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Comparing AnyEvent/README (file contents):
Revision 1.19 by root, Mon Apr 28 08:02:14 2008 UTC vs.
Revision 1.27 by root, Sun Jun 22 12:17:47 2008 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, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE -	4	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event
5	various supported event loops	5	loops
6		6
7	SYNOPSIS	7	SYNOPSIS
8	use AnyEvent;	8	use AnyEvent;
9		9
10	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	10	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {
14	my $w = AnyEvent->timer (after => $seconds, cb => sub {	14	my $w = AnyEvent->timer (after => $seconds, cb => sub {
15	...	15	...
16	});	16	});
17		17
18	my $w = AnyEvent->condvar; # stores whether a condition was flagged	18	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		19	$w->send; # wake up current and all future recv's
19	$w->wait; # enters "main loop" till $condvar gets ->broadcast	20	$w->recv; # enters "main loop" till $condvar gets ->send
20	$w->broadcast; # wake up current and all future wait's	21
		22	INTRODUCTION/TUTORIAL
		23	This manpage is mainly a reference manual. If you are interested in a
		24	tutorial or some gentle introduction, have a look at the AnyEvent::Intro
		25	manpage.
21		26
22	WHY YOU SHOULD USE THIS MODULE (OR NOT)	27	WHY YOU SHOULD USE THIS MODULE (OR NOT)
23	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	28	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
24	nowadays. So what is different about AnyEvent?	29	nowadays. So what is different about AnyEvent?
25		30
…		…
46	that isn't itself. What's worse, all the potential users of your module	51	that isn't itself. What's worse, all the potential users of your module
47	are also forced to use the same event loop you use.	52	are also forced to use the same event loop you use.
48		53
49	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	54	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
50	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	55	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
51	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if your	56	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if your
52	module uses one of those, every user of your module has to use it, too.	57	module uses one of those, every user of your module has to use it, too.
53	But if your module uses AnyEvent, it works transparently with all event	58	But if your module uses AnyEvent, it works transparently with all event
54	models it supports (including stuff like POE and IO::Async, as long as	59	models it supports (including stuff like POE and IO::Async, as long as
55	those use one of the supported event loops. It is trivial to add new	60	those use one of the supported event loops. It is trivial to add new
56	event loops to AnyEvent, too, so it is future-proof).	61	event loops to AnyEvent, too, so it is future-proof).
57		62
58	In addition to being free of having to use *the one and only true event	63	In addition to being free of having to use *the one and only true event
59	model*, AnyEvent also is free of bloat and policy: with POE or similar	64	model*, AnyEvent also is free of bloat and policy: with POE or similar
60	modules, you get an enourmous amount of code and strict rules you have	65	modules, you get an enormous amount of code and strict rules you have to
61	to follow. AnyEvent, on the other hand, is lean and up to the point, by	66	follow. AnyEvent, on the other hand, is lean and up to the point, by
62	only offering the functionality that is necessary, in as thin as a	67	only offering the functionality that is necessary, in as thin as a
63	wrapper as technically possible.	68	wrapper as technically possible.
64		69
		70	Of course, AnyEvent comes with a big (and fully optional!) toolbox of
		71	useful functionality, such as an asynchronous DNS resolver, 100%
		72	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		73	such as Windows) and lots of real-world knowledge and workarounds for
		74	platform bugs and differences.
		75
65	Of course, if you want lots of policy (this can arguably be somewhat	76	Now, if you do want lots of policy (this can arguably be somewhat
66	useful) and you want to force your users to use the one and only event	77	useful) and you want to force your users to use the one and only event
67	model, you should not use this module.	78	model, you should not use this module.
68		79
69	DESCRIPTION	80	DESCRIPTION
70	AnyEvent provides an identical interface to multiple event loops. This	81	AnyEvent provides an identical interface to multiple event loops. This
…		…
75	The interface itself is vaguely similar, but not identical to the Event	86	The interface itself is vaguely similar, but not identical to the Event
76	module.	87	module.
77		88
78	During the first call of any watcher-creation method, the module tries	89	During the first call of any watcher-creation method, the module tries
79	to detect the currently loaded event loop by probing whether one of the	90	to detect the currently loaded event loop by probing whether one of the
80	following modules is already loaded: Coro::EV, Coro::Event, EV, Event,	91	following modules is already loaded: EV, Event, Glib,
81	Glib, AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found	92	AnyEvent::Impl::Perl, Tk, Event::Lib, Qt, POE. The first one found is
82	is used. If none are found, the module tries to load these modules	93	used. If none are found, the module tries to load these modules
83	(excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should	94	(excluding Tk, Event::Lib, Qt and POE as the pure perl adaptor should
84	always succeed) in the order given. The first one that can be	95	always succeed) in the order given. The first one that can be
85	successfully loaded will be used. If, after this, still none could be	96	successfully loaded will be used. If, after this, still none could be
86	found, AnyEvent will fall back to a pure-perl event loop, which is not	97	found, AnyEvent will fall back to a pure-perl event loop, which is not
87	very efficient, but should work everywhere.	98	very efficient, but should work everywhere.
…		…
99	starts using it, all bets are off. Maybe you should tell their authors	110	starts using it, all bets are off. Maybe you should tell their authors
100	to use AnyEvent so their modules work together with others seamlessly...	111	to use AnyEvent so their modules work together with others seamlessly...
101		112
102	The pure-perl implementation of AnyEvent is called	113	The pure-perl implementation of AnyEvent is called
103	"AnyEvent::Impl::Perl". Like other event modules you can load it	114	"AnyEvent::Impl::Perl". Like other event modules you can load it
104	explicitly.	115	explicitly and enjoy the high availability of that event loop :)
105		116
106	WATCHERS	117	WATCHERS
107	AnyEvent has the central concept of a watcher, which is an object that	118	AnyEvent has the central concept of a watcher, which is an object that
108	stores relevant data for each kind of event you are waiting for, such as	119	stores relevant data for each kind of event you are waiting for, such as
109	the callback to call, the filehandle to watch, etc.	120	the callback to call, the file handle to watch, etc.
110		121
111	These watchers are normal Perl objects with normal Perl lifetime. After	122	These watchers are normal Perl objects with normal Perl lifetime. After
112	creating a watcher it will immediately "watch" for events and invoke the	123	creating a watcher it will immediately "watch" for events and invoke the
113	callback when the event occurs (of course, only when the event model is	124	callback when the event occurs (of course, only when the event model is
114	in control).	125	in control).
…		…
122	Many watchers either are used with "recursion" (repeating timers for	133	Many watchers either are used with "recursion" (repeating timers for
123	example), or need to refer to their watcher object in other ways.	134	example), or need to refer to their watcher object in other ways.
124		135
125	An any way to achieve that is this pattern:	136	An any way to achieve that is this pattern:
126		137
127	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	138	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
128	# you can use $w here, for example to undef it	139	# you can use $w here, for example to undef it
129	undef $w;	140	undef $w;
130	});	141	});
131		142
132	Note that "my $w; $w =" combination. This is necessary because in Perl,	143	Note that "my $w; $w =" combination. This is necessary because in Perl,
133	my variables are only visible after the statement in which they are	144	my variables are only visible after the statement in which they are
134	declared.	145	declared.
135		146
…		…
220	on wallclock time) timers.	231	on wallclock time) timers.
221		232
222	AnyEvent always prefers relative timers, if available, matching the	233	AnyEvent always prefers relative timers, if available, matching the
223	AnyEvent API.	234	AnyEvent API.
224		235
		236	AnyEvent has two additional methods that return the "current time":
		237
		238	AnyEvent->time
		239	This returns the "current wallclock time" as a fractional number of
		240	seconds since the Epoch (the same thing as "time" or
		241	"Time::HiRes::time" return, and the result is guaranteed to be
		242	compatible with those).
		243
		244	It progresses independently of any event loop processing, i.e. each
		245	call will check the system clock, which usually gets updated
		246	frequently.
		247
		248	AnyEvent->now
		249	This also returns the "current wallclock time", but unlike "time",
		250	above, this value might change only once per event loop iteration,
		251	depending on the event loop (most return the same time as "time",
		252	above). This is the time that AnyEvent's timers get scheduled
		253	against.
		254
		255	*In almost all cases (in all cases if you don't care), this is the
		256	function to call when you want to know the current time.*
		257
		258	This function is also often faster then "AnyEvent->time", and thus
		259	the preferred method if you want some timestamp (for example,
		260	AnyEvent::Handle uses this to update it's activity timeouts).
		261
		262	The rest of this section is only of relevance if you try to be very
		263	exact with your timing, you can skip it without bad conscience.
		264
		265	For a practical example of when these times differ, consider
		266	Event::Lib and EV and the following set-up:
		267
		268	The event loop is running and has just invoked one of your callback
		269	at time=500 (assume no other callbacks delay processing). In your
		270	callback, you wait a second by executing "sleep 1" (blocking the
		271	process for a second) and then (at time=501) you create a relative
		272	timer that fires after three seconds.
		273
		274	With Event::Lib, "AnyEvent->time" and "AnyEvent->now" will both
		275	return 501, because that is the current time, and the timer will be
		276	scheduled to fire at time=504 (501 + 3).
		277
		278	With EV, "AnyEvent->time" returns 501 (as that is the current time),
		279	but "AnyEvent->now" returns 500, as that is the time the last event
		280	processing phase started. With EV, your timer gets scheduled to run
		281	at time=503 (500 + 3).
		282
		283	In one sense, Event::Lib is more exact, as it uses the current time
		284	regardless of any delays introduced by event processing. However,
		285	most callbacks do not expect large delays in processing, so this
		286	causes a higher drift (and a lot more system calls to get the
		287	current time).
		288
		289	In another sense, EV is more exact, as your timer will be scheduled
		290	at the same time, regardless of how long event processing actually
		291	took.
		292
		293	In either case, if you care (and in most cases, you don't), then you
		294	can get whatever behaviour you want with any event loop, by taking
		295	the difference between "AnyEvent->time" and "AnyEvent->now" into
		296	account.
		297
225	SIGNAL WATCHERS	298	SIGNAL WATCHERS
226	You can watch for signals using a signal watcher, "signal" is the signal	299	You can watch for signals using a signal watcher, "signal" is the signal
227	name without any "SIG" prefix, "cb" is the Perl callback to be invoked	300	name without any "SIG" prefix, "cb" is the Perl callback to be invoked
228	whenever a signal occurs.	301	whenever a signal occurs.
229		302
230	Although the callback might get passed parameters, their value and	303	Although the callback might get passed parameters, their value and
231	presence is undefined and you cannot rely on them. Portable AnyEvent	304	presence is undefined and you cannot rely on them. Portable AnyEvent
232	callbacks cannot use arguments passed to signal watcher callbacks.	305	callbacks cannot use arguments passed to signal watcher callbacks.
233		306
234	Multiple signal occurances can be clumped together into one callback	307	Multiple signal occurrences can be clumped together into one callback
235	invocation, and callback invocation will be synchronous. synchronous	308	invocation, and callback invocation will be synchronous. Synchronous
236	means that it might take a while until the signal gets handled by the	309	means that it might take a while until the signal gets handled by the
237	process, but it is guarenteed not to interrupt any other callbacks.	310	process, but it is guaranteed not to interrupt any other callbacks.
238		311
239	The main advantage of using these watchers is that you can share a	312	The main advantage of using these watchers is that you can share a
240	signal between multiple watchers.	313	signal between multiple watchers.
241		314
242	This watcher might use %SIG, so programs overwriting those signals	315	This watcher might use %SIG, so programs overwriting those signals
…		…
269	an AnyEvent program, you have to create at least one watcher before	342	an AnyEvent program, you have to create at least one watcher before
270	you "fork" the child (alternatively, you can call "AnyEvent::detect").	343	you "fork" the child (alternatively, you can call "AnyEvent::detect").
271		344
272	Example: fork a process and wait for it	345	Example: fork a process and wait for it
273		346
274	my $done = AnyEvent->condvar;	347	my $done = AnyEvent->condvar;
275		348
276	AnyEvent::detect; # force event module to be initialised
277
278	my $pid = fork or exit 5;	349	my $pid = fork or exit 5;
279		350
280	my $w = AnyEvent->child (	351	my $w = AnyEvent->child (
281	pid => $pid,	352	pid => $pid,
282	cb => sub {	353	cb => sub {
283	my ($pid, $status) = @_;	354	my ($pid, $status) = @_;
284	warn "pid $pid exited with status $status";	355	warn "pid $pid exited with status $status";
285	$done->broadcast;	356	$done->send;
286	},	357	},
287	);	358	);
288		359
289	# do something else, then wait for process exit	360	# do something else, then wait for process exit
290	$done->wait;	361	$done->recv;
291		362
292	CONDITION VARIABLES	363	CONDITION VARIABLES
		364	If you are familiar with some event loops you will know that all of them
		365	require you to run some blocking "loop", "run" or similar function that
		366	will actively watch for new events and call your callbacks.
		367
		368	AnyEvent is different, it expects somebody else to run the event loop
		369	and will only block when necessary (usually when told by the user).
		370
		371	The instrument to do that is called a "condition variable", so called
		372	because they represent a condition that must become true.
		373
293	Condition variables can be created by calling the "AnyEvent->condvar"	374	Condition variables can be created by calling the "AnyEvent->condvar"
294	method without any arguments.	375	method, usually without arguments. The only argument pair allowed is
		376	"cb", which specifies a callback to be called when the condition
		377	variable becomes true.
295		378
296	A condition variable waits for a condition - precisely that the	379	After creation, the condition variable is "false" until it becomes
297	"->broadcast" method has been called.	380	"true" by calling the "send" method (or calling the condition variable
		381	as if it were a callback, read about the caveats in the description for
		382	the "->send" method).
298		383
299	They are very useful to signal that a condition has been fulfilled, for	384	Condition variables are similar to callbacks, except that you can
		385	optionally wait for them. They can also be called merge points - points
		386	in time where multiple outstanding events have been processed. And yet
		387	another way to call them is transactions - each condition variable can
		388	be used to represent a transaction, which finishes at some point and
		389	delivers a result.
		390
		391	Condition variables are very useful to signal that something has
300	example, if you write a module that does asynchronous http requests,	392	finished, for example, if you write a module that does asynchronous http
301	then a condition variable would be the ideal candidate to signal the	393	requests, then a condition variable would be the ideal candidate to
302	availability of results.	394	signal the availability of results. The user can either act when the
		395	callback is called or can synchronously "->recv" for the results.
303		396
304	You can also use condition variables to block your main program until an	397	You can also use them to simulate traditional event loops - for example,
305	event occurs - for example, you could "->wait" in your main program	398	you can block your main program until an event occurs - for example, you
306	until the user clicks the Quit button in your app, which would	399	could "->recv" in your main program until the user clicks the Quit
307	"->broadcast" the "quit" event.	400	button of your app, which would "->send" the "quit" event.
308		401
309	Note that condition variables recurse into the event loop - if you have	402	Note that condition variables recurse into the event loop - if you have
310	two pirces of code that call "->wait" in a round-robbin fashion, you	403	two pieces of code that call "->recv" in a round-robin fashion, you
311	lose. Therefore, condition variables are good to export to your caller,	404	lose. Therefore, condition variables are good to export to your caller,
312	but you should avoid making a blocking wait yourself, at least in	405	but you should avoid making a blocking wait yourself, at least in
313	callbacks, as this asks for trouble.	406	callbacks, as this asks for trouble.
314		407
315	This object has two methods:	408	Condition variables are represented by hash refs in perl, and the keys
		409	used by AnyEvent itself are all named "_ae_XXX" to make subclassing easy
		410	(it is often useful to build your own transaction class on top of
		411	AnyEvent). To subclass, use "AnyEvent::CondVar" as base class and call
		412	it's "new" method in your own "new" method.
316		413
317	$cv->wait	414	There are two "sides" to a condition variable - the "producer side"
		415	which eventually calls "-> send", and the "consumer side", which waits
		416	for the send to occur.
		417
		418	Example: wait for a timer.
		419
		420	# wait till the result is ready
		421	my $result_ready = AnyEvent->condvar;
		422
		423	# do something such as adding a timer
		424	# or socket watcher the calls $result_ready->send
		425	# when the "result" is ready.
		426	# in this case, we simply use a timer:
		427	my $w = AnyEvent->timer (
		428	after => 1,
		429	cb => sub { $result_ready->send },
		430	);
		431
		432	# this "blocks" (while handling events) till the callback
		433	# calls send
		434	$result_ready->recv;
		435
		436	Example: wait for a timer, but take advantage of the fact that condition
		437	variables are also code references.
		438
		439	my $done = AnyEvent->condvar;
		440	my $delay = AnyEvent->timer (after => 5, cb => $done);
		441	$done->recv;
		442
		443	METHODS FOR PRODUCERS
		444	These methods should only be used by the producing side, i.e. the
		445	code/module that eventually sends the signal. Note that it is also the
		446	producer side which creates the condvar in most cases, but it isn't
		447	uncommon for the consumer to create it as well.
		448
		449	$cv->send (...)
		450	Flag the condition as ready - a running "->recv" and all further
		451	calls to "recv" will (eventually) return after this method has been
		452	called. If nobody is waiting the send will be remembered.
		453
		454	If a callback has been set on the condition variable, it is called
		455	immediately from within send.
		456
		457	Any arguments passed to the "send" call will be returned by all
		458	future "->recv" calls.
		459
		460	Condition variables are overloaded so one can call them directly (as
		461	a code reference). Calling them directly is the same as calling
		462	"send". Note, however, that many C-based event loops do not handle
		463	overloading, so as tempting as it may be, passing a condition
		464	variable instead of a callback does not work. Both the pure perl and
		465	EV loops support overloading, however, as well as all functions that
		466	use perl to invoke a callback (as in AnyEvent::Socket and
		467	AnyEvent::DNS for example).
		468
		469	$cv->croak ($error)
		470	Similar to send, but causes all call's to "->recv" to invoke
		471	"Carp::croak" with the given error message/object/scalar.
		472
		473	This can be used to signal any errors to the condition variable
		474	user/consumer.
		475
		476	$cv->begin ([group callback])
		477	$cv->end
		478	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		479
		480	These two methods can be used to combine many transactions/events
		481	into one. For example, a function that pings many hosts in parallel
		482	might want to use a condition variable for the whole process.
		483
		484	Every call to "->begin" will increment a counter, and every call to
		485	"->end" will decrement it. If the counter reaches 0 in "->end", the
		486	(last) callback passed to "begin" will be executed. That callback is
		487	supposed to call "->send", but that is not required. If no
		488	callback was set, "send" will be called without any arguments.
		489
		490	Let's clarify this with the ping example:
		491
		492	my $cv = AnyEvent->condvar;
		493
		494	my %result;
		495	$cv->begin (sub { $cv->send (\%result) });
		496
		497	for my $host (@list_of_hosts) {
		498	$cv->begin;
		499	ping_host_then_call_callback $host, sub {
		500	$result{$host} = ...;
		501	$cv->end;
		502	};
		503	}
		504
		505	$cv->end;
		506
		507	This code fragment supposedly pings a number of hosts and calls
		508	"send" after results for all then have have been gathered - in any
		509	order. To achieve this, the code issues a call to "begin" when it
		510	starts each ping request and calls "end" when it has received some
		511	result for it. Since "begin" and "end" only maintain a counter, the
		512	order in which results arrive is not relevant.
		513
		514	There is an additional bracketing call to "begin" and "end" outside
		515	the loop, which serves two important purposes: first, it sets the
		516	callback to be called once the counter reaches 0, and second, it
		517	ensures that "send" is called even when "no" hosts are being pinged
		518	(the loop doesn't execute once).
		519
		520	This is the general pattern when you "fan out" into multiple
		521	subrequests: use an outer "begin"/"end" pair to set the callback and
		522	ensure "end" is called at least once, and then, for each subrequest
		523	you start, call "begin" and for each subrequest you finish, call
		524	"end".
		525
		526	METHODS FOR CONSUMERS
		527	These methods should only be used by the consuming side, i.e. the code
		528	awaits the condition.
		529
		530	$cv->recv
318	Wait (blocking if necessary) until the "->broadcast" method has been	531	Wait (blocking if necessary) until the "->send" or "->croak" methods
319	called on c<$cv>, while servicing other watchers normally.	532	have been called on c<$cv>, while servicing other watchers normally.
320		533
321	You can only wait once on a condition - additional calls will return	534	You can only wait once on a condition - additional calls are valid
322	immediately.	535	but will return immediately.
		536
		537	If an error condition has been set by calling "->croak", then this
		538	function will call "croak".
		539
		540	In list context, all parameters passed to "send" will be returned,
		541	in scalar context only the first one will be returned.
323		542
324	Not all event models support a blocking wait - some die in that case	543	Not all event models support a blocking wait - some die in that case
325	(programs might want to do that to stay interactive), so *if you are	544	(programs might want to do that to stay interactive), so *if you are
326	using this from a module, never require a blocking wait*, but let	545	using this from a module, never require a blocking wait*, but let
327	the caller decide whether the call will block or not (for example,	546	the caller decide whether the call will block or not (for example,
328	by coupling condition variables with some kind of request results	547	by coupling condition variables with some kind of request results
329	and supporting callbacks so the caller knows that getting the result	548	and supporting callbacks so the caller knows that getting the result
330	will not block, while still suppporting blocking waits if the caller	549	will not block, while still supporting blocking waits if the caller
331	so desires).	550	so desires).
332		551
333	Another reason never to "->wait" in a module is that you cannot	552	Another reason never to "->recv" in a module is that you cannot
334	sensibly have two "->wait"'s in parallel, as that would require	553	sensibly have two "->recv"'s in parallel, as that would require
335	multiple interpreters or coroutines/threads, none of which	554	multiple interpreters or coroutines/threads, none of which
336	"AnyEvent" can supply (the coroutine-aware backends	555	"AnyEvent" can supply.
337	AnyEvent::Impl::CoroEV and AnyEvent::Impl::CoroEvent explicitly
338	support concurrent "->wait"'s from different coroutines, however).
339		556
340	$cv->broadcast	557	The Coro module, however, can and does supply coroutines and, in
341	Flag the condition as ready - a running "->wait" and all further	558	fact, Coro::AnyEvent replaces AnyEvent's condvars by coroutine-safe
342	calls to "wait" will (eventually) return after this method has been	559	versions and also integrates coroutines into AnyEvent, making
343	called. If nobody is waiting the broadcast will be remembered..	560	blocking "->recv" calls perfectly safe as long as they are done from
		561	another coroutine (one that doesn't run the event loop).
344		562
345	Example:	563	You can ensure that "-recv" never blocks by setting a callback and
		564	only calling "->recv" from within that callback (or at a later
		565	time). This will work even when the event loop does not support
		566	blocking waits otherwise.
346		567
347	# wait till the result is ready	568	$bool = $cv->ready
348	my $result_ready = AnyEvent->condvar;	569	Returns true when the condition is "true", i.e. whether "send" or
		570	"croak" have been called.
349		571
350	# do something such as adding a timer	572	$cb = $cv->cb ([new callback])
351	# or socket watcher the calls $result_ready->broadcast	573	This is a mutator function that returns the callback set and
352	# when the "result" is ready.	574	optionally replaces it before doing so.
353	# in this case, we simply use a timer:
354	my $w = AnyEvent->timer (
355	after => 1,
356	cb => sub { $result_ready->broadcast },
357	);
358		575
359	# this "blocks" (while handling events) till the watcher	576	The callback will be called when the condition becomes "true", i.e.
360	# calls broadcast	577	when "send" or "croak" are called, with the only argument being the
361	$result_ready->wait;	578	condition variable itself. Calling "recv" inside the callback or at
		579	any later time is guaranteed not to block.
362		580
363	GLOBAL VARIABLES AND FUNCTIONS	581	GLOBAL VARIABLES AND FUNCTIONS
364	$AnyEvent::MODEL	582	$AnyEvent::MODEL
365	Contains "undef" until the first watcher is being created. Then it	583	Contains "undef" until the first watcher is being created. Then it
366	contains the event model that is being used, which is the name of	584	contains the event model that is being used, which is the name of
…		…
368	the "AnyEvent::Impl:xxx" modules, but can be any other class in the	586	the "AnyEvent::Impl:xxx" modules, but can be any other class in the
369	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).	587	case AnyEvent has been extended at runtime (e.g. in rxvt-unicode).
370		588
371	The known classes so far are:	589	The known classes so far are:
372		590
373	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
374	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
375	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	591	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
376	AnyEvent::Impl::Event based on Event, second best choice.	592	AnyEvent::Impl::Event based on Event, second best choice.
		593	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
377	AnyEvent::Impl::Glib based on Glib, third-best choice.	594	AnyEvent::Impl::Glib based on Glib, third-best choice.
378	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
379	AnyEvent::Impl::Tk based on Tk, very bad choice.	595	AnyEvent::Impl::Tk based on Tk, very bad choice.
380	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	596	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
381	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	597	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
382	AnyEvent::Impl::POE based on POE, not generic enough for full support.	598	AnyEvent::Impl::POE based on POE, not generic enough for full support.
383		599
…		…
395	Returns $AnyEvent::MODEL, forcing autodetection of the event model	611	Returns $AnyEvent::MODEL, forcing autodetection of the event model
396	if necessary. You should only call this function right before you	612	if necessary. You should only call this function right before you
397	would have created an AnyEvent watcher anyway, that is, as late as	613	would have created an AnyEvent watcher anyway, that is, as late as
398	possible at runtime.	614	possible at runtime.
399		615
		616	$guard = AnyEvent::post_detect { BLOCK }
		617	Arranges for the code block to be executed as soon as the event
		618	model is autodetected (or immediately if this has already happened).
		619
		620	If called in scalar or list context, then it creates and returns an
		621	object that automatically removes the callback again when it is
		622	destroyed. See Coro::BDB for a case where this is useful.
		623
		624	@AnyEvent::post_detect
		625	If there are any code references in this array (you can "push" to it
		626	before or after loading AnyEvent), then they will called directly
		627	after the event loop has been chosen.
		628
		629	You should check $AnyEvent::MODEL before adding to this array,
		630	though: if it contains a true value then the event loop has already
		631	been detected, and the array will be ignored.
		632
		633	Best use "AnyEvent::post_detect { BLOCK }" instead.
		634
400	WHAT TO DO IN A MODULE	635	WHAT TO DO IN A MODULE
401	As a module author, you should "use AnyEvent" and call AnyEvent methods	636	As a module author, you should "use AnyEvent" and call AnyEvent methods
402	freely, but you should not load a specific event module or rely on it.	637	freely, but you should not load a specific event module or rely on it.
403		638
404	Be careful when you create watchers in the module body - AnyEvent will	639	Be careful when you create watchers in the module body - AnyEvent will
405	decide which event module to use as soon as the first method is called,	640	decide which event module to use as soon as the first method is called,
406	so by calling AnyEvent in your module body you force the user of your	641	so by calling AnyEvent in your module body you force the user of your
407	module to load the event module first.	642	module to load the event module first.
408		643
409	Never call "->wait" on a condition variable unless you know that the	644	Never call "->recv" on a condition variable unless you know that the
410	"->broadcast" method has been called on it already. This is because it	645	"->send" method has been called on it already. This is because it will
411	will stall the whole program, and the whole point of using events is to	646	stall the whole program, and the whole point of using events is to stay
412	stay interactive.	647	interactive.
413		648
414	It is fine, however, to call "->wait" when the user of your module	649	It is fine, however, to call "->recv" when the user of your module
415	requests it (i.e. if you create a http request object ad have a method	650	requests it (i.e. if you create a http request object ad have a method
416	called "results" that returns the results, it should call "->wait"	651	called "results" that returns the results, it should call "->recv"
417	freely, as the user of your module knows what she is doing. always).	652	freely, as the user of your module knows what she is doing. always).
418		653
419	WHAT TO DO IN THE MAIN PROGRAM	654	WHAT TO DO IN THE MAIN PROGRAM
420	There will always be a single main program - the only place that should	655	There will always be a single main program - the only place that should
421	dictate which event model to use.	656	dictate which event model to use.
…		…
423	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	658	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
424	do anything special (it does not need to be event-based) and let	659	do anything special (it does not need to be event-based) and let
425	AnyEvent decide which implementation to chose if some module relies on	660	AnyEvent decide which implementation to chose if some module relies on
426	it.	661	it.
427		662
428	If the main program relies on a specific event model. For example, in	663	If the main program relies on a specific event model - for example, in
429	Gtk2 programs you have to rely on the Glib module. You should load the	664	Gtk2 programs you have to rely on the Glib module - you should load the
430	event module before loading AnyEvent or any module that uses it:	665	event module before loading AnyEvent or any module that uses it:
431	generally speaking, you should load it as early as possible. The reason	666	generally speaking, you should load it as early as possible. The reason
432	is that modules might create watchers when they are loaded, and AnyEvent	667	is that modules might create watchers when they are loaded, and AnyEvent
433	will decide on the event model to use as soon as it creates watchers,	668	will decide on the event model to use as soon as it creates watchers,
434	and it might chose the wrong one unless you load the correct one	669	and it might chose the wrong one unless you load the correct one
435	yourself.	670	yourself.
436		671
437	You can chose to use a rather inefficient pure-perl implementation by	672	You can chose to use a pure-perl implementation by loading the
438	loading the "AnyEvent::Impl::Perl" module, which gives you similar	673	"AnyEvent::Impl::Perl" module, which gives you similar behaviour
439	behaviour everywhere, but letting AnyEvent chose is generally better.	674	everywhere, but letting AnyEvent chose the model is generally better.
		675
		676	MAINLOOP EMULATION
		677	Sometimes (often for short test scripts, or even standalone programs who
		678	only want to use AnyEvent), you do not want to run a specific event
		679	loop.
		680
		681	In that case, you can use a condition variable like this:
		682
		683	AnyEvent->condvar->recv;
		684
		685	This has the effect of entering the event loop and looping forever.
		686
		687	Note that usually your program has some exit condition, in which case it
		688	is better to use the "traditional" approach of storing a condition
		689	variable somewhere, waiting for it, and sending it when the program
		690	should exit cleanly.
440		691
441	OTHER MODULES	692	OTHER MODULES
442	The following is a non-exhaustive list of additional modules that use	693	The following is a non-exhaustive list of additional modules that use
443	AnyEvent and can therefore be mixed easily with other AnyEvent modules	694	AnyEvent and can therefore be mixed easily with other AnyEvent modules
444	in the same program. Some of the modules come with AnyEvent, some are	695	in the same program. Some of the modules come with AnyEvent, some are
…		…
452	AnyEvent::Handle	703	AnyEvent::Handle
453	Provide read and write buffers and manages watchers for reads and	704	Provide read and write buffers and manages watchers for reads and
454	writes.	705	writes.
455		706
456	AnyEvent::Socket	707	AnyEvent::Socket
457	Provides a means to do non-blocking connects, accepts etc.	708	Provides various utility functions for (internet protocol) sockets,
		709	addresses and name resolution. Also functions to create non-blocking
		710	tcp connections or tcp servers, with IPv6 and SRV record support and
		711	more.
		712
		713	AnyEvent::DNS
		714	Provides rich asynchronous DNS resolver capabilities.
		715
		716	AnyEvent::HTTP
		717	A simple-to-use HTTP library that is capable of making a lot of
		718	concurrent HTTP requests.
458		719
459	AnyEvent::HTTPD	720	AnyEvent::HTTPD
460	Provides a simple web application server framework.	721	Provides a simple web application server framework.
461		722
462	AnyEvent::DNS
463	Provides asynchronous DNS resolver capabilities, beyond what
464	AnyEvent::Util offers.
465
466	AnyEvent::FastPing	723	AnyEvent::FastPing
467	The fastest ping in the west.	724	The fastest ping in the west.
		725
		726	AnyEvent::DBI
		727	Executes DBI requests asynchronously in a proxy process.
468		728
469	Net::IRC3	729	Net::IRC3
470	AnyEvent based IRC client module family.	730	AnyEvent based IRC client module family.
471		731
472	Net::XMPP2	732	Net::XMPP2
…		…
478		738
479	Event::ExecFlow	739	Event::ExecFlow
480	High level API for event-based execution flow control.	740	High level API for event-based execution flow control.
481		741
482	Coro	742	Coro
483	Has special support for AnyEvent.	743	Has special support for AnyEvent via Coro::AnyEvent.
		744
		745	AnyEvent::AIO, IO::AIO
		746	Truly asynchronous I/O, should be in the toolbox of every event
		747	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		748	together.
		749
		750	AnyEvent::BDB, BDB
		751	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently
		752	fuses IO::AIO and AnyEvent together.
484		753
485	IO::Lambda	754	IO::Lambda
486	The lambda approach to I/O - don't ask, look there. Can use	755	The lambda approach to I/O - don't ask, look there. Can use
487	AnyEvent.
488
489	IO::AIO
490	Truly asynchronous I/O, should be in the toolbox of every event
491	programmer. Can be trivially made to use AnyEvent.
492
493	BDB Truly asynchronous Berkeley DB access. Can be trivially made to use
494	AnyEvent.	756	AnyEvent.
495		757
496	SUPPLYING YOUR OWN EVENT MODEL INTERFACE	758	SUPPLYING YOUR OWN EVENT MODEL INTERFACE
497	This is an advanced topic that you do not normally need to use AnyEvent	759	This is an advanced topic that you do not normally need to use AnyEvent
498	in a module. This section is only of use to event loop authors who want	760	in a module. This section is only of use to event loop authors who want
…		…
551	When set to 2 or higher, cause AnyEvent to report to STDERR which	813	When set to 2 or higher, cause AnyEvent to report to STDERR which
552	event model it chooses.	814	event model it chooses.
553		815
554	"PERL_ANYEVENT_MODEL"	816	"PERL_ANYEVENT_MODEL"
555	This can be used to specify the event model to be used by AnyEvent,	817	This can be used to specify the event model to be used by AnyEvent,
556	before autodetection and -probing kicks in. It must be a string	818	before auto detection and -probing kicks in. It must be a string
557	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"	819	consisting entirely of ASCII letters. The string "AnyEvent::Impl::"
558	gets prepended and the resulting module name is loaded and if the	820	gets prepended and the resulting module name is loaded and if the
559	load was successful, used as event model. If it fails to load	821	load was successful, used as event model. If it fails to load
560	AnyEvent will proceed with autodetection and -probing.	822	AnyEvent will proceed with auto detection and -probing.
561		823
562	This functionality might change in future versions.	824	This functionality might change in future versions.
563		825
564	For example, to force the pure perl model (AnyEvent::Impl::Perl) you	826	For example, to force the pure perl model (AnyEvent::Impl::Perl) you
565	could start your program like this:	827	could start your program like this:
566		828
567	PERL_ANYEVENT_MODEL=Perl perl ...	829	PERL_ANYEVENT_MODEL=Perl perl ...
		830
		831	"PERL_ANYEVENT_PROTOCOLS"
		832	Used by both AnyEvent::DNS and AnyEvent::Socket to determine
		833	preferences for IPv4 or IPv6. The default is unspecified (and might
		834	change, or be the result of auto probing).
		835
		836	Must be set to a comma-separated list of protocols or address
		837	families, current supported: "ipv4" and "ipv6". Only protocols
		838	mentioned will be used, and preference will be given to protocols
		839	mentioned earlier in the list.
		840
		841	This variable can effectively be used for denial-of-service attacks
		842	against local programs (e.g. when setuid), although the impact is
		843	likely small, as the program has to handle connection errors
		844	already-
		845
		846	Examples: "PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6" - prefer IPv4 over
		847	IPv6, but support both and try to use both.
		848	"PERL_ANYEVENT_PROTOCOLS=ipv4" - only support IPv4, never try to
		849	resolve or contact IPv6 addresses.
		850	"PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4" support either IPv4 or IPv6, but
		851	prefer IPv6 over IPv4.
		852
		853	"PERL_ANYEVENT_EDNS0"
		854	Used by AnyEvent::DNS to decide whether to use the EDNS0 extension
		855	for DNS. This extension is generally useful to reduce DNS traffic,
		856	but some (broken) firewalls drop such DNS packets, which is why it
		857	is off by default.
		858
		859	Setting this variable to 1 will cause AnyEvent::DNS to announce
		860	EDNS0 in its DNS requests.
		861
		862	"PERL_ANYEVENT_MAX_FORKS"
		863	The maximum number of child processes that
		864	"AnyEvent::Util::fork_call" will create in parallel.
568		865
569	EXAMPLE PROGRAM	866	EXAMPLE PROGRAM
570	The following program uses an I/O watcher to read data from STDIN, a	867	The following program uses an I/O watcher to read data from STDIN, a
571	timer to display a message once per second, and a condition variable to	868	timer to display a message once per second, and a condition variable to
572	quit the program when the user enters quit:	869	quit the program when the user enters quit:
…		…
580	poll => 'r',	877	poll => 'r',
581	cb => sub {	878	cb => sub {
582	warn "io event <$_[0]>\n"; # will always output <r>	879	warn "io event <$_[0]>\n"; # will always output <r>
583	chomp (my $input = <STDIN>); # read a line	880	chomp (my $input = <STDIN>); # read a line
584	warn "read: $input\n"; # output what has been read	881	warn "read: $input\n"; # output what has been read
585	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	882	$cv->send if $input =~ /^q/i; # quit program if /^q/i
586	},	883	},
587	);	884	);
588		885
589	my $time_watcher; # can only be used once	886	my $time_watcher; # can only be used once
590		887
…		…
595	});	892	});
596	}	893	}
597		894
598	new_timer; # create first timer	895	new_timer; # create first timer
599		896
600	$cv->wait; # wait until user enters /^q/i	897	$cv->recv; # wait until user enters /^q/i
601		898
602	REAL-WORLD EXAMPLE	899	REAL-WORLD EXAMPLE
603	Consider the Net::FCP module. It features (among others) the following	900	Consider the Net::FCP module. It features (among others) the following
604	API calls, which are to freenet what HTTP GET requests are to http:	901	API calls, which are to freenet what HTTP GET requests are to http:
605		902
…		…
654	syswrite $txn->{fh}, $txn->{request}	951	syswrite $txn->{fh}, $txn->{request}
655	or die "connection or write error";	952	or die "connection or write error";
656	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	953	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
657		954
658	Again, "fh_ready_r" waits till all data has arrived, and then stores the	955	Again, "fh_ready_r" waits till all data has arrived, and then stores the
659	result and signals any possible waiters that the request ahs finished:	956	result and signals any possible waiters that the request has finished:
660		957
661	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	958	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
662		959
663	if (end-of-file or data complete) {	960	if (end-of-file or data complete) {
664	$txn->{result} = $txn->{buf};	961	$txn->{result} = $txn->{buf};
665	$txn->{finished}->broadcast;	962	$txn->{finished}->send;
666	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	963	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
667	}	964	}
668		965
669	The "result" method, finally, just waits for the finished signal (if the	966	The "result" method, finally, just waits for the finished signal (if the
670	request was already finished, it doesn't wait, of course, and returns	967	request was already finished, it doesn't wait, of course, and returns
671	the data:	968	the data:
672		969
673	$txn->{finished}->wait;	970	$txn->{finished}->recv;
674	return $txn->{result};	971	return $txn->{result};
675		972
676	The actual code goes further and collects all errors ("die"s,	973	The actual code goes further and collects all errors ("die"s,
677	exceptions) that occured during request processing. The "result" method	974	exceptions) that occurred during request processing. The "result" method
678	detects whether an exception as thrown (it is stored inside the $txn	975	detects whether an exception as thrown (it is stored inside the $txn
679	object) and just throws the exception, which means connection errors and	976	object) and just throws the exception, which means connection errors and
680	other problems get reported tot he code that tries to use the result,	977	other problems get reported tot he code that tries to use the result,
681	not in a random callback.	978	not in a random callback.
682		979
…		…
713		1010
714	my $quit = AnyEvent->condvar;	1011	my $quit = AnyEvent->condvar;
715		1012
716	$fcp->txn_client_get ($url)->cb (sub {	1013	$fcp->txn_client_get ($url)->cb (sub {
717	...	1014	...
718	$quit->broadcast;	1015	$quit->send;
719	});	1016	});
720		1017
721	$quit->wait;	1018	$quit->recv;
722		1019
723	BENCHMARKS	1020	BENCHMARKS
724	To give you an idea of the performance and overheads that AnyEvent adds	1021	To give you an idea of the performance and overheads that AnyEvent adds
725	over the event loops themselves and to give you an impression of the	1022	over the event loops themselves and to give you an impression of the
726	speed of various event loops I prepared some benchmarks.	1023	speed of various event loops I prepared some benchmarks.
727		1024
728	BENCHMARKING ANYEVENT OVERHEAD	1025	BENCHMARKING ANYEVENT OVERHEAD
729	Here is a benchmark of various supported event models used natively and	1026	Here is a benchmark of various supported event models used natively and
730	through anyevent. The benchmark creates a lot of timers (with a zero	1027	through AnyEvent. The benchmark creates a lot of timers (with a zero
731	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1028	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
732	which it is), lets them fire exactly once and destroys them again.	1029	which it is), lets them fire exactly once and destroys them again.
733		1030
734	Source code for this benchmark is found as eg/bench in the AnyEvent	1031	Source code for this benchmark is found as eg/bench in the AnyEvent
735	distribution.	1032	distribution.
…		…
751	between all watchers, to avoid adding memory overhead. That means	1048	between all watchers, to avoid adding memory overhead. That means
752	closure creation and memory usage is not included in the figures.	1049	closure creation and memory usage is not included in the figures.
753		1050
754	invoke is the time, in microseconds, used to invoke a simple callback.	1051	invoke is the time, in microseconds, used to invoke a simple callback.
755	The callback simply counts down a Perl variable and after it was invoked	1052	The callback simply counts down a Perl variable and after it was invoked
756	"watcher" times, it would "->broadcast" a condvar once to signal the end	1053	"watcher" times, it would "->send" a condvar once to signal the end of
757	of this phase.	1054	this phase.
758		1055
759	destroy is the time, in microseconds, that it takes to destroy a	1056	destroy is the time, in microseconds, that it takes to destroy a
760	single watcher.	1057	single watcher.
761		1058
762	Results	1059	Results
…		…
823	the figures above).	1120	the figures above).
824		1121
825	"POE", regardless of underlying event loop (whether using its pure perl	1122	"POE", regardless of underlying event loop (whether using its pure perl
826	select-based backend or the Event module, the POE-EV backend couldn't be	1123	select-based backend or the Event module, the POE-EV backend couldn't be
827	tested because it wasn't working) shows abysmal performance and memory	1124	tested because it wasn't working) shows abysmal performance and memory
828	usage: Watchers use almost 30 times as much memory as EV watchers, and	1125	usage with AnyEvent: Watchers use almost 30 times as much memory as EV
829	10 times as much memory as Event (the high memory requirements are	1126	watchers, and 10 times as much memory as Event (the high memory
830	caused by requiring a session for each watcher). Watcher invocation	1127	requirements are caused by requiring a session for each watcher).
831	speed is almost 900 times slower than with AnyEvent's pure perl	1128	Watcher invocation speed is almost 900 times slower than with AnyEvent's
		1129	pure perl implementation.
		1130
832	implementation. The design of the POE adaptor class in AnyEvent can not	1131	The design of the POE adaptor class in AnyEvent can not really account
833	really account for this, as session creation overhead is small compared	1132	for the performance issues, though, as session creation overhead is
834	to execution of the state machine, which is coded pretty optimally	1133	small compared to execution of the state machine, which is coded pretty
835	within AnyEvent::Impl::POE. POE simply seems to be abysmally slow.	1134	optimally within AnyEvent::Impl::POE (and while everybody agrees that
		1135	using multiple sessions is not a good approach, especially regarding
		1136	memory usage, even the author of POE could not come up with a faster
		1137	design).
836		1138
837	Summary	1139	Summary
838	* Using EV through AnyEvent is faster than any other event loop (even	1140	* Using EV through AnyEvent is faster than any other event loop (even
839	when used without AnyEvent), but most event loops have acceptable	1141	when used without AnyEvent), but most event loops have acceptable
840	performance with or without AnyEvent.	1142	performance with or without AnyEvent.
…		…
845		1147
846	* You should avoid POE like the plague if you want performance or	1148	* You should avoid POE like the plague if you want performance or
847	reasonable memory usage.	1149	reasonable memory usage.
848		1150
849	BENCHMARKING THE LARGE SERVER CASE	1151	BENCHMARKING THE LARGE SERVER CASE
850	This benchmark atcually benchmarks the event loop itself. It works by	1152	This benchmark actually benchmarks the event loop itself. It works by
851	creating a number of "servers": each server consists of a socketpair, a	1153	creating a number of "servers": each server consists of a socket pair, a
852	timeout watcher that gets reset on activity (but never fires), and an	1154	timeout watcher that gets reset on activity (but never fires), and an
853	I/O watcher waiting for input on one side of the socket. Each time the	1155	I/O watcher waiting for input on one side of the socket. Each time the
854	socket watcher reads a byte it will write that byte to a random other	1156	socket watcher reads a byte it will write that byte to a random other
855	"server".	1157	"server".
856		1158
857	The effect is that there will be a lot of I/O watchers, only part of	1159	The effect is that there will be a lot of I/O watchers, only part of
858	which are active at any one point (so there is a constant number of	1160	which are active at any one point (so there is a constant number of
859	active fds for each loop iterstaion, but which fds these are is random).	1161	active fds for each loop iteration, but which fds these are is random).
860	The timeout is reset each time something is read because that reflects	1162	The timeout is reset each time something is read because that reflects
861	how most timeouts work (and puts extra pressure on the event loops).	1163	how most timeouts work (and puts extra pressure on the event loops).
862		1164
863	In this benchmark, we use 10000 socketpairs (20000 sockets), of which	1165	In this benchmark, we use 10000 socket pairs (20000 sockets), of which
864	100 (1%) are active. This mirrors the activity of large servers with	1166	100 (1%) are active. This mirrors the activity of large servers with
865	many connections, most of which are idle at any one point in time.	1167	many connections, most of which are idle at any one point in time.
866		1168
867	Source code for this benchmark is found as eg/bench2 in the AnyEvent	1169	Source code for this benchmark is found as eg/bench2 in the AnyEvent
868	distribution.	1170	distribution.
869		1171
870	Explanation of the columns	1172	Explanation of the columns
871	sockets is the number of sockets, and twice the number of "servers"	1173	sockets is the number of sockets, and twice the number of "servers"
872	(as each server has a read and write socket end).	1174	(as each server has a read and write socket end).
873		1175
874	create is the time it takes to create a socketpair (which is	1176	create is the time it takes to create a socket pair (which is
875	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1177	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
876		1178
877	request, the most important value, is the time it takes to handle a	1179	request, the most important value, is the time it takes to handle a
878	single "request", that is, reading the token from the pipe and	1180	single "request", that is, reading the token from the pipe and
879	forwarding it to another server. This includes deleting the old timeout	1181	forwarding it to another server. This includes deleting the old timeout
…		…
909	POE is still completely out of the picture, taking over 1000 times as	1211	POE is still completely out of the picture, taking over 1000 times as
910	long as EV, and over 100 times as long as the Perl implementation, even	1212	long as EV, and over 100 times as long as the Perl implementation, even
911	though it uses a C-based event loop in this case.	1213	though it uses a C-based event loop in this case.
912		1214
913	Summary	1215	Summary
914	* The pure perl implementation performs extremely well, considering	1216	* The pure perl implementation performs extremely well.
915	that it uses select.
916		1217
917	* Avoid Glib or POE in large projects where performance matters.	1218	* Avoid Glib or POE in large projects where performance matters.
918		1219
919	BENCHMARKING SMALL SERVERS	1220	BENCHMARKING SMALL SERVERS
920	While event loops should scale (and select-based ones do not...) even to	1221	While event loops should scale (and select-based ones do not...) even to
…		…
944	and speed most when you have lots of watchers, not when you only have a	1245	and speed most when you have lots of watchers, not when you only have a
945	few of them).	1246	few of them).
946		1247
947	EV is again fastest.	1248	EV is again fastest.
948		1249
949	Perl again comes second. It is noticably faster than the C-based event	1250	Perl again comes second. It is noticeably faster than the C-based event
950	loops Event and Glib, although the difference is too small to really	1251	loops Event and Glib, although the difference is too small to really
951	matter.	1252	matter.
952		1253
953	POE also performs much better in this case, but is is still far behind	1254	POE also performs much better in this case, but is is still far behind
954	the others.	1255	the others.
…		…
957	* C-based event loops perform very well with small number of watchers,	1258	* C-based event loops perform very well with small number of watchers,
958	as the management overhead dominates.	1259	as the management overhead dominates.
959		1260
960	FORK	1261	FORK
961	Most event libraries are not fork-safe. The ones who are usually are	1262	Most event libraries are not fork-safe. The ones who are usually are
962	because they are so inefficient. Only EV is fully fork-aware.	1263	because they rely on inefficient but fork-safe "select" or "poll" calls.
		1264	Only EV is fully fork-aware.
963		1265
964	If you have to fork, you must either do so before creating your first	1266	If you have to fork, you must either do so before creating your first
965	watcher OR you must not use AnyEvent at all in the child.	1267	watcher OR you must not use AnyEvent at all in the child.
966		1268
967	SECURITY CONSIDERATIONS	1269	SECURITY CONSIDERATIONS
…		…
973	model than specified in the variable.	1275	model than specified in the variable.
974		1276
975	You can make AnyEvent completely ignore this variable by deleting it	1277	You can make AnyEvent completely ignore this variable by deleting it
976	before the first watcher gets created, e.g. with a "BEGIN" block:	1278	before the first watcher gets created, e.g. with a "BEGIN" block:
977		1279
978	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1280	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
979		1281
980	use AnyEvent;	1282	use AnyEvent;
		1283
		1284	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1285	be used to probe what backend is used and gain other information (which
		1286	is probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1287
		1288	BUGS
		1289	Perl 5.8 has numerous memleaks that sometimes hit this module and are
		1290	hard to work around. If you suffer from memleaks, first upgrade to Perl
		1291	5.10 and check wether the leaks still show up. (Perl 5.10.0 has other
		1292	annoying mamleaks, such as leaking on "map" and "grep" but it is usually
		1293	not as pronounced).
981		1294
982	SEE ALSO	1295	SEE ALSO
983	Event modules: Coro::EV, EV, EV::Glib, Glib::EV, Coro::Event, Event,	1296	Utility functions: AnyEvent::Util.
984	Glib::Event, Glib, Coro, Tk, Event::Lib, Qt, POE.
985		1297
986	Implementations: AnyEvent::Impl::CoroEV, AnyEvent::Impl::EV,	1298	Event modules: EV, EV::Glib, Glib::EV, Event, Glib::Event, Glib, Tk,
987	AnyEvent::Impl::CoroEvent, AnyEvent::Impl::Event, AnyEvent::Impl::Glib,	1299	Event::Lib, Qt, POE.
988	AnyEvent::Impl::Tk, AnyEvent::Impl::Perl, AnyEvent::Impl::EventLib,	1300
		1301	Implementations: AnyEvent::Impl::EV, AnyEvent::Impl::Event,
		1302	AnyEvent::Impl::Glib, AnyEvent::Impl::Tk, AnyEvent::Impl::Perl,
989	AnyEvent::Impl::Qt, AnyEvent::Impl::POE.	1303	AnyEvent::Impl::EventLib, AnyEvent::Impl::Qt, AnyEvent::Impl::POE.
990		1304
		1305	Non-blocking file handles, sockets, TCP clients and servers:
		1306	AnyEvent::Handle, AnyEvent::Socket.
		1307
		1308	Asynchronous DNS: AnyEvent::DNS.
		1309
		1310	Coroutine support: Coro, Coro::AnyEvent, Coro::EV, Coro::Event,
		1311
991	Nontrivial usage examples: Net::FCP, Net::XMPP2.	1312	Nontrivial usage examples: Net::FCP, Net::XMPP2, AnyEvent::DNS.
992		1313
993	AUTHOR	1314	AUTHOR
994	Marc Lehmann <schmorp@schmorp.de>	1315	Marc Lehmann <schmorp@schmorp.de>
995	http://home.schmorp.de/	1316	http://home.schmorp.de/
996		1317

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Comparing AnyEvent/README (file contents): Revision 1.19 by root, Mon Apr 28 08:02:14 2008 UTC vs. Revision 1.27 by root, Sun Jun 22 12:17:47 2008 UTC

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Comparing AnyEvent/README (file contents):
Revision 1.19 by root, Mon Apr 28 08:02:14 2008 UTC vs.
Revision 1.27 by root, Sun Jun 22 12:17:47 2008 UTC