ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC vs.
Revision 1.358 by root, Sat Aug 13 02:35:32 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).	575	were a callback, read about the caveats in the description for the C<<
		576	->send >> method).
318		577
319	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
320	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:
321	in time where multiple outstanding events have been processed. And yet	580
322	another way to call them is transactions - each condition variable can be	581	=over 4
323	used to represent a transaction, which finishes at some point and delivers	582
324	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
325		601
326	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
327	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,
328	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
329	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
…		…
342		618
343	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
344	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
345	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
346	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
347	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
348		624
349	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
350	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
351	for the send to occur.	627	for the send to occur.
352		628
353	Example: wait for a timer.	629	Example: wait for a timer.
354		630
355	# wait till the result is ready	631	# condition: "wait till the timer is fired"
356	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
357		633
358	# do something such as adding a timer	634	# create the timer - we could wait for, say
359	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
360	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
361	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
362	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
363	after => 1,	639	after => 1,
364	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
365	);	641	);
366		642
367	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
368	# calls send	644	# calls ->send
369	$result_ready->recv;	645	$timer_fired->recv;
370		646
371	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
372	condition variables are also code references.	648	variables are also callable directly.
373		649
374	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
375	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
376	$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	});
377		670
378	=head3 METHODS FOR PRODUCERS	671	=head3 METHODS FOR PRODUCERS
379		672
380	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
381	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
…		…
394	immediately from within send.	687	immediately from within send.
395		688
396	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
397	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
398		691
399	Condition variables are overloaded so one can call them directly (as a	692	Condition variables are overloaded so one can call them directly (as if
400	code reference). Calling them directly is the same as calling C<send>.	693	they were a code reference). Calling them directly is the same as calling
		694	C<send>.
401		695
402	=item $cv->croak ($error)	696	=item $cv->croak ($error)
403		697
404	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
405	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
406		700
407	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
408	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.
409		707
410	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
411		709
412	=item $cv->end	710	=item $cv->end
413
414	These two methods are EXPERIMENTAL and MIGHT CHANGE.
415		711
416	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
417	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
418	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
419		715
420	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
421	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
422	>>, 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
423	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
424	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.
425		722
426	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:
427		730
428	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
429		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
430	my %result;	757	my %result;
431	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
432		759
433	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
434	$cv->begin;	761	$cv->begin;
435	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
436	$result{$host} = ...;	763	$result{$host} = ...;
…		…
451	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
452	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
453	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
454	doesn't execute once).	781	doesn't execute once).
455		782
456	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
457	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
458	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
459	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>.
460		788
461	=back	789	=back
462		790
463	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
464		792
…		…
468	=over 4	796	=over 4
469		797
470	=item $cv->recv	798	=item $cv->recv
471		799
472	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
473	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
474	normally.	802	normally.
475		803
476	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
477	will return immediately.	805	will return immediately.
478		806
…		…
480	function will call C<croak>.	808	function will call C<croak>.
481		809
482	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,
483	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
484		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
485	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
486	(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
487	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
488	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
489	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
490	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,
491	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
492		827
493	Another reason I<never> to C<< ->recv >> in a module is that you cannot
494	sensibly have two C<< ->recv >>'s in parallel, as that would require
495	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
496	can supply.
497
498	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
499	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
500	versions and also integrates coroutines into AnyEvent, making blocking
501	C<< ->recv >> calls perfectly safe as long as they are done from another
502	coroutine (one that doesn't run the event loop).
503
504	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
505	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
506	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
507	waits otherwise.	831	waits otherwise.
508		832
509	=item $bool = $cv->ready	833	=item $bool = $cv->ready
510		834
511	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
512	C<croak> have been called.	836	C<croak> have been called.
513		837
514	=item $cb = $cv->cb ([new callback])	838	=item $cb = $cv->cb ($cb->($cv))
515		839
516	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
517	replaces it before doing so.	841	replaces it before doing so.
518		842
519	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
520	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
521	or at any later time is guaranteed not to block.	847	the callback or at any later time is guaranteed not to block.
522		848
523	=back	849	=back
524		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
525	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
526		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
527	=over 4	919	=over 4
528		920
529	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
530		922
531	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
532	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
533	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
534	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
535	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
536		930	will be C<urxvt::anyevent>).
537	The known classes so far are:
538
539	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
540	AnyEvent::Impl::Event based on Event, second best choice.
541	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
542	AnyEvent::Impl::Glib based on Glib, third-best choice.
543	AnyEvent::Impl::Tk based on Tk, very bad choice.
544	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
545	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
546	AnyEvent::Impl::POE based on POE, not generic enough for full support.
547
548	There is no support for WxWidgets, as WxWidgets has no support for
549	watching file handles. However, you can use WxWidgets through the
550	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
551	second, which was considered to be too horrible to even consider for
552	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
553	it's adaptor.
554
555	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
556	autodetecting them.
557		931
558	=item AnyEvent::detect	932	=item AnyEvent::detect
559		933
560	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
561	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
562	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
563	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	If you need to do some initialisation before AnyEvent watchers are
		940	created, use C<post_detect>.
564		941
565	=item $guard = AnyEvent::post_detect { BLOCK }	942	=item $guard = AnyEvent::post_detect { BLOCK }
566		943
567	Arranges for the code block to be executed as soon as the event model is	944	Arranges for the code block to be executed as soon as the event model is
568	autodetected (or immediately if this has already happened).	945	autodetected (or immediately if that has already happened).
		946
		947	The block will be executed I<after> the actual backend has been detected
		948	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		949	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		950	other initialisations - see the sources of L<AnyEvent::Strict> or
		951	L<AnyEvent::AIO> to see how this is used.
		952
		953	The most common usage is to create some global watchers, without forcing
		954	event module detection too early, for example, L<AnyEvent::AIO> creates
		955	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		956	avoid autodetecting the event module at load time.
569		957
570	If called in scalar or list context, then it creates and returns an object	958	If called in scalar or list context, then it creates and returns an object
571	that automatically removes the callback again when it is destroyed. See	959	that automatically removes the callback again when it is destroyed (or
		960	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
572	L<Coro::BDB> for a case where this is useful.	961	a case where this is useful.
		962
		963	Example: Create a watcher for the IO::AIO module and store it in
		964	C<$WATCHER>, but do so only do so after the event loop is initialised.
		965
		966	our WATCHER;
		967
		968	my $guard = AnyEvent::post_detect {
		969	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		970	};
		971
		972	# the ||= is important in case post_detect immediately runs the block,
		973	# as to not clobber the newly-created watcher. assigning both watcher and
		974	# post_detect guard to the same variable has the advantage of users being
		975	# able to just C<undef $WATCHER> if the watcher causes them grief.
		976
		977	$WATCHER ||= $guard;
573		978
574	=item @AnyEvent::post_detect	979	=item @AnyEvent::post_detect
575		980
576	If there are any code references in this array (you can C<push> to it	981	If there are any code references in this array (you can C<push> to it
577	before or after loading AnyEvent), then they will called directly after	982	before or after loading AnyEvent), then they will be called directly
578	the event loop has been chosen.	983	after the event loop has been chosen.
579		984
580	You should check C<$AnyEvent::MODEL> before adding to this array, though:	985	You should check C<$AnyEvent::MODEL> before adding to this array, though:
581	if it contains a true value then the event loop has already been detected,	986	if it is defined then the event loop has already been detected, and the
582	and the array will be ignored.	987	array will be ignored.
583		988
584	Best use C<AnyEvent::post_detect { BLOCK }> instead.	989	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		990	it, as it takes care of these details.
		991
		992	This variable is mainly useful for modules that can do something useful
		993	when AnyEvent is used and thus want to know when it is initialised, but do
		994	not need to even load it by default. This array provides the means to hook
		995	into AnyEvent passively, without loading it.
		996
		997	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		998	together, you could put this into Coro (this is the actual code used by
		999	Coro to accomplish this):
		1000
		1001	if (defined $AnyEvent::MODEL) {
		1002	# AnyEvent already initialised, so load Coro::AnyEvent
		1003	require Coro::AnyEvent;
		1004	} else {
		1005	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1006	# as soon as it is
		1007	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1008	}
		1009
		1010	=item AnyEvent::postpone { BLOCK }
		1011
		1012	Arranges for the block to be executed as soon as possible, but not before
		1013	the call itself returns. In practise, the block will be executed just
		1014	before the event loop polls for new events, or shortly afterwards.
		1015
		1016	This function never returns anything (to make the C<return postpone { ...
		1017	}> idiom more useful.
		1018
		1019	To understand the usefulness of this function, consider a function that
		1020	asynchronously does something for you and returns some transaction
		1021	object or guard to let you cancel the operation. For example,
		1022	C<AnyEvent::Socket::tcp_connect>:
		1023
		1024	# start a conenction attempt unless one is active
		1025	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1026	delete $self->{connect_guard};
		1027	...
		1028	};
		1029
		1030	Imagine that this function could instantly call the callback, for
		1031	example, because it detects an obvious error such as a negative port
		1032	number. Invoking the callback before the function returns causes problems
		1033	however: the callback will be called and will try to delete the guard
		1034	object. But since the function hasn't returned yet, there is nothing to
		1035	delete. When the function eventually returns it will assign the guard
		1036	object to C<< $self->{connect_guard} >>, where it will likely never be
		1037	deleted, so the program thinks it is still trying to connect.
		1038
		1039	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1040	callback directly on error:
		1041
		1042	$cb->(undef), return # signal error to callback, BAD!
		1043	if $some_error_condition;
		1044
		1045	It should use C<postpone>:
		1046
		1047	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1048	if $some_error_condition;
585		1049
586	=back	1050	=back
587		1051
588	=head1 WHAT TO DO IN A MODULE	1052	=head1 WHAT TO DO IN A MODULE
589		1053
…		…
600	because it will stall the whole program, and the whole point of using	1064	because it will stall the whole program, and the whole point of using
601	events is to stay interactive.	1065	events is to stay interactive.
602		1066
603	It is fine, however, to call C<< ->recv >> when the user of your module	1067	It is fine, however, to call C<< ->recv >> when the user of your module
604	requests it (i.e. if you create a http request object ad have a method	1068	requests it (i.e. if you create a http request object ad have a method
605	called C<results> that returns the results, it should call C<< ->recv >>	1069	called C<results> that returns the results, it may call C<< ->recv >>
606	freely, as the user of your module knows what she is doing. always).	1070	freely, as the user of your module knows what she is doing. Always).
607		1071
608	=head1 WHAT TO DO IN THE MAIN PROGRAM	1072	=head1 WHAT TO DO IN THE MAIN PROGRAM
609		1073
610	There will always be a single main program - the only place that should	1074	There will always be a single main program - the only place that should
611	dictate which event model to use.	1075	dictate which event model to use.
612		1076
613	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1077	If the program is not event-based, it need not do anything special, even
614	do anything special (it does not need to be event-based) and let AnyEvent	1078	when it depends on a module that uses an AnyEvent. If the program itself
615	decide which implementation to chose if some module relies on it.	1079	uses AnyEvent, but does not care which event loop is used, all it needs
		1080	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1081	available loop implementation.
616		1082
617	If the main program relies on a specific event model. For example, in	1083	If the main program relies on a specific event model - for example, in
618	Gtk2 programs you have to rely on the Glib module. You should load the	1084	Gtk2 programs you have to rely on the Glib module - you should load the
619	event module before loading AnyEvent or any module that uses it: generally	1085	event module before loading AnyEvent or any module that uses it: generally
620	speaking, you should load it as early as possible. The reason is that	1086	speaking, you should load it as early as possible. The reason is that
621	modules might create watchers when they are loaded, and AnyEvent will	1087	modules might create watchers when they are loaded, and AnyEvent will
622	decide on the event model to use as soon as it creates watchers, and it	1088	decide on the event model to use as soon as it creates watchers, and it
623	might chose the wrong one unless you load the correct one yourself.	1089	might choose the wrong one unless you load the correct one yourself.
624		1090
625	You can chose to use a rather inefficient pure-perl implementation by	1091	You can chose to use a pure-perl implementation by loading the
626	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	1092	C<AnyEvent::Loop> module, which gives you similar behaviour
627	behaviour everywhere, but letting AnyEvent chose is generally better.	1093	everywhere, but letting AnyEvent chose the model is generally better.
		1094
		1095	=head2 MAINLOOP EMULATION
		1096
		1097	Sometimes (often for short test scripts, or even standalone programs who
		1098	only want to use AnyEvent), you do not want to run a specific event loop.
		1099
		1100	In that case, you can use a condition variable like this:
		1101
		1102	AnyEvent->condvar->recv;
		1103
		1104	This has the effect of entering the event loop and looping forever.
		1105
		1106	Note that usually your program has some exit condition, in which case
		1107	it is better to use the "traditional" approach of storing a condition
		1108	variable somewhere, waiting for it, and sending it when the program should
		1109	exit cleanly.
		1110
628		1111
629	=head1 OTHER MODULES	1112	=head1 OTHER MODULES
630		1113
631	The following is a non-exhaustive list of additional modules that use	1114	The following is a non-exhaustive list of additional modules that use
632	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1115	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
633	in the same program. Some of the modules come with AnyEvent, some are	1116	modules and other event loops in the same program. Some of the modules
634	available via CPAN.	1117	come as part of AnyEvent, the others are available via CPAN.
635		1118
636	=over 4	1119	=over 4
637		1120
638	=item L<AnyEvent::Util>	1121	=item L<AnyEvent::Util>
639		1122
640	Contains various utility functions that replace often-used but blocking	1123	Contains various utility functions that replace often-used blocking
641	functions such as C<inet_aton> by event-/callback-based versions.	1124	functions such as C<inet_aton> with event/callback-based versions.
642
643	=item L<AnyEvent::Handle>
644
645	Provide read and write buffers and manages watchers for reads and writes.
646		1125
647	=item L<AnyEvent::Socket>	1126	=item L<AnyEvent::Socket>
648		1127
649	Provides various utility functions for (internet protocol) sockets,	1128	Provides various utility functions for (internet protocol) sockets,
650	addresses and name resolution. Also functions to create non-blocking tcp	1129	addresses and name resolution. Also functions to create non-blocking tcp
651	connections or tcp servers, with IPv6 and SRV record support and more.	1130	connections or tcp servers, with IPv6 and SRV record support and more.
652		1131
		1132	=item L<AnyEvent::Handle>
		1133
		1134	Provide read and write buffers, manages watchers for reads and writes,
		1135	supports raw and formatted I/O, I/O queued and fully transparent and
		1136	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
		1137
		1138	=item L<AnyEvent::DNS>
		1139
		1140	Provides rich asynchronous DNS resolver capabilities.
		1141
		1142	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1143
		1144	Implement event-based interfaces to the protocols of the same name (for
		1145	the curious, IGS is the International Go Server and FCP is the Freenet
		1146	Client Protocol).
		1147
		1148	=item L<AnyEvent::Handle::UDP>
		1149
		1150	Here be danger!
		1151
		1152	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1153	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1154	its use of a stream-based API with a protocol that isn't streamable, that
		1155	the only way to improve it is to delete it.
		1156
		1157	It features data corruption (but typically only under load) and general
		1158	confusion. On top, the author is not only clueless about UDP but also
		1159	fact-resistant - some gems of his understanding: "connect doesn't work
		1160	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1161	packets", "I don't need to implement proper error checking as UDP doesn't
		1162	support error checking" and so on - he doesn't even understand what's
		1163	wrong with his module when it is explained to him.
		1164
		1165	=item L<AnyEvent::DBI>
		1166
		1167	Executes L<DBI> requests asynchronously in a proxy process for you,
		1168	notifying you in an event-based way when the operation is finished.
		1169
		1170	=item L<AnyEvent::AIO>
		1171
		1172	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1173	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1174	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1175	file I/O, and much more.
		1176
653	=item L<AnyEvent::HTTPD>	1177	=item L<AnyEvent::HTTPD>
654		1178
655	Provides a simple web application server framework.	1179	A simple embedded webserver.
656
657	=item L<AnyEvent::DNS>
658
659	Provides rich asynchronous DNS resolver capabilities.
660		1180
661	=item L<AnyEvent::FastPing>	1181	=item L<AnyEvent::FastPing>
662		1182
663	The fastest ping in the west.	1183	The fastest ping in the west.
664		1184
665	=item L<Net::IRC3>
666
667	AnyEvent based IRC client module family.
668
669	=item L<Net::XMPP2>
670
671	AnyEvent based XMPP (Jabber protocol) module family.
672
673	=item L<Net::FCP>
674
675	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
676	of AnyEvent.
677
678	=item L<Event::ExecFlow>
679
680	High level API for event-based execution flow control.
681
682	=item L<Coro>	1185	=item L<Coro>
683		1186
684	Has special support for AnyEvent via L<Coro::AnyEvent>.	1187	Has special support for AnyEvent via L<Coro::AnyEvent>.
685		1188
686	=item L<AnyEvent::AIO>, L<IO::AIO>
687
688	Truly asynchronous I/O, should be in the toolbox of every event
689	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
690	together.
691
692	=item L<AnyEvent::BDB>, L<BDB>
693
694	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
695	IO::AIO and AnyEvent together.
696
697	=item L<IO::Lambda>
698
699	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
700
701	=back	1189	=back
702		1190
703	=cut	1191	=cut
704		1192
705	package AnyEvent;	1193	package AnyEvent;
706		1194
707	no warnings;	1195	# basically a tuned-down version of common::sense
708	use strict;	1196	sub common_sense {
		1197	# from common:.sense 3.4
		1198	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1199	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1200	$^H |= 0x00000600;
		1201	}
709		1202
		1203	BEGIN { AnyEvent::common_sense }
		1204
710	use Carp;	1205	use Carp ();
711		1206
712	our $VERSION = '4.0';	1207	our $VERSION = '5.34';
713	our $MODEL;	1208	our $MODEL;
714		1209
715	our $AUTOLOAD;
716	our @ISA;	1210	our @ISA;
717		1211
718	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
719
720	our @REGISTRY;	1212	our @REGISTRY;
721		1213
722	our %PROTOCOL; # (ipv4|ipv6) => (1|2)	1214	our $VERBOSE;
		1215
		1216	BEGIN {
		1217	require "AnyEvent/constants.pl";
		1218
		1219	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1220
		1221	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1222	if ${^TAINT};
		1223
		1224	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1225
		1226	}
		1227
		1228	our $MAX_SIGNAL_LATENCY = 10;
		1229
		1230	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
723		1231
724	{	1232	{
725	my $idx;	1233	my $idx;
726	$PROTOCOL{$_} = ++$idx	1234	$PROTOCOL{$_} = ++$idx
		1235	for reverse split /\s*,\s*/,
727	for split /\s*,\s*/, $ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1236	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
728	}	1237	}
729		1238
		1239	our @post_detect;
		1240
		1241	sub post_detect(&) {
		1242	my ($cb) = @_;
		1243
		1244	push @post_detect, $cb;
		1245
		1246	defined wantarray
		1247	? bless \$cb, "AnyEvent::Util::postdetect"
		1248	: ()
		1249	}
		1250
		1251	sub AnyEvent::Util::postdetect::DESTROY {
		1252	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1253	}
		1254
		1255	our $POSTPONE_W;
		1256	our @POSTPONE;
		1257
		1258	sub _postpone_exec {
		1259	undef $POSTPONE_W;
		1260
		1261	&{ shift @POSTPONE }
		1262	while @POSTPONE;
		1263	}
		1264
		1265	sub postpone(&) {
		1266	push @POSTPONE, shift;
		1267
		1268	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1269
		1270	()
		1271	}
		1272
730	my @models = (	1273	our @models = (
731	[EV:: => AnyEvent::Impl::EV::],	1274	[EV:: => AnyEvent::Impl::EV:: , 1],
		1275	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
		1276	# everything below here will not (normally) be autoprobed
		1277	# as the pure perl backend should work everywhere
		1278	# and is usually faster
732	[Event:: => AnyEvent::Impl::Event::],	1279	[Event:: => AnyEvent::Impl::Event::, 1],
		1280	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1281	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1282	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
733	[Tk:: => AnyEvent::Impl::Tk::],	1283	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1284	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1285	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
734	[Wx:: => AnyEvent::Impl::POE::],	1286	[Wx:: => AnyEvent::Impl::POE::],
735	[Prima:: => AnyEvent::Impl::POE::],	1287	[Prima:: => AnyEvent::Impl::POE::],
736	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1288	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
737	# everything below here will not be autoprobed as the pureperl backend should work everywhere	1289	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
738	[Glib:: => AnyEvent::Impl::Glib::],	1290	[FLTK:: => AnyEvent::Impl::FLTK2::],
739	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
740	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
741	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
742	);	1291	);
743		1292
744	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	1293	# all autoloaded methods reserve the complete glob, not just the method slot.
		1294	# due to bugs in perls method cache implementation.
		1295	our @methods = qw(io timer time now now_update signal child idle condvar);
745		1296
746	our @post_detect;
747
748	sub post_detect(&) {	1297	sub detect() {
749	my ($cb) = @_;	1298	local $!; # for good measure
		1299	local $SIG{__DIE__}; # we use eval
750		1300
751	if ($MODEL) {	1301	# free some memory
752	$cb->();	1302	*detect = sub () { $MODEL };
		1303	# undef &func doesn't correctly update the method cache. grmbl.
		1304	# so we delete the whole glob. grmbl.
		1305	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1306	# a glob with an active sub. hrm. i hope it works, but perl is
		1307	# usually buggy in this department. sigh.
		1308	delete @{"AnyEvent::"}{@methods};
		1309	undef @methods;
753		1310
754	1	1311	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1312	my $model = $1;
		1313	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1314	if (eval "require $model") {
		1315	$MODEL = $model;
		1316	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
755	} else {	1317	} else {
756	push @post_detect, $cb;	1318	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
757		1319	}
758	defined wantarray
759	? bless \$cb, "AnyEvent::Util::PostDetect"
760	: ()
761	}	1320	}
762	}
763		1321
764	sub AnyEvent::Util::PostDetect::DESTROY {	1322	# check for already loaded models
765	@post_detect = grep $_ != ${$_[0]}, @post_detect;
766	}
767
768	sub detect() {
769	unless ($MODEL) {	1323	unless ($MODEL) {
770	no strict 'refs';	1324	for (@REGISTRY, @models) {
771		1325	my ($package, $model) = @$_;
772	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1326	if (${"$package\::VERSION"} > 0) {
773	my $model = "AnyEvent::Impl::$1";
774	if (eval "require $model") {	1327	if (eval "require $model") {
775	$MODEL = $model;	1328	$MODEL = $model;
776	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1329	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
777	} else {	1330	last;
778	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1331	}
779	}	1332	}
780	}	1333	}
781		1334
782	# check for already loaded models
783	unless ($MODEL) {	1335	unless ($MODEL) {
		1336	# try to autoload a model
784	for (@REGISTRY, @models) {	1337	for (@REGISTRY, @models) {
785	my ($package, $model) = @$_;	1338	my ($package, $model, $autoload) = @$_;
		1339	if (
		1340	$autoload
		1341	and eval "require $package"
786	if (${"$package\::VERSION"} > 0) {	1342	and ${"$package\::VERSION"} > 0
787	if (eval "require $model") {	1343	and eval "require $model"
		1344	) {
788	$MODEL = $model;	1345	$MODEL = $model;
789	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1346	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
790	last;	1347	last;
791	}
792	}	1348	}
793	}	1349	}
794		1350
795	unless ($MODEL) {	1351	$MODEL
796	# try to load a model	1352	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?\n";
		1353	}
		1354	}
797		1355
798	for (@REGISTRY, @models) {	1356	# free memory only needed for probing
799	my ($package, $model) = @$_;	1357	undef @models;
800	if (eval "require $package"	1358	undef @REGISTRY;
801	and ${"$package\::VERSION"} > 0	1359
802	and eval "require $model") {	1360	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
803	$MODEL = $model;	1361	unshift @ISA, $MODEL;
804	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1362
		1363	# now nuke some methods that are overridden by the backend.
		1364	# SUPER usage is not allowed in these.
		1365	for (qw(time signal child idle)) {
		1366	undef &{"AnyEvent::Base::$_"}
		1367	if defined &{"$MODEL\::$_"};
		1368	}
		1369
		1370	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1371	require AnyEvent::Strict;
		1372	}
		1373
		1374	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1375	require AnyEvent::Debug;
		1376	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1377	}
		1378
		1379	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1380	require AnyEvent::Socket;
		1381	require AnyEvent::Debug;
		1382
		1383	my ($host, $service) = AnyEvent::Socket::parse_hostport ($ENV{PERL_ANYEVENT_DEBUG_SHELL});
		1384	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1385	}
		1386
		1387	(shift @post_detect)->() while @post_detect;
		1388	undef @post_detect;
		1389
		1390	*post_detect = sub(&) {
		1391	shift->();
		1392
		1393	undef
		1394	};
		1395
		1396	$MODEL
		1397	}
		1398
		1399	for my $name (@methods) {
		1400	*$name = sub {
		1401	detect;
		1402	# we use goto because
		1403	# a) it makes the thunk more transparent
		1404	# b) it allows us to delete the thunk later
		1405	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
		1406	};
		1407	}
		1408
		1409	# utility function to dup a filehandle. this is used by many backends
		1410	# to support binding more than one watcher per filehandle (they usually
		1411	# allow only one watcher per fd, so we dup it to get a different one).
		1412	sub _dupfh($$;$$) {
		1413	my ($poll, $fh, $r, $w) = @_;
		1414
		1415	# cygwin requires the fh mode to be matching, unix doesn't
		1416	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1417
		1418	open my $fh2, $mode, $fh
		1419	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1420
		1421	# we assume CLOEXEC is already set by perl in all important cases
		1422
		1423	($fh2, $rw)
		1424	}
		1425
		1426	=head1 SIMPLIFIED AE API
		1427
		1428	Starting with version 5.0, AnyEvent officially supports a second, much
		1429	simpler, API that is designed to reduce the calling, typing and memory
		1430	overhead by using function call syntax and a fixed number of parameters.
		1431
		1432	See the L<AE> manpage for details.
		1433
		1434	=cut
		1435
		1436	package AE;
		1437
		1438	our $VERSION = $AnyEvent::VERSION;
		1439
		1440	sub _reset() {
		1441	eval q{
		1442	# fall back to the main API by default - backends and AnyEvent::Base
		1443	# implementations can overwrite these.
		1444
		1445	sub io($$$) {
		1446	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1447	}
		1448
		1449	sub timer($$$) {
		1450	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1451	}
		1452
		1453	sub signal($$) {
		1454	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1455	}
		1456
		1457	sub child($$) {
		1458	AnyEvent->child (pid => $_[0], cb => $_[1])
		1459	}
		1460
		1461	sub idle($) {
		1462	AnyEvent->idle (cb => $_[0]);
		1463	}
		1464
		1465	sub cv(;&) {
		1466	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1467	}
		1468
		1469	sub now() {
		1470	AnyEvent->now
		1471	}
		1472
		1473	sub now_update() {
		1474	AnyEvent->now_update
		1475	}
		1476
		1477	sub time() {
		1478	AnyEvent->time
		1479	}
		1480
		1481	*postpone = \&AnyEvent::postpone;
		1482	};
		1483	die if $@;
		1484	}
		1485
		1486	BEGIN { _reset }
		1487
		1488	package AnyEvent::Base;
		1489
		1490	# default implementations for many methods
		1491
		1492	sub time {
		1493	eval q{ # poor man's autoloading {}
		1494	# probe for availability of Time::HiRes
		1495	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1496	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1497	*AE::time = \&Time::HiRes::time;
		1498	# if (eval "use POSIX (); (POSIX::times())...
		1499	} else {
		1500	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1501	*AE::time = sub (){ time }; # epic fail
		1502	}
		1503
		1504	*time = sub { AE::time }; # different prototypes
		1505	};
		1506	die if $@;
		1507
		1508	&time
		1509	}
		1510
		1511	*now = \&time;
		1512
		1513	sub now_update { }
		1514
		1515	sub _poll {
		1516	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1517	}
		1518
		1519	# default implementation for ->condvar
		1520	# in fact, the default should not be overwritten
		1521
		1522	sub condvar {
		1523	eval q{ # poor man's autoloading {}
		1524	*condvar = sub {
		1525	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1526	};
		1527
		1528	*AE::cv = sub (;&) {
		1529	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1530	};
		1531	};
		1532	die if $@;
		1533
		1534	&condvar
		1535	}
		1536
		1537	# default implementation for ->signal
		1538
		1539	our $HAVE_ASYNC_INTERRUPT;
		1540
		1541	sub _have_async_interrupt() {
		1542	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1543	&& eval "use Async::Interrupt 1.02 (); 1")
		1544	unless defined $HAVE_ASYNC_INTERRUPT;
		1545
		1546	$HAVE_ASYNC_INTERRUPT
		1547	}
		1548
		1549	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1550	our (%SIG_ASY, %SIG_ASY_W);
		1551	our ($SIG_COUNT, $SIG_TW);
		1552
		1553	# install a dummy wakeup watcher to reduce signal catching latency
		1554	# used by Impls
		1555	sub _sig_add() {
		1556	unless ($SIG_COUNT++) {
		1557	# try to align timer on a full-second boundary, if possible
		1558	my $NOW = AE::now;
		1559
		1560	$SIG_TW = AE::timer
		1561	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1562	$MAX_SIGNAL_LATENCY,
		1563	sub { } # just for the PERL_ASYNC_CHECK
		1564	;
		1565	}
		1566	}
		1567
		1568	sub _sig_del {
		1569	undef $SIG_TW
		1570	unless --$SIG_COUNT;
		1571	}
		1572
		1573	our $_sig_name_init; $_sig_name_init = sub {
		1574	eval q{ # poor man's autoloading {}
		1575	undef $_sig_name_init;
		1576
		1577	if (_have_async_interrupt) {
		1578	*sig2num = \&Async::Interrupt::sig2num;
		1579	*sig2name = \&Async::Interrupt::sig2name;
		1580	} else {
		1581	require Config;
		1582
		1583	my %signame2num;
		1584	@signame2num{ split ' ', $Config::Config{sig_name} }
		1585	= split ' ', $Config::Config{sig_num};
		1586
		1587	my @signum2name;
		1588	@signum2name[values %signame2num] = keys %signame2num;
		1589
		1590	*sig2num = sub($) {
		1591	$_[0] > 0 ? shift : $signame2num{+shift}
		1592	};
		1593	*sig2name = sub ($) {
		1594	$_[0] > 0 ? $signum2name[+shift] : shift
		1595	};
		1596	}
		1597	};
		1598	die if $@;
		1599	};
		1600
		1601	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1602	sub sig2name($) { &$_sig_name_init; &sig2name }
		1603
		1604	sub signal {
		1605	eval q{ # poor man's autoloading {}
		1606	# probe for availability of Async::Interrupt
		1607	if (_have_async_interrupt) {
		1608	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1609
		1610	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1611	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1612
		1613	} else {
		1614	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1615
		1616	if (AnyEvent::WIN32) {
		1617	require AnyEvent::Util;
		1618
		1619	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1620	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1621	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1622	} else {
		1623	pipe $SIGPIPE_R, $SIGPIPE_W;
		1624	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1625	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1626
		1627	# not strictly required, as $^F is normally 2, but let's make sure...
		1628	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1629	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1630	}
		1631
		1632	$SIGPIPE_R
		1633	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1634
		1635	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1636	}
		1637
		1638	*signal = $HAVE_ASYNC_INTERRUPT
		1639	? sub {
		1640	my (undef, %arg) = @_;
		1641
		1642	# async::interrupt
		1643	my $signal = sig2num $arg{signal};
		1644	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1645
		1646	$SIG_ASY{$signal} ||= new Async::Interrupt
		1647	cb => sub { undef $SIG_EV{$signal} },
		1648	signal => $signal,
		1649	pipe => [$SIGPIPE_R->filenos],
		1650	pipe_autodrain => 0,
		1651	;
		1652
		1653	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1654	}
		1655	: sub {
		1656	my (undef, %arg) = @_;
		1657
		1658	# pure perl
		1659	my $signal = sig2name $arg{signal};
		1660	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1661
		1662	$SIG{$signal} ||= sub {
805	last;	1663	local $!;
		1664	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1665	undef $SIG_EV{$signal};
806	}	1666	};
		1667
		1668	# can't do signal processing without introducing races in pure perl,
		1669	# so limit the signal latency.
		1670	_sig_add;
		1671
		1672	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1673	}
		1674	;
		1675
		1676	*AnyEvent::Base::signal::DESTROY = sub {
		1677	my ($signal, $cb) = @{$_[0]};
		1678
		1679	_sig_del;
		1680
		1681	delete $SIG_CB{$signal}{$cb};
		1682
		1683	$HAVE_ASYNC_INTERRUPT
		1684	? delete $SIG_ASY{$signal}
		1685	: # delete doesn't work with older perls - they then
		1686	# print weird messages, or just unconditionally exit
		1687	# instead of getting the default action.
		1688	undef $SIG{$signal}
		1689	unless keys %{ $SIG_CB{$signal} };
		1690	};
		1691
		1692	*_signal_exec = sub {
		1693	$HAVE_ASYNC_INTERRUPT
		1694	? $SIGPIPE_R->drain
		1695	: sysread $SIGPIPE_R, (my $dummy), 9;
		1696
		1697	while (%SIG_EV) {
		1698	for (keys %SIG_EV) {
		1699	delete $SIG_EV{$_};
		1700	&$_ for values %{ $SIG_CB{$_} || {} };
807	}	1701	}
808
809	$MODEL
810	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
811	}	1702	}
812	}	1703	};
813
814	unshift @ISA, $MODEL;
815	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
816
817	(shift @post_detect)->() while @post_detect;
818	}
819
820	$MODEL
821	}
822
823	sub AUTOLOAD {
824	(my $func = $AUTOLOAD) =~ s/.*://;
825
826	$method{$func}
827	or croak "$func: not a valid method for AnyEvent objects";
828
829	detect unless $MODEL;
830
831	my $class = shift;
832	$class->$func (@_);
833	}
834
835	package AnyEvent::Base;
836
837	# default implementation for ->condvar
838
839	sub condvar {
840	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
841	}
842
843	# default implementation for ->signal
844
845	our %SIG_CB;
846
847	sub signal {
848	my (undef, %arg) = @_;
849
850	my $signal = uc $arg{signal}
851	or Carp::croak "required option 'signal' is missing";
852
853	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
854	$SIG{$signal} ||= sub {
855	$_->() for values %{ $SIG_CB{$signal} || {} };
856	};	1704	};
		1705	die if $@;
857		1706
858	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1707	&signal
859	}
860
861	sub AnyEvent::Base::Signal::DESTROY {
862	my ($signal, $cb) = @{$_[0]};
863
864	delete $SIG_CB{$signal}{$cb};
865
866	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
867	}	1708	}
868		1709
869	# default implementation for ->child	1710	# default implementation for ->child
870		1711
871	our %PID_CB;	1712	our %PID_CB;
872	our $CHLD_W;	1713	our $CHLD_W;
873	our $CHLD_DELAY_W;	1714	our $CHLD_DELAY_W;
874	our $PID_IDLE;
875	our $WNOHANG;
876		1715
877	sub _child_wait {	1716	# used by many Impl's
878	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1717	sub _emit_childstatus($$) {
		1718	my (undef, $rpid, $rstatus) = @_;
		1719
		1720	$_->($rpid, $rstatus)
879	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1721	for values %{ $PID_CB{$rpid} || {} },
880	(values %{ $PID_CB{0} || {} });	1722	values %{ $PID_CB{0} || {} };
881	}
882
883	undef $PID_IDLE;
884	}
885
886	sub _sigchld {
887	# make sure we deliver these changes "synchronous" with the event loop.
888	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
889	undef $CHLD_DELAY_W;
890	&_child_wait;
891	});
892	}	1723	}
893		1724
894	sub child {	1725	sub child {
		1726	eval q{ # poor man's autoloading {}
		1727	*_sigchld = sub {
		1728	my $pid;
		1729
		1730	AnyEvent->_emit_childstatus ($pid, $?)
		1731	while ($pid = waitpid -1, WNOHANG) > 0;
		1732	};
		1733
		1734	*child = sub {
895	my (undef, %arg) = @_;	1735	my (undef, %arg) = @_;
896		1736
897	defined (my $pid = $arg{pid} + 0)	1737	my $pid = $arg{pid};
898	or Carp::croak "required option 'pid' is missing";	1738	my $cb = $arg{cb};
899		1739
900	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1740	$PID_CB{$pid}{$cb+0} = $cb;
901		1741
902	unless ($WNOHANG) {
903	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;
904	}
905
906	unless ($CHLD_W) {	1742	unless ($CHLD_W) {
907	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1743	$CHLD_W = AE::signal CHLD => \&_sigchld;
908	# child could be a zombie already, so make at least one round	1744	# child could be a zombie already, so make at least one round
909	&_sigchld;	1745	&_sigchld;
910	}	1746	}
911		1747
912	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1748	bless [$pid, $cb+0], "AnyEvent::Base::child"
913	}	1749	};
914		1750
915	sub AnyEvent::Base::Child::DESTROY {	1751	*AnyEvent::Base::child::DESTROY = sub {
916	my ($pid, $cb) = @{$_[0]};	1752	my ($pid, $icb) = @{$_[0]};
917		1753
918	delete $PID_CB{$pid}{$cb};	1754	delete $PID_CB{$pid}{$icb};
919	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1755	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
920		1756
921	undef $CHLD_W unless keys %PID_CB;	1757	undef $CHLD_W unless keys %PID_CB;
		1758	};
		1759	};
		1760	die if $@;
		1761
		1762	&child
		1763	}
		1764
		1765	# idle emulation is done by simply using a timer, regardless
		1766	# of whether the process is idle or not, and not letting
		1767	# the callback use more than 50% of the time.
		1768	sub idle {
		1769	eval q{ # poor man's autoloading {}
		1770	*idle = sub {
		1771	my (undef, %arg) = @_;
		1772
		1773	my ($cb, $w, $rcb) = $arg{cb};
		1774
		1775	$rcb = sub {
		1776	if ($cb) {
		1777	$w = AE::time;
		1778	&$cb;
		1779	$w = AE::time - $w;
		1780
		1781	# never use more then 50% of the time for the idle watcher,
		1782	# within some limits
		1783	$w = 0.0001 if $w < 0.0001;
		1784	$w = 5 if $w > 5;
		1785
		1786	$w = AE::timer $w, 0, $rcb;
		1787	} else {
		1788	# clean up...
		1789	undef $w;
		1790	undef $rcb;
		1791	}
		1792	};
		1793
		1794	$w = AE::timer 0.05, 0, $rcb;
		1795
		1796	bless \\$cb, "AnyEvent::Base::idle"
		1797	};
		1798
		1799	*AnyEvent::Base::idle::DESTROY = sub {
		1800	undef $${$_[0]};
		1801	};
		1802	};
		1803	die if $@;
		1804
		1805	&idle
922	}	1806	}
923		1807
924	package AnyEvent::CondVar;	1808	package AnyEvent::CondVar;
925		1809
926	our @ISA = AnyEvent::CondVar::Base::;	1810	our @ISA = AnyEvent::CondVar::Base::;
927		1811
		1812	# only to be used for subclassing
		1813	sub new {
		1814	my $class = shift;
		1815	bless AnyEvent->condvar (@_), $class
		1816	}
		1817
928	package AnyEvent::CondVar::Base;	1818	package AnyEvent::CondVar::Base;
929		1819
930	use overload	1820	#use overload
931	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1821	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
932	fallback => 1;	1822	# fallback => 1;
		1823
		1824	# save 300+ kilobytes by dirtily hardcoding overloading
		1825	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1826	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1827	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1828	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1829
		1830	our $WAITING;
933		1831
934	sub _send {	1832	sub _send {
935	# nop	1833	# nop
		1834	}
		1835
		1836	sub _wait {
		1837	AnyEvent->_poll until $_[0]{_ae_sent};
936	}	1838	}
937		1839
938	sub send {	1840	sub send {
939	my $cv = shift;	1841	my $cv = shift;
940	$cv->{_ae_sent} = [@_];	1842	$cv->{_ae_sent} = [@_];
…		…
949		1851
950	sub ready {	1852	sub ready {
951	$_[0]{_ae_sent}	1853	$_[0]{_ae_sent}
952	}	1854	}
953		1855
954	sub _wait {
955	AnyEvent->one_event while !$_[0]{_ae_sent};
956	}
957
958	sub recv {	1856	sub recv {
		1857	unless ($_[0]{_ae_sent}) {
		1858	$WAITING
		1859	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1860
		1861	local $WAITING = 1;
959	$_[0]->_wait;	1862	$_[0]->_wait;
		1863	}
960		1864
961	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1865	$_[0]{_ae_croak}
962	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1866	and Carp::croak $_[0]{_ae_croak};
		1867
		1868	wantarray
		1869	? @{ $_[0]{_ae_sent} }
		1870	: $_[0]{_ae_sent}[0]
963	}	1871	}
964		1872
965	sub cb {	1873	sub cb {
966	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1874	my $cv = shift;
		1875
		1876	@_
		1877	and $cv->{_ae_cb} = shift
		1878	and $cv->{_ae_sent}
		1879	and (delete $cv->{_ae_cb})->($cv);
		1880
967	$_[0]{_ae_cb}	1881	$cv->{_ae_cb}
968	}	1882	}
969		1883
970	sub begin {	1884	sub begin {
971	++$_[0]{_ae_counter};	1885	++$_[0]{_ae_counter};
972	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1886	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
977	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1891	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
978	}	1892	}
979		1893
980	# undocumented/compatibility with pre-3.4	1894	# undocumented/compatibility with pre-3.4
981	*broadcast = \&send;	1895	*broadcast = \&send;
982	*wait = \&_wait;	1896	*wait = \&recv;
		1897
		1898	=head1 ERROR AND EXCEPTION HANDLING
		1899
		1900	In general, AnyEvent does not do any error handling - it relies on the
		1901	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1902	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1903	checking of all AnyEvent methods, however, which is highly useful during
		1904	development.
		1905
		1906	As for exception handling (i.e. runtime errors and exceptions thrown while
		1907	executing a callback), this is not only highly event-loop specific, but
		1908	also not in any way wrapped by this module, as this is the job of the main
		1909	program.
		1910
		1911	The pure perl event loop simply re-throws the exception (usually
		1912	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1913	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1914	so on.
		1915
		1916	=head1 ENVIRONMENT VARIABLES
		1917
		1918	The following environment variables are used by this module or its
		1919	submodules.
		1920
		1921	Note that AnyEvent will remove I<all> environment variables starting with
		1922	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1923	enabled.
		1924
		1925	=over 4
		1926
		1927	=item C<PERL_ANYEVENT_VERBOSE>
		1928
		1929	By default, AnyEvent will be completely silent except in fatal
		1930	conditions. You can set this environment variable to make AnyEvent more
		1931	talkative.
		1932
		1933	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1934	conditions, such as not being able to load the event model specified by
		1935	C<PERL_ANYEVENT_MODEL>.
		1936
		1937	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1938	model it chooses.
		1939
		1940	When set to C<8> or higher, then AnyEvent will report extra information on
		1941	which optional modules it loads and how it implements certain features.
		1942
		1943	=item C<PERL_ANYEVENT_STRICT>
		1944
		1945	AnyEvent does not do much argument checking by default, as thorough
		1946	argument checking is very costly. Setting this variable to a true value
		1947	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1948	check the arguments passed to most method calls. If it finds any problems,
		1949	it will croak.
		1950
		1951	In other words, enables "strict" mode.
		1952
		1953	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
		1954	>>, it is definitely recommended to keep it off in production. Keeping
		1955	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1956	can be very useful, however.
		1957
		1958	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		1959
		1960	If this env variable is set, then its contents will be
		1961	interpreted by C<AnyEvent::Socket::parse_hostport> and an
		1962	C<AnyEvent::Debug::shell> is bound on that port. The shell object is saved
		1963	in C<$AnyEvent::Debug::SHELL>.
		1964
		1965	For example, to bind a debug shell on a unix domain socket in
		1966	F</tmp/debug.sock>, you could use this:
		1967
		1968	PERL_ANYEVENT_DEBUG_SHELL=unix/:/tmp/debug.sock perlprog
		1969
		1970	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		1971
		1972	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		1973	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
		1974
		1975	=item C<PERL_ANYEVENT_MODEL>
		1976
		1977	This can be used to specify the event model to be used by AnyEvent, before
		1978	auto detection and -probing kicks in.
		1979
		1980	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		1981	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
		1982	resulting module name is loaded and - if the load was successful - used as
		1983	event model backend. If it fails to load then AnyEvent will proceed with
		1984	auto detection and -probing.
		1985
		1986	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		1987	nothing gets prepended and the module name is used as-is (hint: C<::> at
		1988	the end of a string designates a module name and quotes it appropriately).
		1989
		1990	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
		1991	could start your program like this:
		1992
		1993	PERL_ANYEVENT_MODEL=Perl perl ...
		1994
		1995	=item C<PERL_ANYEVENT_PROTOCOLS>
		1996
		1997	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1998	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1999	of auto probing).
		2000
		2001	Must be set to a comma-separated list of protocols or address families,
		2002	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		2003	used, and preference will be given to protocols mentioned earlier in the
		2004	list.
		2005
		2006	This variable can effectively be used for denial-of-service attacks
		2007	against local programs (e.g. when setuid), although the impact is likely
		2008	small, as the program has to handle conenction and other failures anyways.
		2009
		2010	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		2011	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		2012	- only support IPv4, never try to resolve or contact IPv6
		2013	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		2014	IPv6, but prefer IPv6 over IPv4.
		2015
		2016	=item C<PERL_ANYEVENT_EDNS0>
		2017
		2018	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		2019	for DNS. This extension is generally useful to reduce DNS traffic, but
		2020	some (broken) firewalls drop such DNS packets, which is why it is off by
		2021	default.
		2022
		2023	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		2024	EDNS0 in its DNS requests.
		2025
		2026	=item C<PERL_ANYEVENT_MAX_FORKS>
		2027
		2028	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		2029	will create in parallel.
		2030
		2031	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2032
		2033	The default value for the C<max_outstanding> parameter for the default DNS
		2034	resolver - this is the maximum number of parallel DNS requests that are
		2035	sent to the DNS server.
		2036
		2037	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2038
		2039	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2040	configuration) in the default resolver. When set to the empty string, no
		2041	default config will be used.
		2042
		2043	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2044
		2045	When neither C<ca_file> nor C<ca_path> was specified during
		2046	L<AnyEvent::TLS> context creation, and either of these environment
		2047	variables exist, they will be used to specify CA certificate locations
		2048	instead of a system-dependent default.
		2049
		2050	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2051
		2052	When these are set to C<1>, then the respective modules are not
		2053	loaded. Mostly good for testing AnyEvent itself.
		2054
		2055	=back
983		2056
984	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2057	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
985		2058
986	This is an advanced topic that you do not normally need to use AnyEvent in	2059	This is an advanced topic that you do not normally need to use AnyEvent in
987	a module. This section is only of use to event loop authors who want to	2060	a module. This section is only of use to event loop authors who want to
…		…
1021		2094
1022	I<rxvt-unicode> also cheats a bit by not providing blocking access to	2095	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1023	condition variables: code blocking while waiting for a condition will	2096	condition variables: code blocking while waiting for a condition will
1024	C<die>. This still works with most modules/usages, and blocking calls must	2097	C<die>. This still works with most modules/usages, and blocking calls must
1025	not be done in an interactive application, so it makes sense.	2098	not be done in an interactive application, so it makes sense.
1026
1027	=head1 ENVIRONMENT VARIABLES
1028
1029	The following environment variables are used by this module:
1030
1031	=over 4
1032
1033	=item C<PERL_ANYEVENT_VERBOSE>
1034
1035	By default, AnyEvent will be completely silent except in fatal
1036	conditions. You can set this environment variable to make AnyEvent more
1037	talkative.
1038
1039	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1040	conditions, such as not being able to load the event model specified by
1041	C<PERL_ANYEVENT_MODEL>.
1042
1043	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1044	model it chooses.
1045
1046	=item C<PERL_ANYEVENT_MODEL>
1047
1048	This can be used to specify the event model to be used by AnyEvent, before
1049	auto detection and -probing kicks in. It must be a string consisting
1050	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1051	and the resulting module name is loaded and if the load was successful,
1052	used as event model. If it fails to load AnyEvent will proceed with
1053	auto detection and -probing.
1054
1055	This functionality might change in future versions.
1056
1057	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1058	could start your program like this:
1059
1060	PERL_ANYEVENT_MODEL=Perl perl ...
1061
1062	=item C<PERL_ANYEVENT_PROTOCOLS>
1063
1064	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1065	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1066	of auto probing).
1067
1068	Must be set to a comma-separated list of protocols or address families,
1069	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1070	used, and preference will be given to protocols mentioned earlier in the
1071	list.
1072
1073	This variable can effectively be used for denial-of-service attacks
1074	against local programs (e.g. when setuid), although the impact is likely
1075	small, as the program has to handle connection errors already-
1076
1077	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1078	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1079	- only support IPv4, never try to resolve or contact IPv6
1080	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1081	IPv6, but prefer IPv6 over IPv4.
1082
1083	=item C<PERL_ANYEVENT_EDNS0>
1084
1085	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1086	for DNS. This extension is generally useful to reduce DNS traffic, but
1087	some (broken) firewalls drop such DNS packets, which is why it is off by
1088	default.
1089
1090	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1091	EDNS0 in its DNS requests.
1092
1093	=back
1094		2099
1095	=head1 EXAMPLE PROGRAM	2100	=head1 EXAMPLE PROGRAM
1096		2101
1097	The following program uses an I/O watcher to read data from STDIN, a timer	2102	The following program uses an I/O watcher to read data from STDIN, a timer
1098	to display a message once per second, and a condition variable to quit the	2103	to display a message once per second, and a condition variable to quit the
…		…
1111	warn "read: $input\n"; # output what has been read	2116	warn "read: $input\n"; # output what has been read
1112	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2117	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1113	},	2118	},
1114	);	2119	);
1115		2120
1116	my $time_watcher; # can only be used once
1117
1118	sub new_timer {
1119	$timer = AnyEvent->timer (after => 1, cb => sub {	2121	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1120	warn "timeout\n"; # print 'timeout' about every second	2122	warn "timeout\n"; # print 'timeout' at most every second
1121	&new_timer; # and restart the time
1122	});	2123	});
1123	}
1124
1125	new_timer; # create first timer
1126		2124
1127	$cv->recv; # wait until user enters /^q/i	2125	$cv->recv; # wait until user enters /^q/i
1128		2126
1129	=head1 REAL-WORLD EXAMPLE	2127	=head1 REAL-WORLD EXAMPLE
1130		2128
…		…
1203		2201
1204	The actual code goes further and collects all errors (C<die>s, exceptions)	2202	The actual code goes further and collects all errors (C<die>s, exceptions)
1205	that occurred during request processing. The C<result> method detects	2203	that occurred during request processing. The C<result> method detects
1206	whether an exception as thrown (it is stored inside the $txn object)	2204	whether an exception as thrown (it is stored inside the $txn object)
1207	and just throws the exception, which means connection errors and other	2205	and just throws the exception, which means connection errors and other
1208	problems get reported tot he code that tries to use the result, not in a	2206	problems get reported to the code that tries to use the result, not in a
1209	random callback.	2207	random callback.
1210		2208
1211	All of this enables the following usage styles:	2209	All of this enables the following usage styles:
1212		2210
1213	1. Blocking:	2211	1. Blocking:
…		…
1261	through AnyEvent. The benchmark creates a lot of timers (with a zero	2259	through AnyEvent. The benchmark creates a lot of timers (with a zero
1262	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2260	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1263	which it is), lets them fire exactly once and destroys them again.	2261	which it is), lets them fire exactly once and destroys them again.
1264		2262
1265	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2263	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1266	distribution.	2264	distribution. It uses the L<AE> interface, which makes a real difference
		2265	for the EV and Perl backends only.
1267		2266
1268	=head3 Explanation of the columns	2267	=head3 Explanation of the columns
1269		2268
1270	I<watcher> is the number of event watchers created/destroyed. Since	2269	I<watcher> is the number of event watchers created/destroyed. Since
1271	different event models feature vastly different performances, each event	2270	different event models feature vastly different performances, each event
…		…
1292	watcher.	2291	watcher.
1293		2292
1294	=head3 Results	2293	=head3 Results
1295		2294
1296	name watchers bytes create invoke destroy comment	2295	name watchers bytes create invoke destroy comment
1297	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2296	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1298	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2297	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1299	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2298	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1300	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2299	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1301	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2300	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1302	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2301	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2302	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2303	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1303	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2304	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1304	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2305	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1305	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2306	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1306	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2307	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1307		2308
1308	=head3 Discussion	2309	=head3 Discussion
1309		2310
1310	The benchmark does I<not> measure scalability of the event loop very	2311	The benchmark does I<not> measure scalability of the event loop very
1311	well. For example, a select-based event loop (such as the pure perl one)	2312	well. For example, a select-based event loop (such as the pure perl one)
…		…
1323	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2324	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1324	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2325	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1325	cycles with POE.	2326	cycles with POE.
1326		2327
1327	C<EV> is the sole leader regarding speed and memory use, which are both	2328	C<EV> is the sole leader regarding speed and memory use, which are both
1328	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2329	maximal/minimal, respectively. When using the L<AE> API there is zero
		2330	overhead (when going through the AnyEvent API create is about 5-6 times
		2331	slower, with other times being equal, so still uses far less memory than
1329	far less memory than any other event loop and is still faster than Event	2332	any other event loop and is still faster than Event natively).
1330	natively.
1331		2333
1332	The pure perl implementation is hit in a few sweet spots (both the	2334	The pure perl implementation is hit in a few sweet spots (both the
1333	constant timeout and the use of a single fd hit optimisations in the perl	2335	constant timeout and the use of a single fd hit optimisations in the perl
1334	interpreter and the backend itself). Nevertheless this shows that it	2336	interpreter and the backend itself). Nevertheless this shows that it
1335	adds very little overhead in itself. Like any select-based backend its	2337	adds very little overhead in itself. Like any select-based backend its
1336	performance becomes really bad with lots of file descriptors (and few of	2338	performance becomes really bad with lots of file descriptors (and few of
1337	them active), of course, but this was not subject of this benchmark.	2339	them active), of course, but this was not subject of this benchmark.
1338		2340
1339	The C<Event> module has a relatively high setup and callback invocation	2341	The C<Event> module has a relatively high setup and callback invocation
1340	cost, but overall scores in on the third place.	2342	cost, but overall scores in on the third place.
		2343
		2344	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2345	when using its pure perl backend.
1341		2346
1342	C<Glib>'s memory usage is quite a bit higher, but it features a	2347	C<Glib>'s memory usage is quite a bit higher, but it features a
1343	faster callback invocation and overall ends up in the same class as	2348	faster callback invocation and overall ends up in the same class as
1344	C<Event>. However, Glib scales extremely badly, doubling the number of	2349	C<Event>. However, Glib scales extremely badly, doubling the number of
1345	watchers increases the processing time by more than a factor of four,	2350	watchers increases the processing time by more than a factor of four,
…		…
1406	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2411	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1407	(1%) are active. This mirrors the activity of large servers with many	2412	(1%) are active. This mirrors the activity of large servers with many
1408	connections, most of which are idle at any one point in time.	2413	connections, most of which are idle at any one point in time.
1409		2414
1410	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2415	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1411	distribution.	2416	distribution. It uses the L<AE> interface, which makes a real difference
		2417	for the EV and Perl backends only.
1412		2418
1413	=head3 Explanation of the columns	2419	=head3 Explanation of the columns
1414		2420
1415	I<sockets> is the number of sockets, and twice the number of "servers" (as	2421	I<sockets> is the number of sockets, and twice the number of "servers" (as
1416	each server has a read and write socket end).	2422	each server has a read and write socket end).
…		…
1423	it to another server. This includes deleting the old timeout and creating	2429	it to another server. This includes deleting the old timeout and creating
1424	a new one that moves the timeout into the future.	2430	a new one that moves the timeout into the future.
1425		2431
1426	=head3 Results	2432	=head3 Results
1427		2433
1428	name sockets create request	2434	name sockets create request
1429	EV 20000 69.01 11.16	2435	EV 20000 62.66 7.99
1430	Perl 20000 73.32 35.87	2436	Perl 20000 68.32 32.64
1431	Event 20000 212.62 257.32	2437	IOAsync 20000 174.06 101.15 epoll
1432	Glib 20000 651.16 1896.30	2438	IOAsync 20000 174.67 610.84 poll
		2439	Event 20000 202.69 242.91
		2440	Glib 20000 557.01 1689.52
1433	POE 20000 349.67 12317.24 uses POE::Loop::Event	2441	POE 20000 341.54 12086.32 uses POE::Loop::Event
1434		2442
1435	=head3 Discussion	2443	=head3 Discussion
1436		2444
1437	This benchmark I<does> measure scalability and overall performance of the	2445	This benchmark I<does> measure scalability and overall performance of the
1438	particular event loop.	2446	particular event loop.
…		…
1440	EV is again fastest. Since it is using epoll on my system, the setup time	2448	EV is again fastest. Since it is using epoll on my system, the setup time
1441	is relatively high, though.	2449	is relatively high, though.
1442		2450
1443	Perl surprisingly comes second. It is much faster than the C-based event	2451	Perl surprisingly comes second. It is much faster than the C-based event
1444	loops Event and Glib.	2452	loops Event and Glib.
		2453
		2454	IO::Async performs very well when using its epoll backend, and still quite
		2455	good compared to Glib when using its pure perl backend.
1445		2456
1446	Event suffers from high setup time as well (look at its code and you will	2457	Event suffers from high setup time as well (look at its code and you will
1447	understand why). Callback invocation also has a high overhead compared to	2458	understand why). Callback invocation also has a high overhead compared to
1448	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2459	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1449	uses select or poll in basically all documented configurations.	2460	uses select or poll in basically all documented configurations.
…		…
1512	=item * C-based event loops perform very well with small number of	2523	=item * C-based event loops perform very well with small number of
1513	watchers, as the management overhead dominates.	2524	watchers, as the management overhead dominates.
1514		2525
1515	=back	2526	=back
1516		2527
		2528	=head2 THE IO::Lambda BENCHMARK
		2529
		2530	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2531	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2532	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2533	shouldn't come as a surprise to anybody). As such, the benchmark is
		2534	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2535	very optimal. But how would AnyEvent compare when used without the extra
		2536	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2537
		2538	The benchmark itself creates an echo-server, and then, for 500 times,
		2539	connects to the echo server, sends a line, waits for the reply, and then
		2540	creates the next connection. This is a rather bad benchmark, as it doesn't
		2541	test the efficiency of the framework or much non-blocking I/O, but it is a
		2542	benchmark nevertheless.
		2543
		2544	name runtime
		2545	Lambda/select 0.330 sec
		2546	+ optimized 0.122 sec
		2547	Lambda/AnyEvent 0.327 sec
		2548	+ optimized 0.138 sec
		2549	Raw sockets/select 0.077 sec
		2550	POE/select, components 0.662 sec
		2551	POE/select, raw sockets 0.226 sec
		2552	POE/select, optimized 0.404 sec
		2553
		2554	AnyEvent/select/nb 0.085 sec
		2555	AnyEvent/EV/nb 0.068 sec
		2556	+state machine 0.134 sec
		2557
		2558	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2559	benchmarks actually make blocking connects and use 100% blocking I/O,
		2560	defeating the purpose of an event-based solution. All of the newly
		2561	written AnyEvent benchmarks use 100% non-blocking connects (using
		2562	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2563	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2564	generally require a lot more bookkeeping and event handling than blocking
		2565	connects (which involve a single syscall only).
		2566
		2567	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2568	offers similar expressive power as POE and IO::Lambda, using conventional
		2569	Perl syntax. This means that both the echo server and the client are 100%
		2570	non-blocking, further placing it at a disadvantage.
		2571
		2572	As you can see, the AnyEvent + EV combination even beats the
		2573	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2574	backend easily beats IO::Lambda and POE.
		2575
		2576	And even the 100% non-blocking version written using the high-level (and
		2577	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2578	higher level ("unoptimised") abstractions by a large margin, even though
		2579	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2580
		2581	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2582	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2583	part of the IO::Lambda distribution and were used without any changes.
		2584
		2585
		2586	=head1 SIGNALS
		2587
		2588	AnyEvent currently installs handlers for these signals:
		2589
		2590	=over 4
		2591
		2592	=item SIGCHLD
		2593
		2594	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2595	emulation for event loops that do not support them natively. Also, some
		2596	event loops install a similar handler.
		2597
		2598	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2599	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2600
		2601	=item SIGPIPE
		2602
		2603	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2604	when AnyEvent gets loaded.
		2605
		2606	The rationale for this is that AnyEvent users usually do not really depend
		2607	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2608	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2609	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2610	some random socket.
		2611
		2612	The rationale for installing a no-op handler as opposed to ignoring it is
		2613	that this way, the handler will be restored to defaults on exec.
		2614
		2615	Feel free to install your own handler, or reset it to defaults.
		2616
		2617	=back
		2618
		2619	=cut
		2620
		2621	undef $SIG{CHLD}
		2622	if $SIG{CHLD} eq 'IGNORE';
		2623
		2624	$SIG{PIPE} = sub { }
		2625	unless defined $SIG{PIPE};
		2626
		2627	=head1 RECOMMENDED/OPTIONAL MODULES
		2628
		2629	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2630	its built-in modules) are required to use it.
		2631
		2632	That does not mean that AnyEvent won't take advantage of some additional
		2633	modules if they are installed.
		2634
		2635	This section explains which additional modules will be used, and how they
		2636	affect AnyEvent's operation.
		2637
		2638	=over 4
		2639
		2640	=item L<Async::Interrupt>
		2641
		2642	This slightly arcane module is used to implement fast signal handling: To
		2643	my knowledge, there is no way to do completely race-free and quick
		2644	signal handling in pure perl. To ensure that signals still get
		2645	delivered, AnyEvent will start an interval timer to wake up perl (and
		2646	catch the signals) with some delay (default is 10 seconds, look for
		2647	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2648
		2649	If this module is available, then it will be used to implement signal
		2650	catching, which means that signals will not be delayed, and the event loop
		2651	will not be interrupted regularly, which is more efficient (and good for
		2652	battery life on laptops).
		2653
		2654	This affects not just the pure-perl event loop, but also other event loops
		2655	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2656
		2657	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2658	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2659	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2660	does nothing for those backends.
		2661
		2662	=item L<EV>
		2663
		2664	This module isn't really "optional", as it is simply one of the backend
		2665	event loops that AnyEvent can use. However, it is simply the best event
		2666	loop available in terms of features, speed and stability: It supports
		2667	the AnyEvent API optimally, implements all the watcher types in XS, does
		2668	automatic timer adjustments even when no monotonic clock is available,
		2669	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2670	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2671	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2672
		2673	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2674	then this module will do nothing for you.
		2675
		2676	=item L<Guard>
		2677
		2678	The guard module, when used, will be used to implement
		2679	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2680	lot less memory), but otherwise doesn't affect guard operation much. It is
		2681	purely used for performance.
		2682
		2683	=item L<JSON> and L<JSON::XS>
		2684
		2685	One of these modules is required when you want to read or write JSON data
		2686	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2687	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2688
		2689	=item L<Net::SSLeay>
		2690
		2691	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2692	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2693	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2694
		2695	=item L<Time::HiRes>
		2696
		2697	This module is part of perl since release 5.008. It will be used when the
		2698	chosen event library does not come with a timing source of its own. The
		2699	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2700	try to use a monotonic clock for timing stability.
		2701
		2702	=back
		2703
1517		2704
1518	=head1 FORK	2705	=head1 FORK
1519		2706
1520	Most event libraries are not fork-safe. The ones who are usually are	2707	Most event libraries are not fork-safe. The ones who are usually are
1521	because they rely on inefficient but fork-safe C<select> or C<poll>	2708	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1522	calls. Only L<EV> is fully fork-aware.	2709	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2710	are usually badly thought-out hacks that are incompatible with fork in
		2711	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2712	continue event-processing in both parent and child (or both, if you know
		2713	what you are doing).
		2714
		2715	This means that, in general, you cannot fork and do event processing in
		2716	the child if the event library was initialised before the fork (which
		2717	usually happens when the first AnyEvent watcher is created, or the library
		2718	is loaded).
1523		2719
1524	If you have to fork, you must either do so I<before> creating your first	2720	If you have to fork, you must either do so I<before> creating your first
1525	watcher OR you must not use AnyEvent at all in the child.	2721	watcher OR you must not use AnyEvent at all in the child OR you must do
		2722	something completely out of the scope of AnyEvent.
		2723
		2724	The problem of doing event processing in the parent I<and> the child
		2725	is much more complicated: even for backends that I<are> fork-aware or
		2726	fork-safe, their behaviour is not usually what you want: fork clones all
		2727	watchers, that means all timers, I/O watchers etc. are active in both
		2728	parent and child, which is almost never what you want. USing C<exec>
		2729	to start worker children from some kind of manage rprocess is usually
		2730	preferred, because it is much easier and cleaner, at the expense of having
		2731	to have another binary.
1526		2732
1527		2733
1528	=head1 SECURITY CONSIDERATIONS	2734	=head1 SECURITY CONSIDERATIONS
1529		2735
1530	AnyEvent can be forced to load any event model via	2736	AnyEvent can be forced to load any event model via
…		…
1535	specified in the variable.	2741	specified in the variable.
1536		2742
1537	You can make AnyEvent completely ignore this variable by deleting it	2743	You can make AnyEvent completely ignore this variable by deleting it
1538	before the first watcher gets created, e.g. with a C<BEGIN> block:	2744	before the first watcher gets created, e.g. with a C<BEGIN> block:
1539		2745
1540	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2746	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1541		2747
1542	use AnyEvent;	2748	use AnyEvent;
1543		2749
1544	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2750	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1545	be used to probe what backend is used and gain other information (which is	2751	be used to probe what backend is used and gain other information (which is
1546	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2752	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2753	$ENV{PERL_ANYEVENT_STRICT}.
		2754
		2755	Note that AnyEvent will remove I<all> environment variables starting with
		2756	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2757	enabled.
		2758
		2759
		2760	=head1 BUGS
		2761
		2762	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2763	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2764	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2765	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2766	pronounced).
1547		2767
1548		2768
1549	=head1 SEE ALSO	2769	=head1 SEE ALSO
1550		2770
		2771	Tutorial/Introduction: L<AnyEvent::Intro>.
		2772
		2773	FAQ: L<AnyEvent::FAQ>.
		2774
1551	Utility functions: L<AnyEvent::Util>.	2775	Utility functions: L<AnyEvent::Util>.
1552		2776
1553	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2777	Event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>, L<Glib::EV>,
1554	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2778	L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1555		2779
1556	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2780	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1557	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2781	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1558	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2782	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1559	L<AnyEvent::Impl::POE>.	2783	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1560		2784
1561	Non-blocking file handles, sockets, TCP clients and	2785	Non-blocking file handles, sockets, TCP clients and
1562	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2786	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1563		2787
1564	Asynchronous DNS: L<AnyEvent::DNS>.	2788	Asynchronous DNS: L<AnyEvent::DNS>.
1565		2789
1566	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2790	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1567		2791
1568	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2792	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2793	L<AnyEvent::HTTP>.
1569		2794
1570		2795
1571	=head1 AUTHOR	2796	=head1 AUTHOR
1572		2797
1573	Marc Lehmann <schmorp@schmorp.de>	2798	Marc Lehmann <schmorp@schmorp.de>
1574	http://home.schmorp.de/	2799	http://home.schmorp.de/
1575		2800
1576	=cut	2801	=cut
1577		2802
1578	1	2803	1
1579		2804

Diff Legend

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