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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.126 by root, Fri May 23 23:44:55 2008 UTC vs.
Revision 1.190 by root, Wed Nov 5 02:21:27 2008 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 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		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
113	the callback to call, the filehandle to watch, etc.	135	the callback to call, the file handle to watch, etc.
114		136
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).
…		…
126	Many watchers either are used with "recursion" (repeating timers for	148	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	149	example), or need to refer to their watcher object in other ways.
128		150
129	An any way to achieve that is this pattern:	151	An any way to achieve that is this pattern:
130		152
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	153	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	154	# you can use $w here, for example to undef it
133	undef $w;	155	undef $w;
134	});	156	});
135		157
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	158	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	159	my variables are only visible after the statement in which they are
138	declared.	160	declared.
139		161
140	=head2 I/O WATCHERS	162	=head2 I/O WATCHERS
141		163
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	165	with the following mandatory key-value pairs as arguments:
144		166
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
146	for events. C<poll> must be a string that is either C<r> or C<w>,	168	(AnyEvent might or might not keep a reference to this file handle). C<poll>
147	which creates a watcher waiting for "r"eadable or "w"ritable events,	169	must be a string that is either C<r> or C<w>, which creates a watcher
148	respectively. C<cb> is the callback to invoke each time the file handle	170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
149	becomes ready.	171	callback to invoke each time the file handle becomes ready.
150		172
151	Although the callback might get passed parameters, their value and	173	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	174	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	175	callbacks cannot use arguments passed to I/O watcher callbacks.
154		176
…		…
158		180
159	Some event loops issue spurious readyness notifications, so you should	181	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	182	always use non-blocking calls when reading/writing from/to your file
161	handles.	183	handles.
162		184
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	185	Example: wait for readability of STDIN, then read a line and disable the
		186	watcher.
		187
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	188	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	189	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	190	warn "read: $input\n";
169	undef $w;	191	undef $w;
170	});	192	});
…		…
180		202
181	Although the callback might get passed parameters, their value and	203	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	204	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	205	callbacks cannot use arguments passed to time watcher callbacks.
184		206
185	The timer callback will be invoked at most once: if you want a repeating	207	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	208	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	209	callback will be invoked regularly at that interval (in fractional
		210	seconds) after the first invocation. If C<interval> is specified with a
		211	false value, then it is treated as if it were missing.
188		212
189	Example:	213	The callback will be rescheduled before invoking the callback, but no
		214	attempt is done to avoid timer drift in most backends, so the interval is
		215	only approximate.
190		216
191	# fire an event after 7.7 seconds	217	Example: fire an event after 7.7 seconds.
		218
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	219	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	220	warn "timeout\n";
194	});	221	});
195		222
196	# to cancel the timer:	223	# to cancel the timer:
197	undef $w;	224	undef $w;
198		225
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	226	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		227
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	228	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		229	warn "timeout\n";
207	};	230	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		231
212	=head3 TIMING ISSUES	232	=head3 TIMING ISSUES
213		233
214	There are two ways to handle timers: based on real time (relative, "fire	234	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	235	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	247	timers.
228		248
229	AnyEvent always prefers relative timers, if available, matching the	249	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	250	AnyEvent API.
231		251
		252	AnyEvent has two additional methods that return the "current time":
		253
		254	=over 4
		255
		256	=item AnyEvent->time
		257
		258	This returns the "current wallclock time" as a fractional number of
		259	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		260	return, and the result is guaranteed to be compatible with those).
		261
		262	It progresses independently of any event loop processing, i.e. each call
		263	will check the system clock, which usually gets updated frequently.
		264
		265	=item AnyEvent->now
		266
		267	This also returns the "current wallclock time", but unlike C<time>, above,
		268	this value might change only once per event loop iteration, depending on
		269	the event loop (most return the same time as C<time>, above). This is the
		270	time that AnyEvent's timers get scheduled against.
		271
		272	I<In almost all cases (in all cases if you don't care), this is the
		273	function to call when you want to know the current time.>
		274
		275	This function is also often faster then C<< AnyEvent->time >>, and
		276	thus the preferred method if you want some timestamp (for example,
		277	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		278
		279	The rest of this section is only of relevance if you try to be very exact
		280	with your timing, you can skip it without bad conscience.
		281
		282	For a practical example of when these times differ, consider L<Event::Lib>
		283	and L<EV> and the following set-up:
		284
		285	The event loop is running and has just invoked one of your callback at
		286	time=500 (assume no other callbacks delay processing). In your callback,
		287	you wait a second by executing C<sleep 1> (blocking the process for a
		288	second) and then (at time=501) you create a relative timer that fires
		289	after three seconds.
		290
		291	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		292	both return C<501>, because that is the current time, and the timer will
		293	be scheduled to fire at time=504 (C<501> + C<3>).
		294
		295	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		296	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		297	last event processing phase started. With L<EV>, your timer gets scheduled
		298	to run at time=503 (C<500> + C<3>).
		299
		300	In one sense, L<Event::Lib> is more exact, as it uses the current time
		301	regardless of any delays introduced by event processing. However, most
		302	callbacks do not expect large delays in processing, so this causes a
		303	higher drift (and a lot more system calls to get the current time).
		304
		305	In another sense, L<EV> is more exact, as your timer will be scheduled at
		306	the same time, regardless of how long event processing actually took.
		307
		308	In either case, if you care (and in most cases, you don't), then you
		309	can get whatever behaviour you want with any event loop, by taking the
		310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		311	account.
		312
		313	=back
		314
232	=head2 SIGNAL WATCHERS	315	=head2 SIGNAL WATCHERS
233		316
234	You can watch for signals using a signal watcher, C<signal> is the signal	317	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	318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	319	callback to be invoked whenever a signal occurs.
237		320
238	Although the callback might get passed parameters, their value and	321	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	322	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	323	callbacks cannot use arguments passed to signal watcher callbacks.
241		324
242	Multiple signal occurances can be clumped together into one callback	325	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	326	invocation, and callback invocation will be synchronous. Synchronous means
244	that it might take a while until the signal gets handled by the process,	327	that it might take a while until the signal gets handled by the process,
245	but it is guarenteed not to interrupt any other callbacks.	328	but it is guaranteed not to interrupt any other callbacks.
246		329
247	The main advantage of using these watchers is that you can share a signal	330	The main advantage of using these watchers is that you can share a signal
248	between multiple watchers.	331	between multiple watchers.
249		332
250	This watcher might use C<%SIG>, so programs overwriting those signals	333	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257	=head2 CHILD PROCESS WATCHERS	340	=head2 CHILD PROCESS WATCHERS
258		341
259	You can also watch on a child process exit and catch its exit status.	342	You can also watch on a child process exit and catch its exit status.
260		343
261	The child process is specified by the C<pid> argument (if set to C<0>, it	344	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	345	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	346	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	347	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	348
266	you I<can> rely on child watcher callback arguments.	349	The callback will be called with the pid and exit status (as returned by
		350	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		351	callback arguments.
		352
		353	This watcher type works by installing a signal handler for C<SIGCHLD>,
		354	and since it cannot be shared, nothing else should use SIGCHLD or reap
		355	random child processes (waiting for specific child processes, e.g. inside
		356	C<system>, is just fine).
267		357
268	There is a slight catch to child watchers, however: you usually start them	358	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	359	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	360	have exited already (and no SIGCHLD will be sent anymore).
271		361
…		…
277	AnyEvent program, you I<have> to create at least one watcher before you	367	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>).	368	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		369
280	Example: fork a process and wait for it	370	Example: fork a process and wait for it
281		371
282	my $done = AnyEvent->condvar;	372	my $done = AnyEvent->condvar;
283		373
284	my $pid = fork or exit 5;	374	my $pid = fork or exit 5;
285		375
286	my $w = AnyEvent->child (	376	my $w = AnyEvent->child (
287	pid => $pid,	377	pid => $pid,
288	cb => sub {	378	cb => sub {
289	my ($pid, $status) = @_;	379	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	380	warn "pid $pid exited with status $status";
291	$done->send;	381	$done->send;
292	},	382	},
293	);	383	);
294		384
295	# do something else, then wait for process exit	385	# do something else, then wait for process exit
296	$done->recv;	386	$done->recv;
297		387
298	=head2 CONDITION VARIABLES	388	=head2 CONDITION VARIABLES
299		389
300	If you are familiar with some event loops you will know that all of them	390	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	391	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	397	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	398	because they represent a condition that must become true.
309		399
310	Condition variables can be created by calling the C<< AnyEvent->condvar	400	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	401	>> method, usually without arguments. The only argument pair allowed is
		402
312	C<cb>, which specifies a callback to be called when the condition variable	403	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	404	becomes true, with the condition variable as the first argument (but not
		405	the results).
314		406
315	After creation, the conditon variable is "false" until it becomes "true"	407	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method.	408	by calling the C<send> method (or calling the condition variable as if it
		409	were a callback, read about the caveats in the description for the C<<
		410	->send >> method).
317		411
318	Condition variables are similar to callbacks, except that you can	412	Condition variables are similar to callbacks, except that you can
319	optionally wait for them. They can also be called merge points - points	413	optionally wait for them. They can also be called merge points - points
320	in time where multiple outstandign events have been processed. And yet	414	in time where multiple outstanding events have been processed. And yet
321	another way to call them is transations - each condition variable can be	415	another way to call them is transactions - each condition variable can be
322	used to represent a transaction, which finishes at some point and delivers	416	used to represent a transaction, which finishes at some point and delivers
323	a result.	417	a result.
324		418
325	Condition variables are very useful to signal that something has finished,	419	Condition variables are very useful to signal that something has finished,
326	for example, if you write a module that does asynchronous http requests,	420	for example, if you write a module that does asynchronous http requests,
…		…
332	you can block your main program until an event occurs - for example, you	426	you can block your main program until an event occurs - for example, you
333	could C<< ->recv >> in your main program until the user clicks the Quit	427	could C<< ->recv >> in your main program until the user clicks the Quit
334	button of your app, which would C<< ->send >> the "quit" event.	428	button of your app, which would C<< ->send >> the "quit" event.
335		429
336	Note that condition variables recurse into the event loop - if you have	430	Note that condition variables recurse into the event loop - if you have
337	two pieces of code that call C<< ->recv >> in a round-robbin fashion, you	431	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
338	lose. Therefore, condition variables are good to export to your caller, but	432	lose. Therefore, condition variables are good to export to your caller, but
339	you should avoid making a blocking wait yourself, at least in callbacks,	433	you should avoid making a blocking wait yourself, at least in callbacks,
340	as this asks for trouble.	434	as this asks for trouble.
341		435
342	Condition variables are represented by hash refs in perl, and the keys	436	Condition variables are represented by hash refs in perl, and the keys
…		…
347		441
348	There are two "sides" to a condition variable - the "producer side" which	442	There are two "sides" to a condition variable - the "producer side" which
349	eventually calls C<< -> send >>, and the "consumer side", which waits	443	eventually calls C<< -> send >>, and the "consumer side", which waits
350	for the send to occur.	444	for the send to occur.
351		445
352	Example:	446	Example: wait for a timer.
353		447
354	# wait till the result is ready	448	# wait till the result is ready
355	my $result_ready = AnyEvent->condvar;	449	my $result_ready = AnyEvent->condvar;
356		450
357	# do something such as adding a timer	451	# do something such as adding a timer
…		…
365		459
366	# this "blocks" (while handling events) till the callback	460	# this "blocks" (while handling events) till the callback
367	# calls send	461	# calls send
368	$result_ready->recv;	462	$result_ready->recv;
369		463
		464	Example: wait for a timer, but take advantage of the fact that
		465	condition variables are also code references.
		466
		467	my $done = AnyEvent->condvar;
		468	my $delay = AnyEvent->timer (after => 5, cb => $done);
		469	$done->recv;
		470
		471	Example: Imagine an API that returns a condvar and doesn't support
		472	callbacks. This is how you make a synchronous call, for example from
		473	the main program:
		474
		475	use AnyEvent::CouchDB;
		476
		477	...
		478
		479	my @info = $couchdb->info->recv;
		480
		481	And this is how you would just ste a callback to be called whenever the
		482	results are available:
		483
		484	$couchdb->info->cb (sub {
		485	my @info = $_[0]->recv;
		486	});
		487
370	=head3 METHODS FOR PRODUCERS	488	=head3 METHODS FOR PRODUCERS
371		489
372	These methods should only be used by the producing side, i.e. the	490	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	491	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	492	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	503	If a callback has been set on the condition variable, it is called
386	immediately from within send.	504	immediately from within send.
387		505
388	Any arguments passed to the C<send> call will be returned by all	506	Any arguments passed to the C<send> call will be returned by all
389	future C<< ->recv >> calls.	507	future C<< ->recv >> calls.
		508
		509	Condition variables are overloaded so one can call them directly
		510	(as a code reference). Calling them directly is the same as calling
		511	C<send>. Note, however, that many C-based event loops do not handle
		512	overloading, so as tempting as it may be, passing a condition variable
		513	instead of a callback does not work. Both the pure perl and EV loops
		514	support overloading, however, as well as all functions that use perl to
		515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		516	example).
390		517
391	=item $cv->croak ($error)	518	=item $cv->croak ($error)
392		519
393	Similar to send, but causes all call's to C<< ->recv >> to invoke	520	Similar to send, but causes all call's to C<< ->recv >> to invoke
394	C<Carp::croak> with the given error message/object/scalar.	521	C<Carp::croak> with the given error message/object/scalar.
…		…
443	doesn't execute once).	570	doesn't execute once).
444		571
445	This is the general pattern when you "fan out" into multiple subrequests:	572	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	573	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	574	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	575	C<begin> and for each subrequest you finish, call C<end>.
449		576
450	=back	577	=back
451		578
452	=head3 METHODS FOR CONSUMERS	579	=head3 METHODS FOR CONSUMERS
453		580
…		…
475	(programs might want to do that to stay interactive), so I<if you are	602	(programs might want to do that to stay interactive), so I<if you are
476	using this from a module, never require a blocking wait>, but let the	603	using this from a module, never require a blocking wait>, but let the
477	caller decide whether the call will block or not (for example, by coupling	604	caller decide whether the call will block or not (for example, by coupling
478	condition variables with some kind of request results and supporting	605	condition variables with some kind of request results and supporting
479	callbacks so the caller knows that getting the result will not block,	606	callbacks so the caller knows that getting the result will not block,
480	while still suppporting blocking waits if the caller so desires).	607	while still supporting blocking waits if the caller so desires).
481		608
482	Another reason I<never> to C<< ->recv >> in a module is that you cannot	609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
483	sensibly have two C<< ->recv >>'s in parallel, as that would require	610	sensibly have two C<< ->recv >>'s in parallel, as that would require
484	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
485	can supply.	612	can supply.
…		…
498	=item $bool = $cv->ready	625	=item $bool = $cv->ready
499		626
500	Returns true when the condition is "true", i.e. whether C<send> or	627	Returns true when the condition is "true", i.e. whether C<send> or
501	C<croak> have been called.	628	C<croak> have been called.
502		629
503	=item $cb = $cv->cb ([new callback])	630	=item $cb = $cv->cb ($cb->($cv))
504		631
505	This is a mutator function that returns the callback set and optionally	632	This is a mutator function that returns the callback set and optionally
506	replaces it before doing so.	633	replaces it before doing so.
507		634
508	The callback will be called when the condition becomes "true", i.e. when	635	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	636	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.	637	variable itself. Calling C<recv> inside the callback or at any later time
		638	is guaranteed not to block.
511		639
512	=back	640	=back
513		641
514	=head1 GLOBAL VARIABLES AND FUNCTIONS	642	=head1 GLOBAL VARIABLES AND FUNCTIONS
515		643
…		…
601		729
602	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	730	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	731	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.	732	decide which implementation to chose if some module relies on it.
605		733
606	If the main program relies on a specific event model. For example, in	734	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	735	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	736	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	737	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	738	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	739	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.	740	might chose the wrong one unless you load the correct one yourself.
613		741
614	You can chose to use a rather inefficient pure-perl implementation by	742	You can chose to use a pure-perl implementation by loading the
615	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	743	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
616	behaviour everywhere, but letting AnyEvent chose is generally better.	744	everywhere, but letting AnyEvent chose the model is generally better.
		745
		746	=head2 MAINLOOP EMULATION
		747
		748	Sometimes (often for short test scripts, or even standalone programs who
		749	only want to use AnyEvent), you do not want to run a specific event loop.
		750
		751	In that case, you can use a condition variable like this:
		752
		753	AnyEvent->condvar->recv;
		754
		755	This has the effect of entering the event loop and looping forever.
		756
		757	Note that usually your program has some exit condition, in which case
		758	it is better to use the "traditional" approach of storing a condition
		759	variable somewhere, waiting for it, and sending it when the program should
		760	exit cleanly.
		761
617		762
618	=head1 OTHER MODULES	763	=head1 OTHER MODULES
619		764
620	The following is a non-exhaustive list of additional modules that use	765	The following is a non-exhaustive list of additional modules that use
621	AnyEvent and can therefore be mixed easily with other AnyEvent modules	766	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
627	=item L<AnyEvent::Util>	772	=item L<AnyEvent::Util>
628		773
629	Contains various utility functions that replace often-used but blocking	774	Contains various utility functions that replace often-used but blocking
630	functions such as C<inet_aton> by event-/callback-based versions.	775	functions such as C<inet_aton> by event-/callback-based versions.
631		776
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>	777	=item L<AnyEvent::Socket>
637		778
638	Provides various utility functions for (internet protocol) sockets,	779	Provides various utility functions for (internet protocol) sockets,
639	addresses and name resolution. Also functions to create non-blocking tcp	780	addresses and name resolution. Also functions to create non-blocking tcp
640	connections or tcp servers, with IPv6 and SRV record support and more.	781	connections or tcp servers, with IPv6 and SRV record support and more.
641		782
		783	=item L<AnyEvent::Handle>
		784
		785	Provide read and write buffers, manages watchers for reads and writes,
		786	supports raw and formatted I/O, I/O queued and fully transparent and
		787	non-blocking SSL/TLS.
		788
		789	=item L<AnyEvent::DNS>
		790
		791	Provides rich asynchronous DNS resolver capabilities.
		792
		793	=item L<AnyEvent::HTTP>
		794
		795	A simple-to-use HTTP library that is capable of making a lot of concurrent
		796	HTTP requests.
		797
642	=item L<AnyEvent::HTTPD>	798	=item L<AnyEvent::HTTPD>
643		799
644	Provides a simple web application server framework.	800	Provides a simple web application server framework.
645		801
646	=item L<AnyEvent::DNS>
647
648	Provides rich asynchronous DNS resolver capabilities.
649
650	=item L<AnyEvent::FastPing>	802	=item L<AnyEvent::FastPing>
651		803
652	The fastest ping in the west.	804	The fastest ping in the west.
653		805
		806	=item L<AnyEvent::DBI>
		807
		808	Executes L<DBI> requests asynchronously in a proxy process.
		809
		810	=item L<AnyEvent::AIO>
		811
		812	Truly asynchronous I/O, should be in the toolbox of every event
		813	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		814	together.
		815
		816	=item L<AnyEvent::BDB>
		817
		818	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		819	L<BDB> and AnyEvent together.
		820
		821	=item L<AnyEvent::GPSD>
		822
		823	A non-blocking interface to gpsd, a daemon delivering GPS information.
		824
		825	=item L<AnyEvent::IGS>
		826
		827	A non-blocking interface to the Internet Go Server protocol (used by
		828	L<App::IGS>).
		829
654	=item L<Net::IRC3>	830	=item L<AnyEvent::IRC>
655		831
656	AnyEvent based IRC client module family.	832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
657		833
658	=item L<Net::XMPP2>	834	=item L<Net::XMPP2>
659		835
660	AnyEvent based XMPP (Jabber protocol) module family.	836	AnyEvent based XMPP (Jabber protocol) module family.
661		837
…		…
670		846
671	=item L<Coro>	847	=item L<Coro>
672		848
673	Has special support for AnyEvent via L<Coro::AnyEvent>.	849	Has special support for AnyEvent via L<Coro::AnyEvent>.
674		850
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>	851	=item L<IO::Lambda>
687		852
688	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
689		854
690	=back	855	=back
…		…
692	=cut	857	=cut
693		858
694	package AnyEvent;	859	package AnyEvent;
695		860
696	no warnings;	861	no warnings;
697	use strict;	862	use strict qw(vars subs);
698		863
699	use Carp;	864	use Carp;
700		865
701	our $VERSION = '3.6';	866	our $VERSION = 4.32;
702	our $MODEL;	867	our $MODEL;
703		868
704	our $AUTOLOAD;	869	our $AUTOLOAD;
705	our @ISA;	870	our @ISA;
706		871
		872	our @REGISTRY;
		873
		874	our $WIN32;
		875
		876	BEGIN {
		877	my $win32 = ! ! ($^O =~ /mswin32/i);
		878	eval "sub WIN32(){ $win32 }";
		879	}
		880
707	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
708		882
709	our @REGISTRY;	883	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
710
711	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
712		884
713	{	885	{
714	my $idx;	886	my $idx;
715	$PROTOCOL{$_} = ++$idx	887	$PROTOCOL{$_} = ++$idx
		888	for reverse split /\s,\s/,
716	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";	889	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
717	}	890	}
718		891
719	my @models = (	892	my @models = (
720	[EV:: => AnyEvent::Impl::EV::],	893	[EV:: => AnyEvent::Impl::EV::],
721	[Event:: => AnyEvent::Impl::Event::],	894	[Event:: => AnyEvent::Impl::Event::],
722	[Tk:: => AnyEvent::Impl::Tk::],
723	[Wx:: => AnyEvent::Impl::POE::],
724	[Prima:: => AnyEvent::Impl::POE::],
725	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
726	# everything below here will not be autoprobed as the pureperl backend should work everywhere	896	# everything below here will not be autoprobed
727	[Glib:: => AnyEvent::Impl::Glib::],	897	# as the pureperl backend should work everywhere
		898	# and is usually faster
		899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
728	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
729	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
730	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		904	[Wx:: => AnyEvent::Impl::POE::],
		905	[Prima:: => AnyEvent::Impl::POE::],
731	);	906	);
732		907
733	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
734		909
735	our @post_detect;	910	our @post_detect;
736		911
737	sub post_detect(&) {	912	sub post_detect(&) {
738	my ($cb) = @_;	913	my ($cb) = @_;
…		…
755	}	930	}
756		931
757	sub detect() {	932	sub detect() {
758	unless ($MODEL) {	933	unless ($MODEL) {
759	no strict 'refs';	934	no strict 'refs';
		935	local $SIG{__DIE__};
760		936
761	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
762	my $model = "AnyEvent::Impl::$1";	938	my $model = "AnyEvent::Impl::$1";
763	if (eval "require $model") {	939	if (eval "require $model") {
764	$MODEL = $model;	940	$MODEL = $model;
…		…
798	$MODEL	974	$MODEL
799	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
800	}	976	}
801	}	977	}
802		978
		979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		980
803	unshift @ISA, $MODEL;	981	unshift @ISA, $MODEL;
804	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	982
		983	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
805		984
806	(shift @post_detect)->() while @post_detect;	985	(shift @post_detect)->() while @post_detect;
807	}	986	}
808		987
809	$MODEL	988	$MODEL
…		…
819		998
820	my $class = shift;	999	my $class = shift;
821	$class->$func (@_);	1000	$class->$func (@_);
822	}	1001	}
823		1002
		1003	# utility function to dup a filehandle. this is used by many backends
		1004	# to support binding more than one watcher per filehandle (they usually
		1005	# allow only one watcher per fd, so we dup it to get a different one).
		1006	sub _dupfh($$$$) {
		1007	my ($poll, $fh, $r, $w) = @_;
		1008
		1009	require Fcntl;
		1010
		1011	# cygwin requires the fh mode to be matching, unix doesn't
		1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1013	: $poll eq "w" ? ($w, ">")
		1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1015
		1016	open my $fh2, "$mode&" . fileno $fh
		1017	or die "cannot dup() filehandle: $!";
		1018
		1019	# we assume CLOEXEC is already set by perl in all important cases
		1020
		1021	($fh2, $rw)
		1022	}
		1023
824	package AnyEvent::Base;	1024	package AnyEvent::Base;
		1025
		1026	# default implementation for now and time
		1027
		1028	BEGIN {
		1029	if (eval "use Time::HiRes (); time (); 1") {
		1030	*_time = \&Time::HiRes::time;
		1031	# if (eval "use POSIX (); (POSIX::times())...
		1032	} else {
		1033	*_time = sub { time }; # epic fail
		1034	}
		1035	}
		1036
		1037	sub time { _time }
		1038	sub now { _time }
825		1039
826	# default implementation for ->condvar	1040	# default implementation for ->condvar
827		1041
828	sub condvar {	1042	sub condvar {
829	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
…		…
850	sub AnyEvent::Base::Signal::DESTROY {	1064	sub AnyEvent::Base::Signal::DESTROY {
851	my ($signal, $cb) = @{$_[0]};	1065	my ($signal, $cb) = @{$_[0]};
852		1066
853	delete $SIG_CB{$signal}{$cb};	1067	delete $SIG_CB{$signal}{$cb};
854		1068
855	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
856	}	1070	}
857		1071
858	# default implementation for ->child	1072	# default implementation for ->child
859		1073
860	our %PID_CB;	1074	our %PID_CB;
…		…
887	or Carp::croak "required option 'pid' is missing";	1101	or Carp::croak "required option 'pid' is missing";
888		1102
889	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
890		1104
891	unless ($WNOHANG) {	1105	unless ($WNOHANG) {
892	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
893	}	1107	}
894		1108
895	unless ($CHLD_W) {	1109	unless ($CHLD_W) {
896	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
897	# child could be a zombie already, so make at least one round	1111	# child could be a zombie already, so make at least one round
…		…
914		1128
915	our @ISA = AnyEvent::CondVar::Base::;	1129	our @ISA = AnyEvent::CondVar::Base::;
916		1130
917	package AnyEvent::CondVar::Base;	1131	package AnyEvent::CondVar::Base;
918		1132
		1133	use overload
		1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1135	fallback => 1;
		1136
919	sub _send {	1137	sub _send {
920	# nop	1138	# nop
921	}	1139	}
922		1140
923	sub send {	1141	sub send {
…		…
963	}	1181	}
964		1182
965	# undocumented/compatibility with pre-3.4	1183	# undocumented/compatibility with pre-3.4
966	*broadcast = \&send;	1184	*broadcast = \&send;
967	*wait = \&_wait;	1185	*wait = \&_wait;
		1186
		1187	=head1 ERROR AND EXCEPTION HANDLING
		1188
		1189	In general, AnyEvent does not do any error handling - it relies on the
		1190	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1191	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1192	checking of all AnyEvent methods, however, which is highly useful during
		1193	development.
		1194
		1195	As for exception handling (i.e. runtime errors and exceptions thrown while
		1196	executing a callback), this is not only highly event-loop specific, but
		1197	also not in any way wrapped by this module, as this is the job of the main
		1198	program.
		1199
		1200	The pure perl event loop simply re-throws the exception (usually
		1201	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1202	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1203	so on.
		1204
		1205	=head1 ENVIRONMENT VARIABLES
		1206
		1207	The following environment variables are used by this module or its
		1208	submodules:
		1209
		1210	=over 4
		1211
		1212	=item C<PERL_ANYEVENT_VERBOSE>
		1213
		1214	By default, AnyEvent will be completely silent except in fatal
		1215	conditions. You can set this environment variable to make AnyEvent more
		1216	talkative.
		1217
		1218	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1219	conditions, such as not being able to load the event model specified by
		1220	C<PERL_ANYEVENT_MODEL>.
		1221
		1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1223	model it chooses.
		1224
		1225	=item C<PERL_ANYEVENT_STRICT>
		1226
		1227	AnyEvent does not do much argument checking by default, as thorough
		1228	argument checking is very costly. Setting this variable to a true value
		1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1230	check the arguments passed to most method calls. If it finds any problems
		1231	it will croak.
		1232
		1233	In other words, enables "strict" mode.
		1234
		1235	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1237	developing programs can be very useful, however.
		1238
		1239	=item C<PERL_ANYEVENT_MODEL>
		1240
		1241	This can be used to specify the event model to be used by AnyEvent, before
		1242	auto detection and -probing kicks in. It must be a string consisting
		1243	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1244	and the resulting module name is loaded and if the load was successful,
		1245	used as event model. If it fails to load AnyEvent will proceed with
		1246	auto detection and -probing.
		1247
		1248	This functionality might change in future versions.
		1249
		1250	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1251	could start your program like this:
		1252
		1253	PERL_ANYEVENT_MODEL=Perl perl ...
		1254
		1255	=item C<PERL_ANYEVENT_PROTOCOLS>
		1256
		1257	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1258	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1259	of auto probing).
		1260
		1261	Must be set to a comma-separated list of protocols or address families,
		1262	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1263	used, and preference will be given to protocols mentioned earlier in the
		1264	list.
		1265
		1266	This variable can effectively be used for denial-of-service attacks
		1267	against local programs (e.g. when setuid), although the impact is likely
		1268	small, as the program has to handle connection errors already-
		1269
		1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1272	- only support IPv4, never try to resolve or contact IPv6
		1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1274	IPv6, but prefer IPv6 over IPv4.
		1275
		1276	=item C<PERL_ANYEVENT_EDNS0>
		1277
		1278	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1279	for DNS. This extension is generally useful to reduce DNS traffic, but
		1280	some (broken) firewalls drop such DNS packets, which is why it is off by
		1281	default.
		1282
		1283	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1284	EDNS0 in its DNS requests.
		1285
		1286	=item C<PERL_ANYEVENT_MAX_FORKS>
		1287
		1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1289	will create in parallel.
		1290
		1291	=back
968		1292
969	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
970		1294
971	This is an advanced topic that you do not normally need to use AnyEvent in	1295	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	1296	a module. This section is only of use to event loop authors who want to
…		…
1006		1330
1007	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1331	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1008	condition variables: code blocking while waiting for a condition will	1332	condition variables: code blocking while waiting for a condition will
1009	C<die>. This still works with most modules/usages, and blocking calls must	1333	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.	1334	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	autodetection 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	autodetection 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 autoprobing).
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	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1059	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1060	- only support IPv4, never try to resolve or contact IPv6
1061	addressses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1062	IPv6, but prefer IPv6 over IPv4.
1063
1064	=back
1065		1335
1066	=head1 EXAMPLE PROGRAM	1336	=head1 EXAMPLE PROGRAM
1067		1337
1068	The following program uses an I/O watcher to read data from STDIN, a timer	1338	The following program uses an I/O watcher to read data from STDIN, a timer
1069	to display a message once per second, and a condition variable to quit the	1339	to display a message once per second, and a condition variable to quit the
…		…
1153	syswrite $txn->{fh}, $txn->{request}	1423	syswrite $txn->{fh}, $txn->{request}
1154	or die "connection or write error";	1424	or die "connection or write error";
1155	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1425	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1156		1426
1157	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1427	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1158	result and signals any possible waiters that the request ahs finished:	1428	result and signals any possible waiters that the request has finished:
1159		1429
1160	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1430	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1161		1431
1162	if (end-of-file or data complete) {	1432	if (end-of-file or data complete) {
1163	$txn->{result} = $txn->{buf};	1433	$txn->{result} = $txn->{buf};
…		…
1171		1441
1172	$txn->{finished}->recv;	1442	$txn->{finished}->recv;
1173	return $txn->{result};	1443	return $txn->{result};
1174		1444
1175	The actual code goes further and collects all errors (C<die>s, exceptions)	1445	The actual code goes further and collects all errors (C<die>s, exceptions)
1176	that occured during request processing. The C<result> method detects	1446	that occurred during request processing. The C<result> method detects
1177	whether an exception as thrown (it is stored inside the $txn object)	1447	whether an exception as thrown (it is stored inside the $txn object)
1178	and just throws the exception, which means connection errors and other	1448	and just throws the exception, which means connection errors and other
1179	problems get reported tot he code that tries to use the result, not in a	1449	problems get reported tot he code that tries to use the result, not in a
1180	random callback.	1450	random callback.
1181		1451
…		…
1227	of various event loops I prepared some benchmarks.	1497	of various event loops I prepared some benchmarks.
1228		1498
1229	=head2 BENCHMARKING ANYEVENT OVERHEAD	1499	=head2 BENCHMARKING ANYEVENT OVERHEAD
1230		1500
1231	Here is a benchmark of various supported event models used natively and	1501	Here is a benchmark of various supported event models used natively and
1232	through anyevent. The benchmark creates a lot of timers (with a zero	1502	through AnyEvent. The benchmark creates a lot of timers (with a zero
1233	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1503	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1234	which it is), lets them fire exactly once and destroys them again.	1504	which it is), lets them fire exactly once and destroys them again.
1235		1505
1236	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1506	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1237	distribution.	1507	distribution.
…		…
1263	watcher.	1533	watcher.
1264		1534
1265	=head3 Results	1535	=head3 Results
1266		1536
1267	name watchers bytes create invoke destroy comment	1537	name watchers bytes create invoke destroy comment
1268	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1538	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1269	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1539	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1270	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1540	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1271	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1541	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1272	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1542	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1273	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1543	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1274	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1544	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1275	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1545	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1276	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1546	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1277	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1547	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1278		1548
1279	=head3 Discussion	1549	=head3 Discussion
1280		1550
1281	The benchmark does I<not> measure scalability of the event loop very	1551	The benchmark does I<not> measure scalability of the event loop very
1282	well. For example, a select-based event loop (such as the pure perl one)	1552	well. For example, a select-based event loop (such as the pure perl one)
…		…
1360		1630
1361	=back	1631	=back
1362		1632
1363	=head2 BENCHMARKING THE LARGE SERVER CASE	1633	=head2 BENCHMARKING THE LARGE SERVER CASE
1364		1634
1365	This benchmark atcually benchmarks the event loop itself. It works by	1635	This benchmark actually benchmarks the event loop itself. It works by
1366	creating a number of "servers": each server consists of a socketpair, a	1636	creating a number of "servers": each server consists of a socket pair, a
1367	timeout watcher that gets reset on activity (but never fires), and an I/O	1637	timeout watcher that gets reset on activity (but never fires), and an I/O
1368	watcher waiting for input on one side of the socket. Each time the socket	1638	watcher waiting for input on one side of the socket. Each time the socket
1369	watcher reads a byte it will write that byte to a random other "server".	1639	watcher reads a byte it will write that byte to a random other "server".
1370		1640
1371	The effect is that there will be a lot of I/O watchers, only part of which	1641	The effect is that there will be a lot of I/O watchers, only part of which
1372	are active at any one point (so there is a constant number of active	1642	are active at any one point (so there is a constant number of active
1373	fds for each loop iterstaion, but which fds these are is random). The	1643	fds for each loop iteration, but which fds these are is random). The
1374	timeout is reset each time something is read because that reflects how	1644	timeout is reset each time something is read because that reflects how
1375	most timeouts work (and puts extra pressure on the event loops).	1645	most timeouts work (and puts extra pressure on the event loops).
1376		1646
1377	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1647	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1378	(1%) are active. This mirrors the activity of large servers with many	1648	(1%) are active. This mirrors the activity of large servers with many
1379	connections, most of which are idle at any one point in time.	1649	connections, most of which are idle at any one point in time.
1380		1650
1381	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1651	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1382	distribution.	1652	distribution.
…		…
1384	=head3 Explanation of the columns	1654	=head3 Explanation of the columns
1385		1655
1386	I<sockets> is the number of sockets, and twice the number of "servers" (as	1656	I<sockets> is the number of sockets, and twice the number of "servers" (as
1387	each server has a read and write socket end).	1657	each server has a read and write socket end).
1388		1658
1389	I<create> is the time it takes to create a socketpair (which is	1659	I<create> is the time it takes to create a socket pair (which is
1390	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1660	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1391		1661
1392	I<request>, the most important value, is the time it takes to handle a	1662	I<request>, the most important value, is the time it takes to handle a
1393	single "request", that is, reading the token from the pipe and forwarding	1663	single "request", that is, reading the token from the pipe and forwarding
1394	it to another server. This includes deleting the old timeout and creating	1664	it to another server. This includes deleting the old timeout and creating
…		…
1467	speed most when you have lots of watchers, not when you only have a few of	1737	speed most when you have lots of watchers, not when you only have a few of
1468	them).	1738	them).
1469		1739
1470	EV is again fastest.	1740	EV is again fastest.
1471		1741
1472	Perl again comes second. It is noticably faster than the C-based event	1742	Perl again comes second. It is noticeably faster than the C-based event
1473	loops Event and Glib, although the difference is too small to really	1743	loops Event and Glib, although the difference is too small to really
1474	matter.	1744	matter.
1475		1745
1476	POE also performs much better in this case, but is is still far behind the	1746	POE also performs much better in this case, but is is still far behind the
1477	others.	1747	others.
…		…
1482		1752
1483	=item * C-based event loops perform very well with small number of	1753	=item * C-based event loops perform very well with small number of
1484	watchers, as the management overhead dominates.	1754	watchers, as the management overhead dominates.
1485		1755
1486	=back	1756	=back
		1757
		1758
		1759	=head1 SIGNALS
		1760
		1761	AnyEvent currently installs handlers for these signals:
		1762
		1763	=over 4
		1764
		1765	=item SIGCHLD
		1766
		1767	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1768	emulation for event loops that do not support them natively. Also, some
		1769	event loops install a similar handler.
		1770
		1771	=item SIGPIPE
		1772
		1773	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1774	when AnyEvent gets loaded.
		1775
		1776	The rationale for this is that AnyEvent users usually do not really depend
		1777	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1778	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1779	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1780	some random socket.
		1781
		1782	The rationale for installing a no-op handler as opposed to ignoring it is
		1783	that this way, the handler will be restored to defaults on exec.
		1784
		1785	Feel free to install your own handler, or reset it to defaults.
		1786
		1787	=back
		1788
		1789	=cut
		1790
		1791	$SIG{PIPE} = sub { }
		1792	unless defined $SIG{PIPE};
1487		1793
1488		1794
1489	=head1 FORK	1795	=head1 FORK
1490		1796
1491	Most event libraries are not fork-safe. The ones who are usually are	1797	Most event libraries are not fork-safe. The ones who are usually are
…		…
1506	specified in the variable.	1812	specified in the variable.
1507		1813
1508	You can make AnyEvent completely ignore this variable by deleting it	1814	You can make AnyEvent completely ignore this variable by deleting it
1509	before the first watcher gets created, e.g. with a C<BEGIN> block:	1815	before the first watcher gets created, e.g. with a C<BEGIN> block:
1510		1816
1511	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1817	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1512		1818
1513	use AnyEvent;	1819	use AnyEvent;
1514		1820
1515	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1821	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1516	be used to probe what backend is used and gain other information (which is	1822	be used to probe what backend is used and gain other information (which is
1517	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1823	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1824	$ENV{PERL_ANYEGENT_STRICT}.
		1825
		1826
		1827	=head1 BUGS
		1828
		1829	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1830	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1831	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1832	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1833	pronounced).
1518		1834
1519		1835
1520	=head1 SEE ALSO	1836	=head1 SEE ALSO
1521		1837
1522	Utility functions: L<AnyEvent::Util>.	1838	Utility functions: L<AnyEvent::Util>.
…		…
1539	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	1855	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1540		1856
1541		1857
1542	=head1 AUTHOR	1858	=head1 AUTHOR
1543		1859
1544	Marc Lehmann <schmorp@schmorp.de>	1860	Marc Lehmann <schmorp@schmorp.de>
1545	http://home.schmorp.de/	1861	http://home.schmorp.de/
1546		1862
1547	=cut	1863	=cut
1548		1864
1549	1	1865	1
1550		1866

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Revision 1.126 by root, Fri May 23 23:44:55 2008 UTC vs.
Revision 1.190 by root, Wed Nov 5 02:21:27 2008 UTC