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Revision 1.93 by root, Sat Apr 26 04:19:52 2008 UTC vs.
Revision 1.202 by root, Wed Apr 1 15:29:00 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });
		12
		13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
12	...	23	...
13	});	24	});
14		25
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...
17	});
18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		27	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	28	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
		31
		32	=head1 INTRODUCTION/TUTORIAL
		33
		34	This manpage is mainly a reference manual. If you are interested
		35	in a tutorial or some gentle introduction, have a look at the
		36	L<AnyEvent::Intro> manpage.
22		37
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		39
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	41	nowadays. So what is different about AnyEvent?
27		42
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
30		45
31	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	48	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	49	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	50	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
37		53
38	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	56	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	57	module users into the same thing by forcing them to use the same event
42	model you use.	58	model you use.
43		59
44	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	63	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	64	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	65	module are I<also> forced to use the same event loop you use.
50		66
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
59		75
60	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	80	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	81	technically possible.
66		82
		83	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		84	of useful functionality, such as an asynchronous DNS resolver, 100%
		85	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		86	such as Windows) and lots of real-world knowledge and workarounds for
		87	platform bugs and differences.
		88
67	Of course, if you want lots of policy (this can arguably be somewhat	89	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	90	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	91	model, you should I<not> use this module.
70
71		92
72	=head1 DESCRIPTION	93	=head1 DESCRIPTION
73		94
74	L<AnyEvent> provides an identical interface to multiple event loops. This	95	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	96	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	100	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	101	module.
81		102
82	During the first call of any watcher-creation method, the module tries	103	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	104	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	105	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	106	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	107	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	108	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	109	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	110	be successfully loaded will be used. If, after this, still none could be
…		…
103	starts using it, all bets are off. Maybe you should tell their authors to	124	starts using it, all bets are off. Maybe you should tell their authors to
104	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
105		126
106	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	128	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
109		130
110	=head1 WATCHERS	131	=head1 WATCHERS
111		132
112	AnyEvent has the central concept of a I<watcher>, which is an object that	133	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	134	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
115		136
116	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	138	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	139	callback when the event occurs (of course, only when the event model
119	is in control).	140	is in control).
120		141
		142	Note that B<callbacks must not permanently change global variables>
		143	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		144	callbacks must not C<die> >>. The former is good programming practise in
		145	Perl and the latter stems from the fact that exception handling differs
		146	widely between event loops.
		147
121	To disable the watcher you have to destroy it (e.g. by setting the	148	To disable the watcher you have to destroy it (e.g. by setting the
122	variable you store it in to C<undef> or otherwise deleting all references	149	variable you store it in to C<undef> or otherwise deleting all references
123	to it).	150	to it).
124		151
125	All watchers are created by calling a method on the C<AnyEvent> class.	152	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
127	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
128	example), or need to refer to their watcher object in other ways.	155	example), or need to refer to their watcher object in other ways.
129		156
130	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
131		158
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
134	undef $w;	161	undef $w;
135	});	162	});
136		163
137	Note that C<my $w; $w => combination. This is necessary because in Perl,	164	Note that C<my $w; $w => combination. This is necessary because in Perl,
138	my variables are only visible after the statement in which they are	165	my variables are only visible after the statement in which they are
139	declared.	166	declared.
140		167
141	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
142		169
143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
145		172
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	173	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		174	for events (AnyEvent might or might not keep a reference to this file
		175	handle). Note that only file handles pointing to things for which
		176	non-blocking operation makes sense are allowed. This includes sockets,
		177	most character devices, pipes, fifos and so on, but not for example files
		178	or block devices.
		179
147	for events. C<poll> must be a string that is either C<r> or C<w>,	180	C<poll> must be a string that is either C<r> or C<w>, which creates a
148	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
149	respectively. C<cb> is the callback to invoke each time the file handle	183	C<cb> is the callback to invoke each time the file handle becomes ready.
150	becomes ready.
151		184
152	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
153	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
154	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
155		188
…		…
159		192
160	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
161	always use non-blocking calls when reading/writing from/to your file	194	always use non-blocking calls when reading/writing from/to your file
162	handles.	195	handles.
163		196
164	Example:
165
166	# wait for readability of STDIN, then read a line and disable the watcher	197	Example: wait for readability of STDIN, then read a line and disable the
		198	watcher.
		199
167	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
168	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
169	warn "read: $input\n";	202	warn "read: $input\n";
170	undef $w;	203	undef $w;
171	});	204	});
…		…
181		214
182	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
183	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
184	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
185		218
186	The timer callback will be invoked at most once: if you want a repeating	219	The callback will normally be invoked once only. If you specify another
187	timer you have to create a new watcher (this is a limitation by both Tk	220	parameter, C<interval>, as a strictly positive number (> 0), then the
188	and Glib).	221	callback will be invoked regularly at that interval (in fractional
		222	seconds) after the first invocation. If C<interval> is specified with a
		223	false value, then it is treated as if it were missing.
189		224
190	Example:	225	The callback will be rescheduled before invoking the callback, but no
		226	attempt is done to avoid timer drift in most backends, so the interval is
		227	only approximate.
191		228
192	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
193	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
194	warn "timeout\n";	232	warn "timeout\n";
195	});	233	});
196		234
197	# to cancel the timer:	235	# to cancel the timer:
198	undef $w;	236	undef $w;
199		237
200	Example 2:
201
202	# fire an event after 0.5 seconds, then roughly every second	238	Example 2: fire an event after 0.5 seconds, then roughly every second.
203	my $w;
204		239
205	my $cb = sub {
206	# cancel the old timer while creating a new one
207	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
208	};	242	};
209
210	# start the "loop" by creating the first watcher
211	$w = AnyEvent->timer (after => 0.5, cb => $cb);
212		243
213	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
214		245
215	There are two ways to handle timers: based on real time (relative, "fire	246	There are two ways to handle timers: based on real time (relative, "fire
216	in 10 seconds") and based on wallclock time (absolute, "fire at 12	247	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
228	timers.	259	timers.
229		260
230	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
231	AnyEvent API.	262	AnyEvent API.
232		263
		264	AnyEvent has two additional methods that return the "current time":
		265
		266	=over 4
		267
		268	=item AnyEvent->time
		269
		270	This returns the "current wallclock time" as a fractional number of
		271	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		272	return, and the result is guaranteed to be compatible with those).
		273
		274	It progresses independently of any event loop processing, i.e. each call
		275	will check the system clock, which usually gets updated frequently.
		276
		277	=item AnyEvent->now
		278
		279	This also returns the "current wallclock time", but unlike C<time>, above,
		280	this value might change only once per event loop iteration, depending on
		281	the event loop (most return the same time as C<time>, above). This is the
		282	time that AnyEvent's timers get scheduled against.
		283
		284	I<In almost all cases (in all cases if you don't care), this is the
		285	function to call when you want to know the current time.>
		286
		287	This function is also often faster then C<< AnyEvent->time >>, and
		288	thus the preferred method if you want some timestamp (for example,
		289	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		290
		291	The rest of this section is only of relevance if you try to be very exact
		292	with your timing, you can skip it without bad conscience.
		293
		294	For a practical example of when these times differ, consider L<Event::Lib>
		295	and L<EV> and the following set-up:
		296
		297	The event loop is running and has just invoked one of your callback at
		298	time=500 (assume no other callbacks delay processing). In your callback,
		299	you wait a second by executing C<sleep 1> (blocking the process for a
		300	second) and then (at time=501) you create a relative timer that fires
		301	after three seconds.
		302
		303	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		304	both return C<501>, because that is the current time, and the timer will
		305	be scheduled to fire at time=504 (C<501> + C<3>).
		306
		307	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		308	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		309	last event processing phase started. With L<EV>, your timer gets scheduled
		310	to run at time=503 (C<500> + C<3>).
		311
		312	In one sense, L<Event::Lib> is more exact, as it uses the current time
		313	regardless of any delays introduced by event processing. However, most
		314	callbacks do not expect large delays in processing, so this causes a
		315	higher drift (and a lot more system calls to get the current time).
		316
		317	In another sense, L<EV> is more exact, as your timer will be scheduled at
		318	the same time, regardless of how long event processing actually took.
		319
		320	In either case, if you care (and in most cases, you don't), then you
		321	can get whatever behaviour you want with any event loop, by taking the
		322	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		323	account.
		324
		325	=back
		326
233	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
234		328
235	You can watch for signals using a signal watcher, C<signal> is the signal	329	You can watch for signals using a signal watcher, C<signal> is the signal
236	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	330	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
237	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
238		332
239	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
242		336
243	Multiple signal occurances can be clumped together into one callback	337	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	338	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	339	that it might take a while until the signal gets handled by the process,
246	but it is guarenteed not to interrupt any other callbacks.	340	but it is guaranteed not to interrupt any other callbacks.
247		341
248	The main advantage of using these watchers is that you can share a signal	342	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	343	between multiple watchers.
250		344
251	This watcher might use C<%SIG>, so programs overwriting those signals	345	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
258	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
259		353
260	You can also watch on a child process exit and catch its exit status.	354	You can also watch on a child process exit and catch its exit status.
261		355
262	The child process is specified by the C<pid> argument (if set to C<0>, it	356	The child process is specified by the C<pid> argument (if set to C<0>, it
263	watches for any child process exit). The watcher will trigger as often	357	watches for any child process exit). The watcher will triggered only when
264	as status change for the child are received. This works by installing a	358	the child process has finished and an exit status is available, not on
265	signal handler for C<SIGCHLD>. The callback will be called with the pid	359	any trace events (stopped/continued).
266	and exit status (as returned by waitpid), so unlike other watcher types,	360
267	you I<can> rely on child watcher callback arguments.	361	The callback will be called with the pid and exit status (as returned by
		362	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		363	callback arguments.
		364
		365	This watcher type works by installing a signal handler for C<SIGCHLD>,
		366	and since it cannot be shared, nothing else should use SIGCHLD or reap
		367	random child processes (waiting for specific child processes, e.g. inside
		368	C<system>, is just fine).
268		369
269	There is a slight catch to child watchers, however: you usually start them	370	There is a slight catch to child watchers, however: you usually start them
270	I<after> the child process was created, and this means the process could	371	I<after> the child process was created, and this means the process could
271	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
272		373
…		…
278	AnyEvent program, you I<have> to create at least one watcher before you	379	AnyEvent program, you I<have> to create at least one watcher before you
279	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
280		381
281	Example: fork a process and wait for it	382	Example: fork a process and wait for it
282		383
283	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
284		385
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
288		387
289	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
290	pid => $pid,	389	pid => $pid,
291	cb => sub {	390	cb => sub {
292	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
294	$done->broadcast;	393	$done->send;
295	},	394	},
296	);	395	);
297		396
298	# do something else, then wait for process exit	397	# do something else, then wait for process exit
299	$done->wait;	398	$done->recv;
300		399
301	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
302		401
		402	If you are familiar with some event loops you will know that all of them
		403	require you to run some blocking "loop", "run" or similar function that
		404	will actively watch for new events and call your callbacks.
		405
		406	AnyEvent is different, it expects somebody else to run the event loop and
		407	will only block when necessary (usually when told by the user).
		408
		409	The instrument to do that is called a "condition variable", so called
		410	because they represent a condition that must become true.
		411
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	412	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	413	>> method, usually without arguments. The only argument pair allowed is
305		414
306	A condition variable waits for a condition - precisely that the C<<	415	C<cb>, which specifies a callback to be called when the condition variable
307	->broadcast >> method has been called.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
308		418
309	They are very useful to signal that a condition has been fulfilled, for	419	After creation, the condition variable is "false" until it becomes "true"
		420	by calling the C<send> method (or calling the condition variable as if it
		421	were a callback, read about the caveats in the description for the C<<
		422	->send >> method).
		423
		424	Condition variables are similar to callbacks, except that you can
		425	optionally wait for them. They can also be called merge points - points
		426	in time where multiple outstanding events have been processed. And yet
		427	another way to call them is transactions - each condition variable can be
		428	used to represent a transaction, which finishes at some point and delivers
		429	a result.
		430
		431	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	432	for example, if you write a module that does asynchronous http requests,
311	then a condition variable would be the ideal candidate to signal the	433	then a condition variable would be the ideal candidate to signal the
312	availability of results.	434	availability of results. The user can either act when the callback is
		435	called or can synchronously C<< ->recv >> for the results.
313		436
314	You can also use condition variables to block your main program until	437	You can also use them to simulate traditional event loops - for example,
315	an event occurs - for example, you could C<< ->wait >> in your main	438	you can block your main program until an event occurs - for example, you
316	program until the user clicks the Quit button in your app, which would C<<	439	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	440	button of your app, which would C<< ->send >> the "quit" event.
318		441
319	Note that condition variables recurse into the event loop - if you have	442	Note that condition variables recurse into the event loop - if you have
320	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	443	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
321	lose. Therefore, condition variables are good to export to your caller, but	444	lose. Therefore, condition variables are good to export to your caller, but
322	you should avoid making a blocking wait yourself, at least in callbacks,	445	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	446	as this asks for trouble.
324		447
325	This object has two methods:	448	Condition variables are represented by hash refs in perl, and the keys
		449	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		450	easy (it is often useful to build your own transaction class on top of
		451	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		452	it's C<new> method in your own C<new> method.
		453
		454	There are two "sides" to a condition variable - the "producer side" which
		455	eventually calls C<< -> send >>, and the "consumer side", which waits
		456	for the send to occur.
		457
		458	Example: wait for a timer.
		459
		460	# wait till the result is ready
		461	my $result_ready = AnyEvent->condvar;
		462
		463	# do something such as adding a timer
		464	# or socket watcher the calls $result_ready->send
		465	# when the "result" is ready.
		466	# in this case, we simply use a timer:
		467	my $w = AnyEvent->timer (
		468	after => 1,
		469	cb => sub { $result_ready->send },
		470	);
		471
		472	# this "blocks" (while handling events) till the callback
		473	# calls send
		474	$result_ready->recv;
		475
		476	Example: wait for a timer, but take advantage of the fact that
		477	condition variables are also code references.
		478
		479	my $done = AnyEvent->condvar;
		480	my $delay = AnyEvent->timer (after => 5, cb => $done);
		481	$done->recv;
		482
		483	Example: Imagine an API that returns a condvar and doesn't support
		484	callbacks. This is how you make a synchronous call, for example from
		485	the main program:
		486
		487	use AnyEvent::CouchDB;
		488
		489	...
		490
		491	my @info = $couchdb->info->recv;
		492
		493	And this is how you would just ste a callback to be called whenever the
		494	results are available:
		495
		496	$couchdb->info->cb (sub {
		497	my @info = $_[0]->recv;
		498	});
		499
		500	=head3 METHODS FOR PRODUCERS
		501
		502	These methods should only be used by the producing side, i.e. the
		503	code/module that eventually sends the signal. Note that it is also
		504	the producer side which creates the condvar in most cases, but it isn't
		505	uncommon for the consumer to create it as well.
326		506
327	=over 4	507	=over 4
328		508
		509	=item $cv->send (...)
		510
		511	Flag the condition as ready - a running C<< ->recv >> and all further
		512	calls to C<recv> will (eventually) return after this method has been
		513	called. If nobody is waiting the send will be remembered.
		514
		515	If a callback has been set on the condition variable, it is called
		516	immediately from within send.
		517
		518	Any arguments passed to the C<send> call will be returned by all
		519	future C<< ->recv >> calls.
		520
		521	Condition variables are overloaded so one can call them directly
		522	(as a code reference). Calling them directly is the same as calling
		523	C<send>. Note, however, that many C-based event loops do not handle
		524	overloading, so as tempting as it may be, passing a condition variable
		525	instead of a callback does not work. Both the pure perl and EV loops
		526	support overloading, however, as well as all functions that use perl to
		527	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		528	example).
		529
		530	=item $cv->croak ($error)
		531
		532	Similar to send, but causes all call's to C<< ->recv >> to invoke
		533	C<Carp::croak> with the given error message/object/scalar.
		534
		535	This can be used to signal any errors to the condition variable
		536	user/consumer.
		537
		538	=item $cv->begin ([group callback])
		539
329	=item $cv->wait	540	=item $cv->end
330		541
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	542	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		543
		544	These two methods can be used to combine many transactions/events into
		545	one. For example, a function that pings many hosts in parallel might want
		546	to use a condition variable for the whole process.
		547
		548	Every call to C<< ->begin >> will increment a counter, and every call to
		549	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		550	>>, the (last) callback passed to C<begin> will be executed. That callback
		551	is I<supposed> to call C<< ->send >>, but that is not required. If no
		552	callback was set, C<send> will be called without any arguments.
		553
		554	Let's clarify this with the ping example:
		555
		556	my $cv = AnyEvent->condvar;
		557
		558	my %result;
		559	$cv->begin (sub { $cv->send (\%result) });
		560
		561	for my $host (@list_of_hosts) {
		562	$cv->begin;
		563	ping_host_then_call_callback $host, sub {
		564	$result{$host} = ...;
		565	$cv->end;
		566	};
		567	}
		568
		569	$cv->end;
		570
		571	This code fragment supposedly pings a number of hosts and calls
		572	C<send> after results for all then have have been gathered - in any
		573	order. To achieve this, the code issues a call to C<begin> when it starts
		574	each ping request and calls C<end> when it has received some result for
		575	it. Since C<begin> and C<end> only maintain a counter, the order in which
		576	results arrive is not relevant.
		577
		578	There is an additional bracketing call to C<begin> and C<end> outside the
		579	loop, which serves two important purposes: first, it sets the callback
		580	to be called once the counter reaches C<0>, and second, it ensures that
		581	C<send> is called even when C<no> hosts are being pinged (the loop
		582	doesn't execute once).
		583
		584	This is the general pattern when you "fan out" into multiple subrequests:
		585	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		586	is called at least once, and then, for each subrequest you start, call
		587	C<begin> and for each subrequest you finish, call C<end>.
		588
		589	=back
		590
		591	=head3 METHODS FOR CONSUMERS
		592
		593	These methods should only be used by the consuming side, i.e. the
		594	code awaits the condition.
		595
		596	=over 4
		597
		598	=item $cv->recv
		599
		600	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	601	>> methods have been called on c<$cv>, while servicing other watchers
		602	normally.
333		603
334	You can only wait once on a condition - additional calls will return	604	You can only wait once on a condition - additional calls are valid but
335	immediately.	605	will return immediately.
		606
		607	If an error condition has been set by calling C<< ->croak >>, then this
		608	function will call C<croak>.
		609
		610	In list context, all parameters passed to C<send> will be returned,
		611	in scalar context only the first one will be returned.
336		612
337	Not all event models support a blocking wait - some die in that case	613	Not all event models support a blocking wait - some die in that case
338	(programs might want to do that to stay interactive), so I<if you are	614	(programs might want to do that to stay interactive), so I<if you are
339	using this from a module, never require a blocking wait>, but let the	615	using this from a module, never require a blocking wait>, but let the
340	caller decide whether the call will block or not (for example, by coupling	616	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	617	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	618	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	619	while still supporting blocking waits if the caller so desires).
344		620
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	621	Another reason I<never> to C<< ->recv >> in a module is that you cannot
346	sensibly have two C<< ->wait >>'s in parallel, as that would require	622	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	623	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	624	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		625
352	=item $cv->broadcast	626	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		627	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		628	versions and also integrates coroutines into AnyEvent, making blocking
		629	C<< ->recv >> calls perfectly safe as long as they are done from another
		630	coroutine (one that doesn't run the event loop).
353		631
354	Flag the condition as ready - a running C<< ->wait >> and all further	632	You can ensure that C<< -recv >> never blocks by setting a callback and
355	calls to C<wait> will (eventually) return after this method has been	633	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	634	time). This will work even when the event loop does not support blocking
		635	waits otherwise.
		636
		637	=item $bool = $cv->ready
		638
		639	Returns true when the condition is "true", i.e. whether C<send> or
		640	C<croak> have been called.
		641
		642	=item $cb = $cv->cb ($cb->($cv))
		643
		644	This is a mutator function that returns the callback set and optionally
		645	replaces it before doing so.
		646
		647	The callback will be called when the condition becomes "true", i.e. when
		648	C<send> or C<croak> are called, with the only argument being the condition
		649	variable itself. Calling C<recv> inside the callback or at any later time
		650	is guaranteed not to block.
357		651
358	=back	652	=back
359
360	Example:
361
362	# wait till the result is ready
363	my $result_ready = AnyEvent->condvar;
364
365	# do something such as adding a timer
366	# or socket watcher the calls $result_ready->broadcast
367	# when the "result" is ready.
368	# in this case, we simply use a timer:
369	my $w = AnyEvent->timer (
370	after => 1,
371	cb => sub { $result_ready->broadcast },
372	);
373
374	# this "blocks" (while handling events) till the watcher
375	# calls broadcast
376	$result_ready->wait;
377		653
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		655
380	=over 4	656	=over 4
381		657
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	663	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	664	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		665
390	The known classes so far are:	666	The known classes so far are:
391		667
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	668	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	669	AnyEvent::Impl::Event based on Event, second best choice.
		670	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	671	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	672	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	673	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	674	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	675	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		676
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	689	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	690	if necessary. You should only call this function right before you would
417	have created an AnyEvent watcher anyway, that is, as late as possible at	691	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	692	runtime.
419		693
		694	=item $guard = AnyEvent::post_detect { BLOCK }
		695
		696	Arranges for the code block to be executed as soon as the event model is
		697	autodetected (or immediately if this has already happened).
		698
		699	If called in scalar or list context, then it creates and returns an object
		700	that automatically removes the callback again when it is destroyed. See
		701	L<Coro::BDB> for a case where this is useful.
		702
		703	=item @AnyEvent::post_detect
		704
		705	If there are any code references in this array (you can C<push> to it
		706	before or after loading AnyEvent), then they will called directly after
		707	the event loop has been chosen.
		708
		709	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		710	if it contains a true value then the event loop has already been detected,
		711	and the array will be ignored.
		712
		713	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		714
420	=back	715	=back
421		716
422	=head1 WHAT TO DO IN A MODULE	717	=head1 WHAT TO DO IN A MODULE
423		718
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	719	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
427	Be careful when you create watchers in the module body - AnyEvent will	722	Be careful when you create watchers in the module body - AnyEvent will
428	decide which event module to use as soon as the first method is called, so	723	decide which event module to use as soon as the first method is called, so
429	by calling AnyEvent in your module body you force the user of your module	724	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	725	to load the event module first.
431		726
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	727	Never call C<< ->recv >> on a condition variable unless you I<know> that
433	the C<< ->broadcast >> method has been called on it already. This is	728	the C<< ->send >> method has been called on it already. This is
434	because it will stall the whole program, and the whole point of using	729	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	730	events is to stay interactive.
436		731
437	It is fine, however, to call C<< ->wait >> when the user of your module	732	It is fine, however, to call C<< ->recv >> when the user of your module
438	requests it (i.e. if you create a http request object ad have a method	733	requests it (i.e. if you create a http request object ad have a method
439	called C<results> that returns the results, it should call C<< ->wait >>	734	called C<results> that returns the results, it should call C<< ->recv >>
440	freely, as the user of your module knows what she is doing. always).	735	freely, as the user of your module knows what she is doing. always).
441		736
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	737	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		738
444	There will always be a single main program - the only place that should	739	There will always be a single main program - the only place that should
…		…
446		741
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	742	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
448	do anything special (it does not need to be event-based) and let AnyEvent	743	do anything special (it does not need to be event-based) and let AnyEvent
449	decide which implementation to chose if some module relies on it.	744	decide which implementation to chose if some module relies on it.
450		745
451	If the main program relies on a specific event model. For example, in	746	If the main program relies on a specific event model - for example, in
452	Gtk2 programs you have to rely on the Glib module. You should load the	747	Gtk2 programs you have to rely on the Glib module - you should load the
453	event module before loading AnyEvent or any module that uses it: generally	748	event module before loading AnyEvent or any module that uses it: generally
454	speaking, you should load it as early as possible. The reason is that	749	speaking, you should load it as early as possible. The reason is that
455	modules might create watchers when they are loaded, and AnyEvent will	750	modules might create watchers when they are loaded, and AnyEvent will
456	decide on the event model to use as soon as it creates watchers, and it	751	decide on the event model to use as soon as it creates watchers, and it
457	might chose the wrong one unless you load the correct one yourself.	752	might chose the wrong one unless you load the correct one yourself.
458		753
459	You can chose to use a rather inefficient pure-perl implementation by	754	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	756	everywhere, but letting AnyEvent chose the model is generally better.
		757
		758	=head2 MAINLOOP EMULATION
		759
		760	Sometimes (often for short test scripts, or even standalone programs who
		761	only want to use AnyEvent), you do not want to run a specific event loop.
		762
		763	In that case, you can use a condition variable like this:
		764
		765	AnyEvent->condvar->recv;
		766
		767	This has the effect of entering the event loop and looping forever.
		768
		769	Note that usually your program has some exit condition, in which case
		770	it is better to use the "traditional" approach of storing a condition
		771	variable somewhere, waiting for it, and sending it when the program should
		772	exit cleanly.
		773
		774
		775	=head1 OTHER MODULES
		776
		777	The following is a non-exhaustive list of additional modules that use
		778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		779	in the same program. Some of the modules come with AnyEvent, some are
		780	available via CPAN.
		781
		782	=over 4
		783
		784	=item L<AnyEvent::Util>
		785
		786	Contains various utility functions that replace often-used but blocking
		787	functions such as C<inet_aton> by event-/callback-based versions.
		788
		789	=item L<AnyEvent::Socket>
		790
		791	Provides various utility functions for (internet protocol) sockets,
		792	addresses and name resolution. Also functions to create non-blocking tcp
		793	connections or tcp servers, with IPv6 and SRV record support and more.
		794
		795	=item L<AnyEvent::Handle>
		796
		797	Provide read and write buffers, manages watchers for reads and writes,
		798	supports raw and formatted I/O, I/O queued and fully transparent and
		799	non-blocking SSL/TLS.
		800
		801	=item L<AnyEvent::DNS>
		802
		803	Provides rich asynchronous DNS resolver capabilities.
		804
		805	=item L<AnyEvent::HTTP>
		806
		807	A simple-to-use HTTP library that is capable of making a lot of concurrent
		808	HTTP requests.
		809
		810	=item L<AnyEvent::HTTPD>
		811
		812	Provides a simple web application server framework.
		813
		814	=item L<AnyEvent::FastPing>
		815
		816	The fastest ping in the west.
		817
		818	=item L<AnyEvent::DBI>
		819
		820	Executes L<DBI> requests asynchronously in a proxy process.
		821
		822	=item L<AnyEvent::AIO>
		823
		824	Truly asynchronous I/O, should be in the toolbox of every event
		825	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		826	together.
		827
		828	=item L<AnyEvent::BDB>
		829
		830	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		831	L<BDB> and AnyEvent together.
		832
		833	=item L<AnyEvent::GPSD>
		834
		835	A non-blocking interface to gpsd, a daemon delivering GPS information.
		836
		837	=item L<AnyEvent::IGS>
		838
		839	A non-blocking interface to the Internet Go Server protocol (used by
		840	L<App::IGS>).
		841
		842	=item L<AnyEvent::IRC>
		843
		844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		845
		846	=item L<Net::XMPP2>
		847
		848	AnyEvent based XMPP (Jabber protocol) module family.
		849
		850	=item L<Net::FCP>
		851
		852	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		853	of AnyEvent.
		854
		855	=item L<Event::ExecFlow>
		856
		857	High level API for event-based execution flow control.
		858
		859	=item L<Coro>
		860
		861	Has special support for AnyEvent via L<Coro::AnyEvent>.
		862
		863	=item L<IO::Lambda>
		864
		865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		866
		867	=back
462		868
463	=cut	869	=cut
464		870
465	package AnyEvent;	871	package AnyEvent;
466		872
467	no warnings;	873	no warnings;
468	use strict;	874	use strict qw(vars subs);
469		875
470	use Carp;	876	use Carp;
471		877
472	our $VERSION = '3.3';	878	our $VERSION = 4.35;
473	our $MODEL;	879	our $MODEL;
474		880
475	our $AUTOLOAD;	881	our $AUTOLOAD;
476	our @ISA;	882	our @ISA;
477		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		894
480	our @REGISTRY;	895	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		896
		897	{
		898	my $idx;
		899	$PROTOCOL{$_} = ++$idx
		900	for reverse split /\s*,\s*/,
		901	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		902	}
481		903
482	my @models = (	904	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
		909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
496	);	918	);
497		919
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		921
		922	our @post_detect;
		923
		924	sub post_detect(&) {
		925	my ($cb) = @_;
		926
		927	if ($MODEL) {
		928	$cb->();
		929
		930	1
		931	} else {
		932	push @post_detect, $cb;
		933
		934	defined wantarray
		935	? bless \$cb, "AnyEvent::Util::PostDetect"
		936	: ()
		937	}
		938	}
		939
		940	sub AnyEvent::Util::PostDetect::DESTROY {
		941	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		942	}
499		943
500	sub detect() {	944	sub detect() {
501	unless ($MODEL) {	945	unless ($MODEL) {
502	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
503		948
504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
505	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
506	if (eval "require $model") {	951	if (eval "require $model") {
507	$MODEL = $model;	952	$MODEL = $model;
…		…
537	last;	982	last;
538	}	983	}
539	}	984	}
540		985
541	$MODEL	986	$MODEL
542	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	988	}
544	}	989	}
545		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
546	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		996
		997	(shift @post_detect)->() while @post_detect;
548	}	998	}
549		999
550	$MODEL	1000	$MODEL
551	}	1001	}
552		1002
…		…
560		1010
561	my $class = shift;	1011	my $class = shift;
562	$class->$func (@_);	1012	$class->$func (@_);
563	}	1013	}
564		1014
		1015	# utility function to dup a filehandle. this is used by many backends
		1016	# to support binding more than one watcher per filehandle (they usually
		1017	# allow only one watcher per fd, so we dup it to get a different one).
		1018	sub _dupfh($$$$) {
		1019	my ($poll, $fh, $r, $w) = @_;
		1020
		1021	# cygwin requires the fh mode to be matching, unix doesn't
		1022	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1023	: $poll eq "w" ? ($w, ">")
		1024	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1025
		1026	open my $fh2, "$mode&" . fileno $fh
		1027	or die "cannot dup() filehandle: $!";
		1028
		1029	# we assume CLOEXEC is already set by perl in all important cases
		1030
		1031	($fh2, $rw)
		1032	}
		1033
565	package AnyEvent::Base;	1034	package AnyEvent::Base;
566		1035
		1036	# default implementation for now and time
		1037
		1038	BEGIN {
		1039	if (eval "use Time::HiRes (); time (); 1") {
		1040	*_time = \&Time::HiRes::time;
		1041	# if (eval "use POSIX (); (POSIX::times())...
		1042	} else {
		1043	*_time = sub { time }; # epic fail
		1044	}
		1045	}
		1046
		1047	sub time { _time }
		1048	sub now { _time }
		1049
567	# default implementation for ->condvar, ->wait, ->broadcast	1050	# default implementation for ->condvar
568		1051
569	sub condvar {	1052	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
571	}
572
573	sub AnyEvent::Base::CondVar::broadcast {
574	${$_[0]}++;
575	}
576
577	sub AnyEvent::Base::CondVar::wait {
578	AnyEvent->one_event while !${$_[0]};
579	}	1054	}
580		1055
581	# default implementation for ->signal	1056	# default implementation for ->signal
582		1057
583	our %SIG_CB;	1058	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1059
		1060	sub _signal_exec {
		1061	sysread $SIGPIPE_R, my $dummy, 4;
		1062
		1063	while (%SIG_EV) {
		1064	for (keys %SIG_EV) {
		1065	delete $SIG_EV{$_};
		1066	$_->() for values %{ $SIG_CB{$_} || {} };
		1067	}
		1068	}
		1069	}
584		1070
585	sub signal {	1071	sub signal {
586	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
587		1073
		1074	unless ($SIGPIPE_R) {
		1075	require Fcntl;
		1076
		1077	if (AnyEvent::WIN32) {
		1078	require AnyEvent::Util;
		1079
		1080	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1081	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1082	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1083	} else {
		1084	pipe $SIGPIPE_R, $SIGPIPE_W;
		1085	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1086	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1087	}
		1088
		1089	$SIGPIPE_R
		1090	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1091
		1092	# not strictly required, as $^F is normally 2, but let's make sure...
		1093	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1095
		1096	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1097	}
		1098
588	my $signal = uc $arg{signal}	1099	my $signal = uc $arg{signal}
589	or Carp::croak "required option 'signal' is missing";	1100	or Carp::croak "required option 'signal' is missing";
590		1101
591	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1102	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
592	$SIG{$signal} ||= sub {	1103	$SIG{$signal} ||= sub {
593	$_->() for values %{ $SIG_CB{$signal} || {} };	1104	local $!;
		1105	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1106	undef $SIG_EV{$signal};
594	};	1107	};
595		1108
596	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1109	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
597	}	1110	}
598		1111
599	sub AnyEvent::Base::Signal::DESTROY {	1112	sub AnyEvent::Base::Signal::DESTROY {
600	my ($signal, $cb) = @{$_[0]};	1113	my ($signal, $cb) = @{$_[0]};
601		1114
602	delete $SIG_CB{$signal}{$cb};	1115	delete $SIG_CB{$signal}{$cb};
603		1116
604	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1117	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
605	}	1118	}
606		1119
607	# default implementation for ->child	1120	# default implementation for ->child
608		1121
609	our %PID_CB;	1122	our %PID_CB;
…		…
636	or Carp::croak "required option 'pid' is missing";	1149	or Carp::croak "required option 'pid' is missing";
637		1150
638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1151	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
639		1152
640	unless ($WNOHANG) {	1153	unless ($WNOHANG) {
641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } || 1;	1154	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
642	}	1155	}
643		1156
644	unless ($CHLD_W) {	1157	unless ($CHLD_W) {
645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1158	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
646	# child could be a zombie already, so make at least one round	1159	# child could be a zombie already, so make at least one round
…		…
656	delete $PID_CB{$pid}{$cb};	1169	delete $PID_CB{$pid}{$cb};
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1170	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		1171
659	undef $CHLD_W unless keys %PID_CB;	1172	undef $CHLD_W unless keys %PID_CB;
660	}	1173	}
		1174
		1175	package AnyEvent::CondVar;
		1176
		1177	our @ISA = AnyEvent::CondVar::Base::;
		1178
		1179	package AnyEvent::CondVar::Base;
		1180
		1181	use overload
		1182	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1183	fallback => 1;
		1184
		1185	sub _send {
		1186	# nop
		1187	}
		1188
		1189	sub send {
		1190	my $cv = shift;
		1191	$cv->{_ae_sent} = [@_];
		1192	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1193	$cv->_send;
		1194	}
		1195
		1196	sub croak {
		1197	$_[0]{_ae_croak} = $_[1];
		1198	$_[0]->send;
		1199	}
		1200
		1201	sub ready {
		1202	$_[0]{_ae_sent}
		1203	}
		1204
		1205	sub _wait {
		1206	AnyEvent->one_event while !$_[0]{_ae_sent};
		1207	}
		1208
		1209	sub recv {
		1210	$_[0]->_wait;
		1211
		1212	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1213	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1214	}
		1215
		1216	sub cb {
		1217	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1218	$_[0]{_ae_cb}
		1219	}
		1220
		1221	sub begin {
		1222	++$_[0]{_ae_counter};
		1223	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1224	}
		1225
		1226	sub end {
		1227	return if --$_[0]{_ae_counter};
		1228	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1229	}
		1230
		1231	# undocumented/compatibility with pre-3.4
		1232	*broadcast = \&send;
		1233	*wait = \&_wait;
		1234
		1235	=head1 ERROR AND EXCEPTION HANDLING
		1236
		1237	In general, AnyEvent does not do any error handling - it relies on the
		1238	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1239	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1240	checking of all AnyEvent methods, however, which is highly useful during
		1241	development.
		1242
		1243	As for exception handling (i.e. runtime errors and exceptions thrown while
		1244	executing a callback), this is not only highly event-loop specific, but
		1245	also not in any way wrapped by this module, as this is the job of the main
		1246	program.
		1247
		1248	The pure perl event loop simply re-throws the exception (usually
		1249	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1250	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1251	so on.
		1252
		1253	=head1 ENVIRONMENT VARIABLES
		1254
		1255	The following environment variables are used by this module or its
		1256	submodules:
		1257
		1258	=over 4
		1259
		1260	=item C<PERL_ANYEVENT_VERBOSE>
		1261
		1262	By default, AnyEvent will be completely silent except in fatal
		1263	conditions. You can set this environment variable to make AnyEvent more
		1264	talkative.
		1265
		1266	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1267	conditions, such as not being able to load the event model specified by
		1268	C<PERL_ANYEVENT_MODEL>.
		1269
		1270	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1271	model it chooses.
		1272
		1273	=item C<PERL_ANYEVENT_STRICT>
		1274
		1275	AnyEvent does not do much argument checking by default, as thorough
		1276	argument checking is very costly. Setting this variable to a true value
		1277	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1278	check the arguments passed to most method calls. If it finds any problems
		1279	it will croak.
		1280
		1281	In other words, enables "strict" mode.
		1282
		1283	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1284	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1285	developing programs can be very useful, however.
		1286
		1287	=item C<PERL_ANYEVENT_MODEL>
		1288
		1289	This can be used to specify the event model to be used by AnyEvent, before
		1290	auto detection and -probing kicks in. It must be a string consisting
		1291	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1292	and the resulting module name is loaded and if the load was successful,
		1293	used as event model. If it fails to load AnyEvent will proceed with
		1294	auto detection and -probing.
		1295
		1296	This functionality might change in future versions.
		1297
		1298	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1299	could start your program like this:
		1300
		1301	PERL_ANYEVENT_MODEL=Perl perl ...
		1302
		1303	=item C<PERL_ANYEVENT_PROTOCOLS>
		1304
		1305	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1306	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1307	of auto probing).
		1308
		1309	Must be set to a comma-separated list of protocols or address families,
		1310	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1311	used, and preference will be given to protocols mentioned earlier in the
		1312	list.
		1313
		1314	This variable can effectively be used for denial-of-service attacks
		1315	against local programs (e.g. when setuid), although the impact is likely
		1316	small, as the program has to handle conenction and other failures anyways.
		1317
		1318	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1319	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1320	- only support IPv4, never try to resolve or contact IPv6
		1321	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1322	IPv6, but prefer IPv6 over IPv4.
		1323
		1324	=item C<PERL_ANYEVENT_EDNS0>
		1325
		1326	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1327	for DNS. This extension is generally useful to reduce DNS traffic, but
		1328	some (broken) firewalls drop such DNS packets, which is why it is off by
		1329	default.
		1330
		1331	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1332	EDNS0 in its DNS requests.
		1333
		1334	=item C<PERL_ANYEVENT_MAX_FORKS>
		1335
		1336	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1337	will create in parallel.
		1338
		1339	=back
661		1340
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1341	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1342
664	This is an advanced topic that you do not normally need to use AnyEvent in	1343	This is an advanced topic that you do not normally need to use AnyEvent in
665	a module. This section is only of use to event loop authors who want to	1344	a module. This section is only of use to event loop authors who want to
…		…
699		1378
700	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1379	I<rxvt-unicode> also cheats a bit by not providing blocking access to
701	condition variables: code blocking while waiting for a condition will	1380	condition variables: code blocking while waiting for a condition will
702	C<die>. This still works with most modules/usages, and blocking calls must	1381	C<die>. This still works with most modules/usages, and blocking calls must
703	not be done in an interactive application, so it makes sense.	1382	not be done in an interactive application, so it makes sense.
704
705	=head1 ENVIRONMENT VARIABLES
706
707	The following environment variables are used by this module:
708
709	=over 4
710
711	=item C<PERL_ANYEVENT_VERBOSE>
712
713	By default, AnyEvent will be completely silent except in fatal
714	conditions. You can set this environment variable to make AnyEvent more
715	talkative.
716
717	When set to C<1> or higher, causes AnyEvent to warn about unexpected
718	conditions, such as not being able to load the event model specified by
719	C<PERL_ANYEVENT_MODEL>.
720
721	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
722	model it chooses.
723
724	=item C<PERL_ANYEVENT_MODEL>
725
726	This can be used to specify the event model to be used by AnyEvent, before
727	autodetection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
729	and the resulting module name is loaded and if the load was successful,
730	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.
732
733	This functionality might change in future versions.
734
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:
737
738	PERL_ANYEVENT_MODEL=Perl perl ...
739
740	=back
741		1383
742	=head1 EXAMPLE PROGRAM	1384	=head1 EXAMPLE PROGRAM
743		1385
744	The following program uses an I/O watcher to read data from STDIN, a timer	1386	The following program uses an I/O watcher to read data from STDIN, a timer
745	to display a message once per second, and a condition variable to quit the	1387	to display a message once per second, and a condition variable to quit the
…		…
754	poll => 'r',	1396	poll => 'r',
755	cb => sub {	1397	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1398	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1399	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1400	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1401	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1402	},
761	);	1403	);
762		1404
763	my $time_watcher; # can only be used once	1405	my $time_watcher; # can only be used once
764		1406
…		…
769	});	1411	});
770	}	1412	}
771		1413
772	new_timer; # create first timer	1414	new_timer; # create first timer
773		1415
774	$cv->wait; # wait until user enters /^q/i	1416	$cv->recv; # wait until user enters /^q/i
775		1417
776	=head1 REAL-WORLD EXAMPLE	1418	=head1 REAL-WORLD EXAMPLE
777		1419
778	Consider the L<Net::FCP> module. It features (among others) the following	1420	Consider the L<Net::FCP> module. It features (among others) the following
779	API calls, which are to freenet what HTTP GET requests are to http:	1421	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1471	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1472	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1473	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1474
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1475	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
834	result and signals any possible waiters that the request ahs finished:	1476	result and signals any possible waiters that the request has finished:
835		1477
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1478	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1479
838	if (end-of-file or data complete) {	1480	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1481	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1482	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1483	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1484	}
843		1485
844	The C<result> method, finally, just waits for the finished signal (if the	1486	The C<result> method, finally, just waits for the finished signal (if the
845	request was already finished, it doesn't wait, of course, and returns the	1487	request was already finished, it doesn't wait, of course, and returns the
846	data:	1488	data:
847		1489
848	$txn->{finished}->wait;	1490	$txn->{finished}->recv;
849	return $txn->{result};	1491	return $txn->{result};
850		1492
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1493	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1494	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1495	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1496	and just throws the exception, which means connection errors and other
855	problems get reported tot he code that tries to use the result, not in a	1497	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1498	random callback.
857		1499
…		…
888		1530
889	my $quit = AnyEvent->condvar;	1531	my $quit = AnyEvent->condvar;
890		1532
891	$fcp->txn_client_get ($url)->cb (sub {	1533	$fcp->txn_client_get ($url)->cb (sub {
892	...	1534	...
893	$quit->broadcast;	1535	$quit->send;
894	});	1536	});
895		1537
896	$quit->wait;	1538	$quit->recv;
897		1539
898		1540
899	=head1 BENCHMARKS	1541	=head1 BENCHMARKS
900		1542
901	To give you an idea of the performance and overheads that AnyEvent adds	1543	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1545	of various event loops I prepared some benchmarks.
904		1546
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1547	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1548
907	Here is a benchmark of various supported event models used natively and	1549	Here is a benchmark of various supported event models used natively and
908	through anyevent. The benchmark creates a lot of timers (with a zero	1550	through AnyEvent. The benchmark creates a lot of timers (with a zero
909	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1551	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
910	which it is), lets them fire exactly once and destroys them again.	1552	which it is), lets them fire exactly once and destroys them again.
911		1553
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1554	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1555	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1572	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1573	and memory usage is not included in the figures.
932		1574
933	I<invoke> is the time, in microseconds, used to invoke a simple	1575	I<invoke> is the time, in microseconds, used to invoke a simple
934	callback. The callback simply counts down a Perl variable and after it was	1576	callback. The callback simply counts down a Perl variable and after it was
935	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1577	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1578	signal the end of this phase.
937		1579
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1580	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1581	watcher.
940		1582
941	=head3 Results	1583	=head3 Results
942		1584
943	name watchers bytes create invoke destroy comment	1585	name watchers bytes create invoke destroy comment
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1586	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
945	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1587	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
946	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1588	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
947	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1589	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
948	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1590	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
949	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1591	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
950	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1592	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
951	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1593	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
952	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1594	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
953	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1595	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
954		1596
955	=head3 Discussion	1597	=head3 Discussion
956		1598
957	The benchmark does I<not> measure scalability of the event loop very	1599	The benchmark does I<not> measure scalability of the event loop very
958	well. For example, a select-based event loop (such as the pure perl one)	1600	well. For example, a select-based event loop (such as the pure perl one)
959	can never compete with an event loop that uses epoll when the number of	1601	can never compete with an event loop that uses epoll when the number of
960	file descriptors grows high. In this benchmark, all events become ready at	1602	file descriptors grows high. In this benchmark, all events become ready at
961	the same time, so select/poll-based implementations get an unnatural speed	1603	the same time, so select/poll-based implementations get an unnatural speed
962	boost.	1604	boost.
		1605
		1606	Also, note that the number of watchers usually has a nonlinear effect on
		1607	overall speed, that is, creating twice as many watchers doesn't take twice
		1608	the time - usually it takes longer. This puts event loops tested with a
		1609	higher number of watchers at a disadvantage.
		1610
		1611	To put the range of results into perspective, consider that on the
		1612	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1613	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1614	cycles with POE.
963		1615
964	C<EV> is the sole leader regarding speed and memory use, which are both	1616	C<EV> is the sole leader regarding speed and memory use, which are both
965	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1617	maximal/minimal, respectively. Even when going through AnyEvent, it uses
966	far less memory than any other event loop and is still faster than Event	1618	far less memory than any other event loop and is still faster than Event
967	natively.	1619	natively.
…		…
990	file descriptor is dup()ed for each watcher. This shows that the dup()	1642	file descriptor is dup()ed for each watcher. This shows that the dup()
991	employed by some adaptors is not a big performance issue (it does incur a	1643	employed by some adaptors is not a big performance issue (it does incur a
992	hidden memory cost inside the kernel which is not reflected in the figures	1644	hidden memory cost inside the kernel which is not reflected in the figures
993	above).	1645	above).
994		1646
995	C<POE>, regardless of underlying event loop (whether using its pure	1647	C<POE>, regardless of underlying event loop (whether using its pure perl
996	perl select-based backend or the Event module, the POE-EV backend	1648	select-based backend or the Event module, the POE-EV backend couldn't
997	couldn't be tested because it wasn't working) shows abysmal performance	1649	be tested because it wasn't working) shows abysmal performance and
998	and memory usage: Watchers use almost 30 times as much memory as	1650	memory usage with AnyEvent: Watchers use almost 30 times as much memory
999	EV watchers, and 10 times as much memory as Event (the high memory	1651	as EV watchers, and 10 times as much memory as Event (the high memory
1000	requirements are caused by requiring a session for each watcher). Watcher	1652	requirements are caused by requiring a session for each watcher). Watcher
1001	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1653	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1654	implementation.
		1655
1002	implementation. The design of the POE adaptor class in AnyEvent can not	1656	The design of the POE adaptor class in AnyEvent can not really account
1003	really account for this, as session creation overhead is small compared	1657	for the performance issues, though, as session creation overhead is
1004	to execution of the state machine, which is coded pretty optimally within	1658	small compared to execution of the state machine, which is coded pretty
1005	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1659	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1660	using multiple sessions is not a good approach, especially regarding
		1661	memory usage, even the author of POE could not come up with a faster
		1662	design).
1006		1663
1007	=head3 Summary	1664	=head3 Summary
1008		1665
1009	=over 4	1666	=over 4
1010		1667
…		…
1021		1678
1022	=back	1679	=back
1023		1680
1024	=head2 BENCHMARKING THE LARGE SERVER CASE	1681	=head2 BENCHMARKING THE LARGE SERVER CASE
1025		1682
1026	This benchmark atcually benchmarks the event loop itself. It works by	1683	This benchmark actually benchmarks the event loop itself. It works by
1027	creating a number of "servers": each server consists of a socketpair, a	1684	creating a number of "servers": each server consists of a socket pair, a
1028	timeout watcher that gets reset on activity (but never fires), and an I/O	1685	timeout watcher that gets reset on activity (but never fires), and an I/O
1029	watcher waiting for input on one side of the socket. Each time the socket	1686	watcher waiting for input on one side of the socket. Each time the socket
1030	watcher reads a byte it will write that byte to a random other "server".	1687	watcher reads a byte it will write that byte to a random other "server".
1031		1688
1032	The effect is that there will be a lot of I/O watchers, only part of which	1689	The effect is that there will be a lot of I/O watchers, only part of which
1033	are active at any one point (so there is a constant number of active	1690	are active at any one point (so there is a constant number of active
1034	fds for each loop iterstaion, but which fds these are is random). The	1691	fds for each loop iteration, but which fds these are is random). The
1035	timeout is reset each time something is read because that reflects how	1692	timeout is reset each time something is read because that reflects how
1036	most timeouts work (and puts extra pressure on the event loops).	1693	most timeouts work (and puts extra pressure on the event loops).
1037		1694
1038	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1695	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1039	(1%) are active. This mirrors the activity of large servers with many	1696	(1%) are active. This mirrors the activity of large servers with many
1040	connections, most of which are idle at any one point in time.	1697	connections, most of which are idle at any one point in time.
1041		1698
1042	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1699	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1043	distribution.	1700	distribution.
1044		1701
1045	=head3 Explanation of the columns	1702	=head3 Explanation of the columns
1046		1703
1047	I<sockets> is the number of sockets, and twice the number of "servers" (as	1704	I<sockets> is the number of sockets, and twice the number of "servers" (as
1048	eahc server has a read and write socket end).	1705	each server has a read and write socket end).
1049		1706
1050	I<create> is the time it takes to create a socketpair (which is	1707	I<create> is the time it takes to create a socket pair (which is
1051	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1708	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1052		1709
1053	I<request>, the most important value, is the time it takes to handle a	1710	I<request>, the most important value, is the time it takes to handle a
1054	single "request", that is, reading the token from the pipe and forwarding	1711	single "request", that is, reading the token from the pipe and forwarding
1055	it to another server. This includes deleting the old timeout and creating	1712	it to another server. This includes deleting the old timeout and creating
…		…
1057		1714
1058	=head3 Results	1715	=head3 Results
1059		1716
1060	name sockets create request	1717	name sockets create request
1061	EV 20000 69.01 11.16	1718	EV 20000 69.01 11.16
1062	Perl 20000 75.28 112.76	1719	Perl 20000 73.32 35.87
1063	Event 20000 212.62 257.32	1720	Event 20000 212.62 257.32
1064	Glib 20000 651.16 1896.30	1721	Glib 20000 651.16 1896.30
1065	POE 20000 349.67 12317.24 uses POE::Loop::Event	1722	POE 20000 349.67 12317.24 uses POE::Loop::Event
1066		1723
1067	=head3 Discussion	1724	=head3 Discussion
…		…
1089		1746
1090	=head3 Summary	1747	=head3 Summary
1091		1748
1092	=over 4	1749	=over 4
1093		1750
1094	=item * The pure perl implementation performs extremely well, considering	1751	=item * The pure perl implementation performs extremely well.
1095	that it uses select.
1096		1752
1097	=item * Avoid Glib or POE in large projects where performance matters.	1753	=item * Avoid Glib or POE in large projects where performance matters.
1098		1754
1099	=back	1755	=back
1100		1756
…		…
1113		1769
1114	=head3 Results	1770	=head3 Results
1115		1771
1116	name sockets create request	1772	name sockets create request
1117	EV 16 20.00 6.54	1773	EV 16 20.00 6.54
		1774	Perl 16 25.75 12.62
1118	Event 16 81.27 35.86	1775	Event 16 81.27 35.86
1119	Glib 16 32.63 15.48	1776	Glib 16 32.63 15.48
1120	Perl 16 24.62 162.37
1121	POE 16 261.87 276.28 uses POE::Loop::Event	1777	POE 16 261.87 276.28 uses POE::Loop::Event
1122		1778
1123	=head3 Discussion	1779	=head3 Discussion
1124		1780
1125	The benchmark tries to test the performance of a typical small	1781	The benchmark tries to test the performance of a typical small
1126	server. While knowing how various event loops perform is interesting, keep	1782	server. While knowing how various event loops perform is interesting, keep
1127	in mind that their overhead in this case is usually not as important, due	1783	in mind that their overhead in this case is usually not as important, due
1128	to the small absolute number of watchers.	1784	to the small absolute number of watchers (that is, you need efficiency and
		1785	speed most when you have lots of watchers, not when you only have a few of
		1786	them).
1129		1787
1130	EV is again fastest.	1788	EV is again fastest.
1131		1789
1132	The C-based event loops Event and Glib come in second this time, as the	1790	Perl again comes second. It is noticeably faster than the C-based event
1133	overhead of running an iteration is much smaller in C than in Perl (little	1791	loops Event and Glib, although the difference is too small to really
1134	code to execute in the inner loop, and perl's function calling overhead is	1792	matter.
1135	high, and updating all the data structures is costly).
1136		1793
1137	The pure perl event loop is much slower, but still competitive.
1138
1139	POE also performs much better in this case, but is is stillf ar behind the	1794	POE also performs much better in this case, but is is still far behind the
1140	others.	1795	others.
1141		1796
1142	=head3 Summary	1797	=head3 Summary
1143		1798
1144	=over 4	1799	=over 4
…		…
1147	watchers, as the management overhead dominates.	1802	watchers, as the management overhead dominates.
1148		1803
1149	=back	1804	=back
1150		1805
1151		1806
		1807	=head1 SIGNALS
		1808
		1809	AnyEvent currently installs handlers for these signals:
		1810
		1811	=over 4
		1812
		1813	=item SIGCHLD
		1814
		1815	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1816	emulation for event loops that do not support them natively. Also, some
		1817	event loops install a similar handler.
		1818
		1819	=item SIGPIPE
		1820
		1821	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1822	when AnyEvent gets loaded.
		1823
		1824	The rationale for this is that AnyEvent users usually do not really depend
		1825	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1826	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1827	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1828	some random socket.
		1829
		1830	The rationale for installing a no-op handler as opposed to ignoring it is
		1831	that this way, the handler will be restored to defaults on exec.
		1832
		1833	Feel free to install your own handler, or reset it to defaults.
		1834
		1835	=back
		1836
		1837	=cut
		1838
		1839	$SIG{PIPE} = sub { }
		1840	unless defined $SIG{PIPE};
		1841
		1842
1152	=head1 FORK	1843	=head1 FORK
1153		1844
1154	Most event libraries are not fork-safe. The ones who are usually are	1845	Most event libraries are not fork-safe. The ones who are usually are
1155	because they are so inefficient. Only L<EV> is fully fork-aware.	1846	because they rely on inefficient but fork-safe C<select> or C<poll>
		1847	calls. Only L<EV> is fully fork-aware.
1156		1848
1157	If you have to fork, you must either do so I<before> creating your first	1849	If you have to fork, you must either do so I<before> creating your first
1158	watcher OR you must not use AnyEvent at all in the child.	1850	watcher OR you must not use AnyEvent at all in the child.
1159		1851
1160		1852
…		…
1168	specified in the variable.	1860	specified in the variable.
1169		1861
1170	You can make AnyEvent completely ignore this variable by deleting it	1862	You can make AnyEvent completely ignore this variable by deleting it
1171	before the first watcher gets created, e.g. with a C<BEGIN> block:	1863	before the first watcher gets created, e.g. with a C<BEGIN> block:
1172		1864
1173	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1865	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1174		1866
1175	use AnyEvent;	1867	use AnyEvent;
		1868
		1869	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1870	be used to probe what backend is used and gain other information (which is
		1871	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1872	$ENV{PERL_ANYEGENT_STRICT}.
		1873
		1874
		1875	=head1 BUGS
		1876
		1877	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1878	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1879	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1880	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1881	pronounced).
1176		1882
1177		1883
1178	=head1 SEE ALSO	1884	=head1 SEE ALSO
1179		1885
1180	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1886	Utility functions: L<AnyEvent::Util>.
1181	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1887
		1888	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1182	L<Event::Lib>, L<Qt>, L<POE>.	1889	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1183		1890
1184	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1891	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1185	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1892	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1186	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1893	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1187	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1894	L<AnyEvent::Impl::POE>.
1188		1895
		1896	Non-blocking file handles, sockets, TCP clients and
		1897	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1898
		1899	Asynchronous DNS: L<AnyEvent::DNS>.
		1900
		1901	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1902
1189	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1903	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1190		1904
1191		1905
1192	=head1 AUTHOR	1906	=head1 AUTHOR
1193		1907
1194	Marc Lehmann <schmorp@schmorp.de>	1908	Marc Lehmann <schmorp@schmorp.de>
1195	http://home.schmorp.de/	1909	http://home.schmorp.de/
1196		1910
1197	=cut	1911	=cut
1198		1912
1199	1	1913	1
1200		1914

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