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Revision 1.200 by root, Wed Apr 1 14:02:27 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		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
…		…
78	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
79	module.	101	module.
80		102
81	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
82	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
86	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
88	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
114		136
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
118	is in control).	140	is in control).
119		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
120	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
121	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
122	to it).	150	to it).
123		151
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		156
129	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
130		158
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
133	undef $w;	161	undef $w;
134	});	162	});
135		163
136	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,
137	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
138	declared.	166	declared.
139		167
140	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
141		169
142	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
143	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
144		172
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	173	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		174	for events (AnyEvent might or might not keep a reference to this file
		175	handle). Note that only file handles pointing to things for which
		176	non-blocking operation makes sense are allowed. This includes sockets,
		177	most character devices, pipes, fifos and so on, but not for example files
		178	or block devices.
		179
146	for events. C<poll> must be a string that is either C<r> or C<w>,	180	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
148	respectively. C<cb> is the callback to invoke each time the file handle	183	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		184
151	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
154		188
…		…
158		192
159	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	194	always use non-blocking calls when reading/writing from/to your file
161	handles.	195	handles.
162		196
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	197	Example: wait for readability of STDIN, then read a line and disable the
		198	watcher.
		199
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	202	warn "read: $input\n";
169	undef $w;	203	undef $w;
170	});	204	});
…		…
180		214
181	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
184		218
185	The timer callback will be invoked at most once: if you want a repeating	219	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	220	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	221	callback will be invoked regularly at that interval (in fractional
		222	seconds) after the first invocation. If C<interval> is specified with a
		223	false value, then it is treated as if it were missing.
188		224
189	Example:	225	The callback will be rescheduled before invoking the callback, but no
		226	attempt is done to avoid timer drift in most backends, so the interval is
		227	only approximate.
190		228
191	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	232	warn "timeout\n";
194	});	233	});
195		234
196	# to cancel the timer:	235	# to cancel the timer:
197	undef $w;	236	undef $w;
198		237
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	238	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		239
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
207	};	242	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		243
212	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
213		245
214	There are two ways to handle timers: based on real time (relative, "fire	246	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	247	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	259	timers.
228		260
229	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	262	AnyEvent API.
231		263
		264	AnyEvent has two additional methods that return the "current time":
		265
		266	=over 4
		267
		268	=item AnyEvent->time
		269
		270	This returns the "current wallclock time" as a fractional number of
		271	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		272	return, and the result is guaranteed to be compatible with those).
		273
		274	It progresses independently of any event loop processing, i.e. each call
		275	will check the system clock, which usually gets updated frequently.
		276
		277	=item AnyEvent->now
		278
		279	This also returns the "current wallclock time", but unlike C<time>, above,
		280	this value might change only once per event loop iteration, depending on
		281	the event loop (most return the same time as C<time>, above). This is the
		282	time that AnyEvent's timers get scheduled against.
		283
		284	I<In almost all cases (in all cases if you don't care), this is the
		285	function to call when you want to know the current time.>
		286
		287	This function is also often faster then C<< AnyEvent->time >>, and
		288	thus the preferred method if you want some timestamp (for example,
		289	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		290
		291	The rest of this section is only of relevance if you try to be very exact
		292	with your timing, you can skip it without bad conscience.
		293
		294	For a practical example of when these times differ, consider L<Event::Lib>
		295	and L<EV> and the following set-up:
		296
		297	The event loop is running and has just invoked one of your callback at
		298	time=500 (assume no other callbacks delay processing). In your callback,
		299	you wait a second by executing C<sleep 1> (blocking the process for a
		300	second) and then (at time=501) you create a relative timer that fires
		301	after three seconds.
		302
		303	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		304	both return C<501>, because that is the current time, and the timer will
		305	be scheduled to fire at time=504 (C<501> + C<3>).
		306
		307	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		308	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		309	last event processing phase started. With L<EV>, your timer gets scheduled
		310	to run at time=503 (C<500> + C<3>).
		311
		312	In one sense, L<Event::Lib> is more exact, as it uses the current time
		313	regardless of any delays introduced by event processing. However, most
		314	callbacks do not expect large delays in processing, so this causes a
		315	higher drift (and a lot more system calls to get the current time).
		316
		317	In another sense, L<EV> is more exact, as your timer will be scheduled at
		318	the same time, regardless of how long event processing actually took.
		319
		320	In either case, if you care (and in most cases, you don't), then you
		321	can get whatever behaviour you want with any event loop, by taking the
		322	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		323	account.
		324
		325	=back
		326
232	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
233		328
234	You can watch for signals using a signal watcher, C<signal> is the signal	329	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	330	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
237		332
238	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
241		336
242	Multiple signal occurances can be clumped together into one callback	337	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	338	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	339	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	340	but it is guaranteed not to interrupt any other callbacks.
246		341
247	The main advantage of using these watchers is that you can share a signal	342	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	343	between multiple watchers.
249		344
250	This watcher might use C<%SIG>, so programs overwriting those signals	345	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
258		353
259	You can also watch on a child process exit and catch its exit status.	354	You can also watch on a child process exit and catch its exit status.
260		355
261	The child process is specified by the C<pid> argument (if set to C<0>, it	356	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	357	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	358	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	359	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	360
266	you I<can> rely on child watcher callback arguments.	361	The callback will be called with the pid and exit status (as returned by
		362	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		363	callback arguments.
		364
		365	This watcher type works by installing a signal handler for C<SIGCHLD>,
		366	and since it cannot be shared, nothing else should use SIGCHLD or reap
		367	random child processes (waiting for specific child processes, e.g. inside
		368	C<system>, is just fine).
267		369
268	There is a slight catch to child watchers, however: you usually start them	370	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	371	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
271		373
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	379	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		381
280	Example: fork a process and wait for it	382	Example: fork a process and wait for it
281		383
282	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
283		385
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
287		387
288	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
289	pid => $pid,	389	pid => $pid,
290	cb => sub {	390	cb => sub {
291	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
293	$done->broadcast;	393	$done->send;
294	},	394	},
295	);	395	);
296		396
297	# do something else, then wait for process exit	397	# do something else, then wait for process exit
298	$done->wait;	398	$done->recv;
299		399
300	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
301		401
		402	If you are familiar with some event loops you will know that all of them
		403	require you to run some blocking "loop", "run" or similar function that
		404	will actively watch for new events and call your callbacks.
		405
		406	AnyEvent is different, it expects somebody else to run the event loop and
		407	will only block when necessary (usually when told by the user).
		408
		409	The instrument to do that is called a "condition variable", so called
		410	because they represent a condition that must become true.
		411
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	412	Condition variables can be created by calling the C<< AnyEvent->condvar
303	method without any arguments.	413	>> method, usually without arguments. The only argument pair allowed is
304		414
305	A condition variable waits for a condition - precisely that the C<<	415	C<cb>, which specifies a callback to be called when the condition variable
306	->broadcast >> method has been called.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
307		418
308	They are very useful to signal that a condition has been fulfilled, for	419	After creation, the condition variable is "false" until it becomes "true"
		420	by calling the C<send> method (or calling the condition variable as if it
		421	were a callback, read about the caveats in the description for the C<<
		422	->send >> method).
		423
		424	Condition variables are similar to callbacks, except that you can
		425	optionally wait for them. They can also be called merge points - points
		426	in time where multiple outstanding events have been processed. And yet
		427	another way to call them is transactions - each condition variable can be
		428	used to represent a transaction, which finishes at some point and delivers
		429	a result.
		430
		431	Condition variables are very useful to signal that something has finished,
309	example, if you write a module that does asynchronous http requests,	432	for example, if you write a module that does asynchronous http requests,
310	then a condition variable would be the ideal candidate to signal the	433	then a condition variable would be the ideal candidate to signal the
311	availability of results.	434	availability of results. The user can either act when the callback is
		435	called or can synchronously C<< ->recv >> for the results.
312		436
313	You can also use condition variables to block your main program until	437	You can also use them to simulate traditional event loops - for example,
314	an event occurs - for example, you could C<< ->wait >> in your main	438	you can block your main program until an event occurs - for example, you
315	program until the user clicks the Quit button in your app, which would C<<	439	could C<< ->recv >> in your main program until the user clicks the Quit
316	->broadcast >> the "quit" event.	440	button of your app, which would C<< ->send >> the "quit" event.
317		441
318	Note that condition variables recurse into the event loop - if you have	442	Note that condition variables recurse into the event loop - if you have
319	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	443	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
320	lose. Therefore, condition variables are good to export to your caller, but	444	lose. Therefore, condition variables are good to export to your caller, but
321	you should avoid making a blocking wait yourself, at least in callbacks,	445	you should avoid making a blocking wait yourself, at least in callbacks,
322	as this asks for trouble.	446	as this asks for trouble.
323		447
324	This object has two methods:	448	Condition variables are represented by hash refs in perl, and the keys
		449	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		450	easy (it is often useful to build your own transaction class on top of
		451	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		452	it's C<new> method in your own C<new> method.
		453
		454	There are two "sides" to a condition variable - the "producer side" which
		455	eventually calls C<< -> send >>, and the "consumer side", which waits
		456	for the send to occur.
		457
		458	Example: wait for a timer.
		459
		460	# wait till the result is ready
		461	my $result_ready = AnyEvent->condvar;
		462
		463	# do something such as adding a timer
		464	# or socket watcher the calls $result_ready->send
		465	# when the "result" is ready.
		466	# in this case, we simply use a timer:
		467	my $w = AnyEvent->timer (
		468	after => 1,
		469	cb => sub { $result_ready->send },
		470	);
		471
		472	# this "blocks" (while handling events) till the callback
		473	# calls send
		474	$result_ready->recv;
		475
		476	Example: wait for a timer, but take advantage of the fact that
		477	condition variables are also code references.
		478
		479	my $done = AnyEvent->condvar;
		480	my $delay = AnyEvent->timer (after => 5, cb => $done);
		481	$done->recv;
		482
		483	Example: Imagine an API that returns a condvar and doesn't support
		484	callbacks. This is how you make a synchronous call, for example from
		485	the main program:
		486
		487	use AnyEvent::CouchDB;
		488
		489	...
		490
		491	my @info = $couchdb->info->recv;
		492
		493	And this is how you would just ste a callback to be called whenever the
		494	results are available:
		495
		496	$couchdb->info->cb (sub {
		497	my @info = $_[0]->recv;
		498	});
		499
		500	=head3 METHODS FOR PRODUCERS
		501
		502	These methods should only be used by the producing side, i.e. the
		503	code/module that eventually sends the signal. Note that it is also
		504	the producer side which creates the condvar in most cases, but it isn't
		505	uncommon for the consumer to create it as well.
325		506
326	=over 4	507	=over 4
327		508
		509	=item $cv->send (...)
		510
		511	Flag the condition as ready - a running C<< ->recv >> and all further
		512	calls to C<recv> will (eventually) return after this method has been
		513	called. If nobody is waiting the send will be remembered.
		514
		515	If a callback has been set on the condition variable, it is called
		516	immediately from within send.
		517
		518	Any arguments passed to the C<send> call will be returned by all
		519	future C<< ->recv >> calls.
		520
		521	Condition variables are overloaded so one can call them directly
		522	(as a code reference). Calling them directly is the same as calling
		523	C<send>. Note, however, that many C-based event loops do not handle
		524	overloading, so as tempting as it may be, passing a condition variable
		525	instead of a callback does not work. Both the pure perl and EV loops
		526	support overloading, however, as well as all functions that use perl to
		527	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		528	example).
		529
		530	=item $cv->croak ($error)
		531
		532	Similar to send, but causes all call's to C<< ->recv >> to invoke
		533	C<Carp::croak> with the given error message/object/scalar.
		534
		535	This can be used to signal any errors to the condition variable
		536	user/consumer.
		537
		538	=item $cv->begin ([group callback])
		539
328	=item $cv->wait	540	=item $cv->end
329		541
330	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	542	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		543
		544	These two methods can be used to combine many transactions/events into
		545	one. For example, a function that pings many hosts in parallel might want
		546	to use a condition variable for the whole process.
		547
		548	Every call to C<< ->begin >> will increment a counter, and every call to
		549	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		550	>>, the (last) callback passed to C<begin> will be executed. That callback
		551	is I<supposed> to call C<< ->send >>, but that is not required. If no
		552	callback was set, C<send> will be called without any arguments.
		553
		554	Let's clarify this with the ping example:
		555
		556	my $cv = AnyEvent->condvar;
		557
		558	my %result;
		559	$cv->begin (sub { $cv->send (\%result) });
		560
		561	for my $host (@list_of_hosts) {
		562	$cv->begin;
		563	ping_host_then_call_callback $host, sub {
		564	$result{$host} = ...;
		565	$cv->end;
		566	};
		567	}
		568
		569	$cv->end;
		570
		571	This code fragment supposedly pings a number of hosts and calls
		572	C<send> after results for all then have have been gathered - in any
		573	order. To achieve this, the code issues a call to C<begin> when it starts
		574	each ping request and calls C<end> when it has received some result for
		575	it. Since C<begin> and C<end> only maintain a counter, the order in which
		576	results arrive is not relevant.
		577
		578	There is an additional bracketing call to C<begin> and C<end> outside the
		579	loop, which serves two important purposes: first, it sets the callback
		580	to be called once the counter reaches C<0>, and second, it ensures that
		581	C<send> is called even when C<no> hosts are being pinged (the loop
		582	doesn't execute once).
		583
		584	This is the general pattern when you "fan out" into multiple subrequests:
		585	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		586	is called at least once, and then, for each subrequest you start, call
		587	C<begin> and for each subrequest you finish, call C<end>.
		588
		589	=back
		590
		591	=head3 METHODS FOR CONSUMERS
		592
		593	These methods should only be used by the consuming side, i.e. the
		594	code awaits the condition.
		595
		596	=over 4
		597
		598	=item $cv->recv
		599
		600	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	601	>> methods have been called on c<$cv>, while servicing other watchers
		602	normally.
332		603
333	You can only wait once on a condition - additional calls will return	604	You can only wait once on a condition - additional calls are valid but
334	immediately.	605	will return immediately.
		606
		607	If an error condition has been set by calling C<< ->croak >>, then this
		608	function will call C<croak>.
		609
		610	In list context, all parameters passed to C<send> will be returned,
		611	in scalar context only the first one will be returned.
335		612
336	Not all event models support a blocking wait - some die in that case	613	Not all event models support a blocking wait - some die in that case
337	(programs might want to do that to stay interactive), so I<if you are	614	(programs might want to do that to stay interactive), so I<if you are
338	using this from a module, never require a blocking wait>, but let the	615	using this from a module, never require a blocking wait>, but let the
339	caller decide whether the call will block or not (for example, by coupling	616	caller decide whether the call will block or not (for example, by coupling
340	condition variables with some kind of request results and supporting	617	condition variables with some kind of request results and supporting
341	callbacks so the caller knows that getting the result will not block,	618	callbacks so the caller knows that getting the result will not block,
342	while still suppporting blocking waits if the caller so desires).	619	while still supporting blocking waits if the caller so desires).
343		620
344	Another reason I<never> to C<< ->wait >> in a module is that you cannot	621	Another reason I<never> to C<< ->recv >> in a module is that you cannot
345	sensibly have two C<< ->wait >>'s in parallel, as that would require	622	sensibly have two C<< ->recv >>'s in parallel, as that would require
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	623	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	624	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		625
351	=item $cv->broadcast	626	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		627	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		628	versions and also integrates coroutines into AnyEvent, making blocking
		629	C<< ->recv >> calls perfectly safe as long as they are done from another
		630	coroutine (one that doesn't run the event loop).
352		631
353	Flag the condition as ready - a running C<< ->wait >> and all further	632	You can ensure that C<< -recv >> never blocks by setting a callback and
354	calls to C<wait> will (eventually) return after this method has been	633	only calling C<< ->recv >> from within that callback (or at a later
355	called. If nobody is waiting the broadcast will be remembered..	634	time). This will work even when the event loop does not support blocking
		635	waits otherwise.
		636
		637	=item $bool = $cv->ready
		638
		639	Returns true when the condition is "true", i.e. whether C<send> or
		640	C<croak> have been called.
		641
		642	=item $cb = $cv->cb ($cb->($cv))
		643
		644	This is a mutator function that returns the callback set and optionally
		645	replaces it before doing so.
		646
		647	The callback will be called when the condition becomes "true", i.e. when
		648	C<send> or C<croak> are called, with the only argument being the condition
		649	variable itself. Calling C<recv> inside the callback or at any later time
		650	is guaranteed not to block.
356		651
357	=back	652	=back
358
359	Example:
360
361	# wait till the result is ready
362	my $result_ready = AnyEvent->condvar;
363
364	# do something such as adding a timer
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372
373	# this "blocks" (while handling events) till the watcher
374	# calls broadcast
375	$result_ready->wait;
376		653
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		655
379	=over 4	656	=over 4
380		657
…		…
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	663	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	664	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388		665
389	The known classes so far are:	666	The known classes so far are:
390		667
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	668	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.	669	AnyEvent::Impl::Event based on Event, second best choice.
		670	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.	671	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.	672	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	673	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	674	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.	675	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401		676
…		…
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	689	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	if necessary. You should only call this function right before you would	690	if necessary. You should only call this function right before you would
416	have created an AnyEvent watcher anyway, that is, as late as possible at	691	have created an AnyEvent watcher anyway, that is, as late as possible at
417	runtime.	692	runtime.
418		693
		694	=item $guard = AnyEvent::post_detect { BLOCK }
		695
		696	Arranges for the code block to be executed as soon as the event model is
		697	autodetected (or immediately if this has already happened).
		698
		699	If called in scalar or list context, then it creates and returns an object
		700	that automatically removes the callback again when it is destroyed. See
		701	L<Coro::BDB> for a case where this is useful.
		702
		703	=item @AnyEvent::post_detect
		704
		705	If there are any code references in this array (you can C<push> to it
		706	before or after loading AnyEvent), then they will called directly after
		707	the event loop has been chosen.
		708
		709	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		710	if it contains a true value then the event loop has already been detected,
		711	and the array will be ignored.
		712
		713	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		714
419	=back	715	=back
420		716
421	=head1 WHAT TO DO IN A MODULE	717	=head1 WHAT TO DO IN A MODULE
422		718
423	As a module author, you should C<use AnyEvent> and call AnyEvent methods	719	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
426	Be careful when you create watchers in the module body - AnyEvent will	722	Be careful when you create watchers in the module body - AnyEvent will
427	decide which event module to use as soon as the first method is called, so	723	decide which event module to use as soon as the first method is called, so
428	by calling AnyEvent in your module body you force the user of your module	724	by calling AnyEvent in your module body you force the user of your module
429	to load the event module first.	725	to load the event module first.
430		726
431	Never call C<< ->wait >> on a condition variable unless you I<know> that	727	Never call C<< ->recv >> on a condition variable unless you I<know> that
432	the C<< ->broadcast >> method has been called on it already. This is	728	the C<< ->send >> method has been called on it already. This is
433	because it will stall the whole program, and the whole point of using	729	because it will stall the whole program, and the whole point of using
434	events is to stay interactive.	730	events is to stay interactive.
435		731
436	It is fine, however, to call C<< ->wait >> when the user of your module	732	It is fine, however, to call C<< ->recv >> when the user of your module
437	requests it (i.e. if you create a http request object ad have a method	733	requests it (i.e. if you create a http request object ad have a method
438	called C<results> that returns the results, it should call C<< ->wait >>	734	called C<results> that returns the results, it should call C<< ->recv >>
439	freely, as the user of your module knows what she is doing. always).	735	freely, as the user of your module knows what she is doing. always).
440		736
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	737	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		738
443	There will always be a single main program - the only place that should	739	There will always be a single main program - the only place that should
…		…
445		741
446	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	742	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
447	do anything special (it does not need to be event-based) and let AnyEvent	743	do anything special (it does not need to be event-based) and let AnyEvent
448	decide which implementation to chose if some module relies on it.	744	decide which implementation to chose if some module relies on it.
449		745
450	If the main program relies on a specific event model. For example, in	746	If the main program relies on a specific event model - for example, in
451	Gtk2 programs you have to rely on the Glib module. You should load the	747	Gtk2 programs you have to rely on the Glib module - you should load the
452	event module before loading AnyEvent or any module that uses it: generally	748	event module before loading AnyEvent or any module that uses it: generally
453	speaking, you should load it as early as possible. The reason is that	749	speaking, you should load it as early as possible. The reason is that
454	modules might create watchers when they are loaded, and AnyEvent will	750	modules might create watchers when they are loaded, and AnyEvent will
455	decide on the event model to use as soon as it creates watchers, and it	751	decide on the event model to use as soon as it creates watchers, and it
456	might chose the wrong one unless you load the correct one yourself.	752	might chose the wrong one unless you load the correct one yourself.
457		753
458	You can chose to use a rather inefficient pure-perl implementation by	754	You can chose to use a pure-perl implementation by loading the
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	behaviour everywhere, but letting AnyEvent chose is generally better.	756	everywhere, but letting AnyEvent chose the model is generally better.
		757
		758	=head2 MAINLOOP EMULATION
		759
		760	Sometimes (often for short test scripts, or even standalone programs who
		761	only want to use AnyEvent), you do not want to run a specific event loop.
		762
		763	In that case, you can use a condition variable like this:
		764
		765	AnyEvent->condvar->recv;
		766
		767	This has the effect of entering the event loop and looping forever.
		768
		769	Note that usually your program has some exit condition, in which case
		770	it is better to use the "traditional" approach of storing a condition
		771	variable somewhere, waiting for it, and sending it when the program should
		772	exit cleanly.
		773
461		774
462	=head1 OTHER MODULES	775	=head1 OTHER MODULES
463		776
464	The following is a non-exhaustive list of additional modules that use	777	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
471	=item L<AnyEvent::Util>	784	=item L<AnyEvent::Util>
472		785
473	Contains various utility functions that replace often-used but blocking	786	Contains various utility functions that replace often-used but blocking
474	functions such as C<inet_aton> by event-/callback-based versions.	787	functions such as C<inet_aton> by event-/callback-based versions.
475		788
		789	=item L<AnyEvent::Socket>
		790
		791	Provides various utility functions for (internet protocol) sockets,
		792	addresses and name resolution. Also functions to create non-blocking tcp
		793	connections or tcp servers, with IPv6 and SRV record support and more.
		794
476	=item L<AnyEvent::Handle>	795	=item L<AnyEvent::Handle>
477		796
478	Provide read and write buffers and manages watchers for reads and writes.	797	Provide read and write buffers, manages watchers for reads and writes,
		798	supports raw and formatted I/O, I/O queued and fully transparent and
		799	non-blocking SSL/TLS.
479		800
480	=item L<AnyEvent::Socket>	801	=item L<AnyEvent::DNS>
481		802
482	Provides a means to do non-blocking connects, accepts etc.	803	Provides rich asynchronous DNS resolver capabilities.
		804
		805	=item L<AnyEvent::HTTP>
		806
		807	A simple-to-use HTTP library that is capable of making a lot of concurrent
		808	HTTP requests.
483		809
484	=item L<AnyEvent::HTTPD>	810	=item L<AnyEvent::HTTPD>
485		811
486	Provides a simple web application server framework.	812	Provides a simple web application server framework.
487		813
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492
493	=item L<AnyEvent::FastPing>	814	=item L<AnyEvent::FastPing>
494		815
495	The fastest ping in the west.	816	The fastest ping in the west.
496		817
		818	=item L<AnyEvent::DBI>
		819
		820	Executes L<DBI> requests asynchronously in a proxy process.
		821
		822	=item L<AnyEvent::AIO>
		823
		824	Truly asynchronous I/O, should be in the toolbox of every event
		825	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		826	together.
		827
		828	=item L<AnyEvent::BDB>
		829
		830	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		831	L<BDB> and AnyEvent together.
		832
		833	=item L<AnyEvent::GPSD>
		834
		835	A non-blocking interface to gpsd, a daemon delivering GPS information.
		836
		837	=item L<AnyEvent::IGS>
		838
		839	A non-blocking interface to the Internet Go Server protocol (used by
		840	L<App::IGS>).
		841
497	=item L<Net::IRC3>	842	=item L<AnyEvent::IRC>
498		843
499	AnyEvent based IRC client module family.	844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
500		845
501	=item L<Net::XMPP2>	846	=item L<Net::XMPP2>
502		847
503	AnyEvent based XMPP (Jabber protocol) module family.	848	AnyEvent based XMPP (Jabber protocol) module family.
504		849
…		…
511		856
512	High level API for event-based execution flow control.	857	High level API for event-based execution flow control.
513		858
514	=item L<Coro>	859	=item L<Coro>
515		860
516	Has special support for AnyEvent.	861	Has special support for AnyEvent via L<Coro::AnyEvent>.
517		862
518	=item L<IO::Lambda>	863	=item L<IO::Lambda>
519		864
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521		866
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531
532	=back	867	=back
533		868
534	=cut	869	=cut
535		870
536	package AnyEvent;	871	package AnyEvent;
537		872
538	no warnings;	873	no warnings;
539	use strict;	874	use strict qw(vars subs);
540		875
541	use Carp;	876	use Carp;
542		877
543	our $VERSION = '3.3';	878	our $VERSION = 4.35;
544	our $MODEL;	879	our $MODEL;
545		880
546	our $AUTOLOAD;	881	our $AUTOLOAD;
547	our @ISA;	882	our @ISA;
548		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		894
551	our @REGISTRY;	895	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		896
		897	{
		898	my $idx;
		899	$PROTOCOL{$_} = ++$idx
		900	for reverse split /\s*,\s*/,
		901	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		902	}
552		903
553	my @models = (	904	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],
559	[Tk:: => AnyEvent::Impl::Tk::],
560	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
		909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
567	);	918	);
568		919
569	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		921
		922	our @post_detect;
		923
		924	sub post_detect(&) {
		925	my ($cb) = @_;
		926
		927	if ($MODEL) {
		928	$cb->();
		929
		930	1
		931	} else {
		932	push @post_detect, $cb;
		933
		934	defined wantarray
		935	? bless \$cb, "AnyEvent::Util::PostDetect"
		936	: ()
		937	}
		938	}
		939
		940	sub AnyEvent::Util::PostDetect::DESTROY {
		941	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		942	}
570		943
571	sub detect() {	944	sub detect() {
572	unless ($MODEL) {	945	unless ($MODEL) {
573	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
574		948
575	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
577	if (eval "require $model") {	951	if (eval "require $model") {
578	$MODEL = $model;	952	$MODEL = $model;
…		…
608	last;	982	last;
609	}	983	}
610	}	984	}
611		985
612	$MODEL	986	$MODEL
613	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
614	}	988	}
615	}	989	}
616		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
617	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		996
		997	(shift @post_detect)->() while @post_detect;
619	}	998	}
620		999
621	$MODEL	1000	$MODEL
622	}	1001	}
623		1002
…		…
631		1010
632	my $class = shift;	1011	my $class = shift;
633	$class->$func (@_);	1012	$class->$func (@_);
634	}	1013	}
635		1014
		1015	# utility function to dup a filehandle. this is used by many backends
		1016	# to support binding more than one watcher per filehandle (they usually
		1017	# allow only one watcher per fd, so we dup it to get a different one).
		1018	sub _dupfh($$$$) {
		1019	my ($poll, $fh, $r, $w) = @_;
		1020
		1021	# cygwin requires the fh mode to be matching, unix doesn't
		1022	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1023	: $poll eq "w" ? ($w, ">")
		1024	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1025
		1026	open my $fh2, "$mode&" . fileno $fh
		1027	or die "cannot dup() filehandle: $!";
		1028
		1029	# we assume CLOEXEC is already set by perl in all important cases
		1030
		1031	($fh2, $rw)
		1032	}
		1033
636	package AnyEvent::Base;	1034	package AnyEvent::Base;
637		1035
		1036	# default implementation for now and time
		1037
		1038	BEGIN {
		1039	if (eval "use Time::HiRes (); time (); 1") {
		1040	*_time = \&Time::HiRes::time;
		1041	# if (eval "use POSIX (); (POSIX::times())...
		1042	} else {
		1043	*_time = sub { time }; # epic fail
		1044	}
		1045	}
		1046
		1047	sub time { _time }
		1048	sub now { _time }
		1049
638	# default implementation for ->condvar, ->wait, ->broadcast	1050	# default implementation for ->condvar
639		1051
640	sub condvar {	1052	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	1054	}
651		1055
652	# default implementation for ->signal	1056	# default implementation for ->signal
653		1057
654	our %SIG_CB;	1058	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1059
		1060	sub _signal_exec {
		1061	sysread $SIGPIPE_R, my $dummy, 4;
		1062
		1063	while (%SIG_EV) {
		1064	for (keys %SIG_EV) {
		1065	delete $SIG_EV{$_};
		1066	$_->() for values %{ $SIG_CB{$_} || {} };
		1067	}
		1068	}
		1069	}
655		1070
656	sub signal {	1071	sub signal {
657	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
658		1073
		1074	unless ($SIGPIPE_R) {
		1075	require Fcntl;
		1076
		1077	if (AnyEvent::WIN32) {
		1078	require AnyEvent::Util;
		1079
		1080	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1081	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1082	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1083	} else {
		1084	pipe $SIGPIPE_R, $SIGPIPE_W;
		1085	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1086	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1087	}
		1088
		1089	$SIGPIPE_R
		1090	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1091
		1092	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1093	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094
		1095	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1096	}
		1097
659	my $signal = uc $arg{signal}	1098	my $signal = uc $arg{signal}
660	or Carp::croak "required option 'signal' is missing";	1099	or Carp::croak "required option 'signal' is missing";
661		1100
662	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1101	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
663	$SIG{$signal} ||= sub {	1102	$SIG{$signal} ||= sub {
664	$_->() for values %{ $SIG_CB{$signal} || {} };	1103	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1104	undef $SIG_EV{$signal};
665	};	1105	};
666		1106
667	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1107	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
668	}	1108	}
669		1109
670	sub AnyEvent::Base::Signal::DESTROY {	1110	sub AnyEvent::Base::Signal::DESTROY {
671	my ($signal, $cb) = @{$_[0]};	1111	my ($signal, $cb) = @{$_[0]};
672		1112
673	delete $SIG_CB{$signal}{$cb};	1113	delete $SIG_CB{$signal}{$cb};
674		1114
675	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1115	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
676	}	1116	}
677		1117
678	# default implementation for ->child	1118	# default implementation for ->child
679		1119
680	our %PID_CB;	1120	our %PID_CB;
…		…
707	or Carp::croak "required option 'pid' is missing";	1147	or Carp::croak "required option 'pid' is missing";
708		1148
709	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1149	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
710		1150
711	unless ($WNOHANG) {	1151	unless ($WNOHANG) {
712	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1152	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
713	}	1153	}
714		1154
715	unless ($CHLD_W) {	1155	unless ($CHLD_W) {
716	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1156	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717	# child could be a zombie already, so make at least one round	1157	# child could be a zombie already, so make at least one round
…		…
727	delete $PID_CB{$pid}{$cb};	1167	delete $PID_CB{$pid}{$cb};
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1168	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		1169
730	undef $CHLD_W unless keys %PID_CB;	1170	undef $CHLD_W unless keys %PID_CB;
731	}	1171	}
		1172
		1173	package AnyEvent::CondVar;
		1174
		1175	our @ISA = AnyEvent::CondVar::Base::;
		1176
		1177	package AnyEvent::CondVar::Base;
		1178
		1179	use overload
		1180	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1181	fallback => 1;
		1182
		1183	sub _send {
		1184	# nop
		1185	}
		1186
		1187	sub send {
		1188	my $cv = shift;
		1189	$cv->{_ae_sent} = [@_];
		1190	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1191	$cv->_send;
		1192	}
		1193
		1194	sub croak {
		1195	$_[0]{_ae_croak} = $_[1];
		1196	$_[0]->send;
		1197	}
		1198
		1199	sub ready {
		1200	$_[0]{_ae_sent}
		1201	}
		1202
		1203	sub _wait {
		1204	AnyEvent->one_event while !$_[0]{_ae_sent};
		1205	}
		1206
		1207	sub recv {
		1208	$_[0]->_wait;
		1209
		1210	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1211	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1212	}
		1213
		1214	sub cb {
		1215	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1216	$_[0]{_ae_cb}
		1217	}
		1218
		1219	sub begin {
		1220	++$_[0]{_ae_counter};
		1221	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1222	}
		1223
		1224	sub end {
		1225	return if --$_[0]{_ae_counter};
		1226	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1227	}
		1228
		1229	# undocumented/compatibility with pre-3.4
		1230	*broadcast = \&send;
		1231	*wait = \&_wait;
		1232
		1233	=head1 ERROR AND EXCEPTION HANDLING
		1234
		1235	In general, AnyEvent does not do any error handling - it relies on the
		1236	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1237	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1238	checking of all AnyEvent methods, however, which is highly useful during
		1239	development.
		1240
		1241	As for exception handling (i.e. runtime errors and exceptions thrown while
		1242	executing a callback), this is not only highly event-loop specific, but
		1243	also not in any way wrapped by this module, as this is the job of the main
		1244	program.
		1245
		1246	The pure perl event loop simply re-throws the exception (usually
		1247	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1248	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1249	so on.
		1250
		1251	=head1 ENVIRONMENT VARIABLES
		1252
		1253	The following environment variables are used by this module or its
		1254	submodules:
		1255
		1256	=over 4
		1257
		1258	=item C<PERL_ANYEVENT_VERBOSE>
		1259
		1260	By default, AnyEvent will be completely silent except in fatal
		1261	conditions. You can set this environment variable to make AnyEvent more
		1262	talkative.
		1263
		1264	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1265	conditions, such as not being able to load the event model specified by
		1266	C<PERL_ANYEVENT_MODEL>.
		1267
		1268	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1269	model it chooses.
		1270
		1271	=item C<PERL_ANYEVENT_STRICT>
		1272
		1273	AnyEvent does not do much argument checking by default, as thorough
		1274	argument checking is very costly. Setting this variable to a true value
		1275	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1276	check the arguments passed to most method calls. If it finds any problems
		1277	it will croak.
		1278
		1279	In other words, enables "strict" mode.
		1280
		1281	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1282	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1283	developing programs can be very useful, however.
		1284
		1285	=item C<PERL_ANYEVENT_MODEL>
		1286
		1287	This can be used to specify the event model to be used by AnyEvent, before
		1288	auto detection and -probing kicks in. It must be a string consisting
		1289	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1290	and the resulting module name is loaded and if the load was successful,
		1291	used as event model. If it fails to load AnyEvent will proceed with
		1292	auto detection and -probing.
		1293
		1294	This functionality might change in future versions.
		1295
		1296	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1297	could start your program like this:
		1298
		1299	PERL_ANYEVENT_MODEL=Perl perl ...
		1300
		1301	=item C<PERL_ANYEVENT_PROTOCOLS>
		1302
		1303	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1304	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1305	of auto probing).
		1306
		1307	Must be set to a comma-separated list of protocols or address families,
		1308	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1309	used, and preference will be given to protocols mentioned earlier in the
		1310	list.
		1311
		1312	This variable can effectively be used for denial-of-service attacks
		1313	against local programs (e.g. when setuid), although the impact is likely
		1314	small, as the program has to handle conenction and other failures anyways.
		1315
		1316	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1317	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1318	- only support IPv4, never try to resolve or contact IPv6
		1319	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1320	IPv6, but prefer IPv6 over IPv4.
		1321
		1322	=item C<PERL_ANYEVENT_EDNS0>
		1323
		1324	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1325	for DNS. This extension is generally useful to reduce DNS traffic, but
		1326	some (broken) firewalls drop such DNS packets, which is why it is off by
		1327	default.
		1328
		1329	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1330	EDNS0 in its DNS requests.
		1331
		1332	=item C<PERL_ANYEVENT_MAX_FORKS>
		1333
		1334	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1335	will create in parallel.
		1336
		1337	=back
732		1338
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1339	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1340
735	This is an advanced topic that you do not normally need to use AnyEvent in	1341	This is an advanced topic that you do not normally need to use AnyEvent in
736	a module. This section is only of use to event loop authors who want to	1342	a module. This section is only of use to event loop authors who want to
…		…
770		1376
771	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1377	I<rxvt-unicode> also cheats a bit by not providing blocking access to
772	condition variables: code blocking while waiting for a condition will	1378	condition variables: code blocking while waiting for a condition will
773	C<die>. This still works with most modules/usages, and blocking calls must	1379	C<die>. This still works with most modules/usages, and blocking calls must
774	not be done in an interactive application, so it makes sense.	1380	not be done in an interactive application, so it makes sense.
775
776	=head1 ENVIRONMENT VARIABLES
777
778	The following environment variables are used by this module:
779
780	=over 4
781
782	=item C<PERL_ANYEVENT_VERBOSE>
783
784	By default, AnyEvent will be completely silent except in fatal
785	conditions. You can set this environment variable to make AnyEvent more
786	talkative.
787
788	When set to C<1> or higher, causes AnyEvent to warn about unexpected
789	conditions, such as not being able to load the event model specified by
790	C<PERL_ANYEVENT_MODEL>.
791
792	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
793	model it chooses.
794
795	=item C<PERL_ANYEVENT_MODEL>
796
797	This can be used to specify the event model to be used by AnyEvent, before
798	autodetection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	and the resulting module name is loaded and if the load was successful,
801	used as event model. If it fails to load AnyEvent will proceed with
802	autodetection and -probing.
803
804	This functionality might change in future versions.
805
806	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
807	could start your program like this:
808
809	PERL_ANYEVENT_MODEL=Perl perl ...
810
811	=back
812		1381
813	=head1 EXAMPLE PROGRAM	1382	=head1 EXAMPLE PROGRAM
814		1383
815	The following program uses an I/O watcher to read data from STDIN, a timer	1384	The following program uses an I/O watcher to read data from STDIN, a timer
816	to display a message once per second, and a condition variable to quit the	1385	to display a message once per second, and a condition variable to quit the
…		…
825	poll => 'r',	1394	poll => 'r',
826	cb => sub {	1395	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1396	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1397	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1398	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1399	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1400	},
832	);	1401	);
833		1402
834	my $time_watcher; # can only be used once	1403	my $time_watcher; # can only be used once
835		1404
…		…
840	});	1409	});
841	}	1410	}
842		1411
843	new_timer; # create first timer	1412	new_timer; # create first timer
844		1413
845	$cv->wait; # wait until user enters /^q/i	1414	$cv->recv; # wait until user enters /^q/i
846		1415
847	=head1 REAL-WORLD EXAMPLE	1416	=head1 REAL-WORLD EXAMPLE
848		1417
849	Consider the L<Net::FCP> module. It features (among others) the following	1418	Consider the L<Net::FCP> module. It features (among others) the following
850	API calls, which are to freenet what HTTP GET requests are to http:	1419	API calls, which are to freenet what HTTP GET requests are to http:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1469	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1470	or die "connection or write error";
902	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1471	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
903		1472
904	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1473	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
905	result and signals any possible waiters that the request ahs finished:	1474	result and signals any possible waiters that the request has finished:
906		1475
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1476	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1477
909	if (end-of-file or data complete) {	1478	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1479	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1480	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1481	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1482	}
914		1483
915	The C<result> method, finally, just waits for the finished signal (if the	1484	The C<result> method, finally, just waits for the finished signal (if the
916	request was already finished, it doesn't wait, of course, and returns the	1485	request was already finished, it doesn't wait, of course, and returns the
917	data:	1486	data:
918		1487
919	$txn->{finished}->wait;	1488	$txn->{finished}->recv;
920	return $txn->{result};	1489	return $txn->{result};
921		1490
922	The actual code goes further and collects all errors (C<die>s, exceptions)	1491	The actual code goes further and collects all errors (C<die>s, exceptions)
923	that occured during request processing. The C<result> method detects	1492	that occurred during request processing. The C<result> method detects
924	whether an exception as thrown (it is stored inside the $txn object)	1493	whether an exception as thrown (it is stored inside the $txn object)
925	and just throws the exception, which means connection errors and other	1494	and just throws the exception, which means connection errors and other
926	problems get reported tot he code that tries to use the result, not in a	1495	problems get reported tot he code that tries to use the result, not in a
927	random callback.	1496	random callback.
928		1497
…		…
959		1528
960	my $quit = AnyEvent->condvar;	1529	my $quit = AnyEvent->condvar;
961		1530
962	$fcp->txn_client_get ($url)->cb (sub {	1531	$fcp->txn_client_get ($url)->cb (sub {
963	...	1532	...
964	$quit->broadcast;	1533	$quit->send;
965	});	1534	});
966		1535
967	$quit->wait;	1536	$quit->recv;
968		1537
969		1538
970	=head1 BENCHMARKS	1539	=head1 BENCHMARKS
971		1540
972	To give you an idea of the performance and overheads that AnyEvent adds	1541	To give you an idea of the performance and overheads that AnyEvent adds
…		…
974	of various event loops I prepared some benchmarks.	1543	of various event loops I prepared some benchmarks.
975		1544
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1545	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1546
978	Here is a benchmark of various supported event models used natively and	1547	Here is a benchmark of various supported event models used natively and
979	through anyevent. The benchmark creates a lot of timers (with a zero	1548	through AnyEvent. The benchmark creates a lot of timers (with a zero
980	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1549	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981	which it is), lets them fire exactly once and destroys them again.	1550	which it is), lets them fire exactly once and destroys them again.
982		1551
983	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1552	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
984	distribution.	1553	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1570	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1571	and memory usage is not included in the figures.
1003		1572
1004	I<invoke> is the time, in microseconds, used to invoke a simple	1573	I<invoke> is the time, in microseconds, used to invoke a simple
1005	callback. The callback simply counts down a Perl variable and after it was	1574	callback. The callback simply counts down a Perl variable and after it was
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1575	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1576	signal the end of this phase.
1008		1577
1009	I<destroy> is the time, in microseconds, that it takes to destroy a single	1578	I<destroy> is the time, in microseconds, that it takes to destroy a single
1010	watcher.	1579	watcher.
1011		1580
1012	=head3 Results	1581	=head3 Results
1013		1582
1014	name watchers bytes create invoke destroy comment	1583	name watchers bytes create invoke destroy comment
1015	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1584	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1016	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1585	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1017	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1586	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1018	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1587	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1019	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1588	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1020	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1589	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1021	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1590	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1022	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1591	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1023	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1592	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1024	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1593	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1025		1594
1026	=head3 Discussion	1595	=head3 Discussion
1027		1596
1028	The benchmark does I<not> measure scalability of the event loop very	1597	The benchmark does I<not> measure scalability of the event loop very
1029	well. For example, a select-based event loop (such as the pure perl one)	1598	well. For example, a select-based event loop (such as the pure perl one)
…		…
1107		1676
1108	=back	1677	=back
1109		1678
1110	=head2 BENCHMARKING THE LARGE SERVER CASE	1679	=head2 BENCHMARKING THE LARGE SERVER CASE
1111		1680
1112	This benchmark atcually benchmarks the event loop itself. It works by	1681	This benchmark actually benchmarks the event loop itself. It works by
1113	creating a number of "servers": each server consists of a socketpair, a	1682	creating a number of "servers": each server consists of a socket pair, a
1114	timeout watcher that gets reset on activity (but never fires), and an I/O	1683	timeout watcher that gets reset on activity (but never fires), and an I/O
1115	watcher waiting for input on one side of the socket. Each time the socket	1684	watcher waiting for input on one side of the socket. Each time the socket
1116	watcher reads a byte it will write that byte to a random other "server".	1685	watcher reads a byte it will write that byte to a random other "server".
1117		1686
1118	The effect is that there will be a lot of I/O watchers, only part of which	1687	The effect is that there will be a lot of I/O watchers, only part of which
1119	are active at any one point (so there is a constant number of active	1688	are active at any one point (so there is a constant number of active
1120	fds for each loop iterstaion, but which fds these are is random). The	1689	fds for each loop iteration, but which fds these are is random). The
1121	timeout is reset each time something is read because that reflects how	1690	timeout is reset each time something is read because that reflects how
1122	most timeouts work (and puts extra pressure on the event loops).	1691	most timeouts work (and puts extra pressure on the event loops).
1123		1692
1124	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1693	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1125	(1%) are active. This mirrors the activity of large servers with many	1694	(1%) are active. This mirrors the activity of large servers with many
1126	connections, most of which are idle at any one point in time.	1695	connections, most of which are idle at any one point in time.
1127		1696
1128	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1697	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1129	distribution.	1698	distribution.
…		…
1131	=head3 Explanation of the columns	1700	=head3 Explanation of the columns
1132		1701
1133	I<sockets> is the number of sockets, and twice the number of "servers" (as	1702	I<sockets> is the number of sockets, and twice the number of "servers" (as
1134	each server has a read and write socket end).	1703	each server has a read and write socket end).
1135		1704
1136	I<create> is the time it takes to create a socketpair (which is	1705	I<create> is the time it takes to create a socket pair (which is
1137	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1706	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1138		1707
1139	I<request>, the most important value, is the time it takes to handle a	1708	I<request>, the most important value, is the time it takes to handle a
1140	single "request", that is, reading the token from the pipe and forwarding	1709	single "request", that is, reading the token from the pipe and forwarding
1141	it to another server. This includes deleting the old timeout and creating	1710	it to another server. This includes deleting the old timeout and creating
…		…
1214	speed most when you have lots of watchers, not when you only have a few of	1783	speed most when you have lots of watchers, not when you only have a few of
1215	them).	1784	them).
1216		1785
1217	EV is again fastest.	1786	EV is again fastest.
1218		1787
1219	Perl again comes second. It is noticably faster than the C-based event	1788	Perl again comes second. It is noticeably faster than the C-based event
1220	loops Event and Glib, although the difference is too small to really	1789	loops Event and Glib, although the difference is too small to really
1221	matter.	1790	matter.
1222		1791
1223	POE also performs much better in this case, but is is still far behind the	1792	POE also performs much better in this case, but is is still far behind the
1224	others.	1793	others.
…		…
1231	watchers, as the management overhead dominates.	1800	watchers, as the management overhead dominates.
1232		1801
1233	=back	1802	=back
1234		1803
1235		1804
		1805	=head1 SIGNALS
		1806
		1807	AnyEvent currently installs handlers for these signals:
		1808
		1809	=over 4
		1810
		1811	=item SIGCHLD
		1812
		1813	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1814	emulation for event loops that do not support them natively. Also, some
		1815	event loops install a similar handler.
		1816
		1817	=item SIGPIPE
		1818
		1819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1820	when AnyEvent gets loaded.
		1821
		1822	The rationale for this is that AnyEvent users usually do not really depend
		1823	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1824	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1825	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1826	some random socket.
		1827
		1828	The rationale for installing a no-op handler as opposed to ignoring it is
		1829	that this way, the handler will be restored to defaults on exec.
		1830
		1831	Feel free to install your own handler, or reset it to defaults.
		1832
		1833	=back
		1834
		1835	=cut
		1836
		1837	$SIG{PIPE} = sub { }
		1838	unless defined $SIG{PIPE};
		1839
		1840
1236	=head1 FORK	1841	=head1 FORK
1237		1842
1238	Most event libraries are not fork-safe. The ones who are usually are	1843	Most event libraries are not fork-safe. The ones who are usually are
1239	because they are so inefficient. Only L<EV> is fully fork-aware.	1844	because they rely on inefficient but fork-safe C<select> or C<poll>
		1845	calls. Only L<EV> is fully fork-aware.
1240		1846
1241	If you have to fork, you must either do so I<before> creating your first	1847	If you have to fork, you must either do so I<before> creating your first
1242	watcher OR you must not use AnyEvent at all in the child.	1848	watcher OR you must not use AnyEvent at all in the child.
1243		1849
1244		1850
…		…
1252	specified in the variable.	1858	specified in the variable.
1253		1859
1254	You can make AnyEvent completely ignore this variable by deleting it	1860	You can make AnyEvent completely ignore this variable by deleting it
1255	before the first watcher gets created, e.g. with a C<BEGIN> block:	1861	before the first watcher gets created, e.g. with a C<BEGIN> block:
1256		1862
1257	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1863	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1258		1864
1259	use AnyEvent;	1865	use AnyEvent;
		1866
		1867	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1868	be used to probe what backend is used and gain other information (which is
		1869	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1870	$ENV{PERL_ANYEGENT_STRICT}.
		1871
		1872
		1873	=head1 BUGS
		1874
		1875	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1876	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1877	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1878	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1879	pronounced).
1260		1880
1261		1881
1262	=head1 SEE ALSO	1882	=head1 SEE ALSO
1263		1883
1264	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1884	Utility functions: L<AnyEvent::Util>.
1265	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1885
		1886	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1266	L<Event::Lib>, L<Qt>, L<POE>.	1887	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1267		1888
1268	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1889	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1269	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1890	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1270	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1891	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1271	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1892	L<AnyEvent::Impl::POE>.
1272		1893
		1894	Non-blocking file handles, sockets, TCP clients and
		1895	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1896
		1897	Asynchronous DNS: L<AnyEvent::DNS>.
		1898
		1899	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1900
1273	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1901	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1274		1902
1275		1903
1276	=head1 AUTHOR	1904	=head1 AUTHOR
1277		1905
1278	Marc Lehmann <schmorp@schmorp.de>	1906	Marc Lehmann <schmorp@schmorp.de>
1279	http://home.schmorp.de/	1907	http://home.schmorp.de/
1280		1908
1281	=cut	1909	=cut
1282		1910
1283	1	1911	1
1284		1912

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