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Revision 1.365 by root, Tue Aug 16 14:47:26 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 { ... });
12		17
		18	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
15		21
16	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		24
		25	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	26	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		27
		28	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	29	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	30	my ($pid, $status) = @_;
23	...	31	...
24	});	32	});
		33
		34	# called when event loop idle (if applicable)
		35	my $w = AnyEvent->idle (cb => sub { ... });
25		36
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	37	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	38	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	39	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	40	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	43	=head1 INTRODUCTION/TUTORIAL
33		44
34	This manpage is mainly a reference manual. If you are interested	45	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	46	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	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.
37		58
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	59	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		60
40	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
41	nowadays. So what is different about AnyEvent?	62	nowadays. So what is different about AnyEvent?
…		…
57	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
58	model you use.	79	model you use.
59		80
60	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
61	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
62	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
63	cannot use anything else, as they are simply incompatible to everything	84	cannot use anything else, as they are simply incompatible to everything
64	that isn't them. What's worse, all the potential users of your	85	that isn't them. What's worse, all the potential users of your
65	module are 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.
66		87
67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	88	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
68	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
69	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
70	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
71	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
72	event models it supports (including stuff like IO::Async, as long as those	93	supports (including stuff like IO::Async, as long as those use one of the
73	use one of the supported event loops. It is trivial to add new event loops	94	supported event loops. It is easy to add new event loops to AnyEvent, too,
74	to AnyEvent, too, so it is future-proof).	95	so it is future-proof).
75		96
76	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
77	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
78	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
79	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
80	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
81	technically possible.	102	technically possible.
82		103
83	Of course, AnyEvent comes with a big (and fully optional!) toolbox	104	Of course, AnyEvent comes with a big (and fully optional!) toolbox
84	of useful functionality, such as an asynchronous DNS resolver, 100%	105	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
90	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
91	model, you should I<not> use this module.	112	model, you should I<not> use this module.
92		113
93	=head1 DESCRIPTION	114	=head1 DESCRIPTION
94		115
95	L<AnyEvent> provides an identical interface to multiple event loops. This	116	L<AnyEvent> provides a uniform interface to various event loops. This
96	allows module authors to utilise an event loop without forcing module	117	allows module authors to use event loop functionality without forcing
97	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
98	peacefully at any one time).	119	than one event loop cannot coexist peacefully).
99		120
100	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>
101	module.	122	module.
102		123
103	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
104	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
105	following modules is already loaded: L<EV>,	126	following modules is already loaded: L<EV>, L<AnyEvent::Loop>,
106	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
107	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
108	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
109	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
110	be successfully loaded will be used. If, after this, still none could be	131	the other two are not normally tried.
111	found, AnyEvent will fall back to a pure-perl event loop, which is not
112	very efficient, but should work everywhere.
113		132
114	Because AnyEvent first checks for modules that are already loaded, loading	133	Because AnyEvent first checks for modules that are already loaded, loading
115	an event model explicitly before first using AnyEvent will likely make	134	an event model explicitly before first using AnyEvent will likely make
116	that model the default. For example:	135	that model the default. For example:
117		136
…		…
119	use AnyEvent;	138	use AnyEvent;
120		139
121	# .. AnyEvent will likely default to Tk	140	# .. AnyEvent will likely default to Tk
122		141
123	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
124	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,
125	use AnyEvent so their modules work together with others seamlessly...	144	as very few modules hardcode event loops without announcing this very
		145	loudly.
126		146
127	The pure-perl implementation of AnyEvent is called	147	The pure-perl implementation of AnyEvent is called C<AnyEvent::Loop>. Like
128	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
129	explicitly and enjoy the high availability of that event loop :)	149	availability of that event loop :)
130		150
131	=head1 WATCHERS	151	=head1 WATCHERS
132		152
133	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
134	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
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	157	These watchers are normal Perl objects with normal Perl lifetime. After
138	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
139	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
140	is in control).	160	is in control).
141		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
142	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
143	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
144	to it).	170	to it).
145		171
146	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.
147		173
148	Many watchers either are used with "recursion" (repeating timers for	174	Many watchers either are used with "recursion" (repeating timers for
149	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.
150		176
151	An any way to achieve that is this pattern:	177	One way to achieve that is this pattern:
152		178
153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	179	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
154	# you can use $w here, for example to undef it	180	# you can use $w here, for example to undef it
155	undef $w;	181	undef $w;
156	});	182	});
…		…
159	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
160	declared.	186	declared.
161		187
162	=head2 I/O WATCHERS	188	=head2 I/O WATCHERS
163		189
		190	$w = AnyEvent->io (
		191	fh => <filehandle_or_fileno>,
		192	poll => <"r" or "w">,
		193	cb => <callback>,
		194	);
		195
164	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
165	with the following mandatory key-value pairs as arguments:	197	with the following mandatory key-value pairs as arguments:
166		198
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	199	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
168	(AnyEvent might or might not keep a reference to this file handle). C<poll>	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
169	must be a string that is either C<r> or C<w>, which creates a watcher	206	C<poll> must be a string that is either C<r> or C<w>, which creates a
170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	207	watcher waiting for "r"eadable or "w"ritable events, respectively.
		208
171	callback to invoke each time the file handle becomes ready.	209	C<cb> is the callback to invoke each time the file handle becomes ready.
172		210
173	Although the callback might get passed parameters, their value and	211	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	212	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	213	callbacks cannot use arguments passed to I/O watcher callbacks.
176		214
177	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.
178	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
179	underlying file descriptor.	217	underlying file descriptor.
180		218
181	Some event loops issue spurious readyness notifications, so you should	219	Some event loops issue spurious readiness notifications, so you should
182	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
183	handles.	221	handles.
184		222
185	Example: wait for readability of STDIN, then read a line and disable the	223	Example: wait for readability of STDIN, then read a line and disable the
186	watcher.	224	watcher.
…		…
191	undef $w;	229	undef $w;
192	});	230	});
193		231
194	=head2 TIME WATCHERS	232	=head2 TIME WATCHERS
195		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
196	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 >>
197	method with the following mandatory arguments:	243	method with the following mandatory arguments:
198		244
199	C<after> specifies after how many seconds (fractional values are	245	C<after> specifies after how many seconds (fractional values are
200	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
…		…
202		248
203	Although the callback might get passed parameters, their value and	249	Although the callback might get passed parameters, their value and
204	presence is undefined and you cannot rely on them. Portable AnyEvent	250	presence is undefined and you cannot rely on them. Portable AnyEvent
205	callbacks cannot use arguments passed to time watcher callbacks.	251	callbacks cannot use arguments passed to time watcher callbacks.
206		252
207	The callback will normally be invoked once only. If you specify another	253	The callback will normally be invoked only once. If you specify another
208	parameter, C<interval>, as a strictly positive number (> 0), then the	254	parameter, C<interval>, as a strictly positive number (> 0), then the
209	callback will be invoked regularly at that interval (in fractional	255	callback will be invoked regularly at that interval (in fractional
210	seconds) after the first invocation. If C<interval> is specified with a	256	seconds) after the first invocation. If C<interval> is specified with a
211	false value, then it is treated as if it were missing.	257	false value, then it is treated as if it were not specified at all.
212		258
213	The callback will be rescheduled before invoking the callback, but no	259	The callback will be rescheduled before invoking the callback, but no
214	attempt is done to avoid timer drift in most backends, so the interval is	260	attempt is made to avoid timer drift in most backends, so the interval is
215	only approximate.	261	only approximate.
216		262
217	Example: fire an event after 7.7 seconds.	263	Example: fire an event after 7.7 seconds.
218		264
219	my $w = AnyEvent->timer (after => 7.7, cb => sub {	265	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
237		283
238	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
239	use absolute time internally. This makes a difference when your clock	285	use absolute time internally. This makes a difference when your clock
240	"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
241	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
242	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.
243		289
244	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
245	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
246	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)
247	timers.	293	timers.
248		294
249	AnyEvent always prefers relative timers, if available, matching the	295	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	296	AnyEvent API.
…		…
272	I<In almost all cases (in all cases if you don't care), this is the	318	I<In almost all cases (in all cases if you don't care), this is the
273	function to call when you want to know the current time.>	319	function to call when you want to know the current time.>
274		320
275	This function is also often faster then C<< AnyEvent->time >>, and	321	This function is also often faster then C<< AnyEvent->time >>, and
276	thus the preferred method if you want some timestamp (for example,	322	thus the preferred method if you want some timestamp (for example,
277	L<AnyEvent::Handle> uses this to update it's activity timeouts).	323	L<AnyEvent::Handle> uses this to update its activity timeouts).
278		324
279	The rest of this section is only of relevance if you try to be very exact	325	The rest of this section is only of relevance if you try to be very exact
280	with your timing, you can skip it without bad conscience.	326	with your timing; you can skip it without a bad conscience.
281		327
282	For a practical example of when these times differ, consider L<Event::Lib>	328	For a practical example of when these times differ, consider L<Event::Lib>
283	and L<EV> and the following set-up:	329	and L<EV> and the following set-up:
284		330
285	The event loop is running and has just invoked one of your callback at	331	The event loop is running and has just invoked one of your callbacks at
286	time=500 (assume no other callbacks delay processing). In your callback,	332	time=500 (assume no other callbacks delay processing). In your callback,
287	you wait a second by executing C<sleep 1> (blocking the process for a	333	you wait a second by executing C<sleep 1> (blocking the process for a
288	second) and then (at time=501) you create a relative timer that fires	334	second) and then (at time=501) you create a relative timer that fires
289	after three seconds.	335	after three seconds.
290		336
…		…
308	In either case, if you care (and in most cases, you don't), then you	354	In either case, if you care (and in most cases, you don't), then you
309	can get whatever behaviour you want with any event loop, by taking the	355	can get whatever behaviour you want with any event loop, by taking the
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	356	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	357	account.
312		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
313	=back	381	=back
314		382
315	=head2 SIGNAL WATCHERS	383	=head2 SIGNAL WATCHERS
		384
		385	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
316		386
317	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
318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	388	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
319	callback to be invoked whenever a signal occurs.	389	callback to be invoked whenever a signal occurs.
320		390
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	396	invocation, and callback invocation will be synchronous. Synchronous means
327	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,
328	but it is guaranteed not to interrupt any other callbacks.	398	but it is guaranteed not to interrupt any other callbacks.
329		399
330	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
331	between multiple watchers.	401	between multiple watchers, and AnyEvent will ensure that signals will not
		402	interrupt your program at bad times.
332		403
333	This watcher might use C<%SIG>, so programs overwriting those signals	404	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	405	so programs overwriting those signals directly will likely not work
		406	correctly.
335		407
336	Example: exit on SIGINT	408	Example: exit on SIGINT
337		409
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	410	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		411
		412	=head3 Restart Behaviour
		413
		414	While restart behaviour is up to the event loop implementation, most will
		415	not restart syscalls (that includes L<Async::Interrupt> and AnyEvent's
		416	pure perl implementation).
		417
		418	=head3 Safe/Unsafe Signals
		419
		420	Perl signals can be either "safe" (synchronous to opcode handling) or
		421	"unsafe" (asynchronous) - the former might get delayed indefinitely, the
		422	latter might corrupt your memory.
		423
		424	AnyEvent signal handlers are, in addition, synchronous to the event loop,
		425	i.e. they will not interrupt your running perl program but will only be
		426	called as part of the normal event handling (just like timer, I/O etc.
		427	callbacks, too).
		428
		429	=head3 Signal Races, Delays and Workarounds
		430
		431	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		432	callbacks to signals in a generic way, which is a pity, as you cannot
		433	do race-free signal handling in perl, requiring C libraries for
		434	this. AnyEvent will try to do its best, which means in some cases,
		435	signals will be delayed. The maximum time a signal might be delayed is
		436	specified in C<$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
340	=head2 CHILD PROCESS WATCHERS	449	=head2 CHILD PROCESS WATCHERS
341		450
		451	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		452
342	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.
343		454
344	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,
345	watches for any child process exit). The watcher will triggered only when	456	using C<0> watches for any child process exit, on others this will
346	the child process has finished and an exit status is available, not on	457	croak). The watcher will be triggered only when the child process has
347	any trace events (stopped/continued).	458	finished and an exit status is available, not on any trace events
		459	(stopped/continued).
348		460
349	The callback will be called with the pid and exit status (as returned by	461	The callback will be called with the pid and exit status (as returned by
350	waitpid), so unlike other watcher types, you I<can> rely on child watcher	462	waitpid), so unlike other watcher types, you I<can> rely on child watcher
351	callback arguments.	463	callback arguments.
352		464
…		…
357		469
358	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
359	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
360	have exited already (and no SIGCHLD will be sent anymore).	472	have exited already (and no SIGCHLD will be sent anymore).
361		473
362	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
363	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
364	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.
365		480
366	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
367	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
368	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.
369		489
370	Example: fork a process and wait for it	490	Example: fork a process and wait for it
371		491
372	my $done = AnyEvent->condvar;	492	my $done = AnyEvent->condvar;
373		493
…		…
383	);	503	);
384		504
385	# do something else, then wait for process exit	505	# do something else, then wait for process exit
386	$done->recv;	506	$done->recv;
387		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	});
		547
388	=head2 CONDITION VARIABLES	548	=head2 CONDITION VARIABLES
		549
		550	$cv = AnyEvent->condvar;
		551
		552	$cv->send (<list>);
		553	my @res = $cv->recv;
389		554
390	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
391	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
392	will actively watch for new events and call your callbacks.	557	will actively watch for new events and call your callbacks.
393		558
394	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
395	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).
396		561
397	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
398	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.
399		566
400	Condition variables can be created by calling the C<< AnyEvent->condvar	567	Condition variables can be created by calling the C<< AnyEvent->condvar
401	>> method, usually without arguments. The only argument pair allowed is	568	>> method, usually without arguments. The only argument pair allowed is
402
403	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
404	becomes true, with the condition variable as the first argument (but not	570	becomes true, with the condition variable as the first argument (but not
405	the results).	571	the results).
406		572
407	After creation, the condition variable is "false" until it becomes "true"	573	After creation, the condition variable is "false" until it becomes "true"
408	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
409	were a callback, read about the caveats in the description for the C<<	575	were a callback, read about the caveats in the description for the C<<
410	->send >> method).	576	->send >> method).
411		577
412	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
413	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:
414	in time where multiple outstanding events have been processed. And yet	580
415	another way to call them is transactions - each condition variable can be	581	=over 4
416	used to represent a transaction, which finishes at some point and delivers	582
417	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
418		601
419	Condition variables are very useful to signal that something has finished,	602	Condition variables are very useful to signal that something has finished,
420	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,
421	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
422	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
…		…
435		618
436	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
437	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
438	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
439	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
440	it's C<new> method in your own C<new> method.	623	its C<new> method in your own C<new> method.
441		624
442	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
443	eventually calls C<< -> send >>, and the "consumer side", which waits	626	eventually calls C<< -> send >>, and the "consumer side", which waits
444	for the send to occur.	627	for the send to occur.
445		628
446	Example: wait for a timer.	629	Example: wait for a timer.
447		630
448	# wait till the result is ready	631	# condition: "wait till the timer is fired"
449	my $result_ready = AnyEvent->condvar;	632	my $timer_fired = AnyEvent->condvar;
450		633
451	# do something such as adding a timer	634	# create the timer - we could wait for, say
452	# or socket watcher the calls $result_ready->send	635	# a handle becomign ready, or even an
453	# when the "result" is ready.	636	# AnyEvent::HTTP request to finish, but
454	# in this case, we simply use a timer:	637	# in this case, we simply use a timer:
455	my $w = AnyEvent->timer (	638	my $w = AnyEvent->timer (
456	after => 1,	639	after => 1,
457	cb => sub { $result_ready->send },	640	cb => sub { $timer_fired->send },
458	);	641	);
459		642
460	# this "blocks" (while handling events) till the callback	643	# this "blocks" (while handling events) till the callback
461	# calls send	644	# calls ->send
462	$result_ready->recv;	645	$timer_fired->recv;
463		646
464	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
465	condition variables are also code references.	648	variables are also callable directly.
466		649
467	my $done = AnyEvent->condvar;	650	my $done = AnyEvent->condvar;
468	my $delay = AnyEvent->timer (after => 5, cb => $done);	651	my $delay = AnyEvent->timer (after => 5, cb => $done);
469	$done->recv;	652	$done->recv;
470		653
…		…
476		659
477	...	660	...
478		661
479	my @info = $couchdb->info->recv;	662	my @info = $couchdb->info->recv;
480		663
481	And this is how you would just ste a callback to be called whenever the	664	And this is how you would just set a callback to be called whenever the
482	results are available:	665	results are available:
483		666
484	$couchdb->info->cb (sub {	667	$couchdb->info->cb (sub {
485	my @info = $_[0]->recv;	668	my @info = $_[0]->recv;
486	});	669	});
…		…
504	immediately from within send.	687	immediately from within send.
505		688
506	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
507	future C<< ->recv >> calls.	690	future C<< ->recv >> calls.
508		691
509	Condition variables are overloaded so one can call them directly	692	Condition variables are overloaded so one can call them directly (as if
510	(as a code reference). Calling them directly is the same as calling	693	they were a code reference). Calling them directly is the same as calling
511	C<send>. Note, however, that many C-based event loops do not handle	694	C<send>.
512	overloading, so as tempting as it may be, passing a condition variable
513	instead of a callback does not work. Both the pure perl and EV loops
514	support overloading, however, as well as all functions that use perl to
515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
516	example).
517		695
518	=item $cv->croak ($error)	696	=item $cv->croak ($error)
519		697
520	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
521	C<Carp::croak> with the given error message/object/scalar.	699	C<Carp::croak> with the given error message/object/scalar.
522		700
523	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
524	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.
525		707
526	=item $cv->begin ([group callback])	708	=item $cv->begin ([group callback])
527		709
528	=item $cv->end	710	=item $cv->end
529
530	These two methods are EXPERIMENTAL and MIGHT CHANGE.
531		711
532	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
533	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
534	to use a condition variable for the whole process.	714	to use a condition variable for the whole process.
535		715
536	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
537	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
538	>>, 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
539	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
540	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.
541		722
542	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:
543		730
544	my $cv = AnyEvent->condvar;	731	my $cv = AnyEvent->condvar;
545		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
546	my %result;	757	my %result;
547	$cv->begin (sub { $cv->send (\%result) });	758	$cv->begin (sub { shift->send (\%result) });
548		759
549	for my $host (@list_of_hosts) {	760	for my $host (@list_of_hosts) {
550	$cv->begin;	761	$cv->begin;
551	ping_host_then_call_callback $host, sub {	762	ping_host_then_call_callback $host, sub {
552	$result{$host} = ...;	763	$result{$host} = ...;
…		…
567	loop, which serves two important purposes: first, it sets the callback	778	loop, which serves two important purposes: first, it sets the callback
568	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
569	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
570	doesn't execute once).	781	doesn't execute once).
571		782
572	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
573	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
574	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
575	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>.
576		788
577	=back	789	=back
578		790
579	=head3 METHODS FOR CONSUMERS	791	=head3 METHODS FOR CONSUMERS
580		792
…		…
584	=over 4	796	=over 4
585		797
586	=item $cv->recv	798	=item $cv->recv
587		799
588	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	800	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
589	>> methods have been called on c<$cv>, while servicing other watchers	801	>> methods have been called on C<$cv>, while servicing other watchers
590	normally.	802	normally.
591		803
592	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
593	will return immediately.	805	will return immediately.
594		806
…		…
596	function will call C<croak>.	808	function will call C<croak>.
597		809
598	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,
599	in scalar context only the first one will be returned.	811	in scalar context only the first one will be returned.
600		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
601	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
602	(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
603	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
604	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
605	condition variables with some kind of request results and supporting	824	condition variables with some kind of request results and supporting
606	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,
607	while still supporting blocking waits if the caller so desires).	826	while still supporting blocking waits if the caller so desires).
608		827
609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
610	sensibly have two C<< ->recv >>'s in parallel, as that would require
611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
612	can supply.
613
614	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
615	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
616	versions and also integrates coroutines into AnyEvent, making blocking
617	C<< ->recv >> calls perfectly safe as long as they are done from another
618	coroutine (one that doesn't run the event loop).
619
620	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
621	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
622	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
623	waits otherwise.	831	waits otherwise.
624		832
625	=item $bool = $cv->ready	833	=item $bool = $cv->ready
…		…
631		839
632	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
633	replaces it before doing so.	841	replaces it before doing so.
634		842
635	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
636	C<send> or C<croak> are called, with the only argument being the condition	844	C<send> or C<croak> are called, with the only argument being the
637	variable itself. Calling C<recv> inside the callback or at any later time	845	condition variable itself. If the condition is already true, the
638	is guaranteed not to block.	846	callback is called immediately when it is set. Calling C<recv> inside
		847	the callback or at any later time is guaranteed not to block.
639		848
640	=back	849	=back
641		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
642	=head1 GLOBAL VARIABLES AND FUNCTIONS	914	=head1 GLOBAL VARIABLES AND FUNCTIONS
643		915
		916	These are not normally required to use AnyEvent, but can be useful to
		917	write AnyEvent extension modules.
		918
644	=over 4	919	=over 4
645		920
646	=item $AnyEvent::MODEL	921	=item $AnyEvent::MODEL
647		922
648	Contains C<undef> until the first watcher is being created. Then it	923	Contains C<undef> until the first watcher is being created, before the
		924	backend has been autodetected.
		925
649	contains the event model that is being used, which is the name of the	926	Afterwards it contains the event model that is being used, which is the
650	Perl class implementing the model. This class is usually one of the	927	name of the Perl class implementing the model. This class is usually one
651	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	928	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
652	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	929	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
653		930	will be C<urxvt::anyevent>).
654	The known classes so far are:
655
656	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
657	AnyEvent::Impl::Event based on Event, second best choice.
658	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
659	AnyEvent::Impl::Glib based on Glib, third-best choice.
660	AnyEvent::Impl::Tk based on Tk, very bad choice.
661	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
662	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
663	AnyEvent::Impl::POE based on POE, not generic enough for full support.
664
665	There is no support for WxWidgets, as WxWidgets has no support for
666	watching file handles. However, you can use WxWidgets through the
667	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
668	second, which was considered to be too horrible to even consider for
669	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
670	it's adaptor.
671
672	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
673	autodetecting them.
674		931
675	=item AnyEvent::detect	932	=item AnyEvent::detect
676		933
677	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	934	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
678	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
679	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
680	runtime.	937	runtime, and not e.g. during initialisation of your module.
		938
		939	The effect of calling this function is as if a watcher had been created
		940	(specifically, actions that happen "when the first watcher is created"
		941	happen when calling detetc as well).
		942
		943	If you need to do some initialisation before AnyEvent watchers are
		944	created, use C<post_detect>.
681		945
682	=item $guard = AnyEvent::post_detect { BLOCK }	946	=item $guard = AnyEvent::post_detect { BLOCK }
683		947
684	Arranges for the code block to be executed as soon as the event model is	948	Arranges for the code block to be executed as soon as the event model is
685	autodetected (or immediately if this has already happened).	949	autodetected (or immediately if that has already happened).
		950
		951	The block will be executed I<after> the actual backend has been detected
		952	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		953	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		954	other initialisations - see the sources of L<AnyEvent::Strict> or
		955	L<AnyEvent::AIO> to see how this is used.
		956
		957	The most common usage is to create some global watchers, without forcing
		958	event module detection too early, for example, L<AnyEvent::AIO> creates
		959	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		960	avoid autodetecting the event module at load time.
686		961
687	If called in scalar or list context, then it creates and returns an object	962	If called in scalar or list context, then it creates and returns an object
688	that automatically removes the callback again when it is destroyed. See	963	that automatically removes the callback again when it is destroyed (or
		964	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
689	L<Coro::BDB> for a case where this is useful.	965	a case where this is useful.
		966
		967	Example: Create a watcher for the IO::AIO module and store it in
		968	C<$WATCHER>, but do so only do so after the event loop is initialised.
		969
		970	our WATCHER;
		971
		972	my $guard = AnyEvent::post_detect {
		973	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		974	};
		975
		976	# the ||= is important in case post_detect immediately runs the block,
		977	# as to not clobber the newly-created watcher. assigning both watcher and
		978	# post_detect guard to the same variable has the advantage of users being
		979	# able to just C<undef $WATCHER> if the watcher causes them grief.
		980
		981	$WATCHER ||= $guard;
690		982
691	=item @AnyEvent::post_detect	983	=item @AnyEvent::post_detect
692		984
693	If there are any code references in this array (you can C<push> to it	985	If there are any code references in this array (you can C<push> to it
694	before or after loading AnyEvent), then they will called directly after	986	before or after loading AnyEvent), then they will be called directly
695	the event loop has been chosen.	987	after the event loop has been chosen.
696		988
697	You should check C<$AnyEvent::MODEL> before adding to this array, though:	989	You should check C<$AnyEvent::MODEL> before adding to this array, though:
698	if it contains a true value then the event loop has already been detected,	990	if it is defined then the event loop has already been detected, and the
699	and the array will be ignored.	991	array will be ignored.
700		992
701	Best use C<AnyEvent::post_detect { BLOCK }> instead.	993	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		994	it, as it takes care of these details.
		995
		996	This variable is mainly useful for modules that can do something useful
		997	when AnyEvent is used and thus want to know when it is initialised, but do
		998	not need to even load it by default. This array provides the means to hook
		999	into AnyEvent passively, without loading it.
		1000
		1001	Example: To load Coro::AnyEvent whenever Coro and AnyEvent are used
		1002	together, you could put this into Coro (this is the actual code used by
		1003	Coro to accomplish this):
		1004
		1005	if (defined $AnyEvent::MODEL) {
		1006	# AnyEvent already initialised, so load Coro::AnyEvent
		1007	require Coro::AnyEvent;
		1008	} else {
		1009	# AnyEvent not yet initialised, so make sure to load Coro::AnyEvent
		1010	# as soon as it is
		1011	push @AnyEvent::post_detect, sub { require Coro::AnyEvent };
		1012	}
		1013
		1014	=item AnyEvent::postpone { BLOCK }
		1015
		1016	Arranges for the block to be executed as soon as possible, but not before
		1017	the call itself returns. In practise, the block will be executed just
		1018	before the event loop polls for new events, or shortly afterwards.
		1019
		1020	This function never returns anything (to make the C<return postpone { ...
		1021	}> idiom more useful.
		1022
		1023	To understand the usefulness of this function, consider a function that
		1024	asynchronously does something for you and returns some transaction
		1025	object or guard to let you cancel the operation. For example,
		1026	C<AnyEvent::Socket::tcp_connect>:
		1027
		1028	# start a conenction attempt unless one is active
		1029	$self->{connect_guard} ||= AnyEvent::Socket::tcp_connect "www.example.net", 80, sub {
		1030	delete $self->{connect_guard};
		1031	...
		1032	};
		1033
		1034	Imagine that this function could instantly call the callback, for
		1035	example, because it detects an obvious error such as a negative port
		1036	number. Invoking the callback before the function returns causes problems
		1037	however: the callback will be called and will try to delete the guard
		1038	object. But since the function hasn't returned yet, there is nothing to
		1039	delete. When the function eventually returns it will assign the guard
		1040	object to C<< $self->{connect_guard} >>, where it will likely never be
		1041	deleted, so the program thinks it is still trying to connect.
		1042
		1043	This is where C<AnyEvent::postpone> should be used. Instead of calling the
		1044	callback directly on error:
		1045
		1046	$cb->(undef), return # signal error to callback, BAD!
		1047	if $some_error_condition;
		1048
		1049	It should use C<postpone>:
		1050
		1051	AnyEvent::postpone { $cb->(undef) }, return # signal error to callback, later
		1052	if $some_error_condition;
		1053
		1054	=item AnyEvent::log $level, $msg[, @args]
		1055
		1056	Log the given C<$msg> at the given C<$level>.
		1057
		1058	Loads AnyEvent::Log on first use and calls C<AnyEvent::Log::log> -
		1059	consequently, look at the L<AnyEvent::Log> documentation for details.
702		1060
703	=back	1061	=back
704		1062
705	=head1 WHAT TO DO IN A MODULE	1063	=head1 WHAT TO DO IN A MODULE
706		1064
…		…
717	because it will stall the whole program, and the whole point of using	1075	because it will stall the whole program, and the whole point of using
718	events is to stay interactive.	1076	events is to stay interactive.
719		1077
720	It is fine, however, to call C<< ->recv >> when the user of your module	1078	It is fine, however, to call C<< ->recv >> when the user of your module
721	requests it (i.e. if you create a http request object ad have a method	1079	requests it (i.e. if you create a http request object ad have a method
722	called C<results> that returns the results, it should call C<< ->recv >>	1080	called C<results> that returns the results, it may call C<< ->recv >>
723	freely, as the user of your module knows what she is doing. always).	1081	freely, as the user of your module knows what she is doing. Always).
724		1082
725	=head1 WHAT TO DO IN THE MAIN PROGRAM	1083	=head1 WHAT TO DO IN THE MAIN PROGRAM
726		1084
727	There will always be a single main program - the only place that should	1085	There will always be a single main program - the only place that should
728	dictate which event model to use.	1086	dictate which event model to use.
729		1087
730	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1088	If the program is not event-based, it need not do anything special, even
731	do anything special (it does not need to be event-based) and let AnyEvent	1089	when it depends on a module that uses an AnyEvent. If the program itself
732	decide which implementation to chose if some module relies on it.	1090	uses AnyEvent, but does not care which event loop is used, all it needs
		1091	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1092	available loop implementation.
733		1093
734	If the main program relies on a specific event model - for example, in	1094	If the main program relies on a specific event model - for example, in
735	Gtk2 programs you have to rely on the Glib module - you should load the	1095	Gtk2 programs you have to rely on the Glib module - you should load the
736	event module before loading AnyEvent or any module that uses it: generally	1096	event module before loading AnyEvent or any module that uses it: generally
737	speaking, you should load it as early as possible. The reason is that	1097	speaking, you should load it as early as possible. The reason is that
738	modules might create watchers when they are loaded, and AnyEvent will	1098	modules might create watchers when they are loaded, and AnyEvent will
739	decide on the event model to use as soon as it creates watchers, and it	1099	decide on the event model to use as soon as it creates watchers, and it
740	might chose the wrong one unless you load the correct one yourself.	1100	might choose the wrong one unless you load the correct one yourself.
741		1101
742	You can chose to use a pure-perl implementation by loading the	1102	You can chose to use a pure-perl implementation by loading the
743	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1103	C<AnyEvent::Loop> module, which gives you similar behaviour
744	everywhere, but letting AnyEvent chose the model is generally better.	1104	everywhere, but letting AnyEvent chose the model is generally better.
745		1105
746	=head2 MAINLOOP EMULATION	1106	=head2 MAINLOOP EMULATION
747		1107
748	Sometimes (often for short test scripts, or even standalone programs who	1108	Sometimes (often for short test scripts, or even standalone programs who
…		…
761		1121
762		1122
763	=head1 OTHER MODULES	1123	=head1 OTHER MODULES
764		1124
765	The following is a non-exhaustive list of additional modules that use	1125	The following is a non-exhaustive list of additional modules that use
766	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1126	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
767	in the same program. Some of the modules come with AnyEvent, some are	1127	modules and other event loops in the same program. Some of the modules
768	available via CPAN.	1128	come as part of AnyEvent, the others are available via CPAN.
769		1129
770	=over 4	1130	=over 4
771		1131
772	=item L<AnyEvent::Util>	1132	=item L<AnyEvent::Util>
773		1133
774	Contains various utility functions that replace often-used but blocking	1134	Contains various utility functions that replace often-used blocking
775	functions such as C<inet_aton> by event-/callback-based versions.	1135	functions such as C<inet_aton> with event/callback-based versions.
776		1136
777	=item L<AnyEvent::Socket>	1137	=item L<AnyEvent::Socket>
778		1138
779	Provides various utility functions for (internet protocol) sockets,	1139	Provides various utility functions for (internet protocol) sockets,
780	addresses and name resolution. Also functions to create non-blocking tcp	1140	addresses and name resolution. Also functions to create non-blocking tcp
…		…
782		1142
783	=item L<AnyEvent::Handle>	1143	=item L<AnyEvent::Handle>
784		1144
785	Provide read and write buffers, manages watchers for reads and writes,	1145	Provide read and write buffers, manages watchers for reads and writes,
786	supports raw and formatted I/O, I/O queued and fully transparent and	1146	supports raw and formatted I/O, I/O queued and fully transparent and
787	non-blocking SSL/TLS.	1147	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
788		1148
789	=item L<AnyEvent::DNS>	1149	=item L<AnyEvent::DNS>
790		1150
791	Provides rich asynchronous DNS resolver capabilities.	1151	Provides rich asynchronous DNS resolver capabilities.
792		1152
		1153	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1154
		1155	Implement event-based interfaces to the protocols of the same name (for
		1156	the curious, IGS is the International Go Server and FCP is the Freenet
		1157	Client Protocol).
		1158
		1159	=item L<AnyEvent::Handle::UDP>
		1160
		1161	Here be danger!
		1162
		1163	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1164	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1165	its use of a stream-based API with a protocol that isn't streamable, that
		1166	the only way to improve it is to delete it.
		1167
		1168	It features data corruption (but typically only under load) and general
		1169	confusion. On top, the author is not only clueless about UDP but also
		1170	fact-resistant - some gems of his understanding: "connect doesn't work
		1171	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1172	packets", "I don't need to implement proper error checking as UDP doesn't
		1173	support error checking" and so on - he doesn't even understand what's
		1174	wrong with his module when it is explained to him.
		1175
793	=item L<AnyEvent::HTTP>	1176	=item L<AnyEvent::DBI>
794		1177
795	A simple-to-use HTTP library that is capable of making a lot of concurrent	1178	Executes L<DBI> requests asynchronously in a proxy process for you,
796	HTTP requests.	1179	notifying you in an event-based way when the operation is finished.
		1180
		1181	=item L<AnyEvent::AIO>
		1182
		1183	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1184	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1185	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1186	file I/O, and much more.
797		1187
798	=item L<AnyEvent::HTTPD>	1188	=item L<AnyEvent::HTTPD>
799		1189
800	Provides a simple web application server framework.	1190	A simple embedded webserver.
801		1191
802	=item L<AnyEvent::FastPing>	1192	=item L<AnyEvent::FastPing>
803		1193
804	The fastest ping in the west.	1194	The fastest ping in the west.
805		1195
806	=item L<AnyEvent::DBI>
807
808	Executes L<DBI> requests asynchronously in a proxy process.
809
810	=item L<AnyEvent::AIO>
811
812	Truly asynchronous I/O, should be in the toolbox of every event
813	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
814	together.
815
816	=item L<AnyEvent::BDB>
817
818	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
819	L<BDB> and AnyEvent together.
820
821	=item L<AnyEvent::GPSD>
822
823	A non-blocking interface to gpsd, a daemon delivering GPS information.
824
825	=item L<AnyEvent::IGS>
826
827	A non-blocking interface to the Internet Go Server protocol (used by
828	L<App::IGS>).
829
830	=item L<AnyEvent::IRC>
831
832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
833
834	=item L<Net::XMPP2>
835
836	AnyEvent based XMPP (Jabber protocol) module family.
837
838	=item L<Net::FCP>
839
840	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
841	of AnyEvent.
842
843	=item L<Event::ExecFlow>
844
845	High level API for event-based execution flow control.
846
847	=item L<Coro>	1196	=item L<Coro>
848		1197
849	Has special support for AnyEvent via L<Coro::AnyEvent>.	1198	Has special support for AnyEvent via L<Coro::AnyEvent>.
850		1199
851	=item L<IO::Lambda>
852
853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
854
855	=back	1200	=back
856		1201
857	=cut	1202	=cut
858		1203
859	package AnyEvent;	1204	package AnyEvent;
860		1205
861	no warnings;	1206	# basically a tuned-down version of common::sense
862	use strict qw(vars subs);	1207	sub common_sense {
		1208	# from common:.sense 3.4
		1209	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x3c\x3f\x33\x00\x0f\xf0\x0f\xc0\xf0\xfc\x33\x00";
		1210	# use strict vars subs - NO UTF-8, as Util.pm doesn't like this atm. (uts46data.pl)
		1211	$^H |= 0x00000600;
		1212	}
863		1213
		1214	BEGIN { AnyEvent::common_sense }
		1215
864	use Carp;	1216	use Carp ();
865		1217
866	our $VERSION = 4.32;	1218	our $VERSION = '6.01';
867	our $MODEL;	1219	our $MODEL;
868		1220
869	our $AUTOLOAD;
870	our @ISA;	1221	our @ISA;
871		1222
872	our @REGISTRY;	1223	our @REGISTRY;
873		1224
874	our $WIN32;	1225	our $VERBOSE;
875		1226
876	BEGIN {	1227	BEGIN {
877	my $win32 = ! ! ($^O =~ /mswin32/i);	1228	require "AnyEvent/constants.pl";
878	eval "sub WIN32(){ $win32 }";
879	}
880		1229
		1230	eval "sub TAINT (){" . (${^TAINT}*1) . "}";
		1231
		1232	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1233	if ${^TAINT};
		1234
881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1235	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1236	}
		1237
		1238	our $MAX_SIGNAL_LATENCY = 10;
882		1239
883	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1240	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
884		1241
885	{	1242	{
886	my $idx;	1243	my $idx;
887	$PROTOCOL{$_} = ++$idx	1244	$PROTOCOL{$_} = ++$idx
888	for reverse split /\s*,\s*/,	1245	for reverse split /\s*,\s*/,
889	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1246	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
890	}	1247	}
891		1248
		1249	our @post_detect;
		1250
		1251	sub post_detect(&) {
		1252	my ($cb) = @_;
		1253
		1254	push @post_detect, $cb;
		1255
		1256	defined wantarray
		1257	? bless \$cb, "AnyEvent::Util::postdetect"
		1258	: ()
		1259	}
		1260
		1261	sub AnyEvent::Util::postdetect::DESTROY {
		1262	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1263	}
		1264
		1265	our $POSTPONE_W;
		1266	our @POSTPONE;
		1267
		1268	sub _postpone_exec {
		1269	undef $POSTPONE_W;
		1270
		1271	&{ shift @POSTPONE }
		1272	while @POSTPONE;
		1273	}
		1274
		1275	sub postpone(&) {
		1276	push @POSTPONE, shift;
		1277
		1278	$POSTPONE_W ||= AE::timer (0, 0, \&_postpone_exec);
		1279
		1280	()
		1281	}
		1282
		1283	sub log($$;@) {
		1284	require AnyEvent::Log;
		1285	# AnyEvent::Log overwrites this function
		1286	goto &log;
		1287	}
		1288
892	my @models = (	1289	our @models = (
893	[EV:: => AnyEvent::Impl::EV::],	1290	[EV:: => AnyEvent::Impl::EV:: , 1],
894	[Event:: => AnyEvent::Impl::Event::],	1291	[AnyEvent::Loop:: => AnyEvent::Impl::Perl:: , 1],
895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
896	# everything below here will not be autoprobed	1292	# everything below here will not (normally) be autoprobed
897	# as the pureperl backend should work everywhere	1293	# as the pure perl backend should work everywhere
898	# and is usually faster	1294	# and is usually faster
		1295	[Event:: => AnyEvent::Impl::Event::, 1],
		1296	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1297	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1298	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1299	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1300	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1301	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
904	[Wx:: => AnyEvent::Impl::POE::],	1302	[Wx:: => AnyEvent::Impl::POE::],
905	[Prima:: => AnyEvent::Impl::POE::],	1303	[Prima:: => AnyEvent::Impl::POE::],
		1304	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # a bitch to autodetect
		1305	[Cocoa::EventLoop:: => AnyEvent::Impl::Cocoa::],
		1306	[FLTK:: => AnyEvent::Impl::FLTK2::],
906	);	1307	);
907		1308
908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1309	our @isa_hook;
909		1310
910	our @post_detect;	1311	sub _isa_set {
		1312	my @pkg = ("AnyEvent", (map $_->[0], grep defined, @isa_hook), $MODEL);
911		1313
		1314	@{"$pkg[$_-1]::ISA"} = $pkg[$_]
		1315	for 1 .. $#pkg;
		1316
		1317	grep $_ && $_->[1], @isa_hook
		1318	and AE::_reset ();
		1319	}
		1320
		1321	# used for hooking AnyEvent::Strict and AnyEvent::Debug::Wrap into the class hierarchy
		1322	sub _isa_hook($$;$) {
		1323	my ($i, $pkg, $reset_ae) = @_;
		1324
		1325	$isa_hook[$i] = $pkg ? [$pkg, $reset_ae] : undef;
		1326
		1327	_isa_set;
		1328	}
		1329
		1330	# all autoloaded methods reserve the complete glob, not just the method slot.
		1331	# due to bugs in perls method cache implementation.
		1332	our @methods = qw(io timer time now now_update signal child idle condvar);
		1333
912	sub post_detect(&) {	1334	sub detect() {
913	my ($cb) = @_;	1335	return $MODEL if $MODEL; # some programs keep references to detect
914		1336
915	if ($MODEL) {	1337	local $!; # for good measure
916	$cb->();	1338	local $SIG{__DIE__}; # we use eval
917		1339
918	1	1340	# free some memory
		1341	*detect = sub () { $MODEL };
		1342	# undef &func doesn't correctly update the method cache. grmbl.
		1343	# so we delete the whole glob. grmbl.
		1344	# otoh, perl doesn't let me undef an active usb, but it lets me free
		1345	# a glob with an active sub. hrm. i hope it works, but perl is
		1346	# usually buggy in this department. sigh.
		1347	delete @{"AnyEvent::"}{@methods};
		1348	undef @methods;
		1349
		1350	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z0-9:]+)$/) {
		1351	my $model = $1;
		1352	$model = "AnyEvent::Impl::$model" unless $model =~ s/::$//;
		1353	if (eval "require $model") {
		1354	$MODEL = $model;
		1355	AnyEvent::log 7 => "loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it."
		1356	if $VERBOSE >= 7;
919	} else {	1357	} else {
920	push @post_detect, $cb;	1358	AnyEvent::log warn => "unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@";
921		1359	}
922	defined wantarray
923	? bless \$cb, "AnyEvent::Util::PostDetect"
924	: ()
925	}	1360	}
926	}
927		1361
928	sub AnyEvent::Util::PostDetect::DESTROY {	1362	# check for already loaded models
929	@post_detect = grep $_ != ${$_[0]}, @post_detect;
930	}
931
932	sub detect() {
933	unless ($MODEL) {	1363	unless ($MODEL) {
934	no strict 'refs';	1364	for (@REGISTRY, @models) {
935	local $SIG{__DIE__};	1365	my ($package, $model) = @$_;
936		1366	if (${"$package\::VERSION"} > 0) {
937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
938	my $model = "AnyEvent::Impl::$1";
939	if (eval "require $model") {	1367	if (eval "require $model") {
940	$MODEL = $model;	1368	$MODEL = $model;
941	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1369	AnyEvent::log 7 => "autodetected model '$model', using it."
942	} else {	1370	if $VERBOSE >= 7;
943	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1371	last;
		1372	}
944	}	1373	}
945	}	1374	}
946		1375
947	# check for already loaded models
948	unless ($MODEL) {	1376	unless ($MODEL) {
		1377	# try to autoload a model
949	for (@REGISTRY, @models) {	1378	for (@REGISTRY, @models) {
950	my ($package, $model) = @$_;	1379	my ($package, $model, $autoload) = @$_;
		1380	if (
		1381	$autoload
		1382	and eval "require $package"
951	if (${"$package\::VERSION"} > 0) {	1383	and ${"$package\::VERSION"} > 0
952	if (eval "require $model") {	1384	and eval "require $model"
		1385	) {
953	$MODEL = $model;	1386	$MODEL = $model;
954	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1387	AnyEvent::log 7 => "autoloaded model '$model', using it."
		1388	if $VERBOSE >= 7;
955	last;	1389	last;
956	}
957	}	1390	}
958	}	1391	}
959		1392
960	unless ($MODEL) {
961	# try to load a model
962
963	for (@REGISTRY, @models) {
964	my ($package, $model) = @$_;
965	if (eval "require $package"
966	and ${"$package\::VERSION"} > 0
967	and eval "require $model") {
968	$MODEL = $model;
969	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
970	last;
971	}
972	}
973
974	$MODEL	1393	$MODEL
975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1394	or die "AnyEvent: backend autodetection failed - did you properly install AnyEvent?";
976	}
977	}	1395	}
978
979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
980
981	unshift @ISA, $MODEL;
982
983	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
984
985	(shift @post_detect)->() while @post_detect;
986	}	1396	}
987		1397
		1398	# free memory only needed for probing
		1399	undef @models;
		1400	undef @REGISTRY;
		1401
		1402	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1403
		1404	# now nuke some methods that are overridden by the backend.
		1405	# SUPER usage is not allowed in these.
		1406	for (qw(time signal child idle)) {
		1407	undef &{"AnyEvent::Base::$_"}
		1408	if defined &{"$MODEL\::$_"};
		1409	}
		1410
		1411	_isa_set;
		1412
		1413	if ($ENV{PERL_ANYEVENT_STRICT}) {
		1414	require AnyEvent::Strict;
		1415	}
		1416
		1417	if ($ENV{PERL_ANYEVENT_DEBUG_WRAP}) {
		1418	require AnyEvent::Debug;
		1419	AnyEvent::Debug::wrap ($ENV{PERL_ANYEVENT_DEBUG_WRAP});
		1420	}
		1421
		1422	if (exists $ENV{PERL_ANYEVENT_DEBUG_SHELL}) {
		1423	require AnyEvent::Socket;
		1424	require AnyEvent::Debug;
		1425
		1426	my $shell = $ENV{PERL_ANYEVENT_DEBUG_SHELL};
		1427	$shell =~ s/\$\$/$$/g;
		1428
		1429	my ($host, $service) = AnyEvent::Socket::parse_hostport ($shell);
		1430	$AnyEvent::Debug::SHELL = AnyEvent::Debug::shell ($host, $service);
		1431	}
		1432
		1433	(shift @post_detect)->() while @post_detect;
		1434	undef @post_detect;
		1435
		1436	*post_detect = sub(&) {
		1437	shift->();
		1438
		1439	undef
		1440	};
		1441
988	$MODEL	1442	$MODEL
989	}	1443	}
990		1444
991	sub AUTOLOAD {	1445	for my $name (@methods) {
992	(my $func = $AUTOLOAD) =~ s/.*://;	1446	*$name = sub {
993		1447	detect;
994	$method{$func}	1448	# we use goto because
995	or croak "$func: not a valid method for AnyEvent objects";	1449	# a) it makes the thunk more transparent
996		1450	# b) it allows us to delete the thunk later
997	detect unless $MODEL;	1451	goto &{ UNIVERSAL::can AnyEvent => "SUPER::$name" }
998		1452	};
999	my $class = shift;
1000	$class->$func (@_);
1001	}	1453	}
1002		1454
1003	# utility function to dup a filehandle. this is used by many backends	1455	# utility function to dup a filehandle. this is used by many backends
1004	# to support binding more than one watcher per filehandle (they usually	1456	# to support binding more than one watcher per filehandle (they usually
1005	# allow only one watcher per fd, so we dup it to get a different one).	1457	# allow only one watcher per fd, so we dup it to get a different one).
1006	sub _dupfh($$$$) {	1458	sub _dupfh($$;$$) {
1007	my ($poll, $fh, $r, $w) = @_;	1459	my ($poll, $fh, $r, $w) = @_;
1008		1460
1009	require Fcntl;
1010
1011	# cygwin requires the fh mode to be matching, unix doesn't	1461	# cygwin requires the fh mode to be matching, unix doesn't
1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1462	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1013	: $poll eq "w" ? ($w, ">")
1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1015		1463
1016	open my $fh2, "$mode&" . fileno $fh	1464	open my $fh2, $mode, $fh
1017	or die "cannot dup() filehandle: $!";	1465	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1018		1466
1019	# we assume CLOEXEC is already set by perl in all important cases	1467	# we assume CLOEXEC is already set by perl in all important cases
1020		1468
1021	($fh2, $rw)	1469	($fh2, $rw)
1022	}	1470	}
1023		1471
		1472	=head1 SIMPLIFIED AE API
		1473
		1474	Starting with version 5.0, AnyEvent officially supports a second, much
		1475	simpler, API that is designed to reduce the calling, typing and memory
		1476	overhead by using function call syntax and a fixed number of parameters.
		1477
		1478	See the L<AE> manpage for details.
		1479
		1480	=cut
		1481
		1482	package AE;
		1483
		1484	our $VERSION = $AnyEvent::VERSION;
		1485
		1486	sub _reset() {
		1487	eval q{
		1488	# fall back to the main API by default - backends and AnyEvent::Base
		1489	# implementations can overwrite these.
		1490
		1491	sub io($$$) {
		1492	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1493	}
		1494
		1495	sub timer($$$) {
		1496	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1497	}
		1498
		1499	sub signal($$) {
		1500	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1501	}
		1502
		1503	sub child($$) {
		1504	AnyEvent->child (pid => $_[0], cb => $_[1])
		1505	}
		1506
		1507	sub idle($) {
		1508	AnyEvent->idle (cb => $_[0]);
		1509	}
		1510
		1511	sub cv(;&) {
		1512	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1513	}
		1514
		1515	sub now() {
		1516	AnyEvent->now
		1517	}
		1518
		1519	sub now_update() {
		1520	AnyEvent->now_update
		1521	}
		1522
		1523	sub time() {
		1524	AnyEvent->time
		1525	}
		1526
		1527	*postpone = \&AnyEvent::postpone;
		1528	*log = \&AnyEvent::log;
		1529	};
		1530	die if $@;
		1531	}
		1532
		1533	BEGIN { _reset }
		1534
1024	package AnyEvent::Base;	1535	package AnyEvent::Base;
1025		1536
1026	# default implementation for now and time	1537	# default implementations for many methods
1027		1538
1028	BEGIN {	1539	sub time {
		1540	eval q{ # poor man's autoloading {}
		1541	# probe for availability of Time::HiRes
1029	if (eval "use Time::HiRes (); time (); 1") {	1542	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1543	AnyEvent::log 8 => "AnyEvent: using Time::HiRes for sub-second timing accuracy."
		1544	if $AnyEvent::VERBOSE >= 8;
		1545	*time = sub { Time::HiRes::time () };
1030	*_time = \&Time::HiRes::time;	1546	*AE::time = \& Time::HiRes::time ;
1031	# if (eval "use POSIX (); (POSIX::times())...	1547	# if (eval "use POSIX (); (POSIX::times())...
1032	} else {	1548	} else {
1033	*_time = sub { time }; # epic fail	1549	AnyEvent::log critical => "using built-in time(), WARNING, no sub-second resolution!";
		1550	*time = sub { CORE::time };
		1551	*AE::time = sub (){ CORE::time };
		1552	}
		1553
		1554	*now = \&time;
		1555	};
		1556	die if $@;
		1557
		1558	&time
		1559	}
		1560
		1561	*now = \&time;
		1562	sub now_update { }
		1563
		1564	sub _poll {
		1565	Carp::croak "$AnyEvent::MODEL does not support blocking waits. Caught";
		1566	}
		1567
		1568	# default implementation for ->condvar
		1569	# in fact, the default should not be overwritten
		1570
		1571	sub condvar {
		1572	eval q{ # poor man's autoloading {}
		1573	*condvar = sub {
		1574	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1575	};
		1576
		1577	*AE::cv = sub (;&) {
		1578	bless { @_ ? (_ae_cb => shift) : () }, "AnyEvent::CondVar"
		1579	};
		1580	};
		1581	die if $@;
		1582
		1583	&condvar
		1584	}
		1585
		1586	# default implementation for ->signal
		1587
		1588	our $HAVE_ASYNC_INTERRUPT;
		1589
		1590	sub _have_async_interrupt() {
		1591	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1592	&& eval "use Async::Interrupt 1.02 (); 1")
		1593	unless defined $HAVE_ASYNC_INTERRUPT;
		1594
		1595	$HAVE_ASYNC_INTERRUPT
		1596	}
		1597
		1598	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1599	our (%SIG_ASY, %SIG_ASY_W);
		1600	our ($SIG_COUNT, $SIG_TW);
		1601
		1602	# install a dummy wakeup watcher to reduce signal catching latency
		1603	# used by Impls
		1604	sub _sig_add() {
		1605	unless ($SIG_COUNT++) {
		1606	# try to align timer on a full-second boundary, if possible
		1607	my $NOW = AE::now;
		1608
		1609	$SIG_TW = AE::timer
		1610	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1611	$MAX_SIGNAL_LATENCY,
		1612	sub { } # just for the PERL_ASYNC_CHECK
		1613	;
1034	}	1614	}
1035	}	1615	}
1036		1616
1037	sub time { _time }	1617	sub _sig_del {
1038	sub now { _time }	1618	undef $SIG_TW
1039		1619	unless --$SIG_COUNT;
1040	# default implementation for ->condvar
1041
1042	sub condvar {
1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
1044	}	1620	}
1045		1621
1046	# default implementation for ->signal	1622	our $_sig_name_init; $_sig_name_init = sub {
		1623	eval q{ # poor man's autoloading {}
		1624	undef $_sig_name_init;
1047		1625
1048	our %SIG_CB;	1626	if (_have_async_interrupt) {
		1627	*sig2num = \&Async::Interrupt::sig2num;
		1628	*sig2name = \&Async::Interrupt::sig2name;
		1629	} else {
		1630	require Config;
		1631
		1632	my %signame2num;
		1633	@signame2num{ split ' ', $Config::Config{sig_name} }
		1634	= split ' ', $Config::Config{sig_num};
		1635
		1636	my @signum2name;
		1637	@signum2name[values %signame2num] = keys %signame2num;
		1638
		1639	*sig2num = sub($) {
		1640	$_[0] > 0 ? shift : $signame2num{+shift}
		1641	};
		1642	*sig2name = sub ($) {
		1643	$_[0] > 0 ? $signum2name[+shift] : shift
		1644	};
		1645	}
		1646	};
		1647	die if $@;
		1648	};
		1649
		1650	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1651	sub sig2name($) { &$_sig_name_init; &sig2name }
1049		1652
1050	sub signal {	1653	sub signal {
		1654	eval q{ # poor man's autoloading {}
		1655	# probe for availability of Async::Interrupt
		1656	if (_have_async_interrupt) {
		1657	AnyEvent::log 8 => "using Async::Interrupt for race-free signal handling."
		1658	if $AnyEvent::VERBOSE >= 8;
		1659
		1660	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1661	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1662
		1663	} else {
		1664	AnyEvent::log 8 => "using emulated perl signal handling with latency timer."
		1665	if $AnyEvent::VERBOSE >= 8;
		1666
		1667	if (AnyEvent::WIN32) {
		1668	require AnyEvent::Util;
		1669
		1670	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1671	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1672	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1673	} else {
		1674	pipe $SIGPIPE_R, $SIGPIPE_W;
		1675	fcntl $SIGPIPE_R, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_R;
		1676	fcntl $SIGPIPE_W, AnyEvent::F_SETFL, AnyEvent::O_NONBLOCK if $SIGPIPE_W; # just in case
		1677
		1678	# not strictly required, as $^F is normally 2, but let's make sure...
		1679	fcntl $SIGPIPE_R, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1680	fcntl $SIGPIPE_W, AnyEvent::F_SETFD, AnyEvent::FD_CLOEXEC;
		1681	}
		1682
		1683	$SIGPIPE_R
		1684	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1685
		1686	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1687	}
		1688
		1689	*signal = $HAVE_ASYNC_INTERRUPT
		1690	? sub {
1051	my (undef, %arg) = @_;	1691	my (undef, %arg) = @_;
1052		1692
		1693	# async::interrupt
1053	my $signal = uc $arg{signal}	1694	my $signal = sig2num $arg{signal};
1054	or Carp::croak "required option 'signal' is missing";
1055
1056	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1695	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1696
		1697	$SIG_ASY{$signal} ||= new Async::Interrupt
		1698	cb => sub { undef $SIG_EV{$signal} },
		1699	signal => $signal,
		1700	pipe => [$SIGPIPE_R->filenos],
		1701	pipe_autodrain => 0,
		1702	;
		1703
		1704	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1705	}
		1706	: sub {
		1707	my (undef, %arg) = @_;
		1708
		1709	# pure perl
		1710	my $signal = sig2name $arg{signal};
		1711	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1712
1057	$SIG{$signal} ||= sub {	1713	$SIG{$signal} ||= sub {
		1714	local $!;
		1715	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1716	undef $SIG_EV{$signal};
		1717	};
		1718
		1719	# can't do signal processing without introducing races in pure perl,
		1720	# so limit the signal latency.
		1721	_sig_add;
		1722
		1723	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1724	}
		1725	;
		1726
		1727	*AnyEvent::Base::signal::DESTROY = sub {
		1728	my ($signal, $cb) = @{$_[0]};
		1729
		1730	_sig_del;
		1731
		1732	delete $SIG_CB{$signal}{$cb};
		1733
		1734	$HAVE_ASYNC_INTERRUPT
		1735	? delete $SIG_ASY{$signal}
		1736	: # delete doesn't work with older perls - they then
		1737	# print weird messages, or just unconditionally exit
		1738	# instead of getting the default action.
		1739	undef $SIG{$signal}
		1740	unless keys %{ $SIG_CB{$signal} };
		1741	};
		1742
		1743	*_signal_exec = sub {
		1744	$HAVE_ASYNC_INTERRUPT
		1745	? $SIGPIPE_R->drain
		1746	: sysread $SIGPIPE_R, (my $dummy), 9;
		1747
		1748	while (%SIG_EV) {
		1749	for (keys %SIG_EV) {
		1750	delete $SIG_EV{$_};
1058	$_->() for values %{ $SIG_CB{$signal} || {} };	1751	&$_ for values %{ $SIG_CB{$_} || {} };
		1752	}
		1753	}
		1754	};
1059	};	1755	};
		1756	die if $@;
1060		1757
1061	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1758	&signal
1062	}
1063
1064	sub AnyEvent::Base::Signal::DESTROY {
1065	my ($signal, $cb) = @{$_[0]};
1066
1067	delete $SIG_CB{$signal}{$cb};
1068
1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1070	}	1759	}
1071		1760
1072	# default implementation for ->child	1761	# default implementation for ->child
1073		1762
1074	our %PID_CB;	1763	our %PID_CB;
1075	our $CHLD_W;	1764	our $CHLD_W;
1076	our $CHLD_DELAY_W;	1765	our $CHLD_DELAY_W;
1077	our $PID_IDLE;
1078	our $WNOHANG;
1079		1766
1080	sub _child_wait {	1767	# used by many Impl's
1081	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1768	sub _emit_childstatus($$) {
		1769	my (undef, $rpid, $rstatus) = @_;
		1770
		1771	$_->($rpid, $rstatus)
1082	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1772	for values %{ $PID_CB{$rpid} || {} },
1083	(values %{ $PID_CB{0} || {} });	1773	values %{ $PID_CB{0} || {} };
1084	}
1085
1086	undef $PID_IDLE;
1087	}
1088
1089	sub _sigchld {
1090	# make sure we deliver these changes "synchronous" with the event loop.
1091	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1092	undef $CHLD_DELAY_W;
1093	&_child_wait;
1094	});
1095	}	1774	}
1096		1775
1097	sub child {	1776	sub child {
		1777	eval q{ # poor man's autoloading {}
		1778	*_sigchld = sub {
		1779	my $pid;
		1780
		1781	AnyEvent->_emit_childstatus ($pid, $?)
		1782	while ($pid = waitpid -1, WNOHANG) > 0;
		1783	};
		1784
		1785	*child = sub {
1098	my (undef, %arg) = @_;	1786	my (undef, %arg) = @_;
1099		1787
1100	defined (my $pid = $arg{pid} + 0)	1788	my $pid = $arg{pid};
1101	or Carp::croak "required option 'pid' is missing";	1789	my $cb = $arg{cb};
1102		1790
1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1791	$PID_CB{$pid}{$cb+0} = $cb;
1104		1792
1105	unless ($WNOHANG) {
1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1107	}
1108
1109	unless ($CHLD_W) {	1793	unless ($CHLD_W) {
1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1794	$CHLD_W = AE::signal CHLD => \&_sigchld;
1111	# child could be a zombie already, so make at least one round	1795	# child could be a zombie already, so make at least one round
1112	&_sigchld;	1796	&_sigchld;
1113	}	1797	}
1114		1798
1115	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1799	bless [$pid, $cb+0], "AnyEvent::Base::child"
1116	}	1800	};
1117		1801
1118	sub AnyEvent::Base::Child::DESTROY {	1802	*AnyEvent::Base::child::DESTROY = sub {
1119	my ($pid, $cb) = @{$_[0]};	1803	my ($pid, $icb) = @{$_[0]};
1120		1804
1121	delete $PID_CB{$pid}{$cb};	1805	delete $PID_CB{$pid}{$icb};
1122	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1806	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1123		1807
1124	undef $CHLD_W unless keys %PID_CB;	1808	undef $CHLD_W unless keys %PID_CB;
		1809	};
		1810	};
		1811	die if $@;
		1812
		1813	&child
		1814	}
		1815
		1816	# idle emulation is done by simply using a timer, regardless
		1817	# of whether the process is idle or not, and not letting
		1818	# the callback use more than 50% of the time.
		1819	sub idle {
		1820	eval q{ # poor man's autoloading {}
		1821	*idle = sub {
		1822	my (undef, %arg) = @_;
		1823
		1824	my ($cb, $w, $rcb) = $arg{cb};
		1825
		1826	$rcb = sub {
		1827	if ($cb) {
		1828	$w = AE::time;
		1829	&$cb;
		1830	$w = AE::time - $w;
		1831
		1832	# never use more then 50% of the time for the idle watcher,
		1833	# within some limits
		1834	$w = 0.0001 if $w < 0.0001;
		1835	$w = 5 if $w > 5;
		1836
		1837	$w = AE::timer $w, 0, $rcb;
		1838	} else {
		1839	# clean up...
		1840	undef $w;
		1841	undef $rcb;
		1842	}
		1843	};
		1844
		1845	$w = AE::timer 0.05, 0, $rcb;
		1846
		1847	bless \\$cb, "AnyEvent::Base::idle"
		1848	};
		1849
		1850	*AnyEvent::Base::idle::DESTROY = sub {
		1851	undef $${$_[0]};
		1852	};
		1853	};
		1854	die if $@;
		1855
		1856	&idle
1125	}	1857	}
1126		1858
1127	package AnyEvent::CondVar;	1859	package AnyEvent::CondVar;
1128		1860
1129	our @ISA = AnyEvent::CondVar::Base::;	1861	our @ISA = AnyEvent::CondVar::Base::;
1130		1862
		1863	# only to be used for subclassing
		1864	sub new {
		1865	my $class = shift;
		1866	bless AnyEvent->condvar (@_), $class
		1867	}
		1868
1131	package AnyEvent::CondVar::Base;	1869	package AnyEvent::CondVar::Base;
1132		1870
1133	use overload	1871	#use overload
1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1872	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1135	fallback => 1;	1873	# fallback => 1;
		1874
		1875	# save 300+ kilobytes by dirtily hardcoding overloading
		1876	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1877	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1878	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1879	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1880
		1881	our $WAITING;
1136		1882
1137	sub _send {	1883	sub _send {
1138	# nop	1884	# nop
		1885	}
		1886
		1887	sub _wait {
		1888	AnyEvent->_poll until $_[0]{_ae_sent};
1139	}	1889	}
1140		1890
1141	sub send {	1891	sub send {
1142	my $cv = shift;	1892	my $cv = shift;
1143	$cv->{_ae_sent} = [@_];	1893	$cv->{_ae_sent} = [@_];
…		…
1152		1902
1153	sub ready {	1903	sub ready {
1154	$_[0]{_ae_sent}	1904	$_[0]{_ae_sent}
1155	}	1905	}
1156		1906
1157	sub _wait {
1158	AnyEvent->one_event while !$_[0]{_ae_sent};
1159	}
1160
1161	sub recv {	1907	sub recv {
		1908	unless ($_[0]{_ae_sent}) {
		1909	$WAITING
		1910	and Carp::croak "AnyEvent::CondVar: recursive blocking wait attempted";
		1911
		1912	local $WAITING = 1;
1162	$_[0]->_wait;	1913	$_[0]->_wait;
		1914	}
1163		1915
1164	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1916	$_[0]{_ae_croak}
1165	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1917	and Carp::croak $_[0]{_ae_croak};
		1918
		1919	wantarray
		1920	? @{ $_[0]{_ae_sent} }
		1921	: $_[0]{_ae_sent}[0]
1166	}	1922	}
1167		1923
1168	sub cb {	1924	sub cb {
1169	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1925	my $cv = shift;
		1926
		1927	@_
		1928	and $cv->{_ae_cb} = shift
		1929	and $cv->{_ae_sent}
		1930	and (delete $cv->{_ae_cb})->($cv);
		1931
1170	$_[0]{_ae_cb}	1932	$cv->{_ae_cb}
1171	}	1933	}
1172		1934
1173	sub begin {	1935	sub begin {
1174	++$_[0]{_ae_counter};	1936	++$_[0]{_ae_counter};
1175	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1937	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1180	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };	1942	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
1181	}	1943	}
1182		1944
1183	# undocumented/compatibility with pre-3.4	1945	# undocumented/compatibility with pre-3.4
1184	*broadcast = \&send;	1946	*broadcast = \&send;
1185	*wait = \&_wait;	1947	*wait = \&recv;
1186		1948
1187	=head1 ERROR AND EXCEPTION HANDLING	1949	=head1 ERROR AND EXCEPTION HANDLING
1188		1950
1189	In general, AnyEvent does not do any error handling - it relies on the	1951	In general, AnyEvent does not do any error handling - it relies on the
1190	caller to do that if required. The L<AnyEvent::Strict> module (see also	1952	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1203	so on.	1965	so on.
1204		1966
1205	=head1 ENVIRONMENT VARIABLES	1967	=head1 ENVIRONMENT VARIABLES
1206		1968
1207	The following environment variables are used by this module or its	1969	The following environment variables are used by this module or its
1208	submodules:	1970	submodules.
		1971
		1972	Note that AnyEvent will remove I<all> environment variables starting with
		1973	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1974	enabled.
1209		1975
1210	=over 4	1976	=over 4
1211		1977
1212	=item C<PERL_ANYEVENT_VERBOSE>	1978	=item C<PERL_ANYEVENT_VERBOSE>
1213		1979
1214	By default, AnyEvent will be completely silent except in fatal	1980	By default, AnyEvent will be completely silent except in fatal
1215	conditions. You can set this environment variable to make AnyEvent more	1981	conditions. You can set this environment variable to make AnyEvent more
1216	talkative.	1982	talkative.
1217		1983
1218	When set to C<1> or higher, causes AnyEvent to warn about unexpected	1984	When set to C<5> or higher, causes AnyEvent to warn about unexpected
1219	conditions, such as not being able to load the event model specified by	1985	conditions, such as not being able to load the event model specified by
1220	C<PERL_ANYEVENT_MODEL>.	1986	C<PERL_ANYEVENT_MODEL>.
1221		1987
1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1988	When set to C<7> or higher, cause AnyEvent to report to STDERR which event
1223	model it chooses.	1989	model it chooses.
		1990
		1991	When set to C<8> or higher, then AnyEvent will report extra information on
		1992	which optional modules it loads and how it implements certain features.
1224		1993
1225	=item C<PERL_ANYEVENT_STRICT>	1994	=item C<PERL_ANYEVENT_STRICT>
1226		1995
1227	AnyEvent does not do much argument checking by default, as thorough	1996	AnyEvent does not do much argument checking by default, as thorough
1228	argument checking is very costly. Setting this variable to a true value	1997	argument checking is very costly. Setting this variable to a true value
1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1998	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1230	check the arguments passed to most method calls. If it finds any problems	1999	check the arguments passed to most method calls. If it finds any problems,
1231	it will croak.	2000	it will croak.
1232		2001
1233	In other words, enables "strict" mode.	2002	In other words, enables "strict" mode.
1234		2003
1235	Unlike C<use strict>, it is definitely recommended ot keep it off in	2004	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	2005	>>, it is definitely recommended to keep it off in production. Keeping
1237	developing programs can be very useful, however.	2006	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		2007	can be very useful, however.
		2008
		2009	=item C<PERL_ANYEVENT_DEBUG_SHELL>
		2010
		2011	If this env variable is set, then its contents will be interpreted by
		2012	C<AnyEvent::Socket::parse_hostport> (after replacing every occurance of
		2013	C<$$> by the process pid) and an C<AnyEvent::Debug::shell> is bound on
		2014	that port. The shell object is saved in C<$AnyEvent::Debug::SHELL>.
		2015
		2016	This takes place when the first watcher is created.
		2017
		2018	For example, to bind a debug shell on a unix domain socket in
		2019	F<< /tmp/debug<pid>.sock >>, you could use this:
		2020
		2021	PERL_ANYEVENT_DEBUG_SHELL=/tmp/debug\$\$.sock perlprog
		2022
		2023	Note that creating sockets in F</tmp> is very unsafe on multiuser
		2024	systems.
		2025
		2026	=item C<PERL_ANYEVENT_DEBUG_WRAP>
		2027
		2028	Can be set to C<0>, C<1> or C<2> and enables wrapping of all watchers for
		2029	debugging purposes. See C<AnyEvent::Debug::wrap> for details.
1238		2030
1239	=item C<PERL_ANYEVENT_MODEL>	2031	=item C<PERL_ANYEVENT_MODEL>
1240		2032
1241	This can be used to specify the event model to be used by AnyEvent, before	2033	This can be used to specify the event model to be used by AnyEvent, before
1242	auto detection and -probing kicks in. It must be a string consisting	2034	auto detection and -probing kicks in.
1243	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	2035
		2036	It normally is a string consisting entirely of ASCII letters (e.g. C<EV>
		2037	or C<IOAsync>). The string C<AnyEvent::Impl::> gets prepended and the
1244	and the resulting module name is loaded and if the load was successful,	2038	resulting module name is loaded and - if the load was successful - used as
1245	used as event model. If it fails to load AnyEvent will proceed with	2039	event model backend. If it fails to load then AnyEvent will proceed with
1246	auto detection and -probing.	2040	auto detection and -probing.
1247		2041
1248	This functionality might change in future versions.	2042	If the string ends with C<::> instead (e.g. C<AnyEvent::Impl::EV::>) then
		2043	nothing gets prepended and the module name is used as-is (hint: C<::> at
		2044	the end of a string designates a module name and quotes it appropriately).
1249		2045
1250	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	2046	For example, to force the pure perl model (L<AnyEvent::Loop::Perl>) you
1251	could start your program like this:	2047	could start your program like this:
1252		2048
1253	PERL_ANYEVENT_MODEL=Perl perl ...	2049	PERL_ANYEVENT_MODEL=Perl perl ...
1254		2050
1255	=item C<PERL_ANYEVENT_PROTOCOLS>	2051	=item C<PERL_ANYEVENT_PROTOCOLS>
…		…
1263	used, and preference will be given to protocols mentioned earlier in the	2059	used, and preference will be given to protocols mentioned earlier in the
1264	list.	2060	list.
1265		2061
1266	This variable can effectively be used for denial-of-service attacks	2062	This variable can effectively be used for denial-of-service attacks
1267	against local programs (e.g. when setuid), although the impact is likely	2063	against local programs (e.g. when setuid), although the impact is likely
1268	small, as the program has to handle connection errors already-	2064	small, as the program has to handle conenction and other failures anyways.
1269		2065
1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,	2066	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	2067	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1272	- only support IPv4, never try to resolve or contact IPv6	2068	- only support IPv4, never try to resolve or contact IPv6
1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	2069	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
…		…
1285		2081
1286	=item C<PERL_ANYEVENT_MAX_FORKS>	2082	=item C<PERL_ANYEVENT_MAX_FORKS>
1287		2083
1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>	2084	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1289	will create in parallel.	2085	will create in parallel.
		2086
		2087	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		2088
		2089	The default value for the C<max_outstanding> parameter for the default DNS
		2090	resolver - this is the maximum number of parallel DNS requests that are
		2091	sent to the DNS server.
		2092
		2093	=item C<PERL_ANYEVENT_RESOLV_CONF>
		2094
		2095	The file to use instead of F</etc/resolv.conf> (or OS-specific
		2096	configuration) in the default resolver. When set to the empty string, no
		2097	default config will be used.
		2098
		2099	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		2100
		2101	When neither C<ca_file> nor C<ca_path> was specified during
		2102	L<AnyEvent::TLS> context creation, and either of these environment
		2103	variables exist, they will be used to specify CA certificate locations
		2104	instead of a system-dependent default.
		2105
		2106	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		2107
		2108	When these are set to C<1>, then the respective modules are not
		2109	loaded. Mostly good for testing AnyEvent itself.
1290		2110
1291	=back	2111	=back
1292		2112
1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	2113	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1294		2114
…		…
1352	warn "read: $input\n"; # output what has been read	2172	warn "read: $input\n"; # output what has been read
1353	$cv->send if $input =~ /^q/i; # quit program if /^q/i	2173	$cv->send if $input =~ /^q/i; # quit program if /^q/i
1354	},	2174	},
1355	);	2175	);
1356		2176
1357	my $time_watcher; # can only be used once
1358
1359	sub new_timer {
1360	$timer = AnyEvent->timer (after => 1, cb => sub {	2177	my $time_watcher = AnyEvent->timer (after => 1, interval => 1, cb => sub {
1361	warn "timeout\n"; # print 'timeout' about every second	2178	warn "timeout\n"; # print 'timeout' at most every second
1362	&new_timer; # and restart the time
1363	});	2179	});
1364	}
1365
1366	new_timer; # create first timer
1367		2180
1368	$cv->recv; # wait until user enters /^q/i	2181	$cv->recv; # wait until user enters /^q/i
1369		2182
1370	=head1 REAL-WORLD EXAMPLE	2183	=head1 REAL-WORLD EXAMPLE
1371		2184
…		…
1444		2257
1445	The actual code goes further and collects all errors (C<die>s, exceptions)	2258	The actual code goes further and collects all errors (C<die>s, exceptions)
1446	that occurred during request processing. The C<result> method detects	2259	that occurred during request processing. The C<result> method detects
1447	whether an exception as thrown (it is stored inside the $txn object)	2260	whether an exception as thrown (it is stored inside the $txn object)
1448	and just throws the exception, which means connection errors and other	2261	and just throws the exception, which means connection errors and other
1449	problems get reported tot he code that tries to use the result, not in a	2262	problems get reported to the code that tries to use the result, not in a
1450	random callback.	2263	random callback.
1451		2264
1452	All of this enables the following usage styles:	2265	All of this enables the following usage styles:
1453		2266
1454	1. Blocking:	2267	1. Blocking:
…		…
1502	through AnyEvent. The benchmark creates a lot of timers (with a zero	2315	through AnyEvent. The benchmark creates a lot of timers (with a zero
1503	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2316	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1504	which it is), lets them fire exactly once and destroys them again.	2317	which it is), lets them fire exactly once and destroys them again.
1505		2318
1506	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2319	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1507	distribution.	2320	distribution. It uses the L<AE> interface, which makes a real difference
		2321	for the EV and Perl backends only.
1508		2322
1509	=head3 Explanation of the columns	2323	=head3 Explanation of the columns
1510		2324
1511	I<watcher> is the number of event watchers created/destroyed. Since	2325	I<watcher> is the number of event watchers created/destroyed. Since
1512	different event models feature vastly different performances, each event	2326	different event models feature vastly different performances, each event
…		…
1533	watcher.	2347	watcher.
1534		2348
1535	=head3 Results	2349	=head3 Results
1536		2350
1537	name watchers bytes create invoke destroy comment	2351	name watchers bytes create invoke destroy comment
1538	EV/EV 400000 224 0.47 0.35 0.27 EV native interface	2352	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1539	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2353	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1540	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2354	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1541	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2355	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1542	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2356	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1543	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2357	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2358	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2359	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1544	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2360	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1545	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2361	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1546	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2362	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1547	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2363	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1548		2364
1549	=head3 Discussion	2365	=head3 Discussion
1550		2366
1551	The benchmark does I<not> measure scalability of the event loop very	2367	The benchmark does I<not> measure scalability of the event loop very
1552	well. For example, a select-based event loop (such as the pure perl one)	2368	well. For example, a select-based event loop (such as the pure perl one)
…		…
1564	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2380	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1565	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2381	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1566	cycles with POE.	2382	cycles with POE.
1567		2383
1568	C<EV> is the sole leader regarding speed and memory use, which are both	2384	C<EV> is the sole leader regarding speed and memory use, which are both
1569	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2385	maximal/minimal, respectively. When using the L<AE> API there is zero
		2386	overhead (when going through the AnyEvent API create is about 5-6 times
		2387	slower, with other times being equal, so still uses far less memory than
1570	far less memory than any other event loop and is still faster than Event	2388	any other event loop and is still faster than Event natively).
1571	natively.
1572		2389
1573	The pure perl implementation is hit in a few sweet spots (both the	2390	The pure perl implementation is hit in a few sweet spots (both the
1574	constant timeout and the use of a single fd hit optimisations in the perl	2391	constant timeout and the use of a single fd hit optimisations in the perl
1575	interpreter and the backend itself). Nevertheless this shows that it	2392	interpreter and the backend itself). Nevertheless this shows that it
1576	adds very little overhead in itself. Like any select-based backend its	2393	adds very little overhead in itself. Like any select-based backend its
1577	performance becomes really bad with lots of file descriptors (and few of	2394	performance becomes really bad with lots of file descriptors (and few of
1578	them active), of course, but this was not subject of this benchmark.	2395	them active), of course, but this was not subject of this benchmark.
1579		2396
1580	The C<Event> module has a relatively high setup and callback invocation	2397	The C<Event> module has a relatively high setup and callback invocation
1581	cost, but overall scores in on the third place.	2398	cost, but overall scores in on the third place.
		2399
		2400	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2401	when using its pure perl backend.
1582		2402
1583	C<Glib>'s memory usage is quite a bit higher, but it features a	2403	C<Glib>'s memory usage is quite a bit higher, but it features a
1584	faster callback invocation and overall ends up in the same class as	2404	faster callback invocation and overall ends up in the same class as
1585	C<Event>. However, Glib scales extremely badly, doubling the number of	2405	C<Event>. However, Glib scales extremely badly, doubling the number of
1586	watchers increases the processing time by more than a factor of four,	2406	watchers increases the processing time by more than a factor of four,
…		…
1621	(even when used without AnyEvent), but most event loops have acceptable	2441	(even when used without AnyEvent), but most event loops have acceptable
1622	performance with or without AnyEvent.	2442	performance with or without AnyEvent.
1623		2443
1624	=item * The overhead AnyEvent adds is usually much smaller than the overhead of	2444	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1625	the actual event loop, only with extremely fast event loops such as EV	2445	the actual event loop, only with extremely fast event loops such as EV
1626	adds AnyEvent significant overhead.	2446	does AnyEvent add significant overhead.
1627		2447
1628	=item * You should avoid POE like the plague if you want performance or	2448	=item * You should avoid POE like the plague if you want performance or
1629	reasonable memory usage.	2449	reasonable memory usage.
1630		2450
1631	=back	2451	=back
…		…
1647	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2467	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1648	(1%) are active. This mirrors the activity of large servers with many	2468	(1%) are active. This mirrors the activity of large servers with many
1649	connections, most of which are idle at any one point in time.	2469	connections, most of which are idle at any one point in time.
1650		2470
1651	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2471	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1652	distribution.	2472	distribution. It uses the L<AE> interface, which makes a real difference
		2473	for the EV and Perl backends only.
1653		2474
1654	=head3 Explanation of the columns	2475	=head3 Explanation of the columns
1655		2476
1656	I<sockets> is the number of sockets, and twice the number of "servers" (as	2477	I<sockets> is the number of sockets, and twice the number of "servers" (as
1657	each server has a read and write socket end).	2478	each server has a read and write socket end).
…		…
1664	it to another server. This includes deleting the old timeout and creating	2485	it to another server. This includes deleting the old timeout and creating
1665	a new one that moves the timeout into the future.	2486	a new one that moves the timeout into the future.
1666		2487
1667	=head3 Results	2488	=head3 Results
1668		2489
1669	name sockets create request	2490	name sockets create request
1670	EV 20000 69.01 11.16	2491	EV 20000 62.66 7.99
1671	Perl 20000 73.32 35.87	2492	Perl 20000 68.32 32.64
1672	Event 20000 212.62 257.32	2493	IOAsync 20000 174.06 101.15 epoll
1673	Glib 20000 651.16 1896.30	2494	IOAsync 20000 174.67 610.84 poll
		2495	Event 20000 202.69 242.91
		2496	Glib 20000 557.01 1689.52
1674	POE 20000 349.67 12317.24 uses POE::Loop::Event	2497	POE 20000 341.54 12086.32 uses POE::Loop::Event
1675		2498
1676	=head3 Discussion	2499	=head3 Discussion
1677		2500
1678	This benchmark I<does> measure scalability and overall performance of the	2501	This benchmark I<does> measure scalability and overall performance of the
1679	particular event loop.	2502	particular event loop.
…		…
1681	EV is again fastest. Since it is using epoll on my system, the setup time	2504	EV is again fastest. Since it is using epoll on my system, the setup time
1682	is relatively high, though.	2505	is relatively high, though.
1683		2506
1684	Perl surprisingly comes second. It is much faster than the C-based event	2507	Perl surprisingly comes second. It is much faster than the C-based event
1685	loops Event and Glib.	2508	loops Event and Glib.
		2509
		2510	IO::Async performs very well when using its epoll backend, and still quite
		2511	good compared to Glib when using its pure perl backend.
1686		2512
1687	Event suffers from high setup time as well (look at its code and you will	2513	Event suffers from high setup time as well (look at its code and you will
1688	understand why). Callback invocation also has a high overhead compared to	2514	understand why). Callback invocation also has a high overhead compared to
1689	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2515	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1690	uses select or poll in basically all documented configurations.	2516	uses select or poll in basically all documented configurations.
…		…
1753	=item * C-based event loops perform very well with small number of	2579	=item * C-based event loops perform very well with small number of
1754	watchers, as the management overhead dominates.	2580	watchers, as the management overhead dominates.
1755		2581
1756	=back	2582	=back
1757		2583
		2584	=head2 THE IO::Lambda BENCHMARK
		2585
		2586	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2587	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2588	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2589	shouldn't come as a surprise to anybody). As such, the benchmark is
		2590	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2591	very optimal. But how would AnyEvent compare when used without the extra
		2592	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2593
		2594	The benchmark itself creates an echo-server, and then, for 500 times,
		2595	connects to the echo server, sends a line, waits for the reply, and then
		2596	creates the next connection. This is a rather bad benchmark, as it doesn't
		2597	test the efficiency of the framework or much non-blocking I/O, but it is a
		2598	benchmark nevertheless.
		2599
		2600	name runtime
		2601	Lambda/select 0.330 sec
		2602	+ optimized 0.122 sec
		2603	Lambda/AnyEvent 0.327 sec
		2604	+ optimized 0.138 sec
		2605	Raw sockets/select 0.077 sec
		2606	POE/select, components 0.662 sec
		2607	POE/select, raw sockets 0.226 sec
		2608	POE/select, optimized 0.404 sec
		2609
		2610	AnyEvent/select/nb 0.085 sec
		2611	AnyEvent/EV/nb 0.068 sec
		2612	+state machine 0.134 sec
		2613
		2614	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2615	benchmarks actually make blocking connects and use 100% blocking I/O,
		2616	defeating the purpose of an event-based solution. All of the newly
		2617	written AnyEvent benchmarks use 100% non-blocking connects (using
		2618	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2619	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2620	generally require a lot more bookkeeping and event handling than blocking
		2621	connects (which involve a single syscall only).
		2622
		2623	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2624	offers similar expressive power as POE and IO::Lambda, using conventional
		2625	Perl syntax. This means that both the echo server and the client are 100%
		2626	non-blocking, further placing it at a disadvantage.
		2627
		2628	As you can see, the AnyEvent + EV combination even beats the
		2629	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2630	backend easily beats IO::Lambda and POE.
		2631
		2632	And even the 100% non-blocking version written using the high-level (and
		2633	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda
		2634	higher level ("unoptimised") abstractions by a large margin, even though
		2635	it does all of DNS, tcp-connect and socket I/O in a non-blocking way.
		2636
		2637	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2638	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2639	part of the IO::Lambda distribution and were used without any changes.
		2640
1758		2641
1759	=head1 SIGNALS	2642	=head1 SIGNALS
1760		2643
1761	AnyEvent currently installs handlers for these signals:	2644	AnyEvent currently installs handlers for these signals:
1762		2645
…		…
1765	=item SIGCHLD	2648	=item SIGCHLD
1766		2649
1767	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2650	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1768	emulation for event loops that do not support them natively. Also, some	2651	emulation for event loops that do not support them natively. Also, some
1769	event loops install a similar handler.	2652	event loops install a similar handler.
		2653
		2654	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2655	AnyEvent will reset it to default, to avoid losing child exit statuses.
1770		2656
1771	=item SIGPIPE	2657	=item SIGPIPE
1772		2658
1773	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2659	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1774	when AnyEvent gets loaded.	2660	when AnyEvent gets loaded.
…		…
1786		2672
1787	=back	2673	=back
1788		2674
1789	=cut	2675	=cut
1790		2676
		2677	undef $SIG{CHLD}
		2678	if $SIG{CHLD} eq 'IGNORE';
		2679
1791	$SIG{PIPE} = sub { }	2680	$SIG{PIPE} = sub { }
1792	unless defined $SIG{PIPE};	2681	unless defined $SIG{PIPE};
1793		2682
		2683	=head1 RECOMMENDED/OPTIONAL MODULES
		2684
		2685	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2686	its built-in modules) are required to use it.
		2687
		2688	That does not mean that AnyEvent won't take advantage of some additional
		2689	modules if they are installed.
		2690
		2691	This section explains which additional modules will be used, and how they
		2692	affect AnyEvent's operation.
		2693
		2694	=over 4
		2695
		2696	=item L<Async::Interrupt>
		2697
		2698	This slightly arcane module is used to implement fast signal handling: To
		2699	my knowledge, there is no way to do completely race-free and quick
		2700	signal handling in pure perl. To ensure that signals still get
		2701	delivered, AnyEvent will start an interval timer to wake up perl (and
		2702	catch the signals) with some delay (default is 10 seconds, look for
		2703	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2704
		2705	If this module is available, then it will be used to implement signal
		2706	catching, which means that signals will not be delayed, and the event loop
		2707	will not be interrupted regularly, which is more efficient (and good for
		2708	battery life on laptops).
		2709
		2710	This affects not just the pure-perl event loop, but also other event loops
		2711	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2712
		2713	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2714	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2715	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2716	does nothing for those backends.
		2717
		2718	=item L<EV>
		2719
		2720	This module isn't really "optional", as it is simply one of the backend
		2721	event loops that AnyEvent can use. However, it is simply the best event
		2722	loop available in terms of features, speed and stability: It supports
		2723	the AnyEvent API optimally, implements all the watcher types in XS, does
		2724	automatic timer adjustments even when no monotonic clock is available,
		2725	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2726	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2727	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2728
		2729	If you only use backends that rely on another event loop (e.g. C<Tk>),
		2730	then this module will do nothing for you.
		2731
		2732	=item L<Guard>
		2733
		2734	The guard module, when used, will be used to implement
		2735	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2736	lot less memory), but otherwise doesn't affect guard operation much. It is
		2737	purely used for performance.
		2738
		2739	=item L<JSON> and L<JSON::XS>
		2740
		2741	One of these modules is required when you want to read or write JSON data
		2742	via L<AnyEvent::Handle>. L<JSON> is also written in pure-perl, but can take
		2743	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2744
		2745	=item L<Net::SSLeay>
		2746
		2747	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2748	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2749	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2750
		2751	=item L<Time::HiRes>
		2752
		2753	This module is part of perl since release 5.008. It will be used when the
		2754	chosen event library does not come with a timing source of its own. The
		2755	pure-perl event loop (L<AnyEvent::Loop>) will additionally load it to
		2756	try to use a monotonic clock for timing stability.
		2757
		2758	=back
		2759
1794		2760
1795	=head1 FORK	2761	=head1 FORK
1796		2762
1797	Most event libraries are not fork-safe. The ones who are usually are	2763	Most event libraries are not fork-safe. The ones who are usually are
1798	because they rely on inefficient but fork-safe C<select> or C<poll>	2764	because they rely on inefficient but fork-safe C<select> or C<poll> calls
1799	calls. Only L<EV> is fully fork-aware.	2765	- higher performance APIs such as BSD's kqueue or the dreaded Linux epoll
		2766	are usually badly thought-out hacks that are incompatible with fork in
		2767	one way or another. Only L<EV> is fully fork-aware and ensures that you
		2768	continue event-processing in both parent and child (or both, if you know
		2769	what you are doing).
		2770
		2771	This means that, in general, you cannot fork and do event processing in
		2772	the child if the event library was initialised before the fork (which
		2773	usually happens when the first AnyEvent watcher is created, or the library
		2774	is loaded).
1800		2775
1801	If you have to fork, you must either do so I<before> creating your first	2776	If you have to fork, you must either do so I<before> creating your first
1802	watcher OR you must not use AnyEvent at all in the child.	2777	watcher OR you must not use AnyEvent at all in the child OR you must do
		2778	something completely out of the scope of AnyEvent.
		2779
		2780	The problem of doing event processing in the parent I<and> the child
		2781	is much more complicated: even for backends that I<are> fork-aware or
		2782	fork-safe, their behaviour is not usually what you want: fork clones all
		2783	watchers, that means all timers, I/O watchers etc. are active in both
		2784	parent and child, which is almost never what you want. USing C<exec>
		2785	to start worker children from some kind of manage rprocess is usually
		2786	preferred, because it is much easier and cleaner, at the expense of having
		2787	to have another binary.
1803		2788
1804		2789
1805	=head1 SECURITY CONSIDERATIONS	2790	=head1 SECURITY CONSIDERATIONS
1806		2791
1807	AnyEvent can be forced to load any event model via	2792	AnyEvent can be forced to load any event model via
…		…
1819	use AnyEvent;	2804	use AnyEvent;
1820		2805
1821	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2806	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1822	be used to probe what backend is used and gain other information (which is	2807	be used to probe what backend is used and gain other information (which is
1823	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2808	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1824	$ENV{PERL_ANYEGENT_STRICT}.	2809	$ENV{PERL_ANYEVENT_STRICT}.
		2810
		2811	Note that AnyEvent will remove I<all> environment variables starting with
		2812	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2813	enabled.
1825		2814
1826		2815
1827	=head1 BUGS	2816	=head1 BUGS
1828		2817
1829	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2818	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1830	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2819	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1831	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2820	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1832	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2821	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1833	pronounced).	2822	pronounced).
1834		2823
1835		2824
1836	=head1 SEE ALSO	2825	=head1 SEE ALSO
1837		2826
1838	Utility functions: L<AnyEvent::Util>.	2827	Tutorial/Introduction: L<AnyEvent::Intro>.
1839		2828
1840	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,	2829	FAQ: L<AnyEvent::FAQ>.
1841	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2830
		2831	Utility functions: L<AnyEvent::Util> (misc. grab-bag), L<AnyEvent::Log>
		2832	(simply logging).
		2833
		2834	Development/Debugging: L<AnyEvent::Strict> (stricter checking),
		2835	L<AnyEvent::Debug> (interactive shell, watcher tracing).
		2836
		2837	Supported event modules: L<AnyEvent::Loop>, L<EV>, L<EV::Glib>,
		2838	L<Glib::EV>, L<Event>, L<Glib::Event>, L<Glib>, L<Tk>, L<Event::Lib>,
		2839	L<Qt>, L<POE>, L<FLTK>.
1842		2840
1843	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2841	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1844	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2842	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1845	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2843	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		2844	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>,
1846	L<AnyEvent::Impl::POE>.	2845	L<AnyEvent::Impl::FLTK>.
1847		2846
1848	Non-blocking file handles, sockets, TCP clients and	2847	Non-blocking handles, pipes, stream sockets, TCP clients and
1849	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2848	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1850		2849
1851	Asynchronous DNS: L<AnyEvent::DNS>.	2850	Asynchronous DNS: L<AnyEvent::DNS>.
1852		2851
1853	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2852	Thread support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>.
1854		2853
1855	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2854	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::IRC>,
		2855	L<AnyEvent::HTTP>.
1856		2856
1857		2857
1858	=head1 AUTHOR	2858	=head1 AUTHOR
1859		2859
1860	Marc Lehmann <schmorp@schmorp.de>	2860	Marc Lehmann <schmorp@schmorp.de>

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