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Revision 1.139 by root, Mon May 26 06:04:38 2008 UTC vs.
Revision 1.360 by root, Sat Aug 13 22:44:05 2011 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# if you prefer function calls, look at the AE manpage for
		13	# an alternative API.
		14
		15	# file handle or descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		17
		18	# one-shot or repeating timers
		19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
		21
		22	print AnyEvent->now; # prints current event loop time
		23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		24
		25	# POSIX signal
		26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		27
		28	# child process exit
		29	my $w = AnyEvent->child (pid => $pid, cb => sub {
		30	my ($pid, $status) = @_;
12	...	31	...
13	});	32	});
14		33
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	34	# called when event loop idle (if applicable)
16	...	35	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		36
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
		40	# use a condvar in callback mode:
		41	$w->cb (sub { $_[0]->recv });
		42
		43	=head1 INTRODUCTION/TUTORIAL
		44
		45	This manpage is mainly a reference manual. If you are interested
		46	in a tutorial or some gentle introduction, have a look at the
		47	L<AnyEvent::Intro> manpage.
		48
		49	=head1 SUPPORT
		50
		51	An FAQ document is available as L<AnyEvent::FAQ>.
		52
		53	There also is a mailinglist for discussing all things AnyEvent, and an IRC
		54	channel, too.
		55
		56	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		57	Repository>, at L<http://anyevent.schmorp.de>, for more info.
22		58
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		60
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	61	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
27		63
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	64	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	65	policy> and AnyEvent is I<small and efficient>.
30		66
31	First and foremost, I<AnyEvent is not an event model> itself, it only	67	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	68	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	69	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	70	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	71	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	72	cannot change this, but it can hide the differences between those event
		73	loops.
37		74
38	The goal of AnyEvent is to offer module authors the ability to do event	75	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	76	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	77	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	78	module users into the same thing by forcing them to use the same event
42	model you use.	79	model you use.
43		80
44	For modules like POE or IO::Async (which is a total misnomer as it is	81	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	82	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	83	like joining a cult: After you join, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	84	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	85	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	86	module are I<also> forced to use the same event loop you use.
50		87
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	89	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	90	with the rest: POE + EV? No go. Tk + Event? No go. Again: if your module
54	your module uses one of those, every user of your module has to use it,	91	uses one of those, every user of your module has to use it, too. But if
55	too. But if your module uses AnyEvent, it works transparently with all	92	your module uses AnyEvent, it works transparently with all event models it
56	event models it supports (including stuff like POE and IO::Async, as long	93	supports (including stuff like IO::Async, as long as those use one of the
57	as those use one of the supported event loops. It is trivial to add new	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
58	event loops to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
59		96
60	In addition to being free of having to use I<the one and only true event	97	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	98	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	99	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	100	follow. AnyEvent, on the other hand, is lean and to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	101	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	102	technically possible.
66		103
		104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		105	of useful functionality, such as an asynchronous DNS resolver, 100%
		106	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		107	such as Windows) and lots of real-world knowledge and workarounds for
		108	platform bugs and differences.
		109
67	Of course, if you want lots of policy (this can arguably be somewhat	110	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	111	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	112	model, you should I<not> use this module.
70		113
71	=head1 DESCRIPTION	114	=head1 DESCRIPTION
72		115
73	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
74	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
75	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
76	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
77		120
78	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>
79	module.	122	module.
80		123
81	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
82	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
83	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
84	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
85	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
86	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
87	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
88	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
89	found, AnyEvent will fall back to a pure-perl event loop, which is not
90	very efficient, but should work everywhere.
91		132
92	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
93	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
94	that model the default. For example:	135	that model the default. For example:
95		136
…		…
97	use AnyEvent;	138	use AnyEvent;
98		139
99	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
100		141
101	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
102	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,
103	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
104		146
105	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
106	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
107	explicitly.	149	availability of that event loop :)
108		150
109	=head1 WATCHERS	151	=head1 WATCHERS
110		152
111	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
112	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
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	160	is in control).
119		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
120	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
121	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
122	to it).	170	to it).
123		171
124	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.
125		173
126	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		176
129	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
130		178
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
133	undef $w;	181	undef $w;
134	});	182	});
135		183
136	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,
137	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
138	declared.	186	declared.
139		187
140	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
141		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
142	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
143	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
144		198
145	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
146	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
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
148	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.
149	becomes ready.
150		210
151	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
154		214
155	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.
156	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
157	underlying file descriptor.	217	underlying file descriptor.
158		218
159	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
160	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
161	handles.	221	handles.
162		222
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	226	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	227	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	228	warn "read: $input\n";
169	undef $w;	229	undef $w;
170	});	230	});
171		231
172	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
173		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
174	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 >>
175	method with the following mandatory arguments:	243	method with the following mandatory arguments:
176		244
177	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
178	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
…		…
180		248
181	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
184		252
185	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
186	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
187	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.
188		258
189	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.
190		262
191	# fire an event after 7.7 seconds	263	Example: fire an event after 7.7 seconds.
		264
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	266	warn "timeout\n";
194	});	267	});
195		268
196	# to cancel the timer:	269	# to cancel the timer:
197	undef $w;	270	undef $w;
198		271
199	Example 2:
200
201	# 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.
202	my $w;
203		273
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	274	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		275	warn "timeout\n";
207	};	276	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		277
212	=head3 TIMING ISSUES	278	=head3 TIMING ISSUES
213		279
214	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
215	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
…		…
217		283
218	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
219	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
220	"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
221	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
222	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.
223		289
224	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
225	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
226	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)
227	timers.	293	timers.
228		294
229	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	296	AnyEvent API.
231		297
		298	AnyEvent has two additional methods that return the "current time":
		299
		300	=over 4
		301
		302	=item AnyEvent->time
		303
		304	This returns the "current wallclock time" as a fractional number of
		305	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		306	return, and the result is guaranteed to be compatible with those).
		307
		308	It progresses independently of any event loop processing, i.e. each call
		309	will check the system clock, which usually gets updated frequently.
		310
		311	=item AnyEvent->now
		312
		313	This also returns the "current wallclock time", but unlike C<time>, above,
		314	this value might change only once per event loop iteration, depending on
		315	the event loop (most return the same time as C<time>, above). This is the
		316	time that AnyEvent's timers get scheduled against.
		317
		318	I<In almost all cases (in all cases if you don't care), this is the
		319	function to call when you want to know the current time.>
		320
		321	This function is also often faster then C<< AnyEvent->time >>, and
		322	thus the preferred method if you want some timestamp (for example,
		323	L<AnyEvent::Handle> uses this to update its activity timeouts).
		324
		325	The rest of this section is only of relevance if you try to be very exact
		326	with your timing; you can skip it without a bad conscience.
		327
		328	For a practical example of when these times differ, consider L<Event::Lib>
		329	and L<EV> and the following set-up:
		330
		331	The event loop is running and has just invoked one of your callbacks at
		332	time=500 (assume no other callbacks delay processing). In your callback,
		333	you wait a second by executing C<sleep 1> (blocking the process for a
		334	second) and then (at time=501) you create a relative timer that fires
		335	after three seconds.
		336
		337	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		338	both return C<501>, because that is the current time, and the timer will
		339	be scheduled to fire at time=504 (C<501> + C<3>).
		340
		341	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		342	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		343	last event processing phase started. With L<EV>, your timer gets scheduled
		344	to run at time=503 (C<500> + C<3>).
		345
		346	In one sense, L<Event::Lib> is more exact, as it uses the current time
		347	regardless of any delays introduced by event processing. However, most
		348	callbacks do not expect large delays in processing, so this causes a
		349	higher drift (and a lot more system calls to get the current time).
		350
		351	In another sense, L<EV> is more exact, as your timer will be scheduled at
		352	the same time, regardless of how long event processing actually took.
		353
		354	In either case, if you care (and in most cases, you don't), then you
		355	can get whatever behaviour you want with any event loop, by taking the
		356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		357	account.
		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
		381	=back
		382
232	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
233		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		386
234	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
235	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
236	be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
237		390
238	Although the callback might get passed parameters, their value and	391	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	392	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	393	callbacks cannot use arguments passed to signal watcher callbacks.
241		394
…		…
243	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
246		399
247	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
248	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
249		403
250	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
251	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
252		407
253	Example: exit on SIGINT	408	Example: exit on SIGINT
254		409
255	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
256		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		437	variable can be changed only before the first signal watcher is created,
		438	and should be left alone otherwise. This variable determines how often
		439	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		440	will cause fewer spurious wake-ups, which is better for power and CPU
		441	saving.
		442
		443	All these problems can be avoided by installing the optional
		444	L<Async::Interrupt> module, which works with most event loops. It will not
		445	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		446	(and not with L<POE> currently, as POE does its own workaround with
		447	one-second latency). For those, you just have to suffer the delays.
		448
257	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
258		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
259	You can also watch on a child process exit and catch its exit status.	453	You can also watch for a child process exit and catch its exit status.
260		454
261	The child process is specified by the C<pid> argument (if set to C<0>, it	455	The child process is specified by the C<pid> argument (on some backends,
262	watches for any child process exit). The watcher will trigger as often	456	using C<0> watches for any child process exit, on others this will
263	as status change for the child are received. This works by installing a	457	croak). The watcher will be triggered only when the child process has
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	458	finished and an exit status is available, not on any trace events
265	and exit status (as returned by waitpid), so unlike other watcher types,	459	(stopped/continued).
266	you I<can> rely on child watcher callback arguments.	460
		461	The callback will be called with the pid and exit status (as returned by
		462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		463	callback arguments.
		464
		465	This watcher type works by installing a signal handler for C<SIGCHLD>,
		466	and since it cannot be shared, nothing else should use SIGCHLD or reap
		467	random child processes (waiting for specific child processes, e.g. inside
		468	C<system>, is just fine).
267		469
268	There is a slight catch to child watchers, however: you usually start them	470	There is a slight catch to child watchers, however: you usually start them
269	I<after> the child process was created, and this means the process could	471	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
271		473
272	Not all event models handle this correctly (POE doesn't), but even for	474	Not all event models handle this correctly (neither POE nor IO::Async do,
		475	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	476	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	477	the process exits (i.e. before you fork in the first place). AnyEvent's
		478	pure perl event loop handles all cases correctly regardless of when you
		479	start the watcher.
275		480
276	This means you cannot create a child watcher as the very first thing in an	481	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	482	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	483	watcher before you C<fork> the child (alternatively, you can call
		484	C<AnyEvent::detect>).
		485
		486	As most event loops do not support waiting for child events, they will be
		487	emulated by AnyEvent in most cases, in which case the latency and race
		488	problems mentioned in the description of signal watchers apply.
279		489
280	Example: fork a process and wait for it	490	Example: fork a process and wait for it
281		491
282	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
283		493
284	my $pid = fork or exit 5;	494	my $pid = fork or exit 5;
285		495
286	my $w = AnyEvent->child (	496	my $w = AnyEvent->child (
287	pid => $pid,	497	pid => $pid,
288	cb => sub {	498	cb => sub {
289	my ($pid, $status) = @_;	499	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	500	warn "pid $pid exited with status $status";
291	$done->send;	501	$done->send;
292	},	502	},
293	);	503	);
294		504
295	# do something else, then wait for process exit	505	# do something else, then wait for process exit
296	$done->recv;	506	$done->recv;
		507
		508	=head2 IDLE WATCHERS
		509
		510	$w = AnyEvent->idle (cb => <callback>);
		511
		512	This will repeatedly invoke the callback after the process becomes idle,
		513	until either the watcher is destroyed or new events have been detected.
		514
		515	Idle watchers are useful when there is a need to do something, but it
		516	is not so important (or wise) to do it instantly. The callback will be
		517	invoked only when there is "nothing better to do", which is usually
		518	defined as "all outstanding events have been handled and no new events
		519	have been detected". That means that idle watchers ideally get invoked
		520	when the event loop has just polled for new events but none have been
		521	detected. Instead of blocking to wait for more events, the idle watchers
		522	will be invoked.
		523
		524	Unfortunately, most event loops do not really support idle watchers (only
		525	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		526	will simply call the callback "from time to time".
		527
		528	Example: read lines from STDIN, but only process them when the
		529	program is otherwise idle:
		530
		531	my @lines; # read data
		532	my $idle_w;
		533	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		534	push @lines, scalar <STDIN>;
		535
		536	# start an idle watcher, if not already done
		537	$idle_w ||= AnyEvent->idle (cb => sub {
		538	# handle only one line, when there are lines left
		539	if (my $line = shift @lines) {
		540	print "handled when idle: $line";
		541	} else {
		542	# otherwise disable the idle watcher again
		543	undef $idle_w;
		544	}
		545	});
		546	});
297		547
298	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
299		554
300	If you are familiar with some event loops you will know that all of them	555	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	556	require you to run some blocking "loop", "run" or similar function that
302	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
303		558
304	AnyEvent is different, it expects somebody else to run the event loop and	559	AnyEvent is slightly different: it expects somebody else to run the event
305	will only block when necessary (usually when told by the user).	560	loop and will only block when necessary (usually when told by the user).
306		561
307	The instrument to do that is called a "condition variable", so called	562	The tool to do that is called a "condition variable", so called because
308	because they represent a condition that must become true.	563	they represent a condition that must become true.
		564
		565	Now is probably a good time to look at the examples further below.
309		566
310	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
312	C<cb>, which specifies a callback to be called when the condition variable	569	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	570	becomes true, with the condition variable as the first argument (but not
		571	the results).
314		572
315	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	574	by calling the C<send> method (or calling the condition variable as if it
317	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
318	->send >> method).	576	->send >> method).
319		577
320	Condition variables are similar to callbacks, except that you can	578	Since condition variables are the most complex part of the AnyEvent API, here are
321	optionally wait for them. They can also be called merge points - points	579	some different mental models of what they are - pick the ones you can connect to:
322	in time where multiple outstanding events have been processed. And yet	580
323	another way to call them is transactions - each condition variable can be	581	=over 4
324	used to represent a transaction, which finishes at some point and delivers	582
325	a result.	583	=item * Condition variables are like callbacks - you can call them (and pass them instead
		584	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		585
		586	=item * Condition variables are signals - one side can emit or send them,
		587	the other side can wait for them, or install a handler that is called when
		588	the signal fires.
		589
		590	=item * Condition variables are like "Merge Points" - points in your program
		591	where you merge multiple independent results/control flows into one.
		592
		593	=item * Condition variables represent a transaction - functions that start
		594	some kind of transaction can return them, leaving the caller the choice
		595	between waiting in a blocking fashion, or setting a callback.
		596
		597	=item * Condition variables represent future values, or promises to deliver
		598	some result, long before the result is available.
		599
		600	=back
326		601
327	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	603	for example, if you write a module that does asynchronous http requests,
329	then a condition variable would be the ideal candidate to signal the	604	then a condition variable would be the ideal candidate to signal the
330	availability of results. The user can either act when the callback is	605	availability of results. The user can either act when the callback is
…		…
343		618
344	Condition variables are represented by hash refs in perl, and the keys	619	Condition variables are represented by hash refs in perl, and the keys
345	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	620	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
346	easy (it is often useful to build your own transaction class on top of	621	easy (it is often useful to build your own transaction class on top of
347	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	622	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
349		624
350	There are two "sides" to a condition variable - the "producer side" which	625	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the send to occur.	627	for the send to occur.
353		628
354	Example: wait for a timer.	629	Example: wait for a timer.
355		630
356	# wait till the result is ready	631	# condition: "wait till the timer is fired"
357	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
358		633
359	# do something such as adding a timer	634	# create the timer - we could wait for, say
360	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
361	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
362	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
364	after => 1,	639	after => 1,
365	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
366	);	641	);
367		642
368	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
369	# calls send	644	# calls ->send
370	$result_ready->recv;	645	$timer_fired->recv;
371		646
372	Example: wait for a timer, but take advantage of the fact that	647	Example: wait for a timer, but take advantage of the fact that condition
373	condition variables are also code references.	648	variables are also callable directly.
374		649
375	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
376	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
377	$done->recv;	652	$done->recv;
		653
		654	Example: Imagine an API that returns a condvar and doesn't support
		655	callbacks. This is how you make a synchronous call, for example from
		656	the main program:
		657
		658	use AnyEvent::CouchDB;
		659
		660	...
		661
		662	my @info = $couchdb->info->recv;
		663
		664	And this is how you would just set a callback to be called whenever the
		665	results are available:
		666
		667	$couchdb->info->cb (sub {
		668	my @info = $_[0]->recv;
		669	});
378		670
379	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
380		672
381	These methods should only be used by the producing side, i.e. the	673	These methods should only be used by the producing side, i.e. the
382	code/module that eventually sends the signal. Note that it is also	674	code/module that eventually sends the signal. Note that it is also
…		…
395	immediately from within send.	687	immediately from within send.
396		688
397	Any arguments passed to the C<send> call will be returned by all	689	Any arguments passed to the C<send> call will be returned by all
398	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
399		691
400	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
401	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
402	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
403	overloading, so as tempting as it may be, passing a condition variable
404	instead of a callback does not work. Both the pure perl and EV loops
405	support overloading, however, as well as all functions that use perl to
406	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
407	example).
408		695
409	=item $cv->croak ($error)	696	=item $cv->croak ($error)
410		697
411	Similar to send, but causes all call's to C<< ->recv >> to invoke	698	Similar to send, but causes all calls to C<< ->recv >> to invoke
412	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
413		700
414	This can be used to signal any errors to the condition variable	701	This can be used to signal any errors to the condition variable
415	user/consumer.	702	user/consumer. Doing it this way instead of calling C<croak> directly
		703	delays the error detection, but has the overwhelming advantage that it
		704	diagnoses the error at the place where the result is expected, and not
		705	deep in some event callback with no connection to the actual code causing
		706	the problem.
416		707
417	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
418		709
419	=item $cv->end	710	=item $cv->end
420
421	These two methods are EXPERIMENTAL and MIGHT CHANGE.
422		711
423	These two methods can be used to combine many transactions/events into	712	These two methods can be used to combine many transactions/events into
424	one. For example, a function that pings many hosts in parallel might want	713	one. For example, a function that pings many hosts in parallel might want
425	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
426		715
427	Every call to C<< ->begin >> will increment a counter, and every call to	716	Every call to C<< ->begin >> will increment a counter, and every call to
428	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	717	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
429	>>, the (last) callback passed to C<begin> will be executed. That callback	718	>>, the (last) callback passed to C<begin> will be executed, passing the
430	is I<supposed> to call C<< ->send >>, but that is not required. If no	719	condvar as first argument. That callback is I<supposed> to call C<< ->send
431	callback was set, C<send> will be called without any arguments.	720	>>, but that is not required. If no group callback was set, C<send> will
		721	be called without any arguments.
432		722
433	Let's clarify this with the ping example:	723	You can think of C<< $cv->send >> giving you an OR condition (one call
		724	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		725	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		726
		727	Let's start with a simple example: you have two I/O watchers (for example,
		728	STDOUT and STDERR for a program), and you want to wait for both streams to
		729	close before activating a condvar:
434		730
435	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
436		732
		733	$cv->begin; # first watcher
		734	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		735	defined sysread $fh1, my $buf, 4096
		736	or $cv->end;
		737	});
		738
		739	$cv->begin; # second watcher
		740	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		741	defined sysread $fh2, my $buf, 4096
		742	or $cv->end;
		743	});
		744
		745	$cv->recv;
		746
		747	This works because for every event source (EOF on file handle), there is
		748	one call to C<begin>, so the condvar waits for all calls to C<end> before
		749	sending.
		750
		751	The ping example mentioned above is slightly more complicated, as the
		752	there are results to be passwd back, and the number of tasks that are
		753	begun can potentially be zero:
		754
		755	my $cv = AnyEvent->condvar;
		756
437	my %result;	757	my %result;
438	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
439		759
440	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
441	$cv->begin;	761	$cv->begin;
442	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
443	$result{$host} = ...;	763	$result{$host} = ...;
…		…
458	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
459	to be called once the counter reaches C<0>, and second, it ensures that	779	to be called once the counter reaches C<0>, and second, it ensures that
460	C<send> is called even when C<no> hosts are being pinged (the loop	780	C<send> is called even when C<no> hosts are being pinged (the loop
461	doesn't execute once).	781	doesn't execute once).
462		782
463	This is the general pattern when you "fan out" into multiple subrequests:	783	This is the general pattern when you "fan out" into multiple (but
464	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	784	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
465	is called at least once, and then, for each subrequest you start, call	785	the callback and ensure C<end> is called at least once, and then, for each
466	C<begin> and for each subrequest you finish, call C<end>.	786	subrequest you start, call C<begin> and for each subrequest you finish,
		787	call C<end>.
467		788
468	=back	789	=back
469		790
470	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
471		792
…		…
475	=over 4	796	=over 4
476		797
477	=item $cv->recv	798	=item $cv->recv
478		799
479	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
480	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
481	normally.	802	normally.
482		803
483	You can only wait once on a condition - additional calls are valid but	804	You can only wait once on a condition - additional calls are valid but
484	will return immediately.	805	will return immediately.
485		806
…		…
487	function will call C<croak>.	808	function will call C<croak>.
488		809
489	In list context, all parameters passed to C<send> will be returned,	810	In list context, all parameters passed to C<send> will be returned,
490	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
491		812
		813	Note that doing a blocking wait in a callback is not supported by any
		814	event loop, that is, recursive invocation of a blocking C<< ->recv
		815	>> is not allowed, and the C<recv> call will C<croak> if such a
		816	condition is detected. This condition can be slightly loosened by using
		817	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		818	any thread that doesn't run the event loop itself.
		819
492	Not all event models support a blocking wait - some die in that case	820	Not all event models support a blocking wait - some die in that case
493	(programs might want to do that to stay interactive), so I<if you are	821	(programs might want to do that to stay interactive), so I<if you are
494	using this from a module, never require a blocking wait>, but let the	822	using this from a module, never require a blocking wait>. Instead, let the
495	caller decide whether the call will block or not (for example, by coupling	823	caller decide whether the call will block or not (for example, by coupling
496	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
497	callbacks so the caller knows that getting the result will not block,	825	callbacks so the caller knows that getting the result will not block,
498	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
499		827
500	Another reason I<never> to C<< ->recv >> in a module is that you cannot
501	sensibly have two C<< ->recv >>'s in parallel, as that would require
502	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
503	can supply.
504
505	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
506	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
507	versions and also integrates coroutines into AnyEvent, making blocking
508	C<< ->recv >> calls perfectly safe as long as they are done from another
509	coroutine (one that doesn't run the event loop).
510
511	You can ensure that C<< -recv >> never blocks by setting a callback and	828	You can ensure that C<< ->recv >> never blocks by setting a callback and
512	only calling C<< ->recv >> from within that callback (or at a later	829	only calling C<< ->recv >> from within that callback (or at a later
513	time). This will work even when the event loop does not support blocking	830	time). This will work even when the event loop does not support blocking
514	waits otherwise.	831	waits otherwise.
515		832
516	=item $bool = $cv->ready	833	=item $bool = $cv->ready
517		834
518	Returns true when the condition is "true", i.e. whether C<send> or	835	Returns true when the condition is "true", i.e. whether C<send> or
519	C<croak> have been called.	836	C<croak> have been called.
520		837
521	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
522		839
523	This is a mutator function that returns the callback set and optionally	840	This is a mutator function that returns the callback set and optionally
524	replaces it before doing so.	841	replaces it before doing so.
525		842
526	The callback will be called when the condition becomes "true", i.e. when	843	The callback will be called when the condition becomes "true", i.e. when
527	C<send> or C<croak> are called. Calling C<recv> inside the callback	844	C<send> or C<croak> are called, with the only argument being the
		845	condition variable itself. If the condition is already true, the
		846	callback is called immediately when it is set. Calling C<recv> inside
528	or at any later time is guaranteed not to block.	847	the callback or at any later time is guaranteed not to block.
529		848
530	=back	849	=back
531		850
		851	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		852
		853	The available backend classes are (every class has its own manpage):
		854
		855	=over 4
		856
		857	=item Backends that are autoprobed when no other event loop can be found.
		858
		859	EV is the preferred backend when no other event loop seems to be in
		860	use. If EV is not installed, then AnyEvent will fall back to its own
		861	pure-perl implementation, which is available everywhere as it comes with
		862	AnyEvent itself.
		863
		864	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		865	AnyEvent::Impl::Perl pure-perl AnyEvent::Loop, fast and portable.
		866
		867	=item Backends that are transparently being picked up when they are used.
		868
		869	These will be used if they are already loaded when the first watcher
		870	is created, in which case it is assumed that the application is using
		871	them. This means that AnyEvent will automatically pick the right backend
		872	when the main program loads an event module before anything starts to
		873	create watchers. Nothing special needs to be done by the main program.
		874
		875	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		876	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		877	AnyEvent::Impl::Tk based on Tk, very broken.
		878	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		879	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		880	AnyEvent::Impl::Irssi used when running within irssi.
		881	AnyEvent::Impl::IOAsync based on IO::Async.
		882	AnyEvent::Impl::Cocoa based on Cocoa::EventLoop.
		883	AnyEvent::Impl::FLTK2 based on FLTK (fltk 2 binding).
		884
		885	=item Backends with special needs.
		886
		887	Qt requires the Qt::Application to be instantiated first, but will
		888	otherwise be picked up automatically. As long as the main program
		889	instantiates the application before any AnyEvent watchers are created,
		890	everything should just work.
		891
		892	AnyEvent::Impl::Qt based on Qt.
		893
		894	=item Event loops that are indirectly supported via other backends.
		895
		896	Some event loops can be supported via other modules:
		897
		898	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		899
		900	B<WxWidgets> has no support for watching file handles. However, you can
		901	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		902	polls 20 times per second, which was considered to be too horrible to even
		903	consider for AnyEvent.
		904
		905	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		906	backend, so it can be supported through POE.
		907
		908	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		909	load L<POE> when detecting them, in the hope that POE will pick them up,
		910	in which case everything will be automatic.
		911
		912	=back
		913
532	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
533		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
534	=over 4	919	=over 4
535		920
536	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
537		922
538	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
539	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
540	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
541	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
542	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
543		930	will be C<urxvt::anyevent>).
544	The known classes so far are:
545
546	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
547	AnyEvent::Impl::Event based on Event, second best choice.
548	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
549	AnyEvent::Impl::Glib based on Glib, third-best choice.
550	AnyEvent::Impl::Tk based on Tk, very bad choice.
551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
553	AnyEvent::Impl::POE based on POE, not generic enough for full support.
554
555	There is no support for WxWidgets, as WxWidgets has no support for
556	watching file handles. However, you can use WxWidgets through the
557	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
558	second, which was considered to be too horrible to even consider for
559	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
560	it's adaptor.
561
562	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
563	autodetecting them.
564		931
565	=item AnyEvent::detect	932	=item AnyEvent::detect
566		933
567	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
568	if necessary. You should only call this function right before you would	935	if necessary. You should only call this function right before you would
569	have created an AnyEvent watcher anyway, that is, as late as possible at	936	have created an AnyEvent watcher anyway, that is, as late as possible at
570	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
571		945
572	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
573		947
574	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
575	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
576		961
577	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
578	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
579	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
580		982
581	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
582		984
583	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
584	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
585	the event loop has been chosen.	987	after the event loop has been chosen.
586		988
587	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
588	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
589	and the array will be ignored.	991	array will be ignored.
590		992
591	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
592		1053
593	=back	1054	=back
594		1055
595	=head1 WHAT TO DO IN A MODULE	1056	=head1 WHAT TO DO IN A MODULE
596		1057
…		…
607	because it will stall the whole program, and the whole point of using	1068	because it will stall the whole program, and the whole point of using
608	events is to stay interactive.	1069	events is to stay interactive.
609		1070
610	It is fine, however, to call C<< ->recv >> when the user of your module	1071	It is fine, however, to call C<< ->recv >> when the user of your module
611	requests it (i.e. if you create a http request object ad have a method	1072	requests it (i.e. if you create a http request object ad have a method
612	called C<results> that returns the results, it should call C<< ->recv >>	1073	called C<results> that returns the results, it may call C<< ->recv >>
613	freely, as the user of your module knows what she is doing. always).	1074	freely, as the user of your module knows what she is doing. Always).
614		1075
615	=head1 WHAT TO DO IN THE MAIN PROGRAM	1076	=head1 WHAT TO DO IN THE MAIN PROGRAM
616		1077
617	There will always be a single main program - the only place that should	1078	There will always be a single main program - the only place that should
618	dictate which event model to use.	1079	dictate which event model to use.
619		1080
620	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1081	If the program is not event-based, it need not do anything special, even
621	do anything special (it does not need to be event-based) and let AnyEvent	1082	when it depends on a module that uses an AnyEvent. If the program itself
622	decide which implementation to chose if some module relies on it.	1083	uses AnyEvent, but does not care which event loop is used, all it needs
		1084	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1085	available loop implementation.
623		1086
624	If the main program relies on a specific event model - for example, in	1087	If the main program relies on a specific event model - for example, in
625	Gtk2 programs you have to rely on the Glib module - you should load the	1088	Gtk2 programs you have to rely on the Glib module - you should load the
626	event module before loading AnyEvent or any module that uses it: generally	1089	event module before loading AnyEvent or any module that uses it: generally
627	speaking, you should load it as early as possible. The reason is that	1090	speaking, you should load it as early as possible. The reason is that
628	modules might create watchers when they are loaded, and AnyEvent will	1091	modules might create watchers when they are loaded, and AnyEvent will
629	decide on the event model to use as soon as it creates watchers, and it	1092	decide on the event model to use as soon as it creates watchers, and it
630	might chose the wrong one unless you load the correct one yourself.	1093	might choose the wrong one unless you load the correct one yourself.
631		1094
632	You can chose to use a pure-perl implementation by loading the	1095	You can chose to use a pure-perl implementation by loading the
633	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1096	C<AnyEvent::Loop> module, which gives you similar behaviour
634	everywhere, but letting AnyEvent chose the model is generally better.	1097	everywhere, but letting AnyEvent chose the model is generally better.
635		1098
636	=head2 MAINLOOP EMULATION	1099	=head2 MAINLOOP EMULATION
637		1100
638	Sometimes (often for short test scripts, or even standalone programs who	1101	Sometimes (often for short test scripts, or even standalone programs who
…		…
651		1114
652		1115
653	=head1 OTHER MODULES	1116	=head1 OTHER MODULES
654		1117
655	The following is a non-exhaustive list of additional modules that use	1118	The following is a non-exhaustive list of additional modules that use
656	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1119	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
657	in the same program. Some of the modules come with AnyEvent, some are	1120	modules and other event loops in the same program. Some of the modules
658	available via CPAN.	1121	come as part of AnyEvent, the others are available via CPAN.
659		1122
660	=over 4	1123	=over 4
661		1124
662	=item L<AnyEvent::Util>	1125	=item L<AnyEvent::Util>
663		1126
664	Contains various utility functions that replace often-used but blocking	1127	Contains various utility functions that replace often-used blocking
665	functions such as C<inet_aton> by event-/callback-based versions.	1128	functions such as C<inet_aton> with event/callback-based versions.
666
667	=item L<AnyEvent::Handle>
668
669	Provide read and write buffers and manages watchers for reads and writes.
670		1129
671	=item L<AnyEvent::Socket>	1130	=item L<AnyEvent::Socket>
672		1131
673	Provides various utility functions for (internet protocol) sockets,	1132	Provides various utility functions for (internet protocol) sockets,
674	addresses and name resolution. Also functions to create non-blocking tcp	1133	addresses and name resolution. Also functions to create non-blocking tcp
675	connections or tcp servers, with IPv6 and SRV record support and more.	1134	connections or tcp servers, with IPv6 and SRV record support and more.
676		1135
		1136	=item L<AnyEvent::Handle>
		1137
		1138	Provide read and write buffers, manages watchers for reads and writes,
		1139	supports raw and formatted I/O, I/O queued and fully transparent and
		1140	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1141
677	=item L<AnyEvent::DNS>	1142	=item L<AnyEvent::DNS>
678		1143
679	Provides rich asynchronous DNS resolver capabilities.	1144	Provides rich asynchronous DNS resolver capabilities.
680		1145
		1146	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1147
		1148	Implement event-based interfaces to the protocols of the same name (for
		1149	the curious, IGS is the International Go Server and FCP is the Freenet
		1150	Client Protocol).
		1151
		1152	=item L<AnyEvent::Handle::UDP>
		1153
		1154	Here be danger!
		1155
		1156	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1157	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1158	its use of a stream-based API with a protocol that isn't streamable, that
		1159	the only way to improve it is to delete it.
		1160
		1161	It features data corruption (but typically only under load) and general
		1162	confusion. On top, the author is not only clueless about UDP but also
		1163	fact-resistant - some gems of his understanding: "connect doesn't work
		1164	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1165	packets", "I don't need to implement proper error checking as UDP doesn't
		1166	support error checking" and so on - he doesn't even understand what's
		1167	wrong with his module when it is explained to him.
		1168
		1169	=item L<AnyEvent::DBI>
		1170
		1171	Executes L<DBI> requests asynchronously in a proxy process for you,
		1172	notifying you in an event-based way when the operation is finished.
		1173
		1174	=item L<AnyEvent::AIO>
		1175
		1176	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1177	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1178	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1179	file I/O, and much more.
		1180
681	=item L<AnyEvent::HTTPD>	1181	=item L<AnyEvent::HTTPD>
682		1182
683	Provides a simple web application server framework.	1183	A simple embedded webserver.
684		1184
685	=item L<AnyEvent::FastPing>	1185	=item L<AnyEvent::FastPing>
686		1186
687	The fastest ping in the west.	1187	The fastest ping in the west.
688		1188
689	=item L<Net::IRC3>
690
691	AnyEvent based IRC client module family.
692
693	=item L<Net::XMPP2>
694
695	AnyEvent based XMPP (Jabber protocol) module family.
696
697	=item L<Net::FCP>
698
699	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
700	of AnyEvent.
701
702	=item L<Event::ExecFlow>
703
704	High level API for event-based execution flow control.
705
706	=item L<Coro>	1189	=item L<Coro>
707		1190
708	Has special support for AnyEvent via L<Coro::AnyEvent>.	1191	Has special support for AnyEvent via L<Coro::AnyEvent>.
709		1192
710	=item L<AnyEvent::AIO>, L<IO::AIO>
711
712	Truly asynchronous I/O, should be in the toolbox of every event
713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714	together.
715
716	=item L<AnyEvent::BDB>, L<BDB>
717
718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719	IO::AIO and AnyEvent together.
720
721	=item L<IO::Lambda>
722
723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724
725	=back	1193	=back
726		1194
727	=cut	1195	=cut
728		1196
729	package AnyEvent;	1197	package AnyEvent;
730		1198
731	no warnings;	1199	# basically a tuned-down version of common::sense
732	use strict;	1200	sub common_sense {
		1201	# from common:.sense 3.4
		1202	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1203	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1204	$^H |= 0x00000600;
		1205	}
733		1206
		1207	BEGIN { AnyEvent::common_sense }
		1208
734	use Carp;	1209	use Carp ();
735		1210
736	our $VERSION = '4.04';	1211	our $VERSION = '6.0';
737	our $MODEL;	1212	our $MODEL;
738		1213
739	our $AUTOLOAD;
740	our @ISA;	1214	our @ISA;
741		1215
742	our @REGISTRY;	1216	our @REGISTRY;
743		1217
744	our $WIN32;	1218	our $VERBOSE;
745		1219
746	BEGIN {	1220	BEGIN {
747	my $win32 = ! ! ($^O =~ /mswin32/i);	1221	require "AnyEvent/constants.pl";
748	eval "sub WIN32(){ $win32 }";
749	}
750		1222
		1223	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1224
		1225	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1226	if ${^TAINT};
		1227
751	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1228	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1229
		1230	}
		1231
		1232	our $MAX_SIGNAL_LATENCY = 10;
752		1233
753	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1234	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
754		1235
755	{	1236	{
756	my $idx;	1237	my $idx;
757	$PROTOCOL{$_} = ++$idx	1238	$PROTOCOL{$_} = ++$idx
758	for reverse split /\s*,\s*/,	1239	for reverse split /\s*,\s*/,
759	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1240	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
760	}	1241	}
761		1242
762	sub import {	1243	our @post_detect;
763	shift;
764	return unless @_;
765		1244
766	my $pkg = caller;	1245	sub post_detect(&) {
		1246	my ($cb) = @_;
767		1247
768	no strict 'refs';	1248	push @post_detect, $cb;
769		1249
770	for (@_) {	1250	defined wantarray
771	*{"$pkg\::WIN32"} = *WIN32 if $_ eq "WIN32";	1251	? bless \$cb, "AnyEvent::Util::postdetect"
772	}	1252	: ()
773	}	1253	}
774		1254
		1255	sub AnyEvent::Util::postdetect::DESTROY {
		1256	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1257	}
		1258
		1259	our $POSTPONE_W;
		1260	our @POSTPONE;
		1261
		1262	sub _postpone_exec {
		1263	undef $POSTPONE_W;
		1264
		1265	&{ shift @POSTPONE }
		1266	while @POSTPONE;
		1267	}
		1268
		1269	sub postpone(&) {
		1270	push @POSTPONE, shift;
		1271
		1272	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1273
		1274	()
		1275	}
		1276
775	my @models = (	1277	our @models = (
776	[EV:: => AnyEvent::Impl::EV::],	1278	[EV:: => AnyEvent::Impl::EV:: , 1],
777	[Event:: => AnyEvent::Impl::Event::],	1279	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
778	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
779	# everything below here will not be autoprobed	1280	# everything below here will not (normally) be autoprobed
780	# as the pureperl backend should work everywhere	1281	# as the pure perl backend should work everywhere
781	# and is usually faster	1282	# and is usually faster
		1283	[Event:: => AnyEvent::Impl::Event::, 1],
		1284	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1285	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1286	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
782	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1287	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
783	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
784	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
785	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1288	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
786	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1289	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
787	[Wx:: => AnyEvent::Impl::POE::],	1290	[Wx:: => AnyEvent::Impl::POE::],
788	[Prima:: => AnyEvent::Impl::POE::],	1291	[Prima:: => AnyEvent::Impl::POE::],
		1292	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1293	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1294	[FLTK:: => AnyEvent::Impl::FLTK2::],
789	);	1295	);
790		1296
791	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1297	# all autoloaded methods reserve the complete glob, not just the method slot.
		1298	# due to bugs in perls method cache implementation.
		1299	our @methods = qw(io timer time now now_update signal child idle condvar);
792		1300
793	our @post_detect;
794
795	sub post_detect(&) {	1301	sub detect() {
796	my ($cb) = @_;	1302	local $!; # for good measure
		1303	local $SIG{__DIE__}; # we use eval
797		1304
798	if ($MODEL) {	1305	# free some memory
799	$cb->();	1306	*detect = sub () { $MODEL };
		1307	# undef &func doesn't correctly update the method cache. grmbl.
		1308	# so we delete the whole glob. grmbl.
		1309	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1310	# a glob with an active sub. hrm. i hope it works, but perl is
		1311	# usually buggy in this department. sigh.
		1312	delete @{"AnyEvent::"}{@methods};
		1313	undef @methods;
800		1314
801	1	1315	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1316	my $model = $1;
		1317	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1318	if (eval "require $model") {
		1319	$MODEL = $model;
		1320	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
802	} else {	1321	} else {
803	push @post_detect, $cb;	1322	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
804		1323	}
805	defined wantarray
806	? bless \$cb, "AnyEvent::Util::PostDetect"
807	: ()
808	}	1324	}
809	}
810		1325
811	sub AnyEvent::Util::PostDetect::DESTROY {	1326	# check for already loaded models
812	@post_detect = grep $_ != ${$_[0]}, @post_detect;
813	}
814
815	sub detect() {
816	unless ($MODEL) {	1327	unless ($MODEL) {
817	no strict 'refs';	1328	for (@REGISTRY, @models) {
818	local $SIG{__DIE__};	1329	my ($package, $model) = @$_;
819		1330	if (${"$package\::VERSION"} > 0) {
820	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
821	my $model = "AnyEvent::Impl::$1";
822	if (eval "require $model") {	1331	if (eval "require $model") {
823	$MODEL = $model;	1332	$MODEL = $model;
824	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1333	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
825	} else {	1334	last;
826	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1335	}
827	}	1336	}
828	}	1337	}
829		1338
830	# check for already loaded models
831	unless ($MODEL) {	1339	unless ($MODEL) {
		1340	# try to autoload a model
832	for (@REGISTRY, @models) {	1341	for (@REGISTRY, @models) {
833	my ($package, $model) = @$_;	1342	my ($package, $model, $autoload) = @$_;
		1343	if (
		1344	$autoload
		1345	and eval "require $package"
834	if (${"$package\::VERSION"} > 0) {	1346	and ${"$package\::VERSION"} > 0
835	if (eval "require $model") {	1347	and eval "require $model"
		1348	) {
836	$MODEL = $model;	1349	$MODEL = $model;
837	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1350	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
838	last;	1351	last;
839	}
840	}	1352	}
841	}	1353	}
842		1354
843	unless ($MODEL) {	1355	$MODEL
844	# try to load a model	1356	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
		1357	}
		1358	}
845		1359
846	for (@REGISTRY, @models) {	1360	# free memory only needed for probing
847	my ($package, $model) = @$_;	1361	undef @models;
848	if (eval "require $package"	1362	undef @REGISTRY;
849	and ${"$package\::VERSION"} > 0	1363
850	and eval "require $model") {	1364	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
851	$MODEL = $model;	1365	unshift @ISA, $MODEL;
852	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1366
		1367	# now nuke some methods that are overridden by the backend.
		1368	# SUPER usage is not allowed in these.
		1369	for (qw(time signal child idle)) {
		1370	undef &{"AnyEvent::Base::$_"}
		1371	if defined &{"$MODEL\::$_"};
		1372	}
		1373
		1374	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1375	require AnyEvent::Strict;
		1376	}
		1377
		1378	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1379	require AnyEvent::Debug;
		1380	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1381	}
		1382
		1383	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1384	require AnyEvent::Socket;
		1385	require AnyEvent::Debug;
		1386
		1387	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1388	$shell =~ s/\$\$/$$/g;
		1389
		1390	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1391	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1392	}
		1393
		1394	(shift @post_detect)->() while @post_detect;
		1395	undef @post_detect;
		1396
		1397	*post_detect = sub(&) {
		1398	shift->();
		1399
		1400	undef
		1401	};
		1402
		1403	$MODEL
		1404	}
		1405
		1406	for my $name (@methods) {
		1407	*$name = sub {
		1408	detect;
		1409	# we use goto because
		1410	# a) it makes the thunk more transparent
		1411	# b) it allows us to delete the thunk later
		1412	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1413	};
		1414	}
		1415
		1416	# utility function to dup a filehandle. this is used by many backends
		1417	# to support binding more than one watcher per filehandle (they usually
		1418	# allow only one watcher per fd, so we dup it to get a different one).
		1419	sub _dupfh($$;$$) {
		1420	my ($poll, $fh, $r, $w) = @_;
		1421
		1422	# cygwin requires the fh mode to be matching, unix doesn't
		1423	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1424
		1425	open my $fh2, $mode, $fh
		1426	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1427
		1428	# we assume CLOEXEC is already set by perl in all important cases
		1429
		1430	($fh2, $rw)
		1431	}
		1432
		1433	=head1 SIMPLIFIED AE API
		1434
		1435	Starting with version 5.0, AnyEvent officially supports a second, much
		1436	simpler, API that is designed to reduce the calling, typing and memory
		1437	overhead by using function call syntax and a fixed number of parameters.
		1438
		1439	See the L<AE> manpage for details.
		1440
		1441	=cut
		1442
		1443	package AE;
		1444
		1445	our $VERSION = $AnyEvent::VERSION;
		1446
		1447	sub _reset() {
		1448	eval q{
		1449	# fall back to the main API by default - backends and AnyEvent::Base
		1450	# implementations can overwrite these.
		1451
		1452	sub io($$$) {
		1453	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1454	}
		1455
		1456	sub timer($$$) {
		1457	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1458	}
		1459
		1460	sub signal($$) {
		1461	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1462	}
		1463
		1464	sub child($$) {
		1465	AnyEvent->child (pid => $_[0], cb => $_[1])
		1466	}
		1467
		1468	sub idle($) {
		1469	AnyEvent->idle (cb => $_[0]);
		1470	}
		1471
		1472	sub cv(;&) {
		1473	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1474	}
		1475
		1476	sub now() {
		1477	AnyEvent->now
		1478	}
		1479
		1480	sub now_update() {
		1481	AnyEvent->now_update
		1482	}
		1483
		1484	sub time() {
		1485	AnyEvent->time
		1486	}
		1487
		1488	*postpone = \&AnyEvent::postpone;
		1489	};
		1490	die if $@;
		1491	}
		1492
		1493	BEGIN { _reset }
		1494
		1495	package AnyEvent::Base;
		1496
		1497	# default implementations for many methods
		1498
		1499	sub time {
		1500	eval q{ # poor man's autoloading {}
		1501	# probe for availability of Time::HiRes
		1502	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1503	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1504	*AE::time = \&Time::HiRes::time;
		1505	# if (eval "use POSIX (); (POSIX::times())...
		1506	} else {
		1507	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1508	*AE::time = sub (){ time }; # epic fail
		1509	}
		1510
		1511	*time = sub { AE::time }; # different prototypes
		1512	};
		1513	die if $@;
		1514
		1515	&time
		1516	}
		1517
		1518	*now = \&time;
		1519
		1520	sub now_update { }
		1521
		1522	sub _poll {
		1523	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1524	}
		1525
		1526	# default implementation for ->condvar
		1527	# in fact, the default should not be overwritten
		1528
		1529	sub condvar {
		1530	eval q{ # poor man's autoloading {}
		1531	*condvar = sub {
		1532	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1533	};
		1534
		1535	*AE::cv = sub (;&) {
		1536	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1537	};
		1538	};
		1539	die if $@;
		1540
		1541	&condvar
		1542	}
		1543
		1544	# default implementation for ->signal
		1545
		1546	our $HAVE_ASYNC_INTERRUPT;
		1547
		1548	sub _have_async_interrupt() {
		1549	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1550	&& eval "use Async::Interrupt 1.02 (); 1")
		1551	unless defined $HAVE_ASYNC_INTERRUPT;
		1552
		1553	$HAVE_ASYNC_INTERRUPT
		1554	}
		1555
		1556	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1557	our (%SIG_ASY, %SIG_ASY_W);
		1558	our ($SIG_COUNT, $SIG_TW);
		1559
		1560	# install a dummy wakeup watcher to reduce signal catching latency
		1561	# used by Impls
		1562	sub _sig_add() {
		1563	unless ($SIG_COUNT++) {
		1564	# try to align timer on a full-second boundary, if possible
		1565	my $NOW = AE::now;
		1566
		1567	$SIG_TW = AE::timer
		1568	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1569	$MAX_SIGNAL_LATENCY,
		1570	sub { } # just for the PERL_ASYNC_CHECK
		1571	;
		1572	}
		1573	}
		1574
		1575	sub _sig_del {
		1576	undef $SIG_TW
		1577	unless --$SIG_COUNT;
		1578	}
		1579
		1580	our $_sig_name_init; $_sig_name_init = sub {
		1581	eval q{ # poor man's autoloading {}
		1582	undef $_sig_name_init;
		1583
		1584	if (_have_async_interrupt) {
		1585	*sig2num = \&Async::Interrupt::sig2num;
		1586	*sig2name = \&Async::Interrupt::sig2name;
		1587	} else {
		1588	require Config;
		1589
		1590	my %signame2num;
		1591	@signame2num{ split ' ', $Config::Config{sig_name} }
		1592	= split ' ', $Config::Config{sig_num};
		1593
		1594	my @signum2name;
		1595	@signum2name[values %signame2num] = keys %signame2num;
		1596
		1597	*sig2num = sub($) {
		1598	$_[0] > 0 ? shift : $signame2num{+shift}
		1599	};
		1600	*sig2name = sub ($) {
		1601	$_[0] > 0 ? $signum2name[+shift] : shift
		1602	};
		1603	}
		1604	};
		1605	die if $@;
		1606	};
		1607
		1608	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1609	sub sig2name($) { &$_sig_name_init; &sig2name }
		1610
		1611	sub signal {
		1612	eval q{ # poor man's autoloading {}
		1613	# probe for availability of Async::Interrupt
		1614	if (_have_async_interrupt) {
		1615	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1616
		1617	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1618	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1619
		1620	} else {
		1621	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1622
		1623	if (AnyEvent::WIN32) {
		1624	require AnyEvent::Util;
		1625
		1626	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1627	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1628	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1629	} else {
		1630	pipe $SIGPIPE_R, $SIGPIPE_W;
		1631	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1632	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1633
		1634	# not strictly required, as $^F is normally 2, but let's make sure...
		1635	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1636	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1637	}
		1638
		1639	$SIGPIPE_R
		1640	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1641
		1642	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1643	}
		1644
		1645	*signal = $HAVE_ASYNC_INTERRUPT
		1646	? sub {
		1647	my (undef, %arg) = @_;
		1648
		1649	# async::interrupt
		1650	my $signal = sig2num $arg{signal};
		1651	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1652
		1653	$SIG_ASY{$signal} ||= new Async::Interrupt
		1654	cb => sub { undef $SIG_EV{$signal} },
		1655	signal => $signal,
		1656	pipe => [$SIGPIPE_R->filenos],
		1657	pipe_autodrain => 0,
		1658	;
		1659
		1660	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1661	}
		1662	: sub {
		1663	my (undef, %arg) = @_;
		1664
		1665	# pure perl
		1666	my $signal = sig2name $arg{signal};
		1667	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1668
		1669	$SIG{$signal} ||= sub {
853	last;	1670	local $!;
		1671	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1672	undef $SIG_EV{$signal};
854	}	1673	};
		1674
		1675	# can't do signal processing without introducing races in pure perl,
		1676	# so limit the signal latency.
		1677	_sig_add;
		1678
		1679	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1680	}
		1681	;
		1682
		1683	*AnyEvent::Base::signal::DESTROY = sub {
		1684	my ($signal, $cb) = @{$_[0]};
		1685
		1686	_sig_del;
		1687
		1688	delete $SIG_CB{$signal}{$cb};
		1689
		1690	$HAVE_ASYNC_INTERRUPT
		1691	? delete $SIG_ASY{$signal}
		1692	: # delete doesn't work with older perls - they then
		1693	# print weird messages, or just unconditionally exit
		1694	# instead of getting the default action.
		1695	undef $SIG{$signal}
		1696	unless keys %{ $SIG_CB{$signal} };
		1697	};
		1698
		1699	*_signal_exec = sub {
		1700	$HAVE_ASYNC_INTERRUPT
		1701	? $SIGPIPE_R->drain
		1702	: sysread $SIGPIPE_R, (my $dummy), 9;
		1703
		1704	while (%SIG_EV) {
		1705	for (keys %SIG_EV) {
		1706	delete $SIG_EV{$_};
		1707	&$_ for values %{ $SIG_CB{$_} || {} };
855	}	1708	}
856
857	$MODEL
858	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
859	}	1709	}
860	}	1710	};
861
862	unshift @ISA, $MODEL;
863	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
864
865	(shift @post_detect)->() while @post_detect;
866	}
867
868	$MODEL
869	}
870
871	sub AUTOLOAD {
872	(my $func = $AUTOLOAD) =~ s/.*://;
873
874	$method{$func}
875	or croak "$func: not a valid method for AnyEvent objects";
876
877	detect unless $MODEL;
878
879	my $class = shift;
880	$class->$func (@_);
881	}
882
883	package AnyEvent::Base;
884
885	# default implementation for ->condvar
886
887	sub condvar {
888	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
889	}
890
891	# default implementation for ->signal
892
893	our %SIG_CB;
894
895	sub signal {
896	my (undef, %arg) = @_;
897
898	my $signal = uc $arg{signal}
899	or Carp::croak "required option 'signal' is missing";
900
901	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
902	$SIG{$signal} ||= sub {
903	$_->() for values %{ $SIG_CB{$signal} || {} };
904	};	1711	};
		1712	die if $@;
905		1713
906	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1714	&signal
907	}
908
909	sub AnyEvent::Base::Signal::DESTROY {
910	my ($signal, $cb) = @{$_[0]};
911
912	delete $SIG_CB{$signal}{$cb};
913
914	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
915	}	1715	}
916		1716
917	# default implementation for ->child	1717	# default implementation for ->child
918		1718
919	our %PID_CB;	1719	our %PID_CB;
920	our $CHLD_W;	1720	our $CHLD_W;
921	our $CHLD_DELAY_W;	1721	our $CHLD_DELAY_W;
922	our $PID_IDLE;
923	our $WNOHANG;
924		1722
925	sub _child_wait {	1723	# used by many Impl's
926	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1724	sub _emit_childstatus($$) {
		1725	my (undef, $rpid, $rstatus) = @_;
		1726
		1727	$_->($rpid, $rstatus)
927	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1728	for values %{ $PID_CB{$rpid} || {} },
928	(values %{ $PID_CB{0} || {} });	1729	values %{ $PID_CB{0} || {} };
929	}
930
931	undef $PID_IDLE;
932	}
933
934	sub _sigchld {
935	# make sure we deliver these changes "synchronous" with the event loop.
936	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
937	undef $CHLD_DELAY_W;
938	&_child_wait;
939	});
940	}	1730	}
941		1731
942	sub child {	1732	sub child {
		1733	eval q{ # poor man's autoloading {}
		1734	*_sigchld = sub {
		1735	my $pid;
		1736
		1737	AnyEvent->_emit_childstatus ($pid, $?)
		1738	while ($pid = waitpid -1, WNOHANG) > 0;
		1739	};
		1740
		1741	*child = sub {
943	my (undef, %arg) = @_;	1742	my (undef, %arg) = @_;
944		1743
945	defined (my $pid = $arg{pid} + 0)	1744	my $pid = $arg{pid};
946	or Carp::croak "required option 'pid' is missing";	1745	my $cb = $arg{cb};
947		1746
948	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1747	$PID_CB{$pid}{$cb+0} = $cb;
949		1748
950	unless ($WNOHANG) {
951	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
952	}
953
954	unless ($CHLD_W) {	1749	unless ($CHLD_W) {
955	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1750	$CHLD_W = AE::signal CHLD => \&_sigchld;
956	# child could be a zombie already, so make at least one round	1751	# child could be a zombie already, so make at least one round
957	&_sigchld;	1752	&_sigchld;
958	}	1753	}
959		1754
960	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1755	bless [$pid, $cb+0], "AnyEvent::Base::child"
961	}	1756	};
962		1757
963	sub AnyEvent::Base::Child::DESTROY {	1758	*AnyEvent::Base::child::DESTROY = sub {
964	my ($pid, $cb) = @{$_[0]};	1759	my ($pid, $icb) = @{$_[0]};
965		1760
966	delete $PID_CB{$pid}{$cb};	1761	delete $PID_CB{$pid}{$icb};
967	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1762	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
968		1763
969	undef $CHLD_W unless keys %PID_CB;	1764	undef $CHLD_W unless keys %PID_CB;
		1765	};
		1766	};
		1767	die if $@;
		1768
		1769	&child
		1770	}
		1771
		1772	# idle emulation is done by simply using a timer, regardless
		1773	# of whether the process is idle or not, and not letting
		1774	# the callback use more than 50% of the time.
		1775	sub idle {
		1776	eval q{ # poor man's autoloading {}
		1777	*idle = sub {
		1778	my (undef, %arg) = @_;
		1779
		1780	my ($cb, $w, $rcb) = $arg{cb};
		1781
		1782	$rcb = sub {
		1783	if ($cb) {
		1784	$w = AE::time;
		1785	&$cb;
		1786	$w = AE::time - $w;
		1787
		1788	# never use more then 50% of the time for the idle watcher,
		1789	# within some limits
		1790	$w = 0.0001 if $w < 0.0001;
		1791	$w = 5 if $w > 5;
		1792
		1793	$w = AE::timer $w, 0, $rcb;
		1794	} else {
		1795	# clean up...
		1796	undef $w;
		1797	undef $rcb;
		1798	}
		1799	};
		1800
		1801	$w = AE::timer 0.05, 0, $rcb;
		1802
		1803	bless \\$cb, "AnyEvent::Base::idle"
		1804	};
		1805
		1806	*AnyEvent::Base::idle::DESTROY = sub {
		1807	undef $${$_[0]};
		1808	};
		1809	};
		1810	die if $@;
		1811
		1812	&idle
970	}	1813	}
971		1814
972	package AnyEvent::CondVar;	1815	package AnyEvent::CondVar;
973		1816
974	our @ISA = AnyEvent::CondVar::Base::;	1817	our @ISA = AnyEvent::CondVar::Base::;
975		1818
		1819	# only to be used for subclassing
		1820	sub new {
		1821	my $class = shift;
		1822	bless AnyEvent->condvar (@_), $class
		1823	}
		1824
976	package AnyEvent::CondVar::Base;	1825	package AnyEvent::CondVar::Base;
977		1826
978	use overload	1827	#use overload
979	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1828	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
980	fallback => 1;	1829	# fallback => 1;
		1830
		1831	# save 300+ kilobytes by dirtily hardcoding overloading
		1832	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1833	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1834	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1835	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1836
		1837	our $WAITING;
981		1838
982	sub _send {	1839	sub _send {
983	# nop	1840	# nop
		1841	}
		1842
		1843	sub _wait {
		1844	AnyEvent->_poll until $_[0]{_ae_sent};
984	}	1845	}
985		1846
986	sub send {	1847	sub send {
987	my $cv = shift;	1848	my $cv = shift;
988	$cv->{_ae_sent} = [@_];	1849	$cv->{_ae_sent} = [@_];
…		…
997		1858
998	sub ready {	1859	sub ready {
999	$_[0]{_ae_sent}	1860	$_[0]{_ae_sent}
1000	}	1861	}
1001		1862
1002	sub _wait {
1003	AnyEvent->one_event while !$_[0]{_ae_sent};
1004	}
1005
1006	sub recv {	1863	sub recv {
		1864	unless ($_[0]{_ae_sent}) {
		1865	$WAITING
		1866	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1867
		1868	local $WAITING = 1;
1007	$_[0]->_wait;	1869	$_[0]->_wait;
		1870	}
1008		1871
1009	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1872	$_[0]{_ae_croak}
1010	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1873	and Carp::croak $_[0]{_ae_croak};
		1874
		1875	wantarray
		1876	? @{ $_[0]{_ae_sent} }
		1877	: $_[0]{_ae_sent}[0]
1011	}	1878	}
1012		1879
1013	sub cb {	1880	sub cb {
1014	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1881	my $cv = shift;
		1882
		1883	@_
		1884	and $cv->{_ae_cb} = shift
		1885	and $cv->{_ae_sent}
		1886	and (delete $cv->{_ae_cb})->($cv);
		1887
1015	$_[0]{_ae_cb}	1888	$cv->{_ae_cb}
1016	}	1889	}
1017		1890
1018	sub begin {	1891	sub begin {
1019	++$_[0]{_ae_counter};	1892	++$_[0]{_ae_counter};
1020	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1893	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1025	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1898	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1026	}	1899	}
1027		1900
1028	# undocumented/compatibility with pre-3.4	1901	# undocumented/compatibility with pre-3.4
1029	*broadcast = \&send;	1902	*broadcast = \&send;
1030	*wait = \&_wait;	1903	*wait = \&recv;
		1904
		1905	=head1 ERROR AND EXCEPTION HANDLING
		1906
		1907	In general, AnyEvent does not do any error handling - it relies on the
		1908	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1909	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1910	checking of all AnyEvent methods, however, which is highly useful during
		1911	development.
		1912
		1913	As for exception handling (i.e. runtime errors and exceptions thrown while
		1914	executing a callback), this is not only highly event-loop specific, but
		1915	also not in any way wrapped by this module, as this is the job of the main
		1916	program.
		1917
		1918	The pure perl event loop simply re-throws the exception (usually
		1919	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1920	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1921	so on.
		1922
		1923	=head1 ENVIRONMENT VARIABLES
		1924
		1925	The following environment variables are used by this module or its
		1926	submodules.
		1927
		1928	Note that AnyEvent will remove I<all> environment variables starting with
		1929	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1930	enabled.
		1931
		1932	=over 4
		1933
		1934	=item C<PERL_ANYEVENT_VERBOSE>
		1935
		1936	By default, AnyEvent will be completely silent except in fatal
		1937	conditions. You can set this environment variable to make AnyEvent more
		1938	talkative.
		1939
		1940	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1941	conditions, such as not being able to load the event model specified by
		1942	C<PERL_ANYEVENT_MODEL>.
		1943
		1944	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1945	model it chooses.
		1946
		1947	When set to C<8> or higher, then AnyEvent will report extra information on
		1948	which optional modules it loads and how it implements certain features.
		1949
		1950	=item C<PERL_ANYEVENT_STRICT>
		1951
		1952	AnyEvent does not do much argument checking by default, as thorough
		1953	argument checking is very costly. Setting this variable to a true value
		1954	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1955	check the arguments passed to most method calls. If it finds any problems,
		1956	it will croak.
		1957
		1958	In other words, enables "strict" mode.
		1959
		1960	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		1961	>>, it is definitely recommended to keep it off in production. Keeping
		1962	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1963	can be very useful, however.
		1964
		1965	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1966
		1967	If this env variable is set, then its contents will be interpreted by
		1968	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		1969	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		1970	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		1971
		1972	This takes place when the first watcher is created.
		1973
		1974	For example, to bind a debug shell on a unix domain socket in
		1975	F<< /tmp/debug<pid>.sock >>, you could use this:
		1976
		1977	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug\$\$.sock perlprog
		1978
		1979	Note that creating sockets in F</tmp> is very unsafe on multiuser
		1980	systems.
		1981
		1982	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		1983
		1984	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		1985	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		1986
		1987	=item C<PERL_ANYEVENT_MODEL>
		1988
		1989	This can be used to specify the event model to be used by AnyEvent, before
		1990	auto detection and -probing kicks in.
		1991
		1992	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		1993	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		1994	resulting module name is loaded and - if the load was successful - used as
		1995	event model backend. If it fails to load then AnyEvent will proceed with
		1996	auto detection and -probing.
		1997
		1998	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		1999	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2000	the end of a string designates a module name and quotes it appropriately).
		2001
		2002	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		2003	could start your program like this:
		2004
		2005	PERL_ANYEVENT_MODEL=Perl perl ...
		2006
		2007	=item C<PERL_ANYEVENT_PROTOCOLS>
		2008
		2009	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		2010	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		2011	of auto probing).
		2012
		2013	Must be set to a comma-separated list of protocols or address families,
		2014	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2015	used, and preference will be given to protocols mentioned earlier in the
		2016	list.
		2017
		2018	This variable can effectively be used for denial-of-service attacks
		2019	against local programs (e.g. when setuid), although the impact is likely
		2020	small, as the program has to handle conenction and other failures anyways.
		2021
		2022	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2023	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2024	- only support IPv4, never try to resolve or contact IPv6
		2025	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2026	IPv6, but prefer IPv6 over IPv4.
		2027
		2028	=item C<PERL_ANYEVENT_EDNS0>
		2029
		2030	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		2031	for DNS. This extension is generally useful to reduce DNS traffic, but
		2032	some (broken) firewalls drop such DNS packets, which is why it is off by
		2033	default.
		2034
		2035	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2036	EDNS0 in its DNS requests.
		2037
		2038	=item C<PERL_ANYEVENT_MAX_FORKS>
		2039
		2040	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2041	will create in parallel.
		2042
		2043	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2044
		2045	The default value for the C<max_outstanding> parameter for the default DNS
		2046	resolver - this is the maximum number of parallel DNS requests that are
		2047	sent to the DNS server.
		2048
		2049	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2050
		2051	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2052	configuration) in the default resolver. When set to the empty string, no
		2053	default config will be used.
		2054
		2055	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2056
		2057	When neither C<ca_file> nor C<ca_path> was specified during
		2058	L<AnyEvent::TLS> context creation, and either of these environment
		2059	variables exist, they will be used to specify CA certificate locations
		2060	instead of a system-dependent default.
		2061
		2062	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2063
		2064	When these are set to C<1>, then the respective modules are not
		2065	loaded. Mostly good for testing AnyEvent itself.
		2066
		2067	=back
1031		2068
1032	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2069	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1033		2070
1034	This is an advanced topic that you do not normally need to use AnyEvent in	2071	This is an advanced topic that you do not normally need to use AnyEvent in
1035	a module. This section is only of use to event loop authors who want to	2072	a module. This section is only of use to event loop authors who want to
…		…
1069		2106
1070	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2107	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1071	condition variables: code blocking while waiting for a condition will	2108	condition variables: code blocking while waiting for a condition will
1072	C<die>. This still works with most modules/usages, and blocking calls must	2109	C<die>. This still works with most modules/usages, and blocking calls must
1073	not be done in an interactive application, so it makes sense.	2110	not be done in an interactive application, so it makes sense.
1074
1075	=head1 ENVIRONMENT VARIABLES
1076
1077	The following environment variables are used by this module:
1078
1079	=over 4
1080
1081	=item C<PERL_ANYEVENT_VERBOSE>
1082
1083	By default, AnyEvent will be completely silent except in fatal
1084	conditions. You can set this environment variable to make AnyEvent more
1085	talkative.
1086
1087	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1088	conditions, such as not being able to load the event model specified by
1089	C<PERL_ANYEVENT_MODEL>.
1090
1091	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1092	model it chooses.
1093
1094	=item C<PERL_ANYEVENT_MODEL>
1095
1096	This can be used to specify the event model to be used by AnyEvent, before
1097	auto detection and -probing kicks in. It must be a string consisting
1098	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1099	and the resulting module name is loaded and if the load was successful,
1100	used as event model. If it fails to load AnyEvent will proceed with
1101	auto detection and -probing.
1102
1103	This functionality might change in future versions.
1104
1105	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1106	could start your program like this:
1107
1108	PERL_ANYEVENT_MODEL=Perl perl ...
1109
1110	=item C<PERL_ANYEVENT_PROTOCOLS>
1111
1112	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1113	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1114	of auto probing).
1115
1116	Must be set to a comma-separated list of protocols or address families,
1117	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1118	used, and preference will be given to protocols mentioned earlier in the
1119	list.
1120
1121	This variable can effectively be used for denial-of-service attacks
1122	against local programs (e.g. when setuid), although the impact is likely
1123	small, as the program has to handle connection errors already-
1124
1125	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1126	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1127	- only support IPv4, never try to resolve or contact IPv6
1128	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1129	IPv6, but prefer IPv6 over IPv4.
1130
1131	=item C<PERL_ANYEVENT_EDNS0>
1132
1133	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1134	for DNS. This extension is generally useful to reduce DNS traffic, but
1135	some (broken) firewalls drop such DNS packets, which is why it is off by
1136	default.
1137
1138	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1139	EDNS0 in its DNS requests.
1140
1141	=back
1142		2111
1143	=head1 EXAMPLE PROGRAM	2112	=head1 EXAMPLE PROGRAM
1144		2113
1145	The following program uses an I/O watcher to read data from STDIN, a timer	2114	The following program uses an I/O watcher to read data from STDIN, a timer
1146	to display a message once per second, and a condition variable to quit the	2115	to display a message once per second, and a condition variable to quit the
…		…
1159	warn "read: $input\n"; # output what has been read	2128	warn "read: $input\n"; # output what has been read
1160	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2129	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1161	},	2130	},
1162	);	2131	);
1163		2132
1164	my $time_watcher; # can only be used once
1165
1166	sub new_timer {
1167	$timer = AnyEvent->timer (after => 1, cb => sub {	2133	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1168	warn "timeout\n"; # print 'timeout' about every second	2134	warn "timeout\n"; # print 'timeout' at most every second
1169	&new_timer; # and restart the time
1170	});	2135	});
1171	}
1172
1173	new_timer; # create first timer
1174		2136
1175	$cv->recv; # wait until user enters /^q/i	2137	$cv->recv; # wait until user enters /^q/i
1176		2138
1177	=head1 REAL-WORLD EXAMPLE	2139	=head1 REAL-WORLD EXAMPLE
1178		2140
…		…
1251		2213
1252	The actual code goes further and collects all errors (C<die>s, exceptions)	2214	The actual code goes further and collects all errors (C<die>s, exceptions)
1253	that occurred during request processing. The C<result> method detects	2215	that occurred during request processing. The C<result> method detects
1254	whether an exception as thrown (it is stored inside the $txn object)	2216	whether an exception as thrown (it is stored inside the $txn object)
1255	and just throws the exception, which means connection errors and other	2217	and just throws the exception, which means connection errors and other
1256	problems get reported tot he code that tries to use the result, not in a	2218	problems get reported to the code that tries to use the result, not in a
1257	random callback.	2219	random callback.
1258		2220
1259	All of this enables the following usage styles:	2221	All of this enables the following usage styles:
1260		2222
1261	1. Blocking:	2223	1. Blocking:
…		…
1309	through AnyEvent. The benchmark creates a lot of timers (with a zero	2271	through AnyEvent. The benchmark creates a lot of timers (with a zero
1310	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2272	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1311	which it is), lets them fire exactly once and destroys them again.	2273	which it is), lets them fire exactly once and destroys them again.
1312		2274
1313	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2275	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1314	distribution.	2276	distribution. It uses the L<AE> interface, which makes a real difference
		2277	for the EV and Perl backends only.
1315		2278
1316	=head3 Explanation of the columns	2279	=head3 Explanation of the columns
1317		2280
1318	I<watcher> is the number of event watchers created/destroyed. Since	2281	I<watcher> is the number of event watchers created/destroyed. Since
1319	different event models feature vastly different performances, each event	2282	different event models feature vastly different performances, each event
…		…
1340	watcher.	2303	watcher.
1341		2304
1342	=head3 Results	2305	=head3 Results
1343		2306
1344	name watchers bytes create invoke destroy comment	2307	name watchers bytes create invoke destroy comment
1345	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2308	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1346	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2309	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1347	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2310	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1348	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2311	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1349	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2312	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1350	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2313	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2314	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2315	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1351	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2316	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1352	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2317	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1353	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2318	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1354	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2319	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1355		2320
1356	=head3 Discussion	2321	=head3 Discussion
1357		2322
1358	The benchmark does I<not> measure scalability of the event loop very	2323	The benchmark does I<not> measure scalability of the event loop very
1359	well. For example, a select-based event loop (such as the pure perl one)	2324	well. For example, a select-based event loop (such as the pure perl one)
…		…
1371	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2336	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1372	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2337	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1373	cycles with POE.	2338	cycles with POE.
1374		2339
1375	C<EV> is the sole leader regarding speed and memory use, which are both	2340	C<EV> is the sole leader regarding speed and memory use, which are both
1376	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2341	maximal/minimal, respectively. When using the L<AE> API there is zero
		2342	overhead (when going through the AnyEvent API create is about 5-6 times
		2343	slower, with other times being equal, so still uses far less memory than
1377	far less memory than any other event loop and is still faster than Event	2344	any other event loop and is still faster than Event natively).
1378	natively.
1379		2345
1380	The pure perl implementation is hit in a few sweet spots (both the	2346	The pure perl implementation is hit in a few sweet spots (both the
1381	constant timeout and the use of a single fd hit optimisations in the perl	2347	constant timeout and the use of a single fd hit optimisations in the perl
1382	interpreter and the backend itself). Nevertheless this shows that it	2348	interpreter and the backend itself). Nevertheless this shows that it
1383	adds very little overhead in itself. Like any select-based backend its	2349	adds very little overhead in itself. Like any select-based backend its
1384	performance becomes really bad with lots of file descriptors (and few of	2350	performance becomes really bad with lots of file descriptors (and few of
1385	them active), of course, but this was not subject of this benchmark.	2351	them active), of course, but this was not subject of this benchmark.
1386		2352
1387	The C<Event> module has a relatively high setup and callback invocation	2353	The C<Event> module has a relatively high setup and callback invocation
1388	cost, but overall scores in on the third place.	2354	cost, but overall scores in on the third place.
		2355
		2356	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2357	when using its pure perl backend.
1389		2358
1390	C<Glib>'s memory usage is quite a bit higher, but it features a	2359	C<Glib>'s memory usage is quite a bit higher, but it features a
1391	faster callback invocation and overall ends up in the same class as	2360	faster callback invocation and overall ends up in the same class as
1392	C<Event>. However, Glib scales extremely badly, doubling the number of	2361	C<Event>. However, Glib scales extremely badly, doubling the number of
1393	watchers increases the processing time by more than a factor of four,	2362	watchers increases the processing time by more than a factor of four,
…		…
1454	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2423	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1455	(1%) are active. This mirrors the activity of large servers with many	2424	(1%) are active. This mirrors the activity of large servers with many
1456	connections, most of which are idle at any one point in time.	2425	connections, most of which are idle at any one point in time.
1457		2426
1458	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2427	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1459	distribution.	2428	distribution. It uses the L<AE> interface, which makes a real difference
		2429	for the EV and Perl backends only.
1460		2430
1461	=head3 Explanation of the columns	2431	=head3 Explanation of the columns
1462		2432
1463	I<sockets> is the number of sockets, and twice the number of "servers" (as	2433	I<sockets> is the number of sockets, and twice the number of "servers" (as
1464	each server has a read and write socket end).	2434	each server has a read and write socket end).
…		…
1471	it to another server. This includes deleting the old timeout and creating	2441	it to another server. This includes deleting the old timeout and creating
1472	a new one that moves the timeout into the future.	2442	a new one that moves the timeout into the future.
1473		2443
1474	=head3 Results	2444	=head3 Results
1475		2445
1476	name sockets create request	2446	name sockets create request
1477	EV 20000 69.01 11.16	2447	EV 20000 62.66 7.99
1478	Perl 20000 73.32 35.87	2448	Perl 20000 68.32 32.64
1479	Event 20000 212.62 257.32	2449	IOAsync 20000 174.06 101.15 epoll
1480	Glib 20000 651.16 1896.30	2450	IOAsync 20000 174.67 610.84 poll
		2451	Event 20000 202.69 242.91
		2452	Glib 20000 557.01 1689.52
1481	POE 20000 349.67 12317.24 uses POE::Loop::Event	2453	POE 20000 341.54 12086.32 uses POE::Loop::Event
1482		2454
1483	=head3 Discussion	2455	=head3 Discussion
1484		2456
1485	This benchmark I<does> measure scalability and overall performance of the	2457	This benchmark I<does> measure scalability and overall performance of the
1486	particular event loop.	2458	particular event loop.
…		…
1488	EV is again fastest. Since it is using epoll on my system, the setup time	2460	EV is again fastest. Since it is using epoll on my system, the setup time
1489	is relatively high, though.	2461	is relatively high, though.
1490		2462
1491	Perl surprisingly comes second. It is much faster than the C-based event	2463	Perl surprisingly comes second. It is much faster than the C-based event
1492	loops Event and Glib.	2464	loops Event and Glib.
		2465
		2466	IO::Async performs very well when using its epoll backend, and still quite
		2467	good compared to Glib when using its pure perl backend.
1493		2468
1494	Event suffers from high setup time as well (look at its code and you will	2469	Event suffers from high setup time as well (look at its code and you will
1495	understand why). Callback invocation also has a high overhead compared to	2470	understand why). Callback invocation also has a high overhead compared to
1496	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2471	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1497	uses select or poll in basically all documented configurations.	2472	uses select or poll in basically all documented configurations.
…		…
1560	=item * C-based event loops perform very well with small number of	2535	=item * C-based event loops perform very well with small number of
1561	watchers, as the management overhead dominates.	2536	watchers, as the management overhead dominates.
1562		2537
1563	=back	2538	=back
1564		2539
		2540	=head2 THE IO::Lambda BENCHMARK
		2541
		2542	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2543	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2544	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2545	shouldn't come as a surprise to anybody). As such, the benchmark is
		2546	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2547	very optimal. But how would AnyEvent compare when used without the extra
		2548	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2549
		2550	The benchmark itself creates an echo-server, and then, for 500 times,
		2551	connects to the echo server, sends a line, waits for the reply, and then
		2552	creates the next connection. This is a rather bad benchmark, as it doesn't
		2553	test the efficiency of the framework or much non-blocking I/O, but it is a
		2554	benchmark nevertheless.
		2555
		2556	name runtime
		2557	Lambda/select 0.330 sec
		2558	+ optimized 0.122 sec
		2559	Lambda/AnyEvent 0.327 sec
		2560	+ optimized 0.138 sec
		2561	Raw sockets/select 0.077 sec
		2562	POE/select, components 0.662 sec
		2563	POE/select, raw sockets 0.226 sec
		2564	POE/select, optimized 0.404 sec
		2565
		2566	AnyEvent/select/nb 0.085 sec
		2567	AnyEvent/EV/nb 0.068 sec
		2568	+state machine 0.134 sec
		2569
		2570	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2571	benchmarks actually make blocking connects and use 100% blocking I/O,
		2572	defeating the purpose of an event-based solution. All of the newly
		2573	written AnyEvent benchmarks use 100% non-blocking connects (using
		2574	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2575	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2576	generally require a lot more bookkeeping and event handling than blocking
		2577	connects (which involve a single syscall only).
		2578
		2579	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2580	offers similar expressive power as POE and IO::Lambda, using conventional
		2581	Perl syntax. This means that both the echo server and the client are 100%
		2582	non-blocking, further placing it at a disadvantage.
		2583
		2584	As you can see, the AnyEvent + EV combination even beats the
		2585	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2586	backend easily beats IO::Lambda and POE.
		2587
		2588	And even the 100% non-blocking version written using the high-level (and
		2589	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2590	higher level ("unoptimised") abstractions by a large margin, even though
		2591	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2592
		2593	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2594	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2595	part of the IO::Lambda distribution and were used without any changes.
		2596
		2597
		2598	=head1 SIGNALS
		2599
		2600	AnyEvent currently installs handlers for these signals:
		2601
		2602	=over 4
		2603
		2604	=item SIGCHLD
		2605
		2606	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2607	emulation for event loops that do not support them natively. Also, some
		2608	event loops install a similar handler.
		2609
		2610	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2611	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2612
		2613	=item SIGPIPE
		2614
		2615	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2616	when AnyEvent gets loaded.
		2617
		2618	The rationale for this is that AnyEvent users usually do not really depend
		2619	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2620	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2621	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2622	some random socket.
		2623
		2624	The rationale for installing a no-op handler as opposed to ignoring it is
		2625	that this way, the handler will be restored to defaults on exec.
		2626
		2627	Feel free to install your own handler, or reset it to defaults.
		2628
		2629	=back
		2630
		2631	=cut
		2632
		2633	undef $SIG{CHLD}
		2634	if $SIG{CHLD} eq 'IGNORE';
		2635
		2636	$SIG{PIPE} = sub { }
		2637	unless defined $SIG{PIPE};
		2638
		2639	=head1 RECOMMENDED/OPTIONAL MODULES
		2640
		2641	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2642	its built-in modules) are required to use it.
		2643
		2644	That does not mean that AnyEvent won't take advantage of some additional
		2645	modules if they are installed.
		2646
		2647	This section explains which additional modules will be used, and how they
		2648	affect AnyEvent's operation.
		2649
		2650	=over 4
		2651
		2652	=item L<Async::Interrupt>
		2653
		2654	This slightly arcane module is used to implement fast signal handling: To
		2655	my knowledge, there is no way to do completely race-free and quick
		2656	signal handling in pure perl. To ensure that signals still get
		2657	delivered, AnyEvent will start an interval timer to wake up perl (and
		2658	catch the signals) with some delay (default is 10 seconds, look for
		2659	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2660
		2661	If this module is available, then it will be used to implement signal
		2662	catching, which means that signals will not be delayed, and the event loop
		2663	will not be interrupted regularly, which is more efficient (and good for
		2664	battery life on laptops).
		2665
		2666	This affects not just the pure-perl event loop, but also other event loops
		2667	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2668
		2669	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2670	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2671	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2672	does nothing for those backends.
		2673
		2674	=item L<EV>
		2675
		2676	This module isn't really "optional", as it is simply one of the backend
		2677	event loops that AnyEvent can use. However, it is simply the best event
		2678	loop available in terms of features, speed and stability: It supports
		2679	the AnyEvent API optimally, implements all the watcher types in XS, does
		2680	automatic timer adjustments even when no monotonic clock is available,
		2681	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2682	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2683	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2684
		2685	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2686	then this module will do nothing for you.
		2687
		2688	=item L<Guard>
		2689
		2690	The guard module, when used, will be used to implement
		2691	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2692	lot less memory), but otherwise doesn't affect guard operation much. It is
		2693	purely used for performance.
		2694
		2695	=item L<JSON> and L<JSON::XS>
		2696
		2697	One of these modules is required when you want to read or write JSON data
		2698	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2699	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2700
		2701	=item L<Net::SSLeay>
		2702
		2703	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2704	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2705	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2706
		2707	=item L<Time::HiRes>
		2708
		2709	This module is part of perl since release 5.008. It will be used when the
		2710	chosen event library does not come with a timing source of its own. The
		2711	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2712	try to use a monotonic clock for timing stability.
		2713
		2714	=back
		2715
1565		2716
1566	=head1 FORK	2717	=head1 FORK
1567		2718
1568	Most event libraries are not fork-safe. The ones who are usually are	2719	Most event libraries are not fork-safe. The ones who are usually are
1569	because they rely on inefficient but fork-safe C<select> or C<poll>	2720	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1570	calls. Only L<EV> is fully fork-aware.	2721	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2722	are usually badly thought-out hacks that are incompatible with fork in
		2723	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2724	continue event-processing in both parent and child (or both, if you know
		2725	what you are doing).
		2726
		2727	This means that, in general, you cannot fork and do event processing in
		2728	the child if the event library was initialised before the fork (which
		2729	usually happens when the first AnyEvent watcher is created, or the library
		2730	is loaded).
1571		2731
1572	If you have to fork, you must either do so I<before> creating your first	2732	If you have to fork, you must either do so I<before> creating your first
1573	watcher OR you must not use AnyEvent at all in the child.	2733	watcher OR you must not use AnyEvent at all in the child OR you must do
		2734	something completely out of the scope of AnyEvent.
		2735
		2736	The problem of doing event processing in the parent I<and> the child
		2737	is much more complicated: even for backends that I<are> fork-aware or
		2738	fork-safe, their behaviour is not usually what you want: fork clones all
		2739	watchers, that means all timers, I/O watchers etc. are active in both
		2740	parent and child, which is almost never what you want. USing C<exec>
		2741	to start worker children from some kind of manage rprocess is usually
		2742	preferred, because it is much easier and cleaner, at the expense of having
		2743	to have another binary.
1574		2744
1575		2745
1576	=head1 SECURITY CONSIDERATIONS	2746	=head1 SECURITY CONSIDERATIONS
1577		2747
1578	AnyEvent can be forced to load any event model via	2748	AnyEvent can be forced to load any event model via
…		…
1583	specified in the variable.	2753	specified in the variable.
1584		2754
1585	You can make AnyEvent completely ignore this variable by deleting it	2755	You can make AnyEvent completely ignore this variable by deleting it
1586	before the first watcher gets created, e.g. with a C<BEGIN> block:	2756	before the first watcher gets created, e.g. with a C<BEGIN> block:
1587		2757
1588	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2758	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1589		2759
1590	use AnyEvent;	2760	use AnyEvent;
1591		2761
1592	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2762	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1593	be used to probe what backend is used and gain other information (which is	2763	be used to probe what backend is used and gain other information (which is
1594	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2764	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2765	$ENV{PERL_ANYEVENT_STRICT}.
		2766
		2767	Note that AnyEvent will remove I<all> environment variables starting with
		2768	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2769	enabled.
		2770
		2771
		2772	=head1 BUGS
		2773
		2774	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2775	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2776	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2777	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2778	pronounced).
1595		2779
1596		2780
1597	=head1 SEE ALSO	2781	=head1 SEE ALSO
1598		2782
		2783	Tutorial/Introduction: L<AnyEvent::Intro>.
		2784
		2785	FAQ: L<AnyEvent::FAQ>.
		2786
1599	Utility functions: L<AnyEvent::Util>.	2787	Utility functions: L<AnyEvent::Util>.
1600		2788
1601	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2789	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
1602	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2790	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1603		2791
1604	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2792	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1605	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2793	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1606	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2794	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1607	L<AnyEvent::Impl::POE>.	2795	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1608		2796
1609	Non-blocking file handles, sockets, TCP clients and	2797	Non-blocking file handles, sockets, TCP clients and
1610	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2798	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1611		2799
1612	Asynchronous DNS: L<AnyEvent::DNS>.	2800	Asynchronous DNS: L<AnyEvent::DNS>.
1613		2801
1614	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2802	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1615		2803
1616	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2804	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2805	L<AnyEvent::HTTP>.
1617		2806
1618		2807
1619	=head1 AUTHOR	2808	=head1 AUTHOR
1620		2809
1621	Marc Lehmann <schmorp@schmorp.de>	2810	Marc Lehmann <schmorp@schmorp.de>
1622	http://home.schmorp.de/	2811	http://home.schmorp.de/
1623		2812
1624	=cut	2813	=cut
1625		2814
1626	1	2815	1
1627		2816

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