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Revision 1.215 by root, Tue Jun 23 12:19:33 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, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->send; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
114		144
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
242	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
246		364
247	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	366	between multiple watchers.
249		367
250	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
260		378
261	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	402	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		404
280	Example: fork a process and wait for it	405	Example: fork a process and wait for it
281		406
282	my $done = AnyEvent->condvar;	407	my $done = AnyEvent->condvar;
283		408
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	409	my $pid = fork or exit 5;
287		410
288	my $w = AnyEvent->child (	411	my $w = AnyEvent->child (
289	pid => $pid,	412	pid => $pid,
290	cb => sub {	413	cb => sub {
291	my ($pid, $status) = @_;	414	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	415	warn "pid $pid exited with status $status";
293	$done->send;	416	$done->send;
294	},	417	},
295	);	418	);
296		419
297	# do something else, then wait for process exit	420	# do something else, then wait for process exit
298	$done->wait;	421	$done->recv;
		422
		423	=head2 IDLE WATCHERS
		424
		425	Sometimes there is a need to do something, but it is not so important
		426	to do it instantly, but only when there is nothing better to do. This
		427	"nothing better to do" is usually defined to be "no other events need
		428	attention by the event loop".
		429
		430	Idle watchers ideally get invoked when the event loop has nothing
		431	better to do, just before it would block the process to wait for new
		432	events. Instead of blocking, the idle watcher is invoked.
		433
		434	Most event loops unfortunately do not really support idle watchers (only
		435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		436	will simply call the callback "from time to time".
		437
		438	Example: read lines from STDIN, but only process them when the
		439	program is otherwise idle:
		440
		441	my @lines; # read data
		442	my $idle_w;
		443	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		444	push @lines, scalar <STDIN>;
		445
		446	# start an idle watcher, if not already done
		447	$idle_w ||= AnyEvent->idle (cb => sub {
		448	# handle only one line, when there are lines left
		449	if (my $line = shift @lines) {
		450	print "handled when idle: $line";
		451	} else {
		452	# otherwise disable the idle watcher again
		453	undef $idle_w;
		454	}
		455	});
		456	});
299		457
300	=head2 CONDITION VARIABLES	458	=head2 CONDITION VARIABLES
301		459
302	If you are familiar with some event loops you will know that all of them	460	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	461	require you to run some blocking "loop", "run" or similar function that
…		…
309	The instrument to do that is called a "condition variable", so called	467	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	468	because they represent a condition that must become true.
311		469
312	Condition variables can be created by calling the C<< AnyEvent->condvar	470	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	471	>> method, usually without arguments. The only argument pair allowed is
		472
314	C<cb>, which specifies a callback to be called when the condition variable	473	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	474	becomes true, with the condition variable as the first argument (but not
		475	the results).
316		476
317	After creation, the conditon variable is "false" until it becomes "true"	477	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<send> method.	478	by calling the C<send> method (or calling the condition variable as if it
		479	were a callback, read about the caveats in the description for the C<<
		480	->send >> method).
319		481
320	Condition variables are similar to callbacks, except that you can	482	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	483	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	484	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	485	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	486	used to represent a transaction, which finishes at some point and delivers
325	a result.	487	a result.
326		488
327	Condition variables are very useful to signal that something has finished,	489	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	490	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	491	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	492	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	493	called or can synchronously C<< ->recv >> for the results.
332		494
333	You can also use them to simulate traditional event loops - for example,	495	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	496	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	497	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->send >> the "quit" event.	498	button of your app, which would C<< ->send >> the "quit" event.
337		499
338	Note that condition variables recurse into the event loop - if you have	500	Note that condition variables recurse into the event loop - if you have
339	two pieces of code that call C<< ->wait >> in a round-robbin fashion, you	501	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	502	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,	503	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	504	as this asks for trouble.
343		505
344	Condition variables are represented by hash refs in perl, and the keys	506	Condition variables are represented by hash refs in perl, and the keys
…		…
349		511
350	There are two "sides" to a condition variable - the "producer side" which	512	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> send >>, and the "consumer side", which waits	513	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the send to occur.	514	for the send to occur.
353		515
354	Example:	516	Example: wait for a timer.
355		517
356	# wait till the result is ready	518	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	519	my $result_ready = AnyEvent->condvar;
358		520
359	# do something such as adding a timer	521	# do something such as adding a timer
…		…
365	cb => sub { $result_ready->send },	527	cb => sub { $result_ready->send },
366	);	528	);
367		529
368	# this "blocks" (while handling events) till the callback	530	# this "blocks" (while handling events) till the callback
369	# calls send	531	# calls send
370	$result_ready->wait;	532	$result_ready->recv;
		533
		534	Example: wait for a timer, but take advantage of the fact that
		535	condition variables are also code references.
		536
		537	my $done = AnyEvent->condvar;
		538	my $delay = AnyEvent->timer (after => 5, cb => $done);
		539	$done->recv;
		540
		541	Example: Imagine an API that returns a condvar and doesn't support
		542	callbacks. This is how you make a synchronous call, for example from
		543	the main program:
		544
		545	use AnyEvent::CouchDB;
		546
		547	...
		548
		549	my @info = $couchdb->info->recv;
		550
		551	And this is how you would just ste a callback to be called whenever the
		552	results are available:
		553
		554	$couchdb->info->cb (sub {
		555	my @info = $_[0]->recv;
		556	});
371		557
372	=head3 METHODS FOR PRODUCERS	558	=head3 METHODS FOR PRODUCERS
373		559
374	These methods should only be used by the producing side, i.e. the	560	These methods should only be used by the producing side, i.e. the
375	code/module that eventually sends the signal. Note that it is also	561	code/module that eventually sends the signal. Note that it is also
…		…
378		564
379	=over 4	565	=over 4
380		566
381	=item $cv->send (...)	567	=item $cv->send (...)
382		568
383	Flag the condition as ready - a running C<< ->wait >> and all further	569	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	570	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the send will be remembered.	571	called. If nobody is waiting the send will be remembered.
386		572
387	If a callback has been set on the condition variable, it is called	573	If a callback has been set on the condition variable, it is called
388	immediately from within send.	574	immediately from within send.
389		575
390	Any arguments passed to the C<send> call will be returned by all	576	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	577	future C<< ->recv >> calls.
		578
		579	Condition variables are overloaded so one can call them directly
		580	(as a code reference). Calling them directly is the same as calling
		581	C<send>. Note, however, that many C-based event loops do not handle
		582	overloading, so as tempting as it may be, passing a condition variable
		583	instead of a callback does not work. Both the pure perl and EV loops
		584	support overloading, however, as well as all functions that use perl to
		585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		586	example).
392		587
393	=item $cv->croak ($error)	588	=item $cv->croak ($error)
394		589
395	Similar to send, but causes all call's wait C<< ->wait >> to invoke	590	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	591	C<Carp::croak> with the given error message/object/scalar.
397		592
398	This can be used to signal any errors to the condition variable	593	This can be used to signal any errors to the condition variable
399	user/consumer.	594	user/consumer.
400		595
401	=item $cv->begin ([group callback])	596	=item $cv->begin ([group callback])
402		597
403	=item $cv->end	598	=item $cv->end
		599
		600	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		601
405	These two methods can be used to combine many transactions/events into	602	These two methods can be used to combine many transactions/events into
406	one. For example, a function that pings many hosts in parallel might want	603	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	604	to use a condition variable for the whole process.
408		605
…		…
443	doesn't execute once).	640	doesn't execute once).
444		641
445	This is the general pattern when you "fan out" into multiple subrequests:	642	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	643	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	644	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	645	C<begin> and for each subrequest you finish, call C<end>.
449		646
450	=back	647	=back
451		648
452	=head3 METHODS FOR CONSUMERS	649	=head3 METHODS FOR CONSUMERS
453		650
454	These methods should only be used by the consuming side, i.e. the	651	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	652	code awaits the condition.
456		653
457	=over 4	654	=over 4
458		655
459	=item $cv->wait	656	=item $cv->recv
460		657
461	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	658	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462	>> methods have been called on c<$cv>, while servicing other watchers	659	>> methods have been called on c<$cv>, while servicing other watchers
463	normally.	660	normally.
464		661
…		…
475	(programs might want to do that to stay interactive), so I<if you are	672	(programs might want to do that to stay interactive), so I<if you are
476	using this from a module, never require a blocking wait>, but let the	673	using this from a module, never require a blocking wait>, but let the
477	caller decide whether the call will block or not (for example, by coupling	674	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	675	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	676	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	677	while still supporting blocking waits if the caller so desires).
481		678
482	Another reason I<never> to C<< ->wait >> in a module is that you cannot	679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->wait >>'s in parallel, as that would require	680	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.	682	can supply.
486		683
487	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in	684	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
488	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe	685	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
489	versions and also integrates coroutines into AnyEvent, making blocking	686	versions and also integrates coroutines into AnyEvent, making blocking
490	C<< ->wait >> calls perfectly safe as long as they are done from another	687	C<< ->recv >> calls perfectly safe as long as they are done from another
491	coroutine (one that doesn't run the event loop).	688	coroutine (one that doesn't run the event loop).
492		689
493	You can ensure that C<< -wait >> never blocks by setting a callback and	690	You can ensure that C<< -recv >> never blocks by setting a callback and
494	only calling C<< ->wait >> from within that callback (or at a later	691	only calling C<< ->recv >> from within that callback (or at a later
495	time). This will work even when the event loop does not support blocking	692	time). This will work even when the event loop does not support blocking
496	waits otherwise.	693	waits otherwise.
497		694
498	=item $bool = $cv->ready	695	=item $bool = $cv->ready
499		696
500	Returns true when the condition is "true", i.e. whether C<send> or	697	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	698	C<croak> have been called.
502		699
503	=item $cb = $cv->cb ([new callback])	700	=item $cb = $cv->cb ($cb->($cv))
504		701
505	This is a mutator function that returns the callback set and optionally	702	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	703	replaces it before doing so.
507		704
508	The callback will be called when the condition becomes "true", i.e. when	705	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<wait> inside the callback	706	C<send> or C<croak> are called, with the only argument being the condition
510	or at any later time is guaranteed not to block.	707	variable itself. Calling C<recv> inside the callback or at any later time
		708	is guaranteed not to block.
511		709
512	=back	710	=back
513		711
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	712	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		713
…		…
555		753
556	Arranges for the code block to be executed as soon as the event model is	754	Arranges for the code block to be executed as soon as the event model is
557	autodetected (or immediately if this has already happened).	755	autodetected (or immediately if this has already happened).
558		756
559	If called in scalar or list context, then it creates and returns an object	757	If called in scalar or list context, then it creates and returns an object
560	that automatically removes the callback again when it is destroyed.	758	that automatically removes the callback again when it is destroyed. See
		759	L<Coro::BDB> for a case where this is useful.
561		760
562	=item @AnyEvent::post_detect	761	=item @AnyEvent::post_detect
563		762
564	If there are any code references in this array (you can C<push> to it	763	If there are any code references in this array (you can C<push> to it
565	before or after loading AnyEvent), then they will called directly after	764	before or after loading AnyEvent), then they will called directly after
…		…
581	Be careful when you create watchers in the module body - AnyEvent will	780	Be careful when you create watchers in the module body - AnyEvent will
582	decide which event module to use as soon as the first method is called, so	781	decide which event module to use as soon as the first method is called, so
583	by calling AnyEvent in your module body you force the user of your module	782	by calling AnyEvent in your module body you force the user of your module
584	to load the event module first.	783	to load the event module first.
585		784
586	Never call C<< ->wait >> on a condition variable unless you I<know> that	785	Never call C<< ->recv >> on a condition variable unless you I<know> that
587	the C<< ->send >> method has been called on it already. This is	786	the C<< ->send >> method has been called on it already. This is
588	because it will stall the whole program, and the whole point of using	787	because it will stall the whole program, and the whole point of using
589	events is to stay interactive.	788	events is to stay interactive.
590		789
591	It is fine, however, to call C<< ->wait >> when the user of your module	790	It is fine, however, to call C<< ->recv >> when the user of your module
592	requests it (i.e. if you create a http request object ad have a method	791	requests it (i.e. if you create a http request object ad have a method
593	called C<results> that returns the results, it should call C<< ->wait >>	792	called C<results> that returns the results, it should call C<< ->recv >>
594	freely, as the user of your module knows what she is doing. always).	793	freely, as the user of your module knows what she is doing. always).
595		794
596	=head1 WHAT TO DO IN THE MAIN PROGRAM	795	=head1 WHAT TO DO IN THE MAIN PROGRAM
597		796
598	There will always be a single main program - the only place that should	797	There will always be a single main program - the only place that should
…		…
600		799
601	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
602	do anything special (it does not need to be event-based) and let AnyEvent	801	do anything special (it does not need to be event-based) and let AnyEvent
603	decide which implementation to chose if some module relies on it.	802	decide which implementation to chose if some module relies on it.
604		803
605	If the main program relies on a specific event model. For example, in	804	If the main program relies on a specific event model - for example, in
606	Gtk2 programs you have to rely on the Glib module. You should load the	805	Gtk2 programs you have to rely on the Glib module - you should load the
607	event module before loading AnyEvent or any module that uses it: generally	806	event module before loading AnyEvent or any module that uses it: generally
608	speaking, you should load it as early as possible. The reason is that	807	speaking, you should load it as early as possible. The reason is that
609	modules might create watchers when they are loaded, and AnyEvent will	808	modules might create watchers when they are loaded, and AnyEvent will
610	decide on the event model to use as soon as it creates watchers, and it	809	decide on the event model to use as soon as it creates watchers, and it
611	might chose the wrong one unless you load the correct one yourself.	810	might chose the wrong one unless you load the correct one yourself.
612		811
613	You can chose to use a rather inefficient pure-perl implementation by	812	You can chose to use a pure-perl implementation by loading the
614	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
615	behaviour everywhere, but letting AnyEvent chose is generally better.	814	everywhere, but letting AnyEvent chose the model is generally better.
		815
		816	=head2 MAINLOOP EMULATION
		817
		818	Sometimes (often for short test scripts, or even standalone programs who
		819	only want to use AnyEvent), you do not want to run a specific event loop.
		820
		821	In that case, you can use a condition variable like this:
		822
		823	AnyEvent->condvar->recv;
		824
		825	This has the effect of entering the event loop and looping forever.
		826
		827	Note that usually your program has some exit condition, in which case
		828	it is better to use the "traditional" approach of storing a condition
		829	variable somewhere, waiting for it, and sending it when the program should
		830	exit cleanly.
		831
616		832
617	=head1 OTHER MODULES	833	=head1 OTHER MODULES
618		834
619	The following is a non-exhaustive list of additional modules that use	835	The following is a non-exhaustive list of additional modules that use
620	AnyEvent and can therefore be mixed easily with other AnyEvent modules	836	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
626	=item L<AnyEvent::Util>	842	=item L<AnyEvent::Util>
627		843
628	Contains various utility functions that replace often-used but blocking	844	Contains various utility functions that replace often-used but blocking
629	functions such as C<inet_aton> by event-/callback-based versions.	845	functions such as C<inet_aton> by event-/callback-based versions.
630		846
		847	=item L<AnyEvent::Socket>
		848
		849	Provides various utility functions for (internet protocol) sockets,
		850	addresses and name resolution. Also functions to create non-blocking tcp
		851	connections or tcp servers, with IPv6 and SRV record support and more.
		852
631	=item L<AnyEvent::Handle>	853	=item L<AnyEvent::Handle>
632		854
633	Provide read and write buffers and manages watchers for reads and writes.	855	Provide read and write buffers, manages watchers for reads and writes,
		856	supports raw and formatted I/O, I/O queued and fully transparent and
		857	non-blocking SSL/TLS.
634		858
635	=item L<AnyEvent::Socket>	859	=item L<AnyEvent::DNS>
636		860
637	Provides a means to do non-blocking connects, accepts etc.	861	Provides rich asynchronous DNS resolver capabilities.
		862
		863	=item L<AnyEvent::HTTP>
		864
		865	A simple-to-use HTTP library that is capable of making a lot of concurrent
		866	HTTP requests.
638		867
639	=item L<AnyEvent::HTTPD>	868	=item L<AnyEvent::HTTPD>
640		869
641	Provides a simple web application server framework.	870	Provides a simple web application server framework.
642		871
643	=item L<AnyEvent::DNS>
644
645	Provides asynchronous DNS resolver capabilities, beyond what
646	L<AnyEvent::Util> offers.
647
648	=item L<AnyEvent::FastPing>	872	=item L<AnyEvent::FastPing>
649		873
650	The fastest ping in the west.	874	The fastest ping in the west.
651		875
		876	=item L<AnyEvent::DBI>
		877
		878	Executes L<DBI> requests asynchronously in a proxy process.
		879
		880	=item L<AnyEvent::AIO>
		881
		882	Truly asynchronous I/O, should be in the toolbox of every event
		883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		884	together.
		885
		886	=item L<AnyEvent::BDB>
		887
		888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		889	L<BDB> and AnyEvent together.
		890
		891	=item L<AnyEvent::GPSD>
		892
		893	A non-blocking interface to gpsd, a daemon delivering GPS information.
		894
		895	=item L<AnyEvent::IGS>
		896
		897	A non-blocking interface to the Internet Go Server protocol (used by
		898	L<App::IGS>).
		899
652	=item L<Net::IRC3>	900	=item L<AnyEvent::IRC>
653		901
654	AnyEvent based IRC client module family.	902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
655		903
656	=item L<Net::XMPP2>	904	=item L<Net::XMPP2>
657		905
658	AnyEvent based XMPP (Jabber protocol) module family.	906	AnyEvent based XMPP (Jabber protocol) module family.
659		907
…		…
672		920
673	=item L<IO::Lambda>	921	=item L<IO::Lambda>
674		922
675	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
676		924
677	=item L<IO::AIO>
678
679	Truly asynchronous I/O, should be in the toolbox of every event
680	programmer. Can be trivially made to use AnyEvent.
681
682	=item L<BDB>
683
684	Truly asynchronous Berkeley DB access. Can be trivially made to use
685	AnyEvent.
686
687	=back	925	=back
688		926
689	=cut	927	=cut
690		928
691	package AnyEvent;	929	package AnyEvent;
692		930
693	no warnings;	931	no warnings;
694	use strict;	932	use strict qw(vars subs);
695		933
696	use Carp;	934	use Carp;
697		935
698	our $VERSION = '3.4';	936	our $VERSION = 4.411;
699	our $MODEL;	937	our $MODEL;
700		938
701	our $AUTOLOAD;	939	our $AUTOLOAD;
702	our @ISA;	940	our @ISA;
703		941
		942	our @REGISTRY;
		943
		944	our $WIN32;
		945
		946	BEGIN {
		947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		949
		950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		951	if ${^TAINT};
		952	}
		953
704	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
705		955
706	our @REGISTRY;	956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		957
		958	{
		959	my $idx;
		960	$PROTOCOL{$_} = ++$idx
		961	for reverse split /\s*,\s*/,
		962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		963	}
707		964
708	my @models = (	965	my @models = (
709	[EV:: => AnyEvent::Impl::EV::],	966	[EV:: => AnyEvent::Impl::EV::],
710	[Event:: => AnyEvent::Impl::Event::],	967	[Event:: => AnyEvent::Impl::Event::],
711	[Tk:: => AnyEvent::Impl::Tk::],
712	[Wx:: => AnyEvent::Impl::POE::],
713	[Prima:: => AnyEvent::Impl::POE::],
714	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
715	# everything below here will not be autoprobed as the pureperl backend should work everywhere	969	# everything below here will not be autoprobed
716	[Glib:: => AnyEvent::Impl::Glib::],	970	# as the pureperl backend should work everywhere
		971	# and is usually faster
		972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
717	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
718	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
719	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		977	[Wx:: => AnyEvent::Impl::POE::],
		978	[Prima:: => AnyEvent::Impl::POE::],
720	);	979	);
721		980
722	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	981	our %method = map +($_ => 1),
		982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
723		983
724	our @post_detect;	984	our @post_detect;
725		985
726	sub post_detect(&) {	986	sub post_detect(&) {
727	my ($cb) = @_;	987	my ($cb) = @_;
…		…
732	1	992	1
733	} else {	993	} else {
734	push @post_detect, $cb;	994	push @post_detect, $cb;
735		995
736	defined wantarray	996	defined wantarray
737	? bless \$cb, "AnyEvent::Util::Guard"	997	? bless \$cb, "AnyEvent::Util::postdetect"
738	: ()	998	: ()
739	}	999	}
740	}	1000	}
741		1001
742	sub AnyEvent::Util::Guard::DESTROY {	1002	sub AnyEvent::Util::postdetect::DESTROY {
743	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
744	}	1004	}
745		1005
746	sub detect() {	1006	sub detect() {
747	unless ($MODEL) {	1007	unless ($MODEL) {
748	no strict 'refs';	1008	no strict 'refs';
		1009	local $SIG{__DIE__};
749		1010
750	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
751	my $model = "AnyEvent::Impl::$1";	1012	my $model = "AnyEvent::Impl::$1";
752	if (eval "require $model") {	1013	if (eval "require $model") {
753	$MODEL = $model;	1014	$MODEL = $model;
…		…
783	last;	1044	last;
784	}	1045	}
785	}	1046	}
786		1047
787	$MODEL	1048	$MODEL
788	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
789	}	1050	}
790	}	1051	}
791		1052
		1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1054
792	unshift @ISA, $MODEL;	1055	unshift @ISA, $MODEL;
793	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1056
		1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
794		1058
795	(shift @post_detect)->() while @post_detect;	1059	(shift @post_detect)->() while @post_detect;
796	}	1060	}
797		1061
798	$MODEL	1062	$MODEL
…		…
808		1072
809	my $class = shift;	1073	my $class = shift;
810	$class->$func (@_);	1074	$class->$func (@_);
811	}	1075	}
812		1076
		1077	# utility function to dup a filehandle. this is used by many backends
		1078	# to support binding more than one watcher per filehandle (they usually
		1079	# allow only one watcher per fd, so we dup it to get a different one).
		1080	sub _dupfh($$$$) {
		1081	my ($poll, $fh, $r, $w) = @_;
		1082
		1083	# cygwin requires the fh mode to be matching, unix doesn't
		1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1085	: $poll eq "w" ? ($w, ">")
		1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1087
		1088	open my $fh2, "$mode&" . fileno $fh
		1089	or die "cannot dup() filehandle: $!,";
		1090
		1091	# we assume CLOEXEC is already set by perl in all important cases
		1092
		1093	($fh2, $rw)
		1094	}
		1095
813	package AnyEvent::Base;	1096	package AnyEvent::Base;
814		1097
		1098	# default implementations for many methods
		1099
		1100	BEGIN {
		1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1102	*_time = \&Time::HiRes::time;
		1103	# if (eval "use POSIX (); (POSIX::times())...
		1104	} else {
		1105	*_time = sub { time }; # epic fail
		1106	}
		1107	}
		1108
		1109	sub time { _time }
		1110	sub now { _time }
		1111	sub now_update { }
		1112
815	# default implementation for ->condvar, ->wait, ->broadcast	1113	# default implementation for ->condvar
816		1114
817	sub condvar {	1115	sub condvar {
818	bless \my $flag, "AnyEvent::Base::CondVar"	1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
819	}
820
821	sub AnyEvent::Base::CondVar::broadcast {
822	${$_[0]}++;
823	}
824
825	sub AnyEvent::Base::CondVar::wait {
826	AnyEvent->one_event while !${$_[0]};
827	}	1117	}
828		1118
829	# default implementation for ->signal	1119	# default implementation for ->signal
830		1120
831	our %SIG_CB;	1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1122
		1123	sub _signal_exec {
		1124	sysread $SIGPIPE_R, my $dummy, 4;
		1125
		1126	while (%SIG_EV) {
		1127	for (keys %SIG_EV) {
		1128	delete $SIG_EV{$_};
		1129	$_->() for values %{ $SIG_CB{$_} || {} };
		1130	}
		1131	}
		1132	}
832		1133
833	sub signal {	1134	sub signal {
834	my (undef, %arg) = @_;	1135	my (undef, %arg) = @_;
835		1136
		1137	unless ($SIGPIPE_R) {
		1138	require Fcntl;
		1139
		1140	if (AnyEvent::WIN32) {
		1141	require AnyEvent::Util;
		1142
		1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1146	} else {
		1147	pipe $SIGPIPE_R, $SIGPIPE_W;
		1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154	}
		1155
		1156	$SIGPIPE_R
		1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1158
		1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1160	}
		1161
836	my $signal = uc $arg{signal}	1162	my $signal = uc $arg{signal}
837	or Carp::croak "required option 'signal' is missing";	1163	or Carp::croak "required option 'signal' is missing";
838		1164
839	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
840	$SIG{$signal} ||= sub {	1166	$SIG{$signal} ||= sub {
841	$_->() for values %{ $SIG_CB{$signal} || {} };	1167	local $!;
		1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1169	undef $SIG_EV{$signal};
842	};	1170	};
843		1171
844	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
845	}	1173	}
846		1174
847	sub AnyEvent::Base::Signal::DESTROY {	1175	sub AnyEvent::Base::signal::DESTROY {
848	my ($signal, $cb) = @{$_[0]};	1176	my ($signal, $cb) = @{$_[0]};
849		1177
850	delete $SIG_CB{$signal}{$cb};	1178	delete $SIG_CB{$signal}{$cb};
851		1179
		1180	# delete doesn't work with older perls - they then
		1181	# print weird messages, or just unconditionally exit
		1182	# instead of getting the default action.
852	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
853	}	1184	}
854		1185
855	# default implementation for ->child	1186	# default implementation for ->child
856		1187
857	our %PID_CB;	1188	our %PID_CB;
858	our $CHLD_W;	1189	our $CHLD_W;
859	our $CHLD_DELAY_W;	1190	our $CHLD_DELAY_W;
860	our $PID_IDLE;
861	our $WNOHANG;	1191	our $WNOHANG;
862		1192
863	sub _child_wait {	1193	sub _sigchld {
864	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
865	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
866	(values %{ $PID_CB{0} || {} });	1196	(values %{ $PID_CB{0} || {} });
867	}	1197	}
868
869	undef $PID_IDLE;
870	}
871
872	sub _sigchld {
873	# make sure we deliver these changes "synchronous" with the event loop.
874	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
875	undef $CHLD_DELAY_W;
876	&_child_wait;
877	});
878	}	1198	}
879		1199
880	sub child {	1200	sub child {
881	my (undef, %arg) = @_;	1201	my (undef, %arg) = @_;
882		1202
883	defined (my $pid = $arg{pid} + 0)	1203	defined (my $pid = $arg{pid} + 0)
884	or Carp::croak "required option 'pid' is missing";	1204	or Carp::croak "required option 'pid' is missing";
885		1205
886	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
887		1207
888	unless ($WNOHANG) {
889	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
890	}
891		1209
892	unless ($CHLD_W) {	1210	unless ($CHLD_W) {
893	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
894	# child could be a zombie already, so make at least one round	1212	# child could be a zombie already, so make at least one round
895	&_sigchld;	1213	&_sigchld;
896	}	1214	}
897		1215
898	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
899	}	1217	}
900		1218
901	sub AnyEvent::Base::Child::DESTROY {	1219	sub AnyEvent::Base::child::DESTROY {
902	my ($pid, $cb) = @{$_[0]};	1220	my ($pid, $cb) = @{$_[0]};
903		1221
904	delete $PID_CB{$pid}{$cb};	1222	delete $PID_CB{$pid}{$cb};
905	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
906		1224
907	undef $CHLD_W unless keys %PID_CB;	1225	undef $CHLD_W unless keys %PID_CB;
908	}	1226	}
		1227
		1228	# idle emulation is done by simply using a timer, regardless
		1229	# of whether the process is idle or not, and not letting
		1230	# the callback use more than 50% of the time.
		1231	sub idle {
		1232	my (undef, %arg) = @_;
		1233
		1234	my ($cb, $w, $rcb) = $arg{cb};
		1235
		1236	$rcb = sub {
		1237	if ($cb) {
		1238	$w = _time;
		1239	&$cb;
		1240	$w = _time - $w;
		1241
		1242	# never use more then 50% of the time for the idle watcher,
		1243	# within some limits
		1244	$w = 0.0001 if $w < 0.0001;
		1245	$w = 5 if $w > 5;
		1246
		1247	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1248	} else {
		1249	# clean up...
		1250	undef $w;
		1251	undef $rcb;
		1252	}
		1253	};
		1254
		1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1256
		1257	bless \\$cb, "AnyEvent::Base::idle"
		1258	}
		1259
		1260	sub AnyEvent::Base::idle::DESTROY {
		1261	undef $${$_[0]};
		1262	}
		1263
		1264	package AnyEvent::CondVar;
		1265
		1266	our @ISA = AnyEvent::CondVar::Base::;
		1267
		1268	package AnyEvent::CondVar::Base;
		1269
		1270	use overload
		1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1272	fallback => 1;
		1273
		1274	sub _send {
		1275	# nop
		1276	}
		1277
		1278	sub send {
		1279	my $cv = shift;
		1280	$cv->{_ae_sent} = [@_];
		1281	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1282	$cv->_send;
		1283	}
		1284
		1285	sub croak {
		1286	$_[0]{_ae_croak} = $_[1];
		1287	$_[0]->send;
		1288	}
		1289
		1290	sub ready {
		1291	$_[0]{_ae_sent}
		1292	}
		1293
		1294	sub _wait {
		1295	AnyEvent->one_event while !$_[0]{_ae_sent};
		1296	}
		1297
		1298	sub recv {
		1299	$_[0]->_wait;
		1300
		1301	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1302	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1303	}
		1304
		1305	sub cb {
		1306	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1307	$_[0]{_ae_cb}
		1308	}
		1309
		1310	sub begin {
		1311	++$_[0]{_ae_counter};
		1312	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1313	}
		1314
		1315	sub end {
		1316	return if --$_[0]{_ae_counter};
		1317	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1318	}
		1319
		1320	# undocumented/compatibility with pre-3.4
		1321	*broadcast = \&send;
		1322	*wait = \&_wait;
		1323
		1324	=head1 ERROR AND EXCEPTION HANDLING
		1325
		1326	In general, AnyEvent does not do any error handling - it relies on the
		1327	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1328	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1329	checking of all AnyEvent methods, however, which is highly useful during
		1330	development.
		1331
		1332	As for exception handling (i.e. runtime errors and exceptions thrown while
		1333	executing a callback), this is not only highly event-loop specific, but
		1334	also not in any way wrapped by this module, as this is the job of the main
		1335	program.
		1336
		1337	The pure perl event loop simply re-throws the exception (usually
		1338	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1340	so on.
		1341
		1342	=head1 ENVIRONMENT VARIABLES
		1343
		1344	The following environment variables are used by this module or its
		1345	submodules.
		1346
		1347	Note that AnyEvent will remove I<all> environment variables starting with
		1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1349	enabled.
		1350
		1351	=over 4
		1352
		1353	=item C<PERL_ANYEVENT_VERBOSE>
		1354
		1355	By default, AnyEvent will be completely silent except in fatal
		1356	conditions. You can set this environment variable to make AnyEvent more
		1357	talkative.
		1358
		1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1360	conditions, such as not being able to load the event model specified by
		1361	C<PERL_ANYEVENT_MODEL>.
		1362
		1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1364	model it chooses.
		1365
		1366	=item C<PERL_ANYEVENT_STRICT>
		1367
		1368	AnyEvent does not do much argument checking by default, as thorough
		1369	argument checking is very costly. Setting this variable to a true value
		1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1371	check the arguments passed to most method calls. If it finds any problems
		1372	it will croak.
		1373
		1374	In other words, enables "strict" mode.
		1375
		1376	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1378	developing programs can be very useful, however.
		1379
		1380	=item C<PERL_ANYEVENT_MODEL>
		1381
		1382	This can be used to specify the event model to be used by AnyEvent, before
		1383	auto detection and -probing kicks in. It must be a string consisting
		1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1385	and the resulting module name is loaded and if the load was successful,
		1386	used as event model. If it fails to load AnyEvent will proceed with
		1387	auto detection and -probing.
		1388
		1389	This functionality might change in future versions.
		1390
		1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1392	could start your program like this:
		1393
		1394	PERL_ANYEVENT_MODEL=Perl perl ...
		1395
		1396	=item C<PERL_ANYEVENT_PROTOCOLS>
		1397
		1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1400	of auto probing).
		1401
		1402	Must be set to a comma-separated list of protocols or address families,
		1403	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1404	used, and preference will be given to protocols mentioned earlier in the
		1405	list.
		1406
		1407	This variable can effectively be used for denial-of-service attacks
		1408	against local programs (e.g. when setuid), although the impact is likely
		1409	small, as the program has to handle conenction and other failures anyways.
		1410
		1411	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1413	- only support IPv4, never try to resolve or contact IPv6
		1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1415	IPv6, but prefer IPv6 over IPv4.
		1416
		1417	=item C<PERL_ANYEVENT_EDNS0>
		1418
		1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1420	for DNS. This extension is generally useful to reduce DNS traffic, but
		1421	some (broken) firewalls drop such DNS packets, which is why it is off by
		1422	default.
		1423
		1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1425	EDNS0 in its DNS requests.
		1426
		1427	=item C<PERL_ANYEVENT_MAX_FORKS>
		1428
		1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1430	will create in parallel.
		1431
		1432	=back
909		1433
910	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
911		1435
912	This is an advanced topic that you do not normally need to use AnyEvent in	1436	This is an advanced topic that you do not normally need to use AnyEvent in
913	a module. This section is only of use to event loop authors who want to	1437	a module. This section is only of use to event loop authors who want to
…		…
947		1471
948	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1472	I<rxvt-unicode> also cheats a bit by not providing blocking access to
949	condition variables: code blocking while waiting for a condition will	1473	condition variables: code blocking while waiting for a condition will
950	C<die>. This still works with most modules/usages, and blocking calls must	1474	C<die>. This still works with most modules/usages, and blocking calls must
951	not be done in an interactive application, so it makes sense.	1475	not be done in an interactive application, so it makes sense.
952
953	=head1 ENVIRONMENT VARIABLES
954
955	The following environment variables are used by this module:
956
957	=over 4
958
959	=item C<PERL_ANYEVENT_VERBOSE>
960
961	By default, AnyEvent will be completely silent except in fatal
962	conditions. You can set this environment variable to make AnyEvent more
963	talkative.
964
965	When set to C<1> or higher, causes AnyEvent to warn about unexpected
966	conditions, such as not being able to load the event model specified by
967	C<PERL_ANYEVENT_MODEL>.
968
969	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
970	model it chooses.
971
972	=item C<PERL_ANYEVENT_MODEL>
973
974	This can be used to specify the event model to be used by AnyEvent, before
975	autodetection and -probing kicks in. It must be a string consisting
976	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
977	and the resulting module name is loaded and if the load was successful,
978	used as event model. If it fails to load AnyEvent will proceed with
979	autodetection and -probing.
980
981	This functionality might change in future versions.
982
983	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
984	could start your program like this:
985
986	PERL_ANYEVENT_MODEL=Perl perl ...
987
988	=back
989		1476
990	=head1 EXAMPLE PROGRAM	1477	=head1 EXAMPLE PROGRAM
991		1478
992	The following program uses an I/O watcher to read data from STDIN, a timer	1479	The following program uses an I/O watcher to read data from STDIN, a timer
993	to display a message once per second, and a condition variable to quit the	1480	to display a message once per second, and a condition variable to quit the
…		…
1002	poll => 'r',	1489	poll => 'r',
1003	cb => sub {	1490	cb => sub {
1004	warn "io event <$_[0]>\n"; # will always output <r>	1491	warn "io event <$_[0]>\n"; # will always output <r>
1005	chomp (my $input = <STDIN>); # read a line	1492	chomp (my $input = <STDIN>); # read a line
1006	warn "read: $input\n"; # output what has been read	1493	warn "read: $input\n"; # output what has been read
1007	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1494	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1008	},	1495	},
1009	);	1496	);
1010		1497
1011	my $time_watcher; # can only be used once	1498	my $time_watcher; # can only be used once
1012		1499
…		…
1017	});	1504	});
1018	}	1505	}
1019		1506
1020	new_timer; # create first timer	1507	new_timer; # create first timer
1021		1508
1022	$cv->wait; # wait until user enters /^q/i	1509	$cv->recv; # wait until user enters /^q/i
1023		1510
1024	=head1 REAL-WORLD EXAMPLE	1511	=head1 REAL-WORLD EXAMPLE
1025		1512
1026	Consider the L<Net::FCP> module. It features (among others) the following	1513	Consider the L<Net::FCP> module. It features (among others) the following
1027	API calls, which are to freenet what HTTP GET requests are to http:	1514	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1077	syswrite $txn->{fh}, $txn->{request}	1564	syswrite $txn->{fh}, $txn->{request}
1078	or die "connection or write error";	1565	or die "connection or write error";
1079	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1566	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1080		1567
1081	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1568	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1082	result and signals any possible waiters that the request ahs finished:	1569	result and signals any possible waiters that the request has finished:
1083		1570
1084	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1571	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1085		1572
1086	if (end-of-file or data complete) {	1573	if (end-of-file or data complete) {
1087	$txn->{result} = $txn->{buf};	1574	$txn->{result} = $txn->{buf};
1088	$txn->{finished}->broadcast;	1575	$txn->{finished}->send;
1089	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1576	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1090	}	1577	}
1091		1578
1092	The C<result> method, finally, just waits for the finished signal (if the	1579	The C<result> method, finally, just waits for the finished signal (if the
1093	request was already finished, it doesn't wait, of course, and returns the	1580	request was already finished, it doesn't wait, of course, and returns the
1094	data:	1581	data:
1095		1582
1096	$txn->{finished}->wait;	1583	$txn->{finished}->recv;
1097	return $txn->{result};	1584	return $txn->{result};
1098		1585
1099	The actual code goes further and collects all errors (C<die>s, exceptions)	1586	The actual code goes further and collects all errors (C<die>s, exceptions)
1100	that occured during request processing. The C<result> method detects	1587	that occurred during request processing. The C<result> method detects
1101	whether an exception as thrown (it is stored inside the $txn object)	1588	whether an exception as thrown (it is stored inside the $txn object)
1102	and just throws the exception, which means connection errors and other	1589	and just throws the exception, which means connection errors and other
1103	problems get reported tot he code that tries to use the result, not in a	1590	problems get reported tot he code that tries to use the result, not in a
1104	random callback.	1591	random callback.
1105		1592
…		…
1136		1623
1137	my $quit = AnyEvent->condvar;	1624	my $quit = AnyEvent->condvar;
1138		1625
1139	$fcp->txn_client_get ($url)->cb (sub {	1626	$fcp->txn_client_get ($url)->cb (sub {
1140	...	1627	...
1141	$quit->broadcast;	1628	$quit->send;
1142	});	1629	});
1143		1630
1144	$quit->wait;	1631	$quit->recv;
1145		1632
1146		1633
1147	=head1 BENCHMARKS	1634	=head1 BENCHMARKS
1148		1635
1149	To give you an idea of the performance and overheads that AnyEvent adds	1636	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1151	of various event loops I prepared some benchmarks.	1638	of various event loops I prepared some benchmarks.
1152		1639
1153	=head2 BENCHMARKING ANYEVENT OVERHEAD	1640	=head2 BENCHMARKING ANYEVENT OVERHEAD
1154		1641
1155	Here is a benchmark of various supported event models used natively and	1642	Here is a benchmark of various supported event models used natively and
1156	through anyevent. The benchmark creates a lot of timers (with a zero	1643	through AnyEvent. The benchmark creates a lot of timers (with a zero
1157	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1158	which it is), lets them fire exactly once and destroys them again.	1645	which it is), lets them fire exactly once and destroys them again.
1159		1646
1160	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1161	distribution.	1648	distribution.
…		…
1178	all watchers, to avoid adding memory overhead. That means closure creation	1665	all watchers, to avoid adding memory overhead. That means closure creation
1179	and memory usage is not included in the figures.	1666	and memory usage is not included in the figures.
1180		1667
1181	I<invoke> is the time, in microseconds, used to invoke a simple	1668	I<invoke> is the time, in microseconds, used to invoke a simple
1182	callback. The callback simply counts down a Perl variable and after it was	1669	callback. The callback simply counts down a Perl variable and after it was
1183	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1670	invoked "watcher" times, it would C<< ->send >> a condvar once to
1184	signal the end of this phase.	1671	signal the end of this phase.
1185		1672
1186	I<destroy> is the time, in microseconds, that it takes to destroy a single	1673	I<destroy> is the time, in microseconds, that it takes to destroy a single
1187	watcher.	1674	watcher.
1188		1675
1189	=head3 Results	1676	=head3 Results
1190		1677
1191	name watchers bytes create invoke destroy comment	1678	name watchers bytes create invoke destroy comment
1192	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1193	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1194	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1195	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1196	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1197	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1198	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1199	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1200	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1201	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1202		1689
1203	=head3 Discussion	1690	=head3 Discussion
1204		1691
1205	The benchmark does I<not> measure scalability of the event loop very	1692	The benchmark does I<not> measure scalability of the event loop very
1206	well. For example, a select-based event loop (such as the pure perl one)	1693	well. For example, a select-based event loop (such as the pure perl one)
…		…
1284		1771
1285	=back	1772	=back
1286		1773
1287	=head2 BENCHMARKING THE LARGE SERVER CASE	1774	=head2 BENCHMARKING THE LARGE SERVER CASE
1288		1775
1289	This benchmark atcually benchmarks the event loop itself. It works by	1776	This benchmark actually benchmarks the event loop itself. It works by
1290	creating a number of "servers": each server consists of a socketpair, a	1777	creating a number of "servers": each server consists of a socket pair, a
1291	timeout watcher that gets reset on activity (but never fires), and an I/O	1778	timeout watcher that gets reset on activity (but never fires), and an I/O
1292	watcher waiting for input on one side of the socket. Each time the socket	1779	watcher waiting for input on one side of the socket. Each time the socket
1293	watcher reads a byte it will write that byte to a random other "server".	1780	watcher reads a byte it will write that byte to a random other "server".
1294		1781
1295	The effect is that there will be a lot of I/O watchers, only part of which	1782	The effect is that there will be a lot of I/O watchers, only part of which
1296	are active at any one point (so there is a constant number of active	1783	are active at any one point (so there is a constant number of active
1297	fds for each loop iterstaion, but which fds these are is random). The	1784	fds for each loop iteration, but which fds these are is random). The
1298	timeout is reset each time something is read because that reflects how	1785	timeout is reset each time something is read because that reflects how
1299	most timeouts work (and puts extra pressure on the event loops).	1786	most timeouts work (and puts extra pressure on the event loops).
1300		1787
1301	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1302	(1%) are active. This mirrors the activity of large servers with many	1789	(1%) are active. This mirrors the activity of large servers with many
1303	connections, most of which are idle at any one point in time.	1790	connections, most of which are idle at any one point in time.
1304		1791
1305	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1306	distribution.	1793	distribution.
…		…
1308	=head3 Explanation of the columns	1795	=head3 Explanation of the columns
1309		1796
1310	I<sockets> is the number of sockets, and twice the number of "servers" (as	1797	I<sockets> is the number of sockets, and twice the number of "servers" (as
1311	each server has a read and write socket end).	1798	each server has a read and write socket end).
1312		1799
1313	I<create> is the time it takes to create a socketpair (which is	1800	I<create> is the time it takes to create a socket pair (which is
1314	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1801	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1315		1802
1316	I<request>, the most important value, is the time it takes to handle a	1803	I<request>, the most important value, is the time it takes to handle a
1317	single "request", that is, reading the token from the pipe and forwarding	1804	single "request", that is, reading the token from the pipe and forwarding
1318	it to another server. This includes deleting the old timeout and creating	1805	it to another server. This includes deleting the old timeout and creating
…		…
1391	speed most when you have lots of watchers, not when you only have a few of	1878	speed most when you have lots of watchers, not when you only have a few of
1392	them).	1879	them).
1393		1880
1394	EV is again fastest.	1881	EV is again fastest.
1395		1882
1396	Perl again comes second. It is noticably faster than the C-based event	1883	Perl again comes second. It is noticeably faster than the C-based event
1397	loops Event and Glib, although the difference is too small to really	1884	loops Event and Glib, although the difference is too small to really
1398	matter.	1885	matter.
1399		1886
1400	POE also performs much better in this case, but is is still far behind the	1887	POE also performs much better in this case, but is is still far behind the
1401	others.	1888	others.
…		…
1406		1893
1407	=item * C-based event loops perform very well with small number of	1894	=item * C-based event loops perform very well with small number of
1408	watchers, as the management overhead dominates.	1895	watchers, as the management overhead dominates.
1409		1896
1410	=back	1897	=back
		1898
		1899	=head2 THE IO::Lambda BENCHMARK
		1900
		1901	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1902	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1903	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1904	shouldn't come as a surprise to anybody). As such, the benchmark is
		1905	fine, and shows that the AnyEvent backend from IO::Lambda isn't very
		1906	optimal. But how would AnyEvent compare when used without the extra
		1907	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1908
		1909	The benchmark itself creates an echo-server, and then, for 500 times,
		1910	connects to the echo server, sends a line, waits for the reply, and then
		1911	creates the next connection. This is a rather bad benchmark, as it doesn't
		1912	test the efficiency of the framework, but it is a benchmark nevertheless.
		1913
		1914	name runtime
		1915	Lambda/select 0.330 sec
		1916	+ optimized 0.122 sec
		1917	Lambda/AnyEvent 0.327 sec
		1918	+ optimized 0.138 sec
		1919	Raw sockets/select 0.077 sec
		1920	POE/select, components 0.662 sec
		1921	POE/select, raw sockets 0.226 sec
		1922	POE/select, optimized 0.404 sec
		1923
		1924	AnyEvent/select/nb 0.085 sec
		1925	AnyEvent/EV/nb 0.068 sec
		1926	+state machine 0.134 sec
		1927
		1928	The benchmark is also a bit unfair (my fault) - the IO::Lambda
		1929	benchmarks actually make blocking connects and use 100% blocking I/O,
		1930	defeating the purpose of an event-based solution. All of the newly
		1931	written AnyEvent benchmarks use 100% non-blocking connects (using
		1932	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1933	resolver), so AnyEvent is at a disadvantage here as non-blocking connects
		1934	generally require a lot more bookkeeping and event handling than blocking
		1935	connects (which involve a single syscall only).
		1936
		1937	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1938	offers similar expressive power as POE and IO::Lambda (using conventional
		1939	Perl syntax), which means both the echo server and the client are 100%
		1940	non-blocking w.r.t. I/O, further placing it at a disadvantage.
		1941
		1942	As you can see, AnyEvent + EV even beats the hand-optimised "raw sockets
		1943	benchmark", while AnyEvent + its pure perl backend easily beats
		1944	IO::Lambda and POE.
		1945
		1946	And even the 100% non-blocking version written using the high-level (and
		1947	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda,
		1948	even thought it does all of DNS, tcp-connect and socket I/O in a
		1949	non-blocking way.
		1950
		1951
		1952	=head1 SIGNALS
		1953
		1954	AnyEvent currently installs handlers for these signals:
		1955
		1956	=over 4
		1957
		1958	=item SIGCHLD
		1959
		1960	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1961	emulation for event loops that do not support them natively. Also, some
		1962	event loops install a similar handler.
		1963
		1964	=item SIGPIPE
		1965
		1966	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1967	when AnyEvent gets loaded.
		1968
		1969	The rationale for this is that AnyEvent users usually do not really depend
		1970	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1971	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1972	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1973	some random socket.
		1974
		1975	The rationale for installing a no-op handler as opposed to ignoring it is
		1976	that this way, the handler will be restored to defaults on exec.
		1977
		1978	Feel free to install your own handler, or reset it to defaults.
		1979
		1980	=back
		1981
		1982	=cut
		1983
		1984	$SIG{PIPE} = sub { }
		1985	unless defined $SIG{PIPE};
1411		1986
1412		1987
1413	=head1 FORK	1988	=head1 FORK
1414		1989
1415	Most event libraries are not fork-safe. The ones who are usually are	1990	Most event libraries are not fork-safe. The ones who are usually are
…		…
1430	specified in the variable.	2005	specified in the variable.
1431		2006
1432	You can make AnyEvent completely ignore this variable by deleting it	2007	You can make AnyEvent completely ignore this variable by deleting it
1433	before the first watcher gets created, e.g. with a C<BEGIN> block:	2008	before the first watcher gets created, e.g. with a C<BEGIN> block:
1434		2009
1435	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2010	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1436		2011
1437	use AnyEvent;	2012	use AnyEvent;
1438		2013
1439	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2014	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1440	be used to probe what backend is used and gain other information (which is	2015	be used to probe what backend is used and gain other information (which is
1441	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2016	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2017	$ENV{PERL_ANYEVENT_STRICT}.
		2018
		2019
		2020	=head1 BUGS
		2021
		2022	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2023	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2024	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2025	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2026	pronounced).
1442		2027
1443		2028
1444	=head1 SEE ALSO	2029	=head1 SEE ALSO
		2030
		2031	Utility functions: L<AnyEvent::Util>.
1445		2032
1446	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2033	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1447	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2034	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1448		2035
1449	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2036	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1450	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2037	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1451	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2038	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1452	L<AnyEvent::Impl::POE>.	2039	L<AnyEvent::Impl::POE>.
1453		2040
		2041	Non-blocking file handles, sockets, TCP clients and
		2042	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		2043
		2044	Asynchronous DNS: L<AnyEvent::DNS>.
		2045
1454	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2046	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1455		2047
1456	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2048	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1457		2049
1458		2050
1459	=head1 AUTHOR	2051	=head1 AUTHOR
1460		2052
1461	Marc Lehmann <schmorp@schmorp.de>	2053	Marc Lehmann <schmorp@schmorp.de>
1462	http://home.schmorp.de/	2054	http://home.schmorp.de/
1463		2055
1464	=cut	2056	=cut
1465		2057
1466	1	2058	1
1467		2059

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