ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.103 by root, Tue Apr 29 07:15:49 2008 UTC vs.
Revision 1.238 by root, Thu Jul 16 03:48:33 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, 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		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
…		…
78	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>
79	module.	109	module.
80		110
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	113	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
102	starts using it, all bets are off. Maybe you should tell their authors to	132	starts using it, all bets are off. Maybe you should tell their authors to
103	use AnyEvent so their modules work together with others seamlessly...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
112	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
113	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
114		144
115	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
117	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
121	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
137	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
186	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
215	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
235	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
242	Multiple signal occurances can be clumped together into one callback	360	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
246		364
247	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	366	between multiple watchers.
249		367
250	This watcher might use C<%SIG>, so programs overwriting those signals	368	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
260		378
261	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
262	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
263	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
272	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
275		403
276	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
279		408
280	Example: fork a process and wait for it	409	Example: fork a process and wait for it
281		410
282	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
283		412
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
287		414
288	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
289	pid => $pid,	416	pid => $pid,
290	cb => sub {	417	cb => sub {
291	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
293	$done->broadcast;	420	$done->send;
294	},	421	},
295	);	422	);
296		423
297	# do something else, then wait for process exit	424	# do something else, then wait for process exit
298	$done->wait;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
299		461
300	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
301		463
		464	If you are familiar with some event loops you will know that all of them
		465	require you to run some blocking "loop", "run" or similar function that
		466	will actively watch for new events and call your callbacks.
		467
		468	AnyEvent is different, it expects somebody else to run the event loop and
		469	will only block when necessary (usually when told by the user).
		470
		471	The instrument to do that is called a "condition variable", so called
		472	because they represent a condition that must become true.
		473
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	474	Condition variables can be created by calling the C<< AnyEvent->condvar
303	method without any arguments.	475	>> method, usually without arguments. The only argument pair allowed is
304		476
305	A condition variable waits for a condition - precisely that the C<<	477	C<cb>, which specifies a callback to be called when the condition variable
306	->broadcast >> method has been called.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
307		480
308	They are very useful to signal that a condition has been fulfilled, for	481	After creation, the condition variable is "false" until it becomes "true"
		482	by calling the C<send> method (or calling the condition variable as if it
		483	were a callback, read about the caveats in the description for the C<<
		484	->send >> method).
		485
		486	Condition variables are similar to callbacks, except that you can
		487	optionally wait for them. They can also be called merge points - points
		488	in time where multiple outstanding events have been processed. And yet
		489	another way to call them is transactions - each condition variable can be
		490	used to represent a transaction, which finishes at some point and delivers
		491	a result.
		492
		493	Condition variables are very useful to signal that something has finished,
309	example, if you write a module that does asynchronous http requests,	494	for example, if you write a module that does asynchronous http requests,
310	then a condition variable would be the ideal candidate to signal the	495	then a condition variable would be the ideal candidate to signal the
311	availability of results.	496	availability of results. The user can either act when the callback is
		497	called or can synchronously C<< ->recv >> for the results.
312		498
313	You can also use condition variables to block your main program until	499	You can also use them to simulate traditional event loops - for example,
314	an event occurs - for example, you could C<< ->wait >> in your main	500	you can block your main program until an event occurs - for example, you
315	program until the user clicks the Quit button in your app, which would C<<	501	could C<< ->recv >> in your main program until the user clicks the Quit
316	->broadcast >> the "quit" event.	502	button of your app, which would C<< ->send >> the "quit" event.
317		503
318	Note that condition variables recurse into the event loop - if you have	504	Note that condition variables recurse into the event loop - if you have
319	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	505	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
320	lose. Therefore, condition variables are good to export to your caller, but	506	lose. Therefore, condition variables are good to export to your caller, but
321	you should avoid making a blocking wait yourself, at least in callbacks,	507	you should avoid making a blocking wait yourself, at least in callbacks,
322	as this asks for trouble.	508	as this asks for trouble.
323		509
324	This object has two methods:	510	Condition variables are represented by hash refs in perl, and the keys
		511	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		512	easy (it is often useful to build your own transaction class on top of
		513	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		514	it's C<new> method in your own C<new> method.
		515
		516	There are two "sides" to a condition variable - the "producer side" which
		517	eventually calls C<< -> send >>, and the "consumer side", which waits
		518	for the send to occur.
		519
		520	Example: wait for a timer.
		521
		522	# wait till the result is ready
		523	my $result_ready = AnyEvent->condvar;
		524
		525	# do something such as adding a timer
		526	# or socket watcher the calls $result_ready->send
		527	# when the "result" is ready.
		528	# in this case, we simply use a timer:
		529	my $w = AnyEvent->timer (
		530	after => 1,
		531	cb => sub { $result_ready->send },
		532	);
		533
		534	# this "blocks" (while handling events) till the callback
		535	# calls send
		536	$result_ready->recv;
		537
		538	Example: wait for a timer, but take advantage of the fact that
		539	condition variables are also code references.
		540
		541	my $done = AnyEvent->condvar;
		542	my $delay = AnyEvent->timer (after => 5, cb => $done);
		543	$done->recv;
		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
		562	=head3 METHODS FOR PRODUCERS
		563
		564	These methods should only be used by the producing side, i.e. the
		565	code/module that eventually sends the signal. Note that it is also
		566	the producer side which creates the condvar in most cases, but it isn't
		567	uncommon for the consumer to create it as well.
325		568
326	=over 4	569	=over 4
327		570
		571	=item $cv->send (...)
		572
		573	Flag the condition as ready - a running C<< ->recv >> and all further
		574	calls to C<recv> will (eventually) return after this method has been
		575	called. If nobody is waiting the send will be remembered.
		576
		577	If a callback has been set on the condition variable, it is called
		578	immediately from within send.
		579
		580	Any arguments passed to the C<send> call will be returned by all
		581	future C<< ->recv >> calls.
		582
		583	Condition variables are overloaded so one can call them directly
		584	(as a code reference). Calling them directly is the same as calling
		585	C<send>. Note, however, that many C-based event loops do not handle
		586	overloading, so as tempting as it may be, passing a condition variable
		587	instead of a callback does not work. Both the pure perl and EV loops
		588	support overloading, however, as well as all functions that use perl to
		589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		590	example).
		591
		592	=item $cv->croak ($error)
		593
		594	Similar to send, but causes all call's to C<< ->recv >> to invoke
		595	C<Carp::croak> with the given error message/object/scalar.
		596
		597	This can be used to signal any errors to the condition variable
		598	user/consumer.
		599
		600	=item $cv->begin ([group callback])
		601
328	=item $cv->wait	602	=item $cv->end
329		603
330	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	604	These two methods can be used to combine many transactions/events into
		605	one. For example, a function that pings many hosts in parallel might want
		606	to use a condition variable for the whole process.
		607
		608	Every call to C<< ->begin >> will increment a counter, and every call to
		609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		610	>>, the (last) callback passed to C<begin> will be executed. That callback
		611	is I<supposed> to call C<< ->send >>, but that is not required. If no
		612	callback was set, C<send> will be called without any arguments.
		613
		614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
		645
		646	my $cv = AnyEvent->condvar;
		647
		648	my %result;
		649	$cv->begin (sub { $cv->send (\%result) });
		650
		651	for my $host (@list_of_hosts) {
		652	$cv->begin;
		653	ping_host_then_call_callback $host, sub {
		654	$result{$host} = ...;
		655	$cv->end;
		656	};
		657	}
		658
		659	$cv->end;
		660
		661	This code fragment supposedly pings a number of hosts and calls
		662	C<send> after results for all then have have been gathered - in any
		663	order. To achieve this, the code issues a call to C<begin> when it starts
		664	each ping request and calls C<end> when it has received some result for
		665	it. Since C<begin> and C<end> only maintain a counter, the order in which
		666	results arrive is not relevant.
		667
		668	There is an additional bracketing call to C<begin> and C<end> outside the
		669	loop, which serves two important purposes: first, it sets the callback
		670	to be called once the counter reaches C<0>, and second, it ensures that
		671	C<send> is called even when C<no> hosts are being pinged (the loop
		672	doesn't execute once).
		673
		674	This is the general pattern when you "fan out" into multiple (but
		675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
		676	the callback and ensure C<end> is called at least once, and then, for each
		677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
		679
		680	=back
		681
		682	=head3 METHODS FOR CONSUMERS
		683
		684	These methods should only be used by the consuming side, i.e. the
		685	code awaits the condition.
		686
		687	=over 4
		688
		689	=item $cv->recv
		690
		691	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	692	>> methods have been called on c<$cv>, while servicing other watchers
		693	normally.
332		694
333	You can only wait once on a condition - additional calls will return	695	You can only wait once on a condition - additional calls are valid but
334	immediately.	696	will return immediately.
		697
		698	If an error condition has been set by calling C<< ->croak >>, then this
		699	function will call C<croak>.
		700
		701	In list context, all parameters passed to C<send> will be returned,
		702	in scalar context only the first one will be returned.
335		703
336	Not all event models support a blocking wait - some die in that case	704	Not all event models support a blocking wait - some die in that case
337	(programs might want to do that to stay interactive), so I<if you are	705	(programs might want to do that to stay interactive), so I<if you are
338	using this from a module, never require a blocking wait>, but let the	706	using this from a module, never require a blocking wait>, but let the
339	caller decide whether the call will block or not (for example, by coupling	707	caller decide whether the call will block or not (for example, by coupling
340	condition variables with some kind of request results and supporting	708	condition variables with some kind of request results and supporting
341	callbacks so the caller knows that getting the result will not block,	709	callbacks so the caller knows that getting the result will not block,
342	while still suppporting blocking waits if the caller so desires).	710	while still supporting blocking waits if the caller so desires).
343		711
344	Another reason I<never> to C<< ->wait >> in a module is that you cannot	712	Another reason I<never> to C<< ->recv >> in a module is that you cannot
345	sensibly have two C<< ->wait >>'s in parallel, as that would require	713	sensibly have two C<< ->recv >>'s in parallel, as that would require
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	714	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	715	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		716
351	=item $cv->broadcast	717	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		718	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		719	versions and also integrates coroutines into AnyEvent, making blocking
		720	C<< ->recv >> calls perfectly safe as long as they are done from another
		721	coroutine (one that doesn't run the event loop).
352		722
353	Flag the condition as ready - a running C<< ->wait >> and all further	723	You can ensure that C<< -recv >> never blocks by setting a callback and
354	calls to C<wait> will (eventually) return after this method has been	724	only calling C<< ->recv >> from within that callback (or at a later
355	called. If nobody is waiting the broadcast will be remembered..	725	time). This will work even when the event loop does not support blocking
		726	waits otherwise.
		727
		728	=item $bool = $cv->ready
		729
		730	Returns true when the condition is "true", i.e. whether C<send> or
		731	C<croak> have been called.
		732
		733	=item $cb = $cv->cb ($cb->($cv))
		734
		735	This is a mutator function that returns the callback set and optionally
		736	replaces it before doing so.
		737
		738	The callback will be called when the condition becomes "true", i.e. when
		739	C<send> or C<croak> are called, with the only argument being the condition
		740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
356		742
357	=back	743	=back
358		744
359	Example:	745	=head1 SUPPORTED EVENT LOOPS/BACKENDS
360		746
361	# wait till the result is ready	747	The available backend classes are (every class has its own manpage):
362	my $result_ready = AnyEvent->condvar;
363		748
364	# do something such as adding a timer	749	=over 4
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372		750
373	# this "blocks" (while handling events) till the watcher	751	=item Backends that are autoprobed when no other event loop can be found.
374	# calls broadcast	752
375	$result_ready->wait;	753	EV is the preferred backend when no other event loop seems to be in
		754	use. If EV is not installed, then AnyEvent will try Event, and, failing
		755	that, will fall back to its own pure-perl implementation, which is
		756	available everywhere as it comes with AnyEvent itself.
		757
		758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		761
		762	=item Backends that are transparently being picked up when they are used.
		763
		764	These will be used when they are currently loaded when the first watcher
		765	is created, in which case it is assumed that the application is using
		766	them. This means that AnyEvent will automatically pick the right backend
		767	when the main program loads an event module before anything starts to
		768	create watchers. Nothing special needs to be done by the main program.
		769
		770	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		771	AnyEvent::Impl::Tk based on Tk, very broken.
		772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		773	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		774
		775	=item Backends with special needs.
		776
		777	Qt requires the Qt::Application to be instantiated first, but will
		778	otherwise be picked up automatically. As long as the main program
		779	instantiates the application before any AnyEvent watchers are created,
		780	everything should just work.
		781
		782	AnyEvent::Impl::Qt based on Qt.
		783
		784	Support for IO::Async can only be partial, as it is too broken and
		785	architecturally limited to even support the AnyEvent API. It also
		786	is the only event loop that needs the loop to be set explicitly, so
		787	it can only be used by a main program knowing about AnyEvent. See
		788	L<AnyEvent::Impl::Async> for the gory details.
		789
		790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		791
		792	=item Event loops that are indirectly supported via other backends.
		793
		794	Some event loops can be supported via other modules:
		795
		796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		797
		798	B<WxWidgets> has no support for watching file handles. However, you can
		799	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		800	polls 20 times per second, which was considered to be too horrible to even
		801	consider for AnyEvent.
		802
		803	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		804	backend, so it can be supported through POE.
		805
		806	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		807	load L<POE> when detecting them, in the hope that POE will pick them up,
		808	in which case everything will be automatic.
		809
		810	=back
376		811
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	812	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		813
		814	These are not normally required to use AnyEvent, but can be useful to
		815	write AnyEvent extension modules.
		816
379	=over 4	817	=over 4
380		818
381	=item $AnyEvent::MODEL	819	=item $AnyEvent::MODEL
382		820
383	Contains C<undef> until the first watcher is being created. Then it	821	Contains C<undef> until the first watcher is being created, before the
		822	backend has been autodetected.
		823
384	contains the event model that is being used, which is the name of the	824	Afterwards it contains the event model that is being used, which is the
385	Perl class implementing the model. This class is usually one of the	825	name of the Perl class implementing the model. This class is usually one
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	826	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	827	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
388		828	will be C<urxvt::anyevent>).
389	The known classes so far are:
390
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401
402	There is no support for WxWidgets, as WxWidgets has no support for
403	watching file handles. However, you can use WxWidgets through the
404	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
405	second, which was considered to be too horrible to even consider for
406	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
407	it's adaptor.
408
409	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
410	autodetecting them.
411		829
412	=item AnyEvent::detect	830	=item AnyEvent::detect
413		831
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	832	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	if necessary. You should only call this function right before you would	833	if necessary. You should only call this function right before you would
416	have created an AnyEvent watcher anyway, that is, as late as possible at	834	have created an AnyEvent watcher anyway, that is, as late as possible at
417	runtime.	835	runtime, and not e.g. while initialising of your module.
		836
		837	If you need to do some initialisation before AnyEvent watchers are
		838	created, use C<post_detect>.
		839
		840	=item $guard = AnyEvent::post_detect { BLOCK }
		841
		842	Arranges for the code block to be executed as soon as the event model is
		843	autodetected (or immediately if this has already happened).
		844
		845	The block will be executed I<after> the actual backend has been detected
		846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		848	other initialisations - see the sources of L<AnyEvent::Strict> or
		849	L<AnyEvent::AIO> to see how this is used.
		850
		851	The most common usage is to create some global watchers, without forcing
		852	event module detection too early, for example, L<AnyEvent::AIO> creates
		853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		854	avoid autodetecting the event module at load time.
		855
		856	If called in scalar or list context, then it creates and returns an object
		857	that automatically removes the callback again when it is destroyed. See
		858	L<Coro::BDB> for a case where this is useful.
		859
		860	=item @AnyEvent::post_detect
		861
		862	If there are any code references in this array (you can C<push> to it
		863	before or after loading AnyEvent), then they will called directly after
		864	the event loop has been chosen.
		865
		866	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		867	if it is defined then the event loop has already been detected, and the
		868	array will be ignored.
		869
		870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		871	it,as it takes care of these details.
		872
		873	This variable is mainly useful for modules that can do something useful
		874	when AnyEvent is used and thus want to know when it is initialised, but do
		875	not need to even load it by default. This array provides the means to hook
		876	into AnyEvent passively, without loading it.
418		877
419	=back	878	=back
420		879
421	=head1 WHAT TO DO IN A MODULE	880	=head1 WHAT TO DO IN A MODULE
422		881
…		…
426	Be careful when you create watchers in the module body - AnyEvent will	885	Be careful when you create watchers in the module body - AnyEvent will
427	decide which event module to use as soon as the first method is called, so	886	decide which event module to use as soon as the first method is called, so
428	by calling AnyEvent in your module body you force the user of your module	887	by calling AnyEvent in your module body you force the user of your module
429	to load the event module first.	888	to load the event module first.
430		889
431	Never call C<< ->wait >> on a condition variable unless you I<know> that	890	Never call C<< ->recv >> on a condition variable unless you I<know> that
432	the C<< ->broadcast >> method has been called on it already. This is	891	the C<< ->send >> method has been called on it already. This is
433	because it will stall the whole program, and the whole point of using	892	because it will stall the whole program, and the whole point of using
434	events is to stay interactive.	893	events is to stay interactive.
435		894
436	It is fine, however, to call C<< ->wait >> when the user of your module	895	It is fine, however, to call C<< ->recv >> when the user of your module
437	requests it (i.e. if you create a http request object ad have a method	896	requests it (i.e. if you create a http request object ad have a method
438	called C<results> that returns the results, it should call C<< ->wait >>	897	called C<results> that returns the results, it should call C<< ->recv >>
439	freely, as the user of your module knows what she is doing. always).	898	freely, as the user of your module knows what she is doing. always).
440		899
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	900	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		901
443	There will always be a single main program - the only place that should	902	There will always be a single main program - the only place that should
…		…
445		904
446	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	905	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
447	do anything special (it does not need to be event-based) and let AnyEvent	906	do anything special (it does not need to be event-based) and let AnyEvent
448	decide which implementation to chose if some module relies on it.	907	decide which implementation to chose if some module relies on it.
449		908
450	If the main program relies on a specific event model. For example, in	909	If the main program relies on a specific event model - for example, in
451	Gtk2 programs you have to rely on the Glib module. You should load the	910	Gtk2 programs you have to rely on the Glib module - you should load the
452	event module before loading AnyEvent or any module that uses it: generally	911	event module before loading AnyEvent or any module that uses it: generally
453	speaking, you should load it as early as possible. The reason is that	912	speaking, you should load it as early as possible. The reason is that
454	modules might create watchers when they are loaded, and AnyEvent will	913	modules might create watchers when they are loaded, and AnyEvent will
455	decide on the event model to use as soon as it creates watchers, and it	914	decide on the event model to use as soon as it creates watchers, and it
456	might chose the wrong one unless you load the correct one yourself.	915	might chose the wrong one unless you load the correct one yourself.
457		916
458	You can chose to use a rather inefficient pure-perl implementation by	917	You can chose to use a pure-perl implementation by loading the
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	918	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	behaviour everywhere, but letting AnyEvent chose is generally better.	919	everywhere, but letting AnyEvent chose the model is generally better.
		920
		921	=head2 MAINLOOP EMULATION
		922
		923	Sometimes (often for short test scripts, or even standalone programs who
		924	only want to use AnyEvent), you do not want to run a specific event loop.
		925
		926	In that case, you can use a condition variable like this:
		927
		928	AnyEvent->condvar->recv;
		929
		930	This has the effect of entering the event loop and looping forever.
		931
		932	Note that usually your program has some exit condition, in which case
		933	it is better to use the "traditional" approach of storing a condition
		934	variable somewhere, waiting for it, and sending it when the program should
		935	exit cleanly.
		936
461		937
462	=head1 OTHER MODULES	938	=head1 OTHER MODULES
463		939
464	The following is a non-exhaustive list of additional modules that use	940	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	941	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
466	in the same program. Some of the modules come with AnyEvent, some are	942	modules and other event loops in the same program. Some of the modules
467	available via CPAN.	943	come with AnyEvent, most are available via CPAN.
468		944
469	=over 4	945	=over 4
470		946
471	=item L<AnyEvent::Util>	947	=item L<AnyEvent::Util>
472		948
473	Contains various utility functions that replace often-used but blocking	949	Contains various utility functions that replace often-used but blocking
474	functions such as C<inet_aton> by event-/callback-based versions.	950	functions such as C<inet_aton> by event-/callback-based versions.
475		951
		952	=item L<AnyEvent::Socket>
		953
		954	Provides various utility functions for (internet protocol) sockets,
		955	addresses and name resolution. Also functions to create non-blocking tcp
		956	connections or tcp servers, with IPv6 and SRV record support and more.
		957
476	=item L<AnyEvent::Handle>	958	=item L<AnyEvent::Handle>
477		959
478	Provide read and write buffers and manages watchers for reads and writes.	960	Provide read and write buffers, manages watchers for reads and writes,
		961	supports raw and formatted I/O, I/O queued and fully transparent and
		962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
479		963
480	=item L<AnyEvent::Socket>	964	=item L<AnyEvent::DNS>
481		965
482	Provides a means to do non-blocking connects, accepts etc.	966	Provides rich asynchronous DNS resolver capabilities.
		967
		968	=item L<AnyEvent::HTTP>
		969
		970	A simple-to-use HTTP library that is capable of making a lot of concurrent
		971	HTTP requests.
483		972
484	=item L<AnyEvent::HTTPD>	973	=item L<AnyEvent::HTTPD>
485		974
486	Provides a simple web application server framework.	975	Provides a simple web application server framework.
487		976
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492
493	=item L<AnyEvent::FastPing>	977	=item L<AnyEvent::FastPing>
494		978
495	The fastest ping in the west.	979	The fastest ping in the west.
496		980
		981	=item L<AnyEvent::DBI>
		982
		983	Executes L<DBI> requests asynchronously in a proxy process.
		984
		985	=item L<AnyEvent::AIO>
		986
		987	Truly asynchronous I/O, should be in the toolbox of every event
		988	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		989	together.
		990
		991	=item L<AnyEvent::BDB>
		992
		993	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		994	L<BDB> and AnyEvent together.
		995
		996	=item L<AnyEvent::GPSD>
		997
		998	A non-blocking interface to gpsd, a daemon delivering GPS information.
		999
497	=item L<Net::IRC3>	1000	=item L<AnyEvent::IRC>
498		1001
499	AnyEvent based IRC client module family.	1002	AnyEvent based IRC client module family (replacing the older Net::IRC3).
500		1003
501	=item L<Net::XMPP2>	1004	=item L<AnyEvent::XMPP>
502		1005
503	AnyEvent based XMPP (Jabber protocol) module family.	1006	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1007	Net::XMPP2>.
		1008
		1009	=item L<AnyEvent::IGS>
		1010
		1011	A non-blocking interface to the Internet Go Server protocol (used by
		1012	L<App::IGS>).
504		1013
505	=item L<Net::FCP>	1014	=item L<Net::FCP>
506		1015
507	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1016	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
508	of AnyEvent.	1017	of AnyEvent.
…		…
511		1020
512	High level API for event-based execution flow control.	1021	High level API for event-based execution flow control.
513		1022
514	=item L<Coro>	1023	=item L<Coro>
515		1024
516	Has special support for AnyEvent.	1025	Has special support for AnyEvent via L<Coro::AnyEvent>.
517
518	=item L<IO::Lambda>
519
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531		1026
532	=back	1027	=back
533		1028
534	=cut	1029	=cut
535		1030
536	package AnyEvent;	1031	package AnyEvent;
537		1032
538	no warnings;	1033	no warnings;
539	use strict;	1034	use strict qw(vars subs);
540		1035
541	use Carp;	1036	use Carp;
542		1037
543	our $VERSION = '3.3';	1038	our $VERSION = 4.82;
544	our $MODEL;	1039	our $MODEL;
545		1040
546	our $AUTOLOAD;	1041	our $AUTOLOAD;
547	our @ISA;	1042	our @ISA;
548		1043
		1044	our @REGISTRY;
		1045
		1046	our $WIN32;
		1047
		1048	BEGIN {
		1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1051
		1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1053	if ${^TAINT};
		1054	}
		1055
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		1057
551	our @REGISTRY;	1058	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1059
		1060	{
		1061	my $idx;
		1062	$PROTOCOL{$_} = ++$idx
		1063	for reverse split /\s*,\s*/,
		1064	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		1065	}
552		1066
553	my @models = (	1067	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	1068	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	1069	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],	1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1071	# everything below here will not be autoprobed
		1072	# as the pureperl backend should work everywhere
		1073	# and is usually faster
		1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
559	[Tk:: => AnyEvent::Impl::Tk::],	1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1077	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1078	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
560	[Wx:: => AnyEvent::Impl::POE::],	1079	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],	1080	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1081	# IO::Async is just too broken - we would need workarounds for its
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1082	# byzantine signal and broken child handling, among others.
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1083	# IO::Async is rather hard to detect, as it doesn't have any
		1084	# obvious default class.
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1085	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1086	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1087	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
567	);	1088	);
568		1089
569	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	1090	our %method = map +($_ => 1),
		1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1092
		1093	our @post_detect;
		1094
		1095	sub post_detect(&) {
		1096	my ($cb) = @_;
		1097
		1098	if ($MODEL) {
		1099	$cb->();
		1100
		1101	1
		1102	} else {
		1103	push @post_detect, $cb;
		1104
		1105	defined wantarray
		1106	? bless \$cb, "AnyEvent::Util::postdetect"
		1107	: ()
		1108	}
		1109	}
		1110
		1111	sub AnyEvent::Util::postdetect::DESTROY {
		1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1113	}
570		1114
571	sub detect() {	1115	sub detect() {
572	unless ($MODEL) {	1116	unless ($MODEL) {
573	no strict 'refs';	1117	no strict 'refs';
		1118	local $SIG{__DIE__};
574		1119
575	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1120	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576	my $model = "AnyEvent::Impl::$1";	1121	my $model = "AnyEvent::Impl::$1";
577	if (eval "require $model") {	1122	if (eval "require $model") {
578	$MODEL = $model;	1123	$MODEL = $model;
579	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1124	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1;
580	} else {	1125	} else {
581	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1126	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose;
582	}	1127	}
583	}	1128	}
584		1129
585	# check for already loaded models	1130	# check for already loaded models
586	unless ($MODEL) {	1131	unless ($MODEL) {
…		…
608	last;	1153	last;
609	}	1154	}
610	}	1155	}
611		1156
612	$MODEL	1157	$MODEL
613	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
614	}	1159	}
615	}	1160	}
616		1161
		1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1163
617	unshift @ISA, $MODEL;	1164	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1165
		1166	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1167
		1168	(shift @post_detect)->() while @post_detect;
619	}	1169	}
620		1170
621	$MODEL	1171	$MODEL
622	}	1172	}
623		1173
…		…
631		1181
632	my $class = shift;	1182	my $class = shift;
633	$class->$func (@_);	1183	$class->$func (@_);
634	}	1184	}
635		1185
		1186	# utility function to dup a filehandle. this is used by many backends
		1187	# to support binding more than one watcher per filehandle (they usually
		1188	# allow only one watcher per fd, so we dup it to get a different one).
		1189	sub _dupfh($$;$$) {
		1190	my ($poll, $fh, $r, $w) = @_;
		1191
		1192	# cygwin requires the fh mode to be matching, unix doesn't
		1193	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
		1194
		1195	open my $fh2, "$mode&", $fh
		1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1197
		1198	# we assume CLOEXEC is already set by perl in all important cases
		1199
		1200	($fh2, $rw)
		1201	}
		1202
636	package AnyEvent::Base;	1203	package AnyEvent::Base;
637		1204
		1205	# default implementations for many methods
		1206
		1207	BEGIN {
		1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1209	*_time = \&Time::HiRes::time;
		1210	# if (eval "use POSIX (); (POSIX::times())...
		1211	} else {
		1212	*_time = sub { time }; # epic fail
		1213	}
		1214	}
		1215
		1216	sub time { _time }
		1217	sub now { _time }
		1218	sub now_update { }
		1219
638	# default implementation for ->condvar, ->wait, ->broadcast	1220	# default implementation for ->condvar
639		1221
640	sub condvar {	1222	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	1224	}
651		1225
652	# default implementation for ->signal	1226	# default implementation for ->signal
653		1227
654	our %SIG_CB;	1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1229
		1230	sub _signal_exec {
		1231	sysread $SIGPIPE_R, my $dummy, 4;
		1232
		1233	while (%SIG_EV) {
		1234	for (keys %SIG_EV) {
		1235	delete $SIG_EV{$_};
		1236	$_->() for values %{ $SIG_CB{$_} || {} };
		1237	}
		1238	}
		1239	}
655		1240
656	sub signal {	1241	sub signal {
657	my (undef, %arg) = @_;	1242	my (undef, %arg) = @_;
658		1243
		1244	unless ($SIGPIPE_R) {
		1245	require Fcntl;
		1246
		1247	if (AnyEvent::WIN32) {
		1248	require AnyEvent::Util;
		1249
		1250	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1251	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1252	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1253	} else {
		1254	pipe $SIGPIPE_R, $SIGPIPE_W;
		1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1257
		1258	# not strictly required, as $^F is normally 2, but let's make sure...
		1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1261	}
		1262
		1263	$SIGPIPE_R
		1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1265
		1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1267	}
		1268
659	my $signal = uc $arg{signal}	1269	my $signal = uc $arg{signal}
660	or Carp::croak "required option 'signal' is missing";	1270	or Carp::croak "required option 'signal' is missing";
661		1271
662	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
663	$SIG{$signal} ||= sub {	1273	$SIG{$signal} ||= sub {
664	$_->() for values %{ $SIG_CB{$signal} || {} };	1274	local $!;
		1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1276	undef $SIG_EV{$signal};
665	};	1277	};
666		1278
667	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
668	}	1280	}
669		1281
670	sub AnyEvent::Base::Signal::DESTROY {	1282	sub AnyEvent::Base::signal::DESTROY {
671	my ($signal, $cb) = @{$_[0]};	1283	my ($signal, $cb) = @{$_[0]};
672		1284
673	delete $SIG_CB{$signal}{$cb};	1285	delete $SIG_CB{$signal}{$cb};
674		1286
		1287	# delete doesn't work with older perls - they then
		1288	# print weird messages, or just unconditionally exit
		1289	# instead of getting the default action.
675	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1290	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
676	}	1291	}
677		1292
678	# default implementation for ->child	1293	# default implementation for ->child
679		1294
680	our %PID_CB;	1295	our %PID_CB;
681	our $CHLD_W;	1296	our $CHLD_W;
682	our $CHLD_DELAY_W;	1297	our $CHLD_DELAY_W;
683	our $PID_IDLE;
684	our $WNOHANG;	1298	our $WNOHANG;
685		1299
686	sub _child_wait {	1300	sub _sigchld {
687	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
688	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
689	(values %{ $PID_CB{0} || {} });	1303	(values %{ $PID_CB{0} || {} });
690	}	1304	}
691
692	undef $PID_IDLE;
693	}
694
695	sub _sigchld {
696	# make sure we deliver these changes "synchronous" with the event loop.
697	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
698	undef $CHLD_DELAY_W;
699	&_child_wait;
700	});
701	}	1305	}
702		1306
703	sub child {	1307	sub child {
704	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
705		1309
706	defined (my $pid = $arg{pid} + 0)	1310	defined (my $pid = $arg{pid} + 0)
707	or Carp::croak "required option 'pid' is missing";	1311	or Carp::croak "required option 'pid' is missing";
708		1312
709	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
710		1314
711	unless ($WNOHANG) {
712	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1315	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
713	}
714		1316
715	unless ($CHLD_W) {	1317	unless ($CHLD_W) {
716	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717	# child could be a zombie already, so make at least one round	1319	# child could be a zombie already, so make at least one round
718	&_sigchld;	1320	&_sigchld;
719	}	1321	}
720		1322
721	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
722	}	1324	}
723		1325
724	sub AnyEvent::Base::Child::DESTROY {	1326	sub AnyEvent::Base::child::DESTROY {
725	my ($pid, $cb) = @{$_[0]};	1327	my ($pid, $cb) = @{$_[0]};
726		1328
727	delete $PID_CB{$pid}{$cb};	1329	delete $PID_CB{$pid}{$cb};
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		1331
730	undef $CHLD_W unless keys %PID_CB;	1332	undef $CHLD_W unless keys %PID_CB;
731	}	1333	}
		1334
		1335	# idle emulation is done by simply using a timer, regardless
		1336	# of whether the process is idle or not, and not letting
		1337	# the callback use more than 50% of the time.
		1338	sub idle {
		1339	my (undef, %arg) = @_;
		1340
		1341	my ($cb, $w, $rcb) = $arg{cb};
		1342
		1343	$rcb = sub {
		1344	if ($cb) {
		1345	$w = _time;
		1346	&$cb;
		1347	$w = _time - $w;
		1348
		1349	# never use more then 50% of the time for the idle watcher,
		1350	# within some limits
		1351	$w = 0.0001 if $w < 0.0001;
		1352	$w = 5 if $w > 5;
		1353
		1354	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1355	} else {
		1356	# clean up...
		1357	undef $w;
		1358	undef $rcb;
		1359	}
		1360	};
		1361
		1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1363
		1364	bless \\$cb, "AnyEvent::Base::idle"
		1365	}
		1366
		1367	sub AnyEvent::Base::idle::DESTROY {
		1368	undef $${$_[0]};
		1369	}
		1370
		1371	package AnyEvent::CondVar;
		1372
		1373	our @ISA = AnyEvent::CondVar::Base::;
		1374
		1375	package AnyEvent::CondVar::Base;
		1376
		1377	use overload
		1378	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1379	fallback => 1;
		1380
		1381	sub _send {
		1382	# nop
		1383	}
		1384
		1385	sub send {
		1386	my $cv = shift;
		1387	$cv->{_ae_sent} = [@_];
		1388	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1389	$cv->_send;
		1390	}
		1391
		1392	sub croak {
		1393	$_[0]{_ae_croak} = $_[1];
		1394	$_[0]->send;
		1395	}
		1396
		1397	sub ready {
		1398	$_[0]{_ae_sent}
		1399	}
		1400
		1401	sub _wait {
		1402	AnyEvent->one_event while !$_[0]{_ae_sent};
		1403	}
		1404
		1405	sub recv {
		1406	$_[0]->_wait;
		1407
		1408	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1409	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1410	}
		1411
		1412	sub cb {
		1413	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1414	$_[0]{_ae_cb}
		1415	}
		1416
		1417	sub begin {
		1418	++$_[0]{_ae_counter};
		1419	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1420	}
		1421
		1422	sub end {
		1423	return if --$_[0]{_ae_counter};
		1424	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1425	}
		1426
		1427	# undocumented/compatibility with pre-3.4
		1428	*broadcast = \&send;
		1429	*wait = \&_wait;
		1430
		1431	=head1 ERROR AND EXCEPTION HANDLING
		1432
		1433	In general, AnyEvent does not do any error handling - it relies on the
		1434	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1435	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1436	checking of all AnyEvent methods, however, which is highly useful during
		1437	development.
		1438
		1439	As for exception handling (i.e. runtime errors and exceptions thrown while
		1440	executing a callback), this is not only highly event-loop specific, but
		1441	also not in any way wrapped by this module, as this is the job of the main
		1442	program.
		1443
		1444	The pure perl event loop simply re-throws the exception (usually
		1445	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1446	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1447	so on.
		1448
		1449	=head1 ENVIRONMENT VARIABLES
		1450
		1451	The following environment variables are used by this module or its
		1452	submodules.
		1453
		1454	Note that AnyEvent will remove I<all> environment variables starting with
		1455	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1456	enabled.
		1457
		1458	=over 4
		1459
		1460	=item C<PERL_ANYEVENT_VERBOSE>
		1461
		1462	By default, AnyEvent will be completely silent except in fatal
		1463	conditions. You can set this environment variable to make AnyEvent more
		1464	talkative.
		1465
		1466	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1467	conditions, such as not being able to load the event model specified by
		1468	C<PERL_ANYEVENT_MODEL>.
		1469
		1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1471	model it chooses.
		1472
		1473	=item C<PERL_ANYEVENT_STRICT>
		1474
		1475	AnyEvent does not do much argument checking by default, as thorough
		1476	argument checking is very costly. Setting this variable to a true value
		1477	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1478	check the arguments passed to most method calls. If it finds any problems,
		1479	it will croak.
		1480
		1481	In other words, enables "strict" mode.
		1482
		1483	Unlike C<use strict>, it is definitely recommended to keep it off in
		1484	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1485	developing programs can be very useful, however.
		1486
		1487	=item C<PERL_ANYEVENT_MODEL>
		1488
		1489	This can be used to specify the event model to be used by AnyEvent, before
		1490	auto detection and -probing kicks in. It must be a string consisting
		1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1492	and the resulting module name is loaded and if the load was successful,
		1493	used as event model. If it fails to load AnyEvent will proceed with
		1494	auto detection and -probing.
		1495
		1496	This functionality might change in future versions.
		1497
		1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1499	could start your program like this:
		1500
		1501	PERL_ANYEVENT_MODEL=Perl perl ...
		1502
		1503	=item C<PERL_ANYEVENT_PROTOCOLS>
		1504
		1505	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1506	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1507	of auto probing).
		1508
		1509	Must be set to a comma-separated list of protocols or address families,
		1510	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1511	used, and preference will be given to protocols mentioned earlier in the
		1512	list.
		1513
		1514	This variable can effectively be used for denial-of-service attacks
		1515	against local programs (e.g. when setuid), although the impact is likely
		1516	small, as the program has to handle conenction and other failures anyways.
		1517
		1518	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1519	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1520	- only support IPv4, never try to resolve or contact IPv6
		1521	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1522	IPv6, but prefer IPv6 over IPv4.
		1523
		1524	=item C<PERL_ANYEVENT_EDNS0>
		1525
		1526	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1527	for DNS. This extension is generally useful to reduce DNS traffic, but
		1528	some (broken) firewalls drop such DNS packets, which is why it is off by
		1529	default.
		1530
		1531	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1532	EDNS0 in its DNS requests.
		1533
		1534	=item C<PERL_ANYEVENT_MAX_FORKS>
		1535
		1536	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1537	will create in parallel.
		1538
		1539	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1540
		1541	The default value for the C<max_outstanding> parameter for the default DNS
		1542	resolver - this is the maximum number of parallel DNS requests that are
		1543	sent to the DNS server.
		1544
		1545	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1546
		1547	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1548	configuration) in the default resolver. When set to the empty string, no
		1549	default config will be used.
		1550
		1551	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1552
		1553	When neither C<ca_file> nor C<ca_path> was specified during
		1554	L<AnyEvent::TLS> context creation, and either of these environment
		1555	variables exist, they will be used to specify CA certificate locations
		1556	instead of a system-dependent default.
		1557
		1558	=back
732		1559
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1561
735	This is an advanced topic that you do not normally need to use AnyEvent in	1562	This is an advanced topic that you do not normally need to use AnyEvent in
736	a module. This section is only of use to event loop authors who want to	1563	a module. This section is only of use to event loop authors who want to
…		…
770		1597
771	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1598	I<rxvt-unicode> also cheats a bit by not providing blocking access to
772	condition variables: code blocking while waiting for a condition will	1599	condition variables: code blocking while waiting for a condition will
773	C<die>. This still works with most modules/usages, and blocking calls must	1600	C<die>. This still works with most modules/usages, and blocking calls must
774	not be done in an interactive application, so it makes sense.	1601	not be done in an interactive application, so it makes sense.
775
776	=head1 ENVIRONMENT VARIABLES
777
778	The following environment variables are used by this module:
779
780	=over 4
781
782	=item C<PERL_ANYEVENT_VERBOSE>
783
784	By default, AnyEvent will be completely silent except in fatal
785	conditions. You can set this environment variable to make AnyEvent more
786	talkative.
787
788	When set to C<1> or higher, causes AnyEvent to warn about unexpected
789	conditions, such as not being able to load the event model specified by
790	C<PERL_ANYEVENT_MODEL>.
791
792	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
793	model it chooses.
794
795	=item C<PERL_ANYEVENT_MODEL>
796
797	This can be used to specify the event model to be used by AnyEvent, before
798	autodetection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	and the resulting module name is loaded and if the load was successful,
801	used as event model. If it fails to load AnyEvent will proceed with
802	autodetection and -probing.
803
804	This functionality might change in future versions.
805
806	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
807	could start your program like this:
808
809	PERL_ANYEVENT_MODEL=Perl perl ...
810
811	=back
812		1602
813	=head1 EXAMPLE PROGRAM	1603	=head1 EXAMPLE PROGRAM
814		1604
815	The following program uses an I/O watcher to read data from STDIN, a timer	1605	The following program uses an I/O watcher to read data from STDIN, a timer
816	to display a message once per second, and a condition variable to quit the	1606	to display a message once per second, and a condition variable to quit the
…		…
825	poll => 'r',	1615	poll => 'r',
826	cb => sub {	1616	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1617	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1618	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1619	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1620	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1621	},
832	);	1622	);
833		1623
834	my $time_watcher; # can only be used once	1624	my $time_watcher; # can only be used once
835		1625
…		…
840	});	1630	});
841	}	1631	}
842		1632
843	new_timer; # create first timer	1633	new_timer; # create first timer
844		1634
845	$cv->wait; # wait until user enters /^q/i	1635	$cv->recv; # wait until user enters /^q/i
846		1636
847	=head1 REAL-WORLD EXAMPLE	1637	=head1 REAL-WORLD EXAMPLE
848		1638
849	Consider the L<Net::FCP> module. It features (among others) the following	1639	Consider the L<Net::FCP> module. It features (among others) the following
850	API calls, which are to freenet what HTTP GET requests are to http:	1640	API calls, which are to freenet what HTTP GET requests are to http:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1690	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1691	or die "connection or write error";
902	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1692	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
903		1693
904	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1694	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
905	result and signals any possible waiters that the request ahs finished:	1695	result and signals any possible waiters that the request has finished:
906		1696
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1697	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1698
909	if (end-of-file or data complete) {	1699	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1700	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1701	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1702	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1703	}
914		1704
915	The C<result> method, finally, just waits for the finished signal (if the	1705	The C<result> method, finally, just waits for the finished signal (if the
916	request was already finished, it doesn't wait, of course, and returns the	1706	request was already finished, it doesn't wait, of course, and returns the
917	data:	1707	data:
918		1708
919	$txn->{finished}->wait;	1709	$txn->{finished}->recv;
920	return $txn->{result};	1710	return $txn->{result};
921		1711
922	The actual code goes further and collects all errors (C<die>s, exceptions)	1712	The actual code goes further and collects all errors (C<die>s, exceptions)
923	that occured during request processing. The C<result> method detects	1713	that occurred during request processing. The C<result> method detects
924	whether an exception as thrown (it is stored inside the $txn object)	1714	whether an exception as thrown (it is stored inside the $txn object)
925	and just throws the exception, which means connection errors and other	1715	and just throws the exception, which means connection errors and other
926	problems get reported tot he code that tries to use the result, not in a	1716	problems get reported tot he code that tries to use the result, not in a
927	random callback.	1717	random callback.
928		1718
…		…
959		1749
960	my $quit = AnyEvent->condvar;	1750	my $quit = AnyEvent->condvar;
961		1751
962	$fcp->txn_client_get ($url)->cb (sub {	1752	$fcp->txn_client_get ($url)->cb (sub {
963	...	1753	...
964	$quit->broadcast;	1754	$quit->send;
965	});	1755	});
966		1756
967	$quit->wait;	1757	$quit->recv;
968		1758
969		1759
970	=head1 BENCHMARKS	1760	=head1 BENCHMARKS
971		1761
972	To give you an idea of the performance and overheads that AnyEvent adds	1762	To give you an idea of the performance and overheads that AnyEvent adds
…		…
974	of various event loops I prepared some benchmarks.	1764	of various event loops I prepared some benchmarks.
975		1765
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1766	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1767
978	Here is a benchmark of various supported event models used natively and	1768	Here is a benchmark of various supported event models used natively and
979	through anyevent. The benchmark creates a lot of timers (with a zero	1769	through AnyEvent. The benchmark creates a lot of timers (with a zero
980	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1770	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981	which it is), lets them fire exactly once and destroys them again.	1771	which it is), lets them fire exactly once and destroys them again.
982		1772
983	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1773	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
984	distribution.	1774	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1791	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1792	and memory usage is not included in the figures.
1003		1793
1004	I<invoke> is the time, in microseconds, used to invoke a simple	1794	I<invoke> is the time, in microseconds, used to invoke a simple
1005	callback. The callback simply counts down a Perl variable and after it was	1795	callback. The callback simply counts down a Perl variable and after it was
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1796	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1797	signal the end of this phase.
1008		1798
1009	I<destroy> is the time, in microseconds, that it takes to destroy a single	1799	I<destroy> is the time, in microseconds, that it takes to destroy a single
1010	watcher.	1800	watcher.
1011		1801
1012	=head3 Results	1802	=head3 Results
1013		1803
1014	name watchers bytes create invoke destroy comment	1804	name watchers bytes create invoke destroy comment
1015	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1805	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1016	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1806	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1017	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1807	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1018	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1808	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1019	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1809	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1020	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1810	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1811	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1812	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1021	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1813	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1022	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1814	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1023	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1815	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1024	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1816	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1025		1817
1026	=head3 Discussion	1818	=head3 Discussion
1027		1819
1028	The benchmark does I<not> measure scalability of the event loop very	1820	The benchmark does I<not> measure scalability of the event loop very
1029	well. For example, a select-based event loop (such as the pure perl one)	1821	well. For example, a select-based event loop (such as the pure perl one)
…		…
1054	performance becomes really bad with lots of file descriptors (and few of	1846	performance becomes really bad with lots of file descriptors (and few of
1055	them active), of course, but this was not subject of this benchmark.	1847	them active), of course, but this was not subject of this benchmark.
1056		1848
1057	The C<Event> module has a relatively high setup and callback invocation	1849	The C<Event> module has a relatively high setup and callback invocation
1058	cost, but overall scores in on the third place.	1850	cost, but overall scores in on the third place.
		1851
		1852	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1853	when using its pure perl backend.
1059		1854
1060	C<Glib>'s memory usage is quite a bit higher, but it features a	1855	C<Glib>'s memory usage is quite a bit higher, but it features a
1061	faster callback invocation and overall ends up in the same class as	1856	faster callback invocation and overall ends up in the same class as
1062	C<Event>. However, Glib scales extremely badly, doubling the number of	1857	C<Event>. However, Glib scales extremely badly, doubling the number of
1063	watchers increases the processing time by more than a factor of four,	1858	watchers increases the processing time by more than a factor of four,
…		…
1107		1902
1108	=back	1903	=back
1109		1904
1110	=head2 BENCHMARKING THE LARGE SERVER CASE	1905	=head2 BENCHMARKING THE LARGE SERVER CASE
1111		1906
1112	This benchmark atcually benchmarks the event loop itself. It works by	1907	This benchmark actually benchmarks the event loop itself. It works by
1113	creating a number of "servers": each server consists of a socketpair, a	1908	creating a number of "servers": each server consists of a socket pair, a
1114	timeout watcher that gets reset on activity (but never fires), and an I/O	1909	timeout watcher that gets reset on activity (but never fires), and an I/O
1115	watcher waiting for input on one side of the socket. Each time the socket	1910	watcher waiting for input on one side of the socket. Each time the socket
1116	watcher reads a byte it will write that byte to a random other "server".	1911	watcher reads a byte it will write that byte to a random other "server".
1117		1912
1118	The effect is that there will be a lot of I/O watchers, only part of which	1913	The effect is that there will be a lot of I/O watchers, only part of which
1119	are active at any one point (so there is a constant number of active	1914	are active at any one point (so there is a constant number of active
1120	fds for each loop iterstaion, but which fds these are is random). The	1915	fds for each loop iteration, but which fds these are is random). The
1121	timeout is reset each time something is read because that reflects how	1916	timeout is reset each time something is read because that reflects how
1122	most timeouts work (and puts extra pressure on the event loops).	1917	most timeouts work (and puts extra pressure on the event loops).
1123		1918
1124	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1919	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1125	(1%) are active. This mirrors the activity of large servers with many	1920	(1%) are active. This mirrors the activity of large servers with many
1126	connections, most of which are idle at any one point in time.	1921	connections, most of which are idle at any one point in time.
1127		1922
1128	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1923	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1129	distribution.	1924	distribution.
…		…
1131	=head3 Explanation of the columns	1926	=head3 Explanation of the columns
1132		1927
1133	I<sockets> is the number of sockets, and twice the number of "servers" (as	1928	I<sockets> is the number of sockets, and twice the number of "servers" (as
1134	each server has a read and write socket end).	1929	each server has a read and write socket end).
1135		1930
1136	I<create> is the time it takes to create a socketpair (which is	1931	I<create> is the time it takes to create a socket pair (which is
1137	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1932	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1138		1933
1139	I<request>, the most important value, is the time it takes to handle a	1934	I<request>, the most important value, is the time it takes to handle a
1140	single "request", that is, reading the token from the pipe and forwarding	1935	single "request", that is, reading the token from the pipe and forwarding
1141	it to another server. This includes deleting the old timeout and creating	1936	it to another server. This includes deleting the old timeout and creating
1142	a new one that moves the timeout into the future.	1937	a new one that moves the timeout into the future.
1143		1938
1144	=head3 Results	1939	=head3 Results
1145		1940
1146	name sockets create request	1941	name sockets create request
1147	EV 20000 69.01 11.16	1942	EV 20000 69.01 11.16
1148	Perl 20000 73.32 35.87	1943	Perl 20000 73.32 35.87
		1944	IOAsync 20000 157.00 98.14 epoll
		1945	IOAsync 20000 159.31 616.06 poll
1149	Event 20000 212.62 257.32	1946	Event 20000 212.62 257.32
1150	Glib 20000 651.16 1896.30	1947	Glib 20000 651.16 1896.30
1151	POE 20000 349.67 12317.24 uses POE::Loop::Event	1948	POE 20000 349.67 12317.24 uses POE::Loop::Event
1152		1949
1153	=head3 Discussion	1950	=head3 Discussion
1154		1951
1155	This benchmark I<does> measure scalability and overall performance of the	1952	This benchmark I<does> measure scalability and overall performance of the
1156	particular event loop.	1953	particular event loop.
…		…
1158	EV is again fastest. Since it is using epoll on my system, the setup time	1955	EV is again fastest. Since it is using epoll on my system, the setup time
1159	is relatively high, though.	1956	is relatively high, though.
1160		1957
1161	Perl surprisingly comes second. It is much faster than the C-based event	1958	Perl surprisingly comes second. It is much faster than the C-based event
1162	loops Event and Glib.	1959	loops Event and Glib.
		1960
		1961	IO::Async performs very well when using its epoll backend, and still quite
		1962	good compared to Glib when using its pure perl backend.
1163		1963
1164	Event suffers from high setup time as well (look at its code and you will	1964	Event suffers from high setup time as well (look at its code and you will
1165	understand why). Callback invocation also has a high overhead compared to	1965	understand why). Callback invocation also has a high overhead compared to
1166	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1966	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1167	uses select or poll in basically all documented configurations.	1967	uses select or poll in basically all documented configurations.
…		…
1214	speed most when you have lots of watchers, not when you only have a few of	2014	speed most when you have lots of watchers, not when you only have a few of
1215	them).	2015	them).
1216		2016
1217	EV is again fastest.	2017	EV is again fastest.
1218		2018
1219	Perl again comes second. It is noticably faster than the C-based event	2019	Perl again comes second. It is noticeably faster than the C-based event
1220	loops Event and Glib, although the difference is too small to really	2020	loops Event and Glib, although the difference is too small to really
1221	matter.	2021	matter.
1222		2022
1223	POE also performs much better in this case, but is is still far behind the	2023	POE also performs much better in this case, but is is still far behind the
1224	others.	2024	others.
…		…
1230	=item * C-based event loops perform very well with small number of	2030	=item * C-based event loops perform very well with small number of
1231	watchers, as the management overhead dominates.	2031	watchers, as the management overhead dominates.
1232		2032
1233	=back	2033	=back
1234		2034
		2035	=head2 THE IO::Lambda BENCHMARK
		2036
		2037	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2038	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2039	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2040	shouldn't come as a surprise to anybody). As such, the benchmark is
		2041	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2042	very optimal. But how would AnyEvent compare when used without the extra
		2043	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2044
		2045	The benchmark itself creates an echo-server, and then, for 500 times,
		2046	connects to the echo server, sends a line, waits for the reply, and then
		2047	creates the next connection. This is a rather bad benchmark, as it doesn't
		2048	test the efficiency of the framework or much non-blocking I/O, but it is a
		2049	benchmark nevertheless.
		2050
		2051	name runtime
		2052	Lambda/select 0.330 sec
		2053	+ optimized 0.122 sec
		2054	Lambda/AnyEvent 0.327 sec
		2055	+ optimized 0.138 sec
		2056	Raw sockets/select 0.077 sec
		2057	POE/select, components 0.662 sec
		2058	POE/select, raw sockets 0.226 sec
		2059	POE/select, optimized 0.404 sec
		2060
		2061	AnyEvent/select/nb 0.085 sec
		2062	AnyEvent/EV/nb 0.068 sec
		2063	+state machine 0.134 sec
		2064
		2065	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2066	benchmarks actually make blocking connects and use 100% blocking I/O,
		2067	defeating the purpose of an event-based solution. All of the newly
		2068	written AnyEvent benchmarks use 100% non-blocking connects (using
		2069	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2070	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2071	generally require a lot more bookkeeping and event handling than blocking
		2072	connects (which involve a single syscall only).
		2073
		2074	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2075	offers similar expressive power as POE and IO::Lambda, using conventional
		2076	Perl syntax. This means that both the echo server and the client are 100%
		2077	non-blocking, further placing it at a disadvantage.
		2078
		2079	As you can see, the AnyEvent + EV combination even beats the
		2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2081	backend easily beats IO::Lambda and POE.
		2082
		2083	And even the 100% non-blocking version written using the high-level (and
		2084	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2085	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2086	in a non-blocking way.
		2087
		2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2089	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2090	part of the IO::lambda distribution and were used without any changes.
		2091
		2092
		2093	=head1 SIGNALS
		2094
		2095	AnyEvent currently installs handlers for these signals:
		2096
		2097	=over 4
		2098
		2099	=item SIGCHLD
		2100
		2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2102	emulation for event loops that do not support them natively. Also, some
		2103	event loops install a similar handler.
		2104
		2105	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2106	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2107
		2108	=item SIGPIPE
		2109
		2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2111	when AnyEvent gets loaded.
		2112
		2113	The rationale for this is that AnyEvent users usually do not really depend
		2114	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2115	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2116	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2117	some random socket.
		2118
		2119	The rationale for installing a no-op handler as opposed to ignoring it is
		2120	that this way, the handler will be restored to defaults on exec.
		2121
		2122	Feel free to install your own handler, or reset it to defaults.
		2123
		2124	=back
		2125
		2126	=cut
		2127
		2128	undef $SIG{CHLD}
		2129	if $SIG{CHLD} eq 'IGNORE';
		2130
		2131	$SIG{PIPE} = sub { }
		2132	unless defined $SIG{PIPE};
1235		2133
1236	=head1 FORK	2134	=head1 FORK
1237		2135
1238	Most event libraries are not fork-safe. The ones who are usually are	2136	Most event libraries are not fork-safe. The ones who are usually are
1239	because they are so inefficient. Only L<EV> is fully fork-aware.	2137	because they rely on inefficient but fork-safe C<select> or C<poll>
		2138	calls. Only L<EV> is fully fork-aware.
1240		2139
1241	If you have to fork, you must either do so I<before> creating your first	2140	If you have to fork, you must either do so I<before> creating your first
1242	watcher OR you must not use AnyEvent at all in the child.	2141	watcher OR you must not use AnyEvent at all in the child.
1243		2142
1244		2143
…		…
1252	specified in the variable.	2151	specified in the variable.
1253		2152
1254	You can make AnyEvent completely ignore this variable by deleting it	2153	You can make AnyEvent completely ignore this variable by deleting it
1255	before the first watcher gets created, e.g. with a C<BEGIN> block:	2154	before the first watcher gets created, e.g. with a C<BEGIN> block:
1256		2155
1257	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2156	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1258		2157
1259	use AnyEvent;	2158	use AnyEvent;
		2159
		2160	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2161	be used to probe what backend is used and gain other information (which is
		2162	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2163	$ENV{PERL_ANYEVENT_STRICT}.
		2164
		2165	Note that AnyEvent will remove I<all> environment variables starting with
		2166	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2167	enabled.
		2168
		2169
		2170	=head1 BUGS
		2171
		2172	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2173	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2174	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2175	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2176	pronounced).
1260		2177
1261		2178
1262	=head1 SEE ALSO	2179	=head1 SEE ALSO
1263		2180
1264	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	2181	Utility functions: L<AnyEvent::Util>.
1265	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	2182
		2183	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1266	L<Event::Lib>, L<Qt>, L<POE>.	2184	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1267		2185
1268	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1269	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1270	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1271	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1272		2190
		2191	Non-blocking file handles, sockets, TCP clients and
		2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2193
		2194	Asynchronous DNS: L<AnyEvent::DNS>.
		2195
		2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2197	L<Coro::Event>,
		2198
1273	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2200	L<AnyEvent::HTTP>.
1274		2201
1275		2202
1276	=head1 AUTHOR	2203	=head1 AUTHOR
1277		2204
1278	Marc Lehmann <schmorp@schmorp.de>	2205	Marc Lehmann <schmorp@schmorp.de>
1279	http://home.schmorp.de/	2206	http://home.schmorp.de/
1280		2207
1281	=cut	2208	=cut
1282		2209
1283	1	2210	1
1284		2211

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines