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Revision 1.198 by root, Thu Mar 26 20:17:44 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, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
		12
		13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
12	...	23	...
13	});	24	});
14		25
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...
17	});
18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		27	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	28	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	48	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	49	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	63	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	64	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70
71		92
72	=head1 DESCRIPTION	93	=head1 DESCRIPTION
73		94
74	L<AnyEvent> provides an identical interface to multiple event loops. This	95	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	96	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	101	module.
81		102
82	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<Tk>, L<AnyEvent::Impl::Perl>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
90	found, AnyEvent will fall back to a pure-perl event loop, which is not	111	found, AnyEvent will fall back to a pure-perl event loop, which is not
91	very efficient, but should work everywhere.	112	very efficient, but should work everywhere.
92		113
…		…
103	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
104	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
105		126
106	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
109		130
110	=head1 WATCHERS	131	=head1 WATCHERS
111		132
112	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
115		136
116	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
119	is in control).	140	is in control).
120		141
		142	Note that B<callbacks must not permanently change global variables>
		143	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		144	callbacks must not C<die> >>. The former is good programming practise in
		145	Perl and the latter stems from the fact that exception handling differs
		146	widely between event loops.
		147
121	To disable the watcher you have to destroy it (e.g. by setting the	148	To disable the watcher you have to destroy it (e.g. by setting the
122	variable you store it in to C<undef> or otherwise deleting all references	149	variable you store it in to C<undef> or otherwise deleting all references
123	to it).	150	to it).
124		151
125	All watchers are created by calling a method on the C<AnyEvent> class.	152	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
127	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
128	example), or need to refer to their watcher object in other ways.	155	example), or need to refer to their watcher object in other ways.
129		156
130	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
131		158
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
134	undef $w;	161	undef $w;
135	});	162	});
136		163
137	Note that C<my $w; $w => combination. This is necessary because in Perl,	164	Note that C<my $w; $w => combination. This is necessary because in Perl,
138	my variables are only visible after the statement in which they are	165	my variables are only visible after the statement in which they are
139	declared.	166	declared.
140		167
141	=head2 IO WATCHERS	168	=head2 I/O WATCHERS
142		169
143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
145		172
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for	173	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
		174	(AnyEvent might or might not keep a reference to this file handle). C<poll>
147	events. C<poll> must be a string that is either C<r> or C<w>, which	175	must be a string that is either C<r> or C<w>, which creates a watcher
148	creates a watcher waiting for "r"eadable or "w"ritable events,	176	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149	respectively. C<cb> is the callback to invoke each time the file handle	177	callback to invoke each time the file handle becomes ready.
150	becomes ready.
151		178
152	As long as the I/O watcher exists it will keep the file descriptor or a	179	Although the callback might get passed parameters, their value and
153	copy of it alive/open.	180	presence is undefined and you cannot rely on them. Portable AnyEvent
		181	callbacks cannot use arguments passed to I/O watcher callbacks.
154		182
		183	The I/O watcher might use the underlying file descriptor or a copy of it.
155	It is not allowed to close a file handle as long as any watcher is active	184	You must not close a file handle as long as any watcher is active on the
156	on the underlying file descriptor.	185	underlying file descriptor.
157		186
158	Some event loops issue spurious readyness notifications, so you should	187	Some event loops issue spurious readyness notifications, so you should
159	always use non-blocking calls when reading/writing from/to your file	188	always use non-blocking calls when reading/writing from/to your file
160	handles.	189	handles.
161		190
162	Example:
163
164	# wait for readability of STDIN, then read a line and disable the watcher	191	Example: wait for readability of STDIN, then read a line and disable the
		192	watcher.
		193
165	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	194	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
166	chomp (my $input = <STDIN>);	195	chomp (my $input = <STDIN>);
167	warn "read: $input\n";	196	warn "read: $input\n";
168	undef $w;	197	undef $w;
169	});	198	});
…		…
172		201
173	You can create a time watcher by calling the C<< AnyEvent->timer >>	202	You can create a time watcher by calling the C<< AnyEvent->timer >>
174	method with the following mandatory arguments:	203	method with the following mandatory arguments:
175		204
176	C<after> specifies after how many seconds (fractional values are	205	C<after> specifies after how many seconds (fractional values are
177	supported) should the timer activate. C<cb> the callback to invoke in that	206	supported) the callback should be invoked. C<cb> is the callback to invoke
178	case.	207	in that case.
179		208
180	The timer callback will be invoked at most once: if you want a repeating	209	Although the callback might get passed parameters, their value and
181	timer you have to create a new watcher (this is a limitation by both Tk	210	presence is undefined and you cannot rely on them. Portable AnyEvent
182	and Glib).	211	callbacks cannot use arguments passed to time watcher callbacks.
183		212
184	Example:	213	The callback will normally be invoked once only. If you specify another
		214	parameter, C<interval>, as a strictly positive number (> 0), then the
		215	callback will be invoked regularly at that interval (in fractional
		216	seconds) after the first invocation. If C<interval> is specified with a
		217	false value, then it is treated as if it were missing.
185		218
		219	The callback will be rescheduled before invoking the callback, but no
		220	attempt is done to avoid timer drift in most backends, so the interval is
		221	only approximate.
		222
186	# fire an event after 7.7 seconds	223	Example: fire an event after 7.7 seconds.
		224
187	my $w = AnyEvent->timer (after => 7.7, cb => sub {	225	my $w = AnyEvent->timer (after => 7.7, cb => sub {
188	warn "timeout\n";	226	warn "timeout\n";
189	});	227	});
190		228
191	# to cancel the timer:	229	# to cancel the timer:
192	undef $w;	230	undef $w;
193		231
194	Example 2:
195
196	# fire an event after 0.5 seconds, then roughly every second	232	Example 2: fire an event after 0.5 seconds, then roughly every second.
197	my $w;
198		233
199	my $cb = sub {
200	# cancel the old timer while creating a new one
201	$w = AnyEvent->timer (after => 1, cb => $cb);	234	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		235	warn "timeout\n";
202	};	236	};
203
204	# start the "loop" by creating the first watcher
205	$w = AnyEvent->timer (after => 0.5, cb => $cb);
206		237
207	=head3 TIMING ISSUES	238	=head3 TIMING ISSUES
208		239
209	There are two ways to handle timers: based on real time (relative, "fire	240	There are two ways to handle timers: based on real time (relative, "fire
210	in 10 seconds") and based on wallclock time (absolute, "fire at 12	241	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
222	timers.	253	timers.
223		254
224	AnyEvent always prefers relative timers, if available, matching the	255	AnyEvent always prefers relative timers, if available, matching the
225	AnyEvent API.	256	AnyEvent API.
226		257
		258	AnyEvent has two additional methods that return the "current time":
		259
		260	=over 4
		261
		262	=item AnyEvent->time
		263
		264	This returns the "current wallclock time" as a fractional number of
		265	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		266	return, and the result is guaranteed to be compatible with those).
		267
		268	It progresses independently of any event loop processing, i.e. each call
		269	will check the system clock, which usually gets updated frequently.
		270
		271	=item AnyEvent->now
		272
		273	This also returns the "current wallclock time", but unlike C<time>, above,
		274	this value might change only once per event loop iteration, depending on
		275	the event loop (most return the same time as C<time>, above). This is the
		276	time that AnyEvent's timers get scheduled against.
		277
		278	I<In almost all cases (in all cases if you don't care), this is the
		279	function to call when you want to know the current time.>
		280
		281	This function is also often faster then C<< AnyEvent->time >>, and
		282	thus the preferred method if you want some timestamp (for example,
		283	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		284
		285	The rest of this section is only of relevance if you try to be very exact
		286	with your timing, you can skip it without bad conscience.
		287
		288	For a practical example of when these times differ, consider L<Event::Lib>
		289	and L<EV> and the following set-up:
		290
		291	The event loop is running and has just invoked one of your callback at
		292	time=500 (assume no other callbacks delay processing). In your callback,
		293	you wait a second by executing C<sleep 1> (blocking the process for a
		294	second) and then (at time=501) you create a relative timer that fires
		295	after three seconds.
		296
		297	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		298	both return C<501>, because that is the current time, and the timer will
		299	be scheduled to fire at time=504 (C<501> + C<3>).
		300
		301	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		302	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		303	last event processing phase started. With L<EV>, your timer gets scheduled
		304	to run at time=503 (C<500> + C<3>).
		305
		306	In one sense, L<Event::Lib> is more exact, as it uses the current time
		307	regardless of any delays introduced by event processing. However, most
		308	callbacks do not expect large delays in processing, so this causes a
		309	higher drift (and a lot more system calls to get the current time).
		310
		311	In another sense, L<EV> is more exact, as your timer will be scheduled at
		312	the same time, regardless of how long event processing actually took.
		313
		314	In either case, if you care (and in most cases, you don't), then you
		315	can get whatever behaviour you want with any event loop, by taking the
		316	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		317	account.
		318
		319	=back
		320
227	=head2 SIGNAL WATCHERS	321	=head2 SIGNAL WATCHERS
228		322
229	You can watch for signals using a signal watcher, C<signal> is the signal	323	You can watch for signals using a signal watcher, C<signal> is the signal
230	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	324	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
231	be invoked whenever a signal occurs.	325	callback to be invoked whenever a signal occurs.
232		326
		327	Although the callback might get passed parameters, their value and
		328	presence is undefined and you cannot rely on them. Portable AnyEvent
		329	callbacks cannot use arguments passed to signal watcher callbacks.
		330
233	Multiple signal occurances can be clumped together into one callback	331	Multiple signal occurrences can be clumped together into one callback
234	invocation, and callback invocation will be synchronous. synchronous means	332	invocation, and callback invocation will be synchronous. Synchronous means
235	that it might take a while until the signal gets handled by the process,	333	that it might take a while until the signal gets handled by the process,
236	but it is guarenteed not to interrupt any other callbacks.	334	but it is guaranteed not to interrupt any other callbacks.
237		335
238	The main advantage of using these watchers is that you can share a signal	336	The main advantage of using these watchers is that you can share a signal
239	between multiple watchers.	337	between multiple watchers.
240		338
241	This watcher might use C<%SIG>, so programs overwriting those signals	339	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
248	=head2 CHILD PROCESS WATCHERS	346	=head2 CHILD PROCESS WATCHERS
249		347
250	You can also watch on a child process exit and catch its exit status.	348	You can also watch on a child process exit and catch its exit status.
251		349
252	The child process is specified by the C<pid> argument (if set to C<0>, it	350	The child process is specified by the C<pid> argument (if set to C<0>, it
253	watches for any child process exit). The watcher will trigger as often	351	watches for any child process exit). The watcher will triggered only when
254	as status change for the child are received. This works by installing a	352	the child process has finished and an exit status is available, not on
255	signal handler for C<SIGCHLD>. The callback will be called with the pid	353	any trace events (stopped/continued).
256	and exit status (as returned by waitpid).
257		354
258	Example: wait for pid 1333	355	The callback will be called with the pid and exit status (as returned by
		356	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		357	callback arguments.
259		358
		359	This watcher type works by installing a signal handler for C<SIGCHLD>,
		360	and since it cannot be shared, nothing else should use SIGCHLD or reap
		361	random child processes (waiting for specific child processes, e.g. inside
		362	C<system>, is just fine).
		363
		364	There is a slight catch to child watchers, however: you usually start them
		365	I<after> the child process was created, and this means the process could
		366	have exited already (and no SIGCHLD will be sent anymore).
		367
		368	Not all event models handle this correctly (POE doesn't), but even for
		369	event models that I<do> handle this correctly, they usually need to be
		370	loaded before the process exits (i.e. before you fork in the first place).
		371
		372	This means you cannot create a child watcher as the very first thing in an
		373	AnyEvent program, you I<have> to create at least one watcher before you
		374	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
		375
		376	Example: fork a process and wait for it
		377
		378	my $done = AnyEvent->condvar;
		379
		380	my $pid = fork or exit 5;
		381
260	my $w = AnyEvent->child (	382	my $w = AnyEvent->child (
261	pid => 1333,	383	pid => $pid,
262	cb => sub {	384	cb => sub {
263	my ($pid, $status) = @_;	385	my ($pid, $status) = @_;
264	warn "pid $pid exited with status $status";	386	warn "pid $pid exited with status $status";
		387	$done->send;
265	},	388	},
266	);	389	);
		390
		391	# do something else, then wait for process exit
		392	$done->recv;
267		393
268	=head2 CONDITION VARIABLES	394	=head2 CONDITION VARIABLES
269		395
		396	If you are familiar with some event loops you will know that all of them
		397	require you to run some blocking "loop", "run" or similar function that
		398	will actively watch for new events and call your callbacks.
		399
		400	AnyEvent is different, it expects somebody else to run the event loop and
		401	will only block when necessary (usually when told by the user).
		402
		403	The instrument to do that is called a "condition variable", so called
		404	because they represent a condition that must become true.
		405
270	Condition variables can be created by calling the C<< AnyEvent->condvar >>	406	Condition variables can be created by calling the C<< AnyEvent->condvar
271	method without any arguments.	407	>> method, usually without arguments. The only argument pair allowed is
272		408
273	A condition variable waits for a condition - precisely that the C<<	409	C<cb>, which specifies a callback to be called when the condition variable
274	->broadcast >> method has been called.	410	becomes true, with the condition variable as the first argument (but not
		411	the results).
275		412
276	They are very useful to signal that a condition has been fulfilled, for	413	After creation, the condition variable is "false" until it becomes "true"
		414	by calling the C<send> method (or calling the condition variable as if it
		415	were a callback, read about the caveats in the description for the C<<
		416	->send >> method).
		417
		418	Condition variables are similar to callbacks, except that you can
		419	optionally wait for them. They can also be called merge points - points
		420	in time where multiple outstanding events have been processed. And yet
		421	another way to call them is transactions - each condition variable can be
		422	used to represent a transaction, which finishes at some point and delivers
		423	a result.
		424
		425	Condition variables are very useful to signal that something has finished,
277	example, if you write a module that does asynchronous http requests,	426	for example, if you write a module that does asynchronous http requests,
278	then a condition variable would be the ideal candidate to signal the	427	then a condition variable would be the ideal candidate to signal the
279	availability of results.	428	availability of results. The user can either act when the callback is
		429	called or can synchronously C<< ->recv >> for the results.
280		430
281	You can also use condition variables to block your main program until	431	You can also use them to simulate traditional event loops - for example,
282	an event occurs - for example, you could C<< ->wait >> in your main	432	you can block your main program until an event occurs - for example, you
283	program until the user clicks the Quit button in your app, which would C<<	433	could C<< ->recv >> in your main program until the user clicks the Quit
284	->broadcast >> the "quit" event.	434	button of your app, which would C<< ->send >> the "quit" event.
285		435
286	Note that condition variables recurse into the event loop - if you have	436	Note that condition variables recurse into the event loop - if you have
287	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	437	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
288	lose. Therefore, condition variables are good to export to your caller, but	438	lose. Therefore, condition variables are good to export to your caller, but
289	you should avoid making a blocking wait yourself, at least in callbacks,	439	you should avoid making a blocking wait yourself, at least in callbacks,
290	as this asks for trouble.	440	as this asks for trouble.
291		441
292	This object has two methods:	442	Condition variables are represented by hash refs in perl, and the keys
		443	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		444	easy (it is often useful to build your own transaction class on top of
		445	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		446	it's C<new> method in your own C<new> method.
		447
		448	There are two "sides" to a condition variable - the "producer side" which
		449	eventually calls C<< -> send >>, and the "consumer side", which waits
		450	for the send to occur.
		451
		452	Example: wait for a timer.
		453
		454	# wait till the result is ready
		455	my $result_ready = AnyEvent->condvar;
		456
		457	# do something such as adding a timer
		458	# or socket watcher the calls $result_ready->send
		459	# when the "result" is ready.
		460	# in this case, we simply use a timer:
		461	my $w = AnyEvent->timer (
		462	after => 1,
		463	cb => sub { $result_ready->send },
		464	);
		465
		466	# this "blocks" (while handling events) till the callback
		467	# calls send
		468	$result_ready->recv;
		469
		470	Example: wait for a timer, but take advantage of the fact that
		471	condition variables are also code references.
		472
		473	my $done = AnyEvent->condvar;
		474	my $delay = AnyEvent->timer (after => 5, cb => $done);
		475	$done->recv;
		476
		477	Example: Imagine an API that returns a condvar and doesn't support
		478	callbacks. This is how you make a synchronous call, for example from
		479	the main program:
		480
		481	use AnyEvent::CouchDB;
		482
		483	...
		484
		485	my @info = $couchdb->info->recv;
		486
		487	And this is how you would just ste a callback to be called whenever the
		488	results are available:
		489
		490	$couchdb->info->cb (sub {
		491	my @info = $_[0]->recv;
		492	});
		493
		494	=head3 METHODS FOR PRODUCERS
		495
		496	These methods should only be used by the producing side, i.e. the
		497	code/module that eventually sends the signal. Note that it is also
		498	the producer side which creates the condvar in most cases, but it isn't
		499	uncommon for the consumer to create it as well.
293		500
294	=over 4	501	=over 4
295		502
		503	=item $cv->send (...)
		504
		505	Flag the condition as ready - a running C<< ->recv >> and all further
		506	calls to C<recv> will (eventually) return after this method has been
		507	called. If nobody is waiting the send will be remembered.
		508
		509	If a callback has been set on the condition variable, it is called
		510	immediately from within send.
		511
		512	Any arguments passed to the C<send> call will be returned by all
		513	future C<< ->recv >> calls.
		514
		515	Condition variables are overloaded so one can call them directly
		516	(as a code reference). Calling them directly is the same as calling
		517	C<send>. Note, however, that many C-based event loops do not handle
		518	overloading, so as tempting as it may be, passing a condition variable
		519	instead of a callback does not work. Both the pure perl and EV loops
		520	support overloading, however, as well as all functions that use perl to
		521	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		522	example).
		523
		524	=item $cv->croak ($error)
		525
		526	Similar to send, but causes all call's to C<< ->recv >> to invoke
		527	C<Carp::croak> with the given error message/object/scalar.
		528
		529	This can be used to signal any errors to the condition variable
		530	user/consumer.
		531
		532	=item $cv->begin ([group callback])
		533
296	=item $cv->wait	534	=item $cv->end
297		535
298	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		537
		538	These two methods can be used to combine many transactions/events into
		539	one. For example, a function that pings many hosts in parallel might want
		540	to use a condition variable for the whole process.
		541
		542	Every call to C<< ->begin >> will increment a counter, and every call to
		543	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		544	>>, the (last) callback passed to C<begin> will be executed. That callback
		545	is I<supposed> to call C<< ->send >>, but that is not required. If no
		546	callback was set, C<send> will be called without any arguments.
		547
		548	Let's clarify this with the ping example:
		549
		550	my $cv = AnyEvent->condvar;
		551
		552	my %result;
		553	$cv->begin (sub { $cv->send (\%result) });
		554
		555	for my $host (@list_of_hosts) {
		556	$cv->begin;
		557	ping_host_then_call_callback $host, sub {
		558	$result{$host} = ...;
		559	$cv->end;
		560	};
		561	}
		562
		563	$cv->end;
		564
		565	This code fragment supposedly pings a number of hosts and calls
		566	C<send> after results for all then have have been gathered - in any
		567	order. To achieve this, the code issues a call to C<begin> when it starts
		568	each ping request and calls C<end> when it has received some result for
		569	it. Since C<begin> and C<end> only maintain a counter, the order in which
		570	results arrive is not relevant.
		571
		572	There is an additional bracketing call to C<begin> and C<end> outside the
		573	loop, which serves two important purposes: first, it sets the callback
		574	to be called once the counter reaches C<0>, and second, it ensures that
		575	C<send> is called even when C<no> hosts are being pinged (the loop
		576	doesn't execute once).
		577
		578	This is the general pattern when you "fan out" into multiple subrequests:
		579	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		580	is called at least once, and then, for each subrequest you start, call
		581	C<begin> and for each subrequest you finish, call C<end>.
		582
		583	=back
		584
		585	=head3 METHODS FOR CONSUMERS
		586
		587	These methods should only be used by the consuming side, i.e. the
		588	code awaits the condition.
		589
		590	=over 4
		591
		592	=item $cv->recv
		593
		594	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
299	called on c<$cv>, while servicing other watchers normally.	595	>> methods have been called on c<$cv>, while servicing other watchers
		596	normally.
300		597
301	You can only wait once on a condition - additional calls will return	598	You can only wait once on a condition - additional calls are valid but
302	immediately.	599	will return immediately.
		600
		601	If an error condition has been set by calling C<< ->croak >>, then this
		602	function will call C<croak>.
		603
		604	In list context, all parameters passed to C<send> will be returned,
		605	in scalar context only the first one will be returned.
303		606
304	Not all event models support a blocking wait - some die in that case	607	Not all event models support a blocking wait - some die in that case
305	(programs might want to do that to stay interactive), so I<if you are	608	(programs might want to do that to stay interactive), so I<if you are
306	using this from a module, never require a blocking wait>, but let the	609	using this from a module, never require a blocking wait>, but let the
307	caller decide whether the call will block or not (for example, by coupling	610	caller decide whether the call will block or not (for example, by coupling
308	condition variables with some kind of request results and supporting	611	condition variables with some kind of request results and supporting
309	callbacks so the caller knows that getting the result will not block,	612	callbacks so the caller knows that getting the result will not block,
310	while still suppporting blocking waits if the caller so desires).	613	while still supporting blocking waits if the caller so desires).
311		614
312	Another reason I<never> to C<< ->wait >> in a module is that you cannot	615	Another reason I<never> to C<< ->recv >> in a module is that you cannot
313	sensibly have two C<< ->wait >>'s in parallel, as that would require	616	sensibly have two C<< ->recv >>'s in parallel, as that would require
314	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
315	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	618	can supply.
316	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
317	from different coroutines, however).
318		619
319	=item $cv->broadcast	620	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		621	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		622	versions and also integrates coroutines into AnyEvent, making blocking
		623	C<< ->recv >> calls perfectly safe as long as they are done from another
		624	coroutine (one that doesn't run the event loop).
320		625
321	Flag the condition as ready - a running C<< ->wait >> and all further	626	You can ensure that C<< -recv >> never blocks by setting a callback and
322	calls to C<wait> will (eventually) return after this method has been	627	only calling C<< ->recv >> from within that callback (or at a later
323	called. If nobody is waiting the broadcast will be remembered..	628	time). This will work even when the event loop does not support blocking
		629	waits otherwise.
		630
		631	=item $bool = $cv->ready
		632
		633	Returns true when the condition is "true", i.e. whether C<send> or
		634	C<croak> have been called.
		635
		636	=item $cb = $cv->cb ($cb->($cv))
		637
		638	This is a mutator function that returns the callback set and optionally
		639	replaces it before doing so.
		640
		641	The callback will be called when the condition becomes "true", i.e. when
		642	C<send> or C<croak> are called, with the only argument being the condition
		643	variable itself. Calling C<recv> inside the callback or at any later time
		644	is guaranteed not to block.
324		645
325	=back	646	=back
326
327	Example:
328
329	# wait till the result is ready
330	my $result_ready = AnyEvent->condvar;
331
332	# do something such as adding a timer
333	# or socket watcher the calls $result_ready->broadcast
334	# when the "result" is ready.
335	# in this case, we simply use a timer:
336	my $w = AnyEvent->timer (
337	after => 1,
338	cb => sub { $result_ready->broadcast },
339	);
340
341	# this "blocks" (while handling events) till the watcher
342	# calls broadcast
343	$result_ready->wait;
344		647
345	=head1 GLOBAL VARIABLES AND FUNCTIONS	648	=head1 GLOBAL VARIABLES AND FUNCTIONS
346		649
347	=over 4	650	=over 4
348		651
…		…
354	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
355	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
356		659
357	The known classes so far are:	660	The known classes so far are:
358		661
359	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
360	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
361	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
362	AnyEvent::Impl::Event based on Event, second best choice.	663	AnyEvent::Impl::Event based on Event, second best choice.
		664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
363	AnyEvent::Impl::Glib based on Glib, third-best choice.	665	AnyEvent::Impl::Glib based on Glib, third-best choice.
364	AnyEvent::Impl::Tk based on Tk, very bad choice.	666	AnyEvent::Impl::Tk based on Tk, very bad choice.
365	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
366	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	667	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
367	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	668	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
368	AnyEvent::Impl::POE based on POE, not generic enough for full support.	669	AnyEvent::Impl::POE based on POE, not generic enough for full support.
369		670
370	There is no support for WxWidgets, as WxWidgets has no support for	671	There is no support for WxWidgets, as WxWidgets has no support for
…		…
382	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
383	if necessary. You should only call this function right before you would	684	if necessary. You should only call this function right before you would
384	have created an AnyEvent watcher anyway, that is, as late as possible at	685	have created an AnyEvent watcher anyway, that is, as late as possible at
385	runtime.	686	runtime.
386		687
		688	=item $guard = AnyEvent::post_detect { BLOCK }
		689
		690	Arranges for the code block to be executed as soon as the event model is
		691	autodetected (or immediately if this has already happened).
		692
		693	If called in scalar or list context, then it creates and returns an object
		694	that automatically removes the callback again when it is destroyed. See
		695	L<Coro::BDB> for a case where this is useful.
		696
		697	=item @AnyEvent::post_detect
		698
		699	If there are any code references in this array (you can C<push> to it
		700	before or after loading AnyEvent), then they will called directly after
		701	the event loop has been chosen.
		702
		703	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		704	if it contains a true value then the event loop has already been detected,
		705	and the array will be ignored.
		706
		707	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		708
387	=back	709	=back
388		710
389	=head1 WHAT TO DO IN A MODULE	711	=head1 WHAT TO DO IN A MODULE
390		712
391	As a module author, you should C<use AnyEvent> and call AnyEvent methods	713	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
394	Be careful when you create watchers in the module body - AnyEvent will	716	Be careful when you create watchers in the module body - AnyEvent will
395	decide which event module to use as soon as the first method is called, so	717	decide which event module to use as soon as the first method is called, so
396	by calling AnyEvent in your module body you force the user of your module	718	by calling AnyEvent in your module body you force the user of your module
397	to load the event module first.	719	to load the event module first.
398		720
399	Never call C<< ->wait >> on a condition variable unless you I<know> that	721	Never call C<< ->recv >> on a condition variable unless you I<know> that
400	the C<< ->broadcast >> method has been called on it already. This is	722	the C<< ->send >> method has been called on it already. This is
401	because it will stall the whole program, and the whole point of using	723	because it will stall the whole program, and the whole point of using
402	events is to stay interactive.	724	events is to stay interactive.
403		725
404	It is fine, however, to call C<< ->wait >> when the user of your module	726	It is fine, however, to call C<< ->recv >> when the user of your module
405	requests it (i.e. if you create a http request object ad have a method	727	requests it (i.e. if you create a http request object ad have a method
406	called C<results> that returns the results, it should call C<< ->wait >>	728	called C<results> that returns the results, it should call C<< ->recv >>
407	freely, as the user of your module knows what she is doing. always).	729	freely, as the user of your module knows what she is doing. always).
408		730
409	=head1 WHAT TO DO IN THE MAIN PROGRAM	731	=head1 WHAT TO DO IN THE MAIN PROGRAM
410		732
411	There will always be a single main program - the only place that should	733	There will always be a single main program - the only place that should
…		…
413		735
414	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	736	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
415	do anything special (it does not need to be event-based) and let AnyEvent	737	do anything special (it does not need to be event-based) and let AnyEvent
416	decide which implementation to chose if some module relies on it.	738	decide which implementation to chose if some module relies on it.
417		739
418	If the main program relies on a specific event model. For example, in	740	If the main program relies on a specific event model - for example, in
419	Gtk2 programs you have to rely on the Glib module. You should load the	741	Gtk2 programs you have to rely on the Glib module - you should load the
420	event module before loading AnyEvent or any module that uses it: generally	742	event module before loading AnyEvent or any module that uses it: generally
421	speaking, you should load it as early as possible. The reason is that	743	speaking, you should load it as early as possible. The reason is that
422	modules might create watchers when they are loaded, and AnyEvent will	744	modules might create watchers when they are loaded, and AnyEvent will
423	decide on the event model to use as soon as it creates watchers, and it	745	decide on the event model to use as soon as it creates watchers, and it
424	might chose the wrong one unless you load the correct one yourself.	746	might chose the wrong one unless you load the correct one yourself.
425		747
426	You can chose to use a rather inefficient pure-perl implementation by	748	You can chose to use a pure-perl implementation by loading the
427	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	749	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
428	behaviour everywhere, but letting AnyEvent chose is generally better.	750	everywhere, but letting AnyEvent chose the model is generally better.
		751
		752	=head2 MAINLOOP EMULATION
		753
		754	Sometimes (often for short test scripts, or even standalone programs who
		755	only want to use AnyEvent), you do not want to run a specific event loop.
		756
		757	In that case, you can use a condition variable like this:
		758
		759	AnyEvent->condvar->recv;
		760
		761	This has the effect of entering the event loop and looping forever.
		762
		763	Note that usually your program has some exit condition, in which case
		764	it is better to use the "traditional" approach of storing a condition
		765	variable somewhere, waiting for it, and sending it when the program should
		766	exit cleanly.
		767
		768
		769	=head1 OTHER MODULES
		770
		771	The following is a non-exhaustive list of additional modules that use
		772	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		773	in the same program. Some of the modules come with AnyEvent, some are
		774	available via CPAN.
		775
		776	=over 4
		777
		778	=item L<AnyEvent::Util>
		779
		780	Contains various utility functions that replace often-used but blocking
		781	functions such as C<inet_aton> by event-/callback-based versions.
		782
		783	=item L<AnyEvent::Socket>
		784
		785	Provides various utility functions for (internet protocol) sockets,
		786	addresses and name resolution. Also functions to create non-blocking tcp
		787	connections or tcp servers, with IPv6 and SRV record support and more.
		788
		789	=item L<AnyEvent::Handle>
		790
		791	Provide read and write buffers, manages watchers for reads and writes,
		792	supports raw and formatted I/O, I/O queued and fully transparent and
		793	non-blocking SSL/TLS.
		794
		795	=item L<AnyEvent::DNS>
		796
		797	Provides rich asynchronous DNS resolver capabilities.
		798
		799	=item L<AnyEvent::HTTP>
		800
		801	A simple-to-use HTTP library that is capable of making a lot of concurrent
		802	HTTP requests.
		803
		804	=item L<AnyEvent::HTTPD>
		805
		806	Provides a simple web application server framework.
		807
		808	=item L<AnyEvent::FastPing>
		809
		810	The fastest ping in the west.
		811
		812	=item L<AnyEvent::DBI>
		813
		814	Executes L<DBI> requests asynchronously in a proxy process.
		815
		816	=item L<AnyEvent::AIO>
		817
		818	Truly asynchronous I/O, should be in the toolbox of every event
		819	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		820	together.
		821
		822	=item L<AnyEvent::BDB>
		823
		824	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		825	L<BDB> and AnyEvent together.
		826
		827	=item L<AnyEvent::GPSD>
		828
		829	A non-blocking interface to gpsd, a daemon delivering GPS information.
		830
		831	=item L<AnyEvent::IGS>
		832
		833	A non-blocking interface to the Internet Go Server protocol (used by
		834	L<App::IGS>).
		835
		836	=item L<AnyEvent::IRC>
		837
		838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		839
		840	=item L<Net::XMPP2>
		841
		842	AnyEvent based XMPP (Jabber protocol) module family.
		843
		844	=item L<Net::FCP>
		845
		846	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		847	of AnyEvent.
		848
		849	=item L<Event::ExecFlow>
		850
		851	High level API for event-based execution flow control.
		852
		853	=item L<Coro>
		854
		855	Has special support for AnyEvent via L<Coro::AnyEvent>.
		856
		857	=item L<IO::Lambda>
		858
		859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		860
		861	=back
429		862
430	=cut	863	=cut
431		864
432	package AnyEvent;	865	package AnyEvent;
433		866
434	no warnings;	867	no warnings;
435	use strict;	868	use strict qw(vars subs);
436		869
437	use Carp;	870	use Carp;
438		871
439	our $VERSION = '3.3';	872	our $VERSION = 4.341;
440	our $MODEL;	873	our $MODEL;
441		874
442	our $AUTOLOAD;	875	our $AUTOLOAD;
443	our @ISA;	876	our @ISA;
444		877
		878	our @REGISTRY;
		879
		880	our $WIN32;
		881
		882	BEGIN {
		883	my $win32 = ! ! ($^O =~ /mswin32/i);
		884	eval "sub WIN32(){ $win32 }";
		885	}
		886
445	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
446		888
447	our @REGISTRY;	889	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		890
		891	{
		892	my $idx;
		893	$PROTOCOL{$_} = ++$idx
		894	for reverse split /\s*,\s*/,
		895	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		896	}
448		897
449	my @models = (	898	my @models = (
450	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
451	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
452	[EV:: => AnyEvent::Impl::EV::],	899	[EV:: => AnyEvent::Impl::EV::],
453	[Event:: => AnyEvent::Impl::Event::],	900	[Event:: => AnyEvent::Impl::Event::],
454	[Glib:: => AnyEvent::Impl::Glib::],
455	[Tk:: => AnyEvent::Impl::Tk::],
456	[Wx:: => AnyEvent::Impl::POE::],
457	[Prima:: => AnyEvent::Impl::POE::],
458	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
459	# everything below here will not be autoprobed as the pureperl backend should work everywhere	902	# everything below here will not be autoprobed
		903	# as the pureperl backend should work everywhere
		904	# and is usually faster
		905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
460	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
461	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
462	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		910	[Wx:: => AnyEvent::Impl::POE::],
		911	[Prima:: => AnyEvent::Impl::POE::],
463	);	912	);
464		913
465	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	914	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		915
		916	our @post_detect;
		917
		918	sub post_detect(&) {
		919	my ($cb) = @_;
		920
		921	if ($MODEL) {
		922	$cb->();
		923
		924	1
		925	} else {
		926	push @post_detect, $cb;
		927
		928	defined wantarray
		929	? bless \$cb, "AnyEvent::Util::PostDetect"
		930	: ()
		931	}
		932	}
		933
		934	sub AnyEvent::Util::PostDetect::DESTROY {
		935	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		936	}
466		937
467	sub detect() {	938	sub detect() {
468	unless ($MODEL) {	939	unless ($MODEL) {
469	no strict 'refs';	940	no strict 'refs';
		941	local $SIG{__DIE__};
470		942
471	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
472	my $model = "AnyEvent::Impl::$1";	944	my $model = "AnyEvent::Impl::$1";
473	if (eval "require $model") {	945	if (eval "require $model") {
474	$MODEL = $model;	946	$MODEL = $model;
…		…
504	last;	976	last;
505	}	977	}
506	}	978	}
507		979
508	$MODEL	980	$MODEL
509	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
510	}	982	}
511	}	983	}
512		984
		985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		986
513	unshift @ISA, $MODEL;	987	unshift @ISA, $MODEL;
514	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	988
		989	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		990
		991	(shift @post_detect)->() while @post_detect;
515	}	992	}
516		993
517	$MODEL	994	$MODEL
518	}	995	}
519		996
…		…
527		1004
528	my $class = shift;	1005	my $class = shift;
529	$class->$func (@_);	1006	$class->$func (@_);
530	}	1007	}
531		1008
		1009	# utility function to dup a filehandle. this is used by many backends
		1010	# to support binding more than one watcher per filehandle (they usually
		1011	# allow only one watcher per fd, so we dup it to get a different one).
		1012	sub _dupfh($$$$) {
		1013	my ($poll, $fh, $r, $w) = @_;
		1014
		1015	# cygwin requires the fh mode to be matching, unix doesn't
		1016	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1017	: $poll eq "w" ? ($w, ">")
		1018	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1019
		1020	open my $fh2, "$mode&" . fileno $fh
		1021	or die "cannot dup() filehandle: $!";
		1022
		1023	# we assume CLOEXEC is already set by perl in all important cases
		1024
		1025	($fh2, $rw)
		1026	}
		1027
532	package AnyEvent::Base;	1028	package AnyEvent::Base;
533		1029
		1030	# default implementation for now and time
		1031
		1032	BEGIN {
		1033	if (eval "use Time::HiRes (); time (); 1") {
		1034	*_time = \&Time::HiRes::time;
		1035	# if (eval "use POSIX (); (POSIX::times())...
		1036	} else {
		1037	*_time = sub { time }; # epic fail
		1038	}
		1039	}
		1040
		1041	sub time { _time }
		1042	sub now { _time }
		1043
534	# default implementation for ->condvar, ->wait, ->broadcast	1044	# default implementation for ->condvar
535		1045
536	sub condvar {	1046	sub condvar {
537	bless \my $flag, "AnyEvent::Base::CondVar"	1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
538	}
539
540	sub AnyEvent::Base::CondVar::broadcast {
541	${$_[0]}++;
542	}
543
544	sub AnyEvent::Base::CondVar::wait {
545	AnyEvent->one_event while !${$_[0]};
546	}	1048	}
547		1049
548	# default implementation for ->signal	1050	# default implementation for ->signal
549		1051
550	our %SIG_CB;	1052	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1053
		1054	sub _signal_exec {
		1055	sysread $SIGPIPE_R, my $dummy, 4;
		1056
		1057	while (%SIG_EV) {
		1058	for (keys %SIG_EV) {
		1059	delete $SIG_EV{$_};
		1060	$_->() for values %{ $SIG_CB{$_} || {} };
		1061	}
		1062	}
		1063	}
551		1064
552	sub signal {	1065	sub signal {
553	my (undef, %arg) = @_;	1066	my (undef, %arg) = @_;
554		1067
		1068	unless ($SIGPIPE_R) {
		1069	if (AnyEvent::WIN32) {
		1070	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1071	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1072	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1073	} else {
		1074	pipe $SIGPIPE_R, $SIGPIPE_W;
		1075	require Fcntl;
		1076	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1077	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1078	}
		1079
		1080	$SIGPIPE_R
		1081	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1082
		1083	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1084	}
		1085
555	my $signal = uc $arg{signal}	1086	my $signal = uc $arg{signal}
556	or Carp::croak "required option 'signal' is missing";	1087	or Carp::croak "required option 'signal' is missing";
557		1088
558	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1089	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
559	$SIG{$signal} ||= sub {	1090	$SIG{$signal} ||= sub {
560	$_->() for values %{ $SIG_CB{$signal} || {} };	1091	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1092	undef $SIG_EV{$signal};
561	};	1093	};
562		1094
563	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1095	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
564	}	1096	}
565		1097
566	sub AnyEvent::Base::Signal::DESTROY {	1098	sub AnyEvent::Base::Signal::DESTROY {
567	my ($signal, $cb) = @{$_[0]};	1099	my ($signal, $cb) = @{$_[0]};
568		1100
569	delete $SIG_CB{$signal}{$cb};	1101	delete $SIG_CB{$signal}{$cb};
570		1102
571	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1103	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
572	}	1104	}
573		1105
574	# default implementation for ->child	1106	# default implementation for ->child
575		1107
576	our %PID_CB;	1108	our %PID_CB;
…		…
603	or Carp::croak "required option 'pid' is missing";	1135	or Carp::croak "required option 'pid' is missing";
604		1136
605	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1137	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
606		1138
607	unless ($WNOHANG) {	1139	unless ($WNOHANG) {
608	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1140	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
609	}	1141	}
610		1142
611	unless ($CHLD_W) {	1143	unless ($CHLD_W) {
612	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1144	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
613	# child could be a zombie already, so make at least one round	1145	# child could be a zombie already, so make at least one round
…		…
623	delete $PID_CB{$pid}{$cb};	1155	delete $PID_CB{$pid}{$cb};
624	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1156	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
625		1157
626	undef $CHLD_W unless keys %PID_CB;	1158	undef $CHLD_W unless keys %PID_CB;
627	}	1159	}
		1160
		1161	package AnyEvent::CondVar;
		1162
		1163	our @ISA = AnyEvent::CondVar::Base::;
		1164
		1165	package AnyEvent::CondVar::Base;
		1166
		1167	use overload
		1168	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1169	fallback => 1;
		1170
		1171	sub _send {
		1172	# nop
		1173	}
		1174
		1175	sub send {
		1176	my $cv = shift;
		1177	$cv->{_ae_sent} = [@_];
		1178	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1179	$cv->_send;
		1180	}
		1181
		1182	sub croak {
		1183	$_[0]{_ae_croak} = $_[1];
		1184	$_[0]->send;
		1185	}
		1186
		1187	sub ready {
		1188	$_[0]{_ae_sent}
		1189	}
		1190
		1191	sub _wait {
		1192	AnyEvent->one_event while !$_[0]{_ae_sent};
		1193	}
		1194
		1195	sub recv {
		1196	$_[0]->_wait;
		1197
		1198	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1199	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1200	}
		1201
		1202	sub cb {
		1203	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1204	$_[0]{_ae_cb}
		1205	}
		1206
		1207	sub begin {
		1208	++$_[0]{_ae_counter};
		1209	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1210	}
		1211
		1212	sub end {
		1213	return if --$_[0]{_ae_counter};
		1214	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1215	}
		1216
		1217	# undocumented/compatibility with pre-3.4
		1218	*broadcast = \&send;
		1219	*wait = \&_wait;
		1220
		1221	=head1 ERROR AND EXCEPTION HANDLING
		1222
		1223	In general, AnyEvent does not do any error handling - it relies on the
		1224	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1225	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1226	checking of all AnyEvent methods, however, which is highly useful during
		1227	development.
		1228
		1229	As for exception handling (i.e. runtime errors and exceptions thrown while
		1230	executing a callback), this is not only highly event-loop specific, but
		1231	also not in any way wrapped by this module, as this is the job of the main
		1232	program.
		1233
		1234	The pure perl event loop simply re-throws the exception (usually
		1235	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1236	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1237	so on.
		1238
		1239	=head1 ENVIRONMENT VARIABLES
		1240
		1241	The following environment variables are used by this module or its
		1242	submodules:
		1243
		1244	=over 4
		1245
		1246	=item C<PERL_ANYEVENT_VERBOSE>
		1247
		1248	By default, AnyEvent will be completely silent except in fatal
		1249	conditions. You can set this environment variable to make AnyEvent more
		1250	talkative.
		1251
		1252	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1253	conditions, such as not being able to load the event model specified by
		1254	C<PERL_ANYEVENT_MODEL>.
		1255
		1256	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1257	model it chooses.
		1258
		1259	=item C<PERL_ANYEVENT_STRICT>
		1260
		1261	AnyEvent does not do much argument checking by default, as thorough
		1262	argument checking is very costly. Setting this variable to a true value
		1263	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1264	check the arguments passed to most method calls. If it finds any problems
		1265	it will croak.
		1266
		1267	In other words, enables "strict" mode.
		1268
		1269	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1270	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1271	developing programs can be very useful, however.
		1272
		1273	=item C<PERL_ANYEVENT_MODEL>
		1274
		1275	This can be used to specify the event model to be used by AnyEvent, before
		1276	auto detection and -probing kicks in. It must be a string consisting
		1277	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1278	and the resulting module name is loaded and if the load was successful,
		1279	used as event model. If it fails to load AnyEvent will proceed with
		1280	auto detection and -probing.
		1281
		1282	This functionality might change in future versions.
		1283
		1284	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1285	could start your program like this:
		1286
		1287	PERL_ANYEVENT_MODEL=Perl perl ...
		1288
		1289	=item C<PERL_ANYEVENT_PROTOCOLS>
		1290
		1291	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1292	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1293	of auto probing).
		1294
		1295	Must be set to a comma-separated list of protocols or address families,
		1296	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1297	used, and preference will be given to protocols mentioned earlier in the
		1298	list.
		1299
		1300	This variable can effectively be used for denial-of-service attacks
		1301	against local programs (e.g. when setuid), although the impact is likely
		1302	small, as the program has to handle conenction and other failures anyways.
		1303
		1304	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1305	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1306	- only support IPv4, never try to resolve or contact IPv6
		1307	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1308	IPv6, but prefer IPv6 over IPv4.
		1309
		1310	=item C<PERL_ANYEVENT_EDNS0>
		1311
		1312	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1313	for DNS. This extension is generally useful to reduce DNS traffic, but
		1314	some (broken) firewalls drop such DNS packets, which is why it is off by
		1315	default.
		1316
		1317	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1318	EDNS0 in its DNS requests.
		1319
		1320	=item C<PERL_ANYEVENT_MAX_FORKS>
		1321
		1322	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1323	will create in parallel.
		1324
		1325	=back
628		1326
629	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1327	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
630		1328
631	This is an advanced topic that you do not normally need to use AnyEvent in	1329	This is an advanced topic that you do not normally need to use AnyEvent in
632	a module. This section is only of use to event loop authors who want to	1330	a module. This section is only of use to event loop authors who want to
…		…
667	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1365	I<rxvt-unicode> also cheats a bit by not providing blocking access to
668	condition variables: code blocking while waiting for a condition will	1366	condition variables: code blocking while waiting for a condition will
669	C<die>. This still works with most modules/usages, and blocking calls must	1367	C<die>. This still works with most modules/usages, and blocking calls must
670	not be done in an interactive application, so it makes sense.	1368	not be done in an interactive application, so it makes sense.
671		1369
672	=head1 ENVIRONMENT VARIABLES
673
674	The following environment variables are used by this module:
675
676	=over 4
677
678	=item C<PERL_ANYEVENT_VERBOSE>
679
680	By default, AnyEvent will be completely silent except in fatal
681	conditions. You can set this environment variable to make AnyEvent more
682	talkative.
683
684	When set to C<1> or higher, causes AnyEvent to warn about unexpected
685	conditions, such as not being able to load the event model specified by
686	C<PERL_ANYEVENT_MODEL>.
687
688	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
689	model it chooses.
690
691	=item C<PERL_ANYEVENT_MODEL>
692
693	This can be used to specify the event model to be used by AnyEvent, before
694	autodetection and -probing kicks in. It must be a string consisting
695	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
696	and the resulting module name is loaded and if the load was successful,
697	used as event model. If it fails to load AnyEvent will proceed with
698	autodetection and -probing.
699
700	This functionality might change in future versions.
701
702	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
703	could start your program like this:
704
705	PERL_ANYEVENT_MODEL=Perl perl ...
706
707	=back
708
709	=head1 EXAMPLE PROGRAM	1370	=head1 EXAMPLE PROGRAM
710		1371
711	The following program uses an IO watcher to read data from STDIN, a timer	1372	The following program uses an I/O watcher to read data from STDIN, a timer
712	to display a message once per second, and a condition variable to quit the	1373	to display a message once per second, and a condition variable to quit the
713	program when the user enters quit:	1374	program when the user enters quit:
714		1375
715	use AnyEvent;	1376	use AnyEvent;
716		1377
…		…
721	poll => 'r',	1382	poll => 'r',
722	cb => sub {	1383	cb => sub {
723	warn "io event <$_[0]>\n"; # will always output <r>	1384	warn "io event <$_[0]>\n"; # will always output <r>
724	chomp (my $input = <STDIN>); # read a line	1385	chomp (my $input = <STDIN>); # read a line
725	warn "read: $input\n"; # output what has been read	1386	warn "read: $input\n"; # output what has been read
726	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1387	$cv->send if $input =~ /^q/i; # quit program if /^q/i
727	},	1388	},
728	);	1389	);
729		1390
730	my $time_watcher; # can only be used once	1391	my $time_watcher; # can only be used once
731		1392
…		…
736	});	1397	});
737	}	1398	}
738		1399
739	new_timer; # create first timer	1400	new_timer; # create first timer
740		1401
741	$cv->wait; # wait until user enters /^q/i	1402	$cv->recv; # wait until user enters /^q/i
742		1403
743	=head1 REAL-WORLD EXAMPLE	1404	=head1 REAL-WORLD EXAMPLE
744		1405
745	Consider the L<Net::FCP> module. It features (among others) the following	1406	Consider the L<Net::FCP> module. It features (among others) the following
746	API calls, which are to freenet what HTTP GET requests are to http:	1407	API calls, which are to freenet what HTTP GET requests are to http:
…		…
796	syswrite $txn->{fh}, $txn->{request}	1457	syswrite $txn->{fh}, $txn->{request}
797	or die "connection or write error";	1458	or die "connection or write error";
798	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1459	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
799		1460
800	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1461	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
801	result and signals any possible waiters that the request ahs finished:	1462	result and signals any possible waiters that the request has finished:
802		1463
803	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1464	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
804		1465
805	if (end-of-file or data complete) {	1466	if (end-of-file or data complete) {
806	$txn->{result} = $txn->{buf};	1467	$txn->{result} = $txn->{buf};
807	$txn->{finished}->broadcast;	1468	$txn->{finished}->send;
808	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1469	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
809	}	1470	}
810		1471
811	The C<result> method, finally, just waits for the finished signal (if the	1472	The C<result> method, finally, just waits for the finished signal (if the
812	request was already finished, it doesn't wait, of course, and returns the	1473	request was already finished, it doesn't wait, of course, and returns the
813	data:	1474	data:
814		1475
815	$txn->{finished}->wait;	1476	$txn->{finished}->recv;
816	return $txn->{result};	1477	return $txn->{result};
817		1478
818	The actual code goes further and collects all errors (C<die>s, exceptions)	1479	The actual code goes further and collects all errors (C<die>s, exceptions)
819	that occured during request processing. The C<result> method detects	1480	that occurred during request processing. The C<result> method detects
820	whether an exception as thrown (it is stored inside the $txn object)	1481	whether an exception as thrown (it is stored inside the $txn object)
821	and just throws the exception, which means connection errors and other	1482	and just throws the exception, which means connection errors and other
822	problems get reported tot he code that tries to use the result, not in a	1483	problems get reported tot he code that tries to use the result, not in a
823	random callback.	1484	random callback.
824		1485
…		…
855		1516
856	my $quit = AnyEvent->condvar;	1517	my $quit = AnyEvent->condvar;
857		1518
858	$fcp->txn_client_get ($url)->cb (sub {	1519	$fcp->txn_client_get ($url)->cb (sub {
859	...	1520	...
860	$quit->broadcast;	1521	$quit->send;
861	});	1522	});
862		1523
863	$quit->wait;	1524	$quit->recv;
864		1525
865		1526
866	=head1 BENCHMARK	1527	=head1 BENCHMARKS
867		1528
868	To give you an idea of the performance and overheads that AnyEvent adds	1529	To give you an idea of the performance and overheads that AnyEvent adds
869	over the event loops themselves (and to give you an impression of the	1530	over the event loops themselves and to give you an impression of the speed
870	speed of various event loops), here is a benchmark of various supported	1531	of various event loops I prepared some benchmarks.
871	event models natively and with anyevent. The benchmark creates a lot of	1532
872	timers (with a zero timeout) and io watchers (watching STDOUT, a pty, to	1533	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1534
		1535	Here is a benchmark of various supported event models used natively and
		1536	through AnyEvent. The benchmark creates a lot of timers (with a zero
		1537	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
873	become writable, which it is), lets them fire exactly once and destroys	1538	which it is), lets them fire exactly once and destroys them again.
874	them again.
875		1539
		1540	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
		1541	distribution.
		1542
876	=head2 Explanation of the columns	1543	=head3 Explanation of the columns
877		1544
878	I<watcher> is the number of event watchers created/destroyed. Since	1545	I<watcher> is the number of event watchers created/destroyed. Since
879	different event models feature vastly different performances, each event	1546	different event models feature vastly different performances, each event
880	loop was given a number of watchers so that overall runtime is acceptable	1547	loop was given a number of watchers so that overall runtime is acceptable
881	and similar between tested event loop (and keep them from crashing): Glib	1548	and similar between tested event loop (and keep them from crashing): Glib
…		…
891	all watchers, to avoid adding memory overhead. That means closure creation	1558	all watchers, to avoid adding memory overhead. That means closure creation
892	and memory usage is not included in the figures.	1559	and memory usage is not included in the figures.
893		1560
894	I<invoke> is the time, in microseconds, used to invoke a simple	1561	I<invoke> is the time, in microseconds, used to invoke a simple
895	callback. The callback simply counts down a Perl variable and after it was	1562	callback. The callback simply counts down a Perl variable and after it was
896	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1563	invoked "watcher" times, it would C<< ->send >> a condvar once to
897	signal the end of this phase.	1564	signal the end of this phase.
898		1565
899	I<destroy> is the time, in microseconds, that it takes to destroy a single	1566	I<destroy> is the time, in microseconds, that it takes to destroy a single
900	watcher.	1567	watcher.
901		1568
902	=head2 Results	1569	=head3 Results
903		1570
904	name watchers bytes create invoke destroy comment	1571	name watchers bytes create invoke destroy comment
905	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1572	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
906	EV/Any 100000 610 3.52 0.91 0.75 EV + AnyEvent watchers	1573	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
907	CoroEV/Any 100000 610 3.49 0.92 0.75 coroutines + Coro::Signal	1574	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
908	Perl/Any 100000 513 4.91 0.92 1.15 pure perl implementation	1575	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
909	Event/Event 16000 523 28.05 21.38 0.86 Event native interface	1576	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
910	Event/Any 16000 943 34.43 20.48 1.39 Event + AnyEvent watchers	1577	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
911	Glib/Any 16000 1357 96.99 12.55 55.51 quadratic behaviour	1578	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
912	Tk/Any 2000 1855 27.01 66.61 14.03 SEGV with >> 2000 watchers	1579	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
913	POE/Event 2000 6644 108.15 768.19 14.33 via POE::Loop::Event	1580	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
914	POE/Select 2000 6343 94.69 807.65 562.69 via POE::Loop::Select	1581	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
915		1582
916	=head2 Discussion	1583	=head3 Discussion
917		1584
918	The benchmark does I<not> measure scalability of the event loop very	1585	The benchmark does I<not> measure scalability of the event loop very
919	well. For example, a select-based event loop (such as the pure perl one)	1586	well. For example, a select-based event loop (such as the pure perl one)
920	can never compete with an event loop that uses epoll when the number of	1587	can never compete with an event loop that uses epoll when the number of
921	file descriptors grows high. In this benchmark, only a single filehandle	1588	file descriptors grows high. In this benchmark, all events become ready at
922	is used (although some of the AnyEvent adaptors dup() its file descriptor	1589	the same time, so select/poll-based implementations get an unnatural speed
923	to worka round bugs).	1590	boost.
		1591
		1592	Also, note that the number of watchers usually has a nonlinear effect on
		1593	overall speed, that is, creating twice as many watchers doesn't take twice
		1594	the time - usually it takes longer. This puts event loops tested with a
		1595	higher number of watchers at a disadvantage.
		1596
		1597	To put the range of results into perspective, consider that on the
		1598	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1599	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1600	cycles with POE.
924		1601
925	C<EV> is the sole leader regarding speed and memory use, which are both	1602	C<EV> is the sole leader regarding speed and memory use, which are both
926	maximal/minimal, respectively. Even when going through AnyEvent, there are	1603	maximal/minimal, respectively. Even when going through AnyEvent, it uses
927	only two event loops that use slightly less memory (the C<Event> module	1604	far less memory than any other event loop and is still faster than Event
928	natively and the pure perl backend), and no faster event models, not even	1605	natively.
929	C<Event> natively.
930		1606
931	The pure perl implementation is hit in a few sweet spots (both the	1607	The pure perl implementation is hit in a few sweet spots (both the
932	zero timeout and the use of a single fd hit optimisations in the perl	1608	constant timeout and the use of a single fd hit optimisations in the perl
933	interpreter and the backend itself). Nevertheless tis shows that it	1609	interpreter and the backend itself). Nevertheless this shows that it
934	adds very little overhead in itself. Like any select-based backend its	1610	adds very little overhead in itself. Like any select-based backend its
935	performance becomes really bad with lots of file descriptors, of course,	1611	performance becomes really bad with lots of file descriptors (and few of
936	but this was not subject of this benchmark.	1612	them active), of course, but this was not subject of this benchmark.
937		1613
938	The C<Event> module has a relatively high setup and callback invocation cost,	1614	The C<Event> module has a relatively high setup and callback invocation
939	but overall scores on the third place.	1615	cost, but overall scores in on the third place.
940		1616
941	C<Glib>'s memory usage is quite a bit bit higher, but it features a	1617	C<Glib>'s memory usage is quite a bit higher, but it features a
942	faster callback invocation and overall ends up in the same class as	1618	faster callback invocation and overall ends up in the same class as
943	C<Event>. However, Glib scales extremely badly, doubling the number of	1619	C<Event>. However, Glib scales extremely badly, doubling the number of
944	watchers increases the processing time by more than a factor of four,	1620	watchers increases the processing time by more than a factor of four,
945	making it completely unusable when using larger numbers of watchers	1621	making it completely unusable when using larger numbers of watchers
946	(note that only a single file descriptor was used in the benchmark, so	1622	(note that only a single file descriptor was used in the benchmark, so
…		…
949	The C<Tk> adaptor works relatively well. The fact that it crashes with	1625	The C<Tk> adaptor works relatively well. The fact that it crashes with
950	more than 2000 watchers is a big setback, however, as correctness takes	1626	more than 2000 watchers is a big setback, however, as correctness takes
951	precedence over speed. Nevertheless, its performance is surprising, as the	1627	precedence over speed. Nevertheless, its performance is surprising, as the
952	file descriptor is dup()ed for each watcher. This shows that the dup()	1628	file descriptor is dup()ed for each watcher. This shows that the dup()
953	employed by some adaptors is not a big performance issue (it does incur a	1629	employed by some adaptors is not a big performance issue (it does incur a
954	hidden memory cost inside the kernel, though, that is not reflected in the	1630	hidden memory cost inside the kernel which is not reflected in the figures
955	figures above).	1631	above).
956		1632
957	C<POE>, regardless of underlying event loop (wether using its pure perl	1633	C<POE>, regardless of underlying event loop (whether using its pure perl
958	select-based backend or the Event module) shows abysmal performance and	1634	select-based backend or the Event module, the POE-EV backend couldn't
		1635	be tested because it wasn't working) shows abysmal performance and
959	memory usage: Watchers use almost 30 times as much memory as EV watchers,	1636	memory usage with AnyEvent: Watchers use almost 30 times as much memory
960	and 10 times as much memory as both Event or EV via AnyEvent. Watcher	1637	as EV watchers, and 10 times as much memory as Event (the high memory
		1638	requirements are caused by requiring a session for each watcher). Watcher
961	invocation is almost 700 times slower than with AnyEvent's pure perl	1639	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1640	implementation.
		1641
962	implementation. The design of the POE adaptor class in AnyEvent can not	1642	The design of the POE adaptor class in AnyEvent can not really account
963	really account for this, as session creation overhead is small compared	1643	for the performance issues, though, as session creation overhead is
964	to execution of the state machine, which is coded pretty optimally within	1644	small compared to execution of the state machine, which is coded pretty
965	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1645	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1646	using multiple sessions is not a good approach, especially regarding
		1647	memory usage, even the author of POE could not come up with a faster
		1648	design).
966		1649
967	=head2 Summary	1650	=head3 Summary
968		1651
		1652	=over 4
		1653
969	Using EV through AnyEvent is faster than any other event loop, but most	1654	=item * Using EV through AnyEvent is faster than any other event loop
970	event loops have acceptable performance with or without AnyEvent.	1655	(even when used without AnyEvent), but most event loops have acceptable
		1656	performance with or without AnyEvent.
971		1657
972	The overhead AnyEvent adds is usually much smaller than the overhead of	1658	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
973	the actual event loop, only with extremely fast event loops such as the EV	1659	the actual event loop, only with extremely fast event loops such as EV
974	adds AnyEvent significant overhead.	1660	adds AnyEvent significant overhead.
975		1661
976	And you should simply avoid POE like the plague if you want performance or	1662	=item * You should avoid POE like the plague if you want performance or
977	reasonable memory usage.	1663	reasonable memory usage.
978		1664
		1665	=back
		1666
		1667	=head2 BENCHMARKING THE LARGE SERVER CASE
		1668
		1669	This benchmark actually benchmarks the event loop itself. It works by
		1670	creating a number of "servers": each server consists of a socket pair, a
		1671	timeout watcher that gets reset on activity (but never fires), and an I/O
		1672	watcher waiting for input on one side of the socket. Each time the socket
		1673	watcher reads a byte it will write that byte to a random other "server".
		1674
		1675	The effect is that there will be a lot of I/O watchers, only part of which
		1676	are active at any one point (so there is a constant number of active
		1677	fds for each loop iteration, but which fds these are is random). The
		1678	timeout is reset each time something is read because that reflects how
		1679	most timeouts work (and puts extra pressure on the event loops).
		1680
		1681	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		1682	(1%) are active. This mirrors the activity of large servers with many
		1683	connections, most of which are idle at any one point in time.
		1684
		1685	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		1686	distribution.
		1687
		1688	=head3 Explanation of the columns
		1689
		1690	I<sockets> is the number of sockets, and twice the number of "servers" (as
		1691	each server has a read and write socket end).
		1692
		1693	I<create> is the time it takes to create a socket pair (which is
		1694	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		1695
		1696	I<request>, the most important value, is the time it takes to handle a
		1697	single "request", that is, reading the token from the pipe and forwarding
		1698	it to another server. This includes deleting the old timeout and creating
		1699	a new one that moves the timeout into the future.
		1700
		1701	=head3 Results
		1702
		1703	name sockets create request
		1704	EV 20000 69.01 11.16
		1705	Perl 20000 73.32 35.87
		1706	Event 20000 212.62 257.32
		1707	Glib 20000 651.16 1896.30
		1708	POE 20000 349.67 12317.24 uses POE::Loop::Event
		1709
		1710	=head3 Discussion
		1711
		1712	This benchmark I<does> measure scalability and overall performance of the
		1713	particular event loop.
		1714
		1715	EV is again fastest. Since it is using epoll on my system, the setup time
		1716	is relatively high, though.
		1717
		1718	Perl surprisingly comes second. It is much faster than the C-based event
		1719	loops Event and Glib.
		1720
		1721	Event suffers from high setup time as well (look at its code and you will
		1722	understand why). Callback invocation also has a high overhead compared to
		1723	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		1724	uses select or poll in basically all documented configurations.
		1725
		1726	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		1727	clearly fails to perform with many filehandles or in busy servers.
		1728
		1729	POE is still completely out of the picture, taking over 1000 times as long
		1730	as EV, and over 100 times as long as the Perl implementation, even though
		1731	it uses a C-based event loop in this case.
		1732
		1733	=head3 Summary
		1734
		1735	=over 4
		1736
		1737	=item * The pure perl implementation performs extremely well.
		1738
		1739	=item * Avoid Glib or POE in large projects where performance matters.
		1740
		1741	=back
		1742
		1743	=head2 BENCHMARKING SMALL SERVERS
		1744
		1745	While event loops should scale (and select-based ones do not...) even to
		1746	large servers, most programs we (or I :) actually write have only a few
		1747	I/O watchers.
		1748
		1749	In this benchmark, I use the same benchmark program as in the large server
		1750	case, but it uses only eight "servers", of which three are active at any
		1751	one time. This should reflect performance for a small server relatively
		1752	well.
		1753
		1754	The columns are identical to the previous table.
		1755
		1756	=head3 Results
		1757
		1758	name sockets create request
		1759	EV 16 20.00 6.54
		1760	Perl 16 25.75 12.62
		1761	Event 16 81.27 35.86
		1762	Glib 16 32.63 15.48
		1763	POE 16 261.87 276.28 uses POE::Loop::Event
		1764
		1765	=head3 Discussion
		1766
		1767	The benchmark tries to test the performance of a typical small
		1768	server. While knowing how various event loops perform is interesting, keep
		1769	in mind that their overhead in this case is usually not as important, due
		1770	to the small absolute number of watchers (that is, you need efficiency and
		1771	speed most when you have lots of watchers, not when you only have a few of
		1772	them).
		1773
		1774	EV is again fastest.
		1775
		1776	Perl again comes second. It is noticeably faster than the C-based event
		1777	loops Event and Glib, although the difference is too small to really
		1778	matter.
		1779
		1780	POE also performs much better in this case, but is is still far behind the
		1781	others.
		1782
		1783	=head3 Summary
		1784
		1785	=over 4
		1786
		1787	=item * C-based event loops perform very well with small number of
		1788	watchers, as the management overhead dominates.
		1789
		1790	=back
		1791
		1792
		1793	=head1 SIGNALS
		1794
		1795	AnyEvent currently installs handlers for these signals:
		1796
		1797	=over 4
		1798
		1799	=item SIGCHLD
		1800
		1801	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1802	emulation for event loops that do not support them natively. Also, some
		1803	event loops install a similar handler.
		1804
		1805	=item SIGPIPE
		1806
		1807	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1808	when AnyEvent gets loaded.
		1809
		1810	The rationale for this is that AnyEvent users usually do not really depend
		1811	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1812	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1813	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1814	some random socket.
		1815
		1816	The rationale for installing a no-op handler as opposed to ignoring it is
		1817	that this way, the handler will be restored to defaults on exec.
		1818
		1819	Feel free to install your own handler, or reset it to defaults.
		1820
		1821	=back
		1822
		1823	=cut
		1824
		1825	$SIG{PIPE} = sub { }
		1826	unless defined $SIG{PIPE};
		1827
979		1828
980	=head1 FORK	1829	=head1 FORK
981		1830
982	Most event libraries are not fork-safe. The ones who are usually are	1831	Most event libraries are not fork-safe. The ones who are usually are
983	because they are so inefficient. Only L<EV> is fully fork-aware.	1832	because they rely on inefficient but fork-safe C<select> or C<poll>
		1833	calls. Only L<EV> is fully fork-aware.
984		1834
985	If you have to fork, you must either do so I<before> creating your first	1835	If you have to fork, you must either do so I<before> creating your first
986	watcher OR you must not use AnyEvent at all in the child.	1836	watcher OR you must not use AnyEvent at all in the child.
987		1837
988		1838
…		…
996	specified in the variable.	1846	specified in the variable.
997		1847
998	You can make AnyEvent completely ignore this variable by deleting it	1848	You can make AnyEvent completely ignore this variable by deleting it
999	before the first watcher gets created, e.g. with a C<BEGIN> block:	1849	before the first watcher gets created, e.g. with a C<BEGIN> block:
1000		1850
1001	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1851	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1002		1852
1003	use AnyEvent;	1853	use AnyEvent;
		1854
		1855	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1856	be used to probe what backend is used and gain other information (which is
		1857	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1858	$ENV{PERL_ANYEGENT_STRICT}.
		1859
		1860
		1861	=head1 BUGS
		1862
		1863	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1864	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1865	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1866	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1867	pronounced).
1004		1868
1005		1869
1006	=head1 SEE ALSO	1870	=head1 SEE ALSO
1007		1871
1008	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1872	Utility functions: L<AnyEvent::Util>.
1009	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1873
		1874	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1010	L<Event::Lib>, L<Qt>, L<POE>.	1875	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1011		1876
1012	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1877	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1013	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1878	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1014	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1879	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1015	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1880	L<AnyEvent::Impl::POE>.
1016		1881
		1882	Non-blocking file handles, sockets, TCP clients and
		1883	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1884
		1885	Asynchronous DNS: L<AnyEvent::DNS>.
		1886
		1887	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1888
1017	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1889	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1018		1890
1019		1891
1020	=head1 AUTHOR	1892	=head1 AUTHOR
1021		1893
1022	Marc Lehmann <schmorp@schmorp.de>	1894	Marc Lehmann <schmorp@schmorp.de>
1023	http://home.schmorp.de/	1895	http://home.schmorp.de/
1024		1896
1025	=cut	1897	=cut
1026		1898
1027	1	1899	1
1028		1900

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