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Revision 1.144 by root, Thu May 29 00:14:35 2008 UTC vs.
Revision 1.398 by root, Tue Mar 27 16:21:11 2012 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	FLTK 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.
…		…
258	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
259	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
260		320
261	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
262	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
263	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
264		324
265	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
266	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
267		327
268	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>
269	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
270		330
271	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
272	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
273	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
274	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
275	after three seconds.	335	after three seconds.
276		336
…		…
294	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
295	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
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	357	account.
298		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
299	=back	381	=back
300		382
301	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
302		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
303	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
304	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
305	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
306		390
307	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
310		394
…		…
312	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
313	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,
314	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
315		399
316	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
317	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
318		403
319	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
320	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
321		407
322	Example: exit on SIGINT	408	Example: exit on SIGINT
323		409
324	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
325		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling)
		421	or "unsafe" (asynchronous) - the former might delay signal delivery
		422	indefinitely, the latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support
		432	attaching callbacks to signals in a generic way, which is a pity,
		433	as you cannot do race-free signal handling in perl, requiring
		434	C libraries for this. AnyEvent will try to do its best, which
		435	means in some cases, signals will be delayed. The maximum time
		436	a signal might be delayed is 10 seconds by default, but can
		437	be overriden via C<$ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY}> or
		438	C<$AnyEvent::MAX_SIGNAL_LATENCY> - see the L<ENVIRONMENT VARIABLES>
		439	section for details.
		440
		441	All these problems can be avoided by installing the optional
		442	L<Async::Interrupt> module, which works with most event loops. It will not
		443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		444	(and not with L<POE> currently). For those, you just have to suffer the
		445	delays.
		446
326	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
327		448
		449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		450
328	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
329		452
330	The child process is specified by the C<pid> argument (if set to C<0>, it	453	The child process is specified by the C<pid> argument (on some backends,
331	watches for any child process exit). The watcher will trigger as often	454	using C<0> watches for any child process exit, on others this will
332	as status change for the child are received. This works by installing a	455	croak). The watcher will be triggered only when the child process has
333	signal handler for C<SIGCHLD>. The callback will be called with the pid	456	finished and an exit status is available, not on any trace events
334	and exit status (as returned by waitpid), so unlike other watcher types,	457	(stopped/continued).
335	you I<can> rely on child watcher callback arguments.	458
		459	The callback will be called with the pid and exit status (as returned by
		460	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		461	callback arguments.
		462
		463	This watcher type works by installing a signal handler for C<SIGCHLD>,
		464	and since it cannot be shared, nothing else should use SIGCHLD or reap
		465	random child processes (waiting for specific child processes, e.g. inside
		466	C<system>, is just fine).
336		467
337	There is a slight catch to child watchers, however: you usually start them	468	There is a slight catch to child watchers, however: you usually start them
338	I<after> the child process was created, and this means the process could	469	I<after> the child process was created, and this means the process could
339	have exited already (and no SIGCHLD will be sent anymore).	470	have exited already (and no SIGCHLD will be sent anymore).
340		471
341	Not all event models handle this correctly (POE doesn't), but even for	472	Not all event models handle this correctly (neither POE nor IO::Async do,
		473	see their AnyEvent::Impl manpages for details), but even for event models
342	event models that I<do> handle this correctly, they usually need to be	474	that I<do> handle this correctly, they usually need to be loaded before
343	loaded before the process exits (i.e. before you fork in the first place).	475	the process exits (i.e. before you fork in the first place). AnyEvent's
		476	pure perl event loop handles all cases correctly regardless of when you
		477	start the watcher.
344		478
345	This means you cannot create a child watcher as the very first thing in an	479	This means you cannot create a child watcher as the very first
346	AnyEvent program, you I<have> to create at least one watcher before you	480	thing in an AnyEvent program, you I<have> to create at least one
347	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	481	watcher before you C<fork> the child (alternatively, you can call
		482	C<AnyEvent::detect>).
		483
		484	As most event loops do not support waiting for child events, they will be
		485	emulated by AnyEvent in most cases, in which case the latency and race
		486	problems mentioned in the description of signal watchers apply.
348		487
349	Example: fork a process and wait for it	488	Example: fork a process and wait for it
350		489
351	my $done = AnyEvent->condvar;	490	my $done = AnyEvent->condvar;
352		491
353	my $pid = fork or exit 5;	492	my $pid = fork or exit 5;
354		493
355	my $w = AnyEvent->child (	494	my $w = AnyEvent->child (
356	pid => $pid,	495	pid => $pid,
357	cb => sub {	496	cb => sub {
358	my ($pid, $status) = @_;	497	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	498	warn "pid $pid exited with status $status";
360	$done->send;	499	$done->send;
361	},	500	},
362	);	501	);
363		502
364	# do something else, then wait for process exit	503	# do something else, then wait for process exit
365	$done->recv;	504	$done->recv;
		505
		506	=head2 IDLE WATCHERS
		507
		508	$w = AnyEvent->idle (cb => <callback>);
		509
		510	This will repeatedly invoke the callback after the process becomes idle,
		511	until either the watcher is destroyed or new events have been detected.
		512
		513	Idle watchers are useful when there is a need to do something, but it
		514	is not so important (or wise) to do it instantly. The callback will be
		515	invoked only when there is "nothing better to do", which is usually
		516	defined as "all outstanding events have been handled and no new events
		517	have been detected". That means that idle watchers ideally get invoked
		518	when the event loop has just polled for new events but none have been
		519	detected. Instead of blocking to wait for more events, the idle watchers
		520	will be invoked.
		521
		522	Unfortunately, most event loops do not really support idle watchers (only
		523	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		524	will simply call the callback "from time to time".
		525
		526	Example: read lines from STDIN, but only process them when the
		527	program is otherwise idle:
		528
		529	my @lines; # read data
		530	my $idle_w;
		531	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		532	push @lines, scalar <STDIN>;
		533
		534	# start an idle watcher, if not already done
		535	$idle_w ||= AnyEvent->idle (cb => sub {
		536	# handle only one line, when there are lines left
		537	if (my $line = shift @lines) {
		538	print "handled when idle: $line";
		539	} else {
		540	# otherwise disable the idle watcher again
		541	undef $idle_w;
		542	}
		543	});
		544	});
366		545
367	=head2 CONDITION VARIABLES	546	=head2 CONDITION VARIABLES
		547
		548	$cv = AnyEvent->condvar;
		549
		550	$cv->send (<list>);
		551	my @res = $cv->recv;
368		552
369	If you are familiar with some event loops you will know that all of them	553	If you are familiar with some event loops you will know that all of them
370	require you to run some blocking "loop", "run" or similar function that	554	require you to run some blocking "loop", "run" or similar function that
371	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
372		556
373	AnyEvent is different, it expects somebody else to run the event loop and	557	AnyEvent is slightly different: it expects somebody else to run the event
374	will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
375		559
376	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
377	because they represent a condition that must become true.	561	they represent a condition that must become true.
		562
		563	Now is probably a good time to look at the examples further below.
378		564
379	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
381	C<cb>, which specifies a callback to be called when the condition variable	567	C<cb>, which specifies a callback to be called when the condition variable
382	becomes true.	568	becomes true, with the condition variable as the first argument (but not
		569	the results).
383		570
384	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
385	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
386	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	574	->send >> method).
388		575
389	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
390	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
391	in time where multiple outstanding events have been processed. And yet	578
392	another way to call them is transactions - each condition variable can be	579	=over 4
393	used to represent a transaction, which finishes at some point and delivers	580
394	a result.	581	=item * Condition variables are like callbacks - you can call them (and pass them instead
		582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
395		599
396	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
397	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
398	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
399	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
412		616
413	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
414	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
415	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
416	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
417	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
418		622
419	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
420	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
421	for the send to occur.	625	for the send to occur.
422		626
423	Example: wait for a timer.	627	Example: wait for a timer.
424		628
425	# wait till the result is ready	629	# condition: "wait till the timer is fired"
426	my $result_ready = AnyEvent->condvar;	630	my $timer_fired = AnyEvent->condvar;
427		631
428	# do something such as adding a timer	632	# create the timer - we could wait for, say
429	# or socket watcher the calls $result_ready->send	633	# a handle becomign ready, or even an
430	# when the "result" is ready.	634	# AnyEvent::HTTP request to finish, but
431	# in this case, we simply use a timer:	635	# in this case, we simply use a timer:
432	my $w = AnyEvent->timer (	636	my $w = AnyEvent->timer (
433	after => 1,	637	after => 1,
434	cb => sub { $result_ready->send },	638	cb => sub { $timer_fired->send },
435	);	639	);
436		640
437	# this "blocks" (while handling events) till the callback	641	# this "blocks" (while handling events) till the callback
438	# calls send	642	# calls ->send
439	$result_ready->recv;	643	$timer_fired->recv;
440		644
441	Example: wait for a timer, but take advantage of the fact that	645	Example: wait for a timer, but take advantage of the fact that condition
442	condition variables are also code references.	646	variables are also callable directly.
443		647
444	my $done = AnyEvent->condvar;	648	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	649	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$done->recv;	650	$done->recv;
		651
		652	Example: Imagine an API that returns a condvar and doesn't support
		653	callbacks. This is how you make a synchronous call, for example from
		654	the main program:
		655
		656	use AnyEvent::CouchDB;
		657
		658	...
		659
		660	my @info = $couchdb->info->recv;
		661
		662	And this is how you would just set a callback to be called whenever the
		663	results are available:
		664
		665	$couchdb->info->cb (sub {
		666	my @info = $_[0]->recv;
		667	});
447		668
448	=head3 METHODS FOR PRODUCERS	669	=head3 METHODS FOR PRODUCERS
449		670
450	These methods should only be used by the producing side, i.e. the	671	These methods should only be used by the producing side, i.e. the
451	code/module that eventually sends the signal. Note that it is also	672	code/module that eventually sends the signal. Note that it is also
…		…
464	immediately from within send.	685	immediately from within send.
465		686
466	Any arguments passed to the C<send> call will be returned by all	687	Any arguments passed to the C<send> call will be returned by all
467	future C<< ->recv >> calls.	688	future C<< ->recv >> calls.
468		689
469	Condition variables are overloaded so one can call them directly	690	Condition variables are overloaded so one can call them directly (as if
470	(as a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
471	C<send>. Note, however, that many C-based event loops do not handle	692	C<send>.
472	overloading, so as tempting as it may be, passing a condition variable
473	instead of a callback does not work. Both the pure perl and EV loops
474	support overloading, however, as well as all functions that use perl to
475	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
476	example).
477		693
478	=item $cv->croak ($error)	694	=item $cv->croak ($error)
479		695
480	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
481	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
482		698
483	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
484	user/consumer.	700	user/consumer. Doing it this way instead of calling C<croak> directly
		701	delays the error detection, but has the overwhelming advantage that it
		702	diagnoses the error at the place where the result is expected, and not
		703	deep in some event callback with no connection to the actual code causing
		704	the problem.
485		705
486	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
487		707
488	=item $cv->end	708	=item $cv->end
489
490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
491		709
492	These two methods can be used to combine many transactions/events into	710	These two methods can be used to combine many transactions/events into
493	one. For example, a function that pings many hosts in parallel might want	711	one. For example, a function that pings many hosts in parallel might want
494	to use a condition variable for the whole process.	712	to use a condition variable for the whole process.
495		713
496	Every call to C<< ->begin >> will increment a counter, and every call to	714	Every call to C<< ->begin >> will increment a counter, and every call to
497	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	715	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
498	>>, the (last) callback passed to C<begin> will be executed. That callback	716	>>, the (last) callback passed to C<begin> will be executed, passing the
499	is I<supposed> to call C<< ->send >>, but that is not required. If no	717	condvar as first argument. That callback is I<supposed> to call C<< ->send
500	callback was set, C<send> will be called without any arguments.	718	>>, but that is not required. If no group callback was set, C<send> will
		719	be called without any arguments.
501		720
502	Let's clarify this with the ping example:	721	You can think of C<< $cv->send >> giving you an OR condition (one call
		722	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		723	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		724
		725	Let's start with a simple example: you have two I/O watchers (for example,
		726	STDOUT and STDERR for a program), and you want to wait for both streams to
		727	close before activating a condvar:
503		728
504	my $cv = AnyEvent->condvar;	729	my $cv = AnyEvent->condvar;
505		730
		731	$cv->begin; # first watcher
		732	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		733	defined sysread $fh1, my $buf, 4096
		734	or $cv->end;
		735	});
		736
		737	$cv->begin; # second watcher
		738	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		739	defined sysread $fh2, my $buf, 4096
		740	or $cv->end;
		741	});
		742
		743	$cv->recv;
		744
		745	This works because for every event source (EOF on file handle), there is
		746	one call to C<begin>, so the condvar waits for all calls to C<end> before
		747	sending.
		748
		749	The ping example mentioned above is slightly more complicated, as the
		750	there are results to be passwd back, and the number of tasks that are
		751	begun can potentially be zero:
		752
		753	my $cv = AnyEvent->condvar;
		754
506	my %result;	755	my %result;
507	$cv->begin (sub { $cv->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
508		757
509	for my $host (@list_of_hosts) {	758	for my $host (@list_of_hosts) {
510	$cv->begin;	759	$cv->begin;
511	ping_host_then_call_callback $host, sub {	760	ping_host_then_call_callback $host, sub {
512	$result{$host} = ...;	761	$result{$host} = ...;
…		…
527	loop, which serves two important purposes: first, it sets the callback	776	loop, which serves two important purposes: first, it sets the callback
528	to be called once the counter reaches C<0>, and second, it ensures that	777	to be called once the counter reaches C<0>, and second, it ensures that
529	C<send> is called even when C<no> hosts are being pinged (the loop	778	C<send> is called even when C<no> hosts are being pinged (the loop
530	doesn't execute once).	779	doesn't execute once).
531		780
532	This is the general pattern when you "fan out" into multiple subrequests:	781	This is the general pattern when you "fan out" into multiple (but
533	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
534	is called at least once, and then, for each subrequest you start, call	783	the callback and ensure C<end> is called at least once, and then, for each
535	C<begin> and for each subrequest you finish, call C<end>.	784	subrequest you start, call C<begin> and for each subrequest you finish,
		785	call C<end>.
536		786
537	=back	787	=back
538		788
539	=head3 METHODS FOR CONSUMERS	789	=head3 METHODS FOR CONSUMERS
540		790
…		…
544	=over 4	794	=over 4
545		795
546	=item $cv->recv	796	=item $cv->recv
547		797
548	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
549	>> methods have been called on c<$cv>, while servicing other watchers	799	>> methods have been called on C<$cv>, while servicing other watchers
550	normally.	800	normally.
551		801
552	You can only wait once on a condition - additional calls are valid but	802	You can only wait once on a condition - additional calls are valid but
553	will return immediately.	803	will return immediately.
554		804
…		…
556	function will call C<croak>.	806	function will call C<croak>.
557		807
558	In list context, all parameters passed to C<send> will be returned,	808	In list context, all parameters passed to C<send> will be returned,
559	in scalar context only the first one will be returned.	809	in scalar context only the first one will be returned.
560		810
		811	Note that doing a blocking wait in a callback is not supported by any
		812	event loop, that is, recursive invocation of a blocking C<< ->recv
		813	>> is not allowed, and the C<recv> call will C<croak> if such a
		814	condition is detected. This condition can be slightly loosened by using
		815	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		816	any thread that doesn't run the event loop itself.
		817
561	Not all event models support a blocking wait - some die in that case	818	Not all event models support a blocking wait - some die in that case
562	(programs might want to do that to stay interactive), so I<if you are	819	(programs might want to do that to stay interactive), so I<if you are
563	using this from a module, never require a blocking wait>, but let the	820	using this from a module, never require a blocking wait>. Instead, let the
564	caller decide whether the call will block or not (for example, by coupling	821	caller decide whether the call will block or not (for example, by coupling
565	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
566	callbacks so the caller knows that getting the result will not block,	823	callbacks so the caller knows that getting the result will not block,
567	while still supporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
568		825
569	Another reason I<never> to C<< ->recv >> in a module is that you cannot
570	sensibly have two C<< ->recv >>'s in parallel, as that would require
571	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
572	can supply.
573
574	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
575	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
576	versions and also integrates coroutines into AnyEvent, making blocking
577	C<< ->recv >> calls perfectly safe as long as they are done from another
578	coroutine (one that doesn't run the event loop).
579
580	You can ensure that C<< -recv >> never blocks by setting a callback and	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
581	only calling C<< ->recv >> from within that callback (or at a later	827	only calling C<< ->recv >> from within that callback (or at a later
582	time). This will work even when the event loop does not support blocking	828	time). This will work even when the event loop does not support blocking
583	waits otherwise.	829	waits otherwise.
584		830
585	=item $bool = $cv->ready	831	=item $bool = $cv->ready
586		832
587	Returns true when the condition is "true", i.e. whether C<send> or	833	Returns true when the condition is "true", i.e. whether C<send> or
588	C<croak> have been called.	834	C<croak> have been called.
589		835
590	=item $cb = $cv->cb ([new callback])	836	=item $cb = $cv->cb ($cb->($cv))
591		837
592	This is a mutator function that returns the callback set and optionally	838	This is a mutator function that returns the callback set and optionally
593	replaces it before doing so.	839	replaces it before doing so.
594		840
595	The callback will be called when the condition becomes "true", i.e. when	841	The callback will be called when the condition becomes "true", i.e. when
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	842	C<send> or C<croak> are called, with the only argument being the
		843	condition variable itself. If the condition is already true, the
		844	callback is called immediately when it is set. Calling C<recv> inside
597	or at any later time is guaranteed not to block.	845	the callback or at any later time is guaranteed not to block.
598		846
599	=back	847	=back
600		848
		849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		850
		851	The available backend classes are (every class has its own manpage):
		852
		853	=over 4
		854
		855	=item Backends that are autoprobed when no other event loop can be found.
		856
		857	EV is the preferred backend when no other event loop seems to be in
		858	use. If EV is not installed, then AnyEvent will fall back to its own
		859	pure-perl implementation, which is available everywhere as it comes with
		860	AnyEvent itself.
		861
		862	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		863	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		864
		865	=item Backends that are transparently being picked up when they are used.
		866
		867	These will be used if they are already loaded when the first watcher
		868	is created, in which case it is assumed that the application is using
		869	them. This means that AnyEvent will automatically pick the right backend
		870	when the main program loads an event module before anything starts to
		871	create watchers. Nothing special needs to be done by the main program.
		872
		873	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		874	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		875	AnyEvent::Impl::Tk based on Tk, very broken.
		876	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		877	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		878	AnyEvent::Impl::Irssi used when running within irssi.
		879	AnyEvent::Impl::IOAsync based on IO::Async.
		880	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		881	AnyEvent::Impl::FLTK based on FLTK (fltk 2 binding).
		882
		883	=item Backends with special needs.
		884
		885	Qt requires the Qt::Application to be instantiated first, but will
		886	otherwise be picked up automatically. As long as the main program
		887	instantiates the application before any AnyEvent watchers are created,
		888	everything should just work.
		889
		890	AnyEvent::Impl::Qt based on Qt.
		891
		892	=item Event loops that are indirectly supported via other backends.
		893
		894	Some event loops can be supported via other modules:
		895
		896	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		897
		898	B<WxWidgets> has no support for watching file handles. However, you can
		899	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		900	polls 20 times per second, which was considered to be too horrible to even
		901	consider for AnyEvent.
		902
		903	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		904	backend, so it can be supported through POE.
		905
		906	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		907	load L<POE> when detecting them, in the hope that POE will pick them up,
		908	in which case everything will be automatic.
		909
		910	=back
		911
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	912	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		913
		914	These are not normally required to use AnyEvent, but can be useful to
		915	write AnyEvent extension modules.
		916
603	=over 4	917	=over 4
604		918
605	=item $AnyEvent::MODEL	919	=item $AnyEvent::MODEL
606		920
607	Contains C<undef> until the first watcher is being created. Then it	921	Contains C<undef> until the first watcher is being created, before the
		922	backend has been autodetected.
		923
608	contains the event model that is being used, which is the name of the	924	Afterwards it contains the event model that is being used, which is the
609	Perl class implementing the model. This class is usually one of the	925	name of the Perl class implementing the model. This class is usually one
610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	926	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	927	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
612		928	will be C<urxvt::anyevent>).
613	The known classes so far are:
614
615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
616	AnyEvent::Impl::Event based on Event, second best choice.
617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
618	AnyEvent::Impl::Glib based on Glib, third-best choice.
619	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623
624	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
629	it's adaptor.
630
631	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
632	autodetecting them.
633		929
634	=item AnyEvent::detect	930	=item AnyEvent::detect
635		931
636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	932	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
637	if necessary. You should only call this function right before you would	933	if necessary. You should only call this function right before you would
638	have created an AnyEvent watcher anyway, that is, as late as possible at	934	have created an AnyEvent watcher anyway, that is, as late as possible at
639	runtime.	935	runtime, and not e.g. during initialisation of your module.
		936
		937	The effect of calling this function is as if a watcher had been created
		938	(specifically, actions that happen "when the first watcher is created"
		939	happen when calling detetc as well).
		940
		941	If you need to do some initialisation before AnyEvent watchers are
		942	created, use C<post_detect>.
640		943
641	=item $guard = AnyEvent::post_detect { BLOCK }	944	=item $guard = AnyEvent::post_detect { BLOCK }
642		945
643	Arranges for the code block to be executed as soon as the event model is	946	Arranges for the code block to be executed as soon as the event model is
644	autodetected (or immediately if this has already happened).	947	autodetected (or immediately if that has already happened).
		948
		949	The block will be executed I<after> the actual backend has been detected
		950	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		951	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		952	other initialisations - see the sources of L<AnyEvent::Strict> or
		953	L<AnyEvent::AIO> to see how this is used.
		954
		955	The most common usage is to create some global watchers, without forcing
		956	event module detection too early, for example, L<AnyEvent::AIO> creates
		957	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		958	avoid autodetecting the event module at load time.
645		959
646	If called in scalar or list context, then it creates and returns an object	960	If called in scalar or list context, then it creates and returns an object
647	that automatically removes the callback again when it is destroyed. See	961	that automatically removes the callback again when it is destroyed (or
		962	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
648	L<Coro::BDB> for a case where this is useful.	963	a case where this is useful.
		964
		965	Example: Create a watcher for the IO::AIO module and store it in
		966	C<$WATCHER>, but do so only do so after the event loop is initialised.
		967
		968	our WATCHER;
		969
		970	my $guard = AnyEvent::post_detect {
		971	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		972	};
		973
		974	# the ||= is important in case post_detect immediately runs the block,
		975	# as to not clobber the newly-created watcher. assigning both watcher and
		976	# post_detect guard to the same variable has the advantage of users being
		977	# able to just C<undef $WATCHER> if the watcher causes them grief.
		978
		979	$WATCHER ||= $guard;
649		980
650	=item @AnyEvent::post_detect	981	=item @AnyEvent::post_detect
651		982
652	If there are any code references in this array (you can C<push> to it	983	If there are any code references in this array (you can C<push> to it
653	before or after loading AnyEvent), then they will called directly after	984	before or after loading AnyEvent), then they will be called directly
654	the event loop has been chosen.	985	after the event loop has been chosen.
655		986
656	You should check C<$AnyEvent::MODEL> before adding to this array, though:	987	You should check C<$AnyEvent::MODEL> before adding to this array, though:
657	if it contains a true value then the event loop has already been detected,	988	if it is defined then the event loop has already been detected, and the
658	and the array will be ignored.	989	array will be ignored.
659		990
660	Best use C<AnyEvent::post_detect { BLOCK }> instead.	991	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		992	it, as it takes care of these details.
		993
		994	This variable is mainly useful for modules that can do something useful
		995	when AnyEvent is used and thus want to know when it is initialised, but do
		996	not need to even load it by default. This array provides the means to hook
		997	into AnyEvent passively, without loading it.
		998
		999	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1000	together, you could put this into Coro (this is the actual code used by
		1001	Coro to accomplish this):
		1002
		1003	if (defined $AnyEvent::MODEL) {
		1004	# AnyEvent already initialised, so load Coro::AnyEvent
		1005	require Coro::AnyEvent;
		1006	} else {
		1007	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1008	# as soon as it is
		1009	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1010	}
		1011
		1012	=item AnyEvent::postpone { BLOCK }
		1013
		1014	Arranges for the block to be executed as soon as possible, but not before
		1015	the call itself returns. In practise, the block will be executed just
		1016	before the event loop polls for new events, or shortly afterwards.
		1017
		1018	This function never returns anything (to make the C<return postpone { ...
		1019	}> idiom more useful.
		1020
		1021	To understand the usefulness of this function, consider a function that
		1022	asynchronously does something for you and returns some transaction
		1023	object or guard to let you cancel the operation. For example,
		1024	C<AnyEvent::Socket::tcp_connect>:
		1025
		1026	# start a conenction attempt unless one is active
		1027	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1028	delete $self->{connect_guard};
		1029	...
		1030	};
		1031
		1032	Imagine that this function could instantly call the callback, for
		1033	example, because it detects an obvious error such as a negative port
		1034	number. Invoking the callback before the function returns causes problems
		1035	however: the callback will be called and will try to delete the guard
		1036	object. But since the function hasn't returned yet, there is nothing to
		1037	delete. When the function eventually returns it will assign the guard
		1038	object to C<< $self->{connect_guard} >>, where it will likely never be
		1039	deleted, so the program thinks it is still trying to connect.
		1040
		1041	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1042	callback directly on error:
		1043
		1044	$cb->(undef), return # signal error to callback, BAD!
		1045	if $some_error_condition;
		1046
		1047	It should use C<postpone>:
		1048
		1049	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1050	if $some_error_condition;
		1051
		1052	=item AnyEvent::log $level, $msg[, @args]
		1053
		1054	Log the given C<$msg> at the given C<$level>.
		1055
		1056	If L<AnyEvent::Log> is not loaded then this function makes a simple test
		1057	to see whether the message will be logged. If the test succeeds it will
		1058	load AnyEvent::Log and call C<AnyEvent::Log::log> - consequently, look at
		1059	the L<AnyEvent::Log> documentation for details.
		1060
		1061	If the test fails it will simply return. Right now this happens when a
		1062	numerical loglevel is used and it is larger than the level specified via
		1063	C<$ENV{PERL_ANYEVENT_VERBOSE}>.
		1064
		1065	If you want to sprinkle loads of logging calls around your code, consider
		1066	creating a logger callback with the C<AnyEvent::Log::logger> function,
		1067	which can reduce typing, codesize and can reduce the logging overhead
		1068	enourmously.
661		1069
662	=back	1070	=back
663		1071
664	=head1 WHAT TO DO IN A MODULE	1072	=head1 WHAT TO DO IN A MODULE
665		1073
…		…
676	because it will stall the whole program, and the whole point of using	1084	because it will stall the whole program, and the whole point of using
677	events is to stay interactive.	1085	events is to stay interactive.
678		1086
679	It is fine, however, to call C<< ->recv >> when the user of your module	1087	It is fine, however, to call C<< ->recv >> when the user of your module
680	requests it (i.e. if you create a http request object ad have a method	1088	requests it (i.e. if you create a http request object ad have a method
681	called C<results> that returns the results, it should call C<< ->recv >>	1089	called C<results> that returns the results, it may call C<< ->recv >>
682	freely, as the user of your module knows what she is doing. always).	1090	freely, as the user of your module knows what she is doing. Always).
683		1091
684	=head1 WHAT TO DO IN THE MAIN PROGRAM	1092	=head1 WHAT TO DO IN THE MAIN PROGRAM
685		1093
686	There will always be a single main program - the only place that should	1094	There will always be a single main program - the only place that should
687	dictate which event model to use.	1095	dictate which event model to use.
688		1096
689	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1097	If the program is not event-based, it need not do anything special, even
690	do anything special (it does not need to be event-based) and let AnyEvent	1098	when it depends on a module that uses an AnyEvent. If the program itself
691	decide which implementation to chose if some module relies on it.	1099	uses AnyEvent, but does not care which event loop is used, all it needs
		1100	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1101	available loop implementation.
692		1102
693	If the main program relies on a specific event model - for example, in	1103	If the main program relies on a specific event model - for example, in
694	Gtk2 programs you have to rely on the Glib module - you should load the	1104	Gtk2 programs you have to rely on the Glib module - you should load the
695	event module before loading AnyEvent or any module that uses it: generally	1105	event module before loading AnyEvent or any module that uses it: generally
696	speaking, you should load it as early as possible. The reason is that	1106	speaking, you should load it as early as possible. The reason is that
697	modules might create watchers when they are loaded, and AnyEvent will	1107	modules might create watchers when they are loaded, and AnyEvent will
698	decide on the event model to use as soon as it creates watchers, and it	1108	decide on the event model to use as soon as it creates watchers, and it
699	might chose the wrong one unless you load the correct one yourself.	1109	might choose the wrong one unless you load the correct one yourself.
700		1110
701	You can chose to use a pure-perl implementation by loading the	1111	You can chose to use a pure-perl implementation by loading the
702	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1112	C<AnyEvent::Loop> module, which gives you similar behaviour
703	everywhere, but letting AnyEvent chose the model is generally better.	1113	everywhere, but letting AnyEvent chose the model is generally better.
704		1114
705	=head2 MAINLOOP EMULATION	1115	=head2 MAINLOOP EMULATION
706		1116
707	Sometimes (often for short test scripts, or even standalone programs who	1117	Sometimes (often for short test scripts, or even standalone programs who
…		…
720		1130
721		1131
722	=head1 OTHER MODULES	1132	=head1 OTHER MODULES
723		1133
724	The following is a non-exhaustive list of additional modules that use	1134	The following is a non-exhaustive list of additional modules that use
725	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1135	AnyEvent as a client and can therefore be mixed easily with other
726	in the same program. Some of the modules come with AnyEvent, some are	1136	AnyEvent modules and other event loops in the same program. Some of the
727	available via CPAN.	1137	modules come as part of AnyEvent, the others are available via CPAN (see
		1138	L<http://search.cpan.org/search?m=module&q=anyevent%3A%3A*> for
		1139	a longer non-exhaustive list), and the list is heavily biased towards
		1140	modules of the AnyEvent author himself :)
728		1141
729	=over 4	1142	=over 4
730		1143
731	=item L<AnyEvent::Util>	1144	=item L<AnyEvent::Util>
732		1145
733	Contains various utility functions that replace often-used but blocking	1146	Contains various utility functions that replace often-used blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	1147	functions such as C<inet_aton> with event/callback-based versions.
735
736	=item L<AnyEvent::Handle>
737
738	Provide read and write buffers and manages watchers for reads and writes.
739		1148
740	=item L<AnyEvent::Socket>	1149	=item L<AnyEvent::Socket>
741		1150
742	Provides various utility functions for (internet protocol) sockets,	1151	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	1152	addresses and name resolution. Also functions to create non-blocking tcp
744	connections or tcp servers, with IPv6 and SRV record support and more.	1153	connections or tcp servers, with IPv6 and SRV record support and more.
745		1154
		1155	=item L<AnyEvent::Handle>
		1156
		1157	Provide read and write buffers, manages watchers for reads and writes,
		1158	supports raw and formatted I/O, I/O queued and fully transparent and
		1159	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1160
746	=item L<AnyEvent::DNS>	1161	=item L<AnyEvent::DNS>
747		1162
748	Provides rich asynchronous DNS resolver capabilities.	1163	Provides rich asynchronous DNS resolver capabilities.
749		1164
		1165	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1166
		1167	Implement event-based interfaces to the protocols of the same name (for
		1168	the curious, IGS is the International Go Server and FCP is the Freenet
		1169	Client Protocol).
		1170
		1171	=item L<AnyEvent::AIO>
		1172
		1173	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1174	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1175	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1176	file I/O, and much more.
		1177
		1178	=item L<AnyEvent::Filesys::Notify>
		1179
		1180	AnyEvent is good for non-blocking stuff, but it can't detect file or
		1181	path changes (e.g. "watch this directory for new files", "watch this
		1182	file for changes"). The L<AnyEvent::Filesys::Notify> module promises to
		1183	do just that in a portbale fashion, supporting inotify on GNU/Linux and
		1184	some weird, without doubt broken, stuff on OS X to monitor files. It can
		1185	fall back to blocking scans at regular intervals transparently on other
		1186	platforms, so it's about as portable as it gets.
		1187
		1188	(I haven't used it myself, but I haven't heard anybody complaining about
		1189	it yet).
		1190
		1191	=item L<AnyEvent::DBI>
		1192
		1193	Executes L<DBI> requests asynchronously in a proxy process for you,
		1194	notifying you in an event-based way when the operation is finished.
		1195
750	=item L<AnyEvent::HTTPD>	1196	=item L<AnyEvent::HTTPD>
751		1197
752	Provides a simple web application server framework.	1198	A simple embedded webserver.
753		1199
754	=item L<AnyEvent::FastPing>	1200	=item L<AnyEvent::FastPing>
755		1201
756	The fastest ping in the west.	1202	The fastest ping in the west.
757		1203
758	=item L<Net::IRC3>
759
760	AnyEvent based IRC client module family.
761
762	=item L<Net::XMPP2>
763
764	AnyEvent based XMPP (Jabber protocol) module family.
765
766	=item L<Net::FCP>
767
768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
769	of AnyEvent.
770
771	=item L<Event::ExecFlow>
772
773	High level API for event-based execution flow control.
774
775	=item L<Coro>	1204	=item L<Coro>
776		1205
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	1206	Has special support for AnyEvent via L<Coro::AnyEvent>, which allows you
		1207	to simply invert the flow control - don't call us, we will call you:
778		1208
779	=item L<AnyEvent::AIO>, L<IO::AIO>	1209	async {
		1210	Coro::AnyEvent::sleep 5; # creates a 5s timer and waits for it
		1211	print "5 seconds later!\n";
780		1212
781	Truly asynchronous I/O, should be in the toolbox of every event	1213	Coro::AnyEvent::readable *STDIN; # uses an I/O watcher
782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent	1214	my $line = <STDIN>; # works for ttys
783	together.
784		1215
785	=item L<AnyEvent::BDB>, L<BDB>	1216	AnyEvent::HTTP::http_get "url", Coro::rouse_cb;
786		1217	my ($body, $hdr) = Coro::rouse_wait;
787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses	1218	};
788	IO::AIO and AnyEvent together.
789
790	=item L<IO::Lambda>
791
792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793		1219
794	=back	1220	=back
795		1221
796	=cut	1222	=cut
797		1223
798	package AnyEvent;	1224	package AnyEvent;
799		1225
800	no warnings;	1226	# basically a tuned-down version of common::sense
801	use strict;	1227	sub common_sense {
		1228	# from common:.sense 3.5
		1229	local $^W;
		1230	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1231	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1232	$^H |= 0x00000600;
		1233	}
802		1234
		1235	BEGIN { AnyEvent::common_sense }
		1236
803	use Carp;	1237	use Carp ();
804		1238
805	our $VERSION = '4.05';	1239	our $VERSION = '6.14';
806	our $MODEL;	1240	our $MODEL;
807
808	our $AUTOLOAD;
809	our @ISA;	1241	our @ISA;
810
811	our @REGISTRY;	1242	our @REGISTRY;
812		1243	our $VERBOSE;
813	our $WIN32;	1244	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		1245	our $MAX_SIGNAL_LATENCY = $ENV{PERL_ANYEVENT_MAX_SIGNAL_LATENCY} || 10; # executes after the BEGIN block below (tainting!)
814		1246
815	BEGIN {	1247	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	1248	require "AnyEvent/constants.pl";
817	eval "sub WIN32(){ $win32 }";
818	}
819		1249
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1250	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
821		1251
822	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1252	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1253	if ${^TAINT};
823		1254
824	{	1255	$ENV{"PERL_ANYEVENT_$_"} = $ENV{"AE_$_"}
		1256	for grep s/^AE_// && !exists $ENV{"PERL_ANYEVENT_$_"}, keys %ENV;
		1257
		1258	@ENV{grep /^PERL_ANYEVENT_/, keys %ENV} = ()
		1259	if ${^TAINT};
		1260
		1261	# $ENV{PERL_ANYEVENT_xxx} now valid
		1262
		1263	$VERBOSE = length $ENV{PERL_ANYEVENT_VERBOSE} ? $ENV{PERL_ANYEVENT_VERBOSE}*1 : 4;
		1264
825	my $idx;	1265	my $idx;
826	$PROTOCOL{$_} = ++$idx	1266	$PROTOCOL{$_} = ++$idx
827	for reverse split /\s*,\s*/,	1267	for reverse split /\s*,\s*/,
828	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1268	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
829	}	1269	}
830		1270
		1271	our @post_detect;
		1272
		1273	sub post_detect(&) {
		1274	my ($cb) = @_;
		1275
		1276	push @post_detect, $cb;
		1277
		1278	defined wantarray
		1279	? bless \$cb, "AnyEvent::Util::postdetect"
		1280	: ()
		1281	}
		1282
		1283	sub AnyEvent::Util::postdetect::DESTROY {
		1284	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1285	}
		1286
		1287	our $POSTPONE_W;
		1288	our @POSTPONE;
		1289
		1290	sub _postpone_exec {
		1291	undef $POSTPONE_W;
		1292
		1293	&{ shift @POSTPONE }
		1294	while @POSTPONE;
		1295	}
		1296
		1297	sub postpone(&) {
		1298	push @POSTPONE, shift;
		1299
		1300	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1301
		1302	()
		1303	}
		1304
		1305	sub log($$;@) {
		1306	# only load the big bloated module when we actually are about to log something
		1307	if ($_[0] <= ($VERBOSE || 1)) { # also catches non-numeric levels(!) and fatal
		1308	local ($!, $@);
		1309	require AnyEvent::Log; # among other things, sets $VERBOSE to 9
		1310	# AnyEvent::Log overwrites this function
		1311	goto &log;
		1312	}
		1313
		1314	0 # not logged
		1315	}
		1316
		1317	sub _logger($;$) {
		1318	my ($level, $renabled) = @_;
		1319
		1320	$$renabled = $level <= $VERBOSE;
		1321
		1322	my $logger = [(caller)[0], $level, $renabled];
		1323
		1324	$AnyEvent::Log::LOGGER{$logger+0} = $logger;
		1325
		1326	# return unless defined wantarray;
		1327	#
		1328	# require AnyEvent::Util;
		1329	# my $guard = AnyEvent::Util::guard (sub {
		1330	# # "clean up"
		1331	# delete $LOGGER{$logger+0};
		1332	# });
		1333	#
		1334	# sub {
		1335	# return 0 unless $$renabled;
		1336	#
		1337	# $guard if 0; # keep guard alive, but don't cause runtime overhead
		1338	# require AnyEvent::Log unless $AnyEvent::Log::VERSION;
		1339	# package AnyEvent::Log;
		1340	# _log ($logger->[0], $level, @_) # logger->[0] has been converted at load time
		1341	# }
		1342	}
		1343
		1344	if (length $ENV{PERL_ANYEVENT_LOG}) {
		1345	require AnyEvent::Log; # AnyEvent::Log does the thing for us
		1346	}
		1347
831	my @models = (	1348	our @models = (
832	[EV:: => AnyEvent::Impl::EV::],	1349	[EV:: => AnyEvent::Impl::EV::],
833	[Event:: => AnyEvent::Impl::Event::],
834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1350	[AnyEvent::Loop:: => AnyEvent::Impl::Perl::],
835	# everything below here will not be autoprobed	1351	# everything below here will not (normally) be autoprobed
836	# as the pureperl backend should work everywhere	1352	# as the pure perl backend should work everywhere
837	# and is usually faster	1353	# and is usually faster
		1354	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package, so msut be near the top
		1355	[Event:: => AnyEvent::Impl::Event::], # slow, stable
		1356	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1357	# everything below here should not be autoloaded
		1358	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1359	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1360	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1361	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	1362	[Wx:: => AnyEvent::Impl::POE::],
844	[Prima:: => AnyEvent::Impl::POE::],	1363	[Prima:: => AnyEvent::Impl::POE::],
		1364	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1365	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1366	[FLTK:: => AnyEvent::Impl::FLTK::],
845	);	1367	);
846		1368
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1369	our @isa_hook;
848		1370
849	our @post_detect;	1371	sub _isa_set {
		1372	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
850		1373
		1374	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1375	for 1 .. $#pkg;
		1376
		1377	grep $_ && $_->[1], @isa_hook
		1378	and AE::_reset ();
		1379	}
		1380
		1381	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1382	sub _isa_hook($$;$) {
		1383	my ($i, $pkg, $reset_ae) = @_;
		1384
		1385	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1386
		1387	_isa_set;
		1388	}
		1389
		1390	# all autoloaded methods reserve the complete glob, not just the method slot.
		1391	# due to bugs in perls method cache implementation.
		1392	our @methods = qw(io timer time now now_update signal child idle condvar);
		1393
851	sub post_detect(&) {	1394	sub detect() {
852	my ($cb) = @_;	1395	return $MODEL if $MODEL; # some programs keep references to detect
853		1396
854	if ($MODEL) {	1397	# IO::Async::Loop::AnyEvent is extremely evil, refuse to work with it
855	$cb->();	1398	# the author knows about the problems and what it does to AnyEvent as a whole
		1399	# (and the ability of others to use AnyEvent), but simply wants to abuse AnyEvent
		1400	# anyway.
		1401	AnyEvent::log fatal => "AnyEvent: IO::Async::Loop::AnyEvent detected - that module is broken by\n"
		1402	. "design, abuses internals and breaks AnyEvent - will not continue."
		1403	if exists $INC{"IO/Async/Loop/AnyEvent.pm"};
856		1404
857	1	1405	local $!; # for good measure
		1406	local $SIG{__DIE__}; # we use eval
		1407
		1408	# free some memory
		1409	*detect = sub () { $MODEL };
		1410	# undef &func doesn't correctly update the method cache. grmbl.
		1411	# so we delete the whole glob. grmbl.
		1412	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1413	# a glob with an active sub. hrm. i hope it works, but perl is
		1414	# usually buggy in this department. sigh.
		1415	delete @{"AnyEvent::"}{@methods};
		1416	undef @methods;
		1417
		1418	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1419	my $model = $1;
		1420	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1421	if (eval "require $model") {
		1422	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.";
		1423	$MODEL = $model;
858	} else {	1424	} else {
859	push @post_detect, $cb;	1425	AnyEvent::log 4 => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
860		1426	}
861	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"
863	: ()
864	}	1427	}
865	}
866		1428
867	sub AnyEvent::Util::PostDetect::DESTROY {	1429	# check for already loaded models
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}
870
871	sub detect() {
872	unless ($MODEL) {	1430	unless ($MODEL) {
873	no strict 'refs';	1431	for (@REGISTRY, @models) {
874	local $SIG{__DIE__};	1432	my ($package, $model) = @$_;
875		1433	if (${"$package\::VERSION"} > 0) {
876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
877	my $model = "AnyEvent::Impl::$1";
878	if (eval "require $model") {	1434	if (eval "require $model") {
		1435	AnyEvent::log 7 => "autodetected model '$model', using it.";
879	$MODEL = $model;	1436	$MODEL = $model;
880	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1437	last;
881	} else {	1438	} else {
882	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1439	AnyEvent::log 8 => "detected event loop $package, but cannot load '$model', skipping: $@";
		1440	}
883	}	1441	}
884	}	1442	}
885		1443
886	# check for already loaded models
887	unless ($MODEL) {	1444	unless ($MODEL) {
		1445	# try to autoload a model
888	for (@REGISTRY, @models) {	1446	for (@REGISTRY, @models) {
889	my ($package, $model) = @$_;	1447	my ($package, $model) = @$_;
		1448	if (
		1449	eval "require $package"
890	if (${"$package\::VERSION"} > 0) {	1450	and ${"$package\::VERSION"} > 0
891	if (eval "require $model") {	1451	and eval "require $model"
		1452	) {
		1453	AnyEvent::log 7 => "autoloaded model '$model', using it.";
892	$MODEL = $model;	1454	$MODEL = $model;
893	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
894	last;	1455	last;
895	}
896	}	1456	}
897	}	1457	}
898		1458
899	unless ($MODEL) {	1459	$MODEL
900	# try to load a model	1460	or AnyEvent::log fatal => "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
		1461	}
		1462	}
901		1463
902	for (@REGISTRY, @models) {	1464	# free memory only needed for probing
903	my ($package, $model) = @$_;	1465	undef @models;
904	if (eval "require $package"	1466	undef @REGISTRY;
905	and ${"$package\::VERSION"} > 0	1467
906	and eval "require $model") {	1468	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
907	$MODEL = $model;	1469
908	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1470	# now nuke some methods that are overridden by the backend.
		1471	# SUPER usage is not allowed in these.
		1472	for (qw(time signal child idle)) {
		1473	undef &{"AnyEvent::Base::$_"}
		1474	if defined &{"$MODEL\::$_"};
		1475	}
		1476
		1477	_isa_set;
		1478
		1479	# we're officially open!
		1480
		1481	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1482	require AnyEvent::Strict;
		1483	}
		1484
		1485	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1486	require AnyEvent::Debug;
		1487	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1488	}
		1489
		1490	if (length $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1491	require AnyEvent::Socket;
		1492	require AnyEvent::Debug;
		1493
		1494	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1495	$shell =~ s/\$\$/$$/g;
		1496
		1497	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1498	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1499	}
		1500
		1501	# now the anyevent environment is set up as the user told us to, so
		1502	# call the actual user code - post detects
		1503
		1504	(shift @post_detect)->() while @post_detect;
		1505	undef @post_detect;
		1506
		1507	*post_detect = sub(&) {
		1508	shift->();
		1509
		1510	undef
		1511	};
		1512
		1513	$MODEL
		1514	}
		1515
		1516	for my $name (@methods) {
		1517	*$name = sub {
		1518	detect;
		1519	# we use goto because
		1520	# a) it makes the thunk more transparent
		1521	# b) it allows us to delete the thunk later
		1522	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1523	};
		1524	}
		1525
		1526	# utility function to dup a filehandle. this is used by many backends
		1527	# to support binding more than one watcher per filehandle (they usually
		1528	# allow only one watcher per fd, so we dup it to get a different one).
		1529	sub _dupfh($$;$$) {
		1530	my ($poll, $fh, $r, $w) = @_;
		1531
		1532	# cygwin requires the fh mode to be matching, unix doesn't
		1533	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1534
		1535	open my $fh2, $mode, $fh
		1536	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1537
		1538	# we assume CLOEXEC is already set by perl in all important cases
		1539
		1540	($fh2, $rw)
		1541	}
		1542
		1543	=head1 SIMPLIFIED AE API
		1544
		1545	Starting with version 5.0, AnyEvent officially supports a second, much
		1546	simpler, API that is designed to reduce the calling, typing and memory
		1547	overhead by using function call syntax and a fixed number of parameters.
		1548
		1549	See the L<AE> manpage for details.
		1550
		1551	=cut
		1552
		1553	package AE;
		1554
		1555	our $VERSION = $AnyEvent::VERSION;
		1556
		1557	sub _reset() {
		1558	eval q{
		1559	# fall back to the main API by default - backends and AnyEvent::Base
		1560	# implementations can overwrite these.
		1561
		1562	sub io($$$) {
		1563	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1564	}
		1565
		1566	sub timer($$$) {
		1567	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1568	}
		1569
		1570	sub signal($$) {
		1571	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1572	}
		1573
		1574	sub child($$) {
		1575	AnyEvent->child (pid => $_[0], cb => $_[1])
		1576	}
		1577
		1578	sub idle($) {
		1579	AnyEvent->idle (cb => $_[0]);
		1580	}
		1581
		1582	sub cv(;&) {
		1583	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1584	}
		1585
		1586	sub now() {
		1587	AnyEvent->now
		1588	}
		1589
		1590	sub now_update() {
		1591	AnyEvent->now_update
		1592	}
		1593
		1594	sub time() {
		1595	AnyEvent->time
		1596	}
		1597
		1598	*postpone = \&AnyEvent::postpone;
		1599	*log = \&AnyEvent::log;
		1600	};
		1601	die if $@;
		1602	}
		1603
		1604	BEGIN { _reset }
		1605
		1606	package AnyEvent::Base;
		1607
		1608	# default implementations for many methods
		1609
		1610	sub time {
		1611	eval q{ # poor man's autoloading {}
		1612	# probe for availability of Time::HiRes
		1613	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1614	*time = sub { Time::HiRes::time () };
		1615	*AE::time = \& Time::HiRes::time ;
		1616	*now = \&time;
		1617	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy.";
		1618	# if (eval "use POSIX (); (POSIX::times())...
		1619	} else {
		1620	*time = sub { CORE::time };
		1621	*AE::time = sub (){ CORE::time };
		1622	*now = \&time;
		1623	AnyEvent::log 3 => "using built-in time(), WARNING, no sub-second resolution!";
		1624	}
		1625	};
		1626	die if $@;
		1627
		1628	&time
		1629	}
		1630
		1631	*now = \&time;
		1632	sub now_update { }
		1633
		1634	sub _poll {
		1635	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1636	}
		1637
		1638	# default implementation for ->condvar
		1639	# in fact, the default should not be overwritten
		1640
		1641	sub condvar {
		1642	eval q{ # poor man's autoloading {}
		1643	*condvar = sub {
		1644	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1645	};
		1646
		1647	*AE::cv = sub (;&) {
		1648	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1649	};
		1650	};
		1651	die if $@;
		1652
		1653	&condvar
		1654	}
		1655
		1656	# default implementation for ->signal
		1657
		1658	our $HAVE_ASYNC_INTERRUPT;
		1659
		1660	sub _have_async_interrupt() {
		1661	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1662	&& eval "use Async::Interrupt 1.02 (); 1")
		1663	unless defined $HAVE_ASYNC_INTERRUPT;
		1664
		1665	$HAVE_ASYNC_INTERRUPT
		1666	}
		1667
		1668	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1669	our (%SIG_ASY, %SIG_ASY_W);
		1670	our ($SIG_COUNT, $SIG_TW);
		1671
		1672	# install a dummy wakeup watcher to reduce signal catching latency
		1673	# used by Impls
		1674	sub _sig_add() {
		1675	unless ($SIG_COUNT++) {
		1676	# try to align timer on a full-second boundary, if possible
		1677	my $NOW = AE::now;
		1678
		1679	$SIG_TW = AE::timer
		1680	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1681	$MAX_SIGNAL_LATENCY,
		1682	sub { } # just for the PERL_ASYNC_CHECK
		1683	;
		1684	}
		1685	}
		1686
		1687	sub _sig_del {
		1688	undef $SIG_TW
		1689	unless --$SIG_COUNT;
		1690	}
		1691
		1692	our $_sig_name_init; $_sig_name_init = sub {
		1693	eval q{ # poor man's autoloading {}
		1694	undef $_sig_name_init;
		1695
		1696	if (_have_async_interrupt) {
		1697	*sig2num = \&Async::Interrupt::sig2num;
		1698	*sig2name = \&Async::Interrupt::sig2name;
		1699	} else {
		1700	require Config;
		1701
		1702	my %signame2num;
		1703	@signame2num{ split ' ', $Config::Config{sig_name} }
		1704	= split ' ', $Config::Config{sig_num};
		1705
		1706	my @signum2name;
		1707	@signum2name[values %signame2num] = keys %signame2num;
		1708
		1709	*sig2num = sub($) {
		1710	$_[0] > 0 ? shift : $signame2num{+shift}
		1711	};
		1712	*sig2name = sub ($) {
		1713	$_[0] > 0 ? $signum2name[+shift] : shift
		1714	};
		1715	}
		1716	};
		1717	die if $@;
		1718	};
		1719
		1720	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1721	sub sig2name($) { &$_sig_name_init; &sig2name }
		1722
		1723	sub signal {
		1724	eval q{ # poor man's autoloading {}
		1725	# probe for availability of Async::Interrupt
		1726	if (_have_async_interrupt) {
		1727	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling.";
		1728
		1729	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1730	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1731
		1732	} else {
		1733	AnyEvent::log 8 => "using emulated perl signal handling with latency timer.";
		1734
		1735	if (AnyEvent::WIN32) {
		1736	require AnyEvent::Util;
		1737
		1738	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1739	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1740	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1741	} else {
		1742	pipe $SIGPIPE_R, $SIGPIPE_W;
		1743	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1744	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1745
		1746	# not strictly required, as $^F is normally 2, but let's make sure...
		1747	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1748	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1749	}
		1750
		1751	$SIGPIPE_R
		1752	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1753
		1754	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1755	}
		1756
		1757	*signal = $HAVE_ASYNC_INTERRUPT
		1758	? sub {
		1759	my (undef, %arg) = @_;
		1760
		1761	# async::interrupt
		1762	my $signal = sig2num $arg{signal};
		1763	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1764
		1765	$SIG_ASY{$signal} ||= new Async::Interrupt
		1766	cb => sub { undef $SIG_EV{$signal} },
		1767	signal => $signal,
		1768	pipe => [$SIGPIPE_R->filenos],
		1769	pipe_autodrain => 0,
		1770	;
		1771
		1772	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1773	}
		1774	: sub {
		1775	my (undef, %arg) = @_;
		1776
		1777	# pure perl
		1778	my $signal = sig2name $arg{signal};
		1779	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1780
		1781	$SIG{$signal} ||= sub {
909	last;	1782	local $!;
		1783	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1784	undef $SIG_EV{$signal};
910	}	1785	};
		1786
		1787	# can't do signal processing without introducing races in pure perl,
		1788	# so limit the signal latency.
		1789	_sig_add;
		1790
		1791	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1792	}
		1793	;
		1794
		1795	*AnyEvent::Base::signal::DESTROY = sub {
		1796	my ($signal, $cb) = @{$_[0]};
		1797
		1798	_sig_del;
		1799
		1800	delete $SIG_CB{$signal}{$cb};
		1801
		1802	$HAVE_ASYNC_INTERRUPT
		1803	? delete $SIG_ASY{$signal}
		1804	: # delete doesn't work with older perls - they then
		1805	# print weird messages, or just unconditionally exit
		1806	# instead of getting the default action.
		1807	undef $SIG{$signal}
		1808	unless keys %{ $SIG_CB{$signal} };
		1809	};
		1810
		1811	*_signal_exec = sub {
		1812	$HAVE_ASYNC_INTERRUPT
		1813	? $SIGPIPE_R->drain
		1814	: sysread $SIGPIPE_R, (my $dummy), 9;
		1815
		1816	while (%SIG_EV) {
		1817	for (keys %SIG_EV) {
		1818	delete $SIG_EV{$_};
		1819	&$_ for values %{ $SIG_CB{$_} || {} };
911	}	1820	}
912
913	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
915	}	1821	}
916	}	1822	};
917
918	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
920
921	(shift @post_detect)->() while @post_detect;
922	}
923
924	$MODEL
925	}
926
927	sub AUTOLOAD {
928	(my $func = $AUTOLOAD) =~ s/.*://;
929
930	$method{$func}
931	or croak "$func: not a valid method for AnyEvent objects";
932
933	detect unless $MODEL;
934
935	my $class = shift;
936	$class->$func (@_);
937	}
938
939	package AnyEvent::Base;
940
941	# default implementation for now and time
942
943	use Time::HiRes ();
944
945	sub time { Time::HiRes::time }
946	sub now { Time::HiRes::time }
947
948	# default implementation for ->condvar
949
950	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
952	}
953
954	# default implementation for ->signal
955
956	our %SIG_CB;
957
958	sub signal {
959	my (undef, %arg) = @_;
960
961	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";
963
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
965	$SIG{$signal} ||= sub {
966	$_->() for values %{ $SIG_CB{$signal} || {} };
967	};	1823	};
		1824	die if $@;
968		1825
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1826	&signal
970	}
971
972	sub AnyEvent::Base::Signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};
974
975	delete $SIG_CB{$signal}{$cb};
976
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
978	}	1827	}
979		1828
980	# default implementation for ->child	1829	# default implementation for ->child
981		1830
982	our %PID_CB;	1831	our %PID_CB;
983	our $CHLD_W;	1832	our $CHLD_W;
984	our $CHLD_DELAY_W;	1833	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;
987		1834
988	sub _child_wait {	1835	# used by many Impl's
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1836	sub _emit_childstatus($$) {
		1837	my (undef, $rpid, $rstatus) = @_;
		1838
		1839	$_->($rpid, $rstatus)
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1840	for values %{ $PID_CB{$rpid} || {} },
991	(values %{ $PID_CB{0} || {} });	1841	values %{ $PID_CB{0} || {} };
992	}
993
994	undef $PID_IDLE;
995	}
996
997	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.
999	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1000	undef $CHLD_DELAY_W;
1001	&_child_wait;
1002	});
1003	}	1842	}
1004		1843
1005	sub child {	1844	sub child {
		1845	eval q{ # poor man's autoloading {}
		1846	*_sigchld = sub {
		1847	my $pid;
		1848
		1849	AnyEvent->_emit_childstatus ($pid, $?)
		1850	while ($pid = waitpid -1, WNOHANG) > 0;
		1851	};
		1852
		1853	*child = sub {
1006	my (undef, %arg) = @_;	1854	my (undef, %arg) = @_;
1007		1855
1008	defined (my $pid = $arg{pid} + 0)	1856	my $pid = $arg{pid};
1009	or Carp::croak "required option 'pid' is missing";	1857	my $cb = $arg{cb};
1010		1858
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1859	$PID_CB{$pid}{$cb+0} = $cb;
1012		1860
1013	unless ($WNOHANG) {
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015	}
1016
1017	unless ($CHLD_W) {	1861	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1862	$CHLD_W = AE::signal CHLD => \&_sigchld;
1019	# child could be a zombie already, so make at least one round	1863	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1864	&_sigchld;
1021	}	1865	}
1022		1866
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1867	bless [$pid, $cb+0], "AnyEvent::Base::child"
1024	}	1868	};
1025		1869
1026	sub AnyEvent::Base::Child::DESTROY {	1870	*AnyEvent::Base::child::DESTROY = sub {
1027	my ($pid, $cb) = @{$_[0]};	1871	my ($pid, $icb) = @{$_[0]};
1028		1872
1029	delete $PID_CB{$pid}{$cb};	1873	delete $PID_CB{$pid}{$icb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1874	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1875
1032	undef $CHLD_W unless keys %PID_CB;	1876	undef $CHLD_W unless keys %PID_CB;
		1877	};
		1878	};
		1879	die if $@;
		1880
		1881	&child
		1882	}
		1883
		1884	# idle emulation is done by simply using a timer, regardless
		1885	# of whether the process is idle or not, and not letting
		1886	# the callback use more than 50% of the time.
		1887	sub idle {
		1888	eval q{ # poor man's autoloading {}
		1889	*idle = sub {
		1890	my (undef, %arg) = @_;
		1891
		1892	my ($cb, $w, $rcb) = $arg{cb};
		1893
		1894	$rcb = sub {
		1895	if ($cb) {
		1896	$w = AE::time;
		1897	&$cb;
		1898	$w = AE::time - $w;
		1899
		1900	# never use more then 50% of the time for the idle watcher,
		1901	# within some limits
		1902	$w = 0.0001 if $w < 0.0001;
		1903	$w = 5 if $w > 5;
		1904
		1905	$w = AE::timer $w, 0, $rcb;
		1906	} else {
		1907	# clean up...
		1908	undef $w;
		1909	undef $rcb;
		1910	}
		1911	};
		1912
		1913	$w = AE::timer 0.05, 0, $rcb;
		1914
		1915	bless \\$cb, "AnyEvent::Base::idle"
		1916	};
		1917
		1918	*AnyEvent::Base::idle::DESTROY = sub {
		1919	undef $${$_[0]};
		1920	};
		1921	};
		1922	die if $@;
		1923
		1924	&idle
1033	}	1925	}
1034		1926
1035	package AnyEvent::CondVar;	1927	package AnyEvent::CondVar;
1036		1928
1037	our @ISA = AnyEvent::CondVar::Base::;	1929	our @ISA = AnyEvent::CondVar::Base::;
1038		1930
		1931	# only to be used for subclassing
		1932	sub new {
		1933	my $class = shift;
		1934	bless AnyEvent->condvar (@_), $class
		1935	}
		1936
1039	package AnyEvent::CondVar::Base;	1937	package AnyEvent::CondVar::Base;
1040		1938
1041	use overload	1939	#use overload
1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1940	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1043	fallback => 1;	1941	# fallback => 1;
		1942
		1943	# save 300+ kilobytes by dirtily hardcoding overloading
		1944	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1945	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1946	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1947	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1948
		1949	our $WAITING;
1044		1950
1045	sub _send {	1951	sub _send {
1046	# nop	1952	# nop
		1953	}
		1954
		1955	sub _wait {
		1956	AnyEvent->_poll until $_[0]{_ae_sent};
1047	}	1957	}
1048		1958
1049	sub send {	1959	sub send {
1050	my $cv = shift;	1960	my $cv = shift;
1051	$cv->{_ae_sent} = [@_];	1961	$cv->{_ae_sent} = [@_];
…		…
1060		1970
1061	sub ready {	1971	sub ready {
1062	$_[0]{_ae_sent}	1972	$_[0]{_ae_sent}
1063	}	1973	}
1064		1974
1065	sub _wait {
1066	AnyEvent->one_event while !$_[0]{_ae_sent};
1067	}
1068
1069	sub recv {	1975	sub recv {
		1976	unless ($_[0]{_ae_sent}) {
		1977	$WAITING
		1978	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1979
		1980	local $WAITING = 1;
1070	$_[0]->_wait;	1981	$_[0]->_wait;
		1982	}
1071		1983
1072	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1984	$_[0]{_ae_croak}
1073	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1985	and Carp::croak $_[0]{_ae_croak};
		1986
		1987	wantarray
		1988	? @{ $_[0]{_ae_sent} }
		1989	: $_[0]{_ae_sent}[0]
1074	}	1990	}
1075		1991
1076	sub cb {	1992	sub cb {
1077	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1993	my $cv = shift;
		1994
		1995	@_
		1996	and $cv->{_ae_cb} = shift
		1997	and $cv->{_ae_sent}
		1998	and (delete $cv->{_ae_cb})->($cv);
		1999
1078	$_[0]{_ae_cb}	2000	$cv->{_ae_cb}
1079	}	2001	}
1080		2002
1081	sub begin {	2003	sub begin {
1082	++$_[0]{_ae_counter};	2004	++$_[0]{_ae_counter};
1083	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	2005	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1088	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	2010	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1089	}	2011	}
1090		2012
1091	# undocumented/compatibility with pre-3.4	2013	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	2014	*broadcast = \&send;
1093	*wait = \&_wait;	2015	*wait = \&recv;
		2016
		2017	=head1 ERROR AND EXCEPTION HANDLING
		2018
		2019	In general, AnyEvent does not do any error handling - it relies on the
		2020	caller to do that if required. The L<AnyEvent::Strict> module (see also
		2021	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		2022	checking of all AnyEvent methods, however, which is highly useful during
		2023	development.
		2024
		2025	As for exception handling (i.e. runtime errors and exceptions thrown while
		2026	executing a callback), this is not only highly event-loop specific, but
		2027	also not in any way wrapped by this module, as this is the job of the main
		2028	program.
		2029
		2030	The pure perl event loop simply re-throws the exception (usually
		2031	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		2032	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		2033	so on.
		2034
		2035	=head1 ENVIRONMENT VARIABLES
		2036
		2037	AnyEvent supports a number of environment variables that tune the
		2038	runtime behaviour. They are usually evaluated when AnyEvent is
		2039	loaded, initialised, or a submodule that uses them is loaded. Many of
		2040	them also cause AnyEvent to load additional modules - for example,
		2041	C<PERL_ANYEVENT_DEBUG_WRAP> causes the L<AnyEvent::Debug> module to be
		2042	loaded.
		2043
		2044	All the environment variables documented here start with
		2045	C<PERL_ANYEVENT_>, which is what AnyEvent considers its own
		2046	namespace. Other modules are encouraged (but by no means required) to use
		2047	C<PERL_ANYEVENT_SUBMODULE> if they have registered the AnyEvent::Submodule
		2048	namespace on CPAN, for any submodule. For example, L<AnyEvent::HTTP> could
		2049	be expected to use C<PERL_ANYEVENT_HTTP_PROXY> (it should not access env
		2050	variables starting with C<AE_>, see below).
		2051
		2052	All variables can also be set via the C<AE_> prefix, that is, instead
		2053	of setting C<PERL_ANYEVENT_VERBOSE> you can also set C<AE_VERBOSE>. In
		2054	case there is a clash btween anyevent and another program that uses
		2055	C<AE_something> you can set the corresponding C<PERL_ANYEVENT_something>
		2056	variable to the empty string, as those variables take precedence.
		2057
		2058	When AnyEvent is first loaded, it copies all C<AE_xxx> env variables
		2059	to their C<PERL_ANYEVENT_xxx> counterpart unless that variable already
		2060	exists. If taint mode is on, then AnyEvent will remove I<all> environment
		2061	variables starting with C<PERL_ANYEVENT_> from C<%ENV> (or replace them
		2062	with C<undef> or the empty string, if the corresaponding C<AE_> variable
		2063	is set).
		2064
		2065	The exact algorithm is currently:
		2066
		2067	1. if taint mode enabled, delete all PERL_ANYEVENT_xyz variables from %ENV
		2068	2. copy over AE_xyz to PERL_ANYEVENT_xyz unless the latter alraedy exists
		2069	3. if taint mode enabled, set all PERL_ANYEVENT_xyz variables to undef.
		2070
		2071	This ensures that child processes will not see the C<AE_> variables.
		2072
		2073	The following environment variables are currently known to AnyEvent:
		2074
		2075	=over 4
		2076
		2077	=item C<PERL_ANYEVENT_VERBOSE>
		2078
		2079	By default, AnyEvent will log messages with loglevel C<4> (C<error>) or
		2080	higher (see L<AnyEvent::Log>). You can set this environment variable to a
		2081	numerical loglevel to make AnyEvent more (or less) talkative.
		2082
		2083	If you want to do more than just set the global logging level
		2084	you should have a look at C<PERL_ANYEVENT_LOG>, which allows much more
		2085	complex specifications.
		2086
		2087	When set to C<0> (C<off>), then no messages whatsoever will be logged with
		2088	everything else at defaults.
		2089
		2090	When set to C<5> or higher (C<warn>), AnyEvent warns about unexpected
		2091	conditions, such as not being able to load the event model specified by
		2092	C<PERL_ANYEVENT_MODEL>, or a guard callback throwing an exception - this
		2093	is the minimum recommended level for use during development.
		2094
		2095	When set to C<7> or higher (info), AnyEvent reports which event model it
		2096	chooses.
		2097
		2098	When set to C<8> or higher (debug), then AnyEvent will report extra
		2099	information on which optional modules it loads and how it implements
		2100	certain features.
		2101
		2102	=item C<PERL_ANYEVENT_LOG>
		2103
		2104	Accepts rather complex logging specifications. For example, you could log
		2105	all C<debug> messages of some module to stderr, warnings and above to
		2106	stderr, and errors and above to syslog, with:
		2107
		2108	PERL_ANYEVENT_LOG=Some::Module=debug,+log:filter=warn,+%syslog:%syslog=error,syslog
		2109
		2110	For the rather extensive details, see L<AnyEvent::Log>.
		2111
		2112	This variable is evaluated when AnyEvent (or L<AnyEvent::Log>) is loaded,
		2113	so will take effect even before AnyEvent has initialised itself.
		2114
		2115	Note that specifying this environment variable causes the L<AnyEvent::Log>
		2116	module to be loaded, while C<PERL_ANYEVENT_VERBOSE> does not, so only
		2117	using the latter saves a few hundred kB of memory unless a module
		2118	explicitly needs the extra features of AnyEvent::Log.
		2119
		2120	=item C<PERL_ANYEVENT_STRICT>
		2121
		2122	AnyEvent does not do much argument checking by default, as thorough
		2123	argument checking is very costly. Setting this variable to a true value
		2124	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		2125	check the arguments passed to most method calls. If it finds any problems,
		2126	it will croak.
		2127
		2128	In other words, enables "strict" mode.
		2129
		2130	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		2131	>>, it is definitely recommended to keep it off in production. Keeping
		2132	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2133	can be very useful, however.
		2134
		2135	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2136
		2137	If this env variable is nonempty, then its contents will be interpreted by
		2138	C<AnyEvent::Socket::parse_hostport> and C<AnyEvent::Debug::shell> (after
		2139	replacing every occurance of C<$$> by the process pid). The shell object
		2140	is saved in C<$AnyEvent::Debug::SHELL>.
		2141
		2142	This happens when the first watcher is created.
		2143
		2144	For example, to bind a debug shell on a unix domain socket in
		2145	F<< /tmp/debug<pid>.sock >>, you could use this:
		2146
		2147	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2148	# connect with e.g.: socat readline /tmp/debug123.sock
		2149
		2150	Or to bind to tcp port 4545 on localhost:
		2151
		2152	PERL_ANYEVENT_DEBUG_SHELL=127.0.0.1:4545 perlprog
		2153	# connect with e.g.: telnet localhost 4545
		2154
		2155	Note that creating sockets in F</tmp> or on localhost is very unsafe on
		2156	multiuser systems.
		2157
		2158	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2159
		2160	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2161	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		2162
		2163	=item C<PERL_ANYEVENT_MODEL>
		2164
		2165	This can be used to specify the event model to be used by AnyEvent, before
		2166	auto detection and -probing kicks in.
		2167
		2168	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2169	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		2170	resulting module name is loaded and - if the load was successful - used as
		2171	event model backend. If it fails to load then AnyEvent will proceed with
		2172	auto detection and -probing.
		2173
		2174	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2175	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2176	the end of a string designates a module name and quotes it appropriately).
		2177
		2178	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2179	could start your program like this:
		2180
		2181	PERL_ANYEVENT_MODEL=Perl perl ...
		2182
		2183	=item C<PERL_ANYEVENT_PROTOCOLS>
		2184
		2185	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2186	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2187	of auto probing).
		2188
		2189	Must be set to a comma-separated list of protocols or address families,
		2190	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2191	used, and preference will be given to protocols mentioned earlier in the
		2192	list.
		2193
		2194	This variable can effectively be used for denial-of-service attacks
		2195	against local programs (e.g. when setuid), although the impact is likely
		2196	small, as the program has to handle conenction and other failures anyways.
		2197
		2198	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2199	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2200	- only support IPv4, never try to resolve or contact IPv6
		2201	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2202	IPv6, but prefer IPv6 over IPv4.
		2203
		2204	=item C<PERL_ANYEVENT_HOSTS>
		2205
		2206	This variable, if specified, overrides the F</etc/hosts> file used by
		2207	L<AnyEvent::Socket>C<::resolve_sockaddr>, i.e. hosts aliases will be read
		2208	from that file instead.
		2209
		2210	=item C<PERL_ANYEVENT_EDNS0>
		2211
		2212	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension for
		2213	DNS. This extension is generally useful to reduce DNS traffic, especially
		2214	when DNSSEC is involved, but some (broken) firewalls drop such DNS
		2215	packets, which is why it is off by default.
		2216
		2217	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2218	EDNS0 in its DNS requests.
		2219
		2220	=item C<PERL_ANYEVENT_MAX_FORKS>
		2221
		2222	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2223	will create in parallel.
		2224
		2225	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2226
		2227	The default value for the C<max_outstanding> parameter for the default DNS
		2228	resolver - this is the maximum number of parallel DNS requests that are
		2229	sent to the DNS server.
		2230
		2231	=item C<PERL_ANYEVENT_MAX_SIGNAL_LATENCY>
		2232
		2233	Perl has inherently racy signal handling (you can basically choose between
		2234	losing signals and memory corruption) - pure perl event loops (including
		2235	C<AnyEvent::Loop>, when C<Async::Interrupt> isn't available) therefore
		2236	have to poll regularly to avoid losing signals.
		2237
		2238	Some event loops are racy, but don't poll regularly, and some event loops
		2239	are written in C but are still racy. For those event loops, AnyEvent
		2240	installs a timer that regularly wakes up the event loop.
		2241
		2242	By default, the interval for this timer is C<10> seconds, but you can
		2243	override this delay with this environment variable (or by setting
		2244	the C<$AnyEvent::MAX_SIGNAL_LATENCY> variable before creating signal
		2245	watchers).
		2246
		2247	Lower values increase CPU (and energy) usage, higher values can introduce
		2248	long delays when reaping children or waiting for signals.
		2249
		2250	The L<AnyEvent::Async> module, if available, will be used to avoid this
		2251	polling (with most event loops).
		2252
		2253	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2254
		2255	The absolute path to a F<resolv.conf>-style file to use instead of
		2256	F</etc/resolv.conf> (or the OS-specific configuration) in the default
		2257	resolver, or the empty string to select the default configuration.
		2258
		2259	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2260
		2261	When neither C<ca_file> nor C<ca_path> was specified during
		2262	L<AnyEvent::TLS> context creation, and either of these environment
		2263	variables are nonempty, they will be used to specify CA certificate
		2264	locations instead of a system-dependent default.
		2265
		2266	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2267
		2268	When these are set to C<1>, then the respective modules are not
		2269	loaded. Mostly good for testing AnyEvent itself.
		2270
		2271	=back
1094		2272
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2273	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		2274
1097	This is an advanced topic that you do not normally need to use AnyEvent in	2275	This is an advanced topic that you do not normally need to use AnyEvent in
1098	a module. This section is only of use to event loop authors who want to	2276	a module. This section is only of use to event loop authors who want to
…		…
1132		2310
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2311	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	2312	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	2313	C<die>. This still works with most modules/usages, and blocking calls must
1136	not be done in an interactive application, so it makes sense.	2314	not be done in an interactive application, so it makes sense.
1137
1138	=head1 ENVIRONMENT VARIABLES
1139
1140	The following environment variables are used by this module:
1141
1142	=over 4
1143
1144	=item C<PERL_ANYEVENT_VERBOSE>
1145
1146	By default, AnyEvent will be completely silent except in fatal
1147	conditions. You can set this environment variable to make AnyEvent more
1148	talkative.
1149
1150	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151	conditions, such as not being able to load the event model specified by
1152	C<PERL_ANYEVENT_MODEL>.
1153
1154	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155	model it chooses.
1156
1157	=item C<PERL_ANYEVENT_MODEL>
1158
1159	This can be used to specify the event model to be used by AnyEvent, before
1160	auto detection and -probing kicks in. It must be a string consisting
1161	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162	and the resulting module name is loaded and if the load was successful,
1163	used as event model. If it fails to load AnyEvent will proceed with
1164	auto detection and -probing.
1165
1166	This functionality might change in future versions.
1167
1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169	could start your program like this:
1170
1171	PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173	=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177	of auto probing).
1178
1179	Must be set to a comma-separated list of protocols or address families,
1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181	used, and preference will be given to protocols mentioned earlier in the
1182	list.
1183
1184	This variable can effectively be used for denial-of-service attacks
1185	against local programs (e.g. when setuid), although the impact is likely
1186	small, as the program has to handle connection errors already-
1187
1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190	- only support IPv4, never try to resolve or contact IPv6
1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192	IPv6, but prefer IPv6 over IPv4.
1193
1194	=item C<PERL_ANYEVENT_EDNS0>
1195
1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197	for DNS. This extension is generally useful to reduce DNS traffic, but
1198	some (broken) firewalls drop such DNS packets, which is why it is off by
1199	default.
1200
1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202	EDNS0 in its DNS requests.
1203
1204	=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207	will create in parallel.
1208
1209	=back
1210		2315
1211	=head1 EXAMPLE PROGRAM	2316	=head1 EXAMPLE PROGRAM
1212		2317
1213	The following program uses an I/O watcher to read data from STDIN, a timer	2318	The following program uses an I/O watcher to read data from STDIN, a timer
1214	to display a message once per second, and a condition variable to quit the	2319	to display a message once per second, and a condition variable to quit the
…		…
1227	warn "read: $input\n"; # output what has been read	2332	warn "read: $input\n"; # output what has been read
1228	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2333	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1229	},	2334	},
1230	);	2335	);
1231		2336
1232	my $time_watcher; # can only be used once
1233
1234	sub new_timer {
1235	$timer = AnyEvent->timer (after => 1, cb => sub {	2337	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1236	warn "timeout\n"; # print 'timeout' about every second	2338	warn "timeout\n"; # print 'timeout' at most every second
1237	&new_timer; # and restart the time
1238	});	2339	});
1239	}
1240
1241	new_timer; # create first timer
1242		2340
1243	$cv->recv; # wait until user enters /^q/i	2341	$cv->recv; # wait until user enters /^q/i
1244		2342
1245	=head1 REAL-WORLD EXAMPLE	2343	=head1 REAL-WORLD EXAMPLE
1246		2344
…		…
1319		2417
1320	The actual code goes further and collects all errors (C<die>s, exceptions)	2418	The actual code goes further and collects all errors (C<die>s, exceptions)
1321	that occurred during request processing. The C<result> method detects	2419	that occurred during request processing. The C<result> method detects
1322	whether an exception as thrown (it is stored inside the $txn object)	2420	whether an exception as thrown (it is stored inside the $txn object)
1323	and just throws the exception, which means connection errors and other	2421	and just throws the exception, which means connection errors and other
1324	problems get reported tot he code that tries to use the result, not in a	2422	problems get reported to the code that tries to use the result, not in a
1325	random callback.	2423	random callback.
1326		2424
1327	All of this enables the following usage styles:	2425	All of this enables the following usage styles:
1328		2426
1329	1. Blocking:	2427	1. Blocking:
…		…
1377	through AnyEvent. The benchmark creates a lot of timers (with a zero	2475	through AnyEvent. The benchmark creates a lot of timers (with a zero
1378	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2476	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1379	which it is), lets them fire exactly once and destroys them again.	2477	which it is), lets them fire exactly once and destroys them again.
1380		2478
1381	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2479	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1382	distribution.	2480	distribution. It uses the L<AE> interface, which makes a real difference
		2481	for the EV and Perl backends only.
1383		2482
1384	=head3 Explanation of the columns	2483	=head3 Explanation of the columns
1385		2484
1386	I<watcher> is the number of event watchers created/destroyed. Since	2485	I<watcher> is the number of event watchers created/destroyed. Since
1387	different event models feature vastly different performances, each event	2486	different event models feature vastly different performances, each event
…		…
1408	watcher.	2507	watcher.
1409		2508
1410	=head3 Results	2509	=head3 Results
1411		2510
1412	name watchers bytes create invoke destroy comment	2511	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2512	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1414	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2513	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1415	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2514	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1416	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2515	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1417	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2516	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1418	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2517	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2518	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2519	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1419	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2520	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1420	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2521	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1421	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2522	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2523	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1423		2524
1424	=head3 Discussion	2525	=head3 Discussion
1425		2526
1426	The benchmark does I<not> measure scalability of the event loop very	2527	The benchmark does I<not> measure scalability of the event loop very
1427	well. For example, a select-based event loop (such as the pure perl one)	2528	well. For example, a select-based event loop (such as the pure perl one)
…		…
1439	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2540	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1440	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2541	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1441	cycles with POE.	2542	cycles with POE.
1442		2543
1443	C<EV> is the sole leader regarding speed and memory use, which are both	2544	C<EV> is the sole leader regarding speed and memory use, which are both
1444	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2545	maximal/minimal, respectively. When using the L<AE> API there is zero
		2546	overhead (when going through the AnyEvent API create is about 5-6 times
		2547	slower, with other times being equal, so still uses far less memory than
1445	far less memory than any other event loop and is still faster than Event	2548	any other event loop and is still faster than Event natively).
1446	natively.
1447		2549
1448	The pure perl implementation is hit in a few sweet spots (both the	2550	The pure perl implementation is hit in a few sweet spots (both the
1449	constant timeout and the use of a single fd hit optimisations in the perl	2551	constant timeout and the use of a single fd hit optimisations in the perl
1450	interpreter and the backend itself). Nevertheless this shows that it	2552	interpreter and the backend itself). Nevertheless this shows that it
1451	adds very little overhead in itself. Like any select-based backend its	2553	adds very little overhead in itself. Like any select-based backend its
1452	performance becomes really bad with lots of file descriptors (and few of	2554	performance becomes really bad with lots of file descriptors (and few of
1453	them active), of course, but this was not subject of this benchmark.	2555	them active), of course, but this was not subject of this benchmark.
1454		2556
1455	The C<Event> module has a relatively high setup and callback invocation	2557	The C<Event> module has a relatively high setup and callback invocation
1456	cost, but overall scores in on the third place.	2558	cost, but overall scores in on the third place.
		2559
		2560	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2561	when using its pure perl backend.
1457		2562
1458	C<Glib>'s memory usage is quite a bit higher, but it features a	2563	C<Glib>'s memory usage is quite a bit higher, but it features a
1459	faster callback invocation and overall ends up in the same class as	2564	faster callback invocation and overall ends up in the same class as
1460	C<Event>. However, Glib scales extremely badly, doubling the number of	2565	C<Event>. However, Glib scales extremely badly, doubling the number of
1461	watchers increases the processing time by more than a factor of four,	2566	watchers increases the processing time by more than a factor of four,
…		…
1496	(even when used without AnyEvent), but most event loops have acceptable	2601	(even when used without AnyEvent), but most event loops have acceptable
1497	performance with or without AnyEvent.	2602	performance with or without AnyEvent.
1498		2603
1499	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2604	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1500	the actual event loop, only with extremely fast event loops such as EV	2605	the actual event loop, only with extremely fast event loops such as EV
1501	adds AnyEvent significant overhead.	2606	does AnyEvent add significant overhead.
1502		2607
1503	=item * You should avoid POE like the plague if you want performance or	2608	=item * You should avoid POE like the plague if you want performance or
1504	reasonable memory usage.	2609	reasonable memory usage.
1505		2610
1506	=back	2611	=back
…		…
1522	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2627	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1523	(1%) are active. This mirrors the activity of large servers with many	2628	(1%) are active. This mirrors the activity of large servers with many
1524	connections, most of which are idle at any one point in time.	2629	connections, most of which are idle at any one point in time.
1525		2630
1526	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2631	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1527	distribution.	2632	distribution. It uses the L<AE> interface, which makes a real difference
		2633	for the EV and Perl backends only.
1528		2634
1529	=head3 Explanation of the columns	2635	=head3 Explanation of the columns
1530		2636
1531	I<sockets> is the number of sockets, and twice the number of "servers" (as	2637	I<sockets> is the number of sockets, and twice the number of "servers" (as
1532	each server has a read and write socket end).	2638	each server has a read and write socket end).
…		…
1539	it to another server. This includes deleting the old timeout and creating	2645	it to another server. This includes deleting the old timeout and creating
1540	a new one that moves the timeout into the future.	2646	a new one that moves the timeout into the future.
1541		2647
1542	=head3 Results	2648	=head3 Results
1543		2649
1544	name sockets create request	2650	name sockets create request
1545	EV 20000 69.01 11.16	2651	EV 20000 62.66 7.99
1546	Perl 20000 73.32 35.87	2652	Perl 20000 68.32 32.64
1547	Event 20000 212.62 257.32	2653	IOAsync 20000 174.06 101.15 epoll
1548	Glib 20000 651.16 1896.30	2654	IOAsync 20000 174.67 610.84 poll
		2655	Event 20000 202.69 242.91
		2656	Glib 20000 557.01 1689.52
1549	POE 20000 349.67 12317.24 uses POE::Loop::Event	2657	POE 20000 341.54 12086.32 uses POE::Loop::Event
1550		2658
1551	=head3 Discussion	2659	=head3 Discussion
1552		2660
1553	This benchmark I<does> measure scalability and overall performance of the	2661	This benchmark I<does> measure scalability and overall performance of the
1554	particular event loop.	2662	particular event loop.
…		…
1556	EV is again fastest. Since it is using epoll on my system, the setup time	2664	EV is again fastest. Since it is using epoll on my system, the setup time
1557	is relatively high, though.	2665	is relatively high, though.
1558		2666
1559	Perl surprisingly comes second. It is much faster than the C-based event	2667	Perl surprisingly comes second. It is much faster than the C-based event
1560	loops Event and Glib.	2668	loops Event and Glib.
		2669
		2670	IO::Async performs very well when using its epoll backend, and still quite
		2671	good compared to Glib when using its pure perl backend.
1561		2672
1562	Event suffers from high setup time as well (look at its code and you will	2673	Event suffers from high setup time as well (look at its code and you will
1563	understand why). Callback invocation also has a high overhead compared to	2674	understand why). Callback invocation also has a high overhead compared to
1564	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2675	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565	uses select or poll in basically all documented configurations.	2676	uses select or poll in basically all documented configurations.
…		…
1628	=item * C-based event loops perform very well with small number of	2739	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	2740	watchers, as the management overhead dominates.
1630		2741
1631	=back	2742	=back
1632		2743
		2744	=head2 THE IO::Lambda BENCHMARK
		2745
		2746	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2747	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2748	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2749	shouldn't come as a surprise to anybody). As such, the benchmark is
		2750	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2751	very optimal. But how would AnyEvent compare when used without the extra
		2752	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2753
		2754	The benchmark itself creates an echo-server, and then, for 500 times,
		2755	connects to the echo server, sends a line, waits for the reply, and then
		2756	creates the next connection. This is a rather bad benchmark, as it doesn't
		2757	test the efficiency of the framework or much non-blocking I/O, but it is a
		2758	benchmark nevertheless.
		2759
		2760	name runtime
		2761	Lambda/select 0.330 sec
		2762	+ optimized 0.122 sec
		2763	Lambda/AnyEvent 0.327 sec
		2764	+ optimized 0.138 sec
		2765	Raw sockets/select 0.077 sec
		2766	POE/select, components 0.662 sec
		2767	POE/select, raw sockets 0.226 sec
		2768	POE/select, optimized 0.404 sec
		2769
		2770	AnyEvent/select/nb 0.085 sec
		2771	AnyEvent/EV/nb 0.068 sec
		2772	+state machine 0.134 sec
		2773
		2774	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2775	benchmarks actually make blocking connects and use 100% blocking I/O,
		2776	defeating the purpose of an event-based solution. All of the newly
		2777	written AnyEvent benchmarks use 100% non-blocking connects (using
		2778	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2779	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2780	generally require a lot more bookkeeping and event handling than blocking
		2781	connects (which involve a single syscall only).
		2782
		2783	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2784	offers similar expressive power as POE and IO::Lambda, using conventional
		2785	Perl syntax. This means that both the echo server and the client are 100%
		2786	non-blocking, further placing it at a disadvantage.
		2787
		2788	As you can see, the AnyEvent + EV combination even beats the
		2789	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2790	backend easily beats IO::Lambda and POE.
		2791
		2792	And even the 100% non-blocking version written using the high-level (and
		2793	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2794	higher level ("unoptimised") abstractions by a large margin, even though
		2795	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2796
		2797	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2798	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2799	part of the IO::Lambda distribution and were used without any changes.
		2800
		2801
		2802	=head1 SIGNALS
		2803
		2804	AnyEvent currently installs handlers for these signals:
		2805
		2806	=over 4
		2807
		2808	=item SIGCHLD
		2809
		2810	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2811	emulation for event loops that do not support them natively. Also, some
		2812	event loops install a similar handler.
		2813
		2814	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2815	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2816
		2817	=item SIGPIPE
		2818
		2819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2820	when AnyEvent gets loaded.
		2821
		2822	The rationale for this is that AnyEvent users usually do not really depend
		2823	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2824	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2825	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2826	some random socket.
		2827
		2828	The rationale for installing a no-op handler as opposed to ignoring it is
		2829	that this way, the handler will be restored to defaults on exec.
		2830
		2831	Feel free to install your own handler, or reset it to defaults.
		2832
		2833	=back
		2834
		2835	=cut
		2836
		2837	undef $SIG{CHLD}
		2838	if $SIG{CHLD} eq 'IGNORE';
		2839
		2840	$SIG{PIPE} = sub { }
		2841	unless defined $SIG{PIPE};
		2842
		2843	=head1 RECOMMENDED/OPTIONAL MODULES
		2844
		2845	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2846	its built-in modules) are required to use it.
		2847
		2848	That does not mean that AnyEvent won't take advantage of some additional
		2849	modules if they are installed.
		2850
		2851	This section explains which additional modules will be used, and how they
		2852	affect AnyEvent's operation.
		2853
		2854	=over 4
		2855
		2856	=item L<Async::Interrupt>
		2857
		2858	This slightly arcane module is used to implement fast signal handling: To
		2859	my knowledge, there is no way to do completely race-free and quick
		2860	signal handling in pure perl. To ensure that signals still get
		2861	delivered, AnyEvent will start an interval timer to wake up perl (and
		2862	catch the signals) with some delay (default is 10 seconds, look for
		2863	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2864
		2865	If this module is available, then it will be used to implement signal
		2866	catching, which means that signals will not be delayed, and the event loop
		2867	will not be interrupted regularly, which is more efficient (and good for
		2868	battery life on laptops).
		2869
		2870	This affects not just the pure-perl event loop, but also other event loops
		2871	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2872
		2873	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2874	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2875	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2876	does nothing for those backends.
		2877
		2878	=item L<EV>
		2879
		2880	This module isn't really "optional", as it is simply one of the backend
		2881	event loops that AnyEvent can use. However, it is simply the best event
		2882	loop available in terms of features, speed and stability: It supports
		2883	the AnyEvent API optimally, implements all the watcher types in XS, does
		2884	automatic timer adjustments even when no monotonic clock is available,
		2885	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2886	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2887	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2888
		2889	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2890	then this module will do nothing for you.
		2891
		2892	=item L<Guard>
		2893
		2894	The guard module, when used, will be used to implement
		2895	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2896	lot less memory), but otherwise doesn't affect guard operation much. It is
		2897	purely used for performance.
		2898
		2899	=item L<JSON> and L<JSON::XS>
		2900
		2901	One of these modules is required when you want to read or write JSON data
		2902	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2903	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2904
		2905	=item L<Net::SSLeay>
		2906
		2907	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2908	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2909	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2910
		2911	=item L<Time::HiRes>
		2912
		2913	This module is part of perl since release 5.008. It will be used when the
		2914	chosen event library does not come with a timing source of its own. The
		2915	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2916	try to use a monotonic clock for timing stability.
		2917
		2918	=back
		2919
1633		2920
1634	=head1 FORK	2921	=head1 FORK
1635		2922
1636	Most event libraries are not fork-safe. The ones who are usually are	2923	Most event libraries are not fork-safe. The ones who are usually are
1637	because they rely on inefficient but fork-safe C<select> or C<poll>	2924	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1638	calls. Only L<EV> is fully fork-aware.	2925	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2926	are usually badly thought-out hacks that are incompatible with fork in
		2927	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2928	continue event-processing in both parent and child (or both, if you know
		2929	what you are doing).
		2930
		2931	This means that, in general, you cannot fork and do event processing in
		2932	the child if the event library was initialised before the fork (which
		2933	usually happens when the first AnyEvent watcher is created, or the library
		2934	is loaded).
1639		2935
1640	If you have to fork, you must either do so I<before> creating your first	2936	If you have to fork, you must either do so I<before> creating your first
1641	watcher OR you must not use AnyEvent at all in the child.	2937	watcher OR you must not use AnyEvent at all in the child OR you must do
		2938	something completely out of the scope of AnyEvent.
		2939
		2940	The problem of doing event processing in the parent I<and> the child
		2941	is much more complicated: even for backends that I<are> fork-aware or
		2942	fork-safe, their behaviour is not usually what you want: fork clones all
		2943	watchers, that means all timers, I/O watchers etc. are active in both
		2944	parent and child, which is almost never what you want. USing C<exec>
		2945	to start worker children from some kind of manage rprocess is usually
		2946	preferred, because it is much easier and cleaner, at the expense of having
		2947	to have another binary.
1642		2948
1643		2949
1644	=head1 SECURITY CONSIDERATIONS	2950	=head1 SECURITY CONSIDERATIONS
1645		2951
1646	AnyEvent can be forced to load any event model via	2952	AnyEvent can be forced to load any event model via
…		…
1651	specified in the variable.	2957	specified in the variable.
1652		2958
1653	You can make AnyEvent completely ignore this variable by deleting it	2959	You can make AnyEvent completely ignore this variable by deleting it
1654	before the first watcher gets created, e.g. with a C<BEGIN> block:	2960	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2961
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2962	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2963
1658	use AnyEvent;	2964	use AnyEvent;
1659		2965
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2966	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661	be used to probe what backend is used and gain other information (which is	2967	be used to probe what backend is used and gain other information (which is
1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2968	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2969	$ENV{PERL_ANYEVENT_STRICT}.
		2970
		2971	Note that AnyEvent will remove I<all> environment variables starting with
		2972	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2973	enabled.
		2974
		2975
		2976	=head1 BUGS
		2977
		2978	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2979	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2980	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2981	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2982	pronounced).
1663		2983
1664		2984
1665	=head1 SEE ALSO	2985	=head1 SEE ALSO
1666		2986
1667	Utility functions: L<AnyEvent::Util>.	2987	Tutorial/Introduction: L<AnyEvent::Intro>.
1668		2988
1669	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2989	FAQ: L<AnyEvent::FAQ>.
1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2990
		2991	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2992	(simply logging).
		2993
		2994	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2995	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2996
		2997	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2998	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2999	L<Qt>, L<POE>, L<FLTK>.
1671		3000
1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	3001	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	3002	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	3003	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		3004	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1675	L<AnyEvent::Impl::POE>.	3005	L<AnyEvent::Impl::FLTK>.
1676		3006
1677	Non-blocking file handles, sockets, TCP clients and	3007	Non-blocking handles, pipes, stream sockets, TCP clients and
1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	3008	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1679		3009
1680	Asynchronous DNS: L<AnyEvent::DNS>.	3010	Asynchronous DNS: L<AnyEvent::DNS>.
1681		3011
1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	3012	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1683		3013
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	3014	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		3015	L<AnyEvent::HTTP>.
1685		3016
1686		3017
1687	=head1 AUTHOR	3018	=head1 AUTHOR
1688		3019
1689	Marc Lehmann <schmorp@schmorp.de>	3020	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	3021	http://home.schmorp.de/
1691		3022
1692	=cut	3023	=cut
1693		3024
1694	1	3025	1
1695		3026

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