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Revision 1.226 by root, Mon Jul 6 23:32:49 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
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		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
272	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
275		403
276	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
279		408
280	Example: fork a process and wait for it	409	Example: fork a process and wait for it
281		410
282	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
283		412
284	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
285		414
286	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
287	pid => $pid,	416	pid => $pid,
288	cb => sub {	417	cb => sub {
289	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
291	$done->send;	420	$done->send;
292	},	421	},
293	);	422	);
294		423
295	# do something else, then wait for process exit	424	# do something else, then wait for process exit
296	$done->recv;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
297		461
298	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
299		463
300	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
…		…
307	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	472	because they represent a condition that must become true.
309		473
310	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
312	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
314		480
315	After creation, the conditon variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method.	482	by calling the C<send> method (or calling the condition variable as if it
		483	were a callback, read about the caveats in the description for the C<<
		484	->send >> method).
317		485
318	Condition variables are similar to callbacks, except that you can	486	Condition variables are similar to callbacks, except that you can
319	optionally wait for them. They can also be called merge points - points	487	optionally wait for them. They can also be called merge points - points
320	in time where multiple outstandign events have been processed. And yet	488	in time where multiple outstanding events have been processed. And yet
321	another way to call them is transations - each condition variable can be	489	another way to call them is transactions - each condition variable can be
322	used to represent a transaction, which finishes at some point and delivers	490	used to represent a transaction, which finishes at some point and delivers
323	a result.	491	a result.
324		492
325	Condition variables are very useful to signal that something has finished,	493	Condition variables are very useful to signal that something has finished,
326	for example, if you write a module that does asynchronous http requests,	494	for example, if you write a module that does asynchronous http requests,
…		…
332	you can block your main program until an event occurs - for example, you	500	you can block your main program until an event occurs - for example, you
333	could C<< ->recv >> in your main program until the user clicks the Quit	501	could C<< ->recv >> in your main program until the user clicks the Quit
334	button of your app, which would C<< ->send >> the "quit" event.	502	button of your app, which would C<< ->send >> the "quit" event.
335		503
336	Note that condition variables recurse into the event loop - if you have	504	Note that condition variables recurse into the event loop - if you have
337	two pieces of code that call C<< ->recv >> in a round-robbin fashion, you	505	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338	lose. Therefore, condition variables are good to export to your caller, but	506	lose. Therefore, condition variables are good to export to your caller, but
339	you should avoid making a blocking wait yourself, at least in callbacks,	507	you should avoid making a blocking wait yourself, at least in callbacks,
340	as this asks for trouble.	508	as this asks for trouble.
341		509
342	Condition variables are represented by hash refs in perl, and the keys	510	Condition variables are represented by hash refs in perl, and the keys
…		…
347		515
348	There are two "sides" to a condition variable - the "producer side" which	516	There are two "sides" to a condition variable - the "producer side" which
349	eventually calls C<< -> send >>, and the "consumer side", which waits	517	eventually calls C<< -> send >>, and the "consumer side", which waits
350	for the send to occur.	518	for the send to occur.
351		519
352	Example:	520	Example: wait for a timer.
353		521
354	# wait till the result is ready	522	# wait till the result is ready
355	my $result_ready = AnyEvent->condvar;	523	my $result_ready = AnyEvent->condvar;
356		524
357	# do something such as adding a timer	525	# do something such as adding a timer
…		…
365		533
366	# this "blocks" (while handling events) till the callback	534	# this "blocks" (while handling events) till the callback
367	# calls send	535	# calls send
368	$result_ready->recv;	536	$result_ready->recv;
369		537
		538	Example: wait for a timer, but take advantage of the fact that
		539	condition variables are also code references.
		540
		541	my $done = AnyEvent->condvar;
		542	my $delay = AnyEvent->timer (after => 5, cb => $done);
		543	$done->recv;
		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
370	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
371		563
372	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
373	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
374	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
386	immediately from within send.	578	immediately from within send.
387		579
388	Any arguments passed to the C<send> call will be returned by all	580	Any arguments passed to the C<send> call will be returned by all
389	future C<< ->recv >> calls.	581	future C<< ->recv >> calls.
390		582
		583	Condition variables are overloaded so one can call them directly
		584	(as a code reference). Calling them directly is the same as calling
		585	C<send>. Note, however, that many C-based event loops do not handle
		586	overloading, so as tempting as it may be, passing a condition variable
		587	instead of a callback does not work. Both the pure perl and EV loops
		588	support overloading, however, as well as all functions that use perl to
		589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		590	example).
		591
391	=item $cv->croak ($error)	592	=item $cv->croak ($error)
392		593
393	Similar to send, but causes all call's to C<< ->recv >> to invoke	594	Similar to send, but causes all call's to C<< ->recv >> to invoke
394	C<Carp::croak> with the given error message/object/scalar.	595	C<Carp::croak> with the given error message/object/scalar.
395		596
…		…
397	user/consumer.	598	user/consumer.
398		599
399	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
400		601
401	=item $cv->end	602	=item $cv->end
402
403	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		603
405	These two methods can be used to combine many transactions/events into	604	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	605	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
408		607
…		…
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
414		613
415	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
416		645
417	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
418		647
419	my %result;	648	my %result;
420	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
440	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
442	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	672	doesn't execute once).
444		673
445	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
447	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
448	C<begin> and for eahc subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
449		679
450	=back	680	=back
451		681
452	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
453		683
…		…
475	(programs might want to do that to stay interactive), so I<if you are	705	(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	706	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	707	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	708	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	709	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	710	while still supporting blocking waits if the caller so desires).
481		711
482	Another reason I<never> to C<< ->recv >> in a module is that you cannot	712	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->recv >>'s in parallel, as that would require	713	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	714	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.	715	can supply.
…		…
498	=item $bool = $cv->ready	728	=item $bool = $cv->ready
499		729
500	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	731	C<croak> have been called.
502		732
503	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
504		734
505	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	736	replaces it before doing so.
507		737
508	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<recv> inside the callback	739	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.	740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
511		742
512	=back	743	=back
513		744
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	745	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		746
…		…
532	AnyEvent::Impl::Tk based on Tk, very bad choice.	763	AnyEvent::Impl::Tk based on Tk, very bad choice.
533	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
534	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
535	AnyEvent::Impl::POE based on POE, not generic enough for full support.	766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
536		767
		768	# warning, support for IO::Async is only partial, as it is too broken
		769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		771
537	There is no support for WxWidgets, as WxWidgets has no support for	772	There is no support for WxWidgets, as WxWidgets has no support for
538	watching file handles. However, you can use WxWidgets through the	773	watching file handles. However, you can use WxWidgets through the
539	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
540	second, which was considered to be too horrible to even consider for	775	second, which was considered to be too horrible to even consider for
541	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
601		836
602	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	837	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
603	do anything special (it does not need to be event-based) and let AnyEvent	838	do anything special (it does not need to be event-based) and let AnyEvent
604	decide which implementation to chose if some module relies on it.	839	decide which implementation to chose if some module relies on it.
605		840
606	If the main program relies on a specific event model. For example, in	841	If the main program relies on a specific event model - for example, in
607	Gtk2 programs you have to rely on the Glib module. You should load the	842	Gtk2 programs you have to rely on the Glib module - you should load the
608	event module before loading AnyEvent or any module that uses it: generally	843	event module before loading AnyEvent or any module that uses it: generally
609	speaking, you should load it as early as possible. The reason is that	844	speaking, you should load it as early as possible. The reason is that
610	modules might create watchers when they are loaded, and AnyEvent will	845	modules might create watchers when they are loaded, and AnyEvent will
611	decide on the event model to use as soon as it creates watchers, and it	846	decide on the event model to use as soon as it creates watchers, and it
612	might chose the wrong one unless you load the correct one yourself.	847	might chose the wrong one unless you load the correct one yourself.
613		848
614	You can chose to use a rather inefficient pure-perl implementation by	849	You can chose to use a pure-perl implementation by loading the
615	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	850	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616	behaviour everywhere, but letting AnyEvent chose is generally better.	851	everywhere, but letting AnyEvent chose the model is generally better.
		852
		853	=head2 MAINLOOP EMULATION
		854
		855	Sometimes (often for short test scripts, or even standalone programs who
		856	only want to use AnyEvent), you do not want to run a specific event loop.
		857
		858	In that case, you can use a condition variable like this:
		859
		860	AnyEvent->condvar->recv;
		861
		862	This has the effect of entering the event loop and looping forever.
		863
		864	Note that usually your program has some exit condition, in which case
		865	it is better to use the "traditional" approach of storing a condition
		866	variable somewhere, waiting for it, and sending it when the program should
		867	exit cleanly.
		868
617		869
618	=head1 OTHER MODULES	870	=head1 OTHER MODULES
619		871
620	The following is a non-exhaustive list of additional modules that use	872	The following is a non-exhaustive list of additional modules that use
621	AnyEvent and can therefore be mixed easily with other AnyEvent modules	873	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
627	=item L<AnyEvent::Util>	879	=item L<AnyEvent::Util>
628		880
629	Contains various utility functions that replace often-used but blocking	881	Contains various utility functions that replace often-used but blocking
630	functions such as C<inet_aton> by event-/callback-based versions.	882	functions such as C<inet_aton> by event-/callback-based versions.
631		883
		884	=item L<AnyEvent::Socket>
		885
		886	Provides various utility functions for (internet protocol) sockets,
		887	addresses and name resolution. Also functions to create non-blocking tcp
		888	connections or tcp servers, with IPv6 and SRV record support and more.
		889
632	=item L<AnyEvent::Handle>	890	=item L<AnyEvent::Handle>
633		891
634	Provide read and write buffers and manages watchers for reads and writes.	892	Provide read and write buffers, manages watchers for reads and writes,
		893	supports raw and formatted I/O, I/O queued and fully transparent and
		894	non-blocking SSL/TLS.
		895
		896	=item L<AnyEvent::DNS>
		897
		898	Provides rich asynchronous DNS resolver capabilities.
		899
		900	=item L<AnyEvent::HTTP>
		901
		902	A simple-to-use HTTP library that is capable of making a lot of concurrent
		903	HTTP requests.
635		904
636	=item L<AnyEvent::HTTPD>	905	=item L<AnyEvent::HTTPD>
637		906
638	Provides a simple web application server framework.	907	Provides a simple web application server framework.
639		908
640	=item L<AnyEvent::DNS>
641
642	Provides asynchronous DNS resolver capabilities, beyond what
643	L<AnyEvent::Util> offers.
644
645	=item L<AnyEvent::FastPing>	909	=item L<AnyEvent::FastPing>
646		910
647	The fastest ping in the west.	911	The fastest ping in the west.
648		912
		913	=item L<AnyEvent::DBI>
		914
		915	Executes L<DBI> requests asynchronously in a proxy process.
		916
		917	=item L<AnyEvent::AIO>
		918
		919	Truly asynchronous I/O, should be in the toolbox of every event
		920	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		921	together.
		922
		923	=item L<AnyEvent::BDB>
		924
		925	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		926	L<BDB> and AnyEvent together.
		927
		928	=item L<AnyEvent::GPSD>
		929
		930	A non-blocking interface to gpsd, a daemon delivering GPS information.
		931
		932	=item L<AnyEvent::IGS>
		933
		934	A non-blocking interface to the Internet Go Server protocol (used by
		935	L<App::IGS>).
		936
649	=item L<Net::IRC3>	937	=item L<AnyEvent::IRC>
650		938
651	AnyEvent based IRC client module family.	939	AnyEvent based IRC client module family (replacing the older Net::IRC3).
652		940
653	=item L<Net::XMPP2>	941	=item L<Net::XMPP2>
654		942
655	AnyEvent based XMPP (Jabber protocol) module family.	943	AnyEvent based XMPP (Jabber protocol) module family.
656		944
…		…
665		953
666	=item L<Coro>	954	=item L<Coro>
667		955
668	Has special support for AnyEvent via L<Coro::AnyEvent>.	956	Has special support for AnyEvent via L<Coro::AnyEvent>.
669		957
670	=item L<AnyEvent::AIO>, L<IO::AIO>
671
672	Truly asynchronous I/O, should be in the toolbox of every event
673	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
674	together.
675
676	=item L<AnyEvent::BDB>, L<BDB>
677
678	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
679	IO::AIO and AnyEvent together.
680
681	=item L<IO::Lambda>	958	=item L<IO::Lambda>
682		959
683	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	960	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
684		961
685	=back	962	=back
…		…
687	=cut	964	=cut
688		965
689	package AnyEvent;	966	package AnyEvent;
690		967
691	no warnings;	968	no warnings;
692	use strict;	969	use strict qw(vars subs);
693		970
694	use Carp;	971	use Carp;
695		972
696	our $VERSION = '3.41';	973	our $VERSION = 4.8;
697	our $MODEL;	974	our $MODEL;
698		975
699	our $AUTOLOAD;	976	our $AUTOLOAD;
700	our @ISA;	977	our @ISA;
701		978
		979	our @REGISTRY;
		980
		981	our $WIN32;
		982
		983	BEGIN {
		984	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		985	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		986
		987	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		988	if ${^TAINT};
		989	}
		990
702	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	991	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
703		992
704	our @REGISTRY;	993	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		994
		995	{
		996	my $idx;
		997	$PROTOCOL{$_} = ++$idx
		998	for reverse split /\s*,\s*/,
		999	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1000	}
705		1001
706	my @models = (	1002	my @models = (
707	[EV:: => AnyEvent::Impl::EV::],	1003	[EV:: => AnyEvent::Impl::EV::],
708	[Event:: => AnyEvent::Impl::Event::],	1004	[Event:: => AnyEvent::Impl::Event::],
709	[Tk:: => AnyEvent::Impl::Tk::],
710	[Wx:: => AnyEvent::Impl::POE::],
711	[Prima:: => AnyEvent::Impl::POE::],
712	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1005	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
713	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1006	# everything below here will not be autoprobed
714	[Glib:: => AnyEvent::Impl::Glib::],	1007	# as the pureperl backend should work everywhere
		1008	# and is usually faster
		1009	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1010	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
715	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1011	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
716	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1012	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
717	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1013	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		1014	[Wx:: => AnyEvent::Impl::POE::],
		1015	[Prima:: => AnyEvent::Impl::POE::],
		1016	# IO::Async is just too broken - we would need workaorunds for its
		1017	# byzantine signal and broken child handling, among others.
		1018	# IO::Async is rather hard to detect, as it doesn't have any
		1019	# obvious default class.
		1020	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1021	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1022	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
718	);	1023	);
719		1024
720	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1025	our %method = map +($_ => 1),
		1026	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
721		1027
722	our @post_detect;	1028	our @post_detect;
723		1029
724	sub post_detect(&) {	1030	sub post_detect(&) {
725	my ($cb) = @_;	1031	my ($cb) = @_;
…		…
730	1	1036	1
731	} else {	1037	} else {
732	push @post_detect, $cb;	1038	push @post_detect, $cb;
733		1039
734	defined wantarray	1040	defined wantarray
735	? bless \$cb, "AnyEvent::Util::Guard"	1041	? bless \$cb, "AnyEvent::Util::postdetect"
736	: ()	1042	: ()
737	}	1043	}
738	}	1044	}
739		1045
740	sub AnyEvent::Util::Guard::DESTROY {	1046	sub AnyEvent::Util::postdetect::DESTROY {
741	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1047	@post_detect = grep $_ != ${$_[0]}, @post_detect;
742	}	1048	}
743		1049
744	sub detect() {	1050	sub detect() {
745	unless ($MODEL) {	1051	unless ($MODEL) {
746	no strict 'refs';	1052	no strict 'refs';
		1053	local $SIG{__DIE__};
747		1054
748	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1055	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
749	my $model = "AnyEvent::Impl::$1";	1056	my $model = "AnyEvent::Impl::$1";
750	if (eval "require $model") {	1057	if (eval "require $model") {
751	$MODEL = $model;	1058	$MODEL = $model;
…		…
781	last;	1088	last;
782	}	1089	}
783	}	1090	}
784		1091
785	$MODEL	1092	$MODEL
786	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1093	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
787	}	1094	}
788	}	1095	}
789		1096
		1097	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1098
790	unshift @ISA, $MODEL;	1099	unshift @ISA, $MODEL;
791	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1100
		1101	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
792		1102
793	(shift @post_detect)->() while @post_detect;	1103	(shift @post_detect)->() while @post_detect;
794	}	1104	}
795		1105
796	$MODEL	1106	$MODEL
…		…
806		1116
807	my $class = shift;	1117	my $class = shift;
808	$class->$func (@_);	1118	$class->$func (@_);
809	}	1119	}
810		1120
		1121	# utility function to dup a filehandle. this is used by many backends
		1122	# to support binding more than one watcher per filehandle (they usually
		1123	# allow only one watcher per fd, so we dup it to get a different one).
		1124	sub _dupfh($$;$$) {
		1125	my ($poll, $fh, $r, $w) = @_;
		1126
		1127	# cygwin requires the fh mode to be matching, unix doesn't
		1128	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1129	: $poll eq "w" ? ($w, ">")
		1130	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1131
		1132	open my $fh2, "$mode&" . fileno $fh
		1133	or die "cannot dup() filehandle: $!,";
		1134
		1135	# we assume CLOEXEC is already set by perl in all important cases
		1136
		1137	($fh2, $rw)
		1138	}
		1139
811	package AnyEvent::Base;	1140	package AnyEvent::Base;
812		1141
		1142	# default implementations for many methods
		1143
		1144	BEGIN {
		1145	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1146	*_time = \&Time::HiRes::time;
		1147	# if (eval "use POSIX (); (POSIX::times())...
		1148	} else {
		1149	*_time = sub { time }; # epic fail
		1150	}
		1151	}
		1152
		1153	sub time { _time }
		1154	sub now { _time }
		1155	sub now_update { }
		1156
813	# default implementation for ->condvar	1157	# default implementation for ->condvar
814		1158
815	sub condvar {	1159	sub condvar {
816	bless {}, AnyEvent::CondVar::	1160	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
817	}	1161	}
818		1162
819	# default implementation for ->signal	1163	# default implementation for ->signal
820		1164
821	our %SIG_CB;	1165	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1166
		1167	sub _signal_exec {
		1168	sysread $SIGPIPE_R, my $dummy, 4;
		1169
		1170	while (%SIG_EV) {
		1171	for (keys %SIG_EV) {
		1172	delete $SIG_EV{$_};
		1173	$_->() for values %{ $SIG_CB{$_} || {} };
		1174	}
		1175	}
		1176	}
822		1177
823	sub signal {	1178	sub signal {
824	my (undef, %arg) = @_;	1179	my (undef, %arg) = @_;
825		1180
		1181	unless ($SIGPIPE_R) {
		1182	require Fcntl;
		1183
		1184	if (AnyEvent::WIN32) {
		1185	require AnyEvent::Util;
		1186
		1187	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1188	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1189	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1190	} else {
		1191	pipe $SIGPIPE_R, $SIGPIPE_W;
		1192	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1193	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1194
		1195	# not strictly required, as $^F is normally 2, but let's make sure...
		1196	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1197	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1198	}
		1199
		1200	$SIGPIPE_R
		1201	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1202
		1203	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1204	}
		1205
826	my $signal = uc $arg{signal}	1206	my $signal = uc $arg{signal}
827	or Carp::croak "required option 'signal' is missing";	1207	or Carp::croak "required option 'signal' is missing";
828		1208
829	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1209	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
830	$SIG{$signal} ||= sub {	1210	$SIG{$signal} ||= sub {
831	$_->() for values %{ $SIG_CB{$signal} || {} };	1211	local $!;
		1212	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1213	undef $SIG_EV{$signal};
832	};	1214	};
833		1215
834	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1216	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
835	}	1217	}
836		1218
837	sub AnyEvent::Base::Signal::DESTROY {	1219	sub AnyEvent::Base::signal::DESTROY {
838	my ($signal, $cb) = @{$_[0]};	1220	my ($signal, $cb) = @{$_[0]};
839		1221
840	delete $SIG_CB{$signal}{$cb};	1222	delete $SIG_CB{$signal}{$cb};
841		1223
		1224	# delete doesn't work with older perls - they then
		1225	# print weird messages, or just unconditionally exit
		1226	# instead of getting the default action.
842	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1227	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
843	}	1228	}
844		1229
845	# default implementation for ->child	1230	# default implementation for ->child
846		1231
847	our %PID_CB;	1232	our %PID_CB;
848	our $CHLD_W;	1233	our $CHLD_W;
849	our $CHLD_DELAY_W;	1234	our $CHLD_DELAY_W;
850	our $PID_IDLE;
851	our $WNOHANG;	1235	our $WNOHANG;
852		1236
853	sub _child_wait {	1237	sub _sigchld {
854	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1238	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
855	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1239	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
856	(values %{ $PID_CB{0} || {} });	1240	(values %{ $PID_CB{0} || {} });
857	}	1241	}
858
859	undef $PID_IDLE;
860	}
861
862	sub _sigchld {
863	# make sure we deliver these changes "synchronous" with the event loop.
864	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
865	undef $CHLD_DELAY_W;
866	&_child_wait;
867	});
868	}	1242	}
869		1243
870	sub child {	1244	sub child {
871	my (undef, %arg) = @_;	1245	my (undef, %arg) = @_;
872		1246
873	defined (my $pid = $arg{pid} + 0)	1247	defined (my $pid = $arg{pid} + 0)
874	or Carp::croak "required option 'pid' is missing";	1248	or Carp::croak "required option 'pid' is missing";
875		1249
876	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1250	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
877		1251
878	unless ($WNOHANG) {
879	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1252	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
880	}
881		1253
882	unless ($CHLD_W) {	1254	unless ($CHLD_W) {
883	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1255	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
884	# child could be a zombie already, so make at least one round	1256	# child could be a zombie already, so make at least one round
885	&_sigchld;	1257	&_sigchld;
886	}	1258	}
887		1259
888	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1260	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
889	}	1261	}
890		1262
891	sub AnyEvent::Base::Child::DESTROY {	1263	sub AnyEvent::Base::child::DESTROY {
892	my ($pid, $cb) = @{$_[0]};	1264	my ($pid, $cb) = @{$_[0]};
893		1265
894	delete $PID_CB{$pid}{$cb};	1266	delete $PID_CB{$pid}{$cb};
895	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1267	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
896		1268
897	undef $CHLD_W unless keys %PID_CB;	1269	undef $CHLD_W unless keys %PID_CB;
898	}	1270	}
899		1271
		1272	# idle emulation is done by simply using a timer, regardless
		1273	# of whether the process is idle or not, and not letting
		1274	# the callback use more than 50% of the time.
		1275	sub idle {
		1276	my (undef, %arg) = @_;
		1277
		1278	my ($cb, $w, $rcb) = $arg{cb};
		1279
		1280	$rcb = sub {
		1281	if ($cb) {
		1282	$w = _time;
		1283	&$cb;
		1284	$w = _time - $w;
		1285
		1286	# never use more then 50% of the time for the idle watcher,
		1287	# within some limits
		1288	$w = 0.0001 if $w < 0.0001;
		1289	$w = 5 if $w > 5;
		1290
		1291	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1292	} else {
		1293	# clean up...
		1294	undef $w;
		1295	undef $rcb;
		1296	}
		1297	};
		1298
		1299	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1300
		1301	bless \\$cb, "AnyEvent::Base::idle"
		1302	}
		1303
		1304	sub AnyEvent::Base::idle::DESTROY {
		1305	undef $${$_[0]};
		1306	}
		1307
900	package AnyEvent::CondVar;	1308	package AnyEvent::CondVar;
901		1309
902	our @ISA = AnyEvent::CondVar::Base::;	1310	our @ISA = AnyEvent::CondVar::Base::;
903		1311
904	package AnyEvent::CondVar::Base;	1312	package AnyEvent::CondVar::Base;
		1313
		1314	use overload
		1315	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1316	fallback => 1;
905		1317
906	sub _send {	1318	sub _send {
907	# nop	1319	# nop
908	}	1320	}
909		1321
…		…
944	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1356	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
945	}	1357	}
946		1358
947	sub end {	1359	sub end {
948	return if --$_[0]{_ae_counter};	1360	return if --$_[0]{_ae_counter};
949	&{ $_[0]{_ae_end_cb} } if $_[0]{_ae_end_cb};	1361	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
950	}	1362	}
951		1363
952	# undocumented/compatibility with pre-3.4	1364	# undocumented/compatibility with pre-3.4
953	*broadcast = \&send;	1365	*broadcast = \&send;
954	*wait = \&_wait;	1366	*wait = \&_wait;
		1367
		1368	=head1 ERROR AND EXCEPTION HANDLING
		1369
		1370	In general, AnyEvent does not do any error handling - it relies on the
		1371	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1372	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1373	checking of all AnyEvent methods, however, which is highly useful during
		1374	development.
		1375
		1376	As for exception handling (i.e. runtime errors and exceptions thrown while
		1377	executing a callback), this is not only highly event-loop specific, but
		1378	also not in any way wrapped by this module, as this is the job of the main
		1379	program.
		1380
		1381	The pure perl event loop simply re-throws the exception (usually
		1382	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1383	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1384	so on.
		1385
		1386	=head1 ENVIRONMENT VARIABLES
		1387
		1388	The following environment variables are used by this module or its
		1389	submodules.
		1390
		1391	Note that AnyEvent will remove I<all> environment variables starting with
		1392	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1393	enabled.
		1394
		1395	=over 4
		1396
		1397	=item C<PERL_ANYEVENT_VERBOSE>
		1398
		1399	By default, AnyEvent will be completely silent except in fatal
		1400	conditions. You can set this environment variable to make AnyEvent more
		1401	talkative.
		1402
		1403	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1404	conditions, such as not being able to load the event model specified by
		1405	C<PERL_ANYEVENT_MODEL>.
		1406
		1407	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1408	model it chooses.
		1409
		1410	=item C<PERL_ANYEVENT_STRICT>
		1411
		1412	AnyEvent does not do much argument checking by default, as thorough
		1413	argument checking is very costly. Setting this variable to a true value
		1414	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1415	check the arguments passed to most method calls. If it finds any problems,
		1416	it will croak.
		1417
		1418	In other words, enables "strict" mode.
		1419
		1420	Unlike C<use strict>, it is definitely recommended to keep it off in
		1421	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1422	developing programs can be very useful, however.
		1423
		1424	=item C<PERL_ANYEVENT_MODEL>
		1425
		1426	This can be used to specify the event model to be used by AnyEvent, before
		1427	auto detection and -probing kicks in. It must be a string consisting
		1428	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1429	and the resulting module name is loaded and if the load was successful,
		1430	used as event model. If it fails to load AnyEvent will proceed with
		1431	auto detection and -probing.
		1432
		1433	This functionality might change in future versions.
		1434
		1435	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1436	could start your program like this:
		1437
		1438	PERL_ANYEVENT_MODEL=Perl perl ...
		1439
		1440	=item C<PERL_ANYEVENT_PROTOCOLS>
		1441
		1442	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1443	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1444	of auto probing).
		1445
		1446	Must be set to a comma-separated list of protocols or address families,
		1447	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1448	used, and preference will be given to protocols mentioned earlier in the
		1449	list.
		1450
		1451	This variable can effectively be used for denial-of-service attacks
		1452	against local programs (e.g. when setuid), although the impact is likely
		1453	small, as the program has to handle conenction and other failures anyways.
		1454
		1455	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1456	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1457	- only support IPv4, never try to resolve or contact IPv6
		1458	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1459	IPv6, but prefer IPv6 over IPv4.
		1460
		1461	=item C<PERL_ANYEVENT_EDNS0>
		1462
		1463	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1464	for DNS. This extension is generally useful to reduce DNS traffic, but
		1465	some (broken) firewalls drop such DNS packets, which is why it is off by
		1466	default.
		1467
		1468	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1469	EDNS0 in its DNS requests.
		1470
		1471	=item C<PERL_ANYEVENT_MAX_FORKS>
		1472
		1473	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1474	will create in parallel.
		1475
		1476	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1477
		1478	The default value for the C<max_outstanding> parameter for the default DNS
		1479	resolver - this is the maximum number of parallel DNS requests that are
		1480	sent to the DNS server.
		1481
		1482	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1483
		1484	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1485	configuration) in the default resolver. When set to the empty string, no
		1486	default config will be used.
		1487
		1488	=back
955		1489
956	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1490	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
957		1491
958	This is an advanced topic that you do not normally need to use AnyEvent in	1492	This is an advanced topic that you do not normally need to use AnyEvent in
959	a module. This section is only of use to event loop authors who want to	1493	a module. This section is only of use to event loop authors who want to
…		…
993		1527
994	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1528	I<rxvt-unicode> also cheats a bit by not providing blocking access to
995	condition variables: code blocking while waiting for a condition will	1529	condition variables: code blocking while waiting for a condition will
996	C<die>. This still works with most modules/usages, and blocking calls must	1530	C<die>. This still works with most modules/usages, and blocking calls must
997	not be done in an interactive application, so it makes sense.	1531	not be done in an interactive application, so it makes sense.
998
999	=head1 ENVIRONMENT VARIABLES
1000
1001	The following environment variables are used by this module:
1002
1003	=over 4
1004
1005	=item C<PERL_ANYEVENT_VERBOSE>
1006
1007	By default, AnyEvent will be completely silent except in fatal
1008	conditions. You can set this environment variable to make AnyEvent more
1009	talkative.
1010
1011	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1012	conditions, such as not being able to load the event model specified by
1013	C<PERL_ANYEVENT_MODEL>.
1014
1015	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1016	model it chooses.
1017
1018	=item C<PERL_ANYEVENT_MODEL>
1019
1020	This can be used to specify the event model to be used by AnyEvent, before
1021	autodetection and -probing kicks in. It must be a string consisting
1022	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1023	and the resulting module name is loaded and if the load was successful,
1024	used as event model. If it fails to load AnyEvent will proceed with
1025	autodetection and -probing.
1026
1027	This functionality might change in future versions.
1028
1029	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1030	could start your program like this:
1031
1032	PERL_ANYEVENT_MODEL=Perl perl ...
1033
1034	=back
1035		1532
1036	=head1 EXAMPLE PROGRAM	1533	=head1 EXAMPLE PROGRAM
1037		1534
1038	The following program uses an I/O watcher to read data from STDIN, a timer	1535	The following program uses an I/O watcher to read data from STDIN, a timer
1039	to display a message once per second, and a condition variable to quit the	1536	to display a message once per second, and a condition variable to quit the
…		…
1048	poll => 'r',	1545	poll => 'r',
1049	cb => sub {	1546	cb => sub {
1050	warn "io event <$_[0]>\n"; # will always output <r>	1547	warn "io event <$_[0]>\n"; # will always output <r>
1051	chomp (my $input = <STDIN>); # read a line	1548	chomp (my $input = <STDIN>); # read a line
1052	warn "read: $input\n"; # output what has been read	1549	warn "read: $input\n"; # output what has been read
1053	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1550	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1054	},	1551	},
1055	);	1552	);
1056		1553
1057	my $time_watcher; # can only be used once	1554	my $time_watcher; # can only be used once
1058		1555
…		…
1063	});	1560	});
1064	}	1561	}
1065		1562
1066	new_timer; # create first timer	1563	new_timer; # create first timer
1067		1564
1068	$cv->wait; # wait until user enters /^q/i	1565	$cv->recv; # wait until user enters /^q/i
1069		1566
1070	=head1 REAL-WORLD EXAMPLE	1567	=head1 REAL-WORLD EXAMPLE
1071		1568
1072	Consider the L<Net::FCP> module. It features (among others) the following	1569	Consider the L<Net::FCP> module. It features (among others) the following
1073	API calls, which are to freenet what HTTP GET requests are to http:	1570	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1123	syswrite $txn->{fh}, $txn->{request}	1620	syswrite $txn->{fh}, $txn->{request}
1124	or die "connection or write error";	1621	or die "connection or write error";
1125	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1622	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1126		1623
1127	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1624	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1128	result and signals any possible waiters that the request ahs finished:	1625	result and signals any possible waiters that the request has finished:
1129		1626
1130	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1627	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1131		1628
1132	if (end-of-file or data complete) {	1629	if (end-of-file or data complete) {
1133	$txn->{result} = $txn->{buf};	1630	$txn->{result} = $txn->{buf};
1134	$txn->{finished}->broadcast;	1631	$txn->{finished}->send;
1135	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1632	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1136	}	1633	}
1137		1634
1138	The C<result> method, finally, just waits for the finished signal (if the	1635	The C<result> method, finally, just waits for the finished signal (if the
1139	request was already finished, it doesn't wait, of course, and returns the	1636	request was already finished, it doesn't wait, of course, and returns the
1140	data:	1637	data:
1141		1638
1142	$txn->{finished}->wait;	1639	$txn->{finished}->recv;
1143	return $txn->{result};	1640	return $txn->{result};
1144		1641
1145	The actual code goes further and collects all errors (C<die>s, exceptions)	1642	The actual code goes further and collects all errors (C<die>s, exceptions)
1146	that occured during request processing. The C<result> method detects	1643	that occurred during request processing. The C<result> method detects
1147	whether an exception as thrown (it is stored inside the $txn object)	1644	whether an exception as thrown (it is stored inside the $txn object)
1148	and just throws the exception, which means connection errors and other	1645	and just throws the exception, which means connection errors and other
1149	problems get reported tot he code that tries to use the result, not in a	1646	problems get reported tot he code that tries to use the result, not in a
1150	random callback.	1647	random callback.
1151		1648
…		…
1182		1679
1183	my $quit = AnyEvent->condvar;	1680	my $quit = AnyEvent->condvar;
1184		1681
1185	$fcp->txn_client_get ($url)->cb (sub {	1682	$fcp->txn_client_get ($url)->cb (sub {
1186	...	1683	...
1187	$quit->broadcast;	1684	$quit->send;
1188	});	1685	});
1189		1686
1190	$quit->wait;	1687	$quit->recv;
1191		1688
1192		1689
1193	=head1 BENCHMARKS	1690	=head1 BENCHMARKS
1194		1691
1195	To give you an idea of the performance and overheads that AnyEvent adds	1692	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1197	of various event loops I prepared some benchmarks.	1694	of various event loops I prepared some benchmarks.
1198		1695
1199	=head2 BENCHMARKING ANYEVENT OVERHEAD	1696	=head2 BENCHMARKING ANYEVENT OVERHEAD
1200		1697
1201	Here is a benchmark of various supported event models used natively and	1698	Here is a benchmark of various supported event models used natively and
1202	through anyevent. The benchmark creates a lot of timers (with a zero	1699	through AnyEvent. The benchmark creates a lot of timers (with a zero
1203	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1700	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1204	which it is), lets them fire exactly once and destroys them again.	1701	which it is), lets them fire exactly once and destroys them again.
1205		1702
1206	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1703	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1207	distribution.	1704	distribution.
…		…
1224	all watchers, to avoid adding memory overhead. That means closure creation	1721	all watchers, to avoid adding memory overhead. That means closure creation
1225	and memory usage is not included in the figures.	1722	and memory usage is not included in the figures.
1226		1723
1227	I<invoke> is the time, in microseconds, used to invoke a simple	1724	I<invoke> is the time, in microseconds, used to invoke a simple
1228	callback. The callback simply counts down a Perl variable and after it was	1725	callback. The callback simply counts down a Perl variable and after it was
1229	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1726	invoked "watcher" times, it would C<< ->send >> a condvar once to
1230	signal the end of this phase.	1727	signal the end of this phase.
1231		1728
1232	I<destroy> is the time, in microseconds, that it takes to destroy a single	1729	I<destroy> is the time, in microseconds, that it takes to destroy a single
1233	watcher.	1730	watcher.
1234		1731
1235	=head3 Results	1732	=head3 Results
1236		1733
1237	name watchers bytes create invoke destroy comment	1734	name watchers bytes create invoke destroy comment
1238	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1735	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1239	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1736	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1240	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1737	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1241	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1738	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1242	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1739	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1243	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1740	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1741	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1742	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1244	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1743	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1245	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1744	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1246	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1745	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1247	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1746	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1248		1747
1249	=head3 Discussion	1748	=head3 Discussion
1250		1749
1251	The benchmark does I<not> measure scalability of the event loop very	1750	The benchmark does I<not> measure scalability of the event loop very
1252	well. For example, a select-based event loop (such as the pure perl one)	1751	well. For example, a select-based event loop (such as the pure perl one)
…		…
1277	performance becomes really bad with lots of file descriptors (and few of	1776	performance becomes really bad with lots of file descriptors (and few of
1278	them active), of course, but this was not subject of this benchmark.	1777	them active), of course, but this was not subject of this benchmark.
1279		1778
1280	The C<Event> module has a relatively high setup and callback invocation	1779	The C<Event> module has a relatively high setup and callback invocation
1281	cost, but overall scores in on the third place.	1780	cost, but overall scores in on the third place.
		1781
		1782	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1783	when using its pure perl backend.
1282		1784
1283	C<Glib>'s memory usage is quite a bit higher, but it features a	1785	C<Glib>'s memory usage is quite a bit higher, but it features a
1284	faster callback invocation and overall ends up in the same class as	1786	faster callback invocation and overall ends up in the same class as
1285	C<Event>. However, Glib scales extremely badly, doubling the number of	1787	C<Event>. However, Glib scales extremely badly, doubling the number of
1286	watchers increases the processing time by more than a factor of four,	1788	watchers increases the processing time by more than a factor of four,
…		…
1330		1832
1331	=back	1833	=back
1332		1834
1333	=head2 BENCHMARKING THE LARGE SERVER CASE	1835	=head2 BENCHMARKING THE LARGE SERVER CASE
1334		1836
1335	This benchmark atcually benchmarks the event loop itself. It works by	1837	This benchmark actually benchmarks the event loop itself. It works by
1336	creating a number of "servers": each server consists of a socketpair, a	1838	creating a number of "servers": each server consists of a socket pair, a
1337	timeout watcher that gets reset on activity (but never fires), and an I/O	1839	timeout watcher that gets reset on activity (but never fires), and an I/O
1338	watcher waiting for input on one side of the socket. Each time the socket	1840	watcher waiting for input on one side of the socket. Each time the socket
1339	watcher reads a byte it will write that byte to a random other "server".	1841	watcher reads a byte it will write that byte to a random other "server".
1340		1842
1341	The effect is that there will be a lot of I/O watchers, only part of which	1843	The effect is that there will be a lot of I/O watchers, only part of which
1342	are active at any one point (so there is a constant number of active	1844	are active at any one point (so there is a constant number of active
1343	fds for each loop iterstaion, but which fds these are is random). The	1845	fds for each loop iteration, but which fds these are is random). The
1344	timeout is reset each time something is read because that reflects how	1846	timeout is reset each time something is read because that reflects how
1345	most timeouts work (and puts extra pressure on the event loops).	1847	most timeouts work (and puts extra pressure on the event loops).
1346		1848
1347	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1849	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1348	(1%) are active. This mirrors the activity of large servers with many	1850	(1%) are active. This mirrors the activity of large servers with many
1349	connections, most of which are idle at any one point in time.	1851	connections, most of which are idle at any one point in time.
1350		1852
1351	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1853	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1352	distribution.	1854	distribution.
…		…
1354	=head3 Explanation of the columns	1856	=head3 Explanation of the columns
1355		1857
1356	I<sockets> is the number of sockets, and twice the number of "servers" (as	1858	I<sockets> is the number of sockets, and twice the number of "servers" (as
1357	each server has a read and write socket end).	1859	each server has a read and write socket end).
1358		1860
1359	I<create> is the time it takes to create a socketpair (which is	1861	I<create> is the time it takes to create a socket pair (which is
1360	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1862	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1361		1863
1362	I<request>, the most important value, is the time it takes to handle a	1864	I<request>, the most important value, is the time it takes to handle a
1363	single "request", that is, reading the token from the pipe and forwarding	1865	single "request", that is, reading the token from the pipe and forwarding
1364	it to another server. This includes deleting the old timeout and creating	1866	it to another server. This includes deleting the old timeout and creating
1365	a new one that moves the timeout into the future.	1867	a new one that moves the timeout into the future.
1366		1868
1367	=head3 Results	1869	=head3 Results
1368		1870
1369	name sockets create request	1871	name sockets create request
1370	EV 20000 69.01 11.16	1872	EV 20000 69.01 11.16
1371	Perl 20000 73.32 35.87	1873	Perl 20000 73.32 35.87
		1874	IOAsync 20000 157.00 98.14 epoll
		1875	IOAsync 20000 159.31 616.06 poll
1372	Event 20000 212.62 257.32	1876	Event 20000 212.62 257.32
1373	Glib 20000 651.16 1896.30	1877	Glib 20000 651.16 1896.30
1374	POE 20000 349.67 12317.24 uses POE::Loop::Event	1878	POE 20000 349.67 12317.24 uses POE::Loop::Event
1375		1879
1376	=head3 Discussion	1880	=head3 Discussion
1377		1881
1378	This benchmark I<does> measure scalability and overall performance of the	1882	This benchmark I<does> measure scalability and overall performance of the
1379	particular event loop.	1883	particular event loop.
…		…
1381	EV is again fastest. Since it is using epoll on my system, the setup time	1885	EV is again fastest. Since it is using epoll on my system, the setup time
1382	is relatively high, though.	1886	is relatively high, though.
1383		1887
1384	Perl surprisingly comes second. It is much faster than the C-based event	1888	Perl surprisingly comes second. It is much faster than the C-based event
1385	loops Event and Glib.	1889	loops Event and Glib.
		1890
		1891	IO::Async performs very well when using its epoll backend, and still quite
		1892	good compared to Glib when using its pure perl backend.
1386		1893
1387	Event suffers from high setup time as well (look at its code and you will	1894	Event suffers from high setup time as well (look at its code and you will
1388	understand why). Callback invocation also has a high overhead compared to	1895	understand why). Callback invocation also has a high overhead compared to
1389	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1896	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1390	uses select or poll in basically all documented configurations.	1897	uses select or poll in basically all documented configurations.
…		…
1437	speed most when you have lots of watchers, not when you only have a few of	1944	speed most when you have lots of watchers, not when you only have a few of
1438	them).	1945	them).
1439		1946
1440	EV is again fastest.	1947	EV is again fastest.
1441		1948
1442	Perl again comes second. It is noticably faster than the C-based event	1949	Perl again comes second. It is noticeably faster than the C-based event
1443	loops Event and Glib, although the difference is too small to really	1950	loops Event and Glib, although the difference is too small to really
1444	matter.	1951	matter.
1445		1952
1446	POE also performs much better in this case, but is is still far behind the	1953	POE also performs much better in this case, but is is still far behind the
1447	others.	1954	others.
…		…
1453	=item * C-based event loops perform very well with small number of	1960	=item * C-based event loops perform very well with small number of
1454	watchers, as the management overhead dominates.	1961	watchers, as the management overhead dominates.
1455		1962
1456	=back	1963	=back
1457		1964
		1965	=head2 THE IO::Lambda BENCHMARK
		1966
		1967	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1968	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1969	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1970	shouldn't come as a surprise to anybody). As such, the benchmark is
		1971	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1972	very optimal. But how would AnyEvent compare when used without the extra
		1973	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1974
		1975	The benchmark itself creates an echo-server, and then, for 500 times,
		1976	connects to the echo server, sends a line, waits for the reply, and then
		1977	creates the next connection. This is a rather bad benchmark, as it doesn't
		1978	test the efficiency of the framework or much non-blocking I/O, but it is a
		1979	benchmark nevertheless.
		1980
		1981	name runtime
		1982	Lambda/select 0.330 sec
		1983	+ optimized 0.122 sec
		1984	Lambda/AnyEvent 0.327 sec
		1985	+ optimized 0.138 sec
		1986	Raw sockets/select 0.077 sec
		1987	POE/select, components 0.662 sec
		1988	POE/select, raw sockets 0.226 sec
		1989	POE/select, optimized 0.404 sec
		1990
		1991	AnyEvent/select/nb 0.085 sec
		1992	AnyEvent/EV/nb 0.068 sec
		1993	+state machine 0.134 sec
		1994
		1995	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1996	benchmarks actually make blocking connects and use 100% blocking I/O,
		1997	defeating the purpose of an event-based solution. All of the newly
		1998	written AnyEvent benchmarks use 100% non-blocking connects (using
		1999	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2000	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2001	generally require a lot more bookkeeping and event handling than blocking
		2002	connects (which involve a single syscall only).
		2003
		2004	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2005	offers similar expressive power as POE and IO::Lambda, using conventional
		2006	Perl syntax. This means that both the echo server and the client are 100%
		2007	non-blocking, further placing it at a disadvantage.
		2008
		2009	As you can see, the AnyEvent + EV combination even beats the
		2010	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2011	backend easily beats IO::Lambda and POE.
		2012
		2013	And even the 100% non-blocking version written using the high-level (and
		2014	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2015	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2016	in a non-blocking way.
		2017
		2018	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2019	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2020	part of the IO::lambda distribution and were used without any changes.
		2021
		2022
		2023	=head1 SIGNALS
		2024
		2025	AnyEvent currently installs handlers for these signals:
		2026
		2027	=over 4
		2028
		2029	=item SIGCHLD
		2030
		2031	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2032	emulation for event loops that do not support them natively. Also, some
		2033	event loops install a similar handler.
		2034
		2035	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2036	reset it to default, to avoid losing child exit statuses.
		2037
		2038	=item SIGPIPE
		2039
		2040	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2041	when AnyEvent gets loaded.
		2042
		2043	The rationale for this is that AnyEvent users usually do not really depend
		2044	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2045	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2046	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2047	some random socket.
		2048
		2049	The rationale for installing a no-op handler as opposed to ignoring it is
		2050	that this way, the handler will be restored to defaults on exec.
		2051
		2052	Feel free to install your own handler, or reset it to defaults.
		2053
		2054	=back
		2055
		2056	=cut
		2057
		2058	undef $SIG{CHLD}
		2059	if $SIG{CHLD} eq 'IGNORE';
		2060
		2061	$SIG{PIPE} = sub { }
		2062	unless defined $SIG{PIPE};
1458		2063
1459	=head1 FORK	2064	=head1 FORK
1460		2065
1461	Most event libraries are not fork-safe. The ones who are usually are	2066	Most event libraries are not fork-safe. The ones who are usually are
1462	because they rely on inefficient but fork-safe C<select> or C<poll>	2067	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1476	specified in the variable.	2081	specified in the variable.
1477		2082
1478	You can make AnyEvent completely ignore this variable by deleting it	2083	You can make AnyEvent completely ignore this variable by deleting it
1479	before the first watcher gets created, e.g. with a C<BEGIN> block:	2084	before the first watcher gets created, e.g. with a C<BEGIN> block:
1480		2085
1481	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2086	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1482		2087
1483	use AnyEvent;	2088	use AnyEvent;
1484		2089
1485	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2090	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1486	be used to probe what backend is used and gain other information (which is	2091	be used to probe what backend is used and gain other information (which is
1487	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2092	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2093	$ENV{PERL_ANYEVENT_STRICT}.
		2094
		2095	Note that AnyEvent will remove I<all> environment variables starting with
		2096	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2097	enabled.
		2098
		2099
		2100	=head1 BUGS
		2101
		2102	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2103	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2104	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2105	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2106	pronounced).
1488		2107
1489		2108
1490	=head1 SEE ALSO	2109	=head1 SEE ALSO
		2110
		2111	Utility functions: L<AnyEvent::Util>.
1491		2112
1492	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2113	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1493	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2114	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1494		2115
1495	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2116	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1496	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2117	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1497	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2118	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1498	L<AnyEvent::Impl::POE>.	2119	L<AnyEvent::Impl::POE>.
1499		2120
		2121	Non-blocking file handles, sockets, TCP clients and
		2122	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		2123
		2124	Asynchronous DNS: L<AnyEvent::DNS>.
		2125
1500	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2126	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
1501		2127
1502	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2128	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1503		2129
1504		2130
1505	=head1 AUTHOR	2131	=head1 AUTHOR
1506		2132
1507	Marc Lehmann <schmorp@schmorp.de>	2133	Marc Lehmann <schmorp@schmorp.de>
1508	http://home.schmorp.de/	2134	http://home.schmorp.de/
1509		2135
1510	=cut	2136	=cut
1511		2137
1512	1	2138	1
1513		2139

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