[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.130 by root, Sat May 24 17:21:50 2008 UTC vs.
Revision 1.200 by root, Wed Apr 1 14:02:27 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, 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	});
14		12
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	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) = @_;
16	...	23	...
17	});	24	});
18		25
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	27	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	28	$w->recv; # enters "main loop" till $condvar gets ->send
		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 enormous 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		92
71	=head1 DESCRIPTION	93	=head1 DESCRIPTION
72		94
102	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
103	use AnyEvent so their modules work together with others seamlessly...	125	use AnyEvent so their modules work together with others seamlessly...
104		126
105	The pure-perl implementation of AnyEvent is called	127	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	129	explicitly and enjoy the high availability of that event loop :)
108		130
109	=head1 WATCHERS	131	=head1 WATCHERS
110		132
111	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
112	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
…		…
115	These watchers are normal Perl objects with normal Perl lifetime. After	137	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	140	is in control).
119		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
120	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
121	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
122	to it).	150	to it).
123		151
124	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.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	154	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		156
129	An any way to achieve that is this pattern:	157	An any way to achieve that is this pattern:
130		158
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	159	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	160	# you can use $w here, for example to undef it
133	undef $w;	161	undef $w;
134	});	162	});
135		163
136	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,
137	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
138	declared.	166	declared.
139		167
140	=head2 I/O WATCHERS	168	=head2 I/O WATCHERS
141		169
142	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
143	with the following mandatory key-value pairs as arguments:	171	with the following mandatory key-value pairs as arguments:
144		172
145	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
146	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
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	181	watcher waiting for "r"eadable or "w"ritable events, respectively.
		182
148	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.
149	becomes ready.
150		184
151	Although the callback might get passed parameters, their value and	185	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	186	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	187	callbacks cannot use arguments passed to I/O watcher callbacks.
154		188
…		…
158		192
159	Some event loops issue spurious readyness notifications, so you should	193	Some event loops issue spurious readyness notifications, so you should
160	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
161	handles.	195	handles.
162		196
163	Example:
164
165	# 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
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	200	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	201	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	202	warn "read: $input\n";
169	undef $w;	203	undef $w;
170	});	204	});
…		…
180		214
181	Although the callback might get passed parameters, their value and	215	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	216	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	217	callbacks cannot use arguments passed to time watcher callbacks.
184		218
185	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
186	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
187	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.
188		224
189	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.
190		228
191	# fire an event after 7.7 seconds	229	Example: fire an event after 7.7 seconds.
		230
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	231	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	232	warn "timeout\n";
194	});	233	});
195		234
196	# to cancel the timer:	235	# to cancel the timer:
197	undef $w;	236	undef $w;
198		237
199	Example 2:
200
201	# 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.
202	my $w;
203		239
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	240	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		241	warn "timeout\n";
207	};	242	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		243
212	=head3 TIMING ISSUES	244	=head3 TIMING ISSUES
213		245
214	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
215	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
…		…
227	timers.	259	timers.
228		260
229	AnyEvent always prefers relative timers, if available, matching the	261	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	262	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	327	=head2 SIGNAL WATCHERS
233		328
234	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
235	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
236	be invoked whenever a signal occurs.	331	callback to be invoked whenever a signal occurs.
237		332
238	Although the callback might get passed parameters, their value and	333	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	334	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	335	callbacks cannot use arguments passed to signal watcher callbacks.
241		336
…		…
257	=head2 CHILD PROCESS WATCHERS	352	=head2 CHILD PROCESS WATCHERS
258		353
259	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.
260		355
261	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
262	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
263	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
264	signal handler for C<SIGCHLD>. The callback will be called with the pid	359	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	360
266	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).
267		369
268	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
269	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
270	have exited already (and no SIGCHLD will be sent anymore).	372	have exited already (and no SIGCHLD will be sent anymore).
271		373
…		…
277	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
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		381
280	Example: fork a process and wait for it	382	Example: fork a process and wait for it
281		383
282	my $done = AnyEvent->condvar;	384	my $done = AnyEvent->condvar;
283		385
284	my $pid = fork or exit 5;	386	my $pid = fork or exit 5;
285		387
286	my $w = AnyEvent->child (	388	my $w = AnyEvent->child (
287	pid => $pid,	389	pid => $pid,
288	cb => sub {	390	cb => sub {
289	my ($pid, $status) = @_;	391	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	392	warn "pid $pid exited with status $status";
291	$done->send;	393	$done->send;
292	},	394	},
293	);	395	);
294		396
295	# do something else, then wait for process exit	397	# do something else, then wait for process exit
296	$done->recv;	398	$done->recv;
297		399
298	=head2 CONDITION VARIABLES	400	=head2 CONDITION VARIABLES
299		401
300	If you are familiar with some event loops you will know that all of them	402	If you are familiar with some event loops you will know that all of them
301	require you to run some blocking "loop", "run" or similar function that	403	require you to run some blocking "loop", "run" or similar function that
…		…
307	The instrument to do that is called a "condition variable", so called	409	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	410	because they represent a condition that must become true.
309		411
310	Condition variables can be created by calling the C<< AnyEvent->condvar	412	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	413	>> method, usually without arguments. The only argument pair allowed is
		414
312	C<cb>, which specifies a callback to be called when the condition variable	415	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	416	becomes true, with the condition variable as the first argument (but not
		417	the results).
314		418
315	After creation, the condition variable is "false" until it becomes "true"	419	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method.	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).
317		423
318	Condition variables are similar to callbacks, except that you can	424	Condition variables are similar to callbacks, except that you can
319	optionally wait for them. They can also be called merge points - points	425	optionally wait for them. They can also be called merge points - points
320	in time where multiple outstanding events have been processed. And yet	426	in time where multiple outstanding events have been processed. And yet
321	another way to call them is transactions - each condition variable can be	427	another way to call them is transactions - each condition variable can be
…		…
347		453
348	There are two "sides" to a condition variable - the "producer side" which	454	There are two "sides" to a condition variable - the "producer side" which
349	eventually calls C<< -> send >>, and the "consumer side", which waits	455	eventually calls C<< -> send >>, and the "consumer side", which waits
350	for the send to occur.	456	for the send to occur.
351		457
352	Example:	458	Example: wait for a timer.
353		459
354	# wait till the result is ready	460	# wait till the result is ready
355	my $result_ready = AnyEvent->condvar;	461	my $result_ready = AnyEvent->condvar;
356		462
357	# do something such as adding a timer	463	# do something such as adding a timer
…		…
365		471
366	# this "blocks" (while handling events) till the callback	472	# this "blocks" (while handling events) till the callback
367	# calls send	473	# calls send
368	$result_ready->recv;	474	$result_ready->recv;
369		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
370	=head3 METHODS FOR PRODUCERS	500	=head3 METHODS FOR PRODUCERS
371		501
372	These methods should only be used by the producing side, i.e. the	502	These methods should only be used by the producing side, i.e. the
373	code/module that eventually sends the signal. Note that it is also	503	code/module that eventually sends the signal. Note that it is also
374	the producer side which creates the condvar in most cases, but it isn't	504	the producer side which creates the condvar in most cases, but it isn't
…		…
385	If a callback has been set on the condition variable, it is called	515	If a callback has been set on the condition variable, it is called
386	immediately from within send.	516	immediately from within send.
387		517
388	Any arguments passed to the C<send> call will be returned by all	518	Any arguments passed to the C<send> call will be returned by all
389	future C<< ->recv >> calls.	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).
390		529
391	=item $cv->croak ($error)	530	=item $cv->croak ($error)
392		531
393	Similar to send, but causes all call's to C<< ->recv >> to invoke	532	Similar to send, but causes all call's to C<< ->recv >> to invoke
394	C<Carp::croak> with the given error message/object/scalar.	533	C<Carp::croak> with the given error message/object/scalar.
…		…
498	=item $bool = $cv->ready	637	=item $bool = $cv->ready
499		638
500	Returns true when the condition is "true", i.e. whether C<send> or	639	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	640	C<croak> have been called.
502		641
503	=item $cb = $cv->cb ([new callback])	642	=item $cb = $cv->cb ($cb->($cv))
504		643
505	This is a mutator function that returns the callback set and optionally	644	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	645	replaces it before doing so.
507		646
508	The callback will be called when the condition becomes "true", i.e. when	647	The callback will be called when the condition becomes "true", i.e. when
509	C<send> or C<croak> are called. Calling C<recv> inside the callback	648	C<send> or C<croak> are called, with the only argument being the condition
510	or at any later time is guaranteed not to block.	649	variable itself. Calling C<recv> inside the callback or at any later time
		650	is guaranteed not to block.
511		651
512	=back	652	=back
513		653
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	654	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		655
…		…
601		741
602	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
603	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
604	decide which implementation to chose if some module relies on it.	744	decide which implementation to chose if some module relies on it.
605		745
606	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
607	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
608	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
609	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
610	modules might create watchers when they are loaded, and AnyEvent will	750	modules might create watchers when they are loaded, and AnyEvent will
611	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
612	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.
613		753
614	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
615	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	755	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616	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
617		774
618	=head1 OTHER MODULES	775	=head1 OTHER MODULES
619		776
620	The following is a non-exhaustive list of additional modules that use	777	The following is a non-exhaustive list of additional modules that use
621	AnyEvent and can therefore be mixed easily with other AnyEvent modules	778	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
627	=item L<AnyEvent::Util>	784	=item L<AnyEvent::Util>
628		785
629	Contains various utility functions that replace often-used but blocking	786	Contains various utility functions that replace often-used but blocking
630	functions such as C<inet_aton> by event-/callback-based versions.	787	functions such as C<inet_aton> by event-/callback-based versions.
631		788
632	=item L<AnyEvent::Handle>
633
634	Provide read and write buffers and manages watchers for reads and writes.
635
636	=item L<AnyEvent::Socket>	789	=item L<AnyEvent::Socket>
637		790
638	Provides various utility functions for (internet protocol) sockets,	791	Provides various utility functions for (internet protocol) sockets,
639	addresses and name resolution. Also functions to create non-blocking tcp	792	addresses and name resolution. Also functions to create non-blocking tcp
640	connections or tcp servers, with IPv6 and SRV record support and more.	793	connections or tcp servers, with IPv6 and SRV record support and more.
641		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
642	=item L<AnyEvent::HTTPD>	810	=item L<AnyEvent::HTTPD>
643		811
644	Provides a simple web application server framework.	812	Provides a simple web application server framework.
645		813
646	=item L<AnyEvent::DNS>
647
648	Provides rich asynchronous DNS resolver capabilities.
649
650	=item L<AnyEvent::FastPing>	814	=item L<AnyEvent::FastPing>
651		815
652	The fastest ping in the west.	816	The fastest ping in the west.
653		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
654	=item L<Net::IRC3>	842	=item L<AnyEvent::IRC>
655		843
656	AnyEvent based IRC client module family.	844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
657		845
658	=item L<Net::XMPP2>	846	=item L<Net::XMPP2>
659		847
660	AnyEvent based XMPP (Jabber protocol) module family.	848	AnyEvent based XMPP (Jabber protocol) module family.
661		849
…		…
670		858
671	=item L<Coro>	859	=item L<Coro>
672		860
673	Has special support for AnyEvent via L<Coro::AnyEvent>.	861	Has special support for AnyEvent via L<Coro::AnyEvent>.
674		862
675	=item L<AnyEvent::AIO>, L<IO::AIO>
676
677	Truly asynchronous I/O, should be in the toolbox of every event
678	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
679	together.
680
681	=item L<AnyEvent::BDB>, L<BDB>
682
683	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
684	IO::AIO and AnyEvent together.
685
686	=item L<IO::Lambda>	863	=item L<IO::Lambda>
687		864
688	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
689		866
690	=back	867	=back
…		…
692	=cut	869	=cut
693		870
694	package AnyEvent;	871	package AnyEvent;
695		872
696	no warnings;	873	no warnings;
697	use strict;	874	use strict qw(vars subs);
698		875
699	use Carp;	876	use Carp;
700		877
701	our $VERSION = '4.0';	878	our $VERSION = 4.35;
702	our $MODEL;	879	our $MODEL;
703		880
704	our $AUTOLOAD;	881	our $AUTOLOAD;
705	our @ISA;	882	our @ISA;
706		883
		884	our @REGISTRY;
		885
		886	our $WIN32;
		887
		888	BEGIN {
		889	my $win32 = ! ! ($^O =~ /mswin32/i);
		890	eval "sub WIN32(){ $win32 }";
		891	}
		892
707	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
708		894
709	our @REGISTRY;	895	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
710
711	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
712		896
713	{	897	{
714	my $idx;	898	my $idx;
715	$PROTOCOL{$_} = ++$idx	899	$PROTOCOL{$_} = ++$idx
		900	for reverse split /\s,\s/,
716	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";	901	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
717	}	902	}
718		903
719	my @models = (	904	my @models = (
720	[EV:: => AnyEvent::Impl::EV::],	905	[EV:: => AnyEvent::Impl::EV::],
721	[Event:: => AnyEvent::Impl::Event::],	906	[Event:: => AnyEvent::Impl::Event::],
722	[Tk:: => AnyEvent::Impl::Tk::],
723	[Wx:: => AnyEvent::Impl::POE::],
724	[Prima:: => AnyEvent::Impl::POE::],
725	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
726	# everything below here will not be autoprobed as the pureperl backend should work everywhere	908	# everything below here will not be autoprobed
727	[Glib:: => AnyEvent::Impl::Glib::],	909	# as the pureperl backend should work everywhere
		910	# and is usually faster
		911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
728	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
729	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
730	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		916	[Wx:: => AnyEvent::Impl::POE::],
		917	[Prima:: => AnyEvent::Impl::POE::],
731	);	918	);
732		919
733	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
734		921
735	our @post_detect;	922	our @post_detect;
736		923
737	sub post_detect(&) {	924	sub post_detect(&) {
738	my ($cb) = @_;	925	my ($cb) = @_;
…		…
755	}	942	}
756		943
757	sub detect() {	944	sub detect() {
758	unless ($MODEL) {	945	unless ($MODEL) {
759	no strict 'refs';	946	no strict 'refs';
		947	local $SIG{__DIE__};
760		948
761	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
762	my $model = "AnyEvent::Impl::$1";	950	my $model = "AnyEvent::Impl::$1";
763	if (eval "require $model") {	951	if (eval "require $model") {
764	$MODEL = $model;	952	$MODEL = $model;
…		…
798	$MODEL	986	$MODEL
799	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
800	}	988	}
801	}	989	}
802		990
		991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		992
803	unshift @ISA, $MODEL;	993	unshift @ISA, $MODEL;
804	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	994
		995	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
805		996
806	(shift @post_detect)->() while @post_detect;	997	(shift @post_detect)->() while @post_detect;
807	}	998	}
808		999
809	$MODEL	1000	$MODEL
…		…
819		1010
820	my $class = shift;	1011	my $class = shift;
821	$class->$func (@_);	1012	$class->$func (@_);
822	}	1013	}
823		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
824	package AnyEvent::Base;	1034	package AnyEvent::Base;
		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 }
825		1049
826	# default implementation for ->condvar	1050	# default implementation for ->condvar
827		1051
828	sub condvar {	1052	sub condvar {
829	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
830	}	1054	}
831		1055
832	# default implementation for ->signal	1056	# default implementation for ->signal
833		1057
834	our %SIG_CB;	1058	our ($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	}
835		1070
836	sub signal {	1071	sub signal {
837	my (undef, %arg) = @_;	1072	my (undef, %arg) = @_;
838		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	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1093	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1094
		1095	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1096	}
		1097
839	my $signal = uc $arg{signal}	1098	my $signal = uc $arg{signal}
840	or Carp::croak "required option 'signal' is missing";	1099	or Carp::croak "required option 'signal' is missing";
841		1100
842	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1101	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
843	$SIG{$signal} \|\|= sub {	1102	$SIG{$signal} \|\|= sub {
844	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1103	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1104	undef $SIG_EV{$signal};
845	};	1105	};
846		1106
847	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1107	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
848	}	1108	}
849		1109
850	sub AnyEvent::Base::Signal::DESTROY {	1110	sub AnyEvent::Base::Signal::DESTROY {
851	my ($signal, $cb) = @{$_[0]};	1111	my ($signal, $cb) = @{$_[0]};
852		1112
853	delete $SIG_CB{$signal}{$cb};	1113	delete $SIG_CB{$signal}{$cb};
854		1114
855	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1115	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
856	}	1116	}
857		1117
858	# default implementation for ->child	1118	# default implementation for ->child
859		1119
860	our %PID_CB;	1120	our %PID_CB;
…		…
887	or Carp::croak "required option 'pid' is missing";	1147	or Carp::croak "required option 'pid' is missing";
888		1148
889	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1149	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
890		1150
891	unless ($WNOHANG) {	1151	unless ($WNOHANG) {
892	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1152	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
893	}	1153	}
894		1154
895	unless ($CHLD_W) {	1155	unless ($CHLD_W) {
896	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1156	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
897	# child could be a zombie already, so make at least one round	1157	# child could be a zombie already, so make at least one round
…		…
914		1174
915	our @ISA = AnyEvent::CondVar::Base::;	1175	our @ISA = AnyEvent::CondVar::Base::;
916		1176
917	package AnyEvent::CondVar::Base;	1177	package AnyEvent::CondVar::Base;
918		1178
		1179	use overload
		1180	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1181	fallback => 1;
		1182
919	sub _send {	1183	sub _send {
920	# nop	1184	# nop
921	}	1185	}
922		1186
923	sub send {	1187	sub send {
…		…
963	}	1227	}
964		1228
965	# undocumented/compatibility with pre-3.4	1229	# undocumented/compatibility with pre-3.4
966	*broadcast = \&send;	1230	*broadcast = \&send;
967	*wait = \&_wait;	1231	*wait = \&_wait;
		1232
		1233	=head1 ERROR AND EXCEPTION HANDLING
		1234
		1235	In general, AnyEvent does not do any error handling - it relies on the
		1236	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1237	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1238	checking of all AnyEvent methods, however, which is highly useful during
		1239	development.
		1240
		1241	As for exception handling (i.e. runtime errors and exceptions thrown while
		1242	executing a callback), this is not only highly event-loop specific, but
		1243	also not in any way wrapped by this module, as this is the job of the main
		1244	program.
		1245
		1246	The pure perl event loop simply re-throws the exception (usually
		1247	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1248	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1249	so on.
		1250
		1251	=head1 ENVIRONMENT VARIABLES
		1252
		1253	The following environment variables are used by this module or its
		1254	submodules:
		1255
		1256	=over 4
		1257
		1258	=item C<PERL_ANYEVENT_VERBOSE>
		1259
		1260	By default, AnyEvent will be completely silent except in fatal
		1261	conditions. You can set this environment variable to make AnyEvent more
		1262	talkative.
		1263
		1264	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1265	conditions, such as not being able to load the event model specified by
		1266	C<PERL_ANYEVENT_MODEL>.
		1267
		1268	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1269	model it chooses.
		1270
		1271	=item C<PERL_ANYEVENT_STRICT>
		1272
		1273	AnyEvent does not do much argument checking by default, as thorough
		1274	argument checking is very costly. Setting this variable to a true value
		1275	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1276	check the arguments passed to most method calls. If it finds any problems
		1277	it will croak.
		1278
		1279	In other words, enables "strict" mode.
		1280
		1281	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1282	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1283	developing programs can be very useful, however.
		1284
		1285	=item C<PERL_ANYEVENT_MODEL>
		1286
		1287	This can be used to specify the event model to be used by AnyEvent, before
		1288	auto detection and -probing kicks in. It must be a string consisting
		1289	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1290	and the resulting module name is loaded and if the load was successful,
		1291	used as event model. If it fails to load AnyEvent will proceed with
		1292	auto detection and -probing.
		1293
		1294	This functionality might change in future versions.
		1295
		1296	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1297	could start your program like this:
		1298
		1299	PERL_ANYEVENT_MODEL=Perl perl ...
		1300
		1301	=item C<PERL_ANYEVENT_PROTOCOLS>
		1302
		1303	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1304	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1305	of auto probing).
		1306
		1307	Must be set to a comma-separated list of protocols or address families,
		1308	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1309	used, and preference will be given to protocols mentioned earlier in the
		1310	list.
		1311
		1312	This variable can effectively be used for denial-of-service attacks
		1313	against local programs (e.g. when setuid), although the impact is likely
		1314	small, as the program has to handle conenction and other failures anyways.
		1315
		1316	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1317	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1318	- only support IPv4, never try to resolve or contact IPv6
		1319	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1320	IPv6, but prefer IPv6 over IPv4.
		1321
		1322	=item C<PERL_ANYEVENT_EDNS0>
		1323
		1324	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1325	for DNS. This extension is generally useful to reduce DNS traffic, but
		1326	some (broken) firewalls drop such DNS packets, which is why it is off by
		1327	default.
		1328
		1329	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1330	EDNS0 in its DNS requests.
		1331
		1332	=item C<PERL_ANYEVENT_MAX_FORKS>
		1333
		1334	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1335	will create in parallel.
		1336
		1337	=back
968		1338
969	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1339	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
970		1340
971	This is an advanced topic that you do not normally need to use AnyEvent in	1341	This is an advanced topic that you do not normally need to use AnyEvent in
972	a module. This section is only of use to event loop authors who want to	1342	a module. This section is only of use to event loop authors who want to
…		…
1006		1376
1007	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1377	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1008	condition variables: code blocking while waiting for a condition will	1378	condition variables: code blocking while waiting for a condition will
1009	C<die>. This still works with most modules/usages, and blocking calls must	1379	C<die>. This still works with most modules/usages, and blocking calls must
1010	not be done in an interactive application, so it makes sense.	1380	not be done in an interactive application, so it makes sense.
1011
1012	=head1 ENVIRONMENT VARIABLES
1013
1014	The following environment variables are used by this module:
1015
1016	=over 4
1017
1018	=item C<PERL_ANYEVENT_VERBOSE>
1019
1020	By default, AnyEvent will be completely silent except in fatal
1021	conditions. You can set this environment variable to make AnyEvent more
1022	talkative.
1023
1024	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1025	conditions, such as not being able to load the event model specified by
1026	C<PERL_ANYEVENT_MODEL>.
1027
1028	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1029	model it chooses.
1030
1031	=item C<PERL_ANYEVENT_MODEL>
1032
1033	This can be used to specify the event model to be used by AnyEvent, before
1034	auto detection and -probing kicks in. It must be a string consisting
1035	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1036	and the resulting module name is loaded and if the load was successful,
1037	used as event model. If it fails to load AnyEvent will proceed with
1038	auto detection and -probing.
1039
1040	This functionality might change in future versions.
1041
1042	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1043	could start your program like this:
1044
1045	PERL_ANYEVENT_MODEL=Perl perl ...
1046
1047	=item C<PERL_ANYEVENT_PROTOCOLS>
1048
1049	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1050	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1051	of auto probing).
1052
1053	Must be set to a comma-separated list of protocols or address families,
1054	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1055	used, and preference will be given to protocols mentioned earlier in the
1056	list.
1057
1058	This variable can effectively be used for denial-of-service attacks
1059	against local programs (e.g. when setuid), although the impact is likely
1060	small, as the program has to handle connection errors already-
1061
1062	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1063	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1064	- only support IPv4, never try to resolve or contact IPv6
1065	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1066	IPv6, but prefer IPv6 over IPv4.
1067
1068	=item C<PERL_ANYEVENT_EDNS0>
1069
1070	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1071	for DNS. This extension is generally useful to reduce DNS traffic, but
1072	some (broken) firewalls drop such DNS packets, which is why it is off by
1073	default.
1074
1075	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1076	EDNS0 in its DNS requests.
1077
1078	=back
1079		1381
1080	=head1 EXAMPLE PROGRAM	1382	=head1 EXAMPLE PROGRAM
1081		1383
1082	The following program uses an I/O watcher to read data from STDIN, a timer	1384	The following program uses an I/O watcher to read data from STDIN, a timer
1083	to display a message once per second, and a condition variable to quit the	1385	to display a message once per second, and a condition variable to quit the
…		…
1277	watcher.	1579	watcher.
1278		1580
1279	=head3 Results	1581	=head3 Results
1280		1582
1281	name watchers bytes create invoke destroy comment	1583	name watchers bytes create invoke destroy comment
1282	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1584	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1283	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1585	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1284	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1586	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1285	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1587	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1286	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1588	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1287	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1589	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1288	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1590	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1289	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1591	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1290	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1592	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1291	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1593	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1292		1594
1293	=head3 Discussion	1595	=head3 Discussion
1294		1596
1295	The benchmark does I<not> measure scalability of the event loop very	1597	The benchmark does I<not> measure scalability of the event loop very
1296	well. For example, a select-based event loop (such as the pure perl one)	1598	well. For example, a select-based event loop (such as the pure perl one)
…		…
1498	watchers, as the management overhead dominates.	1800	watchers, as the management overhead dominates.
1499		1801
1500	=back	1802	=back
1501		1803
1502		1804
		1805	=head1 SIGNALS
		1806
		1807	AnyEvent currently installs handlers for these signals:
		1808
		1809	=over 4
		1810
		1811	=item SIGCHLD
		1812
		1813	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1814	emulation for event loops that do not support them natively. Also, some
		1815	event loops install a similar handler.
		1816
		1817	=item SIGPIPE
		1818
		1819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1820	when AnyEvent gets loaded.
		1821
		1822	The rationale for this is that AnyEvent users usually do not really depend
		1823	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1824	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1825	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1826	some random socket.
		1827
		1828	The rationale for installing a no-op handler as opposed to ignoring it is
		1829	that this way, the handler will be restored to defaults on exec.
		1830
		1831	Feel free to install your own handler, or reset it to defaults.
		1832
		1833	=back
		1834
		1835	=cut
		1836
		1837	$SIG{PIPE} = sub { }
		1838	unless defined $SIG{PIPE};
		1839
		1840
1503	=head1 FORK	1841	=head1 FORK
1504		1842
1505	Most event libraries are not fork-safe. The ones who are usually are	1843	Most event libraries are not fork-safe. The ones who are usually are
1506	because they rely on inefficient but fork-safe C<select> or C<poll>	1844	because they rely on inefficient but fork-safe C<select> or C<poll>
1507	calls. Only L<EV> is fully fork-aware.	1845	calls. Only L<EV> is fully fork-aware.
…		…
1520	specified in the variable.	1858	specified in the variable.
1521		1859
1522	You can make AnyEvent completely ignore this variable by deleting it	1860	You can make AnyEvent completely ignore this variable by deleting it
1523	before the first watcher gets created, e.g. with a C<BEGIN> block:	1861	before the first watcher gets created, e.g. with a C<BEGIN> block:
1524		1862
1525	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1863	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1526		1864
1527	use AnyEvent;	1865	use AnyEvent;
1528		1866
1529	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1867	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1530	be used to probe what backend is used and gain other information (which is	1868	be used to probe what backend is used and gain other information (which is
1531	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1869	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1870	$ENV{PERL_ANYEGENT_STRICT}.
		1871
		1872
		1873	=head1 BUGS
		1874
		1875	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1876	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1877	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1878	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1879	pronounced).
1532		1880
1533		1881
1534	=head1 SEE ALSO	1882	=head1 SEE ALSO
1535		1883
1536	Utility functions: L<AnyEvent::Util>.	1884	Utility functions: L<AnyEvent::Util>.
…		…
1553	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	1901	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1554		1902
1555		1903
1556	=head1 AUTHOR	1904	=head1 AUTHOR
1557		1905
1558	Marc Lehmann <schmorp@schmorp.de>	1906	Marc Lehmann <schmorp@schmorp.de>
1559	http://home.schmorp.de/	1907	http://home.schmorp.de/
1560		1908
1561	=cut	1909	=cut
1562		1910
1563	1	1911	1
1564		1912

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.130 by root, Sat May 24 17:21:50 2008 UTC vs. Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.130 by root, Sat May 24 17:21:50 2008 UTC vs.
Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC