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Revision 1.106 by root, Thu May 1 13:45:22 2008 UTC vs.
Revision 1.210 by root, Wed May 13 15:19:43 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
		11	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	12	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		13
		14	# one-shot or repeating timers
		15	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		16	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		17
		18	print AnyEvent->now; # prints current event loop time
		19	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		20
		21	# POSIX signal
		22	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		23
		24	# child process exit
		25	my $w = AnyEvent->child (pid => $pid, cb => sub {
		26	my ($pid, $status) = @_;
12	...	27	...
13	});	28	});
14		29
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	30	# called when event loop idle (if applicable)
16	...	31	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		32
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	33	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		34	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->send	35	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->send; # wake up current and all future wait's	36	# use a condvar in callback mode:
		37	$w->cb (sub { $_[0]->recv });
		38
		39	=head1 INTRODUCTION/TUTORIAL
		40
		41	This manpage is mainly a reference manual. If you are interested
		42	in a tutorial or some gentle introduction, have a look at the
		43	L<AnyEvent::Intro> manpage.
22		44
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	45	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		46
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	47	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	48	nowadays. So what is different about AnyEvent?
27		49
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	50	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	51	policy> and AnyEvent is I<small and efficient>.
30		52
31	First and foremost, I<AnyEvent is not an event model> itself, it only	53	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	54	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,	55	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,	56	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	57	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	58	cannot change this, but it can hide the differences between those event
		59	loops.
37		60
38	The goal of AnyEvent is to offer module authors the ability to do event	61	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	62	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	63	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	64	module users into the same thing by forcing them to use the same event
42	model you use.	65	model you use.
43		66
44	For modules like POE or IO::Async (which is a total misnomer as it is	67	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	68	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	69	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	70	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	71	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.	72	module are I<also> forced to use the same event loop you use.
50		73
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	74	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	75	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	76	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,	77	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	78	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	79	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	80	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).	81	to AnyEvent, too, so it is future-proof).
59		82
60	In addition to being free of having to use I<the one and only true event	83	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	84	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	85	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	86	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	87	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	88	technically possible.
66		89
		90	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		91	of useful functionality, such as an asynchronous DNS resolver, 100%
		92	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		93	such as Windows) and lots of real-world knowledge and workarounds for
		94	platform bugs and differences.
		95
67	Of course, if you want lots of policy (this can arguably be somewhat	96	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	97	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	98	model, you should I<not> use this module.
70		99
71	=head1 DESCRIPTION	100	=head1 DESCRIPTION
72		101
…		…
78	The interface itself is vaguely similar, but not identical to the L<Event>	107	The interface itself is vaguely similar, but not identical to the L<Event>
79	module.	108	module.
80		109
81	During the first call of any watcher-creation method, the module tries	110	During the first call of any watcher-creation method, the module tries
82	to detect the currently loaded event loop by probing whether one of the	111	to detect the currently loaded event loop by probing whether one of the
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	112	following modules is already loaded: L<EV>,
84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	113	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
85	L<POE>. The first one found is used. If none are found, the module tries	114	L<POE>. The first one found is used. If none are found, the module tries
86	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	115	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
87	adaptor should always succeed) in the order given. The first one that can	116	adaptor should always succeed) in the order given. The first one that can
88	be successfully loaded will be used. If, after this, still none could be	117	be successfully loaded will be used. If, after this, still none could be
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	131	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...	132	use AnyEvent so their modules work together with others seamlessly...
104		133
105	The pure-perl implementation of AnyEvent is called	134	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	135	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	136	explicitly and enjoy the high availability of that event loop :)
108		137
109	=head1 WATCHERS	138	=head1 WATCHERS
110		139
111	AnyEvent has the central concept of a I<watcher>, which is an object that	140	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	141	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	142	the callback to call, the file handle to watch, etc.
114		143
115	These watchers are normal Perl objects with normal Perl lifetime. After	144	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	145	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	146	callback when the event occurs (of course, only when the event model
118	is in control).	147	is in control).
119		148
		149	Note that B<callbacks must not permanently change global variables>
		150	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		151	callbacks must not C<die> >>. The former is good programming practise in
		152	Perl and the latter stems from the fact that exception handling differs
		153	widely between event loops.
		154
120	To disable the watcher you have to destroy it (e.g. by setting the	155	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	156	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	157	to it).
123		158
124	All watchers are created by calling a method on the C<AnyEvent> class.	159	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	161	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	162	example), or need to refer to their watcher object in other ways.
128		163
129	An any way to achieve that is this pattern:	164	An any way to achieve that is this pattern:
130		165
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	166	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	167	# you can use $w here, for example to undef it
133	undef $w;	168	undef $w;
134	});	169	});
135		170
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	171	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	172	my variables are only visible after the statement in which they are
138	declared.	173	declared.
139		174
140	=head2 I/O WATCHERS	175	=head2 I/O WATCHERS
141		176
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	177	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	178	with the following mandatory key-value pairs as arguments:
144		179
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	180	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		181	for events (AnyEvent might or might not keep a reference to this file
		182	handle). Note that only file handles pointing to things for which
		183	non-blocking operation makes sense are allowed. This includes sockets,
		184	most character devices, pipes, fifos and so on, but not for example files
		185	or block devices.
		186
146	for events. C<poll> must be a string that is either C<r> or C<w>,	187	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,	188	watcher waiting for "r"eadable or "w"ritable events, respectively.
		189
148	respectively. C<cb> is the callback to invoke each time the file handle	190	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		191
151	Although the callback might get passed parameters, their value and	192	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	193	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	194	callbacks cannot use arguments passed to I/O watcher callbacks.
154		195
…		…
158		199
159	Some event loops issue spurious readyness notifications, so you should	200	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	201	always use non-blocking calls when reading/writing from/to your file
161	handles.	202	handles.
162		203
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	204	Example: wait for readability of STDIN, then read a line and disable the
		205	watcher.
		206
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	207	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	208	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	209	warn "read: $input\n";
169	undef $w;	210	undef $w;
170	});	211	});
…		…
180		221
181	Although the callback might get passed parameters, their value and	222	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	223	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	224	callbacks cannot use arguments passed to time watcher callbacks.
184		225
185	The timer callback will be invoked at most once: if you want a repeating	226	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	227	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	228	callback will be invoked regularly at that interval (in fractional
		229	seconds) after the first invocation. If C<interval> is specified with a
		230	false value, then it is treated as if it were missing.
188		231
189	Example:	232	The callback will be rescheduled before invoking the callback, but no
		233	attempt is done to avoid timer drift in most backends, so the interval is
		234	only approximate.
190		235
191	# fire an event after 7.7 seconds	236	Example: fire an event after 7.7 seconds.
		237
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	238	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	239	warn "timeout\n";
194	});	240	});
195		241
196	# to cancel the timer:	242	# to cancel the timer:
197	undef $w;	243	undef $w;
198		244
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	245	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		246
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	247	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		248	warn "timeout\n";
207	};	249	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		250
212	=head3 TIMING ISSUES	251	=head3 TIMING ISSUES
213		252
214	There are two ways to handle timers: based on real time (relative, "fire	253	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	254	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	266	timers.
228		267
229	AnyEvent always prefers relative timers, if available, matching the	268	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	269	AnyEvent API.
231		270
		271	AnyEvent has two additional methods that return the "current time":
		272
		273	=over 4
		274
		275	=item AnyEvent->time
		276
		277	This returns the "current wallclock time" as a fractional number of
		278	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		279	return, and the result is guaranteed to be compatible with those).
		280
		281	It progresses independently of any event loop processing, i.e. each call
		282	will check the system clock, which usually gets updated frequently.
		283
		284	=item AnyEvent->now
		285
		286	This also returns the "current wallclock time", but unlike C<time>, above,
		287	this value might change only once per event loop iteration, depending on
		288	the event loop (most return the same time as C<time>, above). This is the
		289	time that AnyEvent's timers get scheduled against.
		290
		291	I<In almost all cases (in all cases if you don't care), this is the
		292	function to call when you want to know the current time.>
		293
		294	This function is also often faster then C<< AnyEvent->time >>, and
		295	thus the preferred method if you want some timestamp (for example,
		296	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		297
		298	The rest of this section is only of relevance if you try to be very exact
		299	with your timing, you can skip it without bad conscience.
		300
		301	For a practical example of when these times differ, consider L<Event::Lib>
		302	and L<EV> and the following set-up:
		303
		304	The event loop is running and has just invoked one of your callback at
		305	time=500 (assume no other callbacks delay processing). In your callback,
		306	you wait a second by executing C<sleep 1> (blocking the process for a
		307	second) and then (at time=501) you create a relative timer that fires
		308	after three seconds.
		309
		310	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		311	both return C<501>, because that is the current time, and the timer will
		312	be scheduled to fire at time=504 (C<501> + C<3>).
		313
		314	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		315	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		316	last event processing phase started. With L<EV>, your timer gets scheduled
		317	to run at time=503 (C<500> + C<3>).
		318
		319	In one sense, L<Event::Lib> is more exact, as it uses the current time
		320	regardless of any delays introduced by event processing. However, most
		321	callbacks do not expect large delays in processing, so this causes a
		322	higher drift (and a lot more system calls to get the current time).
		323
		324	In another sense, L<EV> is more exact, as your timer will be scheduled at
		325	the same time, regardless of how long event processing actually took.
		326
		327	In either case, if you care (and in most cases, you don't), then you
		328	can get whatever behaviour you want with any event loop, by taking the
		329	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		330	account.
		331
		332	=item AnyEvent->now_update
		333
		334	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		335	the current time for each loop iteration (see the discussion of L<<
		336	AnyEvent->now >>, above).
		337
		338	When a callback runs for a long time (or when the process sleeps), then
		339	this "current" time will differ substantially from the real time, which
		340	might affect timers and time-outs.
		341
		342	When this is the case, you can call this method, which will update the
		343	event loop's idea of "current time".
		344
		345	Note that updating the time I<might> cause some events to be handled.
		346
		347	=back
		348
232	=head2 SIGNAL WATCHERS	349	=head2 SIGNAL WATCHERS
233		350
234	You can watch for signals using a signal watcher, C<signal> is the signal	351	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	352	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	353	callback to be invoked whenever a signal occurs.
237		354
238	Although the callback might get passed parameters, their value and	355	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	356	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	357	callbacks cannot use arguments passed to signal watcher callbacks.
241		358
242	Multiple signal occurances can be clumped together into one callback	359	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	360	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	361	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.	362	but it is guaranteed not to interrupt any other callbacks.
246		363
247	The main advantage of using these watchers is that you can share a signal	364	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	365	between multiple watchers.
249		366
250	This watcher might use C<%SIG>, so programs overwriting those signals	367	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	374	=head2 CHILD PROCESS WATCHERS
258		375
259	You can also watch on a child process exit and catch its exit status.	376	You can also watch on a child process exit and catch its exit status.
260		377
261	The child process is specified by the C<pid> argument (if set to C<0>, it	378	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	379	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	380	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	381	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	382
266	you I<can> rely on child watcher callback arguments.	383	The callback will be called with the pid and exit status (as returned by
		384	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		385	callback arguments.
		386
		387	This watcher type works by installing a signal handler for C<SIGCHLD>,
		388	and since it cannot be shared, nothing else should use SIGCHLD or reap
		389	random child processes (waiting for specific child processes, e.g. inside
		390	C<system>, is just fine).
267		391
268	There is a slight catch to child watchers, however: you usually start them	392	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	393	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	394	have exited already (and no SIGCHLD will be sent anymore).
271		395
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	401	AnyEvent program, you I<have> to create at least one watcher before you
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	402	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		403
280	Example: fork a process and wait for it	404	Example: fork a process and wait for it
281		405
282	my $done = AnyEvent->condvar;	406	my $done = AnyEvent->condvar;
283		407
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	408	my $pid = fork or exit 5;
287		409
288	my $w = AnyEvent->child (	410	my $w = AnyEvent->child (
289	pid => $pid,	411	pid => $pid,
290	cb => sub {	412	cb => sub {
291	my ($pid, $status) = @_;	413	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	414	warn "pid $pid exited with status $status";
293	$done->send;	415	$done->send;
294	},	416	},
295	);	417	);
296		418
297	# do something else, then wait for process exit	419	# do something else, then wait for process exit
298	$done->wait;	420	$done->recv;
		421
		422	=head2 IDLE WATCHERS
		423
		424	Sometimes there is a need to do something, but it is not so important
		425	to do it instantly, but only when there is nothing better to do. This
		426	"nothing better to do" is usually defined to be "no other events need
		427	attention by the event loop".
		428
		429	Idle watchers ideally get invoked when the event loop has nothing
		430	better to do, just before it would block the process to wait for new
		431	events. Instead of blocking, the idle watcher is invoked.
		432
		433	Most event loops unfortunately do not really support idle watchers (only
		434	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		435	will simply call the callback "from time to time".
		436
		437	Example: read lines from STDIN, but only process them when the
		438	program is otherwise idle:
		439
		440	my @lines; # read data
		441	my $idle_w;
		442	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		443	push @lines, scalar <STDIN>;
		444
		445	# start an idle watcher, if not already done
		446	$idle_w ||= AnyEvent->idle (cb => sub {
		447	# handle only one line, when there are lines left
		448	if (my $line = shift @lines) {
		449	print "handled when idle: $line";
		450	} else {
		451	# otherwise disable the idle watcher again
		452	undef $idle_w;
		453	}
		454	});
		455	});
299		456
300	=head2 CONDITION VARIABLES	457	=head2 CONDITION VARIABLES
301		458
302	If you are familiar with some event loops you will know that all of them	459	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	460	require you to run some blocking "loop", "run" or similar function that
…		…
309	The instrument to do that is called a "condition variable", so called	466	The instrument to do that is called a "condition variable", so called
310	because they represent a condition that must become true.	467	because they represent a condition that must become true.
311		468
312	Condition variables can be created by calling the C<< AnyEvent->condvar	469	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	470	>> method, usually without arguments. The only argument pair allowed is
		471
314	C<cb>, which specifies a callback to be called when the condition variable	472	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	473	becomes true, with the condition variable as the first argument (but not
		474	the results).
316		475
317	After creation, the conditon variable is "false" until it becomes "true"	476	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<send> method.	477	by calling the C<send> method (or calling the condition variable as if it
		478	were a callback, read about the caveats in the description for the C<<
		479	->send >> method).
319		480
320	Condition variables are similar to callbacks, except that you can	481	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	482	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	483	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	484	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	485	used to represent a transaction, which finishes at some point and delivers
325	a result.	486	a result.
326		487
327	Condition variables are very useful to signal that something has finished,	488	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	489	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	490	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	491	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	492	called or can synchronously C<< ->recv >> for the results.
332		493
333	You can also use them to simulate traditional event loops - for example,	494	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	495	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	496	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->send >> the "quit" event.	497	button of your app, which would C<< ->send >> the "quit" event.
337		498
338	Note that condition variables recurse into the event loop - if you have	499	Note that condition variables recurse into the event loop - if you have
339	two pieces of code that call C<< ->wait >> in a round-robbin fashion, you	500	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	501	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	502	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	503	as this asks for trouble.
343		504
344	Condition variables are represented by hash refs in perl, and the keys	505	Condition variables are represented by hash refs in perl, and the keys
…		…
349		510
350	There are two "sides" to a condition variable - the "producer side" which	511	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> send >>, and the "consumer side", which waits	512	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the send to occur.	513	for the send to occur.
353		514
354	Example:	515	Example: wait for a timer.
355		516
356	# wait till the result is ready	517	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	518	my $result_ready = AnyEvent->condvar;
358		519
359	# do something such as adding a timer	520	# do something such as adding a timer
…		…
365	cb => sub { $result_ready->send },	526	cb => sub { $result_ready->send },
366	);	527	);
367		528
368	# this "blocks" (while handling events) till the callback	529	# this "blocks" (while handling events) till the callback
369	# calls send	530	# calls send
370	$result_ready->wait;	531	$result_ready->recv;
		532
		533	Example: wait for a timer, but take advantage of the fact that
		534	condition variables are also code references.
		535
		536	my $done = AnyEvent->condvar;
		537	my $delay = AnyEvent->timer (after => 5, cb => $done);
		538	$done->recv;
		539
		540	Example: Imagine an API that returns a condvar and doesn't support
		541	callbacks. This is how you make a synchronous call, for example from
		542	the main program:
		543
		544	use AnyEvent::CouchDB;
		545
		546	...
		547
		548	my @info = $couchdb->info->recv;
		549
		550	And this is how you would just ste a callback to be called whenever the
		551	results are available:
		552
		553	$couchdb->info->cb (sub {
		554	my @info = $_[0]->recv;
		555	});
371		556
372	=head3 METHODS FOR PRODUCERS	557	=head3 METHODS FOR PRODUCERS
373		558
374	These methods should only be used by the producing side, i.e. the	559	These methods should only be used by the producing side, i.e. the
375	code/module that eventually sends the signal. Note that it is also	560	code/module that eventually sends the signal. Note that it is also
…		…
378		563
379	=over 4	564	=over 4
380		565
381	=item $cv->send (...)	566	=item $cv->send (...)
382		567
383	Flag the condition as ready - a running C<< ->wait >> and all further	568	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	569	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the send will be remembered.	570	called. If nobody is waiting the send will be remembered.
386		571
387	If a callback has been set on the condition variable, it is called	572	If a callback has been set on the condition variable, it is called
388	immediately from within send.	573	immediately from within send.
389		574
390	Any arguments passed to the C<send> call will be returned by all	575	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	576	future C<< ->recv >> calls.
		577
		578	Condition variables are overloaded so one can call them directly
		579	(as a code reference). Calling them directly is the same as calling
		580	C<send>. Note, however, that many C-based event loops do not handle
		581	overloading, so as tempting as it may be, passing a condition variable
		582	instead of a callback does not work. Both the pure perl and EV loops
		583	support overloading, however, as well as all functions that use perl to
		584	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		585	example).
392		586
393	=item $cv->croak ($error)	587	=item $cv->croak ($error)
394		588
395	Similar to send, but causes all call's wait C<< ->wait >> to invoke	589	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	590	C<Carp::croak> with the given error message/object/scalar.
397		591
398	This can be used to signal any errors to the condition variable	592	This can be used to signal any errors to the condition variable
399	user/consumer.	593	user/consumer.
400		594
401	=item $cv->begin ([group callback])	595	=item $cv->begin ([group callback])
402		596
403	=item $cv->end	597	=item $cv->end
		598
		599	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		600
405	These two methods can be used to combine many transactions/events into	601	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	602	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	603	to use a condition variable for the whole process.
408		604
…		…
443	doesn't execute once).	639	doesn't execute once).
444		640
445	This is the general pattern when you "fan out" into multiple subrequests:	641	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	642	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	643	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	644	C<begin> and for each subrequest you finish, call C<end>.
449		645
450	=back	646	=back
451		647
452	=head3 METHODS FOR CONSUMERS	648	=head3 METHODS FOR CONSUMERS
453		649
454	These methods should only be used by the consuming side, i.e. the	650	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	651	code awaits the condition.
456		652
457	=over 4	653	=over 4
458		654
459	=item $cv->wait	655	=item $cv->recv
460		656
461	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	657	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
462	>> methods have been called on c<$cv>, while servicing other watchers	658	>> methods have been called on c<$cv>, while servicing other watchers
463	normally.	659	normally.
464		660
…		…
475	(programs might want to do that to stay interactive), so I<if you are	671	(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	672	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	673	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	674	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	675	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	676	while still supporting blocking waits if the caller so desires).
481		677
482	Another reason I<never> to C<< ->wait >> in a module is that you cannot	678	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->wait >>'s in parallel, as that would require	679	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	680	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	681	can supply.
486	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
487	from different coroutines, however).
488		682
		683	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		684	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		685	versions and also integrates coroutines into AnyEvent, making blocking
		686	C<< ->recv >> calls perfectly safe as long as they are done from another
		687	coroutine (one that doesn't run the event loop).
		688
489	You can ensure that C<< -wait >> never blocks by setting a callback and	689	You can ensure that C<< -recv >> never blocks by setting a callback and
490	only calling C<< ->wait >> from within that callback (or at a later	690	only calling C<< ->recv >> from within that callback (or at a later
491	time). This will work even when the event loop does not support blocking	691	time). This will work even when the event loop does not support blocking
492	waits otherwise.	692	waits otherwise.
493		693
494	=item $bool = $cv->ready	694	=item $bool = $cv->ready
495		695
496	Returns true when the condition is "true", i.e. whether C<send> or	696	Returns true when the condition is "true", i.e. whether C<send> or
497	C<croak> have been called.	697	C<croak> have been called.
498		698
499	=item $cb = $cv->cb ([new callback])	699	=item $cb = $cv->cb ($cb->($cv))
500		700
501	This is a mutator function that returns the callback set and optionally	701	This is a mutator function that returns the callback set and optionally
502	replaces it before doing so.	702	replaces it before doing so.
503		703
504	The callback will be called when the condition becomes "true", i.e. when	704	The callback will be called when the condition becomes "true", i.e. when
505	C<send> or C<croak> are called. Calling C<wait> inside the callback	705	C<send> or C<croak> are called, with the only argument being the condition
506	or at any later time is guaranteed not to block.	706	variable itself. Calling C<recv> inside the callback or at any later time
		707	is guaranteed not to block.
507		708
508	=back	709	=back
509		710
510	=head1 GLOBAL VARIABLES AND FUNCTIONS	711	=head1 GLOBAL VARIABLES AND FUNCTIONS
511		712
…		…
519	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	720	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
520	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	721	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
521		722
522	The known classes so far are:	723	The known classes so far are:
523		724
524	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
525	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
526	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	725	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
527	AnyEvent::Impl::Event based on Event, second best choice.	726	AnyEvent::Impl::Event based on Event, second best choice.
528	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	727	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
529	AnyEvent::Impl::Glib based on Glib, third-best choice.	728	AnyEvent::Impl::Glib based on Glib, third-best choice.
530	AnyEvent::Impl::Tk based on Tk, very bad choice.	729	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
547	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	746	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
548	if necessary. You should only call this function right before you would	747	if necessary. You should only call this function right before you would
549	have created an AnyEvent watcher anyway, that is, as late as possible at	748	have created an AnyEvent watcher anyway, that is, as late as possible at
550	runtime.	749	runtime.
551		750
		751	=item $guard = AnyEvent::post_detect { BLOCK }
		752
		753	Arranges for the code block to be executed as soon as the event model is
		754	autodetected (or immediately if this has already happened).
		755
		756	If called in scalar or list context, then it creates and returns an object
		757	that automatically removes the callback again when it is destroyed. See
		758	L<Coro::BDB> for a case where this is useful.
		759
		760	=item @AnyEvent::post_detect
		761
		762	If there are any code references in this array (you can C<push> to it
		763	before or after loading AnyEvent), then they will called directly after
		764	the event loop has been chosen.
		765
		766	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		767	if it contains a true value then the event loop has already been detected,
		768	and the array will be ignored.
		769
		770	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		771
552	=back	772	=back
553		773
554	=head1 WHAT TO DO IN A MODULE	774	=head1 WHAT TO DO IN A MODULE
555		775
556	As a module author, you should C<use AnyEvent> and call AnyEvent methods	776	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
559	Be careful when you create watchers in the module body - AnyEvent will	779	Be careful when you create watchers in the module body - AnyEvent will
560	decide which event module to use as soon as the first method is called, so	780	decide which event module to use as soon as the first method is called, so
561	by calling AnyEvent in your module body you force the user of your module	781	by calling AnyEvent in your module body you force the user of your module
562	to load the event module first.	782	to load the event module first.
563		783
564	Never call C<< ->wait >> on a condition variable unless you I<know> that	784	Never call C<< ->recv >> on a condition variable unless you I<know> that
565	the C<< ->send >> method has been called on it already. This is	785	the C<< ->send >> method has been called on it already. This is
566	because it will stall the whole program, and the whole point of using	786	because it will stall the whole program, and the whole point of using
567	events is to stay interactive.	787	events is to stay interactive.
568		788
569	It is fine, however, to call C<< ->wait >> when the user of your module	789	It is fine, however, to call C<< ->recv >> when the user of your module
570	requests it (i.e. if you create a http request object ad have a method	790	requests it (i.e. if you create a http request object ad have a method
571	called C<results> that returns the results, it should call C<< ->wait >>	791	called C<results> that returns the results, it should call C<< ->recv >>
572	freely, as the user of your module knows what she is doing. always).	792	freely, as the user of your module knows what she is doing. always).
573		793
574	=head1 WHAT TO DO IN THE MAIN PROGRAM	794	=head1 WHAT TO DO IN THE MAIN PROGRAM
575		795
576	There will always be a single main program - the only place that should	796	There will always be a single main program - the only place that should
…		…
578		798
579	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	799	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
580	do anything special (it does not need to be event-based) and let AnyEvent	800	do anything special (it does not need to be event-based) and let AnyEvent
581	decide which implementation to chose if some module relies on it.	801	decide which implementation to chose if some module relies on it.
582		802
583	If the main program relies on a specific event model. For example, in	803	If the main program relies on a specific event model - for example, in
584	Gtk2 programs you have to rely on the Glib module. You should load the	804	Gtk2 programs you have to rely on the Glib module - you should load the
585	event module before loading AnyEvent or any module that uses it: generally	805	event module before loading AnyEvent or any module that uses it: generally
586	speaking, you should load it as early as possible. The reason is that	806	speaking, you should load it as early as possible. The reason is that
587	modules might create watchers when they are loaded, and AnyEvent will	807	modules might create watchers when they are loaded, and AnyEvent will
588	decide on the event model to use as soon as it creates watchers, and it	808	decide on the event model to use as soon as it creates watchers, and it
589	might chose the wrong one unless you load the correct one yourself.	809	might chose the wrong one unless you load the correct one yourself.
590		810
591	You can chose to use a rather inefficient pure-perl implementation by	811	You can chose to use a pure-perl implementation by loading the
592	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	812	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
593	behaviour everywhere, but letting AnyEvent chose is generally better.	813	everywhere, but letting AnyEvent chose the model is generally better.
		814
		815	=head2 MAINLOOP EMULATION
		816
		817	Sometimes (often for short test scripts, or even standalone programs who
		818	only want to use AnyEvent), you do not want to run a specific event loop.
		819
		820	In that case, you can use a condition variable like this:
		821
		822	AnyEvent->condvar->recv;
		823
		824	This has the effect of entering the event loop and looping forever.
		825
		826	Note that usually your program has some exit condition, in which case
		827	it is better to use the "traditional" approach of storing a condition
		828	variable somewhere, waiting for it, and sending it when the program should
		829	exit cleanly.
		830
594		831
595	=head1 OTHER MODULES	832	=head1 OTHER MODULES
596		833
597	The following is a non-exhaustive list of additional modules that use	834	The following is a non-exhaustive list of additional modules that use
598	AnyEvent and can therefore be mixed easily with other AnyEvent modules	835	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
604	=item L<AnyEvent::Util>	841	=item L<AnyEvent::Util>
605		842
606	Contains various utility functions that replace often-used but blocking	843	Contains various utility functions that replace often-used but blocking
607	functions such as C<inet_aton> by event-/callback-based versions.	844	functions such as C<inet_aton> by event-/callback-based versions.
608		845
		846	=item L<AnyEvent::Socket>
		847
		848	Provides various utility functions for (internet protocol) sockets,
		849	addresses and name resolution. Also functions to create non-blocking tcp
		850	connections or tcp servers, with IPv6 and SRV record support and more.
		851
609	=item L<AnyEvent::Handle>	852	=item L<AnyEvent::Handle>
610		853
611	Provide read and write buffers and manages watchers for reads and writes.	854	Provide read and write buffers, manages watchers for reads and writes,
		855	supports raw and formatted I/O, I/O queued and fully transparent and
		856	non-blocking SSL/TLS.
612		857
613	=item L<AnyEvent::Socket>	858	=item L<AnyEvent::DNS>
614		859
615	Provides a means to do non-blocking connects, accepts etc.	860	Provides rich asynchronous DNS resolver capabilities.
		861
		862	=item L<AnyEvent::HTTP>
		863
		864	A simple-to-use HTTP library that is capable of making a lot of concurrent
		865	HTTP requests.
616		866
617	=item L<AnyEvent::HTTPD>	867	=item L<AnyEvent::HTTPD>
618		868
619	Provides a simple web application server framework.	869	Provides a simple web application server framework.
620		870
621	=item L<AnyEvent::DNS>
622
623	Provides asynchronous DNS resolver capabilities, beyond what
624	L<AnyEvent::Util> offers.
625
626	=item L<AnyEvent::FastPing>	871	=item L<AnyEvent::FastPing>
627		872
628	The fastest ping in the west.	873	The fastest ping in the west.
629		874
		875	=item L<AnyEvent::DBI>
		876
		877	Executes L<DBI> requests asynchronously in a proxy process.
		878
		879	=item L<AnyEvent::AIO>
		880
		881	Truly asynchronous I/O, should be in the toolbox of every event
		882	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		883	together.
		884
		885	=item L<AnyEvent::BDB>
		886
		887	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		888	L<BDB> and AnyEvent together.
		889
		890	=item L<AnyEvent::GPSD>
		891
		892	A non-blocking interface to gpsd, a daemon delivering GPS information.
		893
		894	=item L<AnyEvent::IGS>
		895
		896	A non-blocking interface to the Internet Go Server protocol (used by
		897	L<App::IGS>).
		898
630	=item L<Net::IRC3>	899	=item L<AnyEvent::IRC>
631		900
632	AnyEvent based IRC client module family.	901	AnyEvent based IRC client module family (replacing the older Net::IRC3).
633		902
634	=item L<Net::XMPP2>	903	=item L<Net::XMPP2>
635		904
636	AnyEvent based XMPP (Jabber protocol) module family.	905	AnyEvent based XMPP (Jabber protocol) module family.
637		906
…		…
644		913
645	High level API for event-based execution flow control.	914	High level API for event-based execution flow control.
646		915
647	=item L<Coro>	916	=item L<Coro>
648		917
649	Has special support for AnyEvent.	918	Has special support for AnyEvent via L<Coro::AnyEvent>.
650		919
651	=item L<IO::Lambda>	920	=item L<IO::Lambda>
652		921
653	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	922	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
654		923
655	=item L<IO::AIO>
656
657	Truly asynchronous I/O, should be in the toolbox of every event
658	programmer. Can be trivially made to use AnyEvent.
659
660	=item L<BDB>
661
662	Truly asynchronous Berkeley DB access. Can be trivially made to use
663	AnyEvent.
664
665	=back	924	=back
666		925
667	=cut	926	=cut
668		927
669	package AnyEvent;	928	package AnyEvent;
670		929
671	no warnings;	930	no warnings;
672	use strict;	931	use strict qw(vars subs);
673		932
674	use Carp;	933	use Carp;
675		934
676	our $VERSION = '3.3';	935	our $VERSION = 4.41;
677	our $MODEL;	936	our $MODEL;
678		937
679	our $AUTOLOAD;	938	our $AUTOLOAD;
680	our @ISA;	939	our @ISA;
681		940
		941	our @REGISTRY;
		942
		943	our $WIN32;
		944
		945	BEGIN {
		946	my $win32 = ! ! ($^O =~ /mswin32/i);
		947	eval "sub WIN32(){ $win32 }";
		948	}
		949
682	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	950	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
683		951
684	our @REGISTRY;	952	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		953
		954	{
		955	my $idx;
		956	$PROTOCOL{$_} = ++$idx
		957	for reverse split /\s*,\s*/,
		958	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		959	}
685		960
686	my @models = (	961	my @models = (
687	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
688	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
689	[EV:: => AnyEvent::Impl::EV::],	962	[EV:: => AnyEvent::Impl::EV::],
690	[Event:: => AnyEvent::Impl::Event::],	963	[Event:: => AnyEvent::Impl::Event::],
691	[Tk:: => AnyEvent::Impl::Tk::],
692	[Wx:: => AnyEvent::Impl::POE::],
693	[Prima:: => AnyEvent::Impl::POE::],
694	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	964	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
695	# everything below here will not be autoprobed as the pureperl backend should work everywhere	965	# everything below here will not be autoprobed
696	[Glib:: => AnyEvent::Impl::Glib::],	966	# as the pureperl backend should work everywhere
		967	# and is usually faster
		968	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		969	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
697	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	970	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
698	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	971	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
699	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	972	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		973	[Wx:: => AnyEvent::Impl::POE::],
		974	[Prima:: => AnyEvent::Impl::POE::],
700	);	975	);
701		976
702	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	977	our %method = map +($_ => 1),
		978	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		979
		980	our @post_detect;
		981
		982	sub post_detect(&) {
		983	my ($cb) = @_;
		984
		985	if ($MODEL) {
		986	$cb->();
		987
		988	1
		989	} else {
		990	push @post_detect, $cb;
		991
		992	defined wantarray
		993	? bless \$cb, "AnyEvent::Util::postdetect"
		994	: ()
		995	}
		996	}
		997
		998	sub AnyEvent::Util::postdetect::DESTROY {
		999	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1000	}
703		1001
704	sub detect() {	1002	sub detect() {
705	unless ($MODEL) {	1003	unless ($MODEL) {
706	no strict 'refs';	1004	no strict 'refs';
		1005	local $SIG{__DIE__};
707		1006
708	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1007	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
709	my $model = "AnyEvent::Impl::$1";	1008	my $model = "AnyEvent::Impl::$1";
710	if (eval "require $model") {	1009	if (eval "require $model") {
711	$MODEL = $model;	1010	$MODEL = $model;
…		…
741	last;	1040	last;
742	}	1041	}
743	}	1042	}
744		1043
745	$MODEL	1044	$MODEL
746	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1045	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
747	}	1046	}
748	}	1047	}
749		1048
		1049	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1050
750	unshift @ISA, $MODEL;	1051	unshift @ISA, $MODEL;
751	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1052
		1053	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1054
		1055	(shift @post_detect)->() while @post_detect;
752	}	1056	}
753		1057
754	$MODEL	1058	$MODEL
755	}	1059	}
756		1060
…		…
764		1068
765	my $class = shift;	1069	my $class = shift;
766	$class->$func (@_);	1070	$class->$func (@_);
767	}	1071	}
768		1072
		1073	# utility function to dup a filehandle. this is used by many backends
		1074	# to support binding more than one watcher per filehandle (they usually
		1075	# allow only one watcher per fd, so we dup it to get a different one).
		1076	sub _dupfh($$$$) {
		1077	my ($poll, $fh, $r, $w) = @_;
		1078
		1079	# cygwin requires the fh mode to be matching, unix doesn't
		1080	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1081	: $poll eq "w" ? ($w, ">")
		1082	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1083
		1084	open my $fh2, "$mode&" . fileno $fh
		1085	or die "cannot dup() filehandle: $!,";
		1086
		1087	# we assume CLOEXEC is already set by perl in all important cases
		1088
		1089	($fh2, $rw)
		1090	}
		1091
769	package AnyEvent::Base;	1092	package AnyEvent::Base;
770		1093
		1094	# default implementations for many methods
		1095
		1096	BEGIN {
		1097	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1098	*_time = \&Time::HiRes::time;
		1099	# if (eval "use POSIX (); (POSIX::times())...
		1100	} else {
		1101	*_time = sub { time }; # epic fail
		1102	}
		1103	}
		1104
		1105	sub time { _time }
		1106	sub now { _time }
		1107	sub now_update { }
		1108
771	# default implementation for ->condvar, ->wait, ->broadcast	1109	# default implementation for ->condvar
772		1110
773	sub condvar {	1111	sub condvar {
774	bless \my $flag, "AnyEvent::Base::CondVar"	1112	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
775	}
776
777	sub AnyEvent::Base::CondVar::broadcast {
778	${$_[0]}++;
779	}
780
781	sub AnyEvent::Base::CondVar::wait {
782	AnyEvent->one_event while !${$_[0]};
783	}	1113	}
784		1114
785	# default implementation for ->signal	1115	# default implementation for ->signal
786		1116
787	our %SIG_CB;	1117	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1118
		1119	sub _signal_exec {
		1120	sysread $SIGPIPE_R, my $dummy, 4;
		1121
		1122	while (%SIG_EV) {
		1123	for (keys %SIG_EV) {
		1124	delete $SIG_EV{$_};
		1125	$_->() for values %{ $SIG_CB{$_} || {} };
		1126	}
		1127	}
		1128	}
788		1129
789	sub signal {	1130	sub signal {
790	my (undef, %arg) = @_;	1131	my (undef, %arg) = @_;
791		1132
		1133	unless ($SIGPIPE_R) {
		1134	require Fcntl;
		1135
		1136	if (AnyEvent::WIN32) {
		1137	require AnyEvent::Util;
		1138
		1139	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1140	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1141	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1142	} else {
		1143	pipe $SIGPIPE_R, $SIGPIPE_W;
		1144	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1145	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1146	}
		1147
		1148	$SIGPIPE_R
		1149	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154
		1155	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1156	}
		1157
792	my $signal = uc $arg{signal}	1158	my $signal = uc $arg{signal}
793	or Carp::croak "required option 'signal' is missing";	1159	or Carp::croak "required option 'signal' is missing";
794		1160
795	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1161	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
796	$SIG{$signal} ||= sub {	1162	$SIG{$signal} ||= sub {
797	$_->() for values %{ $SIG_CB{$signal} || {} };	1163	local $!;
		1164	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1165	undef $SIG_EV{$signal};
798	};	1166	};
799		1167
800	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1168	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
801	}	1169	}
802		1170
803	sub AnyEvent::Base::Signal::DESTROY {	1171	sub AnyEvent::Base::signal::DESTROY {
804	my ($signal, $cb) = @{$_[0]};	1172	my ($signal, $cb) = @{$_[0]};
805		1173
806	delete $SIG_CB{$signal}{$cb};	1174	delete $SIG_CB{$signal}{$cb};
807		1175
		1176	# delete doesn't work with older perls - they then
		1177	# print weird messages, or just unconditionally exit
		1178	# instead of getting the default action.
808	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1179	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
809	}	1180	}
810		1181
811	# default implementation for ->child	1182	# default implementation for ->child
812		1183
813	our %PID_CB;	1184	our %PID_CB;
814	our $CHLD_W;	1185	our $CHLD_W;
815	our $CHLD_DELAY_W;	1186	our $CHLD_DELAY_W;
816	our $PID_IDLE;
817	our $WNOHANG;	1187	our $WNOHANG;
818		1188
819	sub _child_wait {	1189	sub _sigchld {
820	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1190	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
821	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1191	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
822	(values %{ $PID_CB{0} || {} });	1192	(values %{ $PID_CB{0} || {} });
823	}	1193	}
824
825	undef $PID_IDLE;
826	}
827
828	sub _sigchld {
829	# make sure we deliver these changes "synchronous" with the event loop.
830	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
831	undef $CHLD_DELAY_W;
832	&_child_wait;
833	});
834	}	1194	}
835		1195
836	sub child {	1196	sub child {
837	my (undef, %arg) = @_;	1197	my (undef, %arg) = @_;
838		1198
839	defined (my $pid = $arg{pid} + 0)	1199	defined (my $pid = $arg{pid} + 0)
840	or Carp::croak "required option 'pid' is missing";	1200	or Carp::croak "required option 'pid' is missing";
841		1201
842	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1202	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
843		1203
844	unless ($WNOHANG) {
845	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1204	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
846	}
847		1205
848	unless ($CHLD_W) {	1206	unless ($CHLD_W) {
849	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1207	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
850	# child could be a zombie already, so make at least one round	1208	# child could be a zombie already, so make at least one round
851	&_sigchld;	1209	&_sigchld;
852	}	1210	}
853		1211
854	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1212	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
855	}	1213	}
856		1214
857	sub AnyEvent::Base::Child::DESTROY {	1215	sub AnyEvent::Base::child::DESTROY {
858	my ($pid, $cb) = @{$_[0]};	1216	my ($pid, $cb) = @{$_[0]};
859		1217
860	delete $PID_CB{$pid}{$cb};	1218	delete $PID_CB{$pid}{$cb};
861	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1219	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
862		1220
863	undef $CHLD_W unless keys %PID_CB;	1221	undef $CHLD_W unless keys %PID_CB;
864	}	1222	}
		1223
		1224	# idle emulation is done by simply using a timer, regardless
		1225	# of whether the process is idle or not, and not letting
		1226	# the callback use more than 50% of the time.
		1227	sub idle {
		1228	my (undef, %arg) = @_;
		1229
		1230	my ($cb, $w, $rcb) = $arg{cb};
		1231
		1232	$rcb = sub {
		1233	if ($cb) {
		1234	$w = _time;
		1235	&$cb;
		1236	$w = _time - $w;
		1237
		1238	# never use more then 50% of the time for the idle watcher,
		1239	# within some limits
		1240	$w = 0.0001 if $w < 0.0001;
		1241	$w = 5 if $w > 5;
		1242
		1243	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1244	} else {
		1245	# clean up...
		1246	undef $w;
		1247	undef $rcb;
		1248	}
		1249	};
		1250
		1251	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1252
		1253	bless \\$cb, "AnyEvent::Base::idle"
		1254	}
		1255
		1256	sub AnyEvent::Base::idle::DESTROY {
		1257	undef $${$_[0]};
		1258	}
		1259
		1260	package AnyEvent::CondVar;
		1261
		1262	our @ISA = AnyEvent::CondVar::Base::;
		1263
		1264	package AnyEvent::CondVar::Base;
		1265
		1266	use overload
		1267	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1268	fallback => 1;
		1269
		1270	sub _send {
		1271	# nop
		1272	}
		1273
		1274	sub send {
		1275	my $cv = shift;
		1276	$cv->{_ae_sent} = [@_];
		1277	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1278	$cv->_send;
		1279	}
		1280
		1281	sub croak {
		1282	$_[0]{_ae_croak} = $_[1];
		1283	$_[0]->send;
		1284	}
		1285
		1286	sub ready {
		1287	$_[0]{_ae_sent}
		1288	}
		1289
		1290	sub _wait {
		1291	AnyEvent->one_event while !$_[0]{_ae_sent};
		1292	}
		1293
		1294	sub recv {
		1295	$_[0]->_wait;
		1296
		1297	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1298	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1299	}
		1300
		1301	sub cb {
		1302	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1303	$_[0]{_ae_cb}
		1304	}
		1305
		1306	sub begin {
		1307	++$_[0]{_ae_counter};
		1308	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1309	}
		1310
		1311	sub end {
		1312	return if --$_[0]{_ae_counter};
		1313	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1314	}
		1315
		1316	# undocumented/compatibility with pre-3.4
		1317	*broadcast = \&send;
		1318	*wait = \&_wait;
		1319
		1320	=head1 ERROR AND EXCEPTION HANDLING
		1321
		1322	In general, AnyEvent does not do any error handling - it relies on the
		1323	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1324	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1325	checking of all AnyEvent methods, however, which is highly useful during
		1326	development.
		1327
		1328	As for exception handling (i.e. runtime errors and exceptions thrown while
		1329	executing a callback), this is not only highly event-loop specific, but
		1330	also not in any way wrapped by this module, as this is the job of the main
		1331	program.
		1332
		1333	The pure perl event loop simply re-throws the exception (usually
		1334	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1335	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1336	so on.
		1337
		1338	=head1 ENVIRONMENT VARIABLES
		1339
		1340	The following environment variables are used by this module or its
		1341	submodules:
		1342
		1343	=over 4
		1344
		1345	=item C<PERL_ANYEVENT_VERBOSE>
		1346
		1347	By default, AnyEvent will be completely silent except in fatal
		1348	conditions. You can set this environment variable to make AnyEvent more
		1349	talkative.
		1350
		1351	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1352	conditions, such as not being able to load the event model specified by
		1353	C<PERL_ANYEVENT_MODEL>.
		1354
		1355	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1356	model it chooses.
		1357
		1358	=item C<PERL_ANYEVENT_STRICT>
		1359
		1360	AnyEvent does not do much argument checking by default, as thorough
		1361	argument checking is very costly. Setting this variable to a true value
		1362	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1363	check the arguments passed to most method calls. If it finds any problems
		1364	it will croak.
		1365
		1366	In other words, enables "strict" mode.
		1367
		1368	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1369	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1370	developing programs can be very useful, however.
		1371
		1372	=item C<PERL_ANYEVENT_MODEL>
		1373
		1374	This can be used to specify the event model to be used by AnyEvent, before
		1375	auto detection and -probing kicks in. It must be a string consisting
		1376	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1377	and the resulting module name is loaded and if the load was successful,
		1378	used as event model. If it fails to load AnyEvent will proceed with
		1379	auto detection and -probing.
		1380
		1381	This functionality might change in future versions.
		1382
		1383	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1384	could start your program like this:
		1385
		1386	PERL_ANYEVENT_MODEL=Perl perl ...
		1387
		1388	=item C<PERL_ANYEVENT_PROTOCOLS>
		1389
		1390	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1391	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1392	of auto probing).
		1393
		1394	Must be set to a comma-separated list of protocols or address families,
		1395	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1396	used, and preference will be given to protocols mentioned earlier in the
		1397	list.
		1398
		1399	This variable can effectively be used for denial-of-service attacks
		1400	against local programs (e.g. when setuid), although the impact is likely
		1401	small, as the program has to handle conenction and other failures anyways.
		1402
		1403	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1404	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1405	- only support IPv4, never try to resolve or contact IPv6
		1406	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1407	IPv6, but prefer IPv6 over IPv4.
		1408
		1409	=item C<PERL_ANYEVENT_EDNS0>
		1410
		1411	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1412	for DNS. This extension is generally useful to reduce DNS traffic, but
		1413	some (broken) firewalls drop such DNS packets, which is why it is off by
		1414	default.
		1415
		1416	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1417	EDNS0 in its DNS requests.
		1418
		1419	=item C<PERL_ANYEVENT_MAX_FORKS>
		1420
		1421	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1422	will create in parallel.
		1423
		1424	=back
865		1425
866	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1426	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
867		1427
868	This is an advanced topic that you do not normally need to use AnyEvent in	1428	This is an advanced topic that you do not normally need to use AnyEvent in
869	a module. This section is only of use to event loop authors who want to	1429	a module. This section is only of use to event loop authors who want to
…		…
903		1463
904	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1464	I<rxvt-unicode> also cheats a bit by not providing blocking access to
905	condition variables: code blocking while waiting for a condition will	1465	condition variables: code blocking while waiting for a condition will
906	C<die>. This still works with most modules/usages, and blocking calls must	1466	C<die>. This still works with most modules/usages, and blocking calls must
907	not be done in an interactive application, so it makes sense.	1467	not be done in an interactive application, so it makes sense.
908
909	=head1 ENVIRONMENT VARIABLES
910
911	The following environment variables are used by this module:
912
913	=over 4
914
915	=item C<PERL_ANYEVENT_VERBOSE>
916
917	By default, AnyEvent will be completely silent except in fatal
918	conditions. You can set this environment variable to make AnyEvent more
919	talkative.
920
921	When set to C<1> or higher, causes AnyEvent to warn about unexpected
922	conditions, such as not being able to load the event model specified by
923	C<PERL_ANYEVENT_MODEL>.
924
925	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
926	model it chooses.
927
928	=item C<PERL_ANYEVENT_MODEL>
929
930	This can be used to specify the event model to be used by AnyEvent, before
931	autodetection and -probing kicks in. It must be a string consisting
932	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
933	and the resulting module name is loaded and if the load was successful,
934	used as event model. If it fails to load AnyEvent will proceed with
935	autodetection and -probing.
936
937	This functionality might change in future versions.
938
939	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
940	could start your program like this:
941
942	PERL_ANYEVENT_MODEL=Perl perl ...
943
944	=back
945		1468
946	=head1 EXAMPLE PROGRAM	1469	=head1 EXAMPLE PROGRAM
947		1470
948	The following program uses an I/O watcher to read data from STDIN, a timer	1471	The following program uses an I/O watcher to read data from STDIN, a timer
949	to display a message once per second, and a condition variable to quit the	1472	to display a message once per second, and a condition variable to quit the
…		…
958	poll => 'r',	1481	poll => 'r',
959	cb => sub {	1482	cb => sub {
960	warn "io event <$_[0]>\n"; # will always output <r>	1483	warn "io event <$_[0]>\n"; # will always output <r>
961	chomp (my $input = <STDIN>); # read a line	1484	chomp (my $input = <STDIN>); # read a line
962	warn "read: $input\n"; # output what has been read	1485	warn "read: $input\n"; # output what has been read
963	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1486	$cv->send if $input =~ /^q/i; # quit program if /^q/i
964	},	1487	},
965	);	1488	);
966		1489
967	my $time_watcher; # can only be used once	1490	my $time_watcher; # can only be used once
968		1491
…		…
973	});	1496	});
974	}	1497	}
975		1498
976	new_timer; # create first timer	1499	new_timer; # create first timer
977		1500
978	$cv->wait; # wait until user enters /^q/i	1501	$cv->recv; # wait until user enters /^q/i
979		1502
980	=head1 REAL-WORLD EXAMPLE	1503	=head1 REAL-WORLD EXAMPLE
981		1504
982	Consider the L<Net::FCP> module. It features (among others) the following	1505	Consider the L<Net::FCP> module. It features (among others) the following
983	API calls, which are to freenet what HTTP GET requests are to http:	1506	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1033	syswrite $txn->{fh}, $txn->{request}	1556	syswrite $txn->{fh}, $txn->{request}
1034	or die "connection or write error";	1557	or die "connection or write error";
1035	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1558	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1036		1559
1037	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1560	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1038	result and signals any possible waiters that the request ahs finished:	1561	result and signals any possible waiters that the request has finished:
1039		1562
1040	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1563	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1041		1564
1042	if (end-of-file or data complete) {	1565	if (end-of-file or data complete) {
1043	$txn->{result} = $txn->{buf};	1566	$txn->{result} = $txn->{buf};
1044	$txn->{finished}->broadcast;	1567	$txn->{finished}->send;
1045	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1568	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1046	}	1569	}
1047		1570
1048	The C<result> method, finally, just waits for the finished signal (if the	1571	The C<result> method, finally, just waits for the finished signal (if the
1049	request was already finished, it doesn't wait, of course, and returns the	1572	request was already finished, it doesn't wait, of course, and returns the
1050	data:	1573	data:
1051		1574
1052	$txn->{finished}->wait;	1575	$txn->{finished}->recv;
1053	return $txn->{result};	1576	return $txn->{result};
1054		1577
1055	The actual code goes further and collects all errors (C<die>s, exceptions)	1578	The actual code goes further and collects all errors (C<die>s, exceptions)
1056	that occured during request processing. The C<result> method detects	1579	that occurred during request processing. The C<result> method detects
1057	whether an exception as thrown (it is stored inside the $txn object)	1580	whether an exception as thrown (it is stored inside the $txn object)
1058	and just throws the exception, which means connection errors and other	1581	and just throws the exception, which means connection errors and other
1059	problems get reported tot he code that tries to use the result, not in a	1582	problems get reported tot he code that tries to use the result, not in a
1060	random callback.	1583	random callback.
1061		1584
…		…
1092		1615
1093	my $quit = AnyEvent->condvar;	1616	my $quit = AnyEvent->condvar;
1094		1617
1095	$fcp->txn_client_get ($url)->cb (sub {	1618	$fcp->txn_client_get ($url)->cb (sub {
1096	...	1619	...
1097	$quit->broadcast;	1620	$quit->send;
1098	});	1621	});
1099		1622
1100	$quit->wait;	1623	$quit->recv;
1101		1624
1102		1625
1103	=head1 BENCHMARKS	1626	=head1 BENCHMARKS
1104		1627
1105	To give you an idea of the performance and overheads that AnyEvent adds	1628	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1107	of various event loops I prepared some benchmarks.	1630	of various event loops I prepared some benchmarks.
1108		1631
1109	=head2 BENCHMARKING ANYEVENT OVERHEAD	1632	=head2 BENCHMARKING ANYEVENT OVERHEAD
1110		1633
1111	Here is a benchmark of various supported event models used natively and	1634	Here is a benchmark of various supported event models used natively and
1112	through anyevent. The benchmark creates a lot of timers (with a zero	1635	through AnyEvent. The benchmark creates a lot of timers (with a zero
1113	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1636	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1114	which it is), lets them fire exactly once and destroys them again.	1637	which it is), lets them fire exactly once and destroys them again.
1115		1638
1116	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1639	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1117	distribution.	1640	distribution.
…		…
1134	all watchers, to avoid adding memory overhead. That means closure creation	1657	all watchers, to avoid adding memory overhead. That means closure creation
1135	and memory usage is not included in the figures.	1658	and memory usage is not included in the figures.
1136		1659
1137	I<invoke> is the time, in microseconds, used to invoke a simple	1660	I<invoke> is the time, in microseconds, used to invoke a simple
1138	callback. The callback simply counts down a Perl variable and after it was	1661	callback. The callback simply counts down a Perl variable and after it was
1139	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1662	invoked "watcher" times, it would C<< ->send >> a condvar once to
1140	signal the end of this phase.	1663	signal the end of this phase.
1141		1664
1142	I<destroy> is the time, in microseconds, that it takes to destroy a single	1665	I<destroy> is the time, in microseconds, that it takes to destroy a single
1143	watcher.	1666	watcher.
1144		1667
1145	=head3 Results	1668	=head3 Results
1146		1669
1147	name watchers bytes create invoke destroy comment	1670	name watchers bytes create invoke destroy comment
1148	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1671	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1149	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1672	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1150	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1673	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1151	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1674	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1152	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1675	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1153	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1676	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1154	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1677	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1155	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1678	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1156	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1679	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1157	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1680	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1158		1681
1159	=head3 Discussion	1682	=head3 Discussion
1160		1683
1161	The benchmark does I<not> measure scalability of the event loop very	1684	The benchmark does I<not> measure scalability of the event loop very
1162	well. For example, a select-based event loop (such as the pure perl one)	1685	well. For example, a select-based event loop (such as the pure perl one)
…		…
1240		1763
1241	=back	1764	=back
1242		1765
1243	=head2 BENCHMARKING THE LARGE SERVER CASE	1766	=head2 BENCHMARKING THE LARGE SERVER CASE
1244		1767
1245	This benchmark atcually benchmarks the event loop itself. It works by	1768	This benchmark actually benchmarks the event loop itself. It works by
1246	creating a number of "servers": each server consists of a socketpair, a	1769	creating a number of "servers": each server consists of a socket pair, a
1247	timeout watcher that gets reset on activity (but never fires), and an I/O	1770	timeout watcher that gets reset on activity (but never fires), and an I/O
1248	watcher waiting for input on one side of the socket. Each time the socket	1771	watcher waiting for input on one side of the socket. Each time the socket
1249	watcher reads a byte it will write that byte to a random other "server".	1772	watcher reads a byte it will write that byte to a random other "server".
1250		1773
1251	The effect is that there will be a lot of I/O watchers, only part of which	1774	The effect is that there will be a lot of I/O watchers, only part of which
1252	are active at any one point (so there is a constant number of active	1775	are active at any one point (so there is a constant number of active
1253	fds for each loop iterstaion, but which fds these are is random). The	1776	fds for each loop iteration, but which fds these are is random). The
1254	timeout is reset each time something is read because that reflects how	1777	timeout is reset each time something is read because that reflects how
1255	most timeouts work (and puts extra pressure on the event loops).	1778	most timeouts work (and puts extra pressure on the event loops).
1256		1779
1257	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1780	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1258	(1%) are active. This mirrors the activity of large servers with many	1781	(1%) are active. This mirrors the activity of large servers with many
1259	connections, most of which are idle at any one point in time.	1782	connections, most of which are idle at any one point in time.
1260		1783
1261	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1784	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1262	distribution.	1785	distribution.
…		…
1264	=head3 Explanation of the columns	1787	=head3 Explanation of the columns
1265		1788
1266	I<sockets> is the number of sockets, and twice the number of "servers" (as	1789	I<sockets> is the number of sockets, and twice the number of "servers" (as
1267	each server has a read and write socket end).	1790	each server has a read and write socket end).
1268		1791
1269	I<create> is the time it takes to create a socketpair (which is	1792	I<create> is the time it takes to create a socket pair (which is
1270	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1793	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1271		1794
1272	I<request>, the most important value, is the time it takes to handle a	1795	I<request>, the most important value, is the time it takes to handle a
1273	single "request", that is, reading the token from the pipe and forwarding	1796	single "request", that is, reading the token from the pipe and forwarding
1274	it to another server. This includes deleting the old timeout and creating	1797	it to another server. This includes deleting the old timeout and creating
…		…
1347	speed most when you have lots of watchers, not when you only have a few of	1870	speed most when you have lots of watchers, not when you only have a few of
1348	them).	1871	them).
1349		1872
1350	EV is again fastest.	1873	EV is again fastest.
1351		1874
1352	Perl again comes second. It is noticably faster than the C-based event	1875	Perl again comes second. It is noticeably faster than the C-based event
1353	loops Event and Glib, although the difference is too small to really	1876	loops Event and Glib, although the difference is too small to really
1354	matter.	1877	matter.
1355		1878
1356	POE also performs much better in this case, but is is still far behind the	1879	POE also performs much better in this case, but is is still far behind the
1357	others.	1880	others.
…		…
1362		1885
1363	=item * C-based event loops perform very well with small number of	1886	=item * C-based event loops perform very well with small number of
1364	watchers, as the management overhead dominates.	1887	watchers, as the management overhead dominates.
1365		1888
1366	=back	1889	=back
		1890
		1891
		1892	=head1 SIGNALS
		1893
		1894	AnyEvent currently installs handlers for these signals:
		1895
		1896	=over 4
		1897
		1898	=item SIGCHLD
		1899
		1900	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1901	emulation for event loops that do not support them natively. Also, some
		1902	event loops install a similar handler.
		1903
		1904	=item SIGPIPE
		1905
		1906	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1907	when AnyEvent gets loaded.
		1908
		1909	The rationale for this is that AnyEvent users usually do not really depend
		1910	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1911	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1912	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1913	some random socket.
		1914
		1915	The rationale for installing a no-op handler as opposed to ignoring it is
		1916	that this way, the handler will be restored to defaults on exec.
		1917
		1918	Feel free to install your own handler, or reset it to defaults.
		1919
		1920	=back
		1921
		1922	=cut
		1923
		1924	$SIG{PIPE} = sub { }
		1925	unless defined $SIG{PIPE};
1367		1926
1368		1927
1369	=head1 FORK	1928	=head1 FORK
1370		1929
1371	Most event libraries are not fork-safe. The ones who are usually are	1930	Most event libraries are not fork-safe. The ones who are usually are
…		…
1386	specified in the variable.	1945	specified in the variable.
1387		1946
1388	You can make AnyEvent completely ignore this variable by deleting it	1947	You can make AnyEvent completely ignore this variable by deleting it
1389	before the first watcher gets created, e.g. with a C<BEGIN> block:	1948	before the first watcher gets created, e.g. with a C<BEGIN> block:
1390		1949
1391	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1950	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1392		1951
1393	use AnyEvent;	1952	use AnyEvent;
		1953
		1954	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1955	be used to probe what backend is used and gain other information (which is
		1956	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1957	$ENV{PERL_ANYEGENT_STRICT}.
		1958
		1959
		1960	=head1 BUGS
		1961
		1962	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1963	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1964	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1965	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1966	pronounced).
1394		1967
1395		1968
1396	=head1 SEE ALSO	1969	=head1 SEE ALSO
1397		1970
1398	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1971	Utility functions: L<AnyEvent::Util>.
1399	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1972
		1973	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1400	L<Event::Lib>, L<Qt>, L<POE>.	1974	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1401		1975
1402	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1976	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1403	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1977	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1404	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1978	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1405	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1979	L<AnyEvent::Impl::POE>.
1406		1980
		1981	Non-blocking file handles, sockets, TCP clients and
		1982	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1983
		1984	Asynchronous DNS: L<AnyEvent::DNS>.
		1985
		1986	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1987
1407	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1988	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1408		1989
1409		1990
1410	=head1 AUTHOR	1991	=head1 AUTHOR
1411		1992
1412	Marc Lehmann <schmorp@schmorp.de>	1993	Marc Lehmann <schmorp@schmorp.de>
1413	http://home.schmorp.de/	1994	http://home.schmorp.de/
1414		1995
1415	=cut	1996	=cut
1416		1997
1417	1	1998	1
1418		1999

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