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Revision 1.181 by root, Sat Sep 6 10:54:32 2008 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
		12
		13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
12	...	23	...
13	});	24	});
14		25
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...
17	});
18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		27	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	28	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	48	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	49	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	63	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	64	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
…		…
78	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
79	module.	101	module.
80		102
81	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
82	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
86	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
88	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
114		136
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
118	is in control).	140	is in control).
…		…
126	Many watchers either are used with "recursion" (repeating timers for	148	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	149	example), or need to refer to their watcher object in other ways.
128		150
129	An any way to achieve that is this pattern:	151	An any way to achieve that is this pattern:
130		152
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	154	# you can use $w here, for example to undef it
133	undef $w;	155	undef $w;
134	});	156	});
135		157
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	158	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	159	my variables are only visible after the statement in which they are
138	declared.	160	declared.
139		161
140	=head2 I/O WATCHERS	162	=head2 I/O WATCHERS
141		163
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	165	with the following mandatory key-value pairs as arguments:
144		166
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
146	for events. C<poll> must be a string that is either C<r> or C<w>,	168	(AnyEvent might or might not keep a reference to this file handle). C<poll>
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	169	must be a string that is either C<r> or C<w>, which creates a watcher
148	respectively. C<cb> is the callback to invoke each time the file handle	170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149	becomes ready.	171	callback to invoke each time the file handle becomes ready.
150		172
151	Although the callback might get passed parameters, their value and	173	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	174	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	175	callbacks cannot use arguments passed to I/O watcher callbacks.
154		176
…		…
158		180
159	Some event loops issue spurious readyness notifications, so you should	181	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	182	always use non-blocking calls when reading/writing from/to your file
161	handles.	183	handles.
162		184
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	185	Example: wait for readability of STDIN, then read a line and disable the
		186	watcher.
		187
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	188	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	189	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	190	warn "read: $input\n";
169	undef $w;	191	undef $w;
170	});	192	});
…		…
180		202
181	Although the callback might get passed parameters, their value and	203	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	204	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	205	callbacks cannot use arguments passed to time watcher callbacks.
184		206
185	The timer callback will be invoked at most once: if you want a repeating	207	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	208	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	209	callback will be invoked regularly at that interval (in fractional
		210	seconds) after the first invocation. If C<interval> is specified with a
		211	false value, then it is treated as if it were missing.
188		212
189	Example:	213	The callback will be rescheduled before invoking the callback, but no
		214	attempt is done to avoid timer drift in most backends, so the interval is
		215	only approximate.
190		216
191	# fire an event after 7.7 seconds	217	Example: fire an event after 7.7 seconds.
		218
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	219	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	220	warn "timeout\n";
194	});	221	});
195		222
196	# to cancel the timer:	223	# to cancel the timer:
197	undef $w;	224	undef $w;
198		225
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	226	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		227
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	228	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		229	warn "timeout\n";
207	};	230	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		231
212	=head3 TIMING ISSUES	232	=head3 TIMING ISSUES
213		233
214	There are two ways to handle timers: based on real time (relative, "fire	234	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	235	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	247	timers.
228		248
229	AnyEvent always prefers relative timers, if available, matching the	249	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	250	AnyEvent API.
231		251
		252	AnyEvent has two additional methods that return the "current time":
		253
		254	=over 4
		255
		256	=item AnyEvent->time
		257
		258	This returns the "current wallclock time" as a fractional number of
		259	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		260	return, and the result is guaranteed to be compatible with those).
		261
		262	It progresses independently of any event loop processing, i.e. each call
		263	will check the system clock, which usually gets updated frequently.
		264
		265	=item AnyEvent->now
		266
		267	This also returns the "current wallclock time", but unlike C<time>, above,
		268	this value might change only once per event loop iteration, depending on
		269	the event loop (most return the same time as C<time>, above). This is the
		270	time that AnyEvent's timers get scheduled against.
		271
		272	I<In almost all cases (in all cases if you don't care), this is the
		273	function to call when you want to know the current time.>
		274
		275	This function is also often faster then C<< AnyEvent->time >>, and
		276	thus the preferred method if you want some timestamp (for example,
		277	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		278
		279	The rest of this section is only of relevance if you try to be very exact
		280	with your timing, you can skip it without bad conscience.
		281
		282	For a practical example of when these times differ, consider L<Event::Lib>
		283	and L<EV> and the following set-up:
		284
		285	The event loop is running and has just invoked one of your callback at
		286	time=500 (assume no other callbacks delay processing). In your callback,
		287	you wait a second by executing C<sleep 1> (blocking the process for a
		288	second) and then (at time=501) you create a relative timer that fires
		289	after three seconds.
		290
		291	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		292	both return C<501>, because that is the current time, and the timer will
		293	be scheduled to fire at time=504 (C<501> + C<3>).
		294
		295	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		296	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		297	last event processing phase started. With L<EV>, your timer gets scheduled
		298	to run at time=503 (C<500> + C<3>).
		299
		300	In one sense, L<Event::Lib> is more exact, as it uses the current time
		301	regardless of any delays introduced by event processing. However, most
		302	callbacks do not expect large delays in processing, so this causes a
		303	higher drift (and a lot more system calls to get the current time).
		304
		305	In another sense, L<EV> is more exact, as your timer will be scheduled at
		306	the same time, regardless of how long event processing actually took.
		307
		308	In either case, if you care (and in most cases, you don't), then you
		309	can get whatever behaviour you want with any event loop, by taking the
		310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		311	account.
		312
		313	=back
		314
232	=head2 SIGNAL WATCHERS	315	=head2 SIGNAL WATCHERS
233		316
234	You can watch for signals using a signal watcher, C<signal> is the signal	317	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	319	callback to be invoked whenever a signal occurs.
237		320
238	Although the callback might get passed parameters, their value and	321	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	322	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	323	callbacks cannot use arguments passed to signal watcher callbacks.
241		324
242	Multiple signal occurances can be clumped together into one callback	325	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	326	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	327	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	328	but it is guaranteed not to interrupt any other callbacks.
246		329
247	The main advantage of using these watchers is that you can share a signal	330	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	331	between multiple watchers.
249		332
250	This watcher might use C<%SIG>, so programs overwriting those signals	333	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	340	=head2 CHILD PROCESS WATCHERS
258		341
259	You can also watch on a child process exit and catch its exit status.	342	You can also watch on a child process exit and catch its exit status.
260		343
261	The child process is specified by the C<pid> argument (if set to C<0>, it	344	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	345	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	346	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	347	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	348
266	you I<can> rely on child watcher callback arguments.	349	The callback will be called with the pid and exit status (as returned by
		350	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		351	callback arguments.
		352
		353	This watcher type works by installing a signal handler for C<SIGCHLD>,
		354	and since it cannot be shared, nothing else should use SIGCHLD or reap
		355	random child processes (waiting for specific child processes, e.g. inside
		356	C<system>, is just fine).
267		357
268	There is a slight catch to child watchers, however: you usually start them	358	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	359	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	360	have exited already (and no SIGCHLD will be sent anymore).
271		361
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	367	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	368	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		369
280	Example: fork a process and wait for it	370	Example: fork a process and wait for it
281		371
282	my $done = AnyEvent->condvar;	372	my $done = AnyEvent->condvar;
283		373
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	374	my $pid = fork or exit 5;
287		375
288	my $w = AnyEvent->child (	376	my $w = AnyEvent->child (
289	pid => $pid,	377	pid => $pid,
290	cb => sub {	378	cb => sub {
291	my ($pid, $status) = @_;	379	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	380	warn "pid $pid exited with status $status";
293	$done->broadcast;	381	$done->send;
294	},	382	},
295	);	383	);
296		384
297	# do something else, then wait for process exit	385	# do something else, then wait for process exit
298	$done->wait;	386	$done->recv;
299		387
300	=head2 CONDITION VARIABLES	388	=head2 CONDITION VARIABLES
301		389
302	If you are familiar with some event loops you will know that all of them	390	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	391	require you to run some blocking "loop", "run" or similar function that
…		…
309	The instrument to do that is called a "condition variable", so called	397	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	398	because they represent a condition that must become true.
311		399
312	Condition variables can be created by calling the C<< AnyEvent->condvar	400	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	401	>> method, usually without arguments. The only argument pair allowed is
		402
314	C<cb>, which specifies a callback to be called when the condition variable	403	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	404	becomes true, with the condition variable as the first argument (but not
		405	the results).
316		406
317	After creation, the conditon variable is "false" until it becomes "true"	407	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	408	by calling the C<send> method (or calling the condition variable as if it
		409	were a callback, read about the caveats in the description for the C<<
		410	->send >> method).
319		411
320	Condition variables are similar to callbacks, except that you can	412	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	413	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	414	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	415	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	416	used to represent a transaction, which finishes at some point and delivers
325	a result.	417	a result.
326		418
327	Condition variables are very useful to signal that something has finished,	419	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	420	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	421	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	422	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	423	called or can synchronously C<< ->recv >> for the results.
332		424
333	You can also use them to simulate traditional event loops - for example,	425	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	426	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	427	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->broadcast >> the "quit" event.	428	button of your app, which would C<< ->send >> the "quit" event.
337		429
338	Note that condition variables recurse into the event loop - if you have	430	Note that condition variables recurse into the event loop - if you have
339	two pieces of code that call C<< ->wait >> in a round-robbin fashion, you	431	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	432	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	433	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	434	as this asks for trouble.
343		435
344	Condition variables are represented by hash refs in perl, and the keys	436	Condition variables are represented by hash refs in perl, and the keys
…		…
346	easy (it is often useful to build your own transaction class on top of	438	easy (it is often useful to build your own transaction class on top of
347	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	439	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	440	it's C<new> method in your own C<new> method.
349		441
350	There are two "sides" to a condition variable - the "producer side" which	442	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	443	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	444	for the send to occur.
353		445
354	Example:	446	Example: wait for a timer.
355		447
356	# wait till the result is ready	448	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	449	my $result_ready = AnyEvent->condvar;
358		450
359	# do something such as adding a timer	451	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	452	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	453	# when the "result" is ready.
362	# in this case, we simply use a timer:	454	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	455	my $w = AnyEvent->timer (
364	after => 1,	456	after => 1,
365	cb => sub { $result_ready->broadcast },	457	cb => sub { $result_ready->send },
366	);	458	);
367		459
368	# this "blocks" (while handling events) till the callback	460	# this "blocks" (while handling events) till the callback
369	# calls broadcast	461	# calls send
370	$result_ready->wait;	462	$result_ready->recv;
		463
		464	Example: wait for a timer, but take advantage of the fact that
		465	condition variables are also code references.
		466
		467	my $done = AnyEvent->condvar;
		468	my $delay = AnyEvent->timer (after => 5, cb => $done);
		469	$done->recv;
		470
		471	Example: Imagine an API that returns a condvar and doesn't support
		472	callbacks. This is how you make a synchronous call, for example from
		473	the main program:
		474
		475	use AnyEvent::CouchDB;
		476
		477	...
		478
		479	my @info = $couchdb->info->recv;
		480
		481	And this is how you would just ste a callback to be called whenever the
		482	results are available:
		483
		484	$couchdb->info->cb (sub {
		485	my @info = $_[0]->recv;
		486	});
371		487
372	=head3 METHODS FOR PRODUCERS	488	=head3 METHODS FOR PRODUCERS
373		489
374	These methods should only be used by the producing side, i.e. the	490	These methods should only be used by the producing side, i.e. the
375	code/module that eventually broadcasts the signal. Note that it is also	491	code/module that eventually sends the signal. Note that it is also
376	the producer side which creates the condvar in most cases, but it isn't	492	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	493	uncommon for the consumer to create it as well.
378		494
379	=over 4	495	=over 4
380		496
381	=item $cv->broadcast (...)	497	=item $cv->send (...)
382		498
383	Flag the condition as ready - a running C<< ->wait >> and all further	499	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	500	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	501	called. If nobody is waiting the send will be remembered.
386		502
387	If a callback has been set on the condition variable, it is called	503	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	504	immediately from within send.
389		505
390	Any arguments passed to the C<broadcast> call will be returned by all	506	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	507	future C<< ->recv >> calls.
		508
		509	Condition variables are overloaded so one can call them directly
		510	(as a code reference). Calling them directly is the same as calling
		511	C<send>. Note, however, that many C-based event loops do not handle
		512	overloading, so as tempting as it may be, passing a condition variable
		513	instead of a callback does not work. Both the pure perl and EV loops
		514	support overloading, however, as well as all functions that use perl to
		515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		516	example).
392		517
393	=item $cv->croak ($error)	518	=item $cv->croak ($error)
394		519
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	520	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	521	C<Carp::croak> with the given error message/object/scalar.
397		522
398	This can be used to signal any errors to the condition variable	523	This can be used to signal any errors to the condition variable
399	user/consumer.	524	user/consumer.
400		525
401	=item $cv->begin ([group callback])	526	=item $cv->begin ([group callback])
402		527
403	=item $cv->end	528	=item $cv->end
		529
		530	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		531
405	These two methods can be used to combine many transactions/events into	532	These two methods can be used to combine many transactions/events into
406	one. For example, a function that pings many hosts in parallel might want	533	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	534	to use a condition variable for the whole process.
408		535
409	Every call to C<< ->begin >> will increment a counter, and every call to	536	Every call to C<< ->begin >> will increment a counter, and every call to
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	537	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	538	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->broadcast >>, but that is not required. If no	539	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<broadcast> will be called without any arguments.	540	callback was set, C<send> will be called without any arguments.
414		541
415	Let's clarify this with the ping example:	542	Let's clarify this with the ping example:
416		543
417	my $cv = AnyEvent->condvar;	544	my $cv = AnyEvent->condvar;
418		545
419	my %result;	546	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	547	$cv->begin (sub { $cv->send (\%result) });
421		548
422	for my $host (@list_of_hosts) {	549	for my $host (@list_of_hosts) {
423	$cv->begin;	550	$cv->begin;
424	ping_host_then_call_callback $host, sub {	551	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	552	$result{$host} = ...;
…		…
428	}	555	}
429		556
430	$cv->end;	557	$cv->end;
431		558
432	This code fragment supposedly pings a number of hosts and calls	559	This code fragment supposedly pings a number of hosts and calls
433	C<broadcast> after results for all then have have been gathered - in any	560	C<send> after results for all then have have been gathered - in any
434	order. To achieve this, the code issues a call to C<begin> when it starts	561	order. To achieve this, the code issues a call to C<begin> when it starts
435	each ping request and calls C<end> when it has received some result for	562	each ping request and calls C<end> when it has received some result for
436	it. Since C<begin> and C<end> only maintain a counter, the order in which	563	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	564	results arrive is not relevant.
438		565
439	There is an additional bracketing call to C<begin> and C<end> outside the	566	There is an additional bracketing call to C<begin> and C<end> outside the
440	loop, which serves two important purposes: first, it sets the callback	567	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	568	to be called once the counter reaches C<0>, and second, it ensures that
442	broadcast is called even when C<no> hosts are being pinged (the loop	569	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	570	doesn't execute once).
444		571
445	This is the general pattern when you "fan out" into multiple subrequests:	572	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	573	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	574	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	575	C<begin> and for each subrequest you finish, call C<end>.
449		576
450	=back	577	=back
451		578
452	=head3 METHODS FOR CONSUMERS	579	=head3 METHODS FOR CONSUMERS
453		580
454	These methods should only be used by the consuming side, i.e. the	581	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	582	code awaits the condition.
456		583
457	=item $cv->wait	584	=over 4
458		585
		586	=item $cv->recv
		587
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	588	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	589	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	590	normally.
462		591
463	You can only wait once on a condition - additional calls are valid but	592	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	593	will return immediately.
465		594
466	If an error condition has been set by calling C<< ->croak >>, then this	595	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	596	function will call C<croak>.
468		597
469	In list context, all parameters passed to C<broadcast> will be returned,	598	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	599	in scalar context only the first one will be returned.
471		600
472	Not all event models support a blocking wait - some die in that case	601	Not all event models support a blocking wait - some die in that case
473	(programs might want to do that to stay interactive), so I<if you are	602	(programs might want to do that to stay interactive), so I<if you are
474	using this from a module, never require a blocking wait>, but let the	603	using this from a module, never require a blocking wait>, but let the
475	caller decide whether the call will block or not (for example, by coupling	604	caller decide whether the call will block or not (for example, by coupling
476	condition variables with some kind of request results and supporting	605	condition variables with some kind of request results and supporting
477	callbacks so the caller knows that getting the result will not block,	606	callbacks so the caller knows that getting the result will not block,
478	while still suppporting blocking waits if the caller so desires).	607	while still supporting blocking waits if the caller so desires).
479		608
480	Another reason I<never> to C<< ->wait >> in a module is that you cannot	609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
481	sensibly have two C<< ->wait >>'s in parallel, as that would require	610	sensibly have two C<< ->recv >>'s in parallel, as that would require
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	612	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		613
		614	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		615	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		616	versions and also integrates coroutines into AnyEvent, making blocking
		617	C<< ->recv >> calls perfectly safe as long as they are done from another
		618	coroutine (one that doesn't run the event loop).
		619
487	You can ensure that C<< -wait >> never blocks by setting a callback and	620	You can ensure that C<< -recv >> never blocks by setting a callback and
488	only calling C<< ->wait >> from within that callback (or at a later	621	only calling C<< ->recv >> from within that callback (or at a later
489	time). This will work even when the event loop does not support blocking	622	time). This will work even when the event loop does not support blocking
490	waits otherwise.	623	waits otherwise.
		624
		625	=item $bool = $cv->ready
		626
		627	Returns true when the condition is "true", i.e. whether C<send> or
		628	C<croak> have been called.
		629
		630	=item $cb = $cv->cb ($cb->($cv))
		631
		632	This is a mutator function that returns the callback set and optionally
		633	replaces it before doing so.
		634
		635	The callback will be called when the condition becomes "true", i.e. when
		636	C<send> or C<croak> are called, with the only argument being the condition
		637	variable itself. Calling C<recv> inside the callback or at any later time
		638	is guaranteed not to block.
491		639
492	=back	640	=back
493		641
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	642	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		643
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	651	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	652	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		653
506	The known classes so far are:	654	The known classes so far are:
507		655
508	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	656	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	657	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	658	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	659	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	660	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	677	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	if necessary. You should only call this function right before you would	678	if necessary. You should only call this function right before you would
533	have created an AnyEvent watcher anyway, that is, as late as possible at	679	have created an AnyEvent watcher anyway, that is, as late as possible at
534	runtime.	680	runtime.
535		681
		682	=item $guard = AnyEvent::post_detect { BLOCK }
		683
		684	Arranges for the code block to be executed as soon as the event model is
		685	autodetected (or immediately if this has already happened).
		686
		687	If called in scalar or list context, then it creates and returns an object
		688	that automatically removes the callback again when it is destroyed. See
		689	L<Coro::BDB> for a case where this is useful.
		690
		691	=item @AnyEvent::post_detect
		692
		693	If there are any code references in this array (you can C<push> to it
		694	before or after loading AnyEvent), then they will called directly after
		695	the event loop has been chosen.
		696
		697	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		698	if it contains a true value then the event loop has already been detected,
		699	and the array will be ignored.
		700
		701	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		702
536	=back	703	=back
537		704
538	=head1 WHAT TO DO IN A MODULE	705	=head1 WHAT TO DO IN A MODULE
539		706
540	As a module author, you should C<use AnyEvent> and call AnyEvent methods	707	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
543	Be careful when you create watchers in the module body - AnyEvent will	710	Be careful when you create watchers in the module body - AnyEvent will
544	decide which event module to use as soon as the first method is called, so	711	decide which event module to use as soon as the first method is called, so
545	by calling AnyEvent in your module body you force the user of your module	712	by calling AnyEvent in your module body you force the user of your module
546	to load the event module first.	713	to load the event module first.
547		714
548	Never call C<< ->wait >> on a condition variable unless you I<know> that	715	Never call C<< ->recv >> on a condition variable unless you I<know> that
549	the C<< ->broadcast >> method has been called on it already. This is	716	the C<< ->send >> method has been called on it already. This is
550	because it will stall the whole program, and the whole point of using	717	because it will stall the whole program, and the whole point of using
551	events is to stay interactive.	718	events is to stay interactive.
552		719
553	It is fine, however, to call C<< ->wait >> when the user of your module	720	It is fine, however, to call C<< ->recv >> when the user of your module
554	requests it (i.e. if you create a http request object ad have a method	721	requests it (i.e. if you create a http request object ad have a method
555	called C<results> that returns the results, it should call C<< ->wait >>	722	called C<results> that returns the results, it should call C<< ->recv >>
556	freely, as the user of your module knows what she is doing. always).	723	freely, as the user of your module knows what she is doing. always).
557		724
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	725	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		726
560	There will always be a single main program - the only place that should	727	There will always be a single main program - the only place that should
…		…
562		729
563	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	730	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
564	do anything special (it does not need to be event-based) and let AnyEvent	731	do anything special (it does not need to be event-based) and let AnyEvent
565	decide which implementation to chose if some module relies on it.	732	decide which implementation to chose if some module relies on it.
566		733
567	If the main program relies on a specific event model. For example, in	734	If the main program relies on a specific event model - for example, in
568	Gtk2 programs you have to rely on the Glib module. You should load the	735	Gtk2 programs you have to rely on the Glib module - you should load the
569	event module before loading AnyEvent or any module that uses it: generally	736	event module before loading AnyEvent or any module that uses it: generally
570	speaking, you should load it as early as possible. The reason is that	737	speaking, you should load it as early as possible. The reason is that
571	modules might create watchers when they are loaded, and AnyEvent will	738	modules might create watchers when they are loaded, and AnyEvent will
572	decide on the event model to use as soon as it creates watchers, and it	739	decide on the event model to use as soon as it creates watchers, and it
573	might chose the wrong one unless you load the correct one yourself.	740	might chose the wrong one unless you load the correct one yourself.
574		741
575	You can chose to use a rather inefficient pure-perl implementation by	742	You can chose to use a pure-perl implementation by loading the
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	743	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	behaviour everywhere, but letting AnyEvent chose is generally better.	744	everywhere, but letting AnyEvent chose the model is generally better.
		745
		746	=head2 MAINLOOP EMULATION
		747
		748	Sometimes (often for short test scripts, or even standalone programs who
		749	only want to use AnyEvent), you do not want to run a specific event loop.
		750
		751	In that case, you can use a condition variable like this:
		752
		753	AnyEvent->condvar->recv;
		754
		755	This has the effect of entering the event loop and looping forever.
		756
		757	Note that usually your program has some exit condition, in which case
		758	it is better to use the "traditional" approach of storing a condition
		759	variable somewhere, waiting for it, and sending it when the program should
		760	exit cleanly.
		761
578		762
579	=head1 OTHER MODULES	763	=head1 OTHER MODULES
580		764
581	The following is a non-exhaustive list of additional modules that use	765	The following is a non-exhaustive list of additional modules that use
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	766	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
588	=item L<AnyEvent::Util>	772	=item L<AnyEvent::Util>
589		773
590	Contains various utility functions that replace often-used but blocking	774	Contains various utility functions that replace often-used but blocking
591	functions such as C<inet_aton> by event-/callback-based versions.	775	functions such as C<inet_aton> by event-/callback-based versions.
592		776
		777	=item L<AnyEvent::Socket>
		778
		779	Provides various utility functions for (internet protocol) sockets,
		780	addresses and name resolution. Also functions to create non-blocking tcp
		781	connections or tcp servers, with IPv6 and SRV record support and more.
		782
593	=item L<AnyEvent::Handle>	783	=item L<AnyEvent::Handle>
594		784
595	Provide read and write buffers and manages watchers for reads and writes.	785	Provide read and write buffers, manages watchers for reads and writes,
		786	supports raw and formatted I/O, I/O queued and fully transparent and
		787	non-blocking SSL/TLS.
596		788
597	=item L<AnyEvent::Socket>	789	=item L<AnyEvent::DNS>
598		790
599	Provides a means to do non-blocking connects, accepts etc.	791	Provides rich asynchronous DNS resolver capabilities.
		792
		793	=item L<AnyEvent::HTTP>
		794
		795	A simple-to-use HTTP library that is capable of making a lot of concurrent
		796	HTTP requests.
600		797
601	=item L<AnyEvent::HTTPD>	798	=item L<AnyEvent::HTTPD>
602		799
603	Provides a simple web application server framework.	800	Provides a simple web application server framework.
604		801
605	=item L<AnyEvent::DNS>
606
607	Provides asynchronous DNS resolver capabilities, beyond what
608	L<AnyEvent::Util> offers.
609
610	=item L<AnyEvent::FastPing>	802	=item L<AnyEvent::FastPing>
611		803
612	The fastest ping in the west.	804	The fastest ping in the west.
		805
		806	=item L<AnyEvent::DBI>
		807
		808	Executes L<DBI> requests asynchronously in a proxy process.
		809
		810	=item L<AnyEvent::AIO>
		811
		812	Truly asynchronous I/O, should be in the toolbox of every event
		813	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		814	together.
		815
		816	=item L<AnyEvent::BDB>
		817
		818	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		819	L<BDB> and AnyEvent together.
		820
		821	=item L<AnyEvent::GPSD>
		822
		823	A non-blocking interface to gpsd, a daemon delivering GPS information.
		824
		825	=item L<AnyEvent::IGS>
		826
		827	A non-blocking interface to the Internet Go Server protocol (used by
		828	L<App::IGS>).
613		829
614	=item L<Net::IRC3>	830	=item L<Net::IRC3>
615		831
616	AnyEvent based IRC client module family.	832	AnyEvent based IRC client module family.
617		833
…		…
628		844
629	High level API for event-based execution flow control.	845	High level API for event-based execution flow control.
630		846
631	=item L<Coro>	847	=item L<Coro>
632		848
633	Has special support for AnyEvent.	849	Has special support for AnyEvent via L<Coro::AnyEvent>.
634		850
635	=item L<IO::Lambda>	851	=item L<IO::Lambda>
636		852
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638		854
639	=item L<IO::AIO>
640
641	Truly asynchronous I/O, should be in the toolbox of every event
642	programmer. Can be trivially made to use AnyEvent.
643
644	=item L<BDB>
645
646	Truly asynchronous Berkeley DB access. Can be trivially made to use
647	AnyEvent.
648
649	=back	855	=back
650		856
651	=cut	857	=cut
652		858
653	package AnyEvent;	859	package AnyEvent;
654		860
655	no warnings;	861	no warnings;
656	use strict;	862	use strict qw(vars subs);
657		863
658	use Carp;	864	use Carp;
659		865
660	our $VERSION = '3.3';	866	our $VERSION = 4.234;
661	our $MODEL;	867	our $MODEL;
662		868
663	our $AUTOLOAD;	869	our $AUTOLOAD;
664	our @ISA;	870	our @ISA;
665		871
		872	our @REGISTRY;
		873
		874	our $WIN32;
		875
		876	BEGIN {
		877	my $win32 = ! ! ($^O =~ /mswin32/i);
		878	eval "sub WIN32(){ $win32 }";
		879	}
		880
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		882
668	our @REGISTRY;	883	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		884
		885	{
		886	my $idx;
		887	$PROTOCOL{$_} = ++$idx
		888	for reverse split /\s*,\s*/,
		889	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		890	}
669		891
670	my @models = (	892	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	893	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	894	[Event:: => AnyEvent::Impl::Event::],
675	[Tk:: => AnyEvent::Impl::Tk::],
676	[Wx:: => AnyEvent::Impl::POE::],
677	[Prima:: => AnyEvent::Impl::POE::],
678	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	896	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	897	# as the pureperl backend should work everywhere
		898	# and is usually faster
		899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		904	[Wx:: => AnyEvent::Impl::POE::],
		905	[Prima:: => AnyEvent::Impl::POE::],
684	);	906	);
685		907
686	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		909
		910	our @post_detect;
		911
		912	sub post_detect(&) {
		913	my ($cb) = @_;
		914
		915	if ($MODEL) {
		916	$cb->();
		917
		918	1
		919	} else {
		920	push @post_detect, $cb;
		921
		922	defined wantarray
		923	? bless \$cb, "AnyEvent::Util::PostDetect"
		924	: ()
		925	}
		926	}
		927
		928	sub AnyEvent::Util::PostDetect::DESTROY {
		929	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		930	}
687		931
688	sub detect() {	932	sub detect() {
689	unless ($MODEL) {	933	unless ($MODEL) {
690	no strict 'refs';	934	no strict 'refs';
		935	local $SIG{__DIE__};
691		936
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	938	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	939	if (eval "require $model") {
695	$MODEL = $model;	940	$MODEL = $model;
…		…
725	last;	970	last;
726	}	971	}
727	}	972	}
728		973
729	$MODEL	974	$MODEL
730	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
731	}	976	}
732	}	977	}
733		978
		979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		980
734	unshift @ISA, $MODEL;	981	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	982
		983	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		984
		985	(shift @post_detect)->() while @post_detect;
736	}	986	}
737		987
738	$MODEL	988	$MODEL
739	}	989	}
740		990
…		…
748		998
749	my $class = shift;	999	my $class = shift;
750	$class->$func (@_);	1000	$class->$func (@_);
751	}	1001	}
752		1002
		1003	# utility function to dup a filehandle. this is used by many backends
		1004	# to support binding more than one watcher per filehandle (they usually
		1005	# allow only one watcher per fd, so we dup it to get a different one).
		1006	sub _dupfh($$$$) {
		1007	my ($poll, $fh, $r, $w) = @_;
		1008
		1009	require Fcntl;
		1010
		1011	# cygwin requires the fh mode to be matching, unix doesn't
		1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1013	: $poll eq "w" ? ($w, ">")
		1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1015
		1016	open my $fh2, "$mode&" . fileno $fh
		1017	or die "cannot dup() filehandle: $!";
		1018
		1019	# we assume CLOEXEC is already set by perl in all important cases
		1020
		1021	($fh2, $rw)
		1022	}
		1023
753	package AnyEvent::Base;	1024	package AnyEvent::Base;
754		1025
		1026	# default implementation for now and time
		1027
		1028	BEGIN {
		1029	if (eval "use Time::HiRes (); time (); 1") {
		1030	*_time = \&Time::HiRes::time;
		1031	# if (eval "use POSIX (); (POSIX::times())...
		1032	} else {
		1033	*_time = \&CORE::time; # epic fail
		1034	}
		1035	}
		1036
		1037	sub time { _time }
		1038	sub now { _time }
		1039
755	# default implementation for ->condvar, ->wait, ->broadcast	1040	# default implementation for ->condvar
756		1041
757	sub condvar {	1042	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
759	}
760
761	sub AnyEvent::Base::CondVar::broadcast {
762	${$_[0]}++;
763	}
764
765	sub AnyEvent::Base::CondVar::wait {
766	AnyEvent->one_event while !${$_[0]};
767	}	1044	}
768		1045
769	# default implementation for ->signal	1046	# default implementation for ->signal
770		1047
771	our %SIG_CB;	1048	our %SIG_CB;
…		…
787	sub AnyEvent::Base::Signal::DESTROY {	1064	sub AnyEvent::Base::Signal::DESTROY {
788	my ($signal, $cb) = @{$_[0]};	1065	my ($signal, $cb) = @{$_[0]};
789		1066
790	delete $SIG_CB{$signal}{$cb};	1067	delete $SIG_CB{$signal}{$cb};
791		1068
792	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
793	}	1070	}
794		1071
795	# default implementation for ->child	1072	# default implementation for ->child
796		1073
797	our %PID_CB;	1074	our %PID_CB;
…		…
824	or Carp::croak "required option 'pid' is missing";	1101	or Carp::croak "required option 'pid' is missing";
825		1102
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1104
828	unless ($WNOHANG) {	1105	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
830	}	1107	}
831		1108
832	unless ($CHLD_W) {	1109	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# child could be a zombie already, so make at least one round	1111	# child could be a zombie already, so make at least one round
…		…
844	delete $PID_CB{$pid}{$cb};	1121	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1122	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1123
847	undef $CHLD_W unless keys %PID_CB;	1124	undef $CHLD_W unless keys %PID_CB;
848	}	1125	}
		1126
		1127	package AnyEvent::CondVar;
		1128
		1129	our @ISA = AnyEvent::CondVar::Base::;
		1130
		1131	package AnyEvent::CondVar::Base;
		1132
		1133	use overload
		1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1135	fallback => 1;
		1136
		1137	sub _send {
		1138	# nop
		1139	}
		1140
		1141	sub send {
		1142	my $cv = shift;
		1143	$cv->{_ae_sent} = [@_];
		1144	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1145	$cv->_send;
		1146	}
		1147
		1148	sub croak {
		1149	$_[0]{_ae_croak} = $_[1];
		1150	$_[0]->send;
		1151	}
		1152
		1153	sub ready {
		1154	$_[0]{_ae_sent}
		1155	}
		1156
		1157	sub _wait {
		1158	AnyEvent->one_event while !$_[0]{_ae_sent};
		1159	}
		1160
		1161	sub recv {
		1162	$_[0]->_wait;
		1163
		1164	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1165	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1166	}
		1167
		1168	sub cb {
		1169	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1170	$_[0]{_ae_cb}
		1171	}
		1172
		1173	sub begin {
		1174	++$_[0]{_ae_counter};
		1175	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1176	}
		1177
		1178	sub end {
		1179	return if --$_[0]{_ae_counter};
		1180	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1181	}
		1182
		1183	# undocumented/compatibility with pre-3.4
		1184	*broadcast = \&send;
		1185	*wait = \&_wait;
		1186
		1187	=head1 ERROR AND EXCEPTION HANDLING
		1188
		1189	In general, AnyEvent does not do any error handling - it relies on the
		1190	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1191	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1192	checking of all AnyEvent methods, however, which is highly useful during
		1193	development.
		1194
		1195	As for exception handling (i.e. runtime errors and exceptions thrown while
		1196	executing a callback), this is not only highly event-loop specific, but
		1197	also not in any way wrapped by this module, as this is the job of the main
		1198	program.
		1199
		1200	The pure perl event loop simply re-throws the exception (usually
		1201	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1202	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1203	so on.
		1204
		1205	=head1 ENVIRONMENT VARIABLES
		1206
		1207	The following environment variables are used by this module or its
		1208	submodules:
		1209
		1210	=over 4
		1211
		1212	=item C<PERL_ANYEVENT_VERBOSE>
		1213
		1214	By default, AnyEvent will be completely silent except in fatal
		1215	conditions. You can set this environment variable to make AnyEvent more
		1216	talkative.
		1217
		1218	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1219	conditions, such as not being able to load the event model specified by
		1220	C<PERL_ANYEVENT_MODEL>.
		1221
		1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1223	model it chooses.
		1224
		1225	=item C<PERL_ANYEVENT_STRICT>
		1226
		1227	AnyEvent does not do much argument checking by default, as thorough
		1228	argument checking is very costly. Setting this variable to a true value
		1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1230	check the arguments passed to most method calls. If it finds any problems
		1231	it will croak.
		1232
		1233	In other words, enables "strict" mode.
		1234
		1235	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1237	developing programs can be very useful, however.
		1238
		1239	=item C<PERL_ANYEVENT_MODEL>
		1240
		1241	This can be used to specify the event model to be used by AnyEvent, before
		1242	auto detection and -probing kicks in. It must be a string consisting
		1243	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1244	and the resulting module name is loaded and if the load was successful,
		1245	used as event model. If it fails to load AnyEvent will proceed with
		1246	auto detection and -probing.
		1247
		1248	This functionality might change in future versions.
		1249
		1250	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1251	could start your program like this:
		1252
		1253	PERL_ANYEVENT_MODEL=Perl perl ...
		1254
		1255	=item C<PERL_ANYEVENT_PROTOCOLS>
		1256
		1257	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1258	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1259	of auto probing).
		1260
		1261	Must be set to a comma-separated list of protocols or address families,
		1262	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1263	used, and preference will be given to protocols mentioned earlier in the
		1264	list.
		1265
		1266	This variable can effectively be used for denial-of-service attacks
		1267	against local programs (e.g. when setuid), although the impact is likely
		1268	small, as the program has to handle connection errors already-
		1269
		1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1272	- only support IPv4, never try to resolve or contact IPv6
		1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1274	IPv6, but prefer IPv6 over IPv4.
		1275
		1276	=item C<PERL_ANYEVENT_EDNS0>
		1277
		1278	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1279	for DNS. This extension is generally useful to reduce DNS traffic, but
		1280	some (broken) firewalls drop such DNS packets, which is why it is off by
		1281	default.
		1282
		1283	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1284	EDNS0 in its DNS requests.
		1285
		1286	=item C<PERL_ANYEVENT_MAX_FORKS>
		1287
		1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1289	will create in parallel.
		1290
		1291	=back
849		1292
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1294
852	This is an advanced topic that you do not normally need to use AnyEvent in	1295	This is an advanced topic that you do not normally need to use AnyEvent in
853	a module. This section is only of use to event loop authors who want to	1296	a module. This section is only of use to event loop authors who want to
…		…
887		1330
888	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1331	I<rxvt-unicode> also cheats a bit by not providing blocking access to
889	condition variables: code blocking while waiting for a condition will	1332	condition variables: code blocking while waiting for a condition will
890	C<die>. This still works with most modules/usages, and blocking calls must	1333	C<die>. This still works with most modules/usages, and blocking calls must
891	not be done in an interactive application, so it makes sense.	1334	not be done in an interactive application, so it makes sense.
892
893	=head1 ENVIRONMENT VARIABLES
894
895	The following environment variables are used by this module:
896
897	=over 4
898
899	=item C<PERL_ANYEVENT_VERBOSE>
900
901	By default, AnyEvent will be completely silent except in fatal
902	conditions. You can set this environment variable to make AnyEvent more
903	talkative.
904
905	When set to C<1> or higher, causes AnyEvent to warn about unexpected
906	conditions, such as not being able to load the event model specified by
907	C<PERL_ANYEVENT_MODEL>.
908
909	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
910	model it chooses.
911
912	=item C<PERL_ANYEVENT_MODEL>
913
914	This can be used to specify the event model to be used by AnyEvent, before
915	autodetection and -probing kicks in. It must be a string consisting
916	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
917	and the resulting module name is loaded and if the load was successful,
918	used as event model. If it fails to load AnyEvent will proceed with
919	autodetection and -probing.
920
921	This functionality might change in future versions.
922
923	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
924	could start your program like this:
925
926	PERL_ANYEVENT_MODEL=Perl perl ...
927
928	=back
929		1335
930	=head1 EXAMPLE PROGRAM	1336	=head1 EXAMPLE PROGRAM
931		1337
932	The following program uses an I/O watcher to read data from STDIN, a timer	1338	The following program uses an I/O watcher to read data from STDIN, a timer
933	to display a message once per second, and a condition variable to quit the	1339	to display a message once per second, and a condition variable to quit the
…		…
942	poll => 'r',	1348	poll => 'r',
943	cb => sub {	1349	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1350	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1351	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1352	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1353	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1354	},
949	);	1355	);
950		1356
951	my $time_watcher; # can only be used once	1357	my $time_watcher; # can only be used once
952		1358
…		…
957	});	1363	});
958	}	1364	}
959		1365
960	new_timer; # create first timer	1366	new_timer; # create first timer
961		1367
962	$cv->wait; # wait until user enters /^q/i	1368	$cv->recv; # wait until user enters /^q/i
963		1369
964	=head1 REAL-WORLD EXAMPLE	1370	=head1 REAL-WORLD EXAMPLE
965		1371
966	Consider the L<Net::FCP> module. It features (among others) the following	1372	Consider the L<Net::FCP> module. It features (among others) the following
967	API calls, which are to freenet what HTTP GET requests are to http:	1373	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1423	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1424	or die "connection or write error";
1019	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1425	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020		1426
1021	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1427	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1022	result and signals any possible waiters that the request ahs finished:	1428	result and signals any possible waiters that the request has finished:
1023		1429
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1430	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1431
1026	if (end-of-file or data complete) {	1432	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1433	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1434	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1435	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1436	}
1031		1437
1032	The C<result> method, finally, just waits for the finished signal (if the	1438	The C<result> method, finally, just waits for the finished signal (if the
1033	request was already finished, it doesn't wait, of course, and returns the	1439	request was already finished, it doesn't wait, of course, and returns the
1034	data:	1440	data:
1035		1441
1036	$txn->{finished}->wait;	1442	$txn->{finished}->recv;
1037	return $txn->{result};	1443	return $txn->{result};
1038		1444
1039	The actual code goes further and collects all errors (C<die>s, exceptions)	1445	The actual code goes further and collects all errors (C<die>s, exceptions)
1040	that occured during request processing. The C<result> method detects	1446	that occurred during request processing. The C<result> method detects
1041	whether an exception as thrown (it is stored inside the $txn object)	1447	whether an exception as thrown (it is stored inside the $txn object)
1042	and just throws the exception, which means connection errors and other	1448	and just throws the exception, which means connection errors and other
1043	problems get reported tot he code that tries to use the result, not in a	1449	problems get reported tot he code that tries to use the result, not in a
1044	random callback.	1450	random callback.
1045		1451
…		…
1076		1482
1077	my $quit = AnyEvent->condvar;	1483	my $quit = AnyEvent->condvar;
1078		1484
1079	$fcp->txn_client_get ($url)->cb (sub {	1485	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1486	...
1081	$quit->broadcast;	1487	$quit->send;
1082	});	1488	});
1083		1489
1084	$quit->wait;	1490	$quit->recv;
1085		1491
1086		1492
1087	=head1 BENCHMARKS	1493	=head1 BENCHMARKS
1088		1494
1089	To give you an idea of the performance and overheads that AnyEvent adds	1495	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1091	of various event loops I prepared some benchmarks.	1497	of various event loops I prepared some benchmarks.
1092		1498
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1499	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1500
1095	Here is a benchmark of various supported event models used natively and	1501	Here is a benchmark of various supported event models used natively and
1096	through anyevent. The benchmark creates a lot of timers (with a zero	1502	through AnyEvent. The benchmark creates a lot of timers (with a zero
1097	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1503	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1098	which it is), lets them fire exactly once and destroys them again.	1504	which it is), lets them fire exactly once and destroys them again.
1099		1505
1100	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1506	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101	distribution.	1507	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1524	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1525	and memory usage is not included in the figures.
1120		1526
1121	I<invoke> is the time, in microseconds, used to invoke a simple	1527	I<invoke> is the time, in microseconds, used to invoke a simple
1122	callback. The callback simply counts down a Perl variable and after it was	1528	callback. The callback simply counts down a Perl variable and after it was
1123	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1529	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1530	signal the end of this phase.
1125		1531
1126	I<destroy> is the time, in microseconds, that it takes to destroy a single	1532	I<destroy> is the time, in microseconds, that it takes to destroy a single
1127	watcher.	1533	watcher.
1128		1534
…		…
1224		1630
1225	=back	1631	=back
1226		1632
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1633	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1634
1229	This benchmark atcually benchmarks the event loop itself. It works by	1635	This benchmark actually benchmarks the event loop itself. It works by
1230	creating a number of "servers": each server consists of a socketpair, a	1636	creating a number of "servers": each server consists of a socket pair, a
1231	timeout watcher that gets reset on activity (but never fires), and an I/O	1637	timeout watcher that gets reset on activity (but never fires), and an I/O
1232	watcher waiting for input on one side of the socket. Each time the socket	1638	watcher waiting for input on one side of the socket. Each time the socket
1233	watcher reads a byte it will write that byte to a random other "server".	1639	watcher reads a byte it will write that byte to a random other "server".
1234		1640
1235	The effect is that there will be a lot of I/O watchers, only part of which	1641	The effect is that there will be a lot of I/O watchers, only part of which
1236	are active at any one point (so there is a constant number of active	1642	are active at any one point (so there is a constant number of active
1237	fds for each loop iterstaion, but which fds these are is random). The	1643	fds for each loop iteration, but which fds these are is random). The
1238	timeout is reset each time something is read because that reflects how	1644	timeout is reset each time something is read because that reflects how
1239	most timeouts work (and puts extra pressure on the event loops).	1645	most timeouts work (and puts extra pressure on the event loops).
1240		1646
1241	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1647	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1242	(1%) are active. This mirrors the activity of large servers with many	1648	(1%) are active. This mirrors the activity of large servers with many
1243	connections, most of which are idle at any one point in time.	1649	connections, most of which are idle at any one point in time.
1244		1650
1245	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1651	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246	distribution.	1652	distribution.
…		…
1248	=head3 Explanation of the columns	1654	=head3 Explanation of the columns
1249		1655
1250	I<sockets> is the number of sockets, and twice the number of "servers" (as	1656	I<sockets> is the number of sockets, and twice the number of "servers" (as
1251	each server has a read and write socket end).	1657	each server has a read and write socket end).
1252		1658
1253	I<create> is the time it takes to create a socketpair (which is	1659	I<create> is the time it takes to create a socket pair (which is
1254	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1660	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255		1661
1256	I<request>, the most important value, is the time it takes to handle a	1662	I<request>, the most important value, is the time it takes to handle a
1257	single "request", that is, reading the token from the pipe and forwarding	1663	single "request", that is, reading the token from the pipe and forwarding
1258	it to another server. This includes deleting the old timeout and creating	1664	it to another server. This includes deleting the old timeout and creating
…		…
1331	speed most when you have lots of watchers, not when you only have a few of	1737	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1738	them).
1333		1739
1334	EV is again fastest.	1740	EV is again fastest.
1335		1741
1336	Perl again comes second. It is noticably faster than the C-based event	1742	Perl again comes second. It is noticeably faster than the C-based event
1337	loops Event and Glib, although the difference is too small to really	1743	loops Event and Glib, although the difference is too small to really
1338	matter.	1744	matter.
1339		1745
1340	POE also performs much better in this case, but is is still far behind the	1746	POE also performs much better in this case, but is is still far behind the
1341	others.	1747	others.
…		…
1370	specified in the variable.	1776	specified in the variable.
1371		1777
1372	You can make AnyEvent completely ignore this variable by deleting it	1778	You can make AnyEvent completely ignore this variable by deleting it
1373	before the first watcher gets created, e.g. with a C<BEGIN> block:	1779	before the first watcher gets created, e.g. with a C<BEGIN> block:
1374		1780
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1781	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		1782
1377	use AnyEvent;	1783	use AnyEvent;
		1784
		1785	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1786	be used to probe what backend is used and gain other information (which is
		1787	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1788	$ENV{PERL_ANYEGENT_STRICT}.
		1789
		1790
		1791	=head1 BUGS
		1792
		1793	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1794	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1795	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1796	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1797	pronounced).
1378		1798
1379		1799
1380	=head1 SEE ALSO	1800	=head1 SEE ALSO
1381		1801
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1802	Utility functions: L<AnyEvent::Util>.
1383	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1803
		1804	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	1805	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		1806
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1807	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1808	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1388	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1809	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1810	L<AnyEvent::Impl::POE>.
1390		1811
		1812	Non-blocking file handles, sockets, TCP clients and
		1813	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1814
		1815	Asynchronous DNS: L<AnyEvent::DNS>.
		1816
		1817	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1818
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1819	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		1820
1393		1821
1394	=head1 AUTHOR	1822	=head1 AUTHOR
1395		1823
1396	Marc Lehmann <schmorp@schmorp.de>	1824	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	1825	http://home.schmorp.de/
1398		1826
1399	=cut	1827	=cut
1400		1828
1401	1	1829	1
1402		1830

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