;	25	my ($pid, $status) = @_;
22	...	26	...
23	});	27	});
		28
		29	# called when event loop idle (if applicable)
		30	my $w = AnyEvent->idle (cb => sub { ... });
24		31
25	my $w = AnyEvent->condvar; # stores whether a condition was flagged	32	my $w = AnyEvent->condvar; # stores whether a condition was flagged
26	$w->send; # wake up current and all future recv's	33	$w->send; # wake up current and all future recv's
27	$w->recv; # enters "main loop" till $condvar gets ->send	34	$w->recv; # enters "main loop" till $condvar gets ->send
28	# use a condvar in callback mode:	35	# use a condvar in callback mode:
132	These watchers are normal Perl objects with normal Perl lifetime. After	139	These watchers are normal Perl objects with normal Perl lifetime. After
133	creating a watcher it will immediately "watch" for events and invoke the	140	creating a watcher it will immediately "watch" for events and invoke the
134	callback when the event occurs (of course, only when the event model is	141	callback when the event occurs (of course, only when the event model is
135	in control).	142	in control).
136		143
		144	Note that callbacks must not permanently change global variables
		145	potentially in use by the event loop (such as $_ or $[) and that
		146	callbacks must not "die". The former is good programming practise in
		147	Perl and the latter stems from the fact that exception handling differs
		148	widely between event loops.
		149
137	To disable the watcher you have to destroy it (e.g. by setting the	150	To disable the watcher you have to destroy it (e.g. by setting the
138	variable you store it in to "undef" or otherwise deleting all references	151	variable you store it in to "undef" or otherwise deleting all references
139	to it).	152	to it).
140		153
141	All watchers are created by calling a method on the "AnyEvent" class.	154	All watchers are created by calling a method on the "AnyEvent" class.
…		…
156		169
157	I/O WATCHERS	170	I/O WATCHERS
158	You can create an I/O watcher by calling the "AnyEvent->io" method with	171	You can create an I/O watcher by calling the "AnyEvent->io" method with
159	the following mandatory key-value pairs as arguments:	172	the following mandatory key-value pairs as arguments:
160		173
161	"fh" the Perl file handle (not file descriptor) to watch for events	174	"fh" is the Perl file handle (or a naked file descriptor) to watch for
162	(AnyEvent might or might not keep a reference to this file handle).	175	events (AnyEvent might or might not keep a reference to this file
		176	handle). Note that only file handles pointing to things for which
		177	non-blocking operation makes sense are allowed. This includes sockets,
		178	most character devices, pipes, fifos and so on, but not for example
		179	files or block devices.
		180
163	"poll" must be a string that is either "r" or "w", which creates a	181	"poll" must be a string that is either "r" or "w", which creates a
164	watcher waiting for "r"eadable or "w"ritable events, respectively. "cb"	182	watcher waiting for "r"eadable or "w"ritable events, respectively.
		183
165	is the callback to invoke each time the file handle becomes ready.	184	"cb" is the callback to invoke each time the file handle becomes ready.
166		185
167	Although the callback might get passed parameters, their value and	186	Although the callback might get passed parameters, their value and
168	presence is undefined and you cannot rely on them. Portable AnyEvent	187	presence is undefined and you cannot rely on them. Portable AnyEvent
169	callbacks cannot use arguments passed to I/O watcher callbacks.	188	callbacks cannot use arguments passed to I/O watcher callbacks.
170		189
…		…
302	In either case, if you care (and in most cases, you don't), then you	321	In either case, if you care (and in most cases, you don't), then you
303	can get whatever behaviour you want with any event loop, by taking	322	can get whatever behaviour you want with any event loop, by taking
304	the difference between "AnyEvent->time" and "AnyEvent->now" into	323	the difference between "AnyEvent->time" and "AnyEvent->now" into
305	account.	324	account.
306		325
		326	AnyEvent->now_update
		327	Some event loops (such as EV or AnyEvent::Impl::Perl) cache the
		328	current time for each loop iteration (see the discussion of
		329	AnyEvent->now, above).
		330
		331	When a callback runs for a long time (or when the process sleeps),
		332	then this "current" time will differ substantially from the real
		333	time, which might affect timers and time-outs.
		334
		335	When this is the case, you can call this method, which will update
		336	the event loop's idea of "current time".
		337
		338	Note that updating the time might cause some events to be handled.
		339
307	SIGNAL WATCHERS	340	SIGNAL WATCHERS
308	You can watch for signals using a signal watcher, "signal" is the signal	341	You can watch for signals using a signal watcher, "signal" is the signal
309	name in uppercase and without any "SIG" prefix, "cb" is the Perl	342	name in uppercase and without any "SIG" prefix, "cb" is the Perl
310	callback to be invoked whenever a signal occurs.	343	callback to be invoked whenever a signal occurs.
311		344
…		…
317	invocation, and callback invocation will be synchronous. Synchronous	350	invocation, and callback invocation will be synchronous. Synchronous
318	means that it might take a while until the signal gets handled by the	351	means that it might take a while until the signal gets handled by the
319	process, but it is guaranteed not to interrupt any other callbacks.	352	process, but it is guaranteed not to interrupt any other callbacks.
320		353
321	The main advantage of using these watchers is that you can share a	354	The main advantage of using these watchers is that you can share a
322	signal between multiple watchers.	355	signal between multiple watchers, and AnyEvent will ensure that signals
		356	will not interrupt your program at bad times.
323		357
324	This watcher might use %SIG, so programs overwriting those signals	358	This watcher might use %SIG (depending on the event loop used), so
325	directly will likely not work correctly.	359	programs overwriting those signals directly will likely not work
		360	correctly.
		361
		362	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not
		363	support attaching callbacks to signals, which is a pity, as you cannot
		364	do race-free signal handling in perl. AnyEvent will try to do it's best,
		365	but in some cases, signals will be delayed. The maximum time a signal
		366	might be delayed is specified in $AnyEvent::MAX_SIGNAL_LATENCY (default:
		367	10 seconds). This variable can be changed only before the first signal
		368	watcher is created, and should be left alone otherwise. Higher values
		369	will cause fewer spurious wake-ups, which is better for power and CPU
		370	saving. All these problems can be avoided by installing the optional
		371	Async::Interrupt module.
326		372
327	Example: exit on SIGINT	373	Example: exit on SIGINT
328		374
329	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	375	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
330		376
…		…
347		393
348	There is a slight catch to child watchers, however: you usually start	394	There is a slight catch to child watchers, however: you usually start
349	them after the child process was created, and this means the process	395	them after the child process was created, and this means the process
350	could have exited already (and no SIGCHLD will be sent anymore).	396	could have exited already (and no SIGCHLD will be sent anymore).
351		397
352	Not all event models handle this correctly (POE doesn't), but even for	398	Not all event models handle this correctly (neither POE nor IO::Async
		399	do, see their AnyEvent::Impl manpages for details), but even for event
353	event models that do handle this correctly, they usually need to be	400	models that do handle this correctly, they usually need to be loaded
354	loaded before the process exits (i.e. before you fork in the first	401	before the process exits (i.e. before you fork in the first place).
355	place).	402	AnyEvent's pure perl event loop handles all cases correctly regardless
		403	of when you start the watcher.
356		404
357	This means you cannot create a child watcher as the very first thing in	405	This means you cannot create a child watcher as the very first thing in
358	an AnyEvent program, you have to create at least one watcher before	406	an AnyEvent program, you have to create at least one watcher before
359	you "fork" the child (alternatively, you can call "AnyEvent::detect").	407	you "fork" the child (alternatively, you can call "AnyEvent::detect").
360		408
		409	As most event loops do not support waiting for child events, they will
		410	be emulated by AnyEvent in most cases, in which the latency and race
		411	problems mentioned in the description of signal watchers apply.
		412
361	Example: fork a process and wait for it	413	Example: fork a process and wait for it
362		414
363	my $done = AnyEvent->condvar;	415	my $done = AnyEvent->condvar;
364		416
365	my $pid = fork or exit 5;	417	my $pid = fork or exit 5;
366		418
367	my $w = AnyEvent->child (	419	my $w = AnyEvent->child (
368	pid => $pid,	420	pid => $pid,
369	cb => sub {	421	cb => sub {
370	my ($pid, $status) = @_;	422	my ($pid, $status) = @_;
371	warn "pid $pid exited with status $status";	423	warn "pid $pid exited with status $status";
372	$done->send;	424	$done->send;
373	},	425	},
374	);	426	);
375		427
376	# do something else, then wait for process exit	428	# do something else, then wait for process exit
377	$done->recv;	429	$done->recv;
		430
		431	IDLE WATCHERS
		432	Sometimes there is a need to do something, but it is not so important to
		433	do it instantly, but only when there is nothing better to do. This
		434	"nothing better to do" is usually defined to be "no other events need
		435	attention by the event loop".
		436
		437	Idle watchers ideally get invoked when the event loop has nothing better
		438	to do, just before it would block the process to wait for new events.
		439	Instead of blocking, the idle watcher is invoked.
		440
		441	Most event loops unfortunately do not really support idle watchers (only
		442	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		443	will simply call the callback "from time to time".
		444
		445	Example: read lines from STDIN, but only process them when the program
		446	is otherwise idle:
		447
		448	my @lines; # read data
		449	my $idle_w;
		450	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		451	push @lines, scalar <STDIN>;
		452
		453	# start an idle watcher, if not already done
		454	$idle_w \|\|= AnyEvent->idle (cb => sub {
		455	# handle only one line, when there are lines left
		456	if (my $line = shift @lines) {
		457	print "handled when idle: $line";
		458	} else {
		459	# otherwise disable the idle watcher again
		460	undef $idle_w;
		461	}
		462	});
		463	});
378		464
379	CONDITION VARIABLES	465	CONDITION VARIABLES
380	If you are familiar with some event loops you will know that all of them	466	If you are familiar with some event loops you will know that all of them
381	require you to run some blocking "loop", "run" or similar function that	467	require you to run some blocking "loop", "run" or similar function that
382	will actively watch for new events and call your callbacks.	468	will actively watch for new events and call your callbacks.
383		469
384	AnyEvent is different, it expects somebody else to run the event loop	470	AnyEvent is slightly different: it expects somebody else to run the
385	and will only block when necessary (usually when told by the user).	471	event loop and will only block when necessary (usually when told by the
		472	user).
386		473
387	The instrument to do that is called a "condition variable", so called	474	The instrument to do that is called a "condition variable", so called
388	because they represent a condition that must become true.	475	because they represent a condition that must become true.
389		476
		477	Now is probably a good time to look at the examples further below.
		478
390	Condition variables can be created by calling the "AnyEvent->condvar"	479	Condition variables can be created by calling the "AnyEvent->condvar"
391	method, usually without arguments. The only argument pair allowed is	480	method, usually without arguments. The only argument pair allowed is
392
393	"cb", which specifies a callback to be called when the condition	481	"cb", which specifies a callback to be called when the condition
394	variable becomes true, with the condition variable as the first argument	482	variable becomes true, with the condition variable as the first argument
395	(but not the results).	483	(but not the results).
396		484
397	After creation, the condition variable is "false" until it becomes	485	After creation, the condition variable is "false" until it becomes
…		…
446	after => 1,	534	after => 1,
447	cb => sub { $result_ready->send },	535	cb => sub { $result_ready->send },
448	);	536	);
449		537
450	# this "blocks" (while handling events) till the callback	538	# this "blocks" (while handling events) till the callback
451	# calls send	539	# calls -<send
452	$result_ready->recv;	540	$result_ready->recv;
453		541
454	Example: wait for a timer, but take advantage of the fact that condition	542	Example: wait for a timer, but take advantage of the fact that condition
455	variables are also code references.	543	variables are also callable directly.
456		544
457	my $done = AnyEvent->condvar;	545	my $done = AnyEvent->condvar;
458	my $delay = AnyEvent->timer (after => 5, cb => $done);	546	my $delay = AnyEvent->timer (after => 5, cb => $done);
459	$done->recv;	547	$done->recv;
460		548
…		…
466		554
467	...	555	...
468		556
469	my @info = $couchdb->info->recv;	557	my @info = $couchdb->info->recv;
470		558
471	And this is how you would just ste a callback to be called whenever the	559	And this is how you would just set a callback to be called whenever the
472	results are available:	560	results are available:
473		561
474	$couchdb->info->cb (sub {	562	$couchdb->info->cb (sub {
475	my @info = $_[0]->recv;	563	my @info = $_[0]->recv;
476	});	564	});
…		…
491		579
492	Any arguments passed to the "send" call will be returned by all	580	Any arguments passed to the "send" call will be returned by all
493	future "->recv" calls.	581	future "->recv" calls.
494		582
495	Condition variables are overloaded so one can call them directly (as	583	Condition variables are overloaded so one can call them directly (as
496	a code reference). Calling them directly is the same as calling	584	if they were a code reference). Calling them directly is the same as
497	"send". Note, however, that many C-based event loops do not handle	585	calling "send".
498	overloading, so as tempting as it may be, passing a condition
499	variable instead of a callback does not work. Both the pure perl and
500	EV loops support overloading, however, as well as all functions that
501	use perl to invoke a callback (as in AnyEvent::Socket and
502	AnyEvent::DNS for example).
503		586
504	$cv->croak ($error)	587	$cv->croak ($error)
505	Similar to send, but causes all call's to "->recv" to invoke	588	Similar to send, but causes all call's to "->recv" to invoke
506	"Carp::croak" with the given error message/object/scalar.	589	"Carp::croak" with the given error message/object/scalar.
507		590
508	This can be used to signal any errors to the condition variable	591	This can be used to signal any errors to the condition variable
509	user/consumer.	592	user/consumer. Doing it this way instead of calling "croak" directly
		593	delays the error detetcion, but has the overwhelmign advantage that
		594	it diagnoses the error at the place where the result is expected,
		595	and not deep in some event clalback without connection to the actual
		596	code causing the problem.
510		597
511	$cv->begin ([group callback])	598	$cv->begin ([group callback])
512	$cv->end	599	$cv->end
513	These two methods are EXPERIMENTAL and MIGHT CHANGE.
514
515	These two methods can be used to combine many transactions/events	600	These two methods can be used to combine many transactions/events
516	into one. For example, a function that pings many hosts in parallel	601	into one. For example, a function that pings many hosts in parallel
517	might want to use a condition variable for the whole process.	602	might want to use a condition variable for the whole process.
518		603
519	Every call to "->begin" will increment a counter, and every call to	604	Every call to "->begin" will increment a counter, and every call to
520	"->end" will decrement it. If the counter reaches 0 in "->end", the	605	"->end" will decrement it. If the counter reaches 0 in "->end", the
521	(last) callback passed to "begin" will be executed. That callback is	606	(last) callback passed to "begin" will be executed. That callback is
522	supposed to call "->send", but that is not required. If no	607	supposed to call "->send", but that is not required. If no
523	callback was set, "send" will be called without any arguments.	608	callback was set, "send" will be called without any arguments.
524		609
525	Let's clarify this with the ping example:	610	You can think of "$cv->send" giving you an OR condition (one call
		611	sends), while "$cv->begin" and "$cv->end" giving you an AND
		612	condition (all "begin" calls must be "end"'ed before the condvar
		613	sends).
		614
		615	Let's start with a simple example: you have two I/O watchers (for
		616	example, STDOUT and STDERR for a program), and you want to wait for
		617	both streams to close before activating a condvar:
		618
		619	my $cv = AnyEvent->condvar;
		620
		621	$cv->begin; # first watcher
		622	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		623	defined sysread $fh1, my $buf, 4096
		624	or $cv->end;
		625	});
		626
		627	$cv->begin; # second watcher
		628	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		629	defined sysread $fh2, my $buf, 4096
		630	or $cv->end;
		631	});
		632
		633	$cv->recv;
		634
		635	This works because for every event source (EOF on file handle),
		636	there is one call to "begin", so the condvar waits for all calls to
		637	"end" before sending.
		638
		639	The ping example mentioned above is slightly more complicated, as
		640	the there are results to be passwd back, and the number of tasks
		641	that are begung can potentially be zero:
526		642
527	my $cv = AnyEvent->condvar;	643	my $cv = AnyEvent->condvar;
528		644
529	my %result;	645	my %result;
530	$cv->begin (sub { $cv->send (\%result) });	646	$cv->begin (sub { $cv->send (\%result) });
…		…
550	the loop, which serves two important purposes: first, it sets the	666	the loop, which serves two important purposes: first, it sets the
551	callback to be called once the counter reaches 0, and second, it	667	callback to be called once the counter reaches 0, and second, it
552	ensures that "send" is called even when "no" hosts are being pinged	668	ensures that "send" is called even when "no" hosts are being pinged
553	(the loop doesn't execute once).	669	(the loop doesn't execute once).
554		670
555	This is the general pattern when you "fan out" into multiple	671	This is the general pattern when you "fan out" into multiple (but
556	subrequests: use an outer "begin"/"end" pair to set the callback and	672	potentially none) subrequests: use an outer "begin"/"end" pair to
557	ensure "end" is called at least once, and then, for each subrequest	673	set the callback and ensure "end" is called at least once, and then,
558	you start, call "begin" and for each subrequest you finish, call	674	for each subrequest you start, call "begin" and for each subrequest
559	"end".	675	you finish, call "end".
560		676
561	METHODS FOR CONSUMERS	677	METHODS FOR CONSUMERS
562	These methods should only be used by the consuming side, i.e. the code	678	These methods should only be used by the consuming side, i.e. the code
563	awaits the condition.	679	awaits the condition.
564		680
…		…
573	function will call "croak".	689	function will call "croak".
574		690
575	In list context, all parameters passed to "send" will be returned,	691	In list context, all parameters passed to "send" will be returned,
576	in scalar context only the first one will be returned.	692	in scalar context only the first one will be returned.
577		693
		694	Note that doing a blocking wait in a callback is not supported by
		695	any event loop, that is, recursive invocation of a blocking "->recv"
		696	is not allowed, and the "recv" call will "croak" if such a condition
		697	is detected. This condition can be slightly loosened by using
		698	Coro::AnyEvent, which allows you to do a blocking "->recv" from any
		699	thread that doesn't run the event loop itself.
		700
578	Not all event models support a blocking wait - some die in that case	701	Not all event models support a blocking wait - some die in that case
579	(programs might want to do that to stay interactive), so *if you are	702	(programs might want to do that to stay interactive), so *if you are
580	using this from a module, never require a blocking wait*, but let	703	using this from a module, never require a blocking wait*. Instead,
581	the caller decide whether the call will block or not (for example,	704	let the caller decide whether the call will block or not (for
582	by coupling condition variables with some kind of request results	705	example, by coupling condition variables with some kind of request
583	and supporting callbacks so the caller knows that getting the result	706	results and supporting callbacks so the caller knows that getting
584	will not block, while still supporting blocking waits if the caller	707	the result will not block, while still supporting blocking waits if
585	so desires).	708	the caller so desires).
586
587	Another reason never to "->recv" in a module is that you cannot
588	sensibly have two "->recv"'s in parallel, as that would require
589	multiple interpreters or coroutines/threads, none of which
590	"AnyEvent" can supply.
591
592	The Coro module, however, can and does supply coroutines and, in
593	fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe
594	versions and also integrates coroutines into AnyEvent, making
595	blocking "->recv" calls perfectly safe as long as they are done from
596	another coroutine (one that doesn't run the event loop).
597		709
598	You can ensure that "-recv" never blocks by setting a callback and	710	You can ensure that "-recv" never blocks by setting a callback and
599	only calling "->recv" from within that callback (or at a later	711	only calling "->recv" from within that callback (or at a later
600	time). This will work even when the event loop does not support	712	time). This will work even when the event loop does not support
601	blocking waits otherwise.	713	blocking waits otherwise.
…		…
611	The callback will be called when the condition becomes "true", i.e.	723	The callback will be called when the condition becomes "true", i.e.
612	when "send" or "croak" are called, with the only argument being the	724	when "send" or "croak" are called, with the only argument being the
613	condition variable itself. Calling "recv" inside the callback or at	725	condition variable itself. Calling "recv" inside the callback or at
614	any later time is guaranteed not to block.	726	any later time is guaranteed not to block.
615		727
		728	SUPPORTED EVENT LOOPS/BACKENDS
		729	The available backend classes are (every class has its own manpage):
		730
		731	Backends that are autoprobed when no other event loop can be found.
		732	EV is the preferred backend when no other event loop seems to be in
		733	use. If EV is not installed, then AnyEvent will try Event, and,
		734	failing that, will fall back to its own pure-perl implementation,
		735	which is available everywhere as it comes with AnyEvent itself.
		736
		737	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		738	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		739	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		740
		741	Backends that are transparently being picked up when they are used.
		742	These will be used when they are currently loaded when the first
		743	watcher is created, in which case it is assumed that the application
		744	is using them. This means that AnyEvent will automatically pick the
		745	right backend when the main program loads an event module before
		746	anything starts to create watchers. Nothing special needs to be done
		747	by the main program.
		748
		749	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		750	AnyEvent::Impl::Tk based on Tk, very broken.
		751	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		752	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		753
		754	Backends with special needs.
		755	Qt requires the Qt::Application to be instantiated first, but will
		756	otherwise be picked up automatically. As long as the main program
		757	instantiates the application before any AnyEvent watchers are
		758	created, everything should just work.
		759
		760	AnyEvent::Impl::Qt based on Qt.
		761
		762	Support for IO::Async can only be partial, as it is too broken and
		763	architecturally limited to even support the AnyEvent API. It also is
		764	the only event loop that needs the loop to be set explicitly, so it
		765	can only be used by a main program knowing about AnyEvent. See
		766	AnyEvent::Impl::Async for the gory details.
		767
		768	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		769
		770	Event loops that are indirectly supported via other backends.
		771	Some event loops can be supported via other modules:
		772
		773	There is no direct support for WxWidgets (Wx) or Prima.
		774
		775	WxWidgets has no support for watching file handles. However, you can
		776	use WxWidgets through the POE adaptor, as POE has a Wx backend that
		777	simply polls 20 times per second, which was considered to be too
		778	horrible to even consider for AnyEvent.
		779
		780	Prima is not supported as nobody seems to be using it, but it has a
		781	POE backend, so it can be supported through POE.
		782
		783	AnyEvent knows about both Prima and Wx, however, and will try to
		784	load POE when detecting them, in the hope that POE will pick them
		785	up, in which case everything will be automatic.
		786
616	GLOBAL VARIABLES AND FUNCTIONS	787	GLOBAL VARIABLES AND FUNCTIONS
		788	These are not normally required to use AnyEvent, but can be useful to
		789	write AnyEvent extension modules.
		790
617	$AnyEvent::MODEL	791	$AnyEvent::MODEL
618	Contains "undef" until the first watcher is being created. Then it	792	Contains "undef" until the first watcher is being created, before
		793	the backend has been autodetected.
		794
619	contains the event model that is being used, which is the name of	795	Afterwards it contains the event model that is being used, which is
620	the Perl class implementing the model. This class is usually one of	796	the name of the Perl class implementing the model. This class is
621	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	797	usually one of the "AnyEvent::Impl:xxx" modules, but can be any
622	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	798	other class in the case AnyEvent has been extended at runtime (e.g.
623		799	in rxvt-unicode it will be "urxvt::anyevent").
624	The known classes so far are:
625
626	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
627	AnyEvent::Impl::Event based on Event, second best choice.
628	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
629	AnyEvent::Impl::Glib based on Glib, third-best choice.
630	AnyEvent::Impl::Tk based on Tk, very bad choice.
631	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
632	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
633	AnyEvent::Impl::POE based on POE, not generic enough for full support.
634
635	There is no support for WxWidgets, as WxWidgets has no support for
636	watching file handles. However, you can use WxWidgets through the
637	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
638	second, which was considered to be too horrible to even consider for
639	AnyEvent. Likewise, other POE backends can be used by AnyEvent by
640	using it's adaptor.
641
642	AnyEvent knows about Prima and Wx and will try to use POE when
643	autodetecting them.
644		800
645	AnyEvent::detect	801	AnyEvent::detect
646	Returns $AnyEvent::MODEL, forcing autodetection of the event model	802	Returns $AnyEvent::MODEL, forcing autodetection of the event model
647	if necessary. You should only call this function right before you	803	if necessary. You should only call this function right before you
648	would have created an AnyEvent watcher anyway, that is, as late as	804	would have created an AnyEvent watcher anyway, that is, as late as
649	possible at runtime.	805	possible at runtime, and not e.g. while initialising of your module.
		806
		807	If you need to do some initialisation before AnyEvent watchers are
		808	created, use "post_detect".
650		809
651	$guard = AnyEvent::post_detect { BLOCK }	810	$guard = AnyEvent::post_detect { BLOCK }
652	Arranges for the code block to be executed as soon as the event	811	Arranges for the code block to be executed as soon as the event
653	model is autodetected (or immediately if this has already happened).	812	model is autodetected (or immediately if this has already happened).
		813
		814	The block will be executed after the actual backend has been
		815	detected ($AnyEvent::MODEL is set), but before any watchers have
		816	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
		817	other initialisations - see the sources of AnyEvent::Strict or
		818	AnyEvent::AIO to see how this is used.
		819
		820	The most common usage is to create some global watchers, without
		821	forcing event module detection too early, for example, AnyEvent::AIO
		822	creates and installs the global IO::AIO watcher in a "post_detect"
		823	block to avoid autodetecting the event module at load time.
654		824
655	If called in scalar or list context, then it creates and returns an	825	If called in scalar or list context, then it creates and returns an
656	object that automatically removes the callback again when it is	826	object that automatically removes the callback again when it is
657	destroyed. See Coro::BDB for a case where this is useful.	827	destroyed. See Coro::BDB for a case where this is useful.
658		828
…		…
660	If there are any code references in this array (you can "push" to it	830	If there are any code references in this array (you can "push" to it
661	before or after loading AnyEvent), then they will called directly	831	before or after loading AnyEvent), then they will called directly
662	after the event loop has been chosen.	832	after the event loop has been chosen.
663		833
664	You should check $AnyEvent::MODEL before adding to this array,	834	You should check $AnyEvent::MODEL before adding to this array,
665	though: if it contains a true value then the event loop has already	835	though: if it is defined then the event loop has already been
666	been detected, and the array will be ignored.	836	detected, and the array will be ignored.
667		837
668	Best use "AnyEvent::post_detect { BLOCK }" instead.	838	Best use "AnyEvent::post_detect { BLOCK }" when your application
		839	allows it,as it takes care of these details.
		840
		841	This variable is mainly useful for modules that can do something
		842	useful when AnyEvent is used and thus want to know when it is
		843	initialised, but do not need to even load it by default. This array
		844	provides the means to hook into AnyEvent passively, without loading
		845	it.
669		846
670	WHAT TO DO IN A MODULE	847	WHAT TO DO IN A MODULE
671	As a module author, you should "use AnyEvent" and call AnyEvent methods	848	As a module author, you should "use AnyEvent" and call AnyEvent methods
672	freely, but you should not load a specific event module or rely on it.	849	freely, but you should not load a specific event module or rely on it.
673		850
…		…
724	variable somewhere, waiting for it, and sending it when the program	901	variable somewhere, waiting for it, and sending it when the program
725	should exit cleanly.	902	should exit cleanly.
726		903
727	OTHER MODULES	904	OTHER MODULES
728	The following is a non-exhaustive list of additional modules that use	905	The following is a non-exhaustive list of additional modules that use
729	AnyEvent and can therefore be mixed easily with other AnyEvent modules	906	AnyEvent as a client and can therefore be mixed easily with other
730	in the same program. Some of the modules come with AnyEvent, some are	907	AnyEvent modules and other event loops in the same program. Some of the
731	available via CPAN.	908	modules come with AnyEvent, most are available via CPAN.
732		909
733	AnyEvent::Util	910	AnyEvent::Util
734	Contains various utility functions that replace often-used but	911	Contains various utility functions that replace often-used but
735	blocking functions such as "inet_aton" by event-/callback-based	912	blocking functions such as "inet_aton" by event-/callback-based
736	versions.	913	versions.
…		…
742	more.	919	more.
743		920
744	AnyEvent::Handle	921	AnyEvent::Handle
745	Provide read and write buffers, manages watchers for reads and	922	Provide read and write buffers, manages watchers for reads and
746	writes, supports raw and formatted I/O, I/O queued and fully	923	writes, supports raw and formatted I/O, I/O queued and fully
747	transparent and non-blocking SSL/TLS.	924	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
748		925
749	AnyEvent::DNS	926	AnyEvent::DNS
750	Provides rich asynchronous DNS resolver capabilities.	927	Provides rich asynchronous DNS resolver capabilities.
751		928
752	AnyEvent::HTTP	929	AnyEvent::HTTP
…		…
773		950
774	AnyEvent::GPSD	951	AnyEvent::GPSD
775	A non-blocking interface to gpsd, a daemon delivering GPS	952	A non-blocking interface to gpsd, a daemon delivering GPS
776	information.	953	information.
777		954
		955	AnyEvent::IRC
		956	AnyEvent based IRC client module family (replacing the older
		957	Net::IRC3).
		958
		959	AnyEvent::XMPP
		960	AnyEvent based XMPP (Jabber protocol) module family (replacing the
		961	older Net::XMPP2>.
		962
778	AnyEvent::IGS	963	AnyEvent::IGS
779	A non-blocking interface to the Internet Go Server protocol (used by	964	A non-blocking interface to the Internet Go Server protocol (used by
780	App::IGS).	965	App::IGS).
781		966
782	AnyEvent::IRC
783	AnyEvent based IRC client module family (replacing the older
784	Net::IRC3).
785
786	Net::XMPP2
787	AnyEvent based XMPP (Jabber protocol) module family.
788
789	Net::FCP	967	Net::FCP
790	AnyEvent-based implementation of the Freenet Client Protocol,	968	AnyEvent-based implementation of the Freenet Client Protocol,
791	birthplace of AnyEvent.	969	birthplace of AnyEvent.
792		970
793	Event::ExecFlow	971	Event::ExecFlow
794	High level API for event-based execution flow control.	972	High level API for event-based execution flow control.
795		973
796	Coro	974	Coro
797	Has special support for AnyEvent via Coro::AnyEvent.	975	Has special support for AnyEvent via Coro::AnyEvent.
798
799	IO::Lambda
800	The lambda approach to I/O - don't ask, look there. Can use
801	AnyEvent.
802		976
803	ERROR AND EXCEPTION HANDLING	977	ERROR AND EXCEPTION HANDLING
804	In general, AnyEvent does not do any error handling - it relies on the	978	In general, AnyEvent does not do any error handling - it relies on the
805	caller to do that if required. The AnyEvent::Strict module (see also the	979	caller to do that if required. The AnyEvent::Strict module (see also the
806	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict	980	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
…		…
816	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",	990	"condvar->recv"), the Event and EV modules call "$Event/EV::DIED->()",
817	Glib uses "install_exception_handler" and so on.	991	Glib uses "install_exception_handler" and so on.
818		992
819	ENVIRONMENT VARIABLES	993	ENVIRONMENT VARIABLES
820	The following environment variables are used by this module or its	994	The following environment variables are used by this module or its
821	submodules:	995	submodules.
		996
		997	Note that AnyEvent will remove all environment variables starting with
		998	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		999	enabled.
822		1000
823	"PERL_ANYEVENT_VERBOSE"	1001	"PERL_ANYEVENT_VERBOSE"
824	By default, AnyEvent will be completely silent except in fatal	1002	By default, AnyEvent will be completely silent except in fatal
825	conditions. You can set this environment variable to make AnyEvent	1003	conditions. You can set this environment variable to make AnyEvent
826	more talkative.	1004	more talkative.
…		…
829	conditions, such as not being able to load the event model specified	1007	conditions, such as not being able to load the event model specified
830	by "PERL_ANYEVENT_MODEL".	1008	by "PERL_ANYEVENT_MODEL".
831		1009
832	When set to 2 or higher, cause AnyEvent to report to STDERR which	1010	When set to 2 or higher, cause AnyEvent to report to STDERR which
833	event model it chooses.	1011	event model it chooses.
		1012
		1013	When set to 8 or higher, then AnyEvent will report extra information
		1014	on which optional modules it loads and how it implements certain
		1015	features.
834		1016
835	"PERL_ANYEVENT_STRICT"	1017	"PERL_ANYEVENT_STRICT"
836	AnyEvent does not do much argument checking by default, as thorough	1018	AnyEvent does not do much argument checking by default, as thorough
837	argument checking is very costly. Setting this variable to a true	1019	argument checking is very costly. Setting this variable to a true
838	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1020	value will cause AnyEvent to load "AnyEvent::Strict" and then to
839	thoroughly check the arguments passed to most method calls. If it	1021	thoroughly check the arguments passed to most method calls. If it
840	finds any problems it will croak.	1022	finds any problems, it will croak.
841		1023
842	In other words, enables "strict" mode.	1024	In other words, enables "strict" mode.
843		1025
844	Unlike "use strict", it is definitely recommended ot keep it off in	1026	Unlike "use strict" (or it's modern cousin, "use common::sense", it
845	production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment	1027	is definitely recommended to keep it off in production. Keeping
		1028	"PERL_ANYEVENT_STRICT=1" in your environment while developing
846	while developing programs can be very useful, however.	1029	programs can be very useful, however.
847		1030
848	"PERL_ANYEVENT_MODEL"	1031	"PERL_ANYEVENT_MODEL"
849	This can be used to specify the event model to be used by AnyEvent,	1032	This can be used to specify the event model to be used by AnyEvent,
850	before auto detection and -probing kicks in. It must be a string	1033	before auto detection and -probing kicks in. It must be a string
851	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1034	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
…		…
870	mentioned will be used, and preference will be given to protocols	1053	mentioned will be used, and preference will be given to protocols
871	mentioned earlier in the list.	1054	mentioned earlier in the list.
872		1055
873	This variable can effectively be used for denial-of-service attacks	1056	This variable can effectively be used for denial-of-service attacks
874	against local programs (e.g. when setuid), although the impact is	1057	against local programs (e.g. when setuid), although the impact is
875	likely small, as the program has to handle connection errors	1058	likely small, as the program has to handle conenction and other
876	already-	1059	failures anyways.
877		1060
878	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over	1061	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over
879	IPv6, but support both and try to use both.	1062	IPv6, but support both and try to use both.
880	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to	1063	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
881	resolve or contact IPv6 addresses.	1064	resolve or contact IPv6 addresses.
…		…
892	EDNS0 in its DNS requests.	1075	EDNS0 in its DNS requests.
893		1076
894	"PERL_ANYEVENT_MAX_FORKS"	1077	"PERL_ANYEVENT_MAX_FORKS"
895	The maximum number of child processes that	1078	The maximum number of child processes that
896	"AnyEvent::Util::fork_call" will create in parallel.	1079	"AnyEvent::Util::fork_call" will create in parallel.
		1080
		1081	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
		1082	The default value for the "max_outstanding" parameter for the
		1083	default DNS resolver - this is the maximum number of parallel DNS
		1084	requests that are sent to the DNS server.
		1085
		1086	"PERL_ANYEVENT_RESOLV_CONF"
		1087	The file to use instead of /etc/resolv.conf (or OS-specific
		1088	configuration) in the default resolver. When set to the empty
		1089	string, no default config will be used.
		1090
		1091	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
		1092	When neither "ca_file" nor "ca_path" was specified during
		1093	AnyEvent::TLS context creation, and either of these environment
		1094	variables exist, they will be used to specify CA certificate
		1095	locations instead of a system-dependent default.
		1096
		1097	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
		1098	When these are set to 1, then the respective modules are not loaded.
		1099	Mostly good for testing AnyEvent itself.
897		1100
898	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1101	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
899	This is an advanced topic that you do not normally need to use AnyEvent	1102	This is an advanced topic that you do not normally need to use AnyEvent
900	in a module. This section is only of use to event loop authors who want	1103	in a module. This section is only of use to event loop authors who want
901	to provide AnyEvent compatibility.	1104	to provide AnyEvent compatibility.
…		…
1134	Results	1337	Results
1135	name watchers bytes create invoke destroy comment	1338	name watchers bytes create invoke destroy comment
1136	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	1339	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1137	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1340	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1138	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1341	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1139	Perl/Any 100000 452 4.14 0.75 0.99 pure perl implementation	1342	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1140	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1343	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1141	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1344	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1345	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1346	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1142	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1347	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1143	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1348	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1144	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1349	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1145	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1350	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1146		1351
…		…
1175	few of them active), of course, but this was not subject of this	1380	few of them active), of course, but this was not subject of this
1176	benchmark.	1381	benchmark.
1177		1382
1178	The "Event" module has a relatively high setup and callback invocation	1383	The "Event" module has a relatively high setup and callback invocation
1179	cost, but overall scores in on the third place.	1384	cost, but overall scores in on the third place.
		1385
		1386	"IO::Async" performs admirably well, about on par with "Event", even
		1387	when using its pure perl backend.
1180		1388
1181	"Glib"'s memory usage is quite a bit higher, but it features a faster	1389	"Glib"'s memory usage is quite a bit higher, but it features a faster
1182	callback invocation and overall ends up in the same class as "Event".	1390	callback invocation and overall ends up in the same class as "Event".
1183	However, Glib scales extremely badly, doubling the number of watchers	1391	However, Glib scales extremely badly, doubling the number of watchers
1184	increases the processing time by more than a factor of four, making it	1392	increases the processing time by more than a factor of four, making it
…		…
1255	single "request", that is, reading the token from the pipe and	1463	single "request", that is, reading the token from the pipe and
1256	forwarding it to another server. This includes deleting the old timeout	1464	forwarding it to another server. This includes deleting the old timeout
1257	and creating a new one that moves the timeout into the future.	1465	and creating a new one that moves the timeout into the future.
1258		1466
1259	Results	1467	Results
1260	name sockets create request	1468	name sockets create request
1261	EV 20000 69.01 11.16	1469	EV 20000 69.01 11.16
1262	Perl 20000 73.32 35.87	1470	Perl 20000 73.32 35.87
		1471	IOAsync 20000 157.00 98.14 epoll
		1472	IOAsync 20000 159.31 616.06 poll
1263	Event 20000 212.62 257.32	1473	Event 20000 212.62 257.32
1264	Glib 20000 651.16 1896.30	1474	Glib 20000 651.16 1896.30
1265	POE 20000 349.67 12317.24 uses POE::Loop::Event	1475	POE 20000 349.67 12317.24 uses POE::Loop::Event
1266		1476
1267	Discussion	1477	Discussion
1268	This benchmark does measure scalability and overall performance of the	1478	This benchmark does measure scalability and overall performance of the
1269	particular event loop.	1479	particular event loop.
1270		1480
1271	EV is again fastest. Since it is using epoll on my system, the setup	1481	EV is again fastest. Since it is using epoll on my system, the setup
1272	time is relatively high, though.	1482	time is relatively high, though.
1273		1483
1274	Perl surprisingly comes second. It is much faster than the C-based event	1484	Perl surprisingly comes second. It is much faster than the C-based event
1275	loops Event and Glib.	1485	loops Event and Glib.
		1486
		1487	IO::Async performs very well when using its epoll backend, and still
		1488	quite good compared to Glib when using its pure perl backend.
1276		1489
1277	Event suffers from high setup time as well (look at its code and you	1490	Event suffers from high setup time as well (look at its code and you
1278	will understand why). Callback invocation also has a high overhead	1491	will understand why). Callback invocation also has a high overhead
1279	compared to the "$_->() for .."-style loop that the Perl event loop	1492	compared to the "$_->() for .."-style loop that the Perl event loop
1280	uses. Event uses select or poll in basically all documented	1493	uses. Event uses select or poll in basically all documented
…		…
1331		1544
1332	Summary	1545	Summary
1333	* C-based event loops perform very well with small number of watchers,	1546	* C-based event loops perform very well with small number of watchers,
1334	as the management overhead dominates.	1547	as the management overhead dominates.
1335		1548
		1549	THE IO::Lambda BENCHMARK
		1550	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1551	could be misinterpreted to make AnyEvent look bad. In fact, the
		1552	benchmark simply compares IO::Lambda with POE, and IO::Lambda looks
		1553	better (which shouldn't come as a surprise to anybody). As such, the
		1554	benchmark is fine, and mostly shows that the AnyEvent backend from
		1555	IO::Lambda isn't very optimal. But how would AnyEvent compare when used
		1556	without the extra baggage? To explore this, I wrote the equivalent
		1557	benchmark for AnyEvent.
		1558
		1559	The benchmark itself creates an echo-server, and then, for 500 times,
		1560	connects to the echo server, sends a line, waits for the reply, and then
		1561	creates the next connection. This is a rather bad benchmark, as it
		1562	doesn't test the efficiency of the framework or much non-blocking I/O,
		1563	but it is a benchmark nevertheless.
		1564
		1565	name runtime
		1566	Lambda/select 0.330 sec
		1567	+ optimized 0.122 sec
		1568	Lambda/AnyEvent 0.327 sec
		1569	+ optimized 0.138 sec
		1570	Raw sockets/select 0.077 sec
		1571	POE/select, components 0.662 sec
		1572	POE/select, raw sockets 0.226 sec
		1573	POE/select, optimized 0.404 sec
		1574
		1575	AnyEvent/select/nb 0.085 sec
		1576	AnyEvent/EV/nb 0.068 sec
		1577	+state machine 0.134 sec
		1578
		1579	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1580	benchmarks actually make blocking connects and use 100% blocking I/O,
		1581	defeating the purpose of an event-based solution. All of the newly
		1582	written AnyEvent benchmarks use 100% non-blocking connects (using
		1583	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1584	resolver), so AnyEvent is at a disadvantage here, as non-blocking
		1585	connects generally require a lot more bookkeeping and event handling
		1586	than blocking connects (which involve a single syscall only).
		1587
		1588	The last AnyEvent benchmark additionally uses AnyEvent::Handle, which
		1589	offers similar expressive power as POE and IO::Lambda, using
		1590	conventional Perl syntax. This means that both the echo server and the
		1591	client are 100% non-blocking, further placing it at a disadvantage.
		1592
		1593	As you can see, the AnyEvent + EV combination even beats the
		1594	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1595	backend easily beats IO::Lambda and POE.
		1596
		1597	And even the 100% non-blocking version written using the high-level (and
		1598	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda by a
		1599	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1600	in a non-blocking way.
		1601
		1602	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
		1603	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
		1604	part of the IO::lambda distribution and were used without any changes.
		1605
1336	SIGNALS	1606	SIGNALS
1337	AnyEvent currently installs handlers for these signals:	1607	AnyEvent currently installs handlers for these signals:
1338		1608
1339	SIGCHLD	1609	SIGCHLD
1340	A handler for "SIGCHLD" is installed by AnyEvent's child watcher	1610	A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1341	emulation for event loops that do not support them natively. Also,	1611	emulation for event loops that do not support them natively. Also,
1342	some event loops install a similar handler.	1612	some event loops install a similar handler.
		1613
		1614	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE,
		1615	then AnyEvent will reset it to default, to avoid losing child exit
		1616	statuses.
1343		1617
1344	SIGPIPE	1618	SIGPIPE
1345	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is	1619	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1346	"undef" when AnyEvent gets loaded.	1620	"undef" when AnyEvent gets loaded.
1347		1621
…		…
1355	it is that this way, the handler will be restored to defaults on	1629	it is that this way, the handler will be restored to defaults on
1356	exec.	1630	exec.
1357		1631
1358	Feel free to install your own handler, or reset it to defaults.	1632	Feel free to install your own handler, or reset it to defaults.
1359		1633
		1634	RECOMMENDED/OPTIONAL MODULES
		1635	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		1636	it's built-in modules) are required to use it.
		1637
		1638	That does not mean that AnyEvent won't take advantage of some additional
		1639	modules if they are installed.
		1640
		1641	This section epxlains which additional modules will be used, and how
		1642	they affect AnyEvent's operetion.
		1643
		1644	Async::Interrupt
		1645	This slightly arcane module is used to implement fast signal
		1646	handling: To my knowledge, there is no way to do completely
		1647	race-free and quick signal handling in pure perl. To ensure that
		1648	signals still get delivered, AnyEvent will start an interval timer
		1649	to wake up perl (and catch the signals) with soemd elay (default is
		1650	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
		1651
		1652	If this module is available, then it will be used to implement
		1653	signal catching, which means that signals will not be delayed, and
		1654	the event loop will not be interrupted regularly, which is more
		1655	efficient (And good for battery life on laptops).
		1656
		1657	This affects not just the pure-perl event loop, but also other event
		1658	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
		1659
		1660	EV This module isn't really "optional", as it is simply one of the
		1661	backend event loops that AnyEvent can use. However, it is simply the
		1662	best event loop available in terms of features, speed and stability:
		1663	It supports the AnyEvent API optimally, implements all the watcher
		1664	types in XS, does automatic timer adjustments even when no monotonic
		1665	clock is available, can take avdantage of advanced kernel interfaces
		1666	such as "epoll" and "kqueue", and is the fastest backend by far.
		1667	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
		1668	Glib::EV).
		1669
		1670	Guard
		1671	The guard module, when used, will be used to implement
		1672	"AnyEvent::Util::guard". This speeds up guards considerably (and
		1673	uses a lot less memory), but otherwise doesn't affect guard
		1674	operation much. It is purely used for performance.
		1675
		1676	JSON and JSON::XS
		1677	This module is required when you want to read or write JSON data via
		1678	AnyEvent::Handle. It is also written in pure-perl, but can take
		1679	advantage of the ulta-high-speed JSON::XS module when it is
		1680	installed.
		1681
		1682	In fact, AnyEvent::Handle will use JSON::XS by default if it is
		1683	installed.
		1684
		1685	Net::SSLeay
		1686	Implementing TLS/SSL in Perl is certainly interesting, but not very
		1687	worthwhile: If this module is installed, then AnyEvent::Handle (with
		1688	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
		1689
		1690	Time::HiRes
		1691	This module is part of perl since release 5.008. It will be used
		1692	when the chosen event library does not come with a timing source on
		1693	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will
		1694	additionally use it to try to use a monotonic clock for timing
		1695	stability.
		1696
1360	FORK	1697	FORK
1361	Most event libraries are not fork-safe. The ones who are usually are	1698	Most event libraries are not fork-safe. The ones who are usually are
1362	because they rely on inefficient but fork-safe "select" or "poll" calls.	1699	because they rely on inefficient but fork-safe "select" or "poll" calls.
1363	Only EV is fully fork-aware.	1700	Only EV is fully fork-aware.
1364		1701
1365	If you have to fork, you must either do so before creating your first	1702	If you have to fork, you must either do so before creating your first
1366	watcher OR you must not use AnyEvent at all in the child.	1703	watcher OR you must not use AnyEvent at all in the child OR you must do
		1704	something completely out of the scope of AnyEvent.
1367		1705
1368	SECURITY CONSIDERATIONS	1706	SECURITY CONSIDERATIONS
1369	AnyEvent can be forced to load any event model via	1707	AnyEvent can be forced to load any event model via
1370	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1708	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1371	to execute arbitrary code or directly gain access, it can easily be used	1709	to execute arbitrary code or directly gain access, it can easily be used
…		…
1375		1713
1376	You can make AnyEvent completely ignore this variable by deleting it	1714	You can make AnyEvent completely ignore this variable by deleting it
1377	before the first watcher gets created, e.g. with a "BEGIN" block:	1715	before the first watcher gets created, e.g. with a "BEGIN" block:
1378		1716
1379	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1717	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1380		1718
1381	use AnyEvent;	1719	use AnyEvent;
1382		1720
1383	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1721	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1384	be used to probe what backend is used and gain other information (which	1722	be used to probe what backend is used and gain other information (which
1385	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),	1723	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1386	and $ENV{PERL_ANYEGENT_STRICT}.	1724	and $ENV{PERL_ANYEVENT_STRICT}.
		1725
		1726	Note that AnyEvent will remove all environment variables starting with
		1727	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		1728	enabled.
1387		1729
1388	BUGS	1730	BUGS
1389	Perl 5.8 has numerous memleaks that sometimes hit this module and are	1731	Perl 5.8 has numerous memleaks that sometimes hit this module and are
1390	hard to work around. If you suffer from memleaks, first upgrade to Perl	1732	hard to work around. If you suffer from memleaks, first upgrade to Perl
1391	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1733	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1392	annoying mamleaks, such as leaking on "map" and "grep" but it is usually	1734	annoying memleaks, such as leaking on "map" and "grep" but it is usually
1393	not as pronounced).	1735	not as pronounced).
1394		1736
1395	SEE ALSO	1737	SEE ALSO
1396	Utility functions: AnyEvent::Util.	1738	Utility functions: AnyEvent::Util.
1397		1739
1398	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1740	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1399	Event::Lib, Qt, POE.	1741	Event::Lib, Qt, POE.
1400		1742
1401	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1743	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1402	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1744	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1403	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1745	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		1746	AnyEvent::Impl::IOAsync.
1404		1747
1405	Non-blocking file handles, sockets, TCP clients and servers:	1748	Non-blocking file handles, sockets, TCP clients and servers:
1406	AnyEvent::Handle, AnyEvent::Socket.	1749	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1407		1750
1408	Asynchronous DNS: AnyEvent::DNS.	1751	Asynchronous DNS: AnyEvent::DNS.
1409		1752
1410	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1753	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1411		1754
1412	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.	1755	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
		1756	AnyEvent::HTTP.
1413		1757
1414	AUTHOR	1758	AUTHOR
1415	Marc Lehmann <schmorp@schmorp.de>	1759	Marc Lehmann <schmorp@schmorp.de>
1416	http://home.schmorp.de/	1760	http://home.schmorp.de/
1417		1761

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent/README (file contents): Revision 1.33 by root, Thu Oct 30 03:43:13 2008 UTC vs. Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC

Diff Legend

Comparing AnyEvent/README (file contents):
Revision 1.33 by root, Thu Oct 30 03:43:13 2008 UTC vs.
Revision 1.46 by root, Sat Jul 18 05:19:09 2009 UTC