ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.105 by root, Thu May 1 12:35:54 2008 UTC vs.
Revision 1.226 by root, Mon Jul 6 23:32:49 2009 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 and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	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	55	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,	56	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,	57	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	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	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	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	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	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	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	69	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	70	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	71	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	72	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.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	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	77	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,	78	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	79	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	80	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	81	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).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	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	85	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	86	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	87	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	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	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	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
78	The interface itself is vaguely similar, but not identical to the L<Event>	108	The interface itself is vaguely similar, but not identical to the L<Event>
79	module.	109	module.
80		110
81	During the first call of any watcher-creation method, the module tries	111	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	112	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>,	113	following modules is already loaded: L<EV>,
84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	114	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	115	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	116	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	117	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	118	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	132	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...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	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	142	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
114		144
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	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	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	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	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	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	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	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	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	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	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
242	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	362	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.	363	but it is guaranteed not to interrupt any other callbacks.
246		364
247	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	366	between multiple watchers.
249		367
250	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
260		378
261	The child process is specified by the C<pid> argument (if set to C<0>, it	379	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	380	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	381	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	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	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	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
272	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
275		403
276	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
279		408
280	Example: fork a process and wait for it	409	Example: fork a process and wait for it
281		410
282	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
283		412
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
287		414
288	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
289	pid => $pid,	416	pid => $pid,
290	cb => sub {	417	cb => sub {
291	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
293	$done->broadcast;	420	$done->send;
294	},	421	},
295	);	422	);
296		423
297	# do something else, then wait for process exit	424	# do something else, then wait for process exit
298	$done->wait;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
299		461
300	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
301		463
302	If you are familiar with some event loops you will know that all of them	464	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	465	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	471	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	472	because they represent a condition that must become true.
311		473
312	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
314	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
316		480
317	After creation, the conditon variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	482	by calling the C<send> method (or calling the condition variable as if it
		483	were a callback, read about the caveats in the description for the C<<
		484	->send >> method).
319		485
320	Condition variables are similar to callbacks, except that you can	486	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	487	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	488	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	489	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	490	used to represent a transaction, which finishes at some point and delivers
325	a result.	491	a result.
326		492
327	Condition variables are very useful to signal that something has finished,	493	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	494	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	495	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	496	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	497	called or can synchronously C<< ->recv >> for the results.
332		498
333	You can also use them to simulate traditional event loops - for example,	499	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	500	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	501	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.	502	button of your app, which would C<< ->send >> the "quit" event.
337		503
338	Note that condition variables recurse into the event loop - if you have	504	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	505	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	506	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,	507	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	508	as this asks for trouble.
343		509
344	Condition variables are represented by hash refs in perl, and the keys	510	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	512	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	513	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	514	it's C<new> method in your own C<new> method.
349		515
350	There are two "sides" to a condition variable - the "producer side" which	516	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	517	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	518	for the send to occur.
353		519
354	Example:	520	Example: wait for a timer.
355		521
356	# wait till the result is ready	522	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	523	my $result_ready = AnyEvent->condvar;
358		524
359	# do something such as adding a timer	525	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	526	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	527	# when the "result" is ready.
362	# in this case, we simply use a timer:	528	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	529	my $w = AnyEvent->timer (
364	after => 1,	530	after => 1,
365	cb => sub { $result_ready->broadcast },	531	cb => sub { $result_ready->send },
366	);	532	);
367		533
368	# this "blocks" (while handling events) till the callback	534	# this "blocks" (while handling events) till the callback
369	# calls broadcast	535	# calls send
370	$result_ready->wait;	536	$result_ready->recv;
		537
		538	Example: wait for a timer, but take advantage of the fact that
		539	condition variables are also code references.
		540
		541	my $done = AnyEvent->condvar;
		542	my $delay = AnyEvent->timer (after => 5, cb => $done);
		543	$done->recv;
		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
371		561
372	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
373		563
374	These methods should only be used by the producing side, i.e. the	564	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	565	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	566	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	567	uncommon for the consumer to create it as well.
378		568
379	=over 4	569	=over 4
380		570
381	=item $cv->broadcast (...)	571	=item $cv->send (...)
382		572
383	Flag the condition as ready - a running C<< ->wait >> and all further	573	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	574	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	575	called. If nobody is waiting the send will be remembered.
386		576
387	If a callback has been set on the condition variable, it is called	577	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	578	immediately from within send.
389		579
390	Any arguments passed to the C<broadcast> call will be returned by all	580	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	581	future C<< ->recv >> calls.
		582
		583	Condition variables are overloaded so one can call them directly
		584	(as a code reference). Calling them directly is the same as calling
		585	C<send>. Note, however, that many C-based event loops do not handle
		586	overloading, so as tempting as it may be, passing a condition variable
		587	instead of a callback does not work. Both the pure perl and EV loops
		588	support overloading, however, as well as all functions that use perl to
		589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		590	example).
392		591
393	=item $cv->croak ($error)	592	=item $cv->croak ($error)
394		593
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	594	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	595	C<Carp::croak> with the given error message/object/scalar.
397		596
398	This can be used to signal any errors to the condition variable	597	This can be used to signal any errors to the condition variable
399	user/consumer.	598	user/consumer.
400		599
…		…
407	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
408		607
409	Every call to C<< ->begin >> will increment a counter, and every call to	608	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	609	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	610	>>, 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	611	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.	612	callback was set, C<send> will be called without any arguments.
414		613
415	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
416		621
417	my $cv = AnyEvent->condvar;	622	my $cv = AnyEvent->condvar;
418		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
		645
		646	my $cv = AnyEvent->condvar;
		647
419	my %result;	648	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
421		650
422	for my $host (@list_of_hosts) {	651	for my $host (@list_of_hosts) {
423	$cv->begin;	652	$cv->begin;
424	ping_host_then_call_callback $host, sub {	653	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	654	$result{$host} = ...;
…		…
428	}	657	}
429		658
430	$cv->end;	659	$cv->end;
431		660
432	This code fragment supposedly pings a number of hosts and calls	661	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	662	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	663	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	664	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	665	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	666	results arrive is not relevant.
438		667
439	There is an additional bracketing call to C<begin> and C<end> outside the	668	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	669	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	670	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	671	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	672	doesn't execute once).
444		673
445	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
447	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
448	C<begin> and for eahc subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
449		679
450	=back	680	=back
451		681
452	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
453		683
454	These methods should only be used by the consuming side, i.e. the	684	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	685	code awaits the condition.
456		686
457	=item $cv->wait	687	=over 4
458		688
		689	=item $cv->recv
		690
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	691	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	692	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	693	normally.
462		694
463	You can only wait once on a condition - additional calls are valid but	695	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	696	will return immediately.
465		697
466	If an error condition has been set by calling C<< ->croak >>, then this	698	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	699	function will call C<croak>.
468		700
469	In list context, all parameters passed to C<broadcast> will be returned,	701	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	702	in scalar context only the first one will be returned.
471		703
472	Not all event models support a blocking wait - some die in that case	704	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	705	(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	706	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	707	caller decide whether the call will block or not (for example, by coupling
476	condition variables with some kind of request results and supporting	708	condition variables with some kind of request results and supporting
477	callbacks so the caller knows that getting the result will not block,	709	callbacks so the caller knows that getting the result will not block,
478	while still suppporting blocking waits if the caller so desires).	710	while still supporting blocking waits if the caller so desires).
479		711
480	Another reason I<never> to C<< ->wait >> in a module is that you cannot	712	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	713	sensibly have two C<< ->recv >>'s in parallel, as that would require
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	714	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	715	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		716
		717	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		718	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		719	versions and also integrates coroutines into AnyEvent, making blocking
		720	C<< ->recv >> calls perfectly safe as long as they are done from another
		721	coroutine (one that doesn't run the event loop).
		722
487	You can ensure that C<< -wait >> never blocks by setting a callback and	723	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	724	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	725	time). This will work even when the event loop does not support blocking
490	waits otherwise.	726	waits otherwise.
		727
		728	=item $bool = $cv->ready
		729
		730	Returns true when the condition is "true", i.e. whether C<send> or
		731	C<croak> have been called.
		732
		733	=item $cb = $cv->cb ($cb->($cv))
		734
		735	This is a mutator function that returns the callback set and optionally
		736	replaces it before doing so.
		737
		738	The callback will be called when the condition becomes "true", i.e. when
		739	C<send> or C<croak> are called, with the only argument being the condition
		740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
491		742
492	=back	743	=back
493		744
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	745	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		746
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	754	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>).	755	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		756
506	The known classes so far are:	757	The known classes so far are:
507		758
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).	759	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	760	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	761	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	762	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	763	AnyEvent::Impl::Tk based on Tk, very bad choice.
515	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
516	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
517	AnyEvent::Impl::POE based on POE, not generic enough for full support.	766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
518		767
		768	# warning, support for IO::Async is only partial, as it is too broken
		769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		771
519	There is no support for WxWidgets, as WxWidgets has no support for	772	There is no support for WxWidgets, as WxWidgets has no support for
520	watching file handles. However, you can use WxWidgets through the	773	watching file handles. However, you can use WxWidgets through the
521	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
522	second, which was considered to be too horrible to even consider for	775	second, which was considered to be too horrible to even consider for
523	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	784	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	if necessary. You should only call this function right before you would	785	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	786	have created an AnyEvent watcher anyway, that is, as late as possible at
534	runtime.	787	runtime.
535		788
		789	=item $guard = AnyEvent::post_detect { BLOCK }
		790
		791	Arranges for the code block to be executed as soon as the event model is
		792	autodetected (or immediately if this has already happened).
		793
		794	If called in scalar or list context, then it creates and returns an object
		795	that automatically removes the callback again when it is destroyed. See
		796	L<Coro::BDB> for a case where this is useful.
		797
		798	=item @AnyEvent::post_detect
		799
		800	If there are any code references in this array (you can C<push> to it
		801	before or after loading AnyEvent), then they will called directly after
		802	the event loop has been chosen.
		803
		804	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		805	if it contains a true value then the event loop has already been detected,
		806	and the array will be ignored.
		807
		808	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		809
536	=back	810	=back
537		811
538	=head1 WHAT TO DO IN A MODULE	812	=head1 WHAT TO DO IN A MODULE
539		813
540	As a module author, you should C<use AnyEvent> and call AnyEvent methods	814	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	817	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	818	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	819	by calling AnyEvent in your module body you force the user of your module
546	to load the event module first.	820	to load the event module first.
547		821
548	Never call C<< ->wait >> on a condition variable unless you I<know> that	822	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	823	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	824	because it will stall the whole program, and the whole point of using
551	events is to stay interactive.	825	events is to stay interactive.
552		826
553	It is fine, however, to call C<< ->wait >> when the user of your module	827	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	828	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 >>	829	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).	830	freely, as the user of your module knows what she is doing. always).
557		831
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	832	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		833
560	There will always be a single main program - the only place that should	834	There will always be a single main program - the only place that should
…		…
562		836
563	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	837	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	838	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.	839	decide which implementation to chose if some module relies on it.
566		840
567	If the main program relies on a specific event model. For example, in	841	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	842	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	843	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	844	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	845	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	846	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.	847	might chose the wrong one unless you load the correct one yourself.
574		848
575	You can chose to use a rather inefficient pure-perl implementation by	849	You can chose to use a pure-perl implementation by loading the
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	850	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	behaviour everywhere, but letting AnyEvent chose is generally better.	851	everywhere, but letting AnyEvent chose the model is generally better.
		852
		853	=head2 MAINLOOP EMULATION
		854
		855	Sometimes (often for short test scripts, or even standalone programs who
		856	only want to use AnyEvent), you do not want to run a specific event loop.
		857
		858	In that case, you can use a condition variable like this:
		859
		860	AnyEvent->condvar->recv;
		861
		862	This has the effect of entering the event loop and looping forever.
		863
		864	Note that usually your program has some exit condition, in which case
		865	it is better to use the "traditional" approach of storing a condition
		866	variable somewhere, waiting for it, and sending it when the program should
		867	exit cleanly.
		868
578		869
579	=head1 OTHER MODULES	870	=head1 OTHER MODULES
580		871
581	The following is a non-exhaustive list of additional modules that use	872	The following is a non-exhaustive list of additional modules that use
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	873	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
588	=item L<AnyEvent::Util>	879	=item L<AnyEvent::Util>
589		880
590	Contains various utility functions that replace often-used but blocking	881	Contains various utility functions that replace often-used but blocking
591	functions such as C<inet_aton> by event-/callback-based versions.	882	functions such as C<inet_aton> by event-/callback-based versions.
592		883
		884	=item L<AnyEvent::Socket>
		885
		886	Provides various utility functions for (internet protocol) sockets,
		887	addresses and name resolution. Also functions to create non-blocking tcp
		888	connections or tcp servers, with IPv6 and SRV record support and more.
		889
593	=item L<AnyEvent::Handle>	890	=item L<AnyEvent::Handle>
594		891
595	Provide read and write buffers and manages watchers for reads and writes.	892	Provide read and write buffers, manages watchers for reads and writes,
		893	supports raw and formatted I/O, I/O queued and fully transparent and
		894	non-blocking SSL/TLS.
596		895
597	=item L<AnyEvent::Socket>	896	=item L<AnyEvent::DNS>
598		897
599	Provides a means to do non-blocking connects, accepts etc.	898	Provides rich asynchronous DNS resolver capabilities.
		899
		900	=item L<AnyEvent::HTTP>
		901
		902	A simple-to-use HTTP library that is capable of making a lot of concurrent
		903	HTTP requests.
600		904
601	=item L<AnyEvent::HTTPD>	905	=item L<AnyEvent::HTTPD>
602		906
603	Provides a simple web application server framework.	907	Provides a simple web application server framework.
604		908
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>	909	=item L<AnyEvent::FastPing>
611		910
612	The fastest ping in the west.	911	The fastest ping in the west.
613		912
		913	=item L<AnyEvent::DBI>
		914
		915	Executes L<DBI> requests asynchronously in a proxy process.
		916
		917	=item L<AnyEvent::AIO>
		918
		919	Truly asynchronous I/O, should be in the toolbox of every event
		920	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		921	together.
		922
		923	=item L<AnyEvent::BDB>
		924
		925	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		926	L<BDB> and AnyEvent together.
		927
		928	=item L<AnyEvent::GPSD>
		929
		930	A non-blocking interface to gpsd, a daemon delivering GPS information.
		931
		932	=item L<AnyEvent::IGS>
		933
		934	A non-blocking interface to the Internet Go Server protocol (used by
		935	L<App::IGS>).
		936
614	=item L<Net::IRC3>	937	=item L<AnyEvent::IRC>
615		938
616	AnyEvent based IRC client module family.	939	AnyEvent based IRC client module family (replacing the older Net::IRC3).
617		940
618	=item L<Net::XMPP2>	941	=item L<Net::XMPP2>
619		942
620	AnyEvent based XMPP (Jabber protocol) module family.	943	AnyEvent based XMPP (Jabber protocol) module family.
621		944
…		…
628		951
629	High level API for event-based execution flow control.	952	High level API for event-based execution flow control.
630		953
631	=item L<Coro>	954	=item L<Coro>
632		955
633	Has special support for AnyEvent.	956	Has special support for AnyEvent via L<Coro::AnyEvent>.
634		957
635	=item L<IO::Lambda>	958	=item L<IO::Lambda>
636		959
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	960	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638		961
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	962	=back
650		963
651	=cut	964	=cut
652		965
653	package AnyEvent;	966	package AnyEvent;
654		967
655	no warnings;	968	no warnings;
656	use strict;	969	use strict qw(vars subs);
657		970
658	use Carp;	971	use Carp;
659		972
660	our $VERSION = '3.3';	973	our $VERSION = 4.8;
661	our $MODEL;	974	our $MODEL;
662		975
663	our $AUTOLOAD;	976	our $AUTOLOAD;
664	our @ISA;	977	our @ISA;
665		978
		979	our @REGISTRY;
		980
		981	our $WIN32;
		982
		983	BEGIN {
		984	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		985	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		986
		987	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		988	if ${^TAINT};
		989	}
		990
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	991	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		992
668	our @REGISTRY;	993	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		994
		995	{
		996	my $idx;
		997	$PROTOCOL{$_} = ++$idx
		998	for reverse split /\s*,\s*/,
		999	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1000	}
669		1001
670	my @models = (	1002	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	1003	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	1004	[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::],	1005	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1006	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	1007	# as the pureperl backend should work everywhere
		1008	# and is usually faster
		1009	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1010	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1011	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1012	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1013	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		1014	[Wx:: => AnyEvent::Impl::POE::],
		1015	[Prima:: => AnyEvent::Impl::POE::],
		1016	# IO::Async is just too broken - we would need workaorunds for its
		1017	# byzantine signal and broken child handling, among others.
		1018	# IO::Async is rather hard to detect, as it doesn't have any
		1019	# obvious default class.
		1020	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1021	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1022	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
684	);	1023	);
685		1024
686	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1025	our %method = map +($_ => 1),
		1026	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1027
		1028	our @post_detect;
		1029
		1030	sub post_detect(&) {
		1031	my ($cb) = @_;
		1032
		1033	if ($MODEL) {
		1034	$cb->();
		1035
		1036	1
		1037	} else {
		1038	push @post_detect, $cb;
		1039
		1040	defined wantarray
		1041	? bless \$cb, "AnyEvent::Util::postdetect"
		1042	: ()
		1043	}
		1044	}
		1045
		1046	sub AnyEvent::Util::postdetect::DESTROY {
		1047	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1048	}
687		1049
688	sub detect() {	1050	sub detect() {
689	unless ($MODEL) {	1051	unless ($MODEL) {
690	no strict 'refs';	1052	no strict 'refs';
		1053	local $SIG{__DIE__};
691		1054
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1055	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	1056	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	1057	if (eval "require $model") {
695	$MODEL = $model;	1058	$MODEL = $model;
…		…
725	last;	1088	last;
726	}	1089	}
727	}	1090	}
728		1091
729	$MODEL	1092	$MODEL
730	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1093	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
731	}	1094	}
732	}	1095	}
733		1096
		1097	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1098
734	unshift @ISA, $MODEL;	1099	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1100
		1101	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1102
		1103	(shift @post_detect)->() while @post_detect;
736	}	1104	}
737		1105
738	$MODEL	1106	$MODEL
739	}	1107	}
740		1108
…		…
748		1116
749	my $class = shift;	1117	my $class = shift;
750	$class->$func (@_);	1118	$class->$func (@_);
751	}	1119	}
752		1120
		1121	# utility function to dup a filehandle. this is used by many backends
		1122	# to support binding more than one watcher per filehandle (they usually
		1123	# allow only one watcher per fd, so we dup it to get a different one).
		1124	sub _dupfh($$;$$) {
		1125	my ($poll, $fh, $r, $w) = @_;
		1126
		1127	# cygwin requires the fh mode to be matching, unix doesn't
		1128	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1129	: $poll eq "w" ? ($w, ">")
		1130	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1131
		1132	open my $fh2, "$mode&" . fileno $fh
		1133	or die "cannot dup() filehandle: $!,";
		1134
		1135	# we assume CLOEXEC is already set by perl in all important cases
		1136
		1137	($fh2, $rw)
		1138	}
		1139
753	package AnyEvent::Base;	1140	package AnyEvent::Base;
754		1141
		1142	# default implementations for many methods
		1143
		1144	BEGIN {
		1145	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1146	*_time = \&Time::HiRes::time;
		1147	# if (eval "use POSIX (); (POSIX::times())...
		1148	} else {
		1149	*_time = sub { time }; # epic fail
		1150	}
		1151	}
		1152
		1153	sub time { _time }
		1154	sub now { _time }
		1155	sub now_update { }
		1156
755	# default implementation for ->condvar, ->wait, ->broadcast	1157	# default implementation for ->condvar
756		1158
757	sub condvar {	1159	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	1160	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	}	1161	}
768		1162
769	# default implementation for ->signal	1163	# default implementation for ->signal
770		1164
771	our %SIG_CB;	1165	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1166
		1167	sub _signal_exec {
		1168	sysread $SIGPIPE_R, my $dummy, 4;
		1169
		1170	while (%SIG_EV) {
		1171	for (keys %SIG_EV) {
		1172	delete $SIG_EV{$_};
		1173	$_->() for values %{ $SIG_CB{$_} || {} };
		1174	}
		1175	}
		1176	}
772		1177
773	sub signal {	1178	sub signal {
774	my (undef, %arg) = @_;	1179	my (undef, %arg) = @_;
775		1180
		1181	unless ($SIGPIPE_R) {
		1182	require Fcntl;
		1183
		1184	if (AnyEvent::WIN32) {
		1185	require AnyEvent::Util;
		1186
		1187	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1188	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1189	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1190	} else {
		1191	pipe $SIGPIPE_R, $SIGPIPE_W;
		1192	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1193	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1194
		1195	# not strictly required, as $^F is normally 2, but let's make sure...
		1196	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1197	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1198	}
		1199
		1200	$SIGPIPE_R
		1201	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1202
		1203	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1204	}
		1205
776	my $signal = uc $arg{signal}	1206	my $signal = uc $arg{signal}
777	or Carp::croak "required option 'signal' is missing";	1207	or Carp::croak "required option 'signal' is missing";
778		1208
779	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1209	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
780	$SIG{$signal} ||= sub {	1210	$SIG{$signal} ||= sub {
781	$_->() for values %{ $SIG_CB{$signal} || {} };	1211	local $!;
		1212	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1213	undef $SIG_EV{$signal};
782	};	1214	};
783		1215
784	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1216	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
785	}	1217	}
786		1218
787	sub AnyEvent::Base::Signal::DESTROY {	1219	sub AnyEvent::Base::signal::DESTROY {
788	my ($signal, $cb) = @{$_[0]};	1220	my ($signal, $cb) = @{$_[0]};
789		1221
790	delete $SIG_CB{$signal}{$cb};	1222	delete $SIG_CB{$signal}{$cb};
791		1223
		1224	# delete doesn't work with older perls - they then
		1225	# print weird messages, or just unconditionally exit
		1226	# instead of getting the default action.
792	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1227	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
793	}	1228	}
794		1229
795	# default implementation for ->child	1230	# default implementation for ->child
796		1231
797	our %PID_CB;	1232	our %PID_CB;
798	our $CHLD_W;	1233	our $CHLD_W;
799	our $CHLD_DELAY_W;	1234	our $CHLD_DELAY_W;
800	our $PID_IDLE;
801	our $WNOHANG;	1235	our $WNOHANG;
802		1236
803	sub _child_wait {	1237	sub _sigchld {
804	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1238	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
805	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1239	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
806	(values %{ $PID_CB{0} || {} });	1240	(values %{ $PID_CB{0} || {} });
807	}	1241	}
808
809	undef $PID_IDLE;
810	}
811
812	sub _sigchld {
813	# make sure we deliver these changes "synchronous" with the event loop.
814	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
815	undef $CHLD_DELAY_W;
816	&_child_wait;
817	});
818	}	1242	}
819		1243
820	sub child {	1244	sub child {
821	my (undef, %arg) = @_;	1245	my (undef, %arg) = @_;
822		1246
823	defined (my $pid = $arg{pid} + 0)	1247	defined (my $pid = $arg{pid} + 0)
824	or Carp::croak "required option 'pid' is missing";	1248	or Carp::croak "required option 'pid' is missing";
825		1249
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1250	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1251
828	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1252	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
830	}
831		1253
832	unless ($CHLD_W) {	1254	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1255	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# child could be a zombie already, so make at least one round	1256	# child could be a zombie already, so make at least one round
835	&_sigchld;	1257	&_sigchld;
836	}	1258	}
837		1259
838	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1260	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
839	}	1261	}
840		1262
841	sub AnyEvent::Base::Child::DESTROY {	1263	sub AnyEvent::Base::child::DESTROY {
842	my ($pid, $cb) = @{$_[0]};	1264	my ($pid, $cb) = @{$_[0]};
843		1265
844	delete $PID_CB{$pid}{$cb};	1266	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1267	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1268
847	undef $CHLD_W unless keys %PID_CB;	1269	undef $CHLD_W unless keys %PID_CB;
848	}	1270	}
		1271
		1272	# idle emulation is done by simply using a timer, regardless
		1273	# of whether the process is idle or not, and not letting
		1274	# the callback use more than 50% of the time.
		1275	sub idle {
		1276	my (undef, %arg) = @_;
		1277
		1278	my ($cb, $w, $rcb) = $arg{cb};
		1279
		1280	$rcb = sub {
		1281	if ($cb) {
		1282	$w = _time;
		1283	&$cb;
		1284	$w = _time - $w;
		1285
		1286	# never use more then 50% of the time for the idle watcher,
		1287	# within some limits
		1288	$w = 0.0001 if $w < 0.0001;
		1289	$w = 5 if $w > 5;
		1290
		1291	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1292	} else {
		1293	# clean up...
		1294	undef $w;
		1295	undef $rcb;
		1296	}
		1297	};
		1298
		1299	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1300
		1301	bless \\$cb, "AnyEvent::Base::idle"
		1302	}
		1303
		1304	sub AnyEvent::Base::idle::DESTROY {
		1305	undef $${$_[0]};
		1306	}
		1307
		1308	package AnyEvent::CondVar;
		1309
		1310	our @ISA = AnyEvent::CondVar::Base::;
		1311
		1312	package AnyEvent::CondVar::Base;
		1313
		1314	use overload
		1315	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1316	fallback => 1;
		1317
		1318	sub _send {
		1319	# nop
		1320	}
		1321
		1322	sub send {
		1323	my $cv = shift;
		1324	$cv->{_ae_sent} = [@_];
		1325	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1326	$cv->_send;
		1327	}
		1328
		1329	sub croak {
		1330	$_[0]{_ae_croak} = $_[1];
		1331	$_[0]->send;
		1332	}
		1333
		1334	sub ready {
		1335	$_[0]{_ae_sent}
		1336	}
		1337
		1338	sub _wait {
		1339	AnyEvent->one_event while !$_[0]{_ae_sent};
		1340	}
		1341
		1342	sub recv {
		1343	$_[0]->_wait;
		1344
		1345	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1346	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1347	}
		1348
		1349	sub cb {
		1350	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1351	$_[0]{_ae_cb}
		1352	}
		1353
		1354	sub begin {
		1355	++$_[0]{_ae_counter};
		1356	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1357	}
		1358
		1359	sub end {
		1360	return if --$_[0]{_ae_counter};
		1361	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1362	}
		1363
		1364	# undocumented/compatibility with pre-3.4
		1365	*broadcast = \&send;
		1366	*wait = \&_wait;
		1367
		1368	=head1 ERROR AND EXCEPTION HANDLING
		1369
		1370	In general, AnyEvent does not do any error handling - it relies on the
		1371	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1372	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1373	checking of all AnyEvent methods, however, which is highly useful during
		1374	development.
		1375
		1376	As for exception handling (i.e. runtime errors and exceptions thrown while
		1377	executing a callback), this is not only highly event-loop specific, but
		1378	also not in any way wrapped by this module, as this is the job of the main
		1379	program.
		1380
		1381	The pure perl event loop simply re-throws the exception (usually
		1382	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1383	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1384	so on.
		1385
		1386	=head1 ENVIRONMENT VARIABLES
		1387
		1388	The following environment variables are used by this module or its
		1389	submodules.
		1390
		1391	Note that AnyEvent will remove I<all> environment variables starting with
		1392	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1393	enabled.
		1394
		1395	=over 4
		1396
		1397	=item C<PERL_ANYEVENT_VERBOSE>
		1398
		1399	By default, AnyEvent will be completely silent except in fatal
		1400	conditions. You can set this environment variable to make AnyEvent more
		1401	talkative.
		1402
		1403	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1404	conditions, such as not being able to load the event model specified by
		1405	C<PERL_ANYEVENT_MODEL>.
		1406
		1407	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1408	model it chooses.
		1409
		1410	=item C<PERL_ANYEVENT_STRICT>
		1411
		1412	AnyEvent does not do much argument checking by default, as thorough
		1413	argument checking is very costly. Setting this variable to a true value
		1414	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1415	check the arguments passed to most method calls. If it finds any problems,
		1416	it will croak.
		1417
		1418	In other words, enables "strict" mode.
		1419
		1420	Unlike C<use strict>, it is definitely recommended to keep it off in
		1421	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1422	developing programs can be very useful, however.
		1423
		1424	=item C<PERL_ANYEVENT_MODEL>
		1425
		1426	This can be used to specify the event model to be used by AnyEvent, before
		1427	auto detection and -probing kicks in. It must be a string consisting
		1428	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1429	and the resulting module name is loaded and if the load was successful,
		1430	used as event model. If it fails to load AnyEvent will proceed with
		1431	auto detection and -probing.
		1432
		1433	This functionality might change in future versions.
		1434
		1435	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1436	could start your program like this:
		1437
		1438	PERL_ANYEVENT_MODEL=Perl perl ...
		1439
		1440	=item C<PERL_ANYEVENT_PROTOCOLS>
		1441
		1442	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1443	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1444	of auto probing).
		1445
		1446	Must be set to a comma-separated list of protocols or address families,
		1447	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1448	used, and preference will be given to protocols mentioned earlier in the
		1449	list.
		1450
		1451	This variable can effectively be used for denial-of-service attacks
		1452	against local programs (e.g. when setuid), although the impact is likely
		1453	small, as the program has to handle conenction and other failures anyways.
		1454
		1455	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1456	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1457	- only support IPv4, never try to resolve or contact IPv6
		1458	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1459	IPv6, but prefer IPv6 over IPv4.
		1460
		1461	=item C<PERL_ANYEVENT_EDNS0>
		1462
		1463	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1464	for DNS. This extension is generally useful to reduce DNS traffic, but
		1465	some (broken) firewalls drop such DNS packets, which is why it is off by
		1466	default.
		1467
		1468	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1469	EDNS0 in its DNS requests.
		1470
		1471	=item C<PERL_ANYEVENT_MAX_FORKS>
		1472
		1473	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1474	will create in parallel.
		1475
		1476	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1477
		1478	The default value for the C<max_outstanding> parameter for the default DNS
		1479	resolver - this is the maximum number of parallel DNS requests that are
		1480	sent to the DNS server.
		1481
		1482	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1483
		1484	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1485	configuration) in the default resolver. When set to the empty string, no
		1486	default config will be used.
		1487
		1488	=back
849		1489
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1490	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1491
852	This is an advanced topic that you do not normally need to use AnyEvent in	1492	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	1493	a module. This section is only of use to event loop authors who want to
…		…
887		1527
888	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1528	I<rxvt-unicode> also cheats a bit by not providing blocking access to
889	condition variables: code blocking while waiting for a condition will	1529	condition variables: code blocking while waiting for a condition will
890	C<die>. This still works with most modules/usages, and blocking calls must	1530	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.	1531	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		1532
930	=head1 EXAMPLE PROGRAM	1533	=head1 EXAMPLE PROGRAM
931		1534
932	The following program uses an I/O watcher to read data from STDIN, a timer	1535	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	1536	to display a message once per second, and a condition variable to quit the
…		…
942	poll => 'r',	1545	poll => 'r',
943	cb => sub {	1546	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1547	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1548	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1549	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1550	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1551	},
949	);	1552	);
950		1553
951	my $time_watcher; # can only be used once	1554	my $time_watcher; # can only be used once
952		1555
…		…
957	});	1560	});
958	}	1561	}
959		1562
960	new_timer; # create first timer	1563	new_timer; # create first timer
961		1564
962	$cv->wait; # wait until user enters /^q/i	1565	$cv->recv; # wait until user enters /^q/i
963		1566
964	=head1 REAL-WORLD EXAMPLE	1567	=head1 REAL-WORLD EXAMPLE
965		1568
966	Consider the L<Net::FCP> module. It features (among others) the following	1569	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:	1570	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1620	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1621	or die "connection or write error";
1019	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1622	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020		1623
1021	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1624	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:	1625	result and signals any possible waiters that the request has finished:
1023		1626
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1627	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1628
1026	if (end-of-file or data complete) {	1629	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1630	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1631	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1632	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1633	}
1031		1634
1032	The C<result> method, finally, just waits for the finished signal (if the	1635	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	1636	request was already finished, it doesn't wait, of course, and returns the
1034	data:	1637	data:
1035		1638
1036	$txn->{finished}->wait;	1639	$txn->{finished}->recv;
1037	return $txn->{result};	1640	return $txn->{result};
1038		1641
1039	The actual code goes further and collects all errors (C<die>s, exceptions)	1642	The actual code goes further and collects all errors (C<die>s, exceptions)
1040	that occured during request processing. The C<result> method detects	1643	that occurred during request processing. The C<result> method detects
1041	whether an exception as thrown (it is stored inside the $txn object)	1644	whether an exception as thrown (it is stored inside the $txn object)
1042	and just throws the exception, which means connection errors and other	1645	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	1646	problems get reported tot he code that tries to use the result, not in a
1044	random callback.	1647	random callback.
1045		1648
…		…
1076		1679
1077	my $quit = AnyEvent->condvar;	1680	my $quit = AnyEvent->condvar;
1078		1681
1079	$fcp->txn_client_get ($url)->cb (sub {	1682	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1683	...
1081	$quit->broadcast;	1684	$quit->send;
1082	});	1685	});
1083		1686
1084	$quit->wait;	1687	$quit->recv;
1085		1688
1086		1689
1087	=head1 BENCHMARKS	1690	=head1 BENCHMARKS
1088		1691
1089	To give you an idea of the performance and overheads that AnyEvent adds	1692	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1091	of various event loops I prepared some benchmarks.	1694	of various event loops I prepared some benchmarks.
1092		1695
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1696	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1697
1095	Here is a benchmark of various supported event models used natively and	1698	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	1699	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,	1700	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.	1701	which it is), lets them fire exactly once and destroys them again.
1099		1702
1100	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1703	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101	distribution.	1704	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1721	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1722	and memory usage is not included in the figures.
1120		1723
1121	I<invoke> is the time, in microseconds, used to invoke a simple	1724	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	1725	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	1726	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1727	signal the end of this phase.
1125		1728
1126	I<destroy> is the time, in microseconds, that it takes to destroy a single	1729	I<destroy> is the time, in microseconds, that it takes to destroy a single
1127	watcher.	1730	watcher.
1128		1731
1129	=head3 Results	1732	=head3 Results
1130		1733
1131	name watchers bytes create invoke destroy comment	1734	name watchers bytes create invoke destroy comment
1132	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1735	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1133	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1736	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1134	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1737	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1135	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1738	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1136	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1739	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1137	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1740	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1741	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1742	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1138	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1743	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1139	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1744	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1140	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1745	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1141	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1746	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1142		1747
1143	=head3 Discussion	1748	=head3 Discussion
1144		1749
1145	The benchmark does I<not> measure scalability of the event loop very	1750	The benchmark does I<not> measure scalability of the event loop very
1146	well. For example, a select-based event loop (such as the pure perl one)	1751	well. For example, a select-based event loop (such as the pure perl one)
…		…
1171	performance becomes really bad with lots of file descriptors (and few of	1776	performance becomes really bad with lots of file descriptors (and few of
1172	them active), of course, but this was not subject of this benchmark.	1777	them active), of course, but this was not subject of this benchmark.
1173		1778
1174	The C<Event> module has a relatively high setup and callback invocation	1779	The C<Event> module has a relatively high setup and callback invocation
1175	cost, but overall scores in on the third place.	1780	cost, but overall scores in on the third place.
		1781
		1782	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1783	when using its pure perl backend.
1176		1784
1177	C<Glib>'s memory usage is quite a bit higher, but it features a	1785	C<Glib>'s memory usage is quite a bit higher, but it features a
1178	faster callback invocation and overall ends up in the same class as	1786	faster callback invocation and overall ends up in the same class as
1179	C<Event>. However, Glib scales extremely badly, doubling the number of	1787	C<Event>. However, Glib scales extremely badly, doubling the number of
1180	watchers increases the processing time by more than a factor of four,	1788	watchers increases the processing time by more than a factor of four,
…		…
1224		1832
1225	=back	1833	=back
1226		1834
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1835	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1836
1229	This benchmark atcually benchmarks the event loop itself. It works by	1837	This benchmark actually benchmarks the event loop itself. It works by
1230	creating a number of "servers": each server consists of a socketpair, a	1838	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	1839	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	1840	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".	1841	watcher reads a byte it will write that byte to a random other "server".
1234		1842
1235	The effect is that there will be a lot of I/O watchers, only part of which	1843	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	1844	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	1845	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	1846	timeout is reset each time something is read because that reflects how
1239	most timeouts work (and puts extra pressure on the event loops).	1847	most timeouts work (and puts extra pressure on the event loops).
1240		1848
1241	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1849	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	1850	(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.	1851	connections, most of which are idle at any one point in time.
1244		1852
1245	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1853	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246	distribution.	1854	distribution.
…		…
1248	=head3 Explanation of the columns	1856	=head3 Explanation of the columns
1249		1857
1250	I<sockets> is the number of sockets, and twice the number of "servers" (as	1858	I<sockets> is the number of sockets, and twice the number of "servers" (as
1251	each server has a read and write socket end).	1859	each server has a read and write socket end).
1252		1860
1253	I<create> is the time it takes to create a socketpair (which is	1861	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.	1862	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255		1863
1256	I<request>, the most important value, is the time it takes to handle a	1864	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	1865	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	1866	it to another server. This includes deleting the old timeout and creating
1259	a new one that moves the timeout into the future.	1867	a new one that moves the timeout into the future.
1260		1868
1261	=head3 Results	1869	=head3 Results
1262		1870
1263	name sockets create request	1871	name sockets create request
1264	EV 20000 69.01 11.16	1872	EV 20000 69.01 11.16
1265	Perl 20000 73.32 35.87	1873	Perl 20000 73.32 35.87
		1874	IOAsync 20000 157.00 98.14 epoll
		1875	IOAsync 20000 159.31 616.06 poll
1266	Event 20000 212.62 257.32	1876	Event 20000 212.62 257.32
1267	Glib 20000 651.16 1896.30	1877	Glib 20000 651.16 1896.30
1268	POE 20000 349.67 12317.24 uses POE::Loop::Event	1878	POE 20000 349.67 12317.24 uses POE::Loop::Event
1269		1879
1270	=head3 Discussion	1880	=head3 Discussion
1271		1881
1272	This benchmark I<does> measure scalability and overall performance of the	1882	This benchmark I<does> measure scalability and overall performance of the
1273	particular event loop.	1883	particular event loop.
…		…
1275	EV is again fastest. Since it is using epoll on my system, the setup time	1885	EV is again fastest. Since it is using epoll on my system, the setup time
1276	is relatively high, though.	1886	is relatively high, though.
1277		1887
1278	Perl surprisingly comes second. It is much faster than the C-based event	1888	Perl surprisingly comes second. It is much faster than the C-based event
1279	loops Event and Glib.	1889	loops Event and Glib.
		1890
		1891	IO::Async performs very well when using its epoll backend, and still quite
		1892	good compared to Glib when using its pure perl backend.
1280		1893
1281	Event suffers from high setup time as well (look at its code and you will	1894	Event suffers from high setup time as well (look at its code and you will
1282	understand why). Callback invocation also has a high overhead compared to	1895	understand why). Callback invocation also has a high overhead compared to
1283	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1896	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1284	uses select or poll in basically all documented configurations.	1897	uses select or poll in basically all documented configurations.
…		…
1331	speed most when you have lots of watchers, not when you only have a few of	1944	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1945	them).
1333		1946
1334	EV is again fastest.	1947	EV is again fastest.
1335		1948
1336	Perl again comes second. It is noticably faster than the C-based event	1949	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	1950	loops Event and Glib, although the difference is too small to really
1338	matter.	1951	matter.
1339		1952
1340	POE also performs much better in this case, but is is still far behind the	1953	POE also performs much better in this case, but is is still far behind the
1341	others.	1954	others.
…		…
1347	=item * C-based event loops perform very well with small number of	1960	=item * C-based event loops perform very well with small number of
1348	watchers, as the management overhead dominates.	1961	watchers, as the management overhead dominates.
1349		1962
1350	=back	1963	=back
1351		1964
		1965	=head2 THE IO::Lambda BENCHMARK
		1966
		1967	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1968	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1969	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1970	shouldn't come as a surprise to anybody). As such, the benchmark is
		1971	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1972	very optimal. But how would AnyEvent compare when used without the extra
		1973	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1974
		1975	The benchmark itself creates an echo-server, and then, for 500 times,
		1976	connects to the echo server, sends a line, waits for the reply, and then
		1977	creates the next connection. This is a rather bad benchmark, as it doesn't
		1978	test the efficiency of the framework or much non-blocking I/O, but it is a
		1979	benchmark nevertheless.
		1980
		1981	name runtime
		1982	Lambda/select 0.330 sec
		1983	+ optimized 0.122 sec
		1984	Lambda/AnyEvent 0.327 sec
		1985	+ optimized 0.138 sec
		1986	Raw sockets/select 0.077 sec
		1987	POE/select, components 0.662 sec
		1988	POE/select, raw sockets 0.226 sec
		1989	POE/select, optimized 0.404 sec
		1990
		1991	AnyEvent/select/nb 0.085 sec
		1992	AnyEvent/EV/nb 0.068 sec
		1993	+state machine 0.134 sec
		1994
		1995	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1996	benchmarks actually make blocking connects and use 100% blocking I/O,
		1997	defeating the purpose of an event-based solution. All of the newly
		1998	written AnyEvent benchmarks use 100% non-blocking connects (using
		1999	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2000	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2001	generally require a lot more bookkeeping and event handling than blocking
		2002	connects (which involve a single syscall only).
		2003
		2004	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2005	offers similar expressive power as POE and IO::Lambda, using conventional
		2006	Perl syntax. This means that both the echo server and the client are 100%
		2007	non-blocking, further placing it at a disadvantage.
		2008
		2009	As you can see, the AnyEvent + EV combination even beats the
		2010	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2011	backend easily beats IO::Lambda and POE.
		2012
		2013	And even the 100% non-blocking version written using the high-level (and
		2014	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2015	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2016	in a non-blocking way.
		2017
		2018	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2019	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2020	part of the IO::lambda distribution and were used without any changes.
		2021
		2022
		2023	=head1 SIGNALS
		2024
		2025	AnyEvent currently installs handlers for these signals:
		2026
		2027	=over 4
		2028
		2029	=item SIGCHLD
		2030
		2031	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2032	emulation for event loops that do not support them natively. Also, some
		2033	event loops install a similar handler.
		2034
		2035	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2036	reset it to default, to avoid losing child exit statuses.
		2037
		2038	=item SIGPIPE
		2039
		2040	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2041	when AnyEvent gets loaded.
		2042
		2043	The rationale for this is that AnyEvent users usually do not really depend
		2044	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2045	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2046	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2047	some random socket.
		2048
		2049	The rationale for installing a no-op handler as opposed to ignoring it is
		2050	that this way, the handler will be restored to defaults on exec.
		2051
		2052	Feel free to install your own handler, or reset it to defaults.
		2053
		2054	=back
		2055
		2056	=cut
		2057
		2058	undef $SIG{CHLD}
		2059	if $SIG{CHLD} eq 'IGNORE';
		2060
		2061	$SIG{PIPE} = sub { }
		2062	unless defined $SIG{PIPE};
1352		2063
1353	=head1 FORK	2064	=head1 FORK
1354		2065
1355	Most event libraries are not fork-safe. The ones who are usually are	2066	Most event libraries are not fork-safe. The ones who are usually are
1356	because they rely on inefficient but fork-safe C<select> or C<poll>	2067	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1370	specified in the variable.	2081	specified in the variable.
1371		2082
1372	You can make AnyEvent completely ignore this variable by deleting it	2083	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:	2084	before the first watcher gets created, e.g. with a C<BEGIN> block:
1374		2085
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2086	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		2087
1377	use AnyEvent;	2088	use AnyEvent;
		2089
		2090	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2091	be used to probe what backend is used and gain other information (which is
		2092	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2093	$ENV{PERL_ANYEVENT_STRICT}.
		2094
		2095	Note that AnyEvent will remove I<all> environment variables starting with
		2096	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2097	enabled.
		2098
		2099
		2100	=head1 BUGS
		2101
		2102	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2103	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2104	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2105	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2106	pronounced).
1378		2107
1379		2108
1380	=head1 SEE ALSO	2109	=head1 SEE ALSO
1381		2110
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2111	Utility functions: L<AnyEvent::Util>.
1383	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2112
		2113	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	2114	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		2115
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2116	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2117	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>,	2118	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2119	L<AnyEvent::Impl::POE>.
1390		2120
		2121	Non-blocking file handles, sockets, TCP clients and
		2122	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		2123
		2124	Asynchronous DNS: L<AnyEvent::DNS>.
		2125
		2126	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		2127
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2128	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		2129
1393		2130
1394	=head1 AUTHOR	2131	=head1 AUTHOR
1395		2132
1396	Marc Lehmann <schmorp@schmorp.de>	2133	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	2134	http://home.schmorp.de/
1398		2135
1399	=cut	2136	=cut
1400		2137
1401	1	2138	1
1402		2139

Diff Legend

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