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Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs.
Revision 1.366 by root, Wed Aug 17 02:02:38 2011 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
		42
		43	=head1 INTRODUCTION/TUTORIAL
		44
		45	This manpage is mainly a reference manual. If you are interested
		46	in a tutorial or some gentle introduction, have a look at the
		47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		58
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		60
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
27		63
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
30		66
31	First and foremost, I<AnyEvent is not an event model> itself, it only	67	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	68	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,	69	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,	70	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	71	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
37		74
38	The goal of AnyEvent is to offer module authors the ability to do event	75	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	76	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	77	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	78	module users into the same thing by forcing them to use the same event
42	model you use.	79	model you use.
43		80
44	For modules like POE or IO::Async (which is a total misnomer as it is	81	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	82	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	83	like joining a cult: After you join, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	84	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	85	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.	86	module are I<also> forced to use the same event loop you use.
50		87
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	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	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
54	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
55	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
56	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
57	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
58	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
59		96
60	In addition to being free of having to use I<the one and only true event	97	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	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	99	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	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	102	technically possible.
66		103
67	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
68	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
74	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
75	model, you should I<not> use this module.	112	model, you should I<not> use this module.
76		113
77	=head1 DESCRIPTION	114	=head1 DESCRIPTION
78		115
79	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
80	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
81	users to use the same event loop (as only a single event loop can coexist	118	module users to use a specific event loop implementation (since more
82	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
83		120
84	The interface itself is vaguely similar, but not identical to the L<Event>	121	The interface itself is vaguely similar, but not identical to the L<Event>
85	module.	122	module.
86		123
87	During the first call of any watcher-creation method, the module tries	124	During the first call of any watcher-creation method, the module tries
88	to detect the currently loaded event loop by probing whether one of the	125	to detect the currently loaded event loop by probing whether one of the
89	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
90	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	127	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
91	L<POE>. The first one found is used. If none are found, the module tries	128	found is used. If none are detected, the module tries to load the first
92	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	129	four modules in the order given; but note that if L<EV> is not
93	adaptor should always succeed) in the order given. The first one that can	130	available, the pure-perl L<AnyEvent::Loop> should always work, so
94	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
95	found, AnyEvent will fall back to a pure-perl event loop, which is not
96	very efficient, but should work everywhere.
97		132
98	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
99	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
100	that model the default. For example:	135	that model the default. For example:
101		136
…		…
103	use AnyEvent;	138	use AnyEvent;
104		139
105	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
106		141
107	The I<likely> means that, if any module loads another event model and	142	The I<likely> means that, if any module loads another event model and
108	starts using it, all bets are off. Maybe you should tell their authors to	143	starts using it, all bets are off - this case should be very rare though,
109	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
110		146
111	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
112	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	148	other event modules you can load it explicitly and enjoy the high
113	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
114		150
115	=head1 WATCHERS	151	=head1 WATCHERS
116		152
117	AnyEvent has the central concept of a I<watcher>, which is an object that	153	AnyEvent has the central concept of a I<watcher>, which is an object that
118	stores relevant data for each kind of event you are waiting for, such as	154	stores relevant data for each kind of event you are waiting for, such as
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	158	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	159	callback when the event occurs (of course, only when the event model
124	is in control).	160	is in control).
125		161
		162	Note that B<callbacks must not permanently change global variables>
		163	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		164	callbacks must not C<die> >>. The former is good programming practice in
		165	Perl and the latter stems from the fact that exception handling differs
		166	widely between event loops.
		167
126	To disable the watcher you have to destroy it (e.g. by setting the	168	To disable a watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	169	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	170	to it).
129		171
130	All watchers are created by calling a method on the C<AnyEvent> class.	172	All watchers are created by calling a method on the C<AnyEvent> class.
131		173
132	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	175	example), or need to refer to their watcher object in other ways.
134		176
135	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
136		178
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
139	undef $w;	181	undef $w;
140	});	182	});
141		183
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	184	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	185	my variables are only visible after the statement in which they are
144	declared.	186	declared.
145		187
146	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
147		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	196	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
150		198
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		200	for events (AnyEvent might or might not keep a reference to this file
		201	handle). Note that only file handles pointing to things for which
		202	non-blocking operation makes sense are allowed. This includes sockets,
		203	most character devices, pipes, fifos and so on, but not for example files
		204	or block devices.
		205
152	for events. C<poll> must be a string that is either C<r> or C<w>,	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
154	respectively. C<cb> is the callback to invoke each time the file handle	209	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		210
157	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
160		214
161	The I/O watcher might use the underlying file descriptor or a copy of it.	215	The I/O watcher might use the underlying file descriptor or a copy of it.
162	You must not close a file handle as long as any watcher is active on the	216	You must not close a file handle as long as any watcher is active on the
163	underlying file descriptor.	217	underlying file descriptor.
164		218
165	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	220	always use non-blocking calls when reading/writing from/to your file
167	handles.	221	handles.
168		222
169	Example:
170
171	# wait for readability of STDIN, then read a line and disable the watcher	223	Example: wait for readability of STDIN, then read a line and disable the
		224	watcher.
		225
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	226	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	227	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	228	warn "read: $input\n";
175	undef $w;	229	undef $w;
176	});	230	});
177		231
178	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
179		233
		234	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		235
		236	$w = AnyEvent->timer (
		237	after => <fractional_seconds>,
		238	interval => <fractional_seconds>,
		239	cb => <callback>,
		240	);
		241
180	You can create a time watcher by calling the C<< AnyEvent->timer >>	242	You can create a time watcher by calling the C<< AnyEvent->timer >>
181	method with the following mandatory arguments:	243	method with the following mandatory arguments:
182		244
183	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
184	supported) the callback should be invoked. C<cb> is the callback to invoke	246	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
186		248
187	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
190		252
191	The timer callback will be invoked at most once: if you want a repeating	253	The callback will normally be invoked only once. If you specify another
192	timer you have to create a new watcher (this is a limitation by both Tk	254	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	255	callback will be invoked regularly at that interval (in fractional
		256	seconds) after the first invocation. If C<interval> is specified with a
		257	false value, then it is treated as if it were not specified at all.
194		258
195	Example:	259	The callback will be rescheduled before invoking the callback, but no
		260	attempt is made to avoid timer drift in most backends, so the interval is
		261	only approximate.
196		262
197	# fire an event after 7.7 seconds	263	Example: fire an event after 7.7 seconds.
		264
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	266	warn "timeout\n";
200	});	267	});
201		268
202	# to cancel the timer:	269	# to cancel the timer:
203	undef $w;	270	undef $w;
204		271
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	272	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		273
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		275	warn "timeout\n";
213	};	276	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		277
218	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
219		279
220	There are two ways to handle timers: based on real time (relative, "fire	280	There are two ways to handle timers: based on real time (relative, "fire
221	in 10 seconds") and based on wallclock time (absolute, "fire at 12	281	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
223		283
224	While most event loops expect timers to specified in a relative way, they	284	While most event loops expect timers to specified in a relative way, they
225	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
226	"jumps", for example, when ntp decides to set your clock backwards from	286	"jumps", for example, when ntp decides to set your clock backwards from
227	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	287	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
228	fire "after" a second might actually take six years to finally fire.	288	fire "after a second" might actually take six years to finally fire.
229		289
230	AnyEvent cannot compensate for this. The only event loop that is conscious	290	AnyEvent cannot compensate for this. The only event loop that is conscious
231	about these issues is L<EV>, which offers both relative (ev_timer, based	291	of these issues is L<EV>, which offers both relative (ev_timer, based
232	on true relative time) and absolute (ev_periodic, based on wallclock time)	292	on true relative time) and absolute (ev_periodic, based on wallclock time)
233	timers.	293	timers.
234		294
235	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
236	AnyEvent API.	296	AnyEvent API.
…		…
243		303
244	This returns the "current wallclock time" as a fractional number of	304	This returns the "current wallclock time" as a fractional number of
245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>	305	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
246	return, and the result is guaranteed to be compatible with those).	306	return, and the result is guaranteed to be compatible with those).
247		307
248	It progresses independently of any event loop processing.	308	It progresses independently of any event loop processing, i.e. each call
249		309	will check the system clock, which usually gets updated frequently.
250	In almost all cases (in all cases if you don't care), this is the function
251	to call when you want to know the current time.
252		310
253	=item AnyEvent->now	311	=item AnyEvent->now
254		312
255	This also returns the "current wallclock time", but unlike C<time>, above,	313	This also returns the "current wallclock time", but unlike C<time>, above,
256	this value might change only once per event loop iteration, depending on	314	this value might change only once per event loop iteration, depending on
257	the event loop (most return the same time as C<time>, above). This is the	315	the event loop (most return the same time as C<time>, above). This is the
258	time that AnyEvent timers get scheduled against.	316	time that AnyEvent's timers get scheduled against.
		317
		318	I<In almost all cases (in all cases if you don't care), this is the
		319	function to call when you want to know the current time.>
		320
		321	This function is also often faster then C<< AnyEvent->time >>, and
		322	thus the preferred method if you want some timestamp (for example,
		323	L<AnyEvent::Handle> uses this to update its activity timeouts).
		324
		325	The rest of this section is only of relevance if you try to be very exact
		326	with your timing; you can skip it without a bad conscience.
259		327
260	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
261	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
262		330
263	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
264	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
265	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
266	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
267	after three seconds.	335	after three seconds.
268		336
269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will	337	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
270	both return C<501>, because that is the current time, and the timer will	338	both return C<501>, because that is the current time, and the timer will
271	be scheduled to fire at time=504 (C<501> + C<3>).	339	be scheduled to fire at time=504 (C<501> + C<3>).
272		340
273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current	341	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the	342	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
275	last event processing phase started. With L<EV>, your timer gets scheduled	343	last event processing phase started. With L<EV>, your timer gets scheduled
276	to run at time=503 (C<500> + C<3>).	344	to run at time=503 (C<500> + C<3>).
277		345
278	In one sense, L<Event::Lib> is more exact, as it uses the current time	346	In one sense, L<Event::Lib> is more exact, as it uses the current time
279	regardless of any delays introduced by event processing. However, most	347	regardless of any delays introduced by event processing. However, most
280	callbacks do not expect large delays in processing, so this causes a	348	callbacks do not expect large delays in processing, so this causes a
281	higher drift (and a lot more syscalls to get the current time).	349	higher drift (and a lot more system calls to get the current time).
282		350
283	In another sense, L<EV> is more exact, as your timer will be scheduled at	351	In another sense, L<EV> is more exact, as your timer will be scheduled at
284	the same time, regardless of how long event processing actually took.	352	the same time, regardless of how long event processing actually took.
285		353
286	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
287	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
289	account.	357	account.
290		358
		359	=item AnyEvent->now_update
		360
		361	Some event loops (such as L<EV> or L<AnyEvent::Loop>) cache the current
		362	time for each loop iteration (see the discussion of L<< AnyEvent->now >>,
		363	above).
		364
		365	When a callback runs for a long time (or when the process sleeps), then
		366	this "current" time will differ substantially from the real time, which
		367	might affect timers and time-outs.
		368
		369	When this is the case, you can call this method, which will update the
		370	event loop's idea of "current time".
		371
		372	A typical example would be a script in a web server (e.g. C<mod_perl>) -
		373	when mod_perl executes the script, then the event loop will have the wrong
		374	idea about the "current time" (being potentially far in the past, when the
		375	script ran the last time). In that case you should arrange a call to C<<
		376	AnyEvent->now_update >> each time the web server process wakes up again
		377	(e.g. at the start of your script, or in a handler).
		378
		379	Note that updating the time I<might> cause some events to be handled.
		380
291	=back	381	=back
292		382
293	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
294		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
295	You can watch for signals using a signal watcher, C<signal> is the signal	387	You can watch for signals using a signal watcher, C<signal> is the signal
296	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
297	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
298		390
299	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
300	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
301	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
302		394
…		…
304	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
305	that it might take a while until the signal gets handled by the process,	397	that it might take a while until the signal gets handled by the process,
306	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
307		399
308	The main advantage of using these watchers is that you can share a signal	400	The main advantage of using these watchers is that you can share a signal
309	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
310		403
311	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
312	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
313		407
314	Example: exit on SIGINT	408	Example: exit on SIGINT
315		409
316	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
317		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
318	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
319		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
320	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
321		454
322	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
323	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
324	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
325	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
326	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
327	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
328		469
329	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
330	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
331	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
332		473
333	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
334	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
335	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
336		480
337	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
338	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
339	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which case the latency and race
		488	problems mentioned in the description of signal watchers apply.
340		489
341	Example: fork a process and wait for it	490	Example: fork a process and wait for it
342		491
343	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
344		493
345	my $pid = fork or exit 5;	494	my $pid = fork or exit 5;
346		495
347	my $w = AnyEvent->child (	496	my $w = AnyEvent->child (
348	pid => $pid,	497	pid => $pid,
349	cb => sub {	498	cb => sub {
350	my ($pid, $status) = @_;	499	my ($pid, $status) = @_;
351	warn "pid $pid exited with status $status";	500	warn "pid $pid exited with status $status";
352	$done->send;	501	$done->send;
353	},	502	},
354	);	503	);
355		504
356	# do something else, then wait for process exit	505	# do something else, then wait for process exit
357	$done->recv;	506	$done->recv;
		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
358		547
359	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
360		554
361	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
362	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
363	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
364		558
365	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
366	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
367		561
368	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
369	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
370		566
371	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
372	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
373	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
374	becomes true.	570	becomes true, with the condition variable as the first argument (but not
		571	the results).
375		572
376	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
377	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
378	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
379	->send >> method).	576	->send >> method).
380		577
381	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
382	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
383	in time where multiple outstanding events have been processed. And yet	580
384	another way to call them is transactions - each condition variable can be	581	=over 4
385	used to represent a transaction, which finishes at some point and delivers	582
386	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
387		601
388	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
389	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
390	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
391	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
404		618
405	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
406	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
407	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
408	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
409	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
410		624
411	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
412	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
413	for the send to occur.	627	for the send to occur.
414		628
415	Example: wait for a timer.	629	Example: wait for a timer.
416		630
417	# wait till the result is ready	631	# condition: "wait till the timer is fired"
418	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
419		633
420	# do something such as adding a timer	634	# create the timer - we could wait for, say
421	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
422	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
423	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
424	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
425	after => 1,	639	after => 1,
426	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
427	);	641	);
428		642
429	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
430	# calls send	644	# calls ->send
431	$result_ready->recv;	645	$timer_fired->recv;
432		646
433	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
434	condition variables are also code references.	648	variables are also callable directly.
435		649
436	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
437	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
438	$done->recv;	652	$done->recv;
		653
		654	Example: Imagine an API that returns a condvar and doesn't support
		655	callbacks. This is how you make a synchronous call, for example from
		656	the main program:
		657
		658	use AnyEvent::CouchDB;
		659
		660	...
		661
		662	my @info = $couchdb->info->recv;
		663
		664	And this is how you would just set a callback to be called whenever the
		665	results are available:
		666
		667	$couchdb->info->cb (sub {
		668	my @info = $_[0]->recv;
		669	});
439		670
440	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
441		672
442	These methods should only be used by the producing side, i.e. the	673	These methods should only be used by the producing side, i.e. the
443	code/module that eventually sends the signal. Note that it is also	674	code/module that eventually sends the signal. Note that it is also
…		…
456	immediately from within send.	687	immediately from within send.
457		688
458	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
459	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
460		691
461	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
462	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
463	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
464	overloading, so as tempting as it may be, passing a condition variable
465	instead of a callback does not work. Both the pure perl and EV loops
466	support overloading, however, as well as all functions that use perl to
467	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
468	example).
469		695
470	=item $cv->croak ($error)	696	=item $cv->croak ($error)
471		697
472	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
473	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
474		700
475	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
476	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
477		707
478	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
479		709
480	=item $cv->end	710	=item $cv->end
481
482	These two methods are EXPERIMENTAL and MIGHT CHANGE.
483		711
484	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
485	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
486	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
487		715
488	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
489	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
490	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
491	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
492	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
493		722
494	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
495		730
496	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
497		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
498	my %result;	757	my %result;
499	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
500		759
501	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
502	$cv->begin;	761	$cv->begin;
503	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
504	$result{$host} = ...;	763	$result{$host} = ...;
…		…
519	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
520	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
521	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
522	doesn't execute once).	781	doesn't execute once).
523		782
524	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
525	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
526	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
527	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
528		788
529	=back	789	=back
530		790
531	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
532		792
…		…
536	=over 4	796	=over 4
537		797
538	=item $cv->recv	798	=item $cv->recv
539		799
540	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
541	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
542	normally.	802	normally.
543		803
544	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
545	will return immediately.	805	will return immediately.
546		806
…		…
548	function will call C<croak>.	808	function will call C<croak>.
549		809
550	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
551	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
552		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
553	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
554	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
555	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
556	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
557	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
558	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
559	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
560		827
561	Another reason I<never> to C<< ->recv >> in a module is that you cannot
562	sensibly have two C<< ->recv >>'s in parallel, as that would require
563	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
564	can supply.
565
566	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
567	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
568	versions and also integrates coroutines into AnyEvent, making blocking
569	C<< ->recv >> calls perfectly safe as long as they are done from another
570	coroutine (one that doesn't run the event loop).
571
572	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
573	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
574	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
575	waits otherwise.	831	waits otherwise.
576		832
577	=item $bool = $cv->ready	833	=item $bool = $cv->ready
578		834
579	Returns true when the condition is "true", i.e. whether C<send> or	835	Returns true when the condition is "true", i.e. whether C<send> or
580	C<croak> have been called.	836	C<croak> have been called.
581		837
582	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
583		839
584	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
585	replaces it before doing so.	841	replaces it before doing so.
586		842
587	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
588	C<send> or C<croak> are called. Calling C<recv> inside the callback	844	C<send> or C<croak> are called, with the only argument being the
		845	condition variable itself. If the condition is already true, the
		846	callback is called immediately when it is set. Calling C<recv> inside
589	or at any later time is guaranteed not to block.	847	the callback or at any later time is guaranteed not to block.
590		848
591	=back	849	=back
592		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
593	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
594		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
595	=over 4	919	=over 4
596		920
597	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
598		922
599	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
600	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
601	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
602	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
603	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
604		930	will be C<urxvt::anyevent>).
605	The known classes so far are:
606
607	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
608	AnyEvent::Impl::Event based on Event, second best choice.
609	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
610	AnyEvent::Impl::Glib based on Glib, third-best choice.
611	AnyEvent::Impl::Tk based on Tk, very bad choice.
612	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
614	AnyEvent::Impl::POE based on POE, not generic enough for full support.
615
616	There is no support for WxWidgets, as WxWidgets has no support for
617	watching file handles. However, you can use WxWidgets through the
618	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
619	second, which was considered to be too horrible to even consider for
620	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
621	it's adaptor.
622
623	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
624	autodetecting them.
625		931
626	=item AnyEvent::detect	932	=item AnyEvent::detect
627		933
628	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
629	if necessary. You should only call this function right before you would	935	if necessary. You should only call this function right before you would
630	have created an AnyEvent watcher anyway, that is, as late as possible at	936	have created an AnyEvent watcher anyway, that is, as late as possible at
631	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
632		945
633	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
634		947
635	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
636	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
637		961
638	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
639	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
640	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
641		982
642	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
643		984
644	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
645	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
646	the event loop has been chosen.	987	after the event loop has been chosen.
647		988
648	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
649	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
650	and the array will be ignored.	991	array will be ignored.
651		992
652	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
		1053
		1054	=item AnyEvent::log $level, $msg[, @args]
		1055
		1056	Log the given C<$msg> at the given C<$level>.
		1057
		1058	Loads AnyEvent::Log on first use and calls C<AnyEvent::Log::log> -
		1059	consequently, look at the L<AnyEvent::Log> documentation for details.
653		1060
654	=back	1061	=back
655		1062
656	=head1 WHAT TO DO IN A MODULE	1063	=head1 WHAT TO DO IN A MODULE
657		1064
…		…
668	because it will stall the whole program, and the whole point of using	1075	because it will stall the whole program, and the whole point of using
669	events is to stay interactive.	1076	events is to stay interactive.
670		1077
671	It is fine, however, to call C<< ->recv >> when the user of your module	1078	It is fine, however, to call C<< ->recv >> when the user of your module
672	requests it (i.e. if you create a http request object ad have a method	1079	requests it (i.e. if you create a http request object ad have a method
673	called C<results> that returns the results, it should call C<< ->recv >>	1080	called C<results> that returns the results, it may call C<< ->recv >>
674	freely, as the user of your module knows what she is doing. always).	1081	freely, as the user of your module knows what she is doing. Always).
675		1082
676	=head1 WHAT TO DO IN THE MAIN PROGRAM	1083	=head1 WHAT TO DO IN THE MAIN PROGRAM
677		1084
678	There will always be a single main program - the only place that should	1085	There will always be a single main program - the only place that should
679	dictate which event model to use.	1086	dictate which event model to use.
680		1087
681	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1088	If the program is not event-based, it need not do anything special, even
682	do anything special (it does not need to be event-based) and let AnyEvent	1089	when it depends on a module that uses an AnyEvent. If the program itself
683	decide which implementation to chose if some module relies on it.	1090	uses AnyEvent, but does not care which event loop is used, all it needs
		1091	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1092	available loop implementation.
684		1093
685	If the main program relies on a specific event model - for example, in	1094	If the main program relies on a specific event model - for example, in
686	Gtk2 programs you have to rely on the Glib module - you should load the	1095	Gtk2 programs you have to rely on the Glib module - you should load the
687	event module before loading AnyEvent or any module that uses it: generally	1096	event module before loading AnyEvent or any module that uses it: generally
688	speaking, you should load it as early as possible. The reason is that	1097	speaking, you should load it as early as possible. The reason is that
689	modules might create watchers when they are loaded, and AnyEvent will	1098	modules might create watchers when they are loaded, and AnyEvent will
690	decide on the event model to use as soon as it creates watchers, and it	1099	decide on the event model to use as soon as it creates watchers, and it
691	might chose the wrong one unless you load the correct one yourself.	1100	might choose the wrong one unless you load the correct one yourself.
692		1101
693	You can chose to use a pure-perl implementation by loading the	1102	You can chose to use a pure-perl implementation by loading the
694	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1103	C<AnyEvent::Loop> module, which gives you similar behaviour
695	everywhere, but letting AnyEvent chose the model is generally better.	1104	everywhere, but letting AnyEvent chose the model is generally better.
696		1105
697	=head2 MAINLOOP EMULATION	1106	=head2 MAINLOOP EMULATION
698		1107
699	Sometimes (often for short test scripts, or even standalone programs who	1108	Sometimes (often for short test scripts, or even standalone programs who
…		…
712		1121
713		1122
714	=head1 OTHER MODULES	1123	=head1 OTHER MODULES
715		1124
716	The following is a non-exhaustive list of additional modules that use	1125	The following is a non-exhaustive list of additional modules that use
717	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1126	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
718	in the same program. Some of the modules come with AnyEvent, some are	1127	modules and other event loops in the same program. Some of the modules
719	available via CPAN.	1128	come as part of AnyEvent, the others are available via CPAN.
720		1129
721	=over 4	1130	=over 4
722		1131
723	=item L<AnyEvent::Util>	1132	=item L<AnyEvent::Util>
724		1133
725	Contains various utility functions that replace often-used but blocking	1134	Contains various utility functions that replace often-used blocking
726	functions such as C<inet_aton> by event-/callback-based versions.	1135	functions such as C<inet_aton> with event/callback-based versions.
727
728	=item L<AnyEvent::Handle>
729
730	Provide read and write buffers and manages watchers for reads and writes.
731		1136
732	=item L<AnyEvent::Socket>	1137	=item L<AnyEvent::Socket>
733		1138
734	Provides various utility functions for (internet protocol) sockets,	1139	Provides various utility functions for (internet protocol) sockets,
735	addresses and name resolution. Also functions to create non-blocking tcp	1140	addresses and name resolution. Also functions to create non-blocking tcp
736	connections or tcp servers, with IPv6 and SRV record support and more.	1141	connections or tcp servers, with IPv6 and SRV record support and more.
737		1142
		1143	=item L<AnyEvent::Handle>
		1144
		1145	Provide read and write buffers, manages watchers for reads and writes,
		1146	supports raw and formatted I/O, I/O queued and fully transparent and
		1147	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1148
738	=item L<AnyEvent::DNS>	1149	=item L<AnyEvent::DNS>
739		1150
740	Provides rich asynchronous DNS resolver capabilities.	1151	Provides rich asynchronous DNS resolver capabilities.
741		1152
		1153	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1154
		1155	Implement event-based interfaces to the protocols of the same name (for
		1156	the curious, IGS is the International Go Server and FCP is the Freenet
		1157	Client Protocol).
		1158
		1159	=item L<AnyEvent::Handle::UDP>
		1160
		1161	Here be danger!
		1162
		1163	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1164	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1165	its use of a stream-based API with a protocol that isn't streamable, that
		1166	the only way to improve it is to delete it.
		1167
		1168	It features data corruption (but typically only under load) and general
		1169	confusion. On top, the author is not only clueless about UDP but also
		1170	fact-resistant - some gems of his understanding: "connect doesn't work
		1171	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1172	packets", "I don't need to implement proper error checking as UDP doesn't
		1173	support error checking" and so on - he doesn't even understand what's
		1174	wrong with his module when it is explained to him.
		1175
		1176	=item L<AnyEvent::DBI>
		1177
		1178	Executes L<DBI> requests asynchronously in a proxy process for you,
		1179	notifying you in an event-based way when the operation is finished.
		1180
		1181	=item L<AnyEvent::AIO>
		1182
		1183	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1184	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1185	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1186	file I/O, and much more.
		1187
742	=item L<AnyEvent::HTTPD>	1188	=item L<AnyEvent::HTTPD>
743		1189
744	Provides a simple web application server framework.	1190	A simple embedded webserver.
745		1191
746	=item L<AnyEvent::FastPing>	1192	=item L<AnyEvent::FastPing>
747		1193
748	The fastest ping in the west.	1194	The fastest ping in the west.
749		1195
750	=item L<Net::IRC3>
751
752	AnyEvent based IRC client module family.
753
754	=item L<Net::XMPP2>
755
756	AnyEvent based XMPP (Jabber protocol) module family.
757
758	=item L<Net::FCP>
759
760	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
761	of AnyEvent.
762
763	=item L<Event::ExecFlow>
764
765	High level API for event-based execution flow control.
766
767	=item L<Coro>	1196	=item L<Coro>
768		1197
769	Has special support for AnyEvent via L<Coro::AnyEvent>.	1198	Has special support for AnyEvent via L<Coro::AnyEvent>.
770		1199
771	=item L<AnyEvent::AIO>, L<IO::AIO>
772
773	Truly asynchronous I/O, should be in the toolbox of every event
774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
775	together.
776
777	=item L<AnyEvent::BDB>, L<BDB>
778
779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
780	IO::AIO and AnyEvent together.
781
782	=item L<IO::Lambda>
783
784	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
785
786	=back	1200	=back
787		1201
788	=cut	1202	=cut
789		1203
790	package AnyEvent;	1204	package AnyEvent;
791		1205
792	no warnings;	1206	# basically a tuned-down version of common::sense
793	use strict;	1207	sub common_sense {
		1208	# from common:.sense 3.4
		1209	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1210	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1211	$^H |= 0x00000600;
		1212	}
794		1213
		1214	BEGIN { AnyEvent::common_sense }
		1215
795	use Carp;	1216	use Carp ();
796		1217
797	our $VERSION = '4.05';	1218	our $VERSION = '6.01';
798	our $MODEL;	1219	our $MODEL;
799		1220
800	our $AUTOLOAD;
801	our @ISA;	1221	our @ISA;
802		1222
803	our @REGISTRY;	1223	our @REGISTRY;
804		1224
805	our $WIN32;	1225	our $VERBOSE;
806		1226
807	BEGIN {	1227	BEGIN {
808	my $win32 = ! ! ($^O =~ /mswin32/i);	1228	require "AnyEvent/constants.pl";
809	eval "sub WIN32(){ $win32 }";
810	}
811		1229
		1230	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1231
		1232	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1233	if ${^TAINT};
		1234
812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1235	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1236	}
		1237
		1238	our $MAX_SIGNAL_LATENCY = 10;
813		1239
814	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1240	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
815		1241
816	{	1242	{
817	my $idx;	1243	my $idx;
818	$PROTOCOL{$_} = ++$idx	1244	$PROTOCOL{$_} = ++$idx
819	for reverse split /\s*,\s*/,	1245	for reverse split /\s*,\s*/,
820	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1246	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
821	}	1247	}
822		1248
		1249	our @post_detect;
		1250
		1251	sub post_detect(&) {
		1252	my ($cb) = @_;
		1253
		1254	push @post_detect, $cb;
		1255
		1256	defined wantarray
		1257	? bless \$cb, "AnyEvent::Util::postdetect"
		1258	: ()
		1259	}
		1260
		1261	sub AnyEvent::Util::postdetect::DESTROY {
		1262	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1263	}
		1264
		1265	our $POSTPONE_W;
		1266	our @POSTPONE;
		1267
		1268	sub _postpone_exec {
		1269	undef $POSTPONE_W;
		1270
		1271	&{ shift @POSTPONE }
		1272	while @POSTPONE;
		1273	}
		1274
		1275	sub postpone(&) {
		1276	push @POSTPONE, shift;
		1277
		1278	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1279
		1280	()
		1281	}
		1282
		1283	sub log($$;@) {
		1284	require AnyEvent::Log;
		1285	# AnyEvent::Log overwrites this function
		1286	goto &log;
		1287	}
		1288
823	my @models = (	1289	our @models = (
824	[EV:: => AnyEvent::Impl::EV::],	1290	[EV:: => AnyEvent::Impl::EV:: , 1],
825	[Event:: => AnyEvent::Impl::Event::],	1291	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
826	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
827	# everything below here will not be autoprobed	1292	# everything below here will not (normally) be autoprobed
828	# as the pureperl backend should work everywhere	1293	# as the pure perl backend should work everywhere
829	# and is usually faster	1294	# and is usually faster
		1295	[Event:: => AnyEvent::Impl::Event::, 1],
		1296	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1297	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1298	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
830	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1299	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
831	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1300	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1301	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
835	[Wx:: => AnyEvent::Impl::POE::],	1302	[Wx:: => AnyEvent::Impl::POE::],
836	[Prima:: => AnyEvent::Impl::POE::],	1303	[Prima:: => AnyEvent::Impl::POE::],
		1304	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1305	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1306	[FLTK:: => AnyEvent::Impl::FLTK2::],
837	);	1307	);
838		1308
839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1309	our @isa_hook;
840		1310
841	our @post_detect;	1311	sub _isa_set {
		1312	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
842		1313
		1314	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1315	for 1 .. $#pkg;
		1316
		1317	grep $_ && $_->[1], @isa_hook
		1318	and AE::_reset ();
		1319	}
		1320
		1321	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1322	sub _isa_hook($$;$) {
		1323	my ($i, $pkg, $reset_ae) = @_;
		1324
		1325	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1326
		1327	_isa_set;
		1328	}
		1329
		1330	# all autoloaded methods reserve the complete glob, not just the method slot.
		1331	# due to bugs in perls method cache implementation.
		1332	our @methods = qw(io timer time now now_update signal child idle condvar);
		1333
843	sub post_detect(&) {	1334	sub detect() {
844	my ($cb) = @_;	1335	return $MODEL if $MODEL; # some programs keep references to detect
845		1336
846	if ($MODEL) {	1337	local $!; # for good measure
847	$cb->();	1338	local $SIG{__DIE__}; # we use eval
848		1339
849	1	1340	# free some memory
		1341	*detect = sub () { $MODEL };
		1342	# undef &func doesn't correctly update the method cache. grmbl.
		1343	# so we delete the whole glob. grmbl.
		1344	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1345	# a glob with an active sub. hrm. i hope it works, but perl is
		1346	# usually buggy in this department. sigh.
		1347	delete @{"AnyEvent::"}{@methods};
		1348	undef @methods;
		1349
		1350	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1351	my $model = $1;
		1352	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1353	if (eval "require $model") {
		1354	$MODEL = $model;
		1355	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it."
		1356	if $VERBOSE >= 7;
850	} else {	1357	} else {
851	push @post_detect, $cb;	1358	AnyEvent::log warn => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
852		1359	}
853	defined wantarray
854	? bless \$cb, "AnyEvent::Util::PostDetect"
855	: ()
856	}	1360	}
857	}
858		1361
859	sub AnyEvent::Util::PostDetect::DESTROY {	1362	# check for already loaded models
860	@post_detect = grep $_ != ${$_[0]}, @post_detect;
861	}
862
863	sub detect() {
864	unless ($MODEL) {	1363	unless ($MODEL) {
865	no strict 'refs';	1364	for (@REGISTRY, @models) {
866	local $SIG{__DIE__};	1365	my ($package, $model) = @$_;
867		1366	if (${"$package\::VERSION"} > 0) {
868	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
869	my $model = "AnyEvent::Impl::$1";
870	if (eval "require $model") {	1367	if (eval "require $model") {
871	$MODEL = $model;	1368	$MODEL = $model;
872	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1369	AnyEvent::log 7 => "autodetected model '$model', using it."
873	} else {	1370	if $VERBOSE >= 7;
874	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1371	last;
		1372	}
875	}	1373	}
876	}	1374	}
877		1375
878	# check for already loaded models
879	unless ($MODEL) {	1376	unless ($MODEL) {
		1377	# try to autoload a model
880	for (@REGISTRY, @models) {	1378	for (@REGISTRY, @models) {
881	my ($package, $model) = @$_;	1379	my ($package, $model, $autoload) = @$_;
		1380	if (
		1381	$autoload
		1382	and eval "require $package"
882	if (${"$package\::VERSION"} > 0) {	1383	and ${"$package\::VERSION"} > 0
883	if (eval "require $model") {	1384	and eval "require $model"
		1385	) {
884	$MODEL = $model;	1386	$MODEL = $model;
885	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1387	AnyEvent::log 7 => "autoloaded model '$model', using it."
		1388	if $VERBOSE >= 7;
886	last;	1389	last;
887	}
888	}	1390	}
889	}	1391	}
890		1392
891	unless ($MODEL) {	1393	$MODEL
892	# try to load a model	1394	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
		1395	}
		1396	}
893		1397
894	for (@REGISTRY, @models) {	1398	# free memory only needed for probing
895	my ($package, $model) = @$_;	1399	undef @models;
896	if (eval "require $package"	1400	undef @REGISTRY;
897	and ${"$package\::VERSION"} > 0	1401
898	and eval "require $model") {	1402	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
899	$MODEL = $model;	1403
900	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1404	# now nuke some methods that are overridden by the backend.
		1405	# SUPER usage is not allowed in these.
		1406	for (qw(time signal child idle)) {
		1407	undef &{"AnyEvent::Base::$_"}
		1408	if defined &{"$MODEL\::$_"};
		1409	}
		1410
		1411	_isa_set;
		1412
		1413	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1414	require AnyEvent::Strict;
		1415	}
		1416
		1417	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1418	require AnyEvent::Debug;
		1419	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1420	}
		1421
		1422	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1423	require AnyEvent::Socket;
		1424	require AnyEvent::Debug;
		1425
		1426	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1427	$shell =~ s/\$\$/$$/g;
		1428
		1429	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1430	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1431	}
		1432
		1433	(shift @post_detect)->() while @post_detect;
		1434	undef @post_detect;
		1435
		1436	*post_detect = sub(&) {
		1437	shift->();
		1438
		1439	undef
		1440	};
		1441
		1442	$MODEL
		1443	}
		1444
		1445	for my $name (@methods) {
		1446	*$name = sub {
		1447	detect;
		1448	# we use goto because
		1449	# a) it makes the thunk more transparent
		1450	# b) it allows us to delete the thunk later
		1451	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1452	};
		1453	}
		1454
		1455	# utility function to dup a filehandle. this is used by many backends
		1456	# to support binding more than one watcher per filehandle (they usually
		1457	# allow only one watcher per fd, so we dup it to get a different one).
		1458	sub _dupfh($$;$$) {
		1459	my ($poll, $fh, $r, $w) = @_;
		1460
		1461	# cygwin requires the fh mode to be matching, unix doesn't
		1462	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1463
		1464	open my $fh2, $mode, $fh
		1465	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1466
		1467	# we assume CLOEXEC is already set by perl in all important cases
		1468
		1469	($fh2, $rw)
		1470	}
		1471
		1472	=head1 SIMPLIFIED AE API
		1473
		1474	Starting with version 5.0, AnyEvent officially supports a second, much
		1475	simpler, API that is designed to reduce the calling, typing and memory
		1476	overhead by using function call syntax and a fixed number of parameters.
		1477
		1478	See the L<AE> manpage for details.
		1479
		1480	=cut
		1481
		1482	package AE;
		1483
		1484	our $VERSION = $AnyEvent::VERSION;
		1485
		1486	sub _reset() {
		1487	eval q{
		1488	# fall back to the main API by default - backends and AnyEvent::Base
		1489	# implementations can overwrite these.
		1490
		1491	sub io($$$) {
		1492	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1493	}
		1494
		1495	sub timer($$$) {
		1496	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1497	}
		1498
		1499	sub signal($$) {
		1500	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1501	}
		1502
		1503	sub child($$) {
		1504	AnyEvent->child (pid => $_[0], cb => $_[1])
		1505	}
		1506
		1507	sub idle($) {
		1508	AnyEvent->idle (cb => $_[0]);
		1509	}
		1510
		1511	sub cv(;&) {
		1512	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1513	}
		1514
		1515	sub now() {
		1516	AnyEvent->now
		1517	}
		1518
		1519	sub now_update() {
		1520	AnyEvent->now_update
		1521	}
		1522
		1523	sub time() {
		1524	AnyEvent->time
		1525	}
		1526
		1527	*postpone = \&AnyEvent::postpone;
		1528	*log = \&AnyEvent::log;
		1529	};
		1530	die if $@;
		1531	}
		1532
		1533	BEGIN { _reset }
		1534
		1535	package AnyEvent::Base;
		1536
		1537	# default implementations for many methods
		1538
		1539	sub time {
		1540	eval q{ # poor man's autoloading {}
		1541	# probe for availability of Time::HiRes
		1542	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1543	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy."
		1544	if $AnyEvent::VERBOSE >= 8;
		1545	*time = sub { Time::HiRes::time () };
		1546	*AE::time = \& Time::HiRes::time ;
		1547	# if (eval "use POSIX (); (POSIX::times())...
		1548	} else {
		1549	AnyEvent::log critical => "using built-in time(), WARNING, no sub-second resolution!";
		1550	*time = sub { CORE::time };
		1551	*AE::time = sub (){ CORE::time };
		1552	}
		1553
		1554	*now = \&time;
		1555	};
		1556	die if $@;
		1557
		1558	&time
		1559	}
		1560
		1561	*now = \&time;
		1562	sub now_update { }
		1563
		1564	sub _poll {
		1565	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1566	}
		1567
		1568	# default implementation for ->condvar
		1569	# in fact, the default should not be overwritten
		1570
		1571	sub condvar {
		1572	eval q{ # poor man's autoloading {}
		1573	*condvar = sub {
		1574	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1575	};
		1576
		1577	*AE::cv = sub (;&) {
		1578	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1579	};
		1580	};
		1581	die if $@;
		1582
		1583	&condvar
		1584	}
		1585
		1586	# default implementation for ->signal
		1587
		1588	our $HAVE_ASYNC_INTERRUPT;
		1589
		1590	sub _have_async_interrupt() {
		1591	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1592	&& eval "use Async::Interrupt 1.02 (); 1")
		1593	unless defined $HAVE_ASYNC_INTERRUPT;
		1594
		1595	$HAVE_ASYNC_INTERRUPT
		1596	}
		1597
		1598	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1599	our (%SIG_ASY, %SIG_ASY_W);
		1600	our ($SIG_COUNT, $SIG_TW);
		1601
		1602	# install a dummy wakeup watcher to reduce signal catching latency
		1603	# used by Impls
		1604	sub _sig_add() {
		1605	unless ($SIG_COUNT++) {
		1606	# try to align timer on a full-second boundary, if possible
		1607	my $NOW = AE::now;
		1608
		1609	$SIG_TW = AE::timer
		1610	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1611	$MAX_SIGNAL_LATENCY,
		1612	sub { } # just for the PERL_ASYNC_CHECK
		1613	;
		1614	}
		1615	}
		1616
		1617	sub _sig_del {
		1618	undef $SIG_TW
		1619	unless --$SIG_COUNT;
		1620	}
		1621
		1622	our $_sig_name_init; $_sig_name_init = sub {
		1623	eval q{ # poor man's autoloading {}
		1624	undef $_sig_name_init;
		1625
		1626	if (_have_async_interrupt) {
		1627	*sig2num = \&Async::Interrupt::sig2num;
		1628	*sig2name = \&Async::Interrupt::sig2name;
		1629	} else {
		1630	require Config;
		1631
		1632	my %signame2num;
		1633	@signame2num{ split ' ', $Config::Config{sig_name} }
		1634	= split ' ', $Config::Config{sig_num};
		1635
		1636	my @signum2name;
		1637	@signum2name[values %signame2num] = keys %signame2num;
		1638
		1639	*sig2num = sub($) {
		1640	$_[0] > 0 ? shift : $signame2num{+shift}
		1641	};
		1642	*sig2name = sub ($) {
		1643	$_[0] > 0 ? $signum2name[+shift] : shift
		1644	};
		1645	}
		1646	};
		1647	die if $@;
		1648	};
		1649
		1650	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1651	sub sig2name($) { &$_sig_name_init; &sig2name }
		1652
		1653	sub signal {
		1654	eval q{ # poor man's autoloading {}
		1655	# probe for availability of Async::Interrupt
		1656	if (_have_async_interrupt) {
		1657	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling."
		1658	if $AnyEvent::VERBOSE >= 8;
		1659
		1660	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1661	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1662
		1663	} else {
		1664	AnyEvent::log 8 => "using emulated perl signal handling with latency timer."
		1665	if $AnyEvent::VERBOSE >= 8;
		1666
		1667	if (AnyEvent::WIN32) {
		1668	require AnyEvent::Util;
		1669
		1670	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1671	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1672	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1673	} else {
		1674	pipe $SIGPIPE_R, $SIGPIPE_W;
		1675	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1676	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1677
		1678	# not strictly required, as $^F is normally 2, but let's make sure...
		1679	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1680	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1681	}
		1682
		1683	$SIGPIPE_R
		1684	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1685
		1686	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1687	}
		1688
		1689	*signal = $HAVE_ASYNC_INTERRUPT
		1690	? sub {
		1691	my (undef, %arg) = @_;
		1692
		1693	# async::interrupt
		1694	my $signal = sig2num $arg{signal};
		1695	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1696
		1697	$SIG_ASY{$signal} ||= new Async::Interrupt
		1698	cb => sub { undef $SIG_EV{$signal} },
		1699	signal => $signal,
		1700	pipe => [$SIGPIPE_R->filenos],
		1701	pipe_autodrain => 0,
		1702	;
		1703
		1704	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1705	}
		1706	: sub {
		1707	my (undef, %arg) = @_;
		1708
		1709	# pure perl
		1710	my $signal = sig2name $arg{signal};
		1711	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1712
		1713	$SIG{$signal} ||= sub {
901	last;	1714	local $!;
		1715	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1716	undef $SIG_EV{$signal};
902	}	1717	};
		1718
		1719	# can't do signal processing without introducing races in pure perl,
		1720	# so limit the signal latency.
		1721	_sig_add;
		1722
		1723	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1724	}
		1725	;
		1726
		1727	*AnyEvent::Base::signal::DESTROY = sub {
		1728	my ($signal, $cb) = @{$_[0]};
		1729
		1730	_sig_del;
		1731
		1732	delete $SIG_CB{$signal}{$cb};
		1733
		1734	$HAVE_ASYNC_INTERRUPT
		1735	? delete $SIG_ASY{$signal}
		1736	: # delete doesn't work with older perls - they then
		1737	# print weird messages, or just unconditionally exit
		1738	# instead of getting the default action.
		1739	undef $SIG{$signal}
		1740	unless keys %{ $SIG_CB{$signal} };
		1741	};
		1742
		1743	*_signal_exec = sub {
		1744	$HAVE_ASYNC_INTERRUPT
		1745	? $SIGPIPE_R->drain
		1746	: sysread $SIGPIPE_R, (my $dummy), 9;
		1747
		1748	while (%SIG_EV) {
		1749	for (keys %SIG_EV) {
		1750	delete $SIG_EV{$_};
		1751	&$_ for values %{ $SIG_CB{$_} || {} };
903	}	1752	}
904
905	$MODEL
906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
907	}	1753	}
908	}	1754	};
909
910	unshift @ISA, $MODEL;
911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
912
913	(shift @post_detect)->() while @post_detect;
914	}
915
916	$MODEL
917	}
918
919	sub AUTOLOAD {
920	(my $func = $AUTOLOAD) =~ s/.*://;
921
922	$method{$func}
923	or croak "$func: not a valid method for AnyEvent objects";
924
925	detect unless $MODEL;
926
927	my $class = shift;
928	$class->$func (@_);
929	}
930
931	package AnyEvent::Base;
932
933	# default implementation for now and time
934
935	use Time::HiRes ();
936
937	sub time { Time::HiRes::time }
938	sub now { Time::HiRes::time }
939
940	# default implementation for ->condvar
941
942	sub condvar {
943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
944	}
945
946	# default implementation for ->signal
947
948	our %SIG_CB;
949
950	sub signal {
951	my (undef, %arg) = @_;
952
953	my $signal = uc $arg{signal}
954	or Carp::croak "required option 'signal' is missing";
955
956	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
957	$SIG{$signal} ||= sub {
958	$_->() for values %{ $SIG_CB{$signal} || {} };
959	};	1755	};
		1756	die if $@;
960		1757
961	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1758	&signal
962	}
963
964	sub AnyEvent::Base::Signal::DESTROY {
965	my ($signal, $cb) = @{$_[0]};
966
967	delete $SIG_CB{$signal}{$cb};
968
969	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
970	}	1759	}
971		1760
972	# default implementation for ->child	1761	# default implementation for ->child
973		1762
974	our %PID_CB;	1763	our %PID_CB;
975	our $CHLD_W;	1764	our $CHLD_W;
976	our $CHLD_DELAY_W;	1765	our $CHLD_DELAY_W;
977	our $PID_IDLE;
978	our $WNOHANG;
979		1766
980	sub _child_wait {	1767	# used by many Impl's
981	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1768	sub _emit_childstatus($$) {
		1769	my (undef, $rpid, $rstatus) = @_;
		1770
		1771	$_->($rpid, $rstatus)
982	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1772	for values %{ $PID_CB{$rpid} || {} },
983	(values %{ $PID_CB{0} || {} });	1773	values %{ $PID_CB{0} || {} };
984	}
985
986	undef $PID_IDLE;
987	}
988
989	sub _sigchld {
990	# make sure we deliver these changes "synchronous" with the event loop.
991	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
992	undef $CHLD_DELAY_W;
993	&_child_wait;
994	});
995	}	1774	}
996		1775
997	sub child {	1776	sub child {
		1777	eval q{ # poor man's autoloading {}
		1778	*_sigchld = sub {
		1779	my $pid;
		1780
		1781	AnyEvent->_emit_childstatus ($pid, $?)
		1782	while ($pid = waitpid -1, WNOHANG) > 0;
		1783	};
		1784
		1785	*child = sub {
998	my (undef, %arg) = @_;	1786	my (undef, %arg) = @_;
999		1787
1000	defined (my $pid = $arg{pid} + 0)	1788	my $pid = $arg{pid};
1001	or Carp::croak "required option 'pid' is missing";	1789	my $cb = $arg{cb};
1002		1790
1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1791	$PID_CB{$pid}{$cb+0} = $cb;
1004		1792
1005	unless ($WNOHANG) {
1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1007	}
1008
1009	unless ($CHLD_W) {	1793	unless ($CHLD_W) {
1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1794	$CHLD_W = AE::signal CHLD => \&_sigchld;
1011	# child could be a zombie already, so make at least one round	1795	# child could be a zombie already, so make at least one round
1012	&_sigchld;	1796	&_sigchld;
1013	}	1797	}
1014		1798
1015	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1799	bless [$pid, $cb+0], "AnyEvent::Base::child"
1016	}	1800	};
1017		1801
1018	sub AnyEvent::Base::Child::DESTROY {	1802	*AnyEvent::Base::child::DESTROY = sub {
1019	my ($pid, $cb) = @{$_[0]};	1803	my ($pid, $icb) = @{$_[0]};
1020		1804
1021	delete $PID_CB{$pid}{$cb};	1805	delete $PID_CB{$pid}{$icb};
1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1806	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1023		1807
1024	undef $CHLD_W unless keys %PID_CB;	1808	undef $CHLD_W unless keys %PID_CB;
		1809	};
		1810	};
		1811	die if $@;
		1812
		1813	&child
		1814	}
		1815
		1816	# idle emulation is done by simply using a timer, regardless
		1817	# of whether the process is idle or not, and not letting
		1818	# the callback use more than 50% of the time.
		1819	sub idle {
		1820	eval q{ # poor man's autoloading {}
		1821	*idle = sub {
		1822	my (undef, %arg) = @_;
		1823
		1824	my ($cb, $w, $rcb) = $arg{cb};
		1825
		1826	$rcb = sub {
		1827	if ($cb) {
		1828	$w = AE::time;
		1829	&$cb;
		1830	$w = AE::time - $w;
		1831
		1832	# never use more then 50% of the time for the idle watcher,
		1833	# within some limits
		1834	$w = 0.0001 if $w < 0.0001;
		1835	$w = 5 if $w > 5;
		1836
		1837	$w = AE::timer $w, 0, $rcb;
		1838	} else {
		1839	# clean up...
		1840	undef $w;
		1841	undef $rcb;
		1842	}
		1843	};
		1844
		1845	$w = AE::timer 0.05, 0, $rcb;
		1846
		1847	bless \\$cb, "AnyEvent::Base::idle"
		1848	};
		1849
		1850	*AnyEvent::Base::idle::DESTROY = sub {
		1851	undef $${$_[0]};
		1852	};
		1853	};
		1854	die if $@;
		1855
		1856	&idle
1025	}	1857	}
1026		1858
1027	package AnyEvent::CondVar;	1859	package AnyEvent::CondVar;
1028		1860
1029	our @ISA = AnyEvent::CondVar::Base::;	1861	our @ISA = AnyEvent::CondVar::Base::;
1030		1862
		1863	# only to be used for subclassing
		1864	sub new {
		1865	my $class = shift;
		1866	bless AnyEvent->condvar (@_), $class
		1867	}
		1868
1031	package AnyEvent::CondVar::Base;	1869	package AnyEvent::CondVar::Base;
1032		1870
1033	use overload	1871	#use overload
1034	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1872	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1035	fallback => 1;	1873	# fallback => 1;
		1874
		1875	# save 300+ kilobytes by dirtily hardcoding overloading
		1876	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1877	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1878	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1879	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1880
		1881	our $WAITING;
1036		1882
1037	sub _send {	1883	sub _send {
1038	# nop	1884	# nop
		1885	}
		1886
		1887	sub _wait {
		1888	AnyEvent->_poll until $_[0]{_ae_sent};
1039	}	1889	}
1040		1890
1041	sub send {	1891	sub send {
1042	my $cv = shift;	1892	my $cv = shift;
1043	$cv->{_ae_sent} = [@_];	1893	$cv->{_ae_sent} = [@_];
…		…
1052		1902
1053	sub ready {	1903	sub ready {
1054	$_[0]{_ae_sent}	1904	$_[0]{_ae_sent}
1055	}	1905	}
1056		1906
1057	sub _wait {
1058	AnyEvent->one_event while !$_[0]{_ae_sent};
1059	}
1060
1061	sub recv {	1907	sub recv {
		1908	unless ($_[0]{_ae_sent}) {
		1909	$WAITING
		1910	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1911
		1912	local $WAITING = 1;
1062	$_[0]->_wait;	1913	$_[0]->_wait;
		1914	}
1063		1915
1064	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1916	$_[0]{_ae_croak}
1065	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1917	and Carp::croak $_[0]{_ae_croak};
		1918
		1919	wantarray
		1920	? @{ $_[0]{_ae_sent} }
		1921	: $_[0]{_ae_sent}[0]
1066	}	1922	}
1067		1923
1068	sub cb {	1924	sub cb {
1069	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1925	my $cv = shift;
		1926
		1927	@_
		1928	and $cv->{_ae_cb} = shift
		1929	and $cv->{_ae_sent}
		1930	and (delete $cv->{_ae_cb})->($cv);
		1931
1070	$_[0]{_ae_cb}	1932	$cv->{_ae_cb}
1071	}	1933	}
1072		1934
1073	sub begin {	1935	sub begin {
1074	++$_[0]{_ae_counter};	1936	++$_[0]{_ae_counter};
1075	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1937	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1080	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1942	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1081	}	1943	}
1082		1944
1083	# undocumented/compatibility with pre-3.4	1945	# undocumented/compatibility with pre-3.4
1084	*broadcast = \&send;	1946	*broadcast = \&send;
1085	*wait = \&_wait;	1947	*wait = \&recv;
		1948
		1949	=head1 ERROR AND EXCEPTION HANDLING
		1950
		1951	In general, AnyEvent does not do any error handling - it relies on the
		1952	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1953	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1954	checking of all AnyEvent methods, however, which is highly useful during
		1955	development.
		1956
		1957	As for exception handling (i.e. runtime errors and exceptions thrown while
		1958	executing a callback), this is not only highly event-loop specific, but
		1959	also not in any way wrapped by this module, as this is the job of the main
		1960	program.
		1961
		1962	The pure perl event loop simply re-throws the exception (usually
		1963	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1964	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1965	so on.
		1966
		1967	=head1 ENVIRONMENT VARIABLES
		1968
		1969	The following environment variables are used by this module or its
		1970	submodules.
		1971
		1972	Note that AnyEvent will remove I<all> environment variables starting with
		1973	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1974	enabled.
		1975
		1976	=over 4
		1977
		1978	=item C<PERL_ANYEVENT_VERBOSE>
		1979
		1980	By default, AnyEvent will be completely silent except in fatal
		1981	conditions. You can set this environment variable to make AnyEvent more
		1982	talkative.
		1983
		1984	When set to C<5> or higher, causes AnyEvent to warn about unexpected
		1985	conditions, such as not being able to load the event model specified by
		1986	C<PERL_ANYEVENT_MODEL>.
		1987
		1988	When set to C<7> or higher, cause AnyEvent to report to STDERR which event
		1989	model it chooses.
		1990
		1991	When set to C<8> or higher, then AnyEvent will report extra information on
		1992	which optional modules it loads and how it implements certain features.
		1993
		1994	=item C<PERL_ANYEVENT_STRICT>
		1995
		1996	AnyEvent does not do much argument checking by default, as thorough
		1997	argument checking is very costly. Setting this variable to a true value
		1998	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1999	check the arguments passed to most method calls. If it finds any problems,
		2000	it will croak.
		2001
		2002	In other words, enables "strict" mode.
		2003
		2004	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2005	>>, it is definitely recommended to keep it off in production. Keeping
		2006	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2007	can be very useful, however.
		2008
		2009	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2010
		2011	If this env variable is set, then its contents will be interpreted by
		2012	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		2013	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		2014	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		2015
		2016	This takes place when the first watcher is created.
		2017
		2018	For example, to bind a debug shell on a unix domain socket in
		2019	F<< /tmp/debug<pid>.sock >>, you could use this:
		2020
		2021	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2022
		2023	Note that creating sockets in F</tmp> is very unsafe on multiuser
		2024	systems.
		2025
		2026	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2027
		2028	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2029	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2030
		2031	=item C<PERL_ANYEVENT_MODEL>
		2032
		2033	This can be used to specify the event model to be used by AnyEvent, before
		2034	auto detection and -probing kicks in.
		2035
		2036	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2037	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2038	resulting module name is loaded and - if the load was successful - used as
		2039	event model backend. If it fails to load then AnyEvent will proceed with
		2040	auto detection and -probing.
		2041
		2042	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2043	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2044	the end of a string designates a module name and quotes it appropriately).
		2045
		2046	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2047	could start your program like this:
		2048
		2049	PERL_ANYEVENT_MODEL=Perl perl ...
		2050
		2051	=item C<PERL_ANYEVENT_PROTOCOLS>
		2052
		2053	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2054	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2055	of auto probing).
		2056
		2057	Must be set to a comma-separated list of protocols or address families,
		2058	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2059	used, and preference will be given to protocols mentioned earlier in the
		2060	list.
		2061
		2062	This variable can effectively be used for denial-of-service attacks
		2063	against local programs (e.g. when setuid), although the impact is likely
		2064	small, as the program has to handle conenction and other failures anyways.
		2065
		2066	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2067	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2068	- only support IPv4, never try to resolve or contact IPv6
		2069	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2070	IPv6, but prefer IPv6 over IPv4.
		2071
		2072	=item C<PERL_ANYEVENT_EDNS0>
		2073
		2074	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		2075	for DNS. This extension is generally useful to reduce DNS traffic, but
		2076	some (broken) firewalls drop such DNS packets, which is why it is off by
		2077	default.
		2078
		2079	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2080	EDNS0 in its DNS requests.
		2081
		2082	=item C<PERL_ANYEVENT_MAX_FORKS>
		2083
		2084	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2085	will create in parallel.
		2086
		2087	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2088
		2089	The default value for the C<max_outstanding> parameter for the default DNS
		2090	resolver - this is the maximum number of parallel DNS requests that are
		2091	sent to the DNS server.
		2092
		2093	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2094
		2095	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2096	configuration) in the default resolver. When set to the empty string, no
		2097	default config will be used.
		2098
		2099	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2100
		2101	When neither C<ca_file> nor C<ca_path> was specified during
		2102	L<AnyEvent::TLS> context creation, and either of these environment
		2103	variables exist, they will be used to specify CA certificate locations
		2104	instead of a system-dependent default.
		2105
		2106	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2107
		2108	When these are set to C<1>, then the respective modules are not
		2109	loaded. Mostly good for testing AnyEvent itself.
		2110
		2111	=back
1086		2112
1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2113	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1088		2114
1089	This is an advanced topic that you do not normally need to use AnyEvent in	2115	This is an advanced topic that you do not normally need to use AnyEvent in
1090	a module. This section is only of use to event loop authors who want to	2116	a module. This section is only of use to event loop authors who want to
…		…
1124		2150
1125	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2151	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1126	condition variables: code blocking while waiting for a condition will	2152	condition variables: code blocking while waiting for a condition will
1127	C<die>. This still works with most modules/usages, and blocking calls must	2153	C<die>. This still works with most modules/usages, and blocking calls must
1128	not be done in an interactive application, so it makes sense.	2154	not be done in an interactive application, so it makes sense.
1129
1130	=head1 ENVIRONMENT VARIABLES
1131
1132	The following environment variables are used by this module:
1133
1134	=over 4
1135
1136	=item C<PERL_ANYEVENT_VERBOSE>
1137
1138	By default, AnyEvent will be completely silent except in fatal
1139	conditions. You can set this environment variable to make AnyEvent more
1140	talkative.
1141
1142	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1143	conditions, such as not being able to load the event model specified by
1144	C<PERL_ANYEVENT_MODEL>.
1145
1146	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1147	model it chooses.
1148
1149	=item C<PERL_ANYEVENT_MODEL>
1150
1151	This can be used to specify the event model to be used by AnyEvent, before
1152	auto detection and -probing kicks in. It must be a string consisting
1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1154	and the resulting module name is loaded and if the load was successful,
1155	used as event model. If it fails to load AnyEvent will proceed with
1156	auto detection and -probing.
1157
1158	This functionality might change in future versions.
1159
1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1161	could start your program like this:
1162
1163	PERL_ANYEVENT_MODEL=Perl perl ...
1164
1165	=item C<PERL_ANYEVENT_PROTOCOLS>
1166
1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1169	of auto probing).
1170
1171	Must be set to a comma-separated list of protocols or address families,
1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1173	used, and preference will be given to protocols mentioned earlier in the
1174	list.
1175
1176	This variable can effectively be used for denial-of-service attacks
1177	against local programs (e.g. when setuid), although the impact is likely
1178	small, as the program has to handle connection errors already-
1179
1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1182	- only support IPv4, never try to resolve or contact IPv6
1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1184	IPv6, but prefer IPv6 over IPv4.
1185
1186	=item C<PERL_ANYEVENT_EDNS0>
1187
1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic, but
1190	some (broken) firewalls drop such DNS packets, which is why it is off by
1191	default.
1192
1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1194	EDNS0 in its DNS requests.
1195
1196	=item C<PERL_ANYEVENT_MAX_FORKS>
1197
1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1199	will create in parallel.
1200
1201	=back
1202		2155
1203	=head1 EXAMPLE PROGRAM	2156	=head1 EXAMPLE PROGRAM
1204		2157
1205	The following program uses an I/O watcher to read data from STDIN, a timer	2158	The following program uses an I/O watcher to read data from STDIN, a timer
1206	to display a message once per second, and a condition variable to quit the	2159	to display a message once per second, and a condition variable to quit the
…		…
1219	warn "read: $input\n"; # output what has been read	2172	warn "read: $input\n"; # output what has been read
1220	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2173	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1221	},	2174	},
1222	);	2175	);
1223		2176
1224	my $time_watcher; # can only be used once
1225
1226	sub new_timer {
1227	$timer = AnyEvent->timer (after => 1, cb => sub {	2177	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1228	warn "timeout\n"; # print 'timeout' about every second	2178	warn "timeout\n"; # print 'timeout' at most every second
1229	&new_timer; # and restart the time
1230	});	2179	});
1231	}
1232
1233	new_timer; # create first timer
1234		2180
1235	$cv->recv; # wait until user enters /^q/i	2181	$cv->recv; # wait until user enters /^q/i
1236		2182
1237	=head1 REAL-WORLD EXAMPLE	2183	=head1 REAL-WORLD EXAMPLE
1238		2184
…		…
1311		2257
1312	The actual code goes further and collects all errors (C<die>s, exceptions)	2258	The actual code goes further and collects all errors (C<die>s, exceptions)
1313	that occurred during request processing. The C<result> method detects	2259	that occurred during request processing. The C<result> method detects
1314	whether an exception as thrown (it is stored inside the $txn object)	2260	whether an exception as thrown (it is stored inside the $txn object)
1315	and just throws the exception, which means connection errors and other	2261	and just throws the exception, which means connection errors and other
1316	problems get reported tot he code that tries to use the result, not in a	2262	problems get reported to the code that tries to use the result, not in a
1317	random callback.	2263	random callback.
1318		2264
1319	All of this enables the following usage styles:	2265	All of this enables the following usage styles:
1320		2266
1321	1. Blocking:	2267	1. Blocking:
…		…
1369	through AnyEvent. The benchmark creates a lot of timers (with a zero	2315	through AnyEvent. The benchmark creates a lot of timers (with a zero
1370	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2316	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1371	which it is), lets them fire exactly once and destroys them again.	2317	which it is), lets them fire exactly once and destroys them again.
1372		2318
1373	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2319	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1374	distribution.	2320	distribution. It uses the L<AE> interface, which makes a real difference
		2321	for the EV and Perl backends only.
1375		2322
1376	=head3 Explanation of the columns	2323	=head3 Explanation of the columns
1377		2324
1378	I<watcher> is the number of event watchers created/destroyed. Since	2325	I<watcher> is the number of event watchers created/destroyed. Since
1379	different event models feature vastly different performances, each event	2326	different event models feature vastly different performances, each event
…		…
1400	watcher.	2347	watcher.
1401		2348
1402	=head3 Results	2349	=head3 Results
1403		2350
1404	name watchers bytes create invoke destroy comment	2351	name watchers bytes create invoke destroy comment
1405	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2352	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1406	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2353	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1407	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2354	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1408	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2355	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1409	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2356	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1410	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2357	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2358	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2359	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1411	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2360	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1412	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2361	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1413	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2362	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1414	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2363	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1415		2364
1416	=head3 Discussion	2365	=head3 Discussion
1417		2366
1418	The benchmark does I<not> measure scalability of the event loop very	2367	The benchmark does I<not> measure scalability of the event loop very
1419	well. For example, a select-based event loop (such as the pure perl one)	2368	well. For example, a select-based event loop (such as the pure perl one)
…		…
1431	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2380	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1432	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2381	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1433	cycles with POE.	2382	cycles with POE.
1434		2383
1435	C<EV> is the sole leader regarding speed and memory use, which are both	2384	C<EV> is the sole leader regarding speed and memory use, which are both
1436	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2385	maximal/minimal, respectively. When using the L<AE> API there is zero
		2386	overhead (when going through the AnyEvent API create is about 5-6 times
		2387	slower, with other times being equal, so still uses far less memory than
1437	far less memory than any other event loop and is still faster than Event	2388	any other event loop and is still faster than Event natively).
1438	natively.
1439		2389
1440	The pure perl implementation is hit in a few sweet spots (both the	2390	The pure perl implementation is hit in a few sweet spots (both the
1441	constant timeout and the use of a single fd hit optimisations in the perl	2391	constant timeout and the use of a single fd hit optimisations in the perl
1442	interpreter and the backend itself). Nevertheless this shows that it	2392	interpreter and the backend itself). Nevertheless this shows that it
1443	adds very little overhead in itself. Like any select-based backend its	2393	adds very little overhead in itself. Like any select-based backend its
1444	performance becomes really bad with lots of file descriptors (and few of	2394	performance becomes really bad with lots of file descriptors (and few of
1445	them active), of course, but this was not subject of this benchmark.	2395	them active), of course, but this was not subject of this benchmark.
1446		2396
1447	The C<Event> module has a relatively high setup and callback invocation	2397	The C<Event> module has a relatively high setup and callback invocation
1448	cost, but overall scores in on the third place.	2398	cost, but overall scores in on the third place.
		2399
		2400	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2401	when using its pure perl backend.
1449		2402
1450	C<Glib>'s memory usage is quite a bit higher, but it features a	2403	C<Glib>'s memory usage is quite a bit higher, but it features a
1451	faster callback invocation and overall ends up in the same class as	2404	faster callback invocation and overall ends up in the same class as
1452	C<Event>. However, Glib scales extremely badly, doubling the number of	2405	C<Event>. However, Glib scales extremely badly, doubling the number of
1453	watchers increases the processing time by more than a factor of four,	2406	watchers increases the processing time by more than a factor of four,
…		…
1488	(even when used without AnyEvent), but most event loops have acceptable	2441	(even when used without AnyEvent), but most event loops have acceptable
1489	performance with or without AnyEvent.	2442	performance with or without AnyEvent.
1490		2443
1491	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2444	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1492	the actual event loop, only with extremely fast event loops such as EV	2445	the actual event loop, only with extremely fast event loops such as EV
1493	adds AnyEvent significant overhead.	2446	does AnyEvent add significant overhead.
1494		2447
1495	=item * You should avoid POE like the plague if you want performance or	2448	=item * You should avoid POE like the plague if you want performance or
1496	reasonable memory usage.	2449	reasonable memory usage.
1497		2450
1498	=back	2451	=back
…		…
1514	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2467	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1515	(1%) are active. This mirrors the activity of large servers with many	2468	(1%) are active. This mirrors the activity of large servers with many
1516	connections, most of which are idle at any one point in time.	2469	connections, most of which are idle at any one point in time.
1517		2470
1518	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2471	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1519	distribution.	2472	distribution. It uses the L<AE> interface, which makes a real difference
		2473	for the EV and Perl backends only.
1520		2474
1521	=head3 Explanation of the columns	2475	=head3 Explanation of the columns
1522		2476
1523	I<sockets> is the number of sockets, and twice the number of "servers" (as	2477	I<sockets> is the number of sockets, and twice the number of "servers" (as
1524	each server has a read and write socket end).	2478	each server has a read and write socket end).
…		…
1531	it to another server. This includes deleting the old timeout and creating	2485	it to another server. This includes deleting the old timeout and creating
1532	a new one that moves the timeout into the future.	2486	a new one that moves the timeout into the future.
1533		2487
1534	=head3 Results	2488	=head3 Results
1535		2489
1536	name sockets create request	2490	name sockets create request
1537	EV 20000 69.01 11.16	2491	EV 20000 62.66 7.99
1538	Perl 20000 73.32 35.87	2492	Perl 20000 68.32 32.64
1539	Event 20000 212.62 257.32	2493	IOAsync 20000 174.06 101.15 epoll
1540	Glib 20000 651.16 1896.30	2494	IOAsync 20000 174.67 610.84 poll
		2495	Event 20000 202.69 242.91
		2496	Glib 20000 557.01 1689.52
1541	POE 20000 349.67 12317.24 uses POE::Loop::Event	2497	POE 20000 341.54 12086.32 uses POE::Loop::Event
1542		2498
1543	=head3 Discussion	2499	=head3 Discussion
1544		2500
1545	This benchmark I<does> measure scalability and overall performance of the	2501	This benchmark I<does> measure scalability and overall performance of the
1546	particular event loop.	2502	particular event loop.
…		…
1548	EV is again fastest. Since it is using epoll on my system, the setup time	2504	EV is again fastest. Since it is using epoll on my system, the setup time
1549	is relatively high, though.	2505	is relatively high, though.
1550		2506
1551	Perl surprisingly comes second. It is much faster than the C-based event	2507	Perl surprisingly comes second. It is much faster than the C-based event
1552	loops Event and Glib.	2508	loops Event and Glib.
		2509
		2510	IO::Async performs very well when using its epoll backend, and still quite
		2511	good compared to Glib when using its pure perl backend.
1553		2512
1554	Event suffers from high setup time as well (look at its code and you will	2513	Event suffers from high setup time as well (look at its code and you will
1555	understand why). Callback invocation also has a high overhead compared to	2514	understand why). Callback invocation also has a high overhead compared to
1556	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2515	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1557	uses select or poll in basically all documented configurations.	2516	uses select or poll in basically all documented configurations.
…		…
1620	=item * C-based event loops perform very well with small number of	2579	=item * C-based event loops perform very well with small number of
1621	watchers, as the management overhead dominates.	2580	watchers, as the management overhead dominates.
1622		2581
1623	=back	2582	=back
1624		2583
		2584	=head2 THE IO::Lambda BENCHMARK
		2585
		2586	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2587	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2588	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2589	shouldn't come as a surprise to anybody). As such, the benchmark is
		2590	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2591	very optimal. But how would AnyEvent compare when used without the extra
		2592	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2593
		2594	The benchmark itself creates an echo-server, and then, for 500 times,
		2595	connects to the echo server, sends a line, waits for the reply, and then
		2596	creates the next connection. This is a rather bad benchmark, as it doesn't
		2597	test the efficiency of the framework or much non-blocking I/O, but it is a
		2598	benchmark nevertheless.
		2599
		2600	name runtime
		2601	Lambda/select 0.330 sec
		2602	+ optimized 0.122 sec
		2603	Lambda/AnyEvent 0.327 sec
		2604	+ optimized 0.138 sec
		2605	Raw sockets/select 0.077 sec
		2606	POE/select, components 0.662 sec
		2607	POE/select, raw sockets 0.226 sec
		2608	POE/select, optimized 0.404 sec
		2609
		2610	AnyEvent/select/nb 0.085 sec
		2611	AnyEvent/EV/nb 0.068 sec
		2612	+state machine 0.134 sec
		2613
		2614	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2615	benchmarks actually make blocking connects and use 100% blocking I/O,
		2616	defeating the purpose of an event-based solution. All of the newly
		2617	written AnyEvent benchmarks use 100% non-blocking connects (using
		2618	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2619	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2620	generally require a lot more bookkeeping and event handling than blocking
		2621	connects (which involve a single syscall only).
		2622
		2623	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2624	offers similar expressive power as POE and IO::Lambda, using conventional
		2625	Perl syntax. This means that both the echo server and the client are 100%
		2626	non-blocking, further placing it at a disadvantage.
		2627
		2628	As you can see, the AnyEvent + EV combination even beats the
		2629	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2630	backend easily beats IO::Lambda and POE.
		2631
		2632	And even the 100% non-blocking version written using the high-level (and
		2633	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2634	higher level ("unoptimised") abstractions by a large margin, even though
		2635	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2636
		2637	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2638	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2639	part of the IO::Lambda distribution and were used without any changes.
		2640
		2641
		2642	=head1 SIGNALS
		2643
		2644	AnyEvent currently installs handlers for these signals:
		2645
		2646	=over 4
		2647
		2648	=item SIGCHLD
		2649
		2650	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2651	emulation for event loops that do not support them natively. Also, some
		2652	event loops install a similar handler.
		2653
		2654	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2655	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2656
		2657	=item SIGPIPE
		2658
		2659	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2660	when AnyEvent gets loaded.
		2661
		2662	The rationale for this is that AnyEvent users usually do not really depend
		2663	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2664	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2665	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2666	some random socket.
		2667
		2668	The rationale for installing a no-op handler as opposed to ignoring it is
		2669	that this way, the handler will be restored to defaults on exec.
		2670
		2671	Feel free to install your own handler, or reset it to defaults.
		2672
		2673	=back
		2674
		2675	=cut
		2676
		2677	undef $SIG{CHLD}
		2678	if $SIG{CHLD} eq 'IGNORE';
		2679
		2680	$SIG{PIPE} = sub { }
		2681	unless defined $SIG{PIPE};
		2682
		2683	=head1 RECOMMENDED/OPTIONAL MODULES
		2684
		2685	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2686	its built-in modules) are required to use it.
		2687
		2688	That does not mean that AnyEvent won't take advantage of some additional
		2689	modules if they are installed.
		2690
		2691	This section explains which additional modules will be used, and how they
		2692	affect AnyEvent's operation.
		2693
		2694	=over 4
		2695
		2696	=item L<Async::Interrupt>
		2697
		2698	This slightly arcane module is used to implement fast signal handling: To
		2699	my knowledge, there is no way to do completely race-free and quick
		2700	signal handling in pure perl. To ensure that signals still get
		2701	delivered, AnyEvent will start an interval timer to wake up perl (and
		2702	catch the signals) with some delay (default is 10 seconds, look for
		2703	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2704
		2705	If this module is available, then it will be used to implement signal
		2706	catching, which means that signals will not be delayed, and the event loop
		2707	will not be interrupted regularly, which is more efficient (and good for
		2708	battery life on laptops).
		2709
		2710	This affects not just the pure-perl event loop, but also other event loops
		2711	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2712
		2713	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2714	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2715	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2716	does nothing for those backends.
		2717
		2718	=item L<EV>
		2719
		2720	This module isn't really "optional", as it is simply one of the backend
		2721	event loops that AnyEvent can use. However, it is simply the best event
		2722	loop available in terms of features, speed and stability: It supports
		2723	the AnyEvent API optimally, implements all the watcher types in XS, does
		2724	automatic timer adjustments even when no monotonic clock is available,
		2725	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2726	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2727	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2728
		2729	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2730	then this module will do nothing for you.
		2731
		2732	=item L<Guard>
		2733
		2734	The guard module, when used, will be used to implement
		2735	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2736	lot less memory), but otherwise doesn't affect guard operation much. It is
		2737	purely used for performance.
		2738
		2739	=item L<JSON> and L<JSON::XS>
		2740
		2741	One of these modules is required when you want to read or write JSON data
		2742	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2743	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2744
		2745	=item L<Net::SSLeay>
		2746
		2747	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2748	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2749	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2750
		2751	=item L<Time::HiRes>
		2752
		2753	This module is part of perl since release 5.008. It will be used when the
		2754	chosen event library does not come with a timing source of its own. The
		2755	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2756	try to use a monotonic clock for timing stability.
		2757
		2758	=back
		2759
1625		2760
1626	=head1 FORK	2761	=head1 FORK
1627		2762
1628	Most event libraries are not fork-safe. The ones who are usually are	2763	Most event libraries are not fork-safe. The ones who are usually are
1629	because they rely on inefficient but fork-safe C<select> or C<poll>	2764	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1630	calls. Only L<EV> is fully fork-aware.	2765	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2766	are usually badly thought-out hacks that are incompatible with fork in
		2767	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2768	continue event-processing in both parent and child (or both, if you know
		2769	what you are doing).
		2770
		2771	This means that, in general, you cannot fork and do event processing in
		2772	the child if the event library was initialised before the fork (which
		2773	usually happens when the first AnyEvent watcher is created, or the library
		2774	is loaded).
1631		2775
1632	If you have to fork, you must either do so I<before> creating your first	2776	If you have to fork, you must either do so I<before> creating your first
1633	watcher OR you must not use AnyEvent at all in the child.	2777	watcher OR you must not use AnyEvent at all in the child OR you must do
		2778	something completely out of the scope of AnyEvent.
		2779
		2780	The problem of doing event processing in the parent I<and> the child
		2781	is much more complicated: even for backends that I<are> fork-aware or
		2782	fork-safe, their behaviour is not usually what you want: fork clones all
		2783	watchers, that means all timers, I/O watchers etc. are active in both
		2784	parent and child, which is almost never what you want. USing C<exec>
		2785	to start worker children from some kind of manage rprocess is usually
		2786	preferred, because it is much easier and cleaner, at the expense of having
		2787	to have another binary.
1634		2788
1635		2789
1636	=head1 SECURITY CONSIDERATIONS	2790	=head1 SECURITY CONSIDERATIONS
1637		2791
1638	AnyEvent can be forced to load any event model via	2792	AnyEvent can be forced to load any event model via
…		…
1643	specified in the variable.	2797	specified in the variable.
1644		2798
1645	You can make AnyEvent completely ignore this variable by deleting it	2799	You can make AnyEvent completely ignore this variable by deleting it
1646	before the first watcher gets created, e.g. with a C<BEGIN> block:	2800	before the first watcher gets created, e.g. with a C<BEGIN> block:
1647		2801
1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2802	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1649		2803
1650	use AnyEvent;	2804	use AnyEvent;
1651		2805
1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2806	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1653	be used to probe what backend is used and gain other information (which is	2807	be used to probe what backend is used and gain other information (which is
1654	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2808	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2809	$ENV{PERL_ANYEVENT_STRICT}.
		2810
		2811	Note that AnyEvent will remove I<all> environment variables starting with
		2812	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2813	enabled.
		2814
		2815
		2816	=head1 BUGS
		2817
		2818	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2819	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2820	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2821	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2822	pronounced).
1655		2823
1656		2824
1657	=head1 SEE ALSO	2825	=head1 SEE ALSO
1658		2826
1659	Utility functions: L<AnyEvent::Util>.	2827	Tutorial/Introduction: L<AnyEvent::Intro>.
1660		2828
1661	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2829	FAQ: L<AnyEvent::FAQ>.
1662	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2830
		2831	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2832	(simply logging).
		2833
		2834	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2835	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2836
		2837	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2838	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2839	L<Qt>, L<POE>, L<FLTK>.
1663		2840
1664	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2841	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1665	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2842	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1666	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2843	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		2844	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1667	L<AnyEvent::Impl::POE>.	2845	L<AnyEvent::Impl::FLTK>.
1668		2846
1669	Non-blocking file handles, sockets, TCP clients and	2847	Non-blocking handles, pipes, stream sockets, TCP clients and
1670	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2848	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1671		2849
1672	Asynchronous DNS: L<AnyEvent::DNS>.	2850	Asynchronous DNS: L<AnyEvent::DNS>.
1673		2851
1674	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2852	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1675		2853
1676	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2854	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2855	L<AnyEvent::HTTP>.
1677		2856
1678		2857
1679	=head1 AUTHOR	2858	=head1 AUTHOR
1680		2859
1681	Marc Lehmann <schmorp@schmorp.de>	2860	Marc Lehmann <schmorp@schmorp.de>
1682	http://home.schmorp.de/	2861	http://home.schmorp.de/
1683		2862
1684	=cut	2863	=cut
1685		2864
1686	1	2865	1
1687		2866

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