[ViewVC] Diff of: cvs/AnyEvent/README

Comparing AnyEvent/README (file contents):
Revision 1.40 by root, Tue Jun 23 23:37:32 2009 UTC vs.
Revision 1.62 by root, Sun Jun 6 10:13:57 2010 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	# if you prefer function calls, look at the AE manpage for
		11	# an alternative API.
		12
10	# file descriptor readable	13	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	14	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		15
13	# one-shot or repeating timers	16	# one-shot or repeating timers
14	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	17	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
15	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	18	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
37		40
38	INTRODUCTION/TUTORIAL	41	INTRODUCTION/TUTORIAL
39	This manpage is mainly a reference manual. If you are interested in a	42	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	43	tutorial or some gentle introduction, have a look at the AnyEvent::Intro
41	manpage.	44	manpage.
		45
		46	SUPPORT
		47	There is a mailinglist for discussing all things AnyEvent, and an IRC
		48	channel, too.
		49
		50	See the AnyEvent project page at the Schmorpforge Ta-Sa Software
		51	Repository, at <http://anyevent.schmorp.de>, for more info.
42		52
43	WHY YOU SHOULD USE THIS MODULE (OR NOT)	53	WHY YOU SHOULD USE THIS MODULE (OR NOT)
44	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	54	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
45	nowadays. So what is different about AnyEvent?	55	nowadays. So what is different about AnyEvent?
46		56
…		…
166	Note that "my $w; $w =" combination. This is necessary because in Perl,	176	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	177	my variables are only visible after the statement in which they are
168	declared.	178	declared.
169		179
170	I/O WATCHERS	180	I/O WATCHERS
		181	$w = AnyEvent->io (
		182	fh => <filehandle_or_fileno>,
		183	poll => <"r" or "w">,
		184	cb => <callback>,
		185	);
		186
171	You can create an I/O watcher by calling the "AnyEvent->io" method with	187	You can create an I/O watcher by calling the "AnyEvent->io" method with
172	the following mandatory key-value pairs as arguments:	188	the following mandatory key-value pairs as arguments:
173		189
174	"fh" is the Perl file handle (not file descriptor) to watch for	190	"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	191	events (AnyEvent might or might not keep a reference to this file
176	handle). Note that only file handles pointing to things for which	192	handle). Note that only file handles pointing to things for which
177	non-blocking operation makes sense are allowed. This includes sockets,	193	non-blocking operation makes sense are allowed. This includes sockets,
178	most character devices, pipes, fifos and so on, but not for example	194	most character devices, pipes, fifos and so on, but not for example
179	files or block devices.	195	files or block devices.
…		…
203	warn "read: $input\n";	219	warn "read: $input\n";
204	undef $w;	220	undef $w;
205	});	221	});
206		222
207	TIME WATCHERS	223	TIME WATCHERS
		224	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		225
		226	$w = AnyEvent->timer (
		227	after => <fractional_seconds>,
		228	interval => <fractional_seconds>,
		229	cb => <callback>,
		230	);
		231
208	You can create a time watcher by calling the "AnyEvent->timer" method	232	You can create a time watcher by calling the "AnyEvent->timer" method
209	with the following mandatory arguments:	233	with the following mandatory arguments:
210		234
211	"after" specifies after how many seconds (fractional values are	235	"after" specifies after how many seconds (fractional values are
212	supported) the callback should be invoked. "cb" is the callback to	236	supported) the callback should be invoked. "cb" is the callback to
…		…
333	time, which might affect timers and time-outs.	357	time, which might affect timers and time-outs.
334		358
335	When this is the case, you can call this method, which will update	359	When this is the case, you can call this method, which will update
336	the event loop's idea of "current time".	360	the event loop's idea of "current time".
337		361
		362	A typical example would be a script in a web server (e.g.
		363	"mod_perl") - when mod_perl executes the script, then the event loop
		364	will have the wrong idea about the "current time" (being potentially
		365	far in the past, when the script ran the last time). In that case
		366	you should arrange a call to "AnyEvent->now_update" each time the
		367	web server process wakes up again (e.g. at the start of your script,
		368	or in a handler).
		369
338	Note that updating the time might cause some events to be handled.	370	Note that updating the time might cause some events to be handled.
339		371
340	SIGNAL WATCHERS	372	SIGNAL WATCHERS
		373	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		374
341	You can watch for signals using a signal watcher, "signal" is the signal	375	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	376	name in uppercase and without any "SIG" prefix, "cb" is the Perl
343	callback to be invoked whenever a signal occurs.	377	callback to be invoked whenever a signal occurs.
344		378
345	Although the callback might get passed parameters, their value and	379	Although the callback might get passed parameters, their value and
…		…
350	invocation, and callback invocation will be synchronous. Synchronous	384	invocation, and callback invocation will be synchronous. Synchronous
351	means that it might take a while until the signal gets handled by the	385	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.	386	process, but it is guaranteed not to interrupt any other callbacks.
353		387
354	The main advantage of using these watchers is that you can share a	388	The main advantage of using these watchers is that you can share a
355	signal between multiple watchers.	389	signal between multiple watchers, and AnyEvent will ensure that signals
		390	will not interrupt your program at bad times.
356		391
357	This watcher might use %SIG, so programs overwriting those signals	392	This watcher might use %SIG (depending on the event loop used), so
358	directly will likely not work correctly.	393	programs overwriting those signals directly will likely not work
		394	correctly.
359		395
360	Example: exit on SIGINT	396	Example: exit on SIGINT
361		397
362	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	398	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
363		399
		400	Restart Behaviour
		401	While restart behaviour is up to the event loop implementation, most
		402	will not restart syscalls (that includes Async::Interrupt and AnyEvent's
		403	pure perl implementation).
		404
		405	Safe/Unsafe Signals
		406	Perl signals can be either "safe" (synchronous to opcode handling) or
		407	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		408	latter might corrupt your memory.
		409
		410	AnyEvent signal handlers are, in addition, synchronous to the event
		411	loop, i.e. they will not interrupt your running perl program but will
		412	only be called as part of the normal event handling (just like timer,
		413	I/O etc. callbacks, too).
		414
		415	Signal Races, Delays and Workarounds
		416	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		417	callbacks to signals in a generic way, which is a pity, as you cannot do
		418	race-free signal handling in perl, requiring C libraries for this.
		419	AnyEvent will try to do it's best, which means in some cases, signals
		420	will be delayed. The maximum time a signal might be delayed is specified
		421	in $AnyEvent::MAX_SIGNAL_LATENCY (default: 10 seconds). This variable
		422	can be changed only before the first signal watcher is created, and
		423	should be left alone otherwise. This variable determines how often
		424	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		425	will cause fewer spurious wake-ups, which is better for power and CPU
		426	saving.
		427
		428	All these problems can be avoided by installing the optional
		429	Async::Interrupt module, which works with most event loops. It will not
		430	work with inherently broken event loops such as Event or Event::Lib (and
		431	not with POE currently, as POE does it's own workaround with one-second
		432	latency). For those, you just have to suffer the delays.
		433
364	CHILD PROCESS WATCHERS	434	CHILD PROCESS WATCHERS
		435	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		436
365	You can also watch on a child process exit and catch its exit status.	437	You can also watch on a child process exit and catch its exit status.
366		438
367	The child process is specified by the "pid" argument (if set to 0, it	439	The child process is specified by the "pid" argument (one some backends,
368	watches for any child process exit). The watcher will triggered only	440	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	441	The watcher will be triggered only when the child process has finished
370	on any trace events (stopped/continued).	442	and an exit status is available, not on any trace events
		443	(stopped/continued).
371		444
372	The callback will be called with the pid and exit status (as returned by	445	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	446	waitpid), so unlike other watcher types, you can rely on child watcher
374	callback arguments.	447	callback arguments.
375		448
…		…
380		453
381	There is a slight catch to child watchers, however: you usually start	454	There is a slight catch to child watchers, however: you usually start
382	them after the child process was created, and this means the process	455	them after the child process was created, and this means the process
383	could have exited already (and no SIGCHLD will be sent anymore).	456	could have exited already (and no SIGCHLD will be sent anymore).
384		457
385	Not all event models handle this correctly (POE doesn't), but even for	458	Not all event models handle this correctly (neither POE nor IO::Async
		459	do, see their AnyEvent::Impl manpages for details), but even for event
386	event models that do handle this correctly, they usually need to be	460	models that do handle this correctly, they usually need to be loaded
387	loaded before the process exits (i.e. before you fork in the first	461	before the process exits (i.e. before you fork in the first place).
388	place).	462	AnyEvent's pure perl event loop handles all cases correctly regardless
		463	of when you start the watcher.
389		464
390	This means you cannot create a child watcher as the very first thing in	465	This means you cannot create a child watcher as the very first thing in
391	an AnyEvent program, you have to create at least one watcher before	466	an AnyEvent program, you have to create at least one watcher before
392	you "fork" the child (alternatively, you can call "AnyEvent::detect").	467	you "fork" the child (alternatively, you can call "AnyEvent::detect").
		468
		469	As most event loops do not support waiting for child events, they will
		470	be emulated by AnyEvent in most cases, in which the latency and race
		471	problems mentioned in the description of signal watchers apply.
393		472
394	Example: fork a process and wait for it	473	Example: fork a process and wait for it
395		474
396	my $done = AnyEvent->condvar;	475	my $done = AnyEvent->condvar;
397		476
…		…
408		487
409	# do something else, then wait for process exit	488	# do something else, then wait for process exit
410	$done->recv;	489	$done->recv;
411		490
412	IDLE WATCHERS	491	IDLE WATCHERS
413	Sometimes there is a need to do something, but it is not so important to	492	$w = AnyEvent->idle (cb => <callback>);
414	do it instantly, but only when there is nothing better to do. This
415	"nothing better to do" is usually defined to be "no other events need
416	attention by the event loop".
417		493
418	Idle watchers ideally get invoked when the event loop has nothing better	494	Repeatedly invoke the callback after the process becomes idle, until
419	to do, just before it would block the process to wait for new events.	495	either the watcher is destroyed or new events have been detected.
420	Instead of blocking, the idle watcher is invoked.
421		496
422	Most event loops unfortunately do not really support idle watchers (only	497	Idle watchers are useful when there is a need to do something, but it is
		498	not so important (or wise) to do it instantly. The callback will be
		499	invoked only when there is "nothing better to do", which is usually
		500	defined as "all outstanding events have been handled and no new events
		501	have been detected". That means that idle watchers ideally get invoked
		502	when the event loop has just polled for new events but none have been
		503	detected. Instead of blocking to wait for more events, the idle watchers
		504	will be invoked.
		505
		506	Unfortunately, most event loops do not really support idle watchers
423	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent	507	(only EV, Event and Glib do it in a usable fashion) - for the rest,
424	will simply call the callback "from time to time".	508	AnyEvent will simply call the callback "from time to time".
425		509
426	Example: read lines from STDIN, but only process them when the program	510	Example: read lines from STDIN, but only process them when the program
427	is otherwise idle:	511	is otherwise idle:
428		512
429	my @lines; # read data	513	my @lines; # read data
…		…
442	}	526	}
443	});	527	});
444	});	528	});
445		529
446	CONDITION VARIABLES	530	CONDITION VARIABLES
		531	$cv = AnyEvent->condvar;
		532
		533	$cv->send (<list>);
		534	my @res = $cv->recv;
		535
447	If you are familiar with some event loops you will know that all of them	536	If you are familiar with some event loops you will know that all of them
448	require you to run some blocking "loop", "run" or similar function that	537	require you to run some blocking "loop", "run" or similar function that
449	will actively watch for new events and call your callbacks.	538	will actively watch for new events and call your callbacks.
450		539
451	AnyEvent is different, it expects somebody else to run the event loop	540	AnyEvent is slightly different: it expects somebody else to run the
452	and will only block when necessary (usually when told by the user).	541	event loop and will only block when necessary (usually when told by the
		542	user).
453		543
454	The instrument to do that is called a "condition variable", so called	544	The tool to do that is called a "condition variable", so called because
455	because they represent a condition that must become true.	545	they represent a condition that must become true.
		546
		547	Now is probably a good time to look at the examples further below.
456		548
457	Condition variables can be created by calling the "AnyEvent->condvar"	549	Condition variables can be created by calling the "AnyEvent->condvar"
458	method, usually without arguments. The only argument pair allowed is	550	method, usually without arguments. The only argument pair allowed is
459
460	"cb", which specifies a callback to be called when the condition	551	"cb", which specifies a callback to be called when the condition
461	variable becomes true, with the condition variable as the first argument	552	variable becomes true, with the condition variable as the first argument
462	(but not the results).	553	(but not the results).
463		554
464	After creation, the condition variable is "false" until it becomes	555	After creation, the condition variable is "false" until it becomes
465	"true" by calling the "send" method (or calling the condition variable	556	"true" by calling the "send" method (or calling the condition variable
466	as if it were a callback, read about the caveats in the description for	557	as if it were a callback, read about the caveats in the description for
467	the "->send" method).	558	the "->send" method).
468		559
469	Condition variables are similar to callbacks, except that you can	560	Since condition variables are the most complex part of the AnyEvent API,
470	optionally wait for them. They can also be called merge points - points	561	here are some different mental models of what they are - pick the ones
471	in time where multiple outstanding events have been processed. And yet	562	you can connect to:
472	another way to call them is transactions - each condition variable can	563
473	be used to represent a transaction, which finishes at some point and	564	* Condition variables are like callbacks - you can call them (and pass
474	delivers a result.	565	them instead of callbacks). Unlike callbacks however, you can also
		566	wait for them to be called.
		567
		568	* Condition variables are signals - one side can emit or send them,
		569	the other side can wait for them, or install a handler that is
		570	called when the signal fires.
		571
		572	* Condition variables are like "Merge Points" - points in your program
		573	where you merge multiple independent results/control flows into one.
		574
		575	* Condition variables represent a transaction - function that start
		576	some kind of transaction can return them, leaving the caller the
		577	choice between waiting in a blocking fashion, or setting a callback.
		578
		579	* Condition variables represent future values, or promises to deliver
		580	some result, long before the result is available.
475		581
476	Condition variables are very useful to signal that something has	582	Condition variables are very useful to signal that something has
477	finished, for example, if you write a module that does asynchronous http	583	finished, for example, if you write a module that does asynchronous http
478	requests, then a condition variable would be the ideal candidate to	584	requests, then a condition variable would be the ideal candidate to
479	signal the availability of results. The user can either act when the	585	signal the availability of results. The user can either act when the
…		…
500	which eventually calls "-> send", and the "consumer side", which waits	606	which eventually calls "-> send", and the "consumer side", which waits
501	for the send to occur.	607	for the send to occur.
502		608
503	Example: wait for a timer.	609	Example: wait for a timer.
504		610
505	# wait till the result is ready	611	# condition: "wait till the timer is fired"
506	my $result_ready = AnyEvent->condvar;	612	my $timer_fired = AnyEvent->condvar;
507		613
508	# do something such as adding a timer	614	# create the timer - we could wait for, say
509	# or socket watcher the calls $result_ready->send	615	# a handle becomign ready, or even an
510	# when the "result" is ready.	616	# AnyEvent::HTTP request to finish, but
511	# in this case, we simply use a timer:	617	# in this case, we simply use a timer:
512	my $w = AnyEvent->timer (	618	my $w = AnyEvent->timer (
513	after => 1,	619	after => 1,
514	cb => sub { $result_ready->send },	620	cb => sub { $timer_fired->send },
515	);	621	);
516		622
517	# this "blocks" (while handling events) till the callback	623	# this "blocks" (while handling events) till the callback
518	# calls send	624	# calls ->send
519	$result_ready->recv;	625	$timer_fired->recv;
520		626
521	Example: wait for a timer, but take advantage of the fact that condition	627	Example: wait for a timer, but take advantage of the fact that condition
522	variables are also code references.	628	variables are also callable directly.
523		629
524	my $done = AnyEvent->condvar;	630	my $done = AnyEvent->condvar;
525	my $delay = AnyEvent->timer (after => 5, cb => $done);	631	my $delay = AnyEvent->timer (after => 5, cb => $done);
526	$done->recv;	632	$done->recv;
527		633
…		…
533		639
534	...	640	...
535		641
536	my @info = $couchdb->info->recv;	642	my @info = $couchdb->info->recv;
537		643
538	And this is how you would just ste a callback to be called whenever the	644	And this is how you would just set a callback to be called whenever the
539	results are available:	645	results are available:
540		646
541	$couchdb->info->cb (sub {	647	$couchdb->info->cb (sub {
542	my @info = $_[0]->recv;	648	my @info = $_[0]->recv;
543	});	649	});
…		…
558		664
559	Any arguments passed to the "send" call will be returned by all	665	Any arguments passed to the "send" call will be returned by all
560	future "->recv" calls.	666	future "->recv" calls.
561		667
562	Condition variables are overloaded so one can call them directly (as	668	Condition variables are overloaded so one can call them directly (as
563	a code reference). Calling them directly is the same as calling	669	if they were a code reference). Calling them directly is the same as
564	"send". Note, however, that many C-based event loops do not handle	670	calling "send".
565	overloading, so as tempting as it may be, passing a condition
566	variable instead of a callback does not work. Both the pure perl and
567	EV loops support overloading, however, as well as all functions that
568	use perl to invoke a callback (as in AnyEvent::Socket and
569	AnyEvent::DNS for example).
570		671
571	$cv->croak ($error)	672	$cv->croak ($error)
572	Similar to send, but causes all call's to "->recv" to invoke	673	Similar to send, but causes all call's to "->recv" to invoke
573	"Carp::croak" with the given error message/object/scalar.	674	"Carp::croak" with the given error message/object/scalar.
574		675
575	This can be used to signal any errors to the condition variable	676	This can be used to signal any errors to the condition variable
576	user/consumer.	677	user/consumer. Doing it this way instead of calling "croak" directly
		678	delays the error detetcion, but has the overwhelmign advantage that
		679	it diagnoses the error at the place where the result is expected,
		680	and not deep in some event clalback without connection to the actual
		681	code causing the problem.
577		682
578	$cv->begin ([group callback])	683	$cv->begin ([group callback])
579	$cv->end	684	$cv->end
580	These two methods are EXPERIMENTAL and MIGHT CHANGE.
581
582	These two methods can be used to combine many transactions/events	685	These two methods can be used to combine many transactions/events
583	into one. For example, a function that pings many hosts in parallel	686	into one. For example, a function that pings many hosts in parallel
584	might want to use a condition variable for the whole process.	687	might want to use a condition variable for the whole process.
585		688
586	Every call to "->begin" will increment a counter, and every call to	689	Every call to "->begin" will increment a counter, and every call to
587	"->end" will decrement it. If the counter reaches 0 in "->end", the	690	"->end" will decrement it. If the counter reaches 0 in "->end", the
588	(last) callback passed to "begin" will be executed. That callback is	691	(last) callback passed to "begin" will be executed, passing the
589	supposed to call "->send", but that is not required. If no	692	condvar as first argument. That callback is supposed to call
		693	"->send", but that is not required. If no group callback was set,
590	callback was set, "send" will be called without any arguments.	694	"send" will be called without any arguments.
591		695
592	Let's clarify this with the ping example:	696	You can think of "$cv->send" giving you an OR condition (one call
		697	sends), while "$cv->begin" and "$cv->end" giving you an AND
		698	condition (all "begin" calls must be "end"'ed before the condvar
		699	sends).
		700
		701	Let's start with a simple example: you have two I/O watchers (for
		702	example, STDOUT and STDERR for a program), and you want to wait for
		703	both streams to close before activating a condvar:
593		704
594	my $cv = AnyEvent->condvar;	705	my $cv = AnyEvent->condvar;
595		706
		707	$cv->begin; # first watcher
		708	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		709	defined sysread $fh1, my $buf, 4096
		710	or $cv->end;
		711	});
		712
		713	$cv->begin; # second watcher
		714	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		715	defined sysread $fh2, my $buf, 4096
		716	or $cv->end;
		717	});
		718
		719	$cv->recv;
		720
		721	This works because for every event source (EOF on file handle),
		722	there is one call to "begin", so the condvar waits for all calls to
		723	"end" before sending.
		724
		725	The ping example mentioned above is slightly more complicated, as
		726	the there are results to be passwd back, and the number of tasks
		727	that are begung can potentially be zero:
		728
		729	my $cv = AnyEvent->condvar;
		730
596	my %result;	731	my %result;
597	$cv->begin (sub { $cv->send (\%result) });	732	$cv->begin (sub { shift->send (\%result) });
598		733
599	for my $host (@list_of_hosts) {	734	for my $host (@list_of_hosts) {
600	$cv->begin;	735	$cv->begin;
601	ping_host_then_call_callback $host, sub {	736	ping_host_then_call_callback $host, sub {
602	$result{$host} = ...;	737	$result{$host} = ...;
…		…
617	the loop, which serves two important purposes: first, it sets the	752	the loop, which serves two important purposes: first, it sets the
618	callback to be called once the counter reaches 0, and second, it	753	callback to be called once the counter reaches 0, and second, it
619	ensures that "send" is called even when "no" hosts are being pinged	754	ensures that "send" is called even when "no" hosts are being pinged
620	(the loop doesn't execute once).	755	(the loop doesn't execute once).
621		756
622	This is the general pattern when you "fan out" into multiple	757	This is the general pattern when you "fan out" into multiple (but
623	subrequests: use an outer "begin"/"end" pair to set the callback and	758	potentially none) subrequests: use an outer "begin"/"end" pair to
624	ensure "end" is called at least once, and then, for each subrequest	759	set the callback and ensure "end" is called at least once, and then,
625	you start, call "begin" and for each subrequest you finish, call	760	for each subrequest you start, call "begin" and for each subrequest
626	"end".	761	you finish, call "end".
627		762
628	METHODS FOR CONSUMERS	763	METHODS FOR CONSUMERS
629	These methods should only be used by the consuming side, i.e. the code	764	These methods should only be used by the consuming side, i.e. the code
630	awaits the condition.	765	awaits the condition.
631		766
…		…
640	function will call "croak".	775	function will call "croak".
641		776
642	In list context, all parameters passed to "send" will be returned,	777	In list context, all parameters passed to "send" will be returned,
643	in scalar context only the first one will be returned.	778	in scalar context only the first one will be returned.
644		779
		780	Note that doing a blocking wait in a callback is not supported by
		781	any event loop, that is, recursive invocation of a blocking "->recv"
		782	is not allowed, and the "recv" call will "croak" if such a condition
		783	is detected. This condition can be slightly loosened by using
		784	Coro::AnyEvent, which allows you to do a blocking "->recv" from any
		785	thread that doesn't run the event loop itself.
		786
645	Not all event models support a blocking wait - some die in that case	787	Not all event models support a blocking wait - some die in that case
646	(programs might want to do that to stay interactive), so *if you are	788	(programs might want to do that to stay interactive), so *if you are
647	using this from a module, never require a blocking wait*, but let	789	using this from a module, never require a blocking wait*. Instead,
648	the caller decide whether the call will block or not (for example,	790	let the caller decide whether the call will block or not (for
649	by coupling condition variables with some kind of request results	791	example, by coupling condition variables with some kind of request
650	and supporting callbacks so the caller knows that getting the result	792	results and supporting callbacks so the caller knows that getting
651	will not block, while still supporting blocking waits if the caller	793	the result will not block, while still supporting blocking waits if
652	so desires).	794	the caller so desires).
653
654	Another reason never to "->recv" in a module is that you cannot
655	sensibly have two "->recv"'s in parallel, as that would require
656	multiple interpreters or coroutines/threads, none of which
657	"AnyEvent" can supply.
658
659	The Coro module, however, can and does supply coroutines and, in
660	fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe
661	versions and also integrates coroutines into AnyEvent, making
662	blocking "->recv" calls perfectly safe as long as they are done from
663	another coroutine (one that doesn't run the event loop).
664		795
665	You can ensure that "-recv" never blocks by setting a callback and	796	You can ensure that "-recv" never blocks by setting a callback and
666	only calling "->recv" from within that callback (or at a later	797	only calling "->recv" from within that callback (or at a later
667	time). This will work even when the event loop does not support	798	time). This will work even when the event loop does not support
668	blocking waits otherwise.	799	blocking waits otherwise.
…		…
673		804
674	$cb = $cv->cb ($cb->($cv))	805	$cb = $cv->cb ($cb->($cv))
675	This is a mutator function that returns the callback set and	806	This is a mutator function that returns the callback set and
676	optionally replaces it before doing so.	807	optionally replaces it before doing so.
677		808
678	The callback will be called when the condition becomes "true", i.e.	809	The callback will be called when the condition becomes (or already
679	when "send" or "croak" are called, with the only argument being the	810	was) "true", i.e. when "send" or "croak" are called (or were
680	condition variable itself. Calling "recv" inside the callback or at	811	called), with the only argument being the condition variable itself.
		812	Calling "recv" inside the callback or at any later time is
681	any later time is guaranteed not to block.	813	guaranteed not to block.
		814
		815	SUPPORTED EVENT LOOPS/BACKENDS
		816	The available backend classes are (every class has its own manpage):
		817
		818	Backends that are autoprobed when no other event loop can be found.
		819	EV is the preferred backend when no other event loop seems to be in
		820	use. If EV is not installed, then AnyEvent will fall back to its own
		821	pure-perl implementation, which is available everywhere as it comes
		822	with AnyEvent itself.
		823
		824	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		825	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		826
		827	Backends that are transparently being picked up when they are used.
		828	These will be used when they are currently loaded when the first
		829	watcher is created, in which case it is assumed that the application
		830	is using them. This means that AnyEvent will automatically pick the
		831	right backend when the main program loads an event module before
		832	anything starts to create watchers. Nothing special needs to be done
		833	by the main program.
		834
		835	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		836	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		837	AnyEvent::Impl::Tk based on Tk, very broken.
		838	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		839	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		840	AnyEvent::Impl::Irssi used when running within irssi.
		841
		842	Backends with special needs.
		843	Qt requires the Qt::Application to be instantiated first, but will
		844	otherwise be picked up automatically. As long as the main program
		845	instantiates the application before any AnyEvent watchers are
		846	created, everything should just work.
		847
		848	AnyEvent::Impl::Qt based on Qt.
		849
		850	Support for IO::Async can only be partial, as it is too broken and
		851	architecturally limited to even support the AnyEvent API. It also is
		852	the only event loop that needs the loop to be set explicitly, so it
		853	can only be used by a main program knowing about AnyEvent. See
		854	AnyEvent::Impl::Async for the gory details.
		855
		856	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		857
		858	Event loops that are indirectly supported via other backends.
		859	Some event loops can be supported via other modules:
		860
		861	There is no direct support for WxWidgets (Wx) or Prima.
		862
		863	WxWidgets has no support for watching file handles. However, you can
		864	use WxWidgets through the POE adaptor, as POE has a Wx backend that
		865	simply polls 20 times per second, which was considered to be too
		866	horrible to even consider for AnyEvent.
		867
		868	Prima is not supported as nobody seems to be using it, but it has a
		869	POE backend, so it can be supported through POE.
		870
		871	AnyEvent knows about both Prima and Wx, however, and will try to
		872	load POE when detecting them, in the hope that POE will pick them
		873	up, in which case everything will be automatic.
682		874
683	GLOBAL VARIABLES AND FUNCTIONS	875	GLOBAL VARIABLES AND FUNCTIONS
		876	These are not normally required to use AnyEvent, but can be useful to
		877	write AnyEvent extension modules.
		878
684	$AnyEvent::MODEL	879	$AnyEvent::MODEL
685	Contains "undef" until the first watcher is being created. Then it	880	Contains "undef" until the first watcher is being created, before
		881	the backend has been autodetected.
		882
686	contains the event model that is being used, which is the name of	883	Afterwards it contains the event model that is being used, which is
687	the Perl class implementing the model. This class is usually one of	884	the name of the Perl class implementing the model. This class is
688	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	885	usually one of the "AnyEvent::Impl:xxx" modules, but can be any
689	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	886	other class in the case AnyEvent has been extended at runtime (e.g.
690		887	in rxvt-unicode it will be "urxvt::anyevent").
691	The known classes so far are:
692
693	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
694	AnyEvent::Impl::Event based on Event, second best choice.
695	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
696	AnyEvent::Impl::Glib based on Glib, third-best choice.
697	AnyEvent::Impl::Tk based on Tk, very bad choice.
698	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
699	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
700	AnyEvent::Impl::POE based on POE, not generic enough for full support.
701
702	There is no support for WxWidgets, as WxWidgets has no support for
703	watching file handles. However, you can use WxWidgets through the
704	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
705	second, which was considered to be too horrible to even consider for
706	AnyEvent. Likewise, other POE backends can be used by AnyEvent by
707	using it's adaptor.
708
709	AnyEvent knows about Prima and Wx and will try to use POE when
710	autodetecting them.
711		888
712	AnyEvent::detect	889	AnyEvent::detect
713	Returns $AnyEvent::MODEL, forcing autodetection of the event model	890	Returns $AnyEvent::MODEL, forcing autodetection of the event model
714	if necessary. You should only call this function right before you	891	if necessary. You should only call this function right before you
715	would have created an AnyEvent watcher anyway, that is, as late as	892	would have created an AnyEvent watcher anyway, that is, as late as
716	possible at runtime.	893	possible at runtime, and not e.g. while initialising of your module.
		894
		895	If you need to do some initialisation before AnyEvent watchers are
		896	created, use "post_detect".
717		897
718	$guard = AnyEvent::post_detect { BLOCK }	898	$guard = AnyEvent::post_detect { BLOCK }
719	Arranges for the code block to be executed as soon as the event	899	Arranges for the code block to be executed as soon as the event
720	model is autodetected (or immediately if this has already happened).	900	model is autodetected (or immediately if this has already happened).
721		901
		902	The block will be executed after the actual backend has been
		903	detected ($AnyEvent::MODEL is set), but before any watchers have
		904	been created, so it is possible to e.g. patch @AnyEvent::ISA or do
		905	other initialisations - see the sources of AnyEvent::Strict or
		906	AnyEvent::AIO to see how this is used.
		907
		908	The most common usage is to create some global watchers, without
		909	forcing event module detection too early, for example, AnyEvent::AIO
		910	creates and installs the global IO::AIO watcher in a "post_detect"
		911	block to avoid autodetecting the event module at load time.
		912
722	If called in scalar or list context, then it creates and returns an	913	If called in scalar or list context, then it creates and returns an
723	object that automatically removes the callback again when it is	914	object that automatically removes the callback again when it is
		915	destroyed (or "undef" when the hook was immediately executed). See
724	destroyed. See Coro::BDB for a case where this is useful.	916	AnyEvent::AIO for a case where this is useful.
		917
		918	Example: Create a watcher for the IO::AIO module and store it in
		919	$WATCHER. Only do so after the event loop is initialised, though.
		920
		921	our WATCHER;
		922
		923	my $guard = AnyEvent::post_detect {
		924	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		925	};
		926
		927	# the \|\|= is important in case post_detect immediately runs the block,
		928	# as to not clobber the newly-created watcher. assigning both watcher and
		929	# post_detect guard to the same variable has the advantage of users being
		930	# able to just C<undef $WATCHER> if the watcher causes them grief.
		931
		932	$WATCHER \|\|= $guard;
725		933
726	@AnyEvent::post_detect	934	@AnyEvent::post_detect
727	If there are any code references in this array (you can "push" to it	935	If there are any code references in this array (you can "push" to it
728	before or after loading AnyEvent), then they will called directly	936	before or after loading AnyEvent), then they will called directly
729	after the event loop has been chosen.	937	after the event loop has been chosen.
730		938
731	You should check $AnyEvent::MODEL before adding to this array,	939	You should check $AnyEvent::MODEL before adding to this array,
732	though: if it contains a true value then the event loop has already	940	though: if it is defined then the event loop has already been
733	been detected, and the array will be ignored.	941	detected, and the array will be ignored.
734		942
735	Best use "AnyEvent::post_detect { BLOCK }" instead.	943	Best use "AnyEvent::post_detect { BLOCK }" when your application
		944	allows it, as it takes care of these details.
		945
		946	This variable is mainly useful for modules that can do something
		947	useful when AnyEvent is used and thus want to know when it is
		948	initialised, but do not need to even load it by default. This array
		949	provides the means to hook into AnyEvent passively, without loading
		950	it.
		951
		952	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		953	together, you could put this into Coro (this is the actual code used
		954	by Coro to accomplish this):
		955
		956	if (defined $AnyEvent::MODEL) {
		957	# AnyEvent already initialised, so load Coro::AnyEvent
		958	require Coro::AnyEvent;
		959	} else {
		960	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		961	# as soon as it is
		962	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		963	}
736		964
737	WHAT TO DO IN A MODULE	965	WHAT TO DO IN A MODULE
738	As a module author, you should "use AnyEvent" and call AnyEvent methods	966	As a module author, you should "use AnyEvent" and call AnyEvent methods
739	freely, but you should not load a specific event module or rely on it.	967	freely, but you should not load a specific event module or rely on it.
740		968
…		…
791	variable somewhere, waiting for it, and sending it when the program	1019	variable somewhere, waiting for it, and sending it when the program
792	should exit cleanly.	1020	should exit cleanly.
793		1021
794	OTHER MODULES	1022	OTHER MODULES
795	The following is a non-exhaustive list of additional modules that use	1023	The following is a non-exhaustive list of additional modules that use
796	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1024	AnyEvent as a client and can therefore be mixed easily with other
797	in the same program. Some of the modules come with AnyEvent, some are	1025	AnyEvent modules and other event loops in the same program. Some of the
798	available via CPAN.	1026	modules come as part of AnyEvent, the others are available via CPAN.
799		1027
800	AnyEvent::Util	1028	AnyEvent::Util
801	Contains various utility functions that replace often-used but	1029	Contains various utility functions that replace often-used but
802	blocking functions such as "inet_aton" by event-/callback-based	1030	blocking functions such as "inet_aton" by event-/callback-based
803	versions.	1031	versions.
…		…
809	more.	1037	more.
810		1038
811	AnyEvent::Handle	1039	AnyEvent::Handle
812	Provide read and write buffers, manages watchers for reads and	1040	Provide read and write buffers, manages watchers for reads and
813	writes, supports raw and formatted I/O, I/O queued and fully	1041	writes, supports raw and formatted I/O, I/O queued and fully
814	transparent and non-blocking SSL/TLS.	1042	transparent and non-blocking SSL/TLS (via AnyEvent::TLS.
815		1043
816	AnyEvent::DNS	1044	AnyEvent::DNS
817	Provides rich asynchronous DNS resolver capabilities.	1045	Provides rich asynchronous DNS resolver capabilities.
818		1046
		1047	AnyEvent::HTTP, AnyEvent::IRC, AnyEvent::XMPP, AnyEvent::GPSD,
		1048	AnyEvent::IGS, AnyEvent::FCP
		1049	Implement event-based interfaces to the protocols of the same name
		1050	(for the curious, IGS is the International Go Server and FCP is the
		1051	Freenet Client Protocol).
		1052
		1053	AnyEvent::Handle::UDP
		1054	Here be danger!
		1055
		1056	As Pauli would put it, "Not only is it not right, it's not even
		1057	wrong!" - there are so many things wrong with AnyEvent::Handle::UDP,
		1058	most notably it's use of a stream-based API with a protocol that
		1059	isn't streamable, that the only way to improve it is to delete it.
		1060
		1061	It features data corruption (but typically only under load) and
		1062	general confusion. On top, the author is not only clueless about UDP
		1063	but also fact-resistant - some gems of his understanding: "connect
		1064	doesn't work with UDP", "UDP packets are not IP packets", "UDP only
		1065	has datagrams, not packets", "I don't need to implement proper error
		1066	checking as UDP doesn't support error checking" and so on - he
		1067	doesn't even understand what's wrong with his module when it is
		1068	explained to him.
		1069
819	AnyEvent::HTTP	1070	AnyEvent::DBI
820	A simple-to-use HTTP library that is capable of making a lot of	1071	Executes DBI requests asynchronously in a proxy process for you,
821	concurrent HTTP requests.	1072	notifying you in an event-bnased way when the operation is finished.
		1073
		1074	AnyEvent::AIO
		1075	Truly asynchronous (as opposed to non-blocking) I/O, should be in
		1076	the toolbox of every event programmer. AnyEvent::AIO transparently
		1077	fuses IO::AIO and AnyEvent together, giving AnyEvent access to
		1078	event-based file I/O, and much more.
822		1079
823	AnyEvent::HTTPD	1080	AnyEvent::HTTPD
824	Provides a simple web application server framework.	1081	A simple embedded webserver.
825		1082
826	AnyEvent::FastPing	1083	AnyEvent::FastPing
827	The fastest ping in the west.	1084	The fastest ping in the west.
828		1085
829	AnyEvent::DBI
830	Executes DBI requests asynchronously in a proxy process.
831
832	AnyEvent::AIO
833	Truly asynchronous I/O, should be in the toolbox of every event
834	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
835	together.
836
837	AnyEvent::BDB
838	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently
839	fuses BDB and AnyEvent together.
840
841	AnyEvent::GPSD
842	A non-blocking interface to gpsd, a daemon delivering GPS
843	information.
844
845	AnyEvent::IGS
846	A non-blocking interface to the Internet Go Server protocol (used by
847	App::IGS).
848
849	AnyEvent::IRC
850	AnyEvent based IRC client module family (replacing the older
851	Net::IRC3).
852
853	Net::XMPP2
854	AnyEvent based XMPP (Jabber protocol) module family.
855
856	Net::FCP
857	AnyEvent-based implementation of the Freenet Client Protocol,
858	birthplace of AnyEvent.
859
860	Event::ExecFlow
861	High level API for event-based execution flow control.
862
863	Coro	1086	Coro
864	Has special support for AnyEvent via Coro::AnyEvent.	1087	Has special support for AnyEvent via Coro::AnyEvent.
865		1088
866	IO::Lambda	1089	SIMPLIFIED AE API
867	The lambda approach to I/O - don't ask, look there. Can use	1090	Starting with version 5.0, AnyEvent officially supports a second, much
868	AnyEvent.	1091	simpler, API that is designed to reduce the calling, typing and memory
		1092	overhead by using function call syntax and a fixed number of parameters.
		1093
		1094	See the AE manpage for details.
869		1095
870	ERROR AND EXCEPTION HANDLING	1096	ERROR AND EXCEPTION HANDLING
871	In general, AnyEvent does not do any error handling - it relies on the	1097	In general, AnyEvent does not do any error handling - it relies on the
872	caller to do that if required. The AnyEvent::Strict module (see also the	1098	caller to do that if required. The AnyEvent::Strict module (see also the
873	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict	1099	"PERL_ANYEVENT_STRICT" environment variable, below) provides strict
…		…
901	by "PERL_ANYEVENT_MODEL".	1127	by "PERL_ANYEVENT_MODEL".
902		1128
903	When set to 2 or higher, cause AnyEvent to report to STDERR which	1129	When set to 2 or higher, cause AnyEvent to report to STDERR which
904	event model it chooses.	1130	event model it chooses.
905		1131
		1132	When set to 8 or higher, then AnyEvent will report extra information
		1133	on which optional modules it loads and how it implements certain
		1134	features.
		1135
906	"PERL_ANYEVENT_STRICT"	1136	"PERL_ANYEVENT_STRICT"
907	AnyEvent does not do much argument checking by default, as thorough	1137	AnyEvent does not do much argument checking by default, as thorough
908	argument checking is very costly. Setting this variable to a true	1138	argument checking is very costly. Setting this variable to a true
909	value will cause AnyEvent to load "AnyEvent::Strict" and then to	1139	value will cause AnyEvent to load "AnyEvent::Strict" and then to
910	thoroughly check the arguments passed to most method calls. If it	1140	thoroughly check the arguments passed to most method calls. If it
911	finds any problems it will croak.	1141	finds any problems, it will croak.
912		1142
913	In other words, enables "strict" mode.	1143	In other words, enables "strict" mode.
914		1144
915	Unlike "use strict", it is definitely recommended ot keep it off in	1145	Unlike "use strict" (or it's modern cousin, "use common::sense", it
916	production. Keeping "PERL_ANYEVENT_STRICT=1" in your environment	1146	is definitely recommended to keep it off in production. Keeping
		1147	"PERL_ANYEVENT_STRICT=1" in your environment while developing
917	while developing programs can be very useful, however.	1148	programs can be very useful, however.
918		1149
919	"PERL_ANYEVENT_MODEL"	1150	"PERL_ANYEVENT_MODEL"
920	This can be used to specify the event model to be used by AnyEvent,	1151	This can be used to specify the event model to be used by AnyEvent,
921	before auto detection and -probing kicks in. It must be a string	1152	before auto detection and -probing kicks in. It must be a string
922	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	1153	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
…		…
963	EDNS0 in its DNS requests.	1194	EDNS0 in its DNS requests.
964		1195
965	"PERL_ANYEVENT_MAX_FORKS"	1196	"PERL_ANYEVENT_MAX_FORKS"
966	The maximum number of child processes that	1197	The maximum number of child processes that
967	"AnyEvent::Util::fork_call" will create in parallel.	1198	"AnyEvent::Util::fork_call" will create in parallel.
		1199
		1200	"PERL_ANYEVENT_MAX_OUTSTANDING_DNS"
		1201	The default value for the "max_outstanding" parameter for the
		1202	default DNS resolver - this is the maximum number of parallel DNS
		1203	requests that are sent to the DNS server.
		1204
		1205	"PERL_ANYEVENT_RESOLV_CONF"
		1206	The file to use instead of /etc/resolv.conf (or OS-specific
		1207	configuration) in the default resolver. When set to the empty
		1208	string, no default config will be used.
		1209
		1210	"PERL_ANYEVENT_CA_FILE", "PERL_ANYEVENT_CA_PATH".
		1211	When neither "ca_file" nor "ca_path" was specified during
		1212	AnyEvent::TLS context creation, and either of these environment
		1213	variables exist, they will be used to specify CA certificate
		1214	locations instead of a system-dependent default.
		1215
		1216	"PERL_ANYEVENT_AVOID_GUARD" and "PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT"
		1217	When these are set to 1, then the respective modules are not loaded.
		1218	Mostly good for testing AnyEvent itself.
968		1219
969	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1220	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
970	This is an advanced topic that you do not normally need to use AnyEvent	1221	This is an advanced topic that you do not normally need to use AnyEvent
971	in a module. This section is only of use to event loop authors who want	1222	in a module. This section is only of use to event loop authors who want
972	to provide AnyEvent compatibility.	1223	to provide AnyEvent compatibility.
…		…
1027	warn "read: $input\n"; # output what has been read	1278	warn "read: $input\n"; # output what has been read
1028	$cv->send if $input =~ /^q/i; # quit program if /^q/i	1279	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1029	},	1280	},
1030	);	1281	);
1031		1282
1032	my $time_watcher; # can only be used once
1033
1034	sub new_timer {
1035	$timer = AnyEvent->timer (after => 1, cb => sub {	1283	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1036	warn "timeout\n"; # print 'timeout' about every second	1284	warn "timeout\n"; # print 'timeout' at most every second
1037	&new_timer; # and restart the time
1038	});
1039	}	1285	});
1040
1041	new_timer; # create first timer
1042		1286
1043	$cv->recv; # wait until user enters /^q/i	1287	$cv->recv; # wait until user enters /^q/i
1044		1288
1045	REAL-WORLD EXAMPLE	1289	REAL-WORLD EXAMPLE
1046	Consider the Net::FCP module. It features (among others) the following	1290	Consider the Net::FCP module. It features (among others) the following
…		…
1118		1362
1119	The actual code goes further and collects all errors ("die"s,	1363	The actual code goes further and collects all errors ("die"s,
1120	exceptions) that occurred during request processing. The "result" method	1364	exceptions) that occurred during request processing. The "result" method
1121	detects whether an exception as thrown (it is stored inside the $txn	1365	detects whether an exception as thrown (it is stored inside the $txn
1122	object) and just throws the exception, which means connection errors and	1366	object) and just throws the exception, which means connection errors and
1123	other problems get reported tot he code that tries to use the result,	1367	other problems get reported to the code that tries to use the result,
1124	not in a random callback.	1368	not in a random callback.
1125		1369
1126	All of this enables the following usage styles:	1370	All of this enables the following usage styles:
1127		1371
1128	1. Blocking:	1372	1. Blocking:
…		…
1173	through AnyEvent. The benchmark creates a lot of timers (with a zero	1417	through AnyEvent. The benchmark creates a lot of timers (with a zero
1174	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1418	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1175	which it is), lets them fire exactly once and destroys them again.	1419	which it is), lets them fire exactly once and destroys them again.
1176		1420
1177	Source code for this benchmark is found as eg/bench in the AnyEvent	1421	Source code for this benchmark is found as eg/bench in the AnyEvent
1178	distribution.	1422	distribution. It uses the AE interface, which makes a real difference
		1423	for the EV and Perl backends only.
1179		1424
1180	Explanation of the columns	1425	Explanation of the columns
1181	watcher is the number of event watchers created/destroyed. Since	1426	watcher is the number of event watchers created/destroyed. Since
1182	different event models feature vastly different performances, each event	1427	different event models feature vastly different performances, each event
1183	loop was given a number of watchers so that overall runtime is	1428	loop was given a number of watchers so that overall runtime is
…		…
1202	destroy is the time, in microseconds, that it takes to destroy a	1447	destroy is the time, in microseconds, that it takes to destroy a
1203	single watcher.	1448	single watcher.
1204		1449
1205	Results	1450	Results
1206	name watchers bytes create invoke destroy comment	1451	name watchers bytes create invoke destroy comment
1207	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	1452	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1208	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1453	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1209	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1454	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1210	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1455	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1211	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1456	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1212	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1457	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		1458	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		1459	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1213	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1460	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1214	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1461	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1215	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1462	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1216	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1463	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1217		1464
1218	Discussion	1465	Discussion
1219	The benchmark does not measure scalability of the event loop very	1466	The benchmark does not measure scalability of the event loop very
1220	well. For example, a select-based event loop (such as the pure perl one)	1467	well. For example, a select-based event loop (such as the pure perl one)
1221	can never compete with an event loop that uses epoll when the number of	1468	can never compete with an event loop that uses epoll when the number of
…		…
1232	benchmark machine, handling an event takes roughly 1600 CPU cycles with	1479	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1233	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000	1480	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000
1234	CPU cycles with POE.	1481	CPU cycles with POE.
1235		1482
1236	"EV" is the sole leader regarding speed and memory use, which are both	1483	"EV" is the sole leader regarding speed and memory use, which are both
1237	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1484	maximal/minimal, respectively. When using the AE API there is zero
		1485	overhead (when going through the AnyEvent API create is about 5-6 times
		1486	slower, with other times being equal, so still uses far less memory than
1238	far less memory than any other event loop and is still faster than Event	1487	any other event loop and is still faster than Event natively).
1239	natively.
1240		1488
1241	The pure perl implementation is hit in a few sweet spots (both the	1489	The pure perl implementation is hit in a few sweet spots (both the
1242	constant timeout and the use of a single fd hit optimisations in the	1490	constant timeout and the use of a single fd hit optimisations in the
1243	perl interpreter and the backend itself). Nevertheless this shows that	1491	perl interpreter and the backend itself). Nevertheless this shows that
1244	it adds very little overhead in itself. Like any select-based backend	1492	it adds very little overhead in itself. Like any select-based backend
…		…
1246	few of them active), of course, but this was not subject of this	1494	few of them active), of course, but this was not subject of this
1247	benchmark.	1495	benchmark.
1248		1496
1249	The "Event" module has a relatively high setup and callback invocation	1497	The "Event" module has a relatively high setup and callback invocation
1250	cost, but overall scores in on the third place.	1498	cost, but overall scores in on the third place.
		1499
		1500	"IO::Async" performs admirably well, about on par with "Event", even
		1501	when using its pure perl backend.
1251		1502
1252	"Glib"'s memory usage is quite a bit higher, but it features a faster	1503	"Glib"'s memory usage is quite a bit higher, but it features a faster
1253	callback invocation and overall ends up in the same class as "Event".	1504	callback invocation and overall ends up in the same class as "Event".
1254	However, Glib scales extremely badly, doubling the number of watchers	1505	However, Glib scales extremely badly, doubling the number of watchers
1255	increases the processing time by more than a factor of four, making it	1506	increases the processing time by more than a factor of four, making it
…		…
1311	In this benchmark, we use 10000 socket pairs (20000 sockets), of which	1562	In this benchmark, we use 10000 socket pairs (20000 sockets), of which
1312	100 (1%) are active. This mirrors the activity of large servers with	1563	100 (1%) are active. This mirrors the activity of large servers with
1313	many connections, most of which are idle at any one point in time.	1564	many connections, most of which are idle at any one point in time.
1314		1565
1315	Source code for this benchmark is found as eg/bench2 in the AnyEvent	1566	Source code for this benchmark is found as eg/bench2 in the AnyEvent
1316	distribution.	1567	distribution. It uses the AE interface, which makes a real difference
		1568	for the EV and Perl backends only.
1317		1569
1318	Explanation of the columns	1570	Explanation of the columns
1319	sockets is the number of sockets, and twice the number of "servers"	1571	sockets is the number of sockets, and twice the number of "servers"
1320	(as each server has a read and write socket end).	1572	(as each server has a read and write socket end).
1321		1573
…		…
1326	single "request", that is, reading the token from the pipe and	1578	single "request", that is, reading the token from the pipe and
1327	forwarding it to another server. This includes deleting the old timeout	1579	forwarding it to another server. This includes deleting the old timeout
1328	and creating a new one that moves the timeout into the future.	1580	and creating a new one that moves the timeout into the future.
1329		1581
1330	Results	1582	Results
1331	name sockets create request	1583	name sockets create request
1332	EV 20000 69.01 11.16	1584	EV 20000 62.66 7.99
1333	Perl 20000 73.32 35.87	1585	Perl 20000 68.32 32.64
1334	Event 20000 212.62 257.32	1586	IOAsync 20000 174.06 101.15 epoll
1335	Glib 20000 651.16 1896.30	1587	IOAsync 20000 174.67 610.84 poll
		1588	Event 20000 202.69 242.91
		1589	Glib 20000 557.01 1689.52
1336	POE 20000 349.67 12317.24 uses POE::Loop::Event	1590	POE 20000 341.54 12086.32 uses POE::Loop::Event
1337		1591
1338	Discussion	1592	Discussion
1339	This benchmark does measure scalability and overall performance of the	1593	This benchmark does measure scalability and overall performance of the
1340	particular event loop.	1594	particular event loop.
1341		1595
1342	EV is again fastest. Since it is using epoll on my system, the setup	1596	EV is again fastest. Since it is using epoll on my system, the setup
1343	time is relatively high, though.	1597	time is relatively high, though.
1344		1598
1345	Perl surprisingly comes second. It is much faster than the C-based event	1599	Perl surprisingly comes second. It is much faster than the C-based event
1346	loops Event and Glib.	1600	loops Event and Glib.
		1601
		1602	IO::Async performs very well when using its epoll backend, and still
		1603	quite good compared to Glib when using its pure perl backend.
1347		1604
1348	Event suffers from high setup time as well (look at its code and you	1605	Event suffers from high setup time as well (look at its code and you
1349	will understand why). Callback invocation also has a high overhead	1606	will understand why). Callback invocation also has a high overhead
1350	compared to the "$_->() for .."-style loop that the Perl event loop	1607	compared to the "$_->() for .."-style loop that the Perl event loop
1351	uses. Event uses select or poll in basically all documented	1608	uses. Event uses select or poll in basically all documented
…		…
1407	THE IO::Lambda BENCHMARK	1664	THE IO::Lambda BENCHMARK
1408	Recently I was told about the benchmark in the IO::Lambda manpage, which	1665	Recently I was told about the benchmark in the IO::Lambda manpage, which
1409	could be misinterpreted to make AnyEvent look bad. In fact, the	1666	could be misinterpreted to make AnyEvent look bad. In fact, the
1410	benchmark simply compares IO::Lambda with POE, and IO::Lambda looks	1667	benchmark simply compares IO::Lambda with POE, and IO::Lambda looks
1411	better (which shouldn't come as a surprise to anybody). As such, the	1668	better (which shouldn't come as a surprise to anybody). As such, the
1412	benchmark is fine, and shows that the AnyEvent backend from IO::Lambda	1669	benchmark is fine, and mostly shows that the AnyEvent backend from
1413	isn't very optimal. But how would AnyEvent compare when used without the	1670	IO::Lambda isn't very optimal. But how would AnyEvent compare when used
1414	extra baggage? To explore this, I wrote the equivalent benchmark for	1671	without the extra baggage? To explore this, I wrote the equivalent
1415	AnyEvent.	1672	benchmark for AnyEvent.
1416		1673
1417	The benchmark itself creates an echo-server, and then, for 500 times,	1674	The benchmark itself creates an echo-server, and then, for 500 times,
1418	connects to the echo server, sends a line, waits for the reply, and then	1675	connects to the echo server, sends a line, waits for the reply, and then
1419	creates the next connection. This is a rather bad benchmark, as it	1676	creates the next connection. This is a rather bad benchmark, as it
1420	doesn't test the efficiency of the framework, but it is a benchmark	1677	doesn't test the efficiency of the framework or much non-blocking I/O,
1421	nevertheless.	1678	but it is a benchmark nevertheless.
1422		1679
1423	name runtime	1680	name runtime
1424	Lambda/select 0.330 sec	1681	Lambda/select 0.330 sec
1425	+ optimized 0.122 sec	1682	+ optimized 0.122 sec
1426	Lambda/AnyEvent 0.327 sec	1683	Lambda/AnyEvent 0.327 sec
…		…
1432		1689
1433	AnyEvent/select/nb 0.085 sec	1690	AnyEvent/select/nb 0.085 sec
1434	AnyEvent/EV/nb 0.068 sec	1691	AnyEvent/EV/nb 0.068 sec
1435	+state machine 0.134 sec	1692	+state machine 0.134 sec
1436		1693
1437	The benchmark is also a bit unfair (my fault) - the IO::Lambda	1694	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
1438	benchmarks actually make blocking connects and use 100% blocking I/O,	1695	benchmarks actually make blocking connects and use 100% blocking I/O,
1439	defeating the purpose of an event-based solution. All of the newly	1696	defeating the purpose of an event-based solution. All of the newly
1440	written AnyEvent benchmarks use 100% non-blocking connects (using	1697	written AnyEvent benchmarks use 100% non-blocking connects (using
1441	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS	1698	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
1442	resolver), so AnyEvent is at a disadvantage here as non-blocking	1699	resolver), so AnyEvent is at a disadvantage here, as non-blocking
1443	connects generally require a lot more bookkeeping and event handling	1700	connects generally require a lot more bookkeeping and event handling
1444	than blocking connects (which involve a single syscall only).	1701	than blocking connects (which involve a single syscall only).
1445		1702
1446	The last AnyEvent benchmark additionally uses AnyEvent::Handle, which	1703	The last AnyEvent benchmark additionally uses AnyEvent::Handle, which
1447	offers similar expressive power as POE and IO::Lambda (using	1704	offers similar expressive power as POE and IO::Lambda, using
1448	conventional Perl syntax), which means both the echo server and the	1705	conventional Perl syntax. This means that both the echo server and the
1449	client are 100% non-blocking w.r.t. I/O, further placing it at a	1706	client are 100% non-blocking, further placing it at a disadvantage.
1450	disadvantage.
1451		1707
1452	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets	1708	As you can see, the AnyEvent + EV combination even beats the
1453	benchmark", while AnyEvent + its pure perl backend easily beats	1709	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
1454	IO::Lambda and POE.	1710	backend easily beats IO::Lambda and POE.
1455		1711
1456	And even the 100% non-blocking version written using the high-level (and	1712	And even the 100% non-blocking version written using the high-level (and
1457	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda, even	1713	slow :) AnyEvent::Handle abstraction beats both POE and IO::Lambda
		1714	higher level ("unoptimised") abstractions by a large margin, even though
1458	thought it does all of DNS, tcp-connect and socket I/O in a non-blocking	1715	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
1459	way.
1460		1716
1461	The two AnyEvent benchmarks can be found as eg/ae0.pl and eg/ae2.pl in	1717	The two AnyEvent benchmarks programs can be found as eg/ae0.pl and
1462	the AnyEvent distribution, the remaining benchmarks are part of the	1718	eg/ae2.pl in the AnyEvent distribution, the remaining benchmarks are
1463	IO::lambda distribution and were used without any changes.	1719	part of the IO::Lambda distribution and were used without any changes.
1464		1720
1465	SIGNALS	1721	SIGNALS
1466	AnyEvent currently installs handlers for these signals:	1722	AnyEvent currently installs handlers for these signals:
1467		1723
1468	SIGCHLD	1724	SIGCHLD
1469	A handler for "SIGCHLD" is installed by AnyEvent's child watcher	1725	A handler for "SIGCHLD" is installed by AnyEvent's child watcher
1470	emulation for event loops that do not support them natively. Also,	1726	emulation for event loops that do not support them natively. Also,
1471	some event loops install a similar handler.	1727	some event loops install a similar handler.
		1728
		1729	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE,
		1730	then AnyEvent will reset it to default, to avoid losing child exit
		1731	statuses.
1472		1732
1473	SIGPIPE	1733	SIGPIPE
1474	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is	1734	A no-op handler is installed for "SIGPIPE" when $SIG{PIPE} is
1475	"undef" when AnyEvent gets loaded.	1735	"undef" when AnyEvent gets loaded.
1476		1736
…		…
1484	it is that this way, the handler will be restored to defaults on	1744	it is that this way, the handler will be restored to defaults on
1485	exec.	1745	exec.
1486		1746
1487	Feel free to install your own handler, or reset it to defaults.	1747	Feel free to install your own handler, or reset it to defaults.
1488		1748
		1749	RECOMMENDED/OPTIONAL MODULES
		1750	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		1751	it's built-in modules) are required to use it.
		1752
		1753	That does not mean that AnyEvent won't take advantage of some additional
		1754	modules if they are installed.
		1755
		1756	This section explains which additional modules will be used, and how
		1757	they affect AnyEvent's operation.
		1758
		1759	Async::Interrupt
		1760	This slightly arcane module is used to implement fast signal
		1761	handling: To my knowledge, there is no way to do completely
		1762	race-free and quick signal handling in pure perl. To ensure that
		1763	signals still get delivered, AnyEvent will start an interval timer
		1764	to wake up perl (and catch the signals) with some delay (default is
		1765	10 seconds, look for $AnyEvent::MAX_SIGNAL_LATENCY).
		1766
		1767	If this module is available, then it will be used to implement
		1768	signal catching, which means that signals will not be delayed, and
		1769	the event loop will not be interrupted regularly, which is more
		1770	efficient (and good for battery life on laptops).
		1771
		1772	This affects not just the pure-perl event loop, but also other event
		1773	loops that have no signal handling on their own (e.g. Glib, Tk, Qt).
		1774
		1775	Some event loops (POE, Event, Event::Lib) offer signal watchers
		1776	natively, and either employ their own workarounds (POE) or use
		1777	AnyEvent's workaround (using $AnyEvent::MAX_SIGNAL_LATENCY).
		1778	Installing Async::Interrupt does nothing for those backends.
		1779
		1780	EV This module isn't really "optional", as it is simply one of the
		1781	backend event loops that AnyEvent can use. However, it is simply the
		1782	best event loop available in terms of features, speed and stability:
		1783	It supports the AnyEvent API optimally, implements all the watcher
		1784	types in XS, does automatic timer adjustments even when no monotonic
		1785	clock is available, can take avdantage of advanced kernel interfaces
		1786	such as "epoll" and "kqueue", and is the fastest backend by far.
		1787	You can even embed Glib/Gtk2 in it (or vice versa, see EV::Glib and
		1788	Glib::EV).
		1789
		1790	If you only use backends that rely on another event loop (e.g.
		1791	"Tk"), then this module will do nothing for you.
		1792
		1793	Guard
		1794	The guard module, when used, will be used to implement
		1795	"AnyEvent::Util::guard". This speeds up guards considerably (and
		1796	uses a lot less memory), but otherwise doesn't affect guard
		1797	operation much. It is purely used for performance.
		1798
		1799	JSON and JSON::XS
		1800	One of these modules is required when you want to read or write JSON
		1801	data via AnyEvent::Handle. JSON is also written in pure-perl, but
		1802	can take advantage of the ultra-high-speed JSON::XS module when it
		1803	is installed.
		1804
		1805	Net::SSLeay
		1806	Implementing TLS/SSL in Perl is certainly interesting, but not very
		1807	worthwhile: If this module is installed, then AnyEvent::Handle (with
		1808	the help of AnyEvent::TLS), gains the ability to do TLS/SSL.
		1809
		1810	Time::HiRes
		1811	This module is part of perl since release 5.008. It will be used
		1812	when the chosen event library does not come with a timing source on
		1813	it's own. The pure-perl event loop (AnyEvent::Impl::Perl) will
		1814	additionally use it to try to use a monotonic clock for timing
		1815	stability.
		1816
1489	FORK	1817	FORK
1490	Most event libraries are not fork-safe. The ones who are usually are	1818	Most event libraries are not fork-safe. The ones who are usually are
1491	because they rely on inefficient but fork-safe "select" or "poll" calls.	1819	because they rely on inefficient but fork-safe "select" or "poll" calls
1492	Only EV is fully fork-aware.	1820	- higher performance APIs such as BSD's kqueue or the dreaded Linux
		1821	epoll are usually badly thought-out hacks that are incompatible with
		1822	fork in one way or another. Only EV is fully fork-aware and ensures that
		1823	you continue event-processing in both parent and child (or both, if you
		1824	know what you are doing).
		1825
		1826	This means that, in general, you cannot fork and do event processing in
		1827	the child if the event library was initialised before the fork (which
		1828	usually happens when the first AnyEvent watcher is created, or the
		1829	library is loaded).
1493		1830
1494	If you have to fork, you must either do so before creating your first	1831	If you have to fork, you must either do so before creating your first
1495	watcher OR you must not use AnyEvent at all in the child.	1832	watcher OR you must not use AnyEvent at all in the child OR you must do
		1833	something completely out of the scope of AnyEvent.
		1834
		1835	The problem of doing event processing in the parent and the child is
		1836	much more complicated: even for backends that are fork-aware or
		1837	fork-safe, their behaviour is not usually what you want: fork clones all
		1838	watchers, that means all timers, I/O watchers etc. are active in both
		1839	parent and child, which is almost never what you want. USing "exec" to
		1840	start worker children from some kind of manage rprocess is usually
		1841	preferred, because it is much easier and cleaner, at the expense of
		1842	having to have another binary.
1496		1843
1497	SECURITY CONSIDERATIONS	1844	SECURITY CONSIDERATIONS
1498	AnyEvent can be forced to load any event model via	1845	AnyEvent can be forced to load any event model via
1499	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used	1846	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used
1500	to execute arbitrary code or directly gain access, it can easily be used	1847	to execute arbitrary code or directly gain access, it can easily be used
…		…
1512	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1859	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1513	be used to probe what backend is used and gain other information (which	1860	be used to probe what backend is used and gain other information (which
1514	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),	1861	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL),
1515	and $ENV{PERL_ANYEVENT_STRICT}.	1862	and $ENV{PERL_ANYEVENT_STRICT}.
1516		1863
		1864	Note that AnyEvent will remove all environment variables starting with
		1865	"PERL_ANYEVENT_" from %ENV when it is loaded while taint mode is
		1866	enabled.
		1867
1517	BUGS	1868	BUGS
1518	Perl 5.8 has numerous memleaks that sometimes hit this module and are	1869	Perl 5.8 has numerous memleaks that sometimes hit this module and are
1519	hard to work around. If you suffer from memleaks, first upgrade to Perl	1870	hard to work around. If you suffer from memleaks, first upgrade to Perl
1520	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other	1871	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
1521	annoying memleaks, such as leaking on "map" and "grep" but it is usually	1872	annoying memleaks, such as leaking on "map" and "grep" but it is usually
…		…
1527	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,	1878	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
1528	Event::Lib, Qt, POE.	1879	Event::Lib, Qt, POE.
1529		1880
1530	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,	1881	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
1531	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,	1882	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
1532	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1883	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE,
		1884	AnyEvent::Impl::IOAsync, Anyevent::Impl::Irssi.
1533		1885
1534	Non-blocking file handles, sockets, TCP clients and servers:	1886	Non-blocking file handles, sockets, TCP clients and servers:
1535	AnyEvent::Handle, AnyEvent::Socket.	1887	AnyEvent::Handle, AnyEvent::Socket, AnyEvent::TLS.
1536		1888
1537	Asynchronous DNS: AnyEvent::DNS.	1889	Asynchronous DNS: AnyEvent::DNS.
1538		1890
1539	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,	1891	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
1540		1892
1541	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.	1893	Nontrivial usage examples: AnyEvent::GPSD, AnyEvent::XMPP,
		1894	AnyEvent::HTTP.
1542		1895
1543	AUTHOR	1896	AUTHOR
1544	Marc Lehmann <schmorp@schmorp.de>	1897	Marc Lehmann <schmorp@schmorp.de>
1545	http://home.schmorp.de/	1898	http://home.schmorp.de/
1546		1899

Diff Legend

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

Comparing AnyEvent/README (file contents): Revision 1.40 by root, Tue Jun 23 23:37:32 2009 UTC vs. Revision 1.62 by root, Sun Jun 6 10:13:57 2010 UTC

Diff Legend

Comparing AnyEvent/README (file contents):
Revision 1.40 by root, Tue Jun 23 23:37:32 2009 UTC vs.
Revision 1.62 by root, Sun Jun 6 10:13:57 2010 UTC