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Revision 1.202 by root, Wed Apr 1 15:29:00 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	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		92
91	=head1 DESCRIPTION	93	=head1 DESCRIPTION
92		94
93	L<AnyEvent> provides an identical interface to multiple event loops. This	95	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	96	allows module authors to utilise an event loop without forcing module
…		…
98	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>
99	module.	101	module.
100		102
101	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
102	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
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
104	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>,
105	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
106	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
107	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
108	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
…		…
122	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
123	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
124		126
125	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
126	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
127	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
128		130
129	=head1 WATCHERS	131	=head1 WATCHERS
130		132
131	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
132	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
133	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
134		136
135	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
136	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
137	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
138	is in control).	140	is in control).
139		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
140	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
141	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
142	to it).	150	to it).
143		151
144	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.
…		…
146	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
147	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.
148		156
149	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
150		158
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
153	undef $w;	161	undef $w;
154	});	162	});
155		163
156	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,
157	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
158	declared.	166	declared.
159		167
160	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
161		169
162	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
163	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
164		172
165	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
166	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
167	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
168	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.
169	becomes ready.
170		184
171	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
172	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
173	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
174		188
…		…
178		192
179	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
180	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
181	handles.	195	handles.
182		196
183	Example:
184
185	# 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
186	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
187	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
188	warn "read: $input\n";	202	warn "read: $input\n";
189	undef $w;	203	undef $w;
190	});	204	});
…		…
200		214
201	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
202	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
203	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
204		218
205	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
206	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
207	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.
208		224
209	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.
210		228
211	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
212	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
213	warn "timeout\n";	232	warn "timeout\n";
214	});	233	});
215		234
216	# to cancel the timer:	235	# to cancel the timer:
217	undef $w;	236	undef $w;
218		237
219	Example 2:
220
221	# 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.
222	my $w;
223		239
224	my $cb = sub {
225	# cancel the old timer while creating a new one
226	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
227	};	242	};
228
229	# start the "loop" by creating the first watcher
230	$w = AnyEvent->timer (after => 0.5, cb => $cb);
231		243
232	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
233		245
234	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
235	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
…		…
247	timers.	259	timers.
248		260
249	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	262	AnyEvent API.
251		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
252	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
253		328
254	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
255	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
256	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
257		332
258	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
261		336
262	Multiple signal occurances can be clumped together into one callback	337	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	338	invocation, and callback invocation will be synchronous. Synchronous means
264	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,
265	but it is guarenteed not to interrupt any other callbacks.	340	but it is guaranteed not to interrupt any other callbacks.
266		341
267	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
268	between multiple watchers.	343	between multiple watchers.
269		344
270	This watcher might use C<%SIG>, so programs overwriting those signals	345	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
277	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
278		353
279	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.
280		355
281	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
282	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
283	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
284	signal handler for C<SIGCHLD>. The callback will be called with the pid	359	any trace events (stopped/continued).
285	and exit status (as returned by waitpid), so unlike other watcher types,	360
286	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).
287		369
288	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
289	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
290	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
291		373
…		…
297	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
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
299		381
300	Example: fork a process and wait for it	382	Example: fork a process and wait for it
301		383
302	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
303		385
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
307		387
308	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
309	pid => $pid,	389	pid => $pid,
310	cb => sub {	390	cb => sub {
311	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
313	$done->broadcast;	393	$done->send;
314	},	394	},
315	);	395	);
316		396
317	# do something else, then wait for process exit	397	# do something else, then wait for process exit
318	$done->wait;	398	$done->recv;
319		399
320	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
321		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
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	412	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	413	>> method, usually without arguments. The only argument pair allowed is
324		414
325	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
326	->broadcast >> method has been called.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
327		418
328	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,
329	example, if you write a module that does asynchronous http requests,	432	for example, if you write a module that does asynchronous http requests,
330	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
331	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.
332		436
333	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,
334	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
335	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
336	->broadcast >> the "quit" event.	440	button of your app, which would C<< ->send >> the "quit" event.
337		441
338	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
339	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
340	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
341	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,
342	as this asks for trouble.	446	as this asks for trouble.
343		447
344	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.
345		506
346	=over 4	507	=over 4
347		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
348	=item $cv->wait	540	=item $cv->end
349		541
350	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 $cv->recv
		599
		600	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	601	>> methods have been called on c<$cv>, while servicing other watchers
		602	normally.
352		603
353	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
354	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.
355		612
356	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
357	(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
358	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
359	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
360	condition variables with some kind of request results and supporting	617	condition variables with some kind of request results and supporting
361	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,
362	while still suppporting blocking waits if the caller so desires).	619	while still supporting blocking waits if the caller so desires).
363		620
364	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
365	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
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	623	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	624	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		625
371	=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).
372		631
373	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
374	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
375	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.
376		651
377	=back	652	=back
378
379	Example:
380
381	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;
383
384	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392
393	# this "blocks" (while handling events) till the watcher
394	# calls broadcast
395	$result_ready->wait;
396		653
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		655
399	=over 4	656	=over 4
400		657
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	663	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	664	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		665
409	The known classes so far are:	666	The known classes so far are:
410		667
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	668	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	669	AnyEvent::Impl::Event based on Event, second best choice.
		670	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	671	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	672	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	673	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	674	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	675	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		676
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	689	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	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
436	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
437	runtime.	692	runtime.
438		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
439	=back	715	=back
440		716
441	=head1 WHAT TO DO IN A MODULE	717	=head1 WHAT TO DO IN A MODULE
442		718
443	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
…		…
446	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
447	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
448	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
449	to load the event module first.	725	to load the event module first.
450		726
451	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
452	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
453	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
454	events is to stay interactive.	730	events is to stay interactive.
455		731
456	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
457	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
458	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 >>
459	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).
460		736
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	737	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		738
463	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
…		…
465		741
466	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
467	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
468	decide which implementation to chose if some module relies on it.	744	decide which implementation to chose if some module relies on it.
469		745
470	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
471	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
472	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
473	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
474	modules might create watchers when they are loaded, and AnyEvent will	750	modules might create watchers when they are loaded, and AnyEvent will
475	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
476	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.
477		753
478	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
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	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
		774
		775	=head1 OTHER MODULES
		776
		777	The following is a non-exhaustive list of additional modules that use
		778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		779	in the same program. Some of the modules come with AnyEvent, some are
		780	available via CPAN.
		781
		782	=over 4
		783
		784	=item L<AnyEvent::Util>
		785
		786	Contains various utility functions that replace often-used but blocking
		787	functions such as C<inet_aton> by event-/callback-based versions.
		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
		795	=item L<AnyEvent::Handle>
		796
		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.
		800
		801	=item L<AnyEvent::DNS>
		802
		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.
		809
		810	=item L<AnyEvent::HTTPD>
		811
		812	Provides a simple web application server framework.
		813
		814	=item L<AnyEvent::FastPing>
		815
		816	The fastest ping in the west.
		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
		842	=item L<AnyEvent::IRC>
		843
		844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		845
		846	=item L<Net::XMPP2>
		847
		848	AnyEvent based XMPP (Jabber protocol) module family.
		849
		850	=item L<Net::FCP>
		851
		852	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		853	of AnyEvent.
		854
		855	=item L<Event::ExecFlow>
		856
		857	High level API for event-based execution flow control.
		858
		859	=item L<Coro>
		860
		861	Has special support for AnyEvent via L<Coro::AnyEvent>.
		862
		863	=item L<IO::Lambda>
		864
		865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		866
		867	=back
481		868
482	=cut	869	=cut
483		870
484	package AnyEvent;	871	package AnyEvent;
485		872
486	no warnings;	873	no warnings;
487	use strict;	874	use strict qw(vars subs);
488		875
489	use Carp;	876	use Carp;
490		877
491	our $VERSION = '3.3';	878	our $VERSION = 4.35;
492	our $MODEL;	879	our $MODEL;
493		880
494	our $AUTOLOAD;	881	our $AUTOLOAD;
495	our @ISA;	882	our @ISA;
496		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498		894
499	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	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		902	}
500		903
501	my @models = (	904	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
505	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
506	[Glib:: => AnyEvent::Impl::Glib::],
507	[Tk:: => AnyEvent::Impl::Tk::],
508	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
		909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
515	);	918	);
516		919
517	our %method = map +($_ => 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	}
518		943
519	sub detect() {	944	sub detect() {
520	unless ($MODEL) {	945	unless ($MODEL) {
521	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
522		948
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
524	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	951	if (eval "require $model") {
526	$MODEL = $model;	952	$MODEL = $model;
…		…
556	last;	982	last;
557	}	983	}
558	}	984	}
559		985
560	$MODEL	986	$MODEL
561	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
562	}	988	}
563	}	989	}
564		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
565	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		996
		997	(shift @post_detect)->() while @post_detect;
567	}	998	}
568		999
569	$MODEL	1000	$MODEL
570	}	1001	}
571		1002
…		…
579		1010
580	my $class = shift;	1011	my $class = shift;
581	$class->$func (@_);	1012	$class->$func (@_);
582	}	1013	}
583		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
584	package AnyEvent::Base;	1034	package AnyEvent::Base;
585		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
586	# default implementation for ->condvar, ->wait, ->broadcast	1050	# default implementation for ->condvar
587		1051
588	sub condvar {	1052	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
590	}
591
592	sub AnyEvent::Base::CondVar::broadcast {
593	${$_[0]}++;
594	}
595
596	sub AnyEvent::Base::CondVar::wait {
597	AnyEvent->one_event while !${$_[0]};
598	}	1054	}
599		1055
600	# default implementation for ->signal	1056	# default implementation for ->signal
601		1057
602	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	}
603		1070
604	sub signal {	1071	sub signal {
605	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
606		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	# not strictly required, as $^F is normally 2, but let's make sure...
		1093	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1095
		1096	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1097	}
		1098
607	my $signal = uc $arg{signal}	1099	my $signal = uc $arg{signal}
608	or Carp::croak "required option 'signal' is missing";	1100	or Carp::croak "required option 'signal' is missing";
609		1101
610	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1102	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
611	$SIG{$signal} ||= sub {	1103	$SIG{$signal} ||= sub {
612	$_->() for values %{ $SIG_CB{$signal} || {} };	1104	local $!;
		1105	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1106	undef $SIG_EV{$signal};
613	};	1107	};
614		1108
615	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1109	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
616	}	1110	}
617		1111
618	sub AnyEvent::Base::Signal::DESTROY {	1112	sub AnyEvent::Base::Signal::DESTROY {
619	my ($signal, $cb) = @{$_[0]};	1113	my ($signal, $cb) = @{$_[0]};
620		1114
621	delete $SIG_CB{$signal}{$cb};	1115	delete $SIG_CB{$signal}{$cb};
622		1116
623	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1117	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
624	}	1118	}
625		1119
626	# default implementation for ->child	1120	# default implementation for ->child
627		1121
628	our %PID_CB;	1122	our %PID_CB;
…		…
655	or Carp::croak "required option 'pid' is missing";	1149	or Carp::croak "required option 'pid' is missing";
656		1150
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1151	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1152
659	unless ($WNOHANG) {	1153	unless ($WNOHANG) {
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1154	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
661	}	1155	}
662		1156
663	unless ($CHLD_W) {	1157	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1158	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
665	# child could be a zombie already, so make at least one round	1159	# child could be a zombie already, so make at least one round
…		…
675	delete $PID_CB{$pid}{$cb};	1169	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1170	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1171
678	undef $CHLD_W unless keys %PID_CB;	1172	undef $CHLD_W unless keys %PID_CB;
679	}	1173	}
		1174
		1175	package AnyEvent::CondVar;
		1176
		1177	our @ISA = AnyEvent::CondVar::Base::;
		1178
		1179	package AnyEvent::CondVar::Base;
		1180
		1181	use overload
		1182	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1183	fallback => 1;
		1184
		1185	sub _send {
		1186	# nop
		1187	}
		1188
		1189	sub send {
		1190	my $cv = shift;
		1191	$cv->{_ae_sent} = [@_];
		1192	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1193	$cv->_send;
		1194	}
		1195
		1196	sub croak {
		1197	$_[0]{_ae_croak} = $_[1];
		1198	$_[0]->send;
		1199	}
		1200
		1201	sub ready {
		1202	$_[0]{_ae_sent}
		1203	}
		1204
		1205	sub _wait {
		1206	AnyEvent->one_event while !$_[0]{_ae_sent};
		1207	}
		1208
		1209	sub recv {
		1210	$_[0]->_wait;
		1211
		1212	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1213	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1214	}
		1215
		1216	sub cb {
		1217	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1218	$_[0]{_ae_cb}
		1219	}
		1220
		1221	sub begin {
		1222	++$_[0]{_ae_counter};
		1223	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1224	}
		1225
		1226	sub end {
		1227	return if --$_[0]{_ae_counter};
		1228	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1229	}
		1230
		1231	# undocumented/compatibility with pre-3.4
		1232	*broadcast = \&send;
		1233	*wait = \&_wait;
		1234
		1235	=head1 ERROR AND EXCEPTION HANDLING
		1236
		1237	In general, AnyEvent does not do any error handling - it relies on the
		1238	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1239	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1240	checking of all AnyEvent methods, however, which is highly useful during
		1241	development.
		1242
		1243	As for exception handling (i.e. runtime errors and exceptions thrown while
		1244	executing a callback), this is not only highly event-loop specific, but
		1245	also not in any way wrapped by this module, as this is the job of the main
		1246	program.
		1247
		1248	The pure perl event loop simply re-throws the exception (usually
		1249	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1250	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1251	so on.
		1252
		1253	=head1 ENVIRONMENT VARIABLES
		1254
		1255	The following environment variables are used by this module or its
		1256	submodules:
		1257
		1258	=over 4
		1259
		1260	=item C<PERL_ANYEVENT_VERBOSE>
		1261
		1262	By default, AnyEvent will be completely silent except in fatal
		1263	conditions. You can set this environment variable to make AnyEvent more
		1264	talkative.
		1265
		1266	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1267	conditions, such as not being able to load the event model specified by
		1268	C<PERL_ANYEVENT_MODEL>.
		1269
		1270	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1271	model it chooses.
		1272
		1273	=item C<PERL_ANYEVENT_STRICT>
		1274
		1275	AnyEvent does not do much argument checking by default, as thorough
		1276	argument checking is very costly. Setting this variable to a true value
		1277	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1278	check the arguments passed to most method calls. If it finds any problems
		1279	it will croak.
		1280
		1281	In other words, enables "strict" mode.
		1282
		1283	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1284	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1285	developing programs can be very useful, however.
		1286
		1287	=item C<PERL_ANYEVENT_MODEL>
		1288
		1289	This can be used to specify the event model to be used by AnyEvent, before
		1290	auto detection and -probing kicks in. It must be a string consisting
		1291	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1292	and the resulting module name is loaded and if the load was successful,
		1293	used as event model. If it fails to load AnyEvent will proceed with
		1294	auto detection and -probing.
		1295
		1296	This functionality might change in future versions.
		1297
		1298	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1299	could start your program like this:
		1300
		1301	PERL_ANYEVENT_MODEL=Perl perl ...
		1302
		1303	=item C<PERL_ANYEVENT_PROTOCOLS>
		1304
		1305	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1306	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1307	of auto probing).
		1308
		1309	Must be set to a comma-separated list of protocols or address families,
		1310	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1311	used, and preference will be given to protocols mentioned earlier in the
		1312	list.
		1313
		1314	This variable can effectively be used for denial-of-service attacks
		1315	against local programs (e.g. when setuid), although the impact is likely
		1316	small, as the program has to handle conenction and other failures anyways.
		1317
		1318	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1319	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1320	- only support IPv4, never try to resolve or contact IPv6
		1321	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1322	IPv6, but prefer IPv6 over IPv4.
		1323
		1324	=item C<PERL_ANYEVENT_EDNS0>
		1325
		1326	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1327	for DNS. This extension is generally useful to reduce DNS traffic, but
		1328	some (broken) firewalls drop such DNS packets, which is why it is off by
		1329	default.
		1330
		1331	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1332	EDNS0 in its DNS requests.
		1333
		1334	=item C<PERL_ANYEVENT_MAX_FORKS>
		1335
		1336	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1337	will create in parallel.
		1338
		1339	=back
680		1340
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1341	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1342
683	This is an advanced topic that you do not normally need to use AnyEvent in	1343	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1344	a module. This section is only of use to event loop authors who want to
…		…
718		1378
719	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1379	I<rxvt-unicode> also cheats a bit by not providing blocking access to
720	condition variables: code blocking while waiting for a condition will	1380	condition variables: code blocking while waiting for a condition will
721	C<die>. This still works with most modules/usages, and blocking calls must	1381	C<die>. This still works with most modules/usages, and blocking calls must
722	not be done in an interactive application, so it makes sense.	1382	not be done in an interactive application, so it makes sense.
723
724	=head1 ENVIRONMENT VARIABLES
725
726	The following environment variables are used by this module:
727
728	=over 4
729
730	=item C<PERL_ANYEVENT_VERBOSE>
731
732	By default, AnyEvent will be completely silent except in fatal
733	conditions. You can set this environment variable to make AnyEvent more
734	talkative.
735
736	When set to C<1> or higher, causes AnyEvent to warn about unexpected
737	conditions, such as not being able to load the event model specified by
738	C<PERL_ANYEVENT_MODEL>.
739
740	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
741	model it chooses.
742
743	=item C<PERL_ANYEVENT_MODEL>
744
745	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.
751
752	This functionality might change in future versions.
753
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:
756
757	PERL_ANYEVENT_MODEL=Perl perl ...
758
759	=back
760		1383
761	=head1 EXAMPLE PROGRAM	1384	=head1 EXAMPLE PROGRAM
762		1385
763	The following program uses an I/O watcher to read data from STDIN, a timer	1386	The following program uses an I/O watcher to read data from STDIN, a timer
764	to display a message once per second, and a condition variable to quit the	1387	to display a message once per second, and a condition variable to quit the
…		…
773	poll => 'r',	1396	poll => 'r',
774	cb => sub {	1397	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1398	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1399	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1400	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1401	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1402	},
780	);	1403	);
781		1404
782	my $time_watcher; # can only be used once	1405	my $time_watcher; # can only be used once
783		1406
…		…
788	});	1411	});
789	}	1412	}
790		1413
791	new_timer; # create first timer	1414	new_timer; # create first timer
792		1415
793	$cv->wait; # wait until user enters /^q/i	1416	$cv->recv; # wait until user enters /^q/i
794		1417
795	=head1 REAL-WORLD EXAMPLE	1418	=head1 REAL-WORLD EXAMPLE
796		1419
797	Consider the L<Net::FCP> module. It features (among others) the following	1420	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	1421	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	1471	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	1472	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1473	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		1474
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1475	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	1476	result and signals any possible waiters that the request has finished:
854		1477
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1478	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		1479
857	if (end-of-file or data complete) {	1480	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	1481	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	1482	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1483	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	1484	}
862		1485
863	The C<result> method, finally, just waits for the finished signal (if the	1486	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	1487	request was already finished, it doesn't wait, of course, and returns the
865	data:	1488	data:
866		1489
867	$txn->{finished}->wait;	1490	$txn->{finished}->recv;
868	return $txn->{result};	1491	return $txn->{result};
869		1492
870	The actual code goes further and collects all errors (C<die>s, exceptions)	1493	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	1494	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	1495	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	1496	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	1497	problems get reported tot he code that tries to use the result, not in a
875	random callback.	1498	random callback.
876		1499
…		…
907		1530
908	my $quit = AnyEvent->condvar;	1531	my $quit = AnyEvent->condvar;
909		1532
910	$fcp->txn_client_get ($url)->cb (sub {	1533	$fcp->txn_client_get ($url)->cb (sub {
911	...	1534	...
912	$quit->broadcast;	1535	$quit->send;
913	});	1536	});
914		1537
915	$quit->wait;	1538	$quit->recv;
916		1539
917		1540
918	=head1 BENCHMARKS	1541	=head1 BENCHMARKS
919		1542
920	To give you an idea of the performance and overheads that AnyEvent adds	1543	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	1545	of various event loops I prepared some benchmarks.
923		1546
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	1547	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		1548
926	Here is a benchmark of various supported event models used natively and	1549	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	1550	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1551	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	1552	which it is), lets them fire exactly once and destroys them again.
930		1553
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1554	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	1555	distribution.
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	1572	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	1573	and memory usage is not included in the figures.
951		1574
952	I<invoke> is the time, in microseconds, used to invoke a simple	1575	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	1576	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1577	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	1578	signal the end of this phase.
956		1579
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	1580	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	1581	watcher.
959		1582
960	=head3 Results	1583	=head3 Results
961		1584
962	name watchers bytes create invoke destroy comment	1585	name watchers bytes create invoke destroy comment
963	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1586	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
964	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1587	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
965	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1588	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
966	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1589	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
967	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1590	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
968	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1591	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
969	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1592	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
970	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1593	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
971	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1594	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
972	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1595	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
973		1596
974	=head3 Discussion	1597	=head3 Discussion
975		1598
976	The benchmark does I<not> measure scalability of the event loop very	1599	The benchmark does I<not> measure scalability of the event loop very
977	well. For example, a select-based event loop (such as the pure perl one)	1600	well. For example, a select-based event loop (such as the pure perl one)
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	1642	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	1643	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	1644	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	1645	above).
1023		1646
1024	C<POE>, regardless of underlying event loop (whether using its pure	1647	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	1648	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	1649	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	1650	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	1651	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	1652	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1653	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1654	implementation.
		1655
1031	implementation. The design of the POE adaptor class in AnyEvent can not	1656	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	1657	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	1658	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1659	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1660	using multiple sessions is not a good approach, especially regarding
		1661	memory usage, even the author of POE could not come up with a faster
		1662	design).
1035		1663
1036	=head3 Summary	1664	=head3 Summary
1037		1665
1038	=over 4	1666	=over 4
1039		1667
…		…
1050		1678
1051	=back	1679	=back
1052		1680
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	1681	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		1682
1055	This benchmark atcually benchmarks the event loop itself. It works by	1683	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	1684	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	1685	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	1686	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	1687	watcher reads a byte it will write that byte to a random other "server".
1060		1688
1061	The effect is that there will be a lot of I/O watchers, only part of which	1689	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	1690	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	1691	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	1692	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	1693	most timeouts work (and puts extra pressure on the event loops).
1066		1694
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1695	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	1696	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	1697	connections, most of which are idle at any one point in time.
1070		1698
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1699	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	1700	distribution.
…		…
1074	=head3 Explanation of the columns	1702	=head3 Explanation of the columns
1075		1703
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	1704	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	1705	each server has a read and write socket end).
1078		1706
1079	I<create> is the time it takes to create a socketpair (which is	1707	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1708	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		1709
1082	I<request>, the most important value, is the time it takes to handle a	1710	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	1711	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	1712	it to another server. This includes deleting the old timeout and creating
…		…
1086		1714
1087	=head3 Results	1715	=head3 Results
1088		1716
1089	name sockets create request	1717	name sockets create request
1090	EV 20000 69.01 11.16	1718	EV 20000 69.01 11.16
1091	Perl 20000 75.28 112.76	1719	Perl 20000 73.32 35.87
1092	Event 20000 212.62 257.32	1720	Event 20000 212.62 257.32
1093	Glib 20000 651.16 1896.30	1721	Glib 20000 651.16 1896.30
1094	POE 20000 349.67 12317.24 uses POE::Loop::Event	1722	POE 20000 349.67 12317.24 uses POE::Loop::Event
1095		1723
1096	=head3 Discussion	1724	=head3 Discussion
…		…
1118		1746
1119	=head3 Summary	1747	=head3 Summary
1120		1748
1121	=over 4	1749	=over 4
1122		1750
1123	=item * The pure perl implementation performs extremely well, considering	1751	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		1752
1126	=item * Avoid Glib or POE in large projects where performance matters.	1753	=item * Avoid Glib or POE in large projects where performance matters.
1127		1754
1128	=back	1755	=back
1129		1756
…		…
1142		1769
1143	=head3 Results	1770	=head3 Results
1144		1771
1145	name sockets create request	1772	name sockets create request
1146	EV 16 20.00 6.54	1773	EV 16 20.00 6.54
		1774	Perl 16 25.75 12.62
1147	Event 16 81.27 35.86	1775	Event 16 81.27 35.86
1148	Glib 16 32.63 15.48	1776	Glib 16 32.63 15.48
1149	Perl 16 24.62 162.37
1150	POE 16 261.87 276.28 uses POE::Loop::Event	1777	POE 16 261.87 276.28 uses POE::Loop::Event
1151		1778
1152	=head3 Discussion	1779	=head3 Discussion
1153		1780
1154	The benchmark tries to test the performance of a typical small	1781	The benchmark tries to test the performance of a typical small
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	1785	speed most when you have lots of watchers, not when you only have a few of
1159	them).	1786	them).
1160		1787
1161	EV is again fastest.	1788	EV is again fastest.
1162		1789
1163	The C-based event loops Event and Glib come in second this time, as the	1790	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	1791	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	1792	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		1793
1170	POE also performs much better in this case, but is is still far behind the	1794	POE also performs much better in this case, but is is still far behind the
1171	others.	1795	others.
1172		1796
1173	=head3 Summary	1797	=head3 Summary
…		…
1178	watchers, as the management overhead dominates.	1802	watchers, as the management overhead dominates.
1179		1803
1180	=back	1804	=back
1181		1805
1182		1806
		1807	=head1 SIGNALS
		1808
		1809	AnyEvent currently installs handlers for these signals:
		1810
		1811	=over 4
		1812
		1813	=item SIGCHLD
		1814
		1815	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1816	emulation for event loops that do not support them natively. Also, some
		1817	event loops install a similar handler.
		1818
		1819	=item SIGPIPE
		1820
		1821	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1822	when AnyEvent gets loaded.
		1823
		1824	The rationale for this is that AnyEvent users usually do not really depend
		1825	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1826	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1827	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1828	some random socket.
		1829
		1830	The rationale for installing a no-op handler as opposed to ignoring it is
		1831	that this way, the handler will be restored to defaults on exec.
		1832
		1833	Feel free to install your own handler, or reset it to defaults.
		1834
		1835	=back
		1836
		1837	=cut
		1838
		1839	$SIG{PIPE} = sub { }
		1840	unless defined $SIG{PIPE};
		1841
		1842
1183	=head1 FORK	1843	=head1 FORK
1184		1844
1185	Most event libraries are not fork-safe. The ones who are usually are	1845	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	1846	because they rely on inefficient but fork-safe C<select> or C<poll>
		1847	calls. Only L<EV> is fully fork-aware.
1187		1848
1188	If you have to fork, you must either do so I<before> creating your first	1849	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	1850	watcher OR you must not use AnyEvent at all in the child.
1190		1851
1191		1852
…		…
1199	specified in the variable.	1860	specified in the variable.
1200		1861
1201	You can make AnyEvent completely ignore this variable by deleting it	1862	You can make AnyEvent completely ignore this variable by deleting it
1202	before the first watcher gets created, e.g. with a C<BEGIN> block:	1863	before the first watcher gets created, e.g. with a C<BEGIN> block:
1203		1864
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1865	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		1866
1206	use AnyEvent;	1867	use AnyEvent;
		1868
		1869	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1870	be used to probe what backend is used and gain other information (which is
		1871	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1872	$ENV{PERL_ANYEGENT_STRICT}.
		1873
		1874
		1875	=head1 BUGS
		1876
		1877	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1878	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1879	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1880	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1881	pronounced).
1207		1882
1208		1883
1209	=head1 SEE ALSO	1884	=head1 SEE ALSO
1210		1885
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1886	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1887
		1888	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	1889	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		1890
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1891	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1892	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1893	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1894	L<AnyEvent::Impl::POE>.
1219		1895
		1896	Non-blocking file handles, sockets, TCP clients and
		1897	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1898
		1899	Asynchronous DNS: L<AnyEvent::DNS>.
		1900
		1901	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1902
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1903	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1221		1904
1222		1905
1223	=head1 AUTHOR	1906	=head1 AUTHOR
1224		1907
1225	Marc Lehmann <schmorp@schmorp.de>	1908	Marc Lehmann <schmorp@schmorp.de>
1226	http://home.schmorp.de/	1909	http://home.schmorp.de/
1227		1910
1228	=cut	1911	=cut
1229		1912
1230	1	1913	1
1231		1914

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