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Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs.
Revision 1.201 by root, Wed Apr 1 14:08:27 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
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
481		774
482	=head1 OTHER MODULES	775	=head1 OTHER MODULES
483		776
484	L<AnyEvent> itself comes with useful utility modules:	777	The following is a non-exhaustive list of additional modules that use
485		778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
486	To make it easier to do non-blocking IO the modules L<AnyEvent::Handle>	779	in the same program. Some of the modules come with AnyEvent, some are
487	and L<AnyEvent::Socket> are provided. L<AnyEvent::Handle> provides	780	available via CPAN.
488	read and write buffers and manages watchers for reads and writes.
489	L<AnyEvent::Socket> provides means to do non-blocking connects.
490
491	Aside from those there are these modules that support AnyEvent (and use it
492	for non-blocking IO):
493		781
494	=over 4	782	=over 4
495		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
496	=item L<AnyEvent::FastPing>	814	=item L<AnyEvent::FastPing>
497		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
498	=item L<Net::IRC3>	842	=item L<AnyEvent::IRC>
		843
		844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
499		845
500	=item L<Net::XMPP2>	846	=item L<Net::XMPP2>
501		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
502	=back	867	=back
503		868
504	=cut	869	=cut
505		870
506	package AnyEvent;	871	package AnyEvent;
507		872
508	no warnings;	873	no warnings;
509	use strict;	874	use strict qw(vars subs);
510		875
511	use Carp;	876	use Carp;
512		877
513	our $VERSION = '3.3';	878	our $VERSION = 4.35;
514	our $MODEL;	879	our $MODEL;
515		880
516	our $AUTOLOAD;	881	our $AUTOLOAD;
517	our @ISA;	882	our @ISA;
518		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
519	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
520		894
521	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	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		902	}
522		903
523	my @models = (	904	my @models = (
524	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
525	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
526	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
527	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
528	[Glib:: => AnyEvent::Impl::Glib::],
529	[Tk:: => AnyEvent::Impl::Tk::],
530	[Wx:: => AnyEvent::Impl::POE::],
531	[Prima:: => AnyEvent::Impl::POE::],
532	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
533	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
		909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
534	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
535	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
536	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
537	);	918	);
538		919
539	our %method = map +($_ => 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	}
540		943
541	sub detect() {	944	sub detect() {
542	unless ($MODEL) {	945	unless ($MODEL) {
543	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
544		948
545	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
546	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
547	if (eval "require $model") {	951	if (eval "require $model") {
548	$MODEL = $model;	952	$MODEL = $model;
…		…
578	last;	982	last;
579	}	983	}
580	}	984	}
581		985
582	$MODEL	986	$MODEL
583	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
584	}	988	}
585	}	989	}
586		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
587	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
588	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		996
		997	(shift @post_detect)->() while @post_detect;
589	}	998	}
590		999
591	$MODEL	1000	$MODEL
592	}	1001	}
593		1002
…		…
601		1010
602	my $class = shift;	1011	my $class = shift;
603	$class->$func (@_);	1012	$class->$func (@_);
604	}	1013	}
605		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
606	package AnyEvent::Base;	1034	package AnyEvent::Base;
607		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
608	# default implementation for ->condvar, ->wait, ->broadcast	1050	# default implementation for ->condvar
609		1051
610	sub condvar {	1052	sub condvar {
611	bless \my $flag, "AnyEvent::Base::CondVar"	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
612	}
613
614	sub AnyEvent::Base::CondVar::broadcast {
615	${$_[0]}++;
616	}
617
618	sub AnyEvent::Base::CondVar::wait {
619	AnyEvent->one_event while !${$_[0]};
620	}	1054	}
621		1055
622	# default implementation for ->signal	1056	# default implementation for ->signal
623		1057
624	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	}
625		1070
626	sub signal {	1071	sub signal {
627	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
628		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
629	my $signal = uc $arg{signal}	1099	my $signal = uc $arg{signal}
630	or Carp::croak "required option 'signal' is missing";	1100	or Carp::croak "required option 'signal' is missing";
631		1101
632	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1102	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
633	$SIG{$signal} ||= sub {	1103	$SIG{$signal} ||= sub {
634	$_->() for values %{ $SIG_CB{$signal} || {} };	1104	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1105	undef $SIG_EV{$signal};
635	};	1106	};
636		1107
637	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1108	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
638	}	1109	}
639		1110
640	sub AnyEvent::Base::Signal::DESTROY {	1111	sub AnyEvent::Base::Signal::DESTROY {
641	my ($signal, $cb) = @{$_[0]};	1112	my ($signal, $cb) = @{$_[0]};
642		1113
643	delete $SIG_CB{$signal}{$cb};	1114	delete $SIG_CB{$signal}{$cb};
644		1115
645	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1116	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
646	}	1117	}
647		1118
648	# default implementation for ->child	1119	# default implementation for ->child
649		1120
650	our %PID_CB;	1121	our %PID_CB;
…		…
677	or Carp::croak "required option 'pid' is missing";	1148	or Carp::croak "required option 'pid' is missing";
678		1149
679	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1150	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
680		1151
681	unless ($WNOHANG) {	1152	unless ($WNOHANG) {
682	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1153	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
683	}	1154	}
684		1155
685	unless ($CHLD_W) {	1156	unless ($CHLD_W) {
686	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1157	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
687	# child could be a zombie already, so make at least one round	1158	# child could be a zombie already, so make at least one round
…		…
697	delete $PID_CB{$pid}{$cb};	1168	delete $PID_CB{$pid}{$cb};
698	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1169	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
699		1170
700	undef $CHLD_W unless keys %PID_CB;	1171	undef $CHLD_W unless keys %PID_CB;
701	}	1172	}
		1173
		1174	package AnyEvent::CondVar;
		1175
		1176	our @ISA = AnyEvent::CondVar::Base::;
		1177
		1178	package AnyEvent::CondVar::Base;
		1179
		1180	use overload
		1181	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1182	fallback => 1;
		1183
		1184	sub _send {
		1185	# nop
		1186	}
		1187
		1188	sub send {
		1189	my $cv = shift;
		1190	$cv->{_ae_sent} = [@_];
		1191	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1192	$cv->_send;
		1193	}
		1194
		1195	sub croak {
		1196	$_[0]{_ae_croak} = $_[1];
		1197	$_[0]->send;
		1198	}
		1199
		1200	sub ready {
		1201	$_[0]{_ae_sent}
		1202	}
		1203
		1204	sub _wait {
		1205	AnyEvent->one_event while !$_[0]{_ae_sent};
		1206	}
		1207
		1208	sub recv {
		1209	$_[0]->_wait;
		1210
		1211	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1212	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1213	}
		1214
		1215	sub cb {
		1216	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1217	$_[0]{_ae_cb}
		1218	}
		1219
		1220	sub begin {
		1221	++$_[0]{_ae_counter};
		1222	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1223	}
		1224
		1225	sub end {
		1226	return if --$_[0]{_ae_counter};
		1227	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1228	}
		1229
		1230	# undocumented/compatibility with pre-3.4
		1231	*broadcast = \&send;
		1232	*wait = \&_wait;
		1233
		1234	=head1 ERROR AND EXCEPTION HANDLING
		1235
		1236	In general, AnyEvent does not do any error handling - it relies on the
		1237	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1238	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1239	checking of all AnyEvent methods, however, which is highly useful during
		1240	development.
		1241
		1242	As for exception handling (i.e. runtime errors and exceptions thrown while
		1243	executing a callback), this is not only highly event-loop specific, but
		1244	also not in any way wrapped by this module, as this is the job of the main
		1245	program.
		1246
		1247	The pure perl event loop simply re-throws the exception (usually
		1248	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1249	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1250	so on.
		1251
		1252	=head1 ENVIRONMENT VARIABLES
		1253
		1254	The following environment variables are used by this module or its
		1255	submodules:
		1256
		1257	=over 4
		1258
		1259	=item C<PERL_ANYEVENT_VERBOSE>
		1260
		1261	By default, AnyEvent will be completely silent except in fatal
		1262	conditions. You can set this environment variable to make AnyEvent more
		1263	talkative.
		1264
		1265	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1266	conditions, such as not being able to load the event model specified by
		1267	C<PERL_ANYEVENT_MODEL>.
		1268
		1269	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1270	model it chooses.
		1271
		1272	=item C<PERL_ANYEVENT_STRICT>
		1273
		1274	AnyEvent does not do much argument checking by default, as thorough
		1275	argument checking is very costly. Setting this variable to a true value
		1276	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1277	check the arguments passed to most method calls. If it finds any problems
		1278	it will croak.
		1279
		1280	In other words, enables "strict" mode.
		1281
		1282	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1283	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1284	developing programs can be very useful, however.
		1285
		1286	=item C<PERL_ANYEVENT_MODEL>
		1287
		1288	This can be used to specify the event model to be used by AnyEvent, before
		1289	auto detection and -probing kicks in. It must be a string consisting
		1290	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1291	and the resulting module name is loaded and if the load was successful,
		1292	used as event model. If it fails to load AnyEvent will proceed with
		1293	auto detection and -probing.
		1294
		1295	This functionality might change in future versions.
		1296
		1297	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1298	could start your program like this:
		1299
		1300	PERL_ANYEVENT_MODEL=Perl perl ...
		1301
		1302	=item C<PERL_ANYEVENT_PROTOCOLS>
		1303
		1304	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1305	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1306	of auto probing).
		1307
		1308	Must be set to a comma-separated list of protocols or address families,
		1309	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1310	used, and preference will be given to protocols mentioned earlier in the
		1311	list.
		1312
		1313	This variable can effectively be used for denial-of-service attacks
		1314	against local programs (e.g. when setuid), although the impact is likely
		1315	small, as the program has to handle conenction and other failures anyways.
		1316
		1317	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1318	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1319	- only support IPv4, never try to resolve or contact IPv6
		1320	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1321	IPv6, but prefer IPv6 over IPv4.
		1322
		1323	=item C<PERL_ANYEVENT_EDNS0>
		1324
		1325	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1326	for DNS. This extension is generally useful to reduce DNS traffic, but
		1327	some (broken) firewalls drop such DNS packets, which is why it is off by
		1328	default.
		1329
		1330	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1331	EDNS0 in its DNS requests.
		1332
		1333	=item C<PERL_ANYEVENT_MAX_FORKS>
		1334
		1335	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1336	will create in parallel.
		1337
		1338	=back
702		1339
703	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1340	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
704		1341
705	This is an advanced topic that you do not normally need to use AnyEvent in	1342	This is an advanced topic that you do not normally need to use AnyEvent in
706	a module. This section is only of use to event loop authors who want to	1343	a module. This section is only of use to event loop authors who want to
…		…
740		1377
741	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1378	I<rxvt-unicode> also cheats a bit by not providing blocking access to
742	condition variables: code blocking while waiting for a condition will	1379	condition variables: code blocking while waiting for a condition will
743	C<die>. This still works with most modules/usages, and blocking calls must	1380	C<die>. This still works with most modules/usages, and blocking calls must
744	not be done in an interactive application, so it makes sense.	1381	not be done in an interactive application, so it makes sense.
745
746	=head1 ENVIRONMENT VARIABLES
747
748	The following environment variables are used by this module:
749
750	=over 4
751
752	=item C<PERL_ANYEVENT_VERBOSE>
753
754	By default, AnyEvent will be completely silent except in fatal
755	conditions. You can set this environment variable to make AnyEvent more
756	talkative.
757
758	When set to C<1> or higher, causes AnyEvent to warn about unexpected
759	conditions, such as not being able to load the event model specified by
760	C<PERL_ANYEVENT_MODEL>.
761
762	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
763	model it chooses.
764
765	=item C<PERL_ANYEVENT_MODEL>
766
767	This can be used to specify the event model to be used by AnyEvent, before
768	autodetection and -probing kicks in. It must be a string consisting
769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
770	and the resulting module name is loaded and if the load was successful,
771	used as event model. If it fails to load AnyEvent will proceed with
772	autodetection and -probing.
773
774	This functionality might change in future versions.
775
776	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
777	could start your program like this:
778
779	PERL_ANYEVENT_MODEL=Perl perl ...
780
781	=back
782		1382
783	=head1 EXAMPLE PROGRAM	1383	=head1 EXAMPLE PROGRAM
784		1384
785	The following program uses an I/O watcher to read data from STDIN, a timer	1385	The following program uses an I/O watcher to read data from STDIN, a timer
786	to display a message once per second, and a condition variable to quit the	1386	to display a message once per second, and a condition variable to quit the
…		…
795	poll => 'r',	1395	poll => 'r',
796	cb => sub {	1396	cb => sub {
797	warn "io event <$_[0]>\n"; # will always output <r>	1397	warn "io event <$_[0]>\n"; # will always output <r>
798	chomp (my $input = <STDIN>); # read a line	1398	chomp (my $input = <STDIN>); # read a line
799	warn "read: $input\n"; # output what has been read	1399	warn "read: $input\n"; # output what has been read
800	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1400	$cv->send if $input =~ /^q/i; # quit program if /^q/i
801	},	1401	},
802	);	1402	);
803		1403
804	my $time_watcher; # can only be used once	1404	my $time_watcher; # can only be used once
805		1405
…		…
810	});	1410	});
811	}	1411	}
812		1412
813	new_timer; # create first timer	1413	new_timer; # create first timer
814		1414
815	$cv->wait; # wait until user enters /^q/i	1415	$cv->recv; # wait until user enters /^q/i
816		1416
817	=head1 REAL-WORLD EXAMPLE	1417	=head1 REAL-WORLD EXAMPLE
818		1418
819	Consider the L<Net::FCP> module. It features (among others) the following	1419	Consider the L<Net::FCP> module. It features (among others) the following
820	API calls, which are to freenet what HTTP GET requests are to http:	1420	API calls, which are to freenet what HTTP GET requests are to http:
…		…
870	syswrite $txn->{fh}, $txn->{request}	1470	syswrite $txn->{fh}, $txn->{request}
871	or die "connection or write error";	1471	or die "connection or write error";
872	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1472	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
873		1473
874	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1474	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
875	result and signals any possible waiters that the request ahs finished:	1475	result and signals any possible waiters that the request has finished:
876		1476
877	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1477	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
878		1478
879	if (end-of-file or data complete) {	1479	if (end-of-file or data complete) {
880	$txn->{result} = $txn->{buf};	1480	$txn->{result} = $txn->{buf};
881	$txn->{finished}->broadcast;	1481	$txn->{finished}->send;
882	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1482	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
883	}	1483	}
884		1484
885	The C<result> method, finally, just waits for the finished signal (if the	1485	The C<result> method, finally, just waits for the finished signal (if the
886	request was already finished, it doesn't wait, of course, and returns the	1486	request was already finished, it doesn't wait, of course, and returns the
887	data:	1487	data:
888		1488
889	$txn->{finished}->wait;	1489	$txn->{finished}->recv;
890	return $txn->{result};	1490	return $txn->{result};
891		1491
892	The actual code goes further and collects all errors (C<die>s, exceptions)	1492	The actual code goes further and collects all errors (C<die>s, exceptions)
893	that occured during request processing. The C<result> method detects	1493	that occurred during request processing. The C<result> method detects
894	whether an exception as thrown (it is stored inside the $txn object)	1494	whether an exception as thrown (it is stored inside the $txn object)
895	and just throws the exception, which means connection errors and other	1495	and just throws the exception, which means connection errors and other
896	problems get reported tot he code that tries to use the result, not in a	1496	problems get reported tot he code that tries to use the result, not in a
897	random callback.	1497	random callback.
898		1498
…		…
929		1529
930	my $quit = AnyEvent->condvar;	1530	my $quit = AnyEvent->condvar;
931		1531
932	$fcp->txn_client_get ($url)->cb (sub {	1532	$fcp->txn_client_get ($url)->cb (sub {
933	...	1533	...
934	$quit->broadcast;	1534	$quit->send;
935	});	1535	});
936		1536
937	$quit->wait;	1537	$quit->recv;
938		1538
939		1539
940	=head1 BENCHMARKS	1540	=head1 BENCHMARKS
941		1541
942	To give you an idea of the performance and overheads that AnyEvent adds	1542	To give you an idea of the performance and overheads that AnyEvent adds
…		…
944	of various event loops I prepared some benchmarks.	1544	of various event loops I prepared some benchmarks.
945		1545
946	=head2 BENCHMARKING ANYEVENT OVERHEAD	1546	=head2 BENCHMARKING ANYEVENT OVERHEAD
947		1547
948	Here is a benchmark of various supported event models used natively and	1548	Here is a benchmark of various supported event models used natively and
949	through anyevent. The benchmark creates a lot of timers (with a zero	1549	through AnyEvent. The benchmark creates a lot of timers (with a zero
950	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1550	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
951	which it is), lets them fire exactly once and destroys them again.	1551	which it is), lets them fire exactly once and destroys them again.
952		1552
953	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1553	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
954	distribution.	1554	distribution.
…		…
971	all watchers, to avoid adding memory overhead. That means closure creation	1571	all watchers, to avoid adding memory overhead. That means closure creation
972	and memory usage is not included in the figures.	1572	and memory usage is not included in the figures.
973		1573
974	I<invoke> is the time, in microseconds, used to invoke a simple	1574	I<invoke> is the time, in microseconds, used to invoke a simple
975	callback. The callback simply counts down a Perl variable and after it was	1575	callback. The callback simply counts down a Perl variable and after it was
976	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1576	invoked "watcher" times, it would C<< ->send >> a condvar once to
977	signal the end of this phase.	1577	signal the end of this phase.
978		1578
979	I<destroy> is the time, in microseconds, that it takes to destroy a single	1579	I<destroy> is the time, in microseconds, that it takes to destroy a single
980	watcher.	1580	watcher.
981		1581
982	=head3 Results	1582	=head3 Results
983		1583
984	name watchers bytes create invoke destroy comment	1584	name watchers bytes create invoke destroy comment
985	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1585	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
986	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1586	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
987	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1587	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
988	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1588	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
989	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1589	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
990	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1590	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
991	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1591	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
992	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1592	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
993	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1593	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
994	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1594	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
995		1595
996	=head3 Discussion	1596	=head3 Discussion
997		1597
998	The benchmark does I<not> measure scalability of the event loop very	1598	The benchmark does I<not> measure scalability of the event loop very
999	well. For example, a select-based event loop (such as the pure perl one)	1599	well. For example, a select-based event loop (such as the pure perl one)
…		…
1041	file descriptor is dup()ed for each watcher. This shows that the dup()	1641	file descriptor is dup()ed for each watcher. This shows that the dup()
1042	employed by some adaptors is not a big performance issue (it does incur a	1642	employed by some adaptors is not a big performance issue (it does incur a
1043	hidden memory cost inside the kernel which is not reflected in the figures	1643	hidden memory cost inside the kernel which is not reflected in the figures
1044	above).	1644	above).
1045		1645
1046	C<POE>, regardless of underlying event loop (whether using its pure	1646	C<POE>, regardless of underlying event loop (whether using its pure perl
1047	perl select-based backend or the Event module, the POE-EV backend	1647	select-based backend or the Event module, the POE-EV backend couldn't
1048	couldn't be tested because it wasn't working) shows abysmal performance	1648	be tested because it wasn't working) shows abysmal performance and
1049	and memory usage: Watchers use almost 30 times as much memory as	1649	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1050	EV watchers, and 10 times as much memory as Event (the high memory	1650	as EV watchers, and 10 times as much memory as Event (the high memory
1051	requirements are caused by requiring a session for each watcher). Watcher	1651	requirements are caused by requiring a session for each watcher). Watcher
1052	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1652	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1653	implementation.
		1654
1053	implementation. The design of the POE adaptor class in AnyEvent can not	1655	The design of the POE adaptor class in AnyEvent can not really account
1054	really account for this, as session creation overhead is small compared	1656	for the performance issues, though, as session creation overhead is
1055	to execution of the state machine, which is coded pretty optimally within	1657	small compared to execution of the state machine, which is coded pretty
1056	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1658	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1659	using multiple sessions is not a good approach, especially regarding
		1660	memory usage, even the author of POE could not come up with a faster
		1661	design).
1057		1662
1058	=head3 Summary	1663	=head3 Summary
1059		1664
1060	=over 4	1665	=over 4
1061		1666
…		…
1072		1677
1073	=back	1678	=back
1074		1679
1075	=head2 BENCHMARKING THE LARGE SERVER CASE	1680	=head2 BENCHMARKING THE LARGE SERVER CASE
1076		1681
1077	This benchmark atcually benchmarks the event loop itself. It works by	1682	This benchmark actually benchmarks the event loop itself. It works by
1078	creating a number of "servers": each server consists of a socketpair, a	1683	creating a number of "servers": each server consists of a socket pair, a
1079	timeout watcher that gets reset on activity (but never fires), and an I/O	1684	timeout watcher that gets reset on activity (but never fires), and an I/O
1080	watcher waiting for input on one side of the socket. Each time the socket	1685	watcher waiting for input on one side of the socket. Each time the socket
1081	watcher reads a byte it will write that byte to a random other "server".	1686	watcher reads a byte it will write that byte to a random other "server".
1082		1687
1083	The effect is that there will be a lot of I/O watchers, only part of which	1688	The effect is that there will be a lot of I/O watchers, only part of which
1084	are active at any one point (so there is a constant number of active	1689	are active at any one point (so there is a constant number of active
1085	fds for each loop iterstaion, but which fds these are is random). The	1690	fds for each loop iteration, but which fds these are is random). The
1086	timeout is reset each time something is read because that reflects how	1691	timeout is reset each time something is read because that reflects how
1087	most timeouts work (and puts extra pressure on the event loops).	1692	most timeouts work (and puts extra pressure on the event loops).
1088		1693
1089	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1694	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1090	(1%) are active. This mirrors the activity of large servers with many	1695	(1%) are active. This mirrors the activity of large servers with many
1091	connections, most of which are idle at any one point in time.	1696	connections, most of which are idle at any one point in time.
1092		1697
1093	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1698	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1094	distribution.	1699	distribution.
…		…
1096	=head3 Explanation of the columns	1701	=head3 Explanation of the columns
1097		1702
1098	I<sockets> is the number of sockets, and twice the number of "servers" (as	1703	I<sockets> is the number of sockets, and twice the number of "servers" (as
1099	each server has a read and write socket end).	1704	each server has a read and write socket end).
1100		1705
1101	I<create> is the time it takes to create a socketpair (which is	1706	I<create> is the time it takes to create a socket pair (which is
1102	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1707	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1103		1708
1104	I<request>, the most important value, is the time it takes to handle a	1709	I<request>, the most important value, is the time it takes to handle a
1105	single "request", that is, reading the token from the pipe and forwarding	1710	single "request", that is, reading the token from the pipe and forwarding
1106	it to another server. This includes deleting the old timeout and creating	1711	it to another server. This includes deleting the old timeout and creating
…		…
1140		1745
1141	=head3 Summary	1746	=head3 Summary
1142		1747
1143	=over 4	1748	=over 4
1144		1749
1145	=item * The pure perl implementation performs extremely well, considering	1750	=item * The pure perl implementation performs extremely well.
1146	that it uses select.
1147		1751
1148	=item * Avoid Glib or POE in large projects where performance matters.	1752	=item * Avoid Glib or POE in large projects where performance matters.
1149		1753
1150	=back	1754	=back
1151		1755
…		…
1180	speed most when you have lots of watchers, not when you only have a few of	1784	speed most when you have lots of watchers, not when you only have a few of
1181	them).	1785	them).
1182		1786
1183	EV is again fastest.	1787	EV is again fastest.
1184		1788
1185	The C-based event loops Event and Glib come in second this time, as the	1789	Perl again comes second. It is noticeably faster than the C-based event
1186	overhead of running an iteration is much smaller in C than in Perl (little	1790	loops Event and Glib, although the difference is too small to really
1187	code to execute in the inner loop, and perl's function calling overhead is	1791	matter.
1188	high, and updating all the data structures is costly).
1189
1190	The pure perl event loop is much slower, but still competitive.
1191		1792
1192	POE also performs much better in this case, but is is still far behind the	1793	POE also performs much better in this case, but is is still far behind the
1193	others.	1794	others.
1194		1795
1195	=head3 Summary	1796	=head3 Summary
…		…
1200	watchers, as the management overhead dominates.	1801	watchers, as the management overhead dominates.
1201		1802
1202	=back	1803	=back
1203		1804
1204		1805
		1806	=head1 SIGNALS
		1807
		1808	AnyEvent currently installs handlers for these signals:
		1809
		1810	=over 4
		1811
		1812	=item SIGCHLD
		1813
		1814	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1815	emulation for event loops that do not support them natively. Also, some
		1816	event loops install a similar handler.
		1817
		1818	=item SIGPIPE
		1819
		1820	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1821	when AnyEvent gets loaded.
		1822
		1823	The rationale for this is that AnyEvent users usually do not really depend
		1824	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1825	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1826	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1827	some random socket.
		1828
		1829	The rationale for installing a no-op handler as opposed to ignoring it is
		1830	that this way, the handler will be restored to defaults on exec.
		1831
		1832	Feel free to install your own handler, or reset it to defaults.
		1833
		1834	=back
		1835
		1836	=cut
		1837
		1838	$SIG{PIPE} = sub { }
		1839	unless defined $SIG{PIPE};
		1840
		1841
1205	=head1 FORK	1842	=head1 FORK
1206		1843
1207	Most event libraries are not fork-safe. The ones who are usually are	1844	Most event libraries are not fork-safe. The ones who are usually are
1208	because they are so inefficient. Only L<EV> is fully fork-aware.	1845	because they rely on inefficient but fork-safe C<select> or C<poll>
		1846	calls. Only L<EV> is fully fork-aware.
1209		1847
1210	If you have to fork, you must either do so I<before> creating your first	1848	If you have to fork, you must either do so I<before> creating your first
1211	watcher OR you must not use AnyEvent at all in the child.	1849	watcher OR you must not use AnyEvent at all in the child.
1212		1850
1213		1851
…		…
1221	specified in the variable.	1859	specified in the variable.
1222		1860
1223	You can make AnyEvent completely ignore this variable by deleting it	1861	You can make AnyEvent completely ignore this variable by deleting it
1224	before the first watcher gets created, e.g. with a C<BEGIN> block:	1862	before the first watcher gets created, e.g. with a C<BEGIN> block:
1225		1863
1226	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1864	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1227		1865
1228	use AnyEvent;	1866	use AnyEvent;
		1867
		1868	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1869	be used to probe what backend is used and gain other information (which is
		1870	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1871	$ENV{PERL_ANYEGENT_STRICT}.
		1872
		1873
		1874	=head1 BUGS
		1875
		1876	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1877	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1878	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1879	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1880	pronounced).
1229		1881
1230		1882
1231	=head1 SEE ALSO	1883	=head1 SEE ALSO
1232		1884
1233	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1885	Utility functions: L<AnyEvent::Util>.
1234	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1886
		1887	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1235	L<Event::Lib>, L<Qt>, L<POE>.	1888	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1236		1889
1237	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1890	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1238	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1891	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1239	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1892	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1240	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1893	L<AnyEvent::Impl::POE>.
1241		1894
		1895	Non-blocking file handles, sockets, TCP clients and
		1896	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1897
		1898	Asynchronous DNS: L<AnyEvent::DNS>.
		1899
		1900	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1901
1242	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1902	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1243		1903
1244		1904
1245	=head1 AUTHOR	1905	=head1 AUTHOR
1246		1906
1247	Marc Lehmann <schmorp@schmorp.de>	1907	Marc Lehmann <schmorp@schmorp.de>
1248	http://home.schmorp.de/	1908	http://home.schmorp.de/
1249		1909
1250	=cut	1910	=cut
1251		1911
1252	1	1912	1
1253		1913

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