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Revision 1.214 by root, Mon Jun 22 11:57:05 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 and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70
71	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		100
91	=head1 DESCRIPTION	101	=head1 DESCRIPTION
92		102
93	L<AnyEvent> provides an identical interface to multiple event loops. This	103	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	104	allows module authors to utilise an event loop without forcing module
…		…
98	The interface itself is vaguely similar, but not identical to the L<Event>	108	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	109	module.
100		110
101	During the first call of any watcher-creation method, the module tries	111	During the first call of any watcher-creation method, the module tries
102	to detect the currently loaded event loop by probing whether one of the	112	to detect the currently loaded event loop by probing whether one of the
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	113	following modules is already loaded: L<EV>,
104	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	114	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
105	L<POE>. The first one found is used. If none are found, the module tries	115	L<POE>. The first one found is used. If none are found, the module tries
106	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	116	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
107	adaptor should always succeed) in the order given. The first one that can	117	adaptor should always succeed) in the order given. The first one that can
108	be successfully loaded will be used. If, after this, still none could be	118	be successfully loaded will be used. If, after this, still none could be
…		…
122	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
123	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
124		134
125	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
126	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
127	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
128		138
129	=head1 WATCHERS	139	=head1 WATCHERS
130		140
131	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
132	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
133	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
134		144
135	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
136	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
137	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
138	is in control).	148	is in control).
139		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
140	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
141	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
142	to it).	158	to it).
143		159
144	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.
…		…
146	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
147	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.
148		164
149	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
150		166
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
153	undef $w;	169	undef $w;
154	});	170	});
155		171
156	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,
157	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
158	declared.	174	declared.
159		175
160	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
161		177
162	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
163	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
164		180
165	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
166	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
167	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
168	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.
169	becomes ready.
170		192
171	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
172	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
173	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
174		196
…		…
178		200
179	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
180	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
181	handles.	203	handles.
182		204
183	Example:
184
185	# 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
186	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
187	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
188	warn "read: $input\n";	210	warn "read: $input\n";
189	undef $w;	211	undef $w;
190	});	212	});
…		…
200		222
201	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
202	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
203	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
204		226
205	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
206	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
207	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.
208		232
209	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.
210		236
211	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
212	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
213	warn "timeout\n";	240	warn "timeout\n";
214	});	241	});
215		242
216	# to cancel the timer:	243	# to cancel the timer:
217	undef $w;	244	undef $w;
218		245
219	Example 2:
220
221	# 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.
222	my $w;
223		247
224	my $cb = sub {
225	# cancel the old timer while creating a new one
226	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
227	};	250	};
228
229	# start the "loop" by creating the first watcher
230	$w = AnyEvent->timer (after => 0.5, cb => $cb);
231		251
232	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
233		253
234	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
235	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
…		…
247	timers.	267	timers.
248		268
249	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	270	AnyEvent API.
251		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
252	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
253		351
254	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
255	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
256	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
257		355
258	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
261		359
262	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
264	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,
265	but it is guarenteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
266		364
267	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
268	between multiple watchers.	366	between multiple watchers.
269		367
270	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
277	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
278		376
279	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.
280		378
281	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
282	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
283	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
284	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
285	and exit status (as returned by waitpid), so unlike other watcher types,	383
286	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).
287		392
288	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
289	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
290	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
291		396
…		…
297	AnyEvent program, you I<have> to create at least one watcher before you	402	AnyEvent program, you I<have> to create at least one watcher before you
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	403	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
299		404
300	Example: fork a process and wait for it	405	Example: fork a process and wait for it
301		406
302	my $done = AnyEvent->condvar;	407	my $done = AnyEvent->condvar;
303		408
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	409	my $pid = fork or exit 5;
307		410
308	my $w = AnyEvent->child (	411	my $w = AnyEvent->child (
309	pid => $pid,	412	pid => $pid,
310	cb => sub {	413	cb => sub {
311	my ($pid, $status) = @_;	414	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	415	warn "pid $pid exited with status $status";
313	$done->broadcast;	416	$done->send;
314	},	417	},
315	);	418	);
316		419
317	# do something else, then wait for process exit	420	# do something else, then wait for process exit
318	$done->wait;	421	$done->recv;
		422
		423	=head2 IDLE WATCHERS
		424
		425	Sometimes there is a need to do something, but it is not so important
		426	to do it instantly, but only when there is nothing better to do. This
		427	"nothing better to do" is usually defined to be "no other events need
		428	attention by the event loop".
		429
		430	Idle watchers ideally get invoked when the event loop has nothing
		431	better to do, just before it would block the process to wait for new
		432	events. Instead of blocking, the idle watcher is invoked.
		433
		434	Most event loops unfortunately do not really support idle watchers (only
		435	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		436	will simply call the callback "from time to time".
		437
		438	Example: read lines from STDIN, but only process them when the
		439	program is otherwise idle:
		440
		441	my @lines; # read data
		442	my $idle_w;
		443	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		444	push @lines, scalar <STDIN>;
		445
		446	# start an idle watcher, if not already done
		447	$idle_w ||= AnyEvent->idle (cb => sub {
		448	# handle only one line, when there are lines left
		449	if (my $line = shift @lines) {
		450	print "handled when idle: $line";
		451	} else {
		452	# otherwise disable the idle watcher again
		453	undef $idle_w;
		454	}
		455	});
		456	});
319		457
320	=head2 CONDITION VARIABLES	458	=head2 CONDITION VARIABLES
321		459
		460	If you are familiar with some event loops you will know that all of them
		461	require you to run some blocking "loop", "run" or similar function that
		462	will actively watch for new events and call your callbacks.
		463
		464	AnyEvent is different, it expects somebody else to run the event loop and
		465	will only block when necessary (usually when told by the user).
		466
		467	The instrument to do that is called a "condition variable", so called
		468	because they represent a condition that must become true.
		469
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	470	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	471	>> method, usually without arguments. The only argument pair allowed is
324		472
325	A condition variable waits for a condition - precisely that the C<<	473	C<cb>, which specifies a callback to be called when the condition variable
326	->broadcast >> method has been called.	474	becomes true, with the condition variable as the first argument (but not
		475	the results).
327		476
328	They are very useful to signal that a condition has been fulfilled, for	477	After creation, the condition variable is "false" until it becomes "true"
		478	by calling the C<send> method (or calling the condition variable as if it
		479	were a callback, read about the caveats in the description for the C<<
		480	->send >> method).
		481
		482	Condition variables are similar to callbacks, except that you can
		483	optionally wait for them. They can also be called merge points - points
		484	in time where multiple outstanding events have been processed. And yet
		485	another way to call them is transactions - each condition variable can be
		486	used to represent a transaction, which finishes at some point and delivers
		487	a result.
		488
		489	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	490	for example, if you write a module that does asynchronous http requests,
330	then a condition variable would be the ideal candidate to signal the	491	then a condition variable would be the ideal candidate to signal the
331	availability of results.	492	availability of results. The user can either act when the callback is
		493	called or can synchronously C<< ->recv >> for the results.
332		494
333	You can also use condition variables to block your main program until	495	You can also use them to simulate traditional event loops - for example,
334	an event occurs - for example, you could C<< ->wait >> in your main	496	you can block your main program until an event occurs - for example, you
335	program until the user clicks the Quit button in your app, which would C<<	497	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	498	button of your app, which would C<< ->send >> the "quit" event.
337		499
338	Note that condition variables recurse into the event loop - if you have	500	Note that condition variables recurse into the event loop - if you have
339	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	501	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	502	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	503	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	504	as this asks for trouble.
343		505
344	This object has two methods:	506	Condition variables are represented by hash refs in perl, and the keys
		507	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		508	easy (it is often useful to build your own transaction class on top of
		509	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		510	it's C<new> method in your own C<new> method.
		511
		512	There are two "sides" to a condition variable - the "producer side" which
		513	eventually calls C<< -> send >>, and the "consumer side", which waits
		514	for the send to occur.
		515
		516	Example: wait for a timer.
		517
		518	# wait till the result is ready
		519	my $result_ready = AnyEvent->condvar;
		520
		521	# do something such as adding a timer
		522	# or socket watcher the calls $result_ready->send
		523	# when the "result" is ready.
		524	# in this case, we simply use a timer:
		525	my $w = AnyEvent->timer (
		526	after => 1,
		527	cb => sub { $result_ready->send },
		528	);
		529
		530	# this "blocks" (while handling events) till the callback
		531	# calls send
		532	$result_ready->recv;
		533
		534	Example: wait for a timer, but take advantage of the fact that
		535	condition variables are also code references.
		536
		537	my $done = AnyEvent->condvar;
		538	my $delay = AnyEvent->timer (after => 5, cb => $done);
		539	$done->recv;
		540
		541	Example: Imagine an API that returns a condvar and doesn't support
		542	callbacks. This is how you make a synchronous call, for example from
		543	the main program:
		544
		545	use AnyEvent::CouchDB;
		546
		547	...
		548
		549	my @info = $couchdb->info->recv;
		550
		551	And this is how you would just ste a callback to be called whenever the
		552	results are available:
		553
		554	$couchdb->info->cb (sub {
		555	my @info = $_[0]->recv;
		556	});
		557
		558	=head3 METHODS FOR PRODUCERS
		559
		560	These methods should only be used by the producing side, i.e. the
		561	code/module that eventually sends the signal. Note that it is also
		562	the producer side which creates the condvar in most cases, but it isn't
		563	uncommon for the consumer to create it as well.
345		564
346	=over 4	565	=over 4
347		566
		567	=item $cv->send (...)
		568
		569	Flag the condition as ready - a running C<< ->recv >> and all further
		570	calls to C<recv> will (eventually) return after this method has been
		571	called. If nobody is waiting the send will be remembered.
		572
		573	If a callback has been set on the condition variable, it is called
		574	immediately from within send.
		575
		576	Any arguments passed to the C<send> call will be returned by all
		577	future C<< ->recv >> calls.
		578
		579	Condition variables are overloaded so one can call them directly
		580	(as a code reference). Calling them directly is the same as calling
		581	C<send>. Note, however, that many C-based event loops do not handle
		582	overloading, so as tempting as it may be, passing a condition variable
		583	instead of a callback does not work. Both the pure perl and EV loops
		584	support overloading, however, as well as all functions that use perl to
		585	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		586	example).
		587
		588	=item $cv->croak ($error)
		589
		590	Similar to send, but causes all call's to C<< ->recv >> to invoke
		591	C<Carp::croak> with the given error message/object/scalar.
		592
		593	This can be used to signal any errors to the condition variable
		594	user/consumer.
		595
		596	=item $cv->begin ([group callback])
		597
348	=item $cv->wait	598	=item $cv->end
349		599
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	600	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		601
		602	These two methods can be used to combine many transactions/events into
		603	one. For example, a function that pings many hosts in parallel might want
		604	to use a condition variable for the whole process.
		605
		606	Every call to C<< ->begin >> will increment a counter, and every call to
		607	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		608	>>, the (last) callback passed to C<begin> will be executed. That callback
		609	is I<supposed> to call C<< ->send >>, but that is not required. If no
		610	callback was set, C<send> will be called without any arguments.
		611
		612	Let's clarify this with the ping example:
		613
		614	my $cv = AnyEvent->condvar;
		615
		616	my %result;
		617	$cv->begin (sub { $cv->send (\%result) });
		618
		619	for my $host (@list_of_hosts) {
		620	$cv->begin;
		621	ping_host_then_call_callback $host, sub {
		622	$result{$host} = ...;
		623	$cv->end;
		624	};
		625	}
		626
		627	$cv->end;
		628
		629	This code fragment supposedly pings a number of hosts and calls
		630	C<send> after results for all then have have been gathered - in any
		631	order. To achieve this, the code issues a call to C<begin> when it starts
		632	each ping request and calls C<end> when it has received some result for
		633	it. Since C<begin> and C<end> only maintain a counter, the order in which
		634	results arrive is not relevant.
		635
		636	There is an additional bracketing call to C<begin> and C<end> outside the
		637	loop, which serves two important purposes: first, it sets the callback
		638	to be called once the counter reaches C<0>, and second, it ensures that
		639	C<send> is called even when C<no> hosts are being pinged (the loop
		640	doesn't execute once).
		641
		642	This is the general pattern when you "fan out" into multiple subrequests:
		643	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		644	is called at least once, and then, for each subrequest you start, call
		645	C<begin> and for each subrequest you finish, call C<end>.
		646
		647	=back
		648
		649	=head3 METHODS FOR CONSUMERS
		650
		651	These methods should only be used by the consuming side, i.e. the
		652	code awaits the condition.
		653
		654	=over 4
		655
		656	=item $cv->recv
		657
		658	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	659	>> methods have been called on c<$cv>, while servicing other watchers
		660	normally.
352		661
353	You can only wait once on a condition - additional calls will return	662	You can only wait once on a condition - additional calls are valid but
354	immediately.	663	will return immediately.
		664
		665	If an error condition has been set by calling C<< ->croak >>, then this
		666	function will call C<croak>.
		667
		668	In list context, all parameters passed to C<send> will be returned,
		669	in scalar context only the first one will be returned.
355		670
356	Not all event models support a blocking wait - some die in that case	671	Not all event models support a blocking wait - some die in that case
357	(programs might want to do that to stay interactive), so I<if you are	672	(programs might want to do that to stay interactive), so I<if you are
358	using this from a module, never require a blocking wait>, but let the	673	using this from a module, never require a blocking wait>, but let the
359	caller decide whether the call will block or not (for example, by coupling	674	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting	675	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,	676	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).	677	while still supporting blocking waits if the caller so desires).
363		678
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot	679	Another reason I<never> to C<< ->recv >> in a module is that you cannot
365	sensibly have two C<< ->wait >>'s in parallel, as that would require	680	sensibly have two C<< ->recv >>'s in parallel, as that would require
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	681	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	682	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		683
371	=item $cv->broadcast	684	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		685	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		686	versions and also integrates coroutines into AnyEvent, making blocking
		687	C<< ->recv >> calls perfectly safe as long as they are done from another
		688	coroutine (one that doesn't run the event loop).
372		689
373	Flag the condition as ready - a running C<< ->wait >> and all further	690	You can ensure that C<< -recv >> never blocks by setting a callback and
374	calls to C<wait> will (eventually) return after this method has been	691	only calling C<< ->recv >> from within that callback (or at a later
375	called. If nobody is waiting the broadcast will be remembered..	692	time). This will work even when the event loop does not support blocking
		693	waits otherwise.
		694
		695	=item $bool = $cv->ready
		696
		697	Returns true when the condition is "true", i.e. whether C<send> or
		698	C<croak> have been called.
		699
		700	=item $cb = $cv->cb ($cb->($cv))
		701
		702	This is a mutator function that returns the callback set and optionally
		703	replaces it before doing so.
		704
		705	The callback will be called when the condition becomes "true", i.e. when
		706	C<send> or C<croak> are called, with the only argument being the condition
		707	variable itself. Calling C<recv> inside the callback or at any later time
		708	is guaranteed not to block.
376		709
377	=back	710	=back
378
379	Example:
380
381	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;
383
384	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392
393	# this "blocks" (while handling events) till the watcher
394	# calls broadcast
395	$result_ready->wait;
396		711
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	712	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		713
399	=over 4	714	=over 4
400		715
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	721	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	722	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		723
409	The known classes so far are:	724	The known classes so far are:
410		725
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	726	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	727	AnyEvent::Impl::Event based on Event, second best choice.
		728	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	729	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	730	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	731	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	732	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	733	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		734
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	747	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	748	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	749	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	750	runtime.
438		751
		752	=item $guard = AnyEvent::post_detect { BLOCK }
		753
		754	Arranges for the code block to be executed as soon as the event model is
		755	autodetected (or immediately if this has already happened).
		756
		757	If called in scalar or list context, then it creates and returns an object
		758	that automatically removes the callback again when it is destroyed. See
		759	L<Coro::BDB> for a case where this is useful.
		760
		761	=item @AnyEvent::post_detect
		762
		763	If there are any code references in this array (you can C<push> to it
		764	before or after loading AnyEvent), then they will called directly after
		765	the event loop has been chosen.
		766
		767	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		768	if it contains a true value then the event loop has already been detected,
		769	and the array will be ignored.
		770
		771	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		772
439	=back	773	=back
440		774
441	=head1 WHAT TO DO IN A MODULE	775	=head1 WHAT TO DO IN A MODULE
442		776
443	As a module author, you should C<use AnyEvent> and call AnyEvent methods	777	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	780	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	781	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	782	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	783	to load the event module first.
450		784
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	785	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	786	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	787	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	788	events is to stay interactive.
455		789
456	It is fine, however, to call C<< ->wait >> when the user of your module	790	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	791	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	792	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	793	freely, as the user of your module knows what she is doing. always).
460		794
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	795	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		796
463	There will always be a single main program - the only place that should	797	There will always be a single main program - the only place that should
…		…
465		799
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	800	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	801	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	802	decide which implementation to chose if some module relies on it.
469		803
470	If the main program relies on a specific event model. For example, in	804	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	805	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	806	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	807	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	808	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	809	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	810	might chose the wrong one unless you load the correct one yourself.
477		811
478	You can chose to use a rather inefficient pure-perl implementation by	812	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	813	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	814	everywhere, but letting AnyEvent chose the model is generally better.
		815
		816	=head2 MAINLOOP EMULATION
		817
		818	Sometimes (often for short test scripts, or even standalone programs who
		819	only want to use AnyEvent), you do not want to run a specific event loop.
		820
		821	In that case, you can use a condition variable like this:
		822
		823	AnyEvent->condvar->recv;
		824
		825	This has the effect of entering the event loop and looping forever.
		826
		827	Note that usually your program has some exit condition, in which case
		828	it is better to use the "traditional" approach of storing a condition
		829	variable somewhere, waiting for it, and sending it when the program should
		830	exit cleanly.
		831
		832
		833	=head1 OTHER MODULES
		834
		835	The following is a non-exhaustive list of additional modules that use
		836	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		837	in the same program. Some of the modules come with AnyEvent, some are
		838	available via CPAN.
		839
		840	=over 4
		841
		842	=item L<AnyEvent::Util>
		843
		844	Contains various utility functions that replace often-used but blocking
		845	functions such as C<inet_aton> by event-/callback-based versions.
		846
		847	=item L<AnyEvent::Socket>
		848
		849	Provides various utility functions for (internet protocol) sockets,
		850	addresses and name resolution. Also functions to create non-blocking tcp
		851	connections or tcp servers, with IPv6 and SRV record support and more.
		852
		853	=item L<AnyEvent::Handle>
		854
		855	Provide read and write buffers, manages watchers for reads and writes,
		856	supports raw and formatted I/O, I/O queued and fully transparent and
		857	non-blocking SSL/TLS.
		858
		859	=item L<AnyEvent::DNS>
		860
		861	Provides rich asynchronous DNS resolver capabilities.
		862
		863	=item L<AnyEvent::HTTP>
		864
		865	A simple-to-use HTTP library that is capable of making a lot of concurrent
		866	HTTP requests.
		867
		868	=item L<AnyEvent::HTTPD>
		869
		870	Provides a simple web application server framework.
		871
		872	=item L<AnyEvent::FastPing>
		873
		874	The fastest ping in the west.
		875
		876	=item L<AnyEvent::DBI>
		877
		878	Executes L<DBI> requests asynchronously in a proxy process.
		879
		880	=item L<AnyEvent::AIO>
		881
		882	Truly asynchronous I/O, should be in the toolbox of every event
		883	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		884	together.
		885
		886	=item L<AnyEvent::BDB>
		887
		888	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		889	L<BDB> and AnyEvent together.
		890
		891	=item L<AnyEvent::GPSD>
		892
		893	A non-blocking interface to gpsd, a daemon delivering GPS information.
		894
		895	=item L<AnyEvent::IGS>
		896
		897	A non-blocking interface to the Internet Go Server protocol (used by
		898	L<App::IGS>).
		899
		900	=item L<AnyEvent::IRC>
		901
		902	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		903
		904	=item L<Net::XMPP2>
		905
		906	AnyEvent based XMPP (Jabber protocol) module family.
		907
		908	=item L<Net::FCP>
		909
		910	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		911	of AnyEvent.
		912
		913	=item L<Event::ExecFlow>
		914
		915	High level API for event-based execution flow control.
		916
		917	=item L<Coro>
		918
		919	Has special support for AnyEvent via L<Coro::AnyEvent>.
		920
		921	=item L<IO::Lambda>
		922
		923	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		924
		925	=back
481		926
482	=cut	927	=cut
483		928
484	package AnyEvent;	929	package AnyEvent;
485		930
486	no warnings;	931	no warnings;
487	use strict;	932	use strict qw(vars subs);
488		933
489	use Carp;	934	use Carp;
490		935
491	our $VERSION = '3.3';	936	our $VERSION = 4.411;
492	our $MODEL;	937	our $MODEL;
493		938
494	our $AUTOLOAD;	939	our $AUTOLOAD;
495	our @ISA;	940	our @ISA;
496		941
		942	our @REGISTRY;
		943
		944	our $WIN32;
		945
		946	BEGIN {
		947	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		948	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		949
		950	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		951	if ${^TAINT};
		952	}
		953
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	954	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498		955
499	our @REGISTRY;	956	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		957
		958	{
		959	my $idx;
		960	$PROTOCOL{$_} = ++$idx
		961	for reverse split /\s*,\s*/,
		962	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		963	}
500		964
501	my @models = (	965	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	966	[EV:: => AnyEvent::Impl::EV::],
505	[Event:: => AnyEvent::Impl::Event::],	967	[Event:: => AnyEvent::Impl::Event::],
506	[Glib:: => AnyEvent::Impl::Glib::],
507	[Tk:: => AnyEvent::Impl::Tk::],
508	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	968	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	969	# everything below here will not be autoprobed
		970	# as the pureperl backend should work everywhere
		971	# and is usually faster
		972	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		973	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	974	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	975	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	976	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		977	[Wx:: => AnyEvent::Impl::POE::],
		978	[Prima:: => AnyEvent::Impl::POE::],
515	);	979	);
516		980
517	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	981	our %method = map +($_ => 1),
		982	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		983
		984	our @post_detect;
		985
		986	sub post_detect(&) {
		987	my ($cb) = @_;
		988
		989	if ($MODEL) {
		990	$cb->();
		991
		992	1
		993	} else {
		994	push @post_detect, $cb;
		995
		996	defined wantarray
		997	? bless \$cb, "AnyEvent::Util::postdetect"
		998	: ()
		999	}
		1000	}
		1001
		1002	sub AnyEvent::Util::postdetect::DESTROY {
		1003	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1004	}
518		1005
519	sub detect() {	1006	sub detect() {
520	unless ($MODEL) {	1007	unless ($MODEL) {
521	no strict 'refs';	1008	no strict 'refs';
		1009	local $SIG{__DIE__};
522		1010
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1011	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
524	my $model = "AnyEvent::Impl::$1";	1012	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	1013	if (eval "require $model") {
526	$MODEL = $model;	1014	$MODEL = $model;
…		…
556	last;	1044	last;
557	}	1045	}
558	}	1046	}
559		1047
560	$MODEL	1048	$MODEL
561	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1049	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
562	}	1050	}
563	}	1051	}
564		1052
		1053	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1054
565	unshift @ISA, $MODEL;	1055	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1056
		1057	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1058
		1059	(shift @post_detect)->() while @post_detect;
567	}	1060	}
568		1061
569	$MODEL	1062	$MODEL
570	}	1063	}
571		1064
…		…
579		1072
580	my $class = shift;	1073	my $class = shift;
581	$class->$func (@_);	1074	$class->$func (@_);
582	}	1075	}
583		1076
		1077	# utility function to dup a filehandle. this is used by many backends
		1078	# to support binding more than one watcher per filehandle (they usually
		1079	# allow only one watcher per fd, so we dup it to get a different one).
		1080	sub _dupfh($$$$) {
		1081	my ($poll, $fh, $r, $w) = @_;
		1082
		1083	# cygwin requires the fh mode to be matching, unix doesn't
		1084	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1085	: $poll eq "w" ? ($w, ">")
		1086	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1087
		1088	open my $fh2, "$mode&" . fileno $fh
		1089	or die "cannot dup() filehandle: $!,";
		1090
		1091	# we assume CLOEXEC is already set by perl in all important cases
		1092
		1093	($fh2, $rw)
		1094	}
		1095
584	package AnyEvent::Base;	1096	package AnyEvent::Base;
585		1097
		1098	# default implementations for many methods
		1099
		1100	BEGIN {
		1101	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1102	*_time = \&Time::HiRes::time;
		1103	# if (eval "use POSIX (); (POSIX::times())...
		1104	} else {
		1105	*_time = sub { time }; # epic fail
		1106	}
		1107	}
		1108
		1109	sub time { _time }
		1110	sub now { _time }
		1111	sub now_update { }
		1112
586	# default implementation for ->condvar, ->wait, ->broadcast	1113	# default implementation for ->condvar
587		1114
588	sub condvar {	1115	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	1116	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
590	}
591
592	sub AnyEvent::Base::CondVar::broadcast {
593	${$_[0]}++;
594	}
595
596	sub AnyEvent::Base::CondVar::wait {
597	AnyEvent->one_event while !${$_[0]};
598	}	1117	}
599		1118
600	# default implementation for ->signal	1119	# default implementation for ->signal
601		1120
602	our %SIG_CB;	1121	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1122
		1123	sub _signal_exec {
		1124	sysread $SIGPIPE_R, my $dummy, 4;
		1125
		1126	while (%SIG_EV) {
		1127	for (keys %SIG_EV) {
		1128	delete $SIG_EV{$_};
		1129	$_->() for values %{ $SIG_CB{$_} || {} };
		1130	}
		1131	}
		1132	}
603		1133
604	sub signal {	1134	sub signal {
605	my (undef, %arg) = @_;	1135	my (undef, %arg) = @_;
606		1136
		1137	unless ($SIGPIPE_R) {
		1138	require Fcntl;
		1139
		1140	if (AnyEvent::WIN32) {
		1141	require AnyEvent::Util;
		1142
		1143	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1144	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1145	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1146	} else {
		1147	pipe $SIGPIPE_R, $SIGPIPE_W;
		1148	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1149	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1150
		1151	# not strictly required, as $^F is normally 2, but let's make sure...
		1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1154	}
		1155
		1156	$SIGPIPE_R
		1157	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1158
		1159	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1160	}
		1161
607	my $signal = uc $arg{signal}	1162	my $signal = uc $arg{signal}
608	or Carp::croak "required option 'signal' is missing";	1163	or Carp::croak "required option 'signal' is missing";
609		1164
610	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1165	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
611	$SIG{$signal} ||= sub {	1166	$SIG{$signal} ||= sub {
612	$_->() for values %{ $SIG_CB{$signal} || {} };	1167	local $!;
		1168	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1169	undef $SIG_EV{$signal};
613	};	1170	};
614		1171
615	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1172	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
616	}	1173	}
617		1174
618	sub AnyEvent::Base::Signal::DESTROY {	1175	sub AnyEvent::Base::signal::DESTROY {
619	my ($signal, $cb) = @{$_[0]};	1176	my ($signal, $cb) = @{$_[0]};
620		1177
621	delete $SIG_CB{$signal}{$cb};	1178	delete $SIG_CB{$signal}{$cb};
622		1179
		1180	# delete doesn't work with older perls - they then
		1181	# print weird messages, or just unconditionally exit
		1182	# instead of getting the default action.
623	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1183	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
624	}	1184	}
625		1185
626	# default implementation for ->child	1186	# default implementation for ->child
627		1187
628	our %PID_CB;	1188	our %PID_CB;
629	our $CHLD_W;	1189	our $CHLD_W;
630	our $CHLD_DELAY_W;	1190	our $CHLD_DELAY_W;
631	our $PID_IDLE;
632	our $WNOHANG;	1191	our $WNOHANG;
633		1192
634	sub _child_wait {	1193	sub _sigchld {
635	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1194	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
636	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1195	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
637	(values %{ $PID_CB{0} || {} });	1196	(values %{ $PID_CB{0} || {} });
638	}	1197	}
639
640	undef $PID_IDLE;
641	}
642
643	sub _sigchld {
644	# make sure we deliver these changes "synchronous" with the event loop.
645	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
646	undef $CHLD_DELAY_W;
647	&_child_wait;
648	});
649	}	1198	}
650		1199
651	sub child {	1200	sub child {
652	my (undef, %arg) = @_;	1201	my (undef, %arg) = @_;
653		1202
654	defined (my $pid = $arg{pid} + 0)	1203	defined (my $pid = $arg{pid} + 0)
655	or Carp::croak "required option 'pid' is missing";	1204	or Carp::croak "required option 'pid' is missing";
656		1205
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1206	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1207
659	unless ($WNOHANG) {
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1208	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
661	}
662		1209
663	unless ($CHLD_W) {	1210	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1211	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
665	# child could be a zombie already, so make at least one round	1212	# child could be a zombie already, so make at least one round
666	&_sigchld;	1213	&_sigchld;
667	}	1214	}
668		1215
669	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1216	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
670	}	1217	}
671		1218
672	sub AnyEvent::Base::Child::DESTROY {	1219	sub AnyEvent::Base::child::DESTROY {
673	my ($pid, $cb) = @{$_[0]};	1220	my ($pid, $cb) = @{$_[0]};
674		1221
675	delete $PID_CB{$pid}{$cb};	1222	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1223	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1224
678	undef $CHLD_W unless keys %PID_CB;	1225	undef $CHLD_W unless keys %PID_CB;
679	}	1226	}
		1227
		1228	# idle emulation is done by simply using a timer, regardless
		1229	# of whether the process is idle or not, and not letting
		1230	# the callback use more than 50% of the time.
		1231	sub idle {
		1232	my (undef, %arg) = @_;
		1233
		1234	my ($cb, $w, $rcb) = $arg{cb};
		1235
		1236	$rcb = sub {
		1237	if ($cb) {
		1238	$w = _time;
		1239	&$cb;
		1240	$w = _time - $w;
		1241
		1242	# never use more then 50% of the time for the idle watcher,
		1243	# within some limits
		1244	$w = 0.0001 if $w < 0.0001;
		1245	$w = 5 if $w > 5;
		1246
		1247	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1248	} else {
		1249	# clean up...
		1250	undef $w;
		1251	undef $rcb;
		1252	}
		1253	};
		1254
		1255	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1256
		1257	bless \\$cb, "AnyEvent::Base::idle"
		1258	}
		1259
		1260	sub AnyEvent::Base::idle::DESTROY {
		1261	undef $${$_[0]};
		1262	}
		1263
		1264	package AnyEvent::CondVar;
		1265
		1266	our @ISA = AnyEvent::CondVar::Base::;
		1267
		1268	package AnyEvent::CondVar::Base;
		1269
		1270	use overload
		1271	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1272	fallback => 1;
		1273
		1274	sub _send {
		1275	# nop
		1276	}
		1277
		1278	sub send {
		1279	my $cv = shift;
		1280	$cv->{_ae_sent} = [@_];
		1281	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1282	$cv->_send;
		1283	}
		1284
		1285	sub croak {
		1286	$_[0]{_ae_croak} = $_[1];
		1287	$_[0]->send;
		1288	}
		1289
		1290	sub ready {
		1291	$_[0]{_ae_sent}
		1292	}
		1293
		1294	sub _wait {
		1295	AnyEvent->one_event while !$_[0]{_ae_sent};
		1296	}
		1297
		1298	sub recv {
		1299	$_[0]->_wait;
		1300
		1301	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1302	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1303	}
		1304
		1305	sub cb {
		1306	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1307	$_[0]{_ae_cb}
		1308	}
		1309
		1310	sub begin {
		1311	++$_[0]{_ae_counter};
		1312	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1313	}
		1314
		1315	sub end {
		1316	return if --$_[0]{_ae_counter};
		1317	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1318	}
		1319
		1320	# undocumented/compatibility with pre-3.4
		1321	*broadcast = \&send;
		1322	*wait = \&_wait;
		1323
		1324	=head1 ERROR AND EXCEPTION HANDLING
		1325
		1326	In general, AnyEvent does not do any error handling - it relies on the
		1327	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1328	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1329	checking of all AnyEvent methods, however, which is highly useful during
		1330	development.
		1331
		1332	As for exception handling (i.e. runtime errors and exceptions thrown while
		1333	executing a callback), this is not only highly event-loop specific, but
		1334	also not in any way wrapped by this module, as this is the job of the main
		1335	program.
		1336
		1337	The pure perl event loop simply re-throws the exception (usually
		1338	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1339	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1340	so on.
		1341
		1342	=head1 ENVIRONMENT VARIABLES
		1343
		1344	The following environment variables are used by this module or its
		1345	submodules.
		1346
		1347	Note that AnyEvent will remove I<all> environment variables starting with
		1348	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1349	enabled.
		1350
		1351	=over 4
		1352
		1353	=item C<PERL_ANYEVENT_VERBOSE>
		1354
		1355	By default, AnyEvent will be completely silent except in fatal
		1356	conditions. You can set this environment variable to make AnyEvent more
		1357	talkative.
		1358
		1359	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1360	conditions, such as not being able to load the event model specified by
		1361	C<PERL_ANYEVENT_MODEL>.
		1362
		1363	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1364	model it chooses.
		1365
		1366	=item C<PERL_ANYEVENT_STRICT>
		1367
		1368	AnyEvent does not do much argument checking by default, as thorough
		1369	argument checking is very costly. Setting this variable to a true value
		1370	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1371	check the arguments passed to most method calls. If it finds any problems
		1372	it will croak.
		1373
		1374	In other words, enables "strict" mode.
		1375
		1376	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1377	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1378	developing programs can be very useful, however.
		1379
		1380	=item C<PERL_ANYEVENT_MODEL>
		1381
		1382	This can be used to specify the event model to be used by AnyEvent, before
		1383	auto detection and -probing kicks in. It must be a string consisting
		1384	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1385	and the resulting module name is loaded and if the load was successful,
		1386	used as event model. If it fails to load AnyEvent will proceed with
		1387	auto detection and -probing.
		1388
		1389	This functionality might change in future versions.
		1390
		1391	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1392	could start your program like this:
		1393
		1394	PERL_ANYEVENT_MODEL=Perl perl ...
		1395
		1396	=item C<PERL_ANYEVENT_PROTOCOLS>
		1397
		1398	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1399	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1400	of auto probing).
		1401
		1402	Must be set to a comma-separated list of protocols or address families,
		1403	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1404	used, and preference will be given to protocols mentioned earlier in the
		1405	list.
		1406
		1407	This variable can effectively be used for denial-of-service attacks
		1408	against local programs (e.g. when setuid), although the impact is likely
		1409	small, as the program has to handle conenction and other failures anyways.
		1410
		1411	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1412	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1413	- only support IPv4, never try to resolve or contact IPv6
		1414	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1415	IPv6, but prefer IPv6 over IPv4.
		1416
		1417	=item C<PERL_ANYEVENT_EDNS0>
		1418
		1419	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1420	for DNS. This extension is generally useful to reduce DNS traffic, but
		1421	some (broken) firewalls drop such DNS packets, which is why it is off by
		1422	default.
		1423
		1424	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1425	EDNS0 in its DNS requests.
		1426
		1427	=item C<PERL_ANYEVENT_MAX_FORKS>
		1428
		1429	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1430	will create in parallel.
		1431
		1432	=back
680		1433
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1434	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1435
683	This is an advanced topic that you do not normally need to use AnyEvent in	1436	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1437	a module. This section is only of use to event loop authors who want to
…		…
718		1471
719	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1472	I<rxvt-unicode> also cheats a bit by not providing blocking access to
720	condition variables: code blocking while waiting for a condition will	1473	condition variables: code blocking while waiting for a condition will
721	C<die>. This still works with most modules/usages, and blocking calls must	1474	C<die>. This still works with most modules/usages, and blocking calls must
722	not be done in an interactive application, so it makes sense.	1475	not be done in an interactive application, so it makes sense.
723
724	=head1 ENVIRONMENT VARIABLES
725
726	The following environment variables are used by this module:
727
728	=over 4
729
730	=item C<PERL_ANYEVENT_VERBOSE>
731
732	By default, AnyEvent will be completely silent except in fatal
733	conditions. You can set this environment variable to make AnyEvent more
734	talkative.
735
736	When set to C<1> or higher, causes AnyEvent to warn about unexpected
737	conditions, such as not being able to load the event model specified by
738	C<PERL_ANYEVENT_MODEL>.
739
740	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
741	model it chooses.
742
743	=item C<PERL_ANYEVENT_MODEL>
744
745	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.
751
752	This functionality might change in future versions.
753
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:
756
757	PERL_ANYEVENT_MODEL=Perl perl ...
758
759	=back
760		1476
761	=head1 EXAMPLE PROGRAM	1477	=head1 EXAMPLE PROGRAM
762		1478
763	The following program uses an I/O watcher to read data from STDIN, a timer	1479	The following program uses an I/O watcher to read data from STDIN, a timer
764	to display a message once per second, and a condition variable to quit the	1480	to display a message once per second, and a condition variable to quit the
…		…
773	poll => 'r',	1489	poll => 'r',
774	cb => sub {	1490	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1491	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1492	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1493	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1494	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1495	},
780	);	1496	);
781		1497
782	my $time_watcher; # can only be used once	1498	my $time_watcher; # can only be used once
783		1499
…		…
788	});	1504	});
789	}	1505	}
790		1506
791	new_timer; # create first timer	1507	new_timer; # create first timer
792		1508
793	$cv->wait; # wait until user enters /^q/i	1509	$cv->recv; # wait until user enters /^q/i
794		1510
795	=head1 REAL-WORLD EXAMPLE	1511	=head1 REAL-WORLD EXAMPLE
796		1512
797	Consider the L<Net::FCP> module. It features (among others) the following	1513	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	1514	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	1564	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	1565	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1566	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		1567
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1568	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	1569	result and signals any possible waiters that the request has finished:
854		1570
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1571	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		1572
857	if (end-of-file or data complete) {	1573	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	1574	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	1575	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1576	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	1577	}
862		1578
863	The C<result> method, finally, just waits for the finished signal (if the	1579	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	1580	request was already finished, it doesn't wait, of course, and returns the
865	data:	1581	data:
866		1582
867	$txn->{finished}->wait;	1583	$txn->{finished}->recv;
868	return $txn->{result};	1584	return $txn->{result};
869		1585
870	The actual code goes further and collects all errors (C<die>s, exceptions)	1586	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	1587	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	1588	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	1589	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	1590	problems get reported tot he code that tries to use the result, not in a
875	random callback.	1591	random callback.
876		1592
…		…
907		1623
908	my $quit = AnyEvent->condvar;	1624	my $quit = AnyEvent->condvar;
909		1625
910	$fcp->txn_client_get ($url)->cb (sub {	1626	$fcp->txn_client_get ($url)->cb (sub {
911	...	1627	...
912	$quit->broadcast;	1628	$quit->send;
913	});	1629	});
914		1630
915	$quit->wait;	1631	$quit->recv;
916		1632
917		1633
918	=head1 BENCHMARKS	1634	=head1 BENCHMARKS
919		1635
920	To give you an idea of the performance and overheads that AnyEvent adds	1636	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	1638	of various event loops I prepared some benchmarks.
923		1639
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	1640	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		1641
926	Here is a benchmark of various supported event models used natively and	1642	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	1643	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1644	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	1645	which it is), lets them fire exactly once and destroys them again.
930		1646
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1647	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	1648	distribution.
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	1665	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	1666	and memory usage is not included in the figures.
951		1667
952	I<invoke> is the time, in microseconds, used to invoke a simple	1668	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	1669	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1670	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	1671	signal the end of this phase.
956		1672
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	1673	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	1674	watcher.
959		1675
960	=head3 Results	1676	=head3 Results
961		1677
962	name watchers bytes create invoke destroy comment	1678	name watchers bytes create invoke destroy comment
963	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1679	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
964	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1680	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
965	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1681	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
966	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1682	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
967	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1683	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
968	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1684	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
969	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1685	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
970	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1686	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
971	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1687	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
972	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1688	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
973		1689
974	=head3 Discussion	1690	=head3 Discussion
975		1691
976	The benchmark does I<not> measure scalability of the event loop very	1692	The benchmark does I<not> measure scalability of the event loop very
977	well. For example, a select-based event loop (such as the pure perl one)	1693	well. For example, a select-based event loop (such as the pure perl one)
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	1735	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	1736	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	1737	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	1738	above).
1023		1739
1024	C<POE>, regardless of underlying event loop (whether using its pure	1740	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	1741	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	1742	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	1743	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	1744	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	1745	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1746	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1747	implementation.
		1748
1031	implementation. The design of the POE adaptor class in AnyEvent can not	1749	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	1750	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	1751	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1752	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1753	using multiple sessions is not a good approach, especially regarding
		1754	memory usage, even the author of POE could not come up with a faster
		1755	design).
1035		1756
1036	=head3 Summary	1757	=head3 Summary
1037		1758
1038	=over 4	1759	=over 4
1039		1760
…		…
1050		1771
1051	=back	1772	=back
1052		1773
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	1774	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		1775
1055	This benchmark atcually benchmarks the event loop itself. It works by	1776	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	1777	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	1778	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	1779	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	1780	watcher reads a byte it will write that byte to a random other "server".
1060		1781
1061	The effect is that there will be a lot of I/O watchers, only part of which	1782	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	1783	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	1784	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	1785	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	1786	most timeouts work (and puts extra pressure on the event loops).
1066		1787
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1788	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	1789	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	1790	connections, most of which are idle at any one point in time.
1070		1791
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1792	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	1793	distribution.
…		…
1074	=head3 Explanation of the columns	1795	=head3 Explanation of the columns
1075		1796
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	1797	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	1798	each server has a read and write socket end).
1078		1799
1079	I<create> is the time it takes to create a socketpair (which is	1800	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1801	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		1802
1082	I<request>, the most important value, is the time it takes to handle a	1803	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	1804	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	1805	it to another server. This includes deleting the old timeout and creating
…		…
1086		1807
1087	=head3 Results	1808	=head3 Results
1088		1809
1089	name sockets create request	1810	name sockets create request
1090	EV 20000 69.01 11.16	1811	EV 20000 69.01 11.16
1091	Perl 20000 75.28 112.76	1812	Perl 20000 73.32 35.87
1092	Event 20000 212.62 257.32	1813	Event 20000 212.62 257.32
1093	Glib 20000 651.16 1896.30	1814	Glib 20000 651.16 1896.30
1094	POE 20000 349.67 12317.24 uses POE::Loop::Event	1815	POE 20000 349.67 12317.24 uses POE::Loop::Event
1095		1816
1096	=head3 Discussion	1817	=head3 Discussion
…		…
1118		1839
1119	=head3 Summary	1840	=head3 Summary
1120		1841
1121	=over 4	1842	=over 4
1122		1843
1123	=item * The pure perl implementation performs extremely well, considering	1844	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		1845
1126	=item * Avoid Glib or POE in large projects where performance matters.	1846	=item * Avoid Glib or POE in large projects where performance matters.
1127		1847
1128	=back	1848	=back
1129		1849
…		…
1142		1862
1143	=head3 Results	1863	=head3 Results
1144		1864
1145	name sockets create request	1865	name sockets create request
1146	EV 16 20.00 6.54	1866	EV 16 20.00 6.54
		1867	Perl 16 25.75 12.62
1147	Event 16 81.27 35.86	1868	Event 16 81.27 35.86
1148	Glib 16 32.63 15.48	1869	Glib 16 32.63 15.48
1149	Perl 16 24.62 162.37
1150	POE 16 261.87 276.28 uses POE::Loop::Event	1870	POE 16 261.87 276.28 uses POE::Loop::Event
1151		1871
1152	=head3 Discussion	1872	=head3 Discussion
1153		1873
1154	The benchmark tries to test the performance of a typical small	1874	The benchmark tries to test the performance of a typical small
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	1878	speed most when you have lots of watchers, not when you only have a few of
1159	them).	1879	them).
1160		1880
1161	EV is again fastest.	1881	EV is again fastest.
1162		1882
1163	The C-based event loops Event and Glib come in second this time, as the	1883	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	1884	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	1885	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		1886
1170	POE also performs much better in this case, but is is still far behind the	1887	POE also performs much better in this case, but is is still far behind the
1171	others.	1888	others.
1172		1889
1173	=head3 Summary	1890	=head3 Summary
…		…
1178	watchers, as the management overhead dominates.	1895	watchers, as the management overhead dominates.
1179		1896
1180	=back	1897	=back
1181		1898
1182		1899
		1900	=head1 SIGNALS
		1901
		1902	AnyEvent currently installs handlers for these signals:
		1903
		1904	=over 4
		1905
		1906	=item SIGCHLD
		1907
		1908	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1909	emulation for event loops that do not support them natively. Also, some
		1910	event loops install a similar handler.
		1911
		1912	=item SIGPIPE
		1913
		1914	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1915	when AnyEvent gets loaded.
		1916
		1917	The rationale for this is that AnyEvent users usually do not really depend
		1918	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1919	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1920	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1921	some random socket.
		1922
		1923	The rationale for installing a no-op handler as opposed to ignoring it is
		1924	that this way, the handler will be restored to defaults on exec.
		1925
		1926	Feel free to install your own handler, or reset it to defaults.
		1927
		1928	=back
		1929
		1930	=cut
		1931
		1932	$SIG{PIPE} = sub { }
		1933	unless defined $SIG{PIPE};
		1934
		1935
1183	=head1 FORK	1936	=head1 FORK
1184		1937
1185	Most event libraries are not fork-safe. The ones who are usually are	1938	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	1939	because they rely on inefficient but fork-safe C<select> or C<poll>
		1940	calls. Only L<EV> is fully fork-aware.
1187		1941
1188	If you have to fork, you must either do so I<before> creating your first	1942	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	1943	watcher OR you must not use AnyEvent at all in the child.
1190		1944
1191		1945
…		…
1199	specified in the variable.	1953	specified in the variable.
1200		1954
1201	You can make AnyEvent completely ignore this variable by deleting it	1955	You can make AnyEvent completely ignore this variable by deleting it
1202	before the first watcher gets created, e.g. with a C<BEGIN> block:	1956	before the first watcher gets created, e.g. with a C<BEGIN> block:
1203		1957
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1958	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		1959
1206	use AnyEvent;	1960	use AnyEvent;
		1961
		1962	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1963	be used to probe what backend is used and gain other information (which is
		1964	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1965	$ENV{PERL_ANYEVENT_STRICT}.
		1966
		1967
		1968	=head1 BUGS
		1969
		1970	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1971	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1972	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1973	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1974	pronounced).
1207		1975
1208		1976
1209	=head1 SEE ALSO	1977	=head1 SEE ALSO
1210		1978
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1979	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1980
		1981	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	1982	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		1983
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1984	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1985	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1986	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1987	L<AnyEvent::Impl::POE>.
1219		1988
		1989	Non-blocking file handles, sockets, TCP clients and
		1990	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1991
		1992	Asynchronous DNS: L<AnyEvent::DNS>.
		1993
		1994	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1995
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1996	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1221		1997
1222		1998
1223	=head1 AUTHOR	1999	=head1 AUTHOR
1224		2000
1225	Marc Lehmann <schmorp@schmorp.de>	2001	Marc Lehmann <schmorp@schmorp.de>
1226	http://home.schmorp.de/	2002	http://home.schmorp.de/
1227		2003
1228	=cut	2004	=cut
1229		2005
1230	1	2006	1
1231		2007

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