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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC vs.
Revision 1.221 by root, Fri Jun 26 06:33:17 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 and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	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	55	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,	56	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,	57	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	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	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	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	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	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	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	69	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	70	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	71	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	72	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.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	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	77	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,	78	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	79	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	80	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	81	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).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	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	85	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	86	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	87	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	88	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	89	technically possible.
66		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
67	Of course, if you want lots of policy (this can arguably be somewhat	97	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	98	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	99	model, you should I<not> use this module.
70		100
71	=head1 DESCRIPTION	101	=head1 DESCRIPTION
72		102
102	starts using it, all bets are off. Maybe you should tell their authors to	132	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...	133	use AnyEvent so their modules work together with others seamlessly...
104		134
105	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
107	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
108		138
109	=head1 WATCHERS	139	=head1 WATCHERS
110		140
111	AnyEvent has the central concept of a I<watcher>, which is an object that	141	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	142	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	145	These watchers are normal Perl objects with normal Perl lifetime. After
116	creating a watcher it will immediately "watch" for events and invoke the	146	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	147	callback when the event occurs (of course, only when the event model
118	is in control).	148	is in control).
119		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
120	To disable the watcher you have to destroy it (e.g. by setting the	156	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	157	variable you store it in to C<undef> or otherwise deleting all references
122	to it).	158	to it).
123		159
124	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
126	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
127	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
128		164
129	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
130		166
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
133	undef $w;	169	undef $w;
134	});	170	});
135		171
136	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	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	173	my variables are only visible after the statement in which they are
138	declared.	174	declared.
139		175
140	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
141		177
142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
143	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
144		180
145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
146	for events. C<poll> must be a string that is either C<r> or C<w>,	188	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,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
148	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
149	becomes ready.
150		192
151	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
152	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
153	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
154		196
…		…
158		200
159	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
160	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
161	handles.	203	handles.
162		204
163	Example:
164
165	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
166	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
167	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
168	warn "read: $input\n";	210	warn "read: $input\n";
169	undef $w;	211	undef $w;
170	});	212	});
…		…
180		222
181	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
182	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
183	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
184		226
185	The timer callback will be invoked at most once: if you want a repeating	227	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	228	parameter, C<interval>, as a strictly positive number (> 0), then the
187	and Glib).	229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
188		232
189	Example:	233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
190		236
191	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
192	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
193	warn "timeout\n";	240	warn "timeout\n";
194	});	241	});
195		242
196	# to cancel the timer:	243	# to cancel the timer:
197	undef $w;	244	undef $w;
198		245
199	Example 2:
200
201	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
202	my $w;
203		247
204	my $cb = sub {
205	# cancel the old timer while creating a new one
206	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
207	};	250	};
208
209	# start the "loop" by creating the first watcher
210	$w = AnyEvent->timer (after => 0.5, cb => $cb);
211		251
212	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
213		253
214	There are two ways to handle timers: based on real time (relative, "fire	254	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	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
227	timers.	267	timers.
228		268
229	AnyEvent always prefers relative timers, if available, matching the	269	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	270	AnyEvent API.
231		271
		272	AnyEvent has two additional methods that return the "current time":
		273
		274	=over 4
		275
		276	=item AnyEvent->time
		277
		278	This returns the "current wallclock time" as a fractional number of
		279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
		281
		282	It progresses independently of any event loop processing, i.e. each call
		283	will check the system clock, which usually gets updated frequently.
		284
		285	=item AnyEvent->now
		286
		287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
		291
		292	I<In almost all cases (in all cases if you don't care), this is the
		293	function to call when you want to know the current time.>
		294
		295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
232	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
233		351
234	You can watch for signals using a signal watcher, C<signal> is the signal	352	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	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
236	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
237		355
238	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
241		359
…		…
257	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
258		376
259	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
260		378
261	The child process is specified by the C<pid> argument (if set to C<0>, it	379	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	380	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	381	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	382	any trace events (stopped/continued).
265	and exit status (as returned by waitpid), so unlike other watcher types,	383
266	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
267		392
268	There is a slight catch to child watchers, however: you usually start them	393	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	394	I<after> the child process was created, and this means the process could
270	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
271		396
272	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
273	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
274	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
275		403
276	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
277	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
279		408
280	Example: fork a process and wait for it	409	Example: fork a process and wait for it
281		410
282	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
283		412
284	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
285		414
286	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
287	pid => $pid,	416	pid => $pid,
288	cb => sub {	417	cb => sub {
289	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
290	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
291	$done->send;	420	$done->send;
292	},	421	},
293	);	422	);
294		423
295	# do something else, then wait for process exit	424	# do something else, then wait for process exit
296	$done->recv;	425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w \|\|= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
297		461
298	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
299		463
300	If you are familiar with some event loops you will know that all of them	464	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	465	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	471	The instrument to do that is called a "condition variable", so called
308	because they represent a condition that must become true.	472	because they represent a condition that must become true.
309		473
310	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
311	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
312	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
313	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
314		480
315	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
316	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
317	were a callback, read about the caveats in the description for the C<<	483	were a callback, read about the caveats in the description for the C<<
318	->send >> method).	484	->send >> method).
…		…
374		540
375	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
376	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
377	$done->recv;	543	$done->recv;
378		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
379	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
380		563
381	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
382	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
383	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
516	=item $bool = $cv->ready	699	=item $bool = $cv->ready
517		700
518	Returns true when the condition is "true", i.e. whether C<send> or	701	Returns true when the condition is "true", i.e. whether C<send> or
519	C<croak> have been called.	702	C<croak> have been called.
520		703
521	=item $cb = $cv->cb ([new callback])	704	=item $cb = $cv->cb ($cb->($cv))
522		705
523	This is a mutator function that returns the callback set and optionally	706	This is a mutator function that returns the callback set and optionally
524	replaces it before doing so.	707	replaces it before doing so.
525		708
526	The callback will be called when the condition becomes "true", i.e. when	709	The callback will be called when the condition becomes "true", i.e. when
527	C<send> or C<croak> are called. Calling C<recv> inside the callback	710	C<send> or C<croak> are called, with the only argument being the condition
528	or at any later time is guaranteed not to block.	711	variable itself. Calling C<recv> inside the callback or at any later time
		712	is guaranteed not to block.
529		713
530	=back	714	=back
531		715
532	=head1 GLOBAL VARIABLES AND FUNCTIONS	716	=head1 GLOBAL VARIABLES AND FUNCTIONS
533		717
…		…
550	AnyEvent::Impl::Tk based on Tk, very bad choice.	734	AnyEvent::Impl::Tk based on Tk, very bad choice.
551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	735	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	736	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
553	AnyEvent::Impl::POE based on POE, not generic enough for full support.	737	AnyEvent::Impl::POE based on POE, not generic enough for full support.
554		738
		739	# warning, support for IO::Async is only partial, as it is too broken
		740	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		741	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		742
555	There is no support for WxWidgets, as WxWidgets has no support for	743	There is no support for WxWidgets, as WxWidgets has no support for
556	watching file handles. However, you can use WxWidgets through the	744	watching file handles. However, you can use WxWidgets through the
557	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	745	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
558	second, which was considered to be too horrible to even consider for	746	second, which was considered to be too horrible to even consider for
559	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	747	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
662	=item L<AnyEvent::Util>	850	=item L<AnyEvent::Util>
663		851
664	Contains various utility functions that replace often-used but blocking	852	Contains various utility functions that replace often-used but blocking
665	functions such as C<inet_aton> by event-/callback-based versions.	853	functions such as C<inet_aton> by event-/callback-based versions.
666		854
667	=item L<AnyEvent::Handle>
668
669	Provide read and write buffers and manages watchers for reads and writes.
670
671	=item L<AnyEvent::Socket>	855	=item L<AnyEvent::Socket>
672		856
673	Provides various utility functions for (internet protocol) sockets,	857	Provides various utility functions for (internet protocol) sockets,
674	addresses and name resolution. Also functions to create non-blocking tcp	858	addresses and name resolution. Also functions to create non-blocking tcp
675	connections or tcp servers, with IPv6 and SRV record support and more.	859	connections or tcp servers, with IPv6 and SRV record support and more.
676		860
		861	=item L<AnyEvent::Handle>
		862
		863	Provide read and write buffers, manages watchers for reads and writes,
		864	supports raw and formatted I/O, I/O queued and fully transparent and
		865	non-blocking SSL/TLS.
		866
677	=item L<AnyEvent::DNS>	867	=item L<AnyEvent::DNS>
678		868
679	Provides rich asynchronous DNS resolver capabilities.	869	Provides rich asynchronous DNS resolver capabilities.
680		870
		871	=item L<AnyEvent::HTTP>
		872
		873	A simple-to-use HTTP library that is capable of making a lot of concurrent
		874	HTTP requests.
		875
681	=item L<AnyEvent::HTTPD>	876	=item L<AnyEvent::HTTPD>
682		877
683	Provides a simple web application server framework.	878	Provides a simple web application server framework.
684		879
685	=item L<AnyEvent::FastPing>	880	=item L<AnyEvent::FastPing>
686		881
687	The fastest ping in the west.	882	The fastest ping in the west.
688		883
		884	=item L<AnyEvent::DBI>
		885
		886	Executes L<DBI> requests asynchronously in a proxy process.
		887
		888	=item L<AnyEvent::AIO>
		889
		890	Truly asynchronous I/O, should be in the toolbox of every event
		891	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		892	together.
		893
		894	=item L<AnyEvent::BDB>
		895
		896	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		897	L<BDB> and AnyEvent together.
		898
		899	=item L<AnyEvent::GPSD>
		900
		901	A non-blocking interface to gpsd, a daemon delivering GPS information.
		902
		903	=item L<AnyEvent::IGS>
		904
		905	A non-blocking interface to the Internet Go Server protocol (used by
		906	L<App::IGS>).
		907
689	=item L<Net::IRC3>	908	=item L<AnyEvent::IRC>
690		909
691	AnyEvent based IRC client module family.	910	AnyEvent based IRC client module family (replacing the older Net::IRC3).
692		911
693	=item L<Net::XMPP2>	912	=item L<Net::XMPP2>
694		913
695	AnyEvent based XMPP (Jabber protocol) module family.	914	AnyEvent based XMPP (Jabber protocol) module family.
696		915
…		…
705		924
706	=item L<Coro>	925	=item L<Coro>
707		926
708	Has special support for AnyEvent via L<Coro::AnyEvent>.	927	Has special support for AnyEvent via L<Coro::AnyEvent>.
709		928
710	=item L<AnyEvent::AIO>, L<IO::AIO>
711
712	Truly asynchronous I/O, should be in the toolbox of every event
713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
714	together.
715
716	=item L<AnyEvent::BDB>, L<BDB>
717
718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
719	IO::AIO and AnyEvent together.
720
721	=item L<IO::Lambda>	929	=item L<IO::Lambda>
722		930
723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	931	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
724		932
725	=back	933	=back
…		…
727	=cut	935	=cut
728		936
729	package AnyEvent;	937	package AnyEvent;
730		938
731	no warnings;	939	no warnings;
732	use strict;	940	use strict qw(vars subs);
733		941
734	use Carp;	942	use Carp;
735		943
736	our $VERSION = '4.03';	944	our $VERSION = 4.42;
737	our $MODEL;	945	our $MODEL;
738		946
739	our $AUTOLOAD;	947	our $AUTOLOAD;
740	our @ISA;	948	our @ISA;
741		949
742	our @REGISTRY;	950	our @REGISTRY;
		951
		952	our $WIN32;
		953
		954	BEGIN {
		955	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		956	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		957
		958	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		959	if ${^TAINT};
		960	}
743		961
744	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	962	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
745		963
746	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	964	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
747		965
…		…
764	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	982	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
765	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	983	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
766	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	984	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
767	[Wx:: => AnyEvent::Impl::POE::],	985	[Wx:: => AnyEvent::Impl::POE::],
768	[Prima:: => AnyEvent::Impl::POE::],	986	[Prima:: => AnyEvent::Impl::POE::],
		987	# IO::Async is just too broken - we would need workaorunds for its
		988	# byzantine signal and broken child handling, among others.
		989	# IO::Async is rather hard to detect, as it doesn't have any
		990	# obvious default class.
		991	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		992	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		993	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
769	);	994	);
770		995
771	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);	996	our %method = map +($_ => 1),
		997	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
772		998
773	our @post_detect;	999	our @post_detect;
774		1000
775	sub post_detect(&) {	1001	sub post_detect(&) {
776	my ($cb) = @_;	1002	my ($cb) = @_;
…		…
781	1	1007	1
782	} else {	1008	} else {
783	push @post_detect, $cb;	1009	push @post_detect, $cb;
784		1010
785	defined wantarray	1011	defined wantarray
786	? bless \$cb, "AnyEvent::Util::PostDetect"	1012	? bless \$cb, "AnyEvent::Util::postdetect"
787	: ()	1013	: ()
788	}	1014	}
789	}	1015	}
790		1016
791	sub AnyEvent::Util::PostDetect::DESTROY {	1017	sub AnyEvent::Util::postdetect::DESTROY {
792	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1018	@post_detect = grep $_ != ${$_[0]}, @post_detect;
793	}	1019	}
794		1020
795	sub detect() {	1021	sub detect() {
796	unless ($MODEL) {	1022	unless ($MODEL) {
…		…
833	last;	1059	last;
834	}	1060	}
835	}	1061	}
836		1062
837	$MODEL	1063	$MODEL
838	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1064	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
839	}	1065	}
840	}	1066	}
841		1067
		1068	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1069
842	unshift @ISA, $MODEL;	1070	unshift @ISA, $MODEL;
843	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1071
		1072	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
844		1073
845	(shift @post_detect)->() while @post_detect;	1074	(shift @post_detect)->() while @post_detect;
846	}	1075	}
847		1076
848	$MODEL	1077	$MODEL
…		…
858		1087
859	my $class = shift;	1088	my $class = shift;
860	$class->$func (@_);	1089	$class->$func (@_);
861	}	1090	}
862		1091
		1092	# utility function to dup a filehandle. this is used by many backends
		1093	# to support binding more than one watcher per filehandle (they usually
		1094	# allow only one watcher per fd, so we dup it to get a different one).
		1095	sub _dupfh($$;$$) {
		1096	my ($poll, $fh, $r, $w) = @_;
		1097
		1098	# cygwin requires the fh mode to be matching, unix doesn't
		1099	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1100	: $poll eq "w" ? ($w, ">")
		1101	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1102
		1103	open my $fh2, "$mode&" . fileno $fh
		1104	or die "cannot dup() filehandle: $!,";
		1105
		1106	# we assume CLOEXEC is already set by perl in all important cases
		1107
		1108	($fh2, $rw)
		1109	}
		1110
863	package AnyEvent::Base;	1111	package AnyEvent::Base;
864		1112
		1113	# default implementations for many methods
		1114
		1115	BEGIN {
		1116	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1117	*_time = \&Time::HiRes::time;
		1118	# if (eval "use POSIX (); (POSIX::times())...
		1119	} else {
		1120	*_time = sub { time }; # epic fail
		1121	}
		1122	}
		1123
		1124	sub time { _time }
		1125	sub now { _time }
		1126	sub now_update { }
		1127
865	# default implementation for ->condvar	1128	# default implementation for ->condvar
866		1129
867	sub condvar {	1130	sub condvar {
868	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1131	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
869	}	1132	}
870		1133
871	# default implementation for ->signal	1134	# default implementation for ->signal
872		1135
873	our %SIG_CB;	1136	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1137
		1138	sub _signal_exec {
		1139	sysread $SIGPIPE_R, my $dummy, 4;
		1140
		1141	while (%SIG_EV) {
		1142	for (keys %SIG_EV) {
		1143	delete $SIG_EV{$_};
		1144	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1145	}
		1146	}
		1147	}
874		1148
875	sub signal {	1149	sub signal {
876	my (undef, %arg) = @_;	1150	my (undef, %arg) = @_;
877		1151
		1152	unless ($SIGPIPE_R) {
		1153	require Fcntl;
		1154
		1155	if (AnyEvent::WIN32) {
		1156	require AnyEvent::Util;
		1157
		1158	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1159	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1160	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1161	} else {
		1162	pipe $SIGPIPE_R, $SIGPIPE_W;
		1163	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1164	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1165
		1166	# not strictly required, as $^F is normally 2, but let's make sure...
		1167	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1168	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1169	}
		1170
		1171	$SIGPIPE_R
		1172	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1173
		1174	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1175	}
		1176
878	my $signal = uc $arg{signal}	1177	my $signal = uc $arg{signal}
879	or Carp::croak "required option 'signal' is missing";	1178	or Carp::croak "required option 'signal' is missing";
880		1179
881	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1180	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
882	$SIG{$signal} \|\|= sub {	1181	$SIG{$signal} \|\|= sub {
883	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1182	local $!;
		1183	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1184	undef $SIG_EV{$signal};
884	};	1185	};
885		1186
886	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1187	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
887	}	1188	}
888		1189
889	sub AnyEvent::Base::Signal::DESTROY {	1190	sub AnyEvent::Base::signal::DESTROY {
890	my ($signal, $cb) = @{$_[0]};	1191	my ($signal, $cb) = @{$_[0]};
891		1192
892	delete $SIG_CB{$signal}{$cb};	1193	delete $SIG_CB{$signal}{$cb};
893		1194
		1195	# delete doesn't work with older perls - they then
		1196	# print weird messages, or just unconditionally exit
		1197	# instead of getting the default action.
894	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1198	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
895	}	1199	}
896		1200
897	# default implementation for ->child	1201	# default implementation for ->child
898		1202
899	our %PID_CB;	1203	our %PID_CB;
900	our $CHLD_W;	1204	our $CHLD_W;
901	our $CHLD_DELAY_W;	1205	our $CHLD_DELAY_W;
902	our $PID_IDLE;
903	our $WNOHANG;	1206	our $WNOHANG;
904		1207
905	sub _child_wait {	1208	sub _sigchld {
906	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1209	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
907	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1210	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
908	(values %{ $PID_CB{0} \|\| {} });	1211	(values %{ $PID_CB{0} \|\| {} });
909	}	1212	}
910
911	undef $PID_IDLE;
912	}
913
914	sub _sigchld {
915	# make sure we deliver these changes "synchronous" with the event loop.
916	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
917	undef $CHLD_DELAY_W;
918	&_child_wait;
919	});
920	}	1213	}
921		1214
922	sub child {	1215	sub child {
923	my (undef, %arg) = @_;	1216	my (undef, %arg) = @_;
924		1217
925	defined (my $pid = $arg{pid} + 0)	1218	defined (my $pid = $arg{pid} + 0)
926	or Carp::croak "required option 'pid' is missing";	1219	or Carp::croak "required option 'pid' is missing";
927		1220
928	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1221	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
929		1222
930	unless ($WNOHANG) {
931	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1223	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
932	}
933		1224
934	unless ($CHLD_W) {	1225	unless ($CHLD_W) {
935	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1226	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
936	# child could be a zombie already, so make at least one round	1227	# child could be a zombie already, so make at least one round
937	&_sigchld;	1228	&_sigchld;
938	}	1229	}
939		1230
940	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1231	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
941	}	1232	}
942		1233
943	sub AnyEvent::Base::Child::DESTROY {	1234	sub AnyEvent::Base::child::DESTROY {
944	my ($pid, $cb) = @{$_[0]};	1235	my ($pid, $cb) = @{$_[0]};
945		1236
946	delete $PID_CB{$pid}{$cb};	1237	delete $PID_CB{$pid}{$cb};
947	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1238	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
948		1239
949	undef $CHLD_W unless keys %PID_CB;	1240	undef $CHLD_W unless keys %PID_CB;
		1241	}
		1242
		1243	# idle emulation is done by simply using a timer, regardless
		1244	# of whether the process is idle or not, and not letting
		1245	# the callback use more than 50% of the time.
		1246	sub idle {
		1247	my (undef, %arg) = @_;
		1248
		1249	my ($cb, $w, $rcb) = $arg{cb};
		1250
		1251	$rcb = sub {
		1252	if ($cb) {
		1253	$w = _time;
		1254	&$cb;
		1255	$w = _time - $w;
		1256
		1257	# never use more then 50% of the time for the idle watcher,
		1258	# within some limits
		1259	$w = 0.0001 if $w < 0.0001;
		1260	$w = 5 if $w > 5;
		1261
		1262	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1263	} else {
		1264	# clean up...
		1265	undef $w;
		1266	undef $rcb;
		1267	}
		1268	};
		1269
		1270	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1271
		1272	bless \\$cb, "AnyEvent::Base::idle"
		1273	}
		1274
		1275	sub AnyEvent::Base::idle::DESTROY {
		1276	undef $${$_[0]};
950	}	1277	}
951		1278
952	package AnyEvent::CondVar;	1279	package AnyEvent::CondVar;
953		1280
954	our @ISA = AnyEvent::CondVar::Base::;	1281	our @ISA = AnyEvent::CondVar::Base::;
…		…
1006	}	1333	}
1007		1334
1008	# undocumented/compatibility with pre-3.4	1335	# undocumented/compatibility with pre-3.4
1009	*broadcast = \&send;	1336	*broadcast = \&send;
1010	*wait = \&_wait;	1337	*wait = \&_wait;
		1338
		1339	=head1 ERROR AND EXCEPTION HANDLING
		1340
		1341	In general, AnyEvent does not do any error handling - it relies on the
		1342	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1343	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1344	checking of all AnyEvent methods, however, which is highly useful during
		1345	development.
		1346
		1347	As for exception handling (i.e. runtime errors and exceptions thrown while
		1348	executing a callback), this is not only highly event-loop specific, but
		1349	also not in any way wrapped by this module, as this is the job of the main
		1350	program.
		1351
		1352	The pure perl event loop simply re-throws the exception (usually
		1353	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1354	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1355	so on.
		1356
		1357	=head1 ENVIRONMENT VARIABLES
		1358
		1359	The following environment variables are used by this module or its
		1360	submodules.
		1361
		1362	Note that AnyEvent will remove I<all> environment variables starting with
		1363	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1364	enabled.
		1365
		1366	=over 4
		1367
		1368	=item C<PERL_ANYEVENT_VERBOSE>
		1369
		1370	By default, AnyEvent will be completely silent except in fatal
		1371	conditions. You can set this environment variable to make AnyEvent more
		1372	talkative.
		1373
		1374	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1375	conditions, such as not being able to load the event model specified by
		1376	C<PERL_ANYEVENT_MODEL>.
		1377
		1378	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1379	model it chooses.
		1380
		1381	=item C<PERL_ANYEVENT_STRICT>
		1382
		1383	AnyEvent does not do much argument checking by default, as thorough
		1384	argument checking is very costly. Setting this variable to a true value
		1385	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1386	check the arguments passed to most method calls. If it finds any problems,
		1387	it will croak.
		1388
		1389	In other words, enables "strict" mode.
		1390
		1391	Unlike C<use strict>, it is definitely recommended to keep it off in
		1392	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1393	developing programs can be very useful, however.
		1394
		1395	=item C<PERL_ANYEVENT_MODEL>
		1396
		1397	This can be used to specify the event model to be used by AnyEvent, before
		1398	auto detection and -probing kicks in. It must be a string consisting
		1399	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1400	and the resulting module name is loaded and if the load was successful,
		1401	used as event model. If it fails to load AnyEvent will proceed with
		1402	auto detection and -probing.
		1403
		1404	This functionality might change in future versions.
		1405
		1406	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1407	could start your program like this:
		1408
		1409	PERL_ANYEVENT_MODEL=Perl perl ...
		1410
		1411	=item C<PERL_ANYEVENT_PROTOCOLS>
		1412
		1413	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1414	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1415	of auto probing).
		1416
		1417	Must be set to a comma-separated list of protocols or address families,
		1418	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1419	used, and preference will be given to protocols mentioned earlier in the
		1420	list.
		1421
		1422	This variable can effectively be used for denial-of-service attacks
		1423	against local programs (e.g. when setuid), although the impact is likely
		1424	small, as the program has to handle conenction and other failures anyways.
		1425
		1426	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1427	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1428	- only support IPv4, never try to resolve or contact IPv6
		1429	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1430	IPv6, but prefer IPv6 over IPv4.
		1431
		1432	=item C<PERL_ANYEVENT_EDNS0>
		1433
		1434	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1435	for DNS. This extension is generally useful to reduce DNS traffic, but
		1436	some (broken) firewalls drop such DNS packets, which is why it is off by
		1437	default.
		1438
		1439	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1440	EDNS0 in its DNS requests.
		1441
		1442	=item C<PERL_ANYEVENT_MAX_FORKS>
		1443
		1444	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1445	will create in parallel.
		1446
		1447	=back
1011		1448
1012	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1449	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1013		1450
1014	This is an advanced topic that you do not normally need to use AnyEvent in	1451	This is an advanced topic that you do not normally need to use AnyEvent in
1015	a module. This section is only of use to event loop authors who want to	1452	a module. This section is only of use to event loop authors who want to
…		…
1049		1486
1050	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1487	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1051	condition variables: code blocking while waiting for a condition will	1488	condition variables: code blocking while waiting for a condition will
1052	C<die>. This still works with most modules/usages, and blocking calls must	1489	C<die>. This still works with most modules/usages, and blocking calls must
1053	not be done in an interactive application, so it makes sense.	1490	not be done in an interactive application, so it makes sense.
1054
1055	=head1 ENVIRONMENT VARIABLES
1056
1057	The following environment variables are used by this module:
1058
1059	=over 4
1060
1061	=item C<PERL_ANYEVENT_VERBOSE>
1062
1063	By default, AnyEvent will be completely silent except in fatal
1064	conditions. You can set this environment variable to make AnyEvent more
1065	talkative.
1066
1067	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1068	conditions, such as not being able to load the event model specified by
1069	C<PERL_ANYEVENT_MODEL>.
1070
1071	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1072	model it chooses.
1073
1074	=item C<PERL_ANYEVENT_MODEL>
1075
1076	This can be used to specify the event model to be used by AnyEvent, before
1077	auto detection and -probing kicks in. It must be a string consisting
1078	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1079	and the resulting module name is loaded and if the load was successful,
1080	used as event model. If it fails to load AnyEvent will proceed with
1081	auto detection and -probing.
1082
1083	This functionality might change in future versions.
1084
1085	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1086	could start your program like this:
1087
1088	PERL_ANYEVENT_MODEL=Perl perl ...
1089
1090	=item C<PERL_ANYEVENT_PROTOCOLS>
1091
1092	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1093	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1094	of auto probing).
1095
1096	Must be set to a comma-separated list of protocols or address families,
1097	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1098	used, and preference will be given to protocols mentioned earlier in the
1099	list.
1100
1101	This variable can effectively be used for denial-of-service attacks
1102	against local programs (e.g. when setuid), although the impact is likely
1103	small, as the program has to handle connection errors already-
1104
1105	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1106	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1107	- only support IPv4, never try to resolve or contact IPv6
1108	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1109	IPv6, but prefer IPv6 over IPv4.
1110
1111	=item C<PERL_ANYEVENT_EDNS0>
1112
1113	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1114	for DNS. This extension is generally useful to reduce DNS traffic, but
1115	some (broken) firewalls drop such DNS packets, which is why it is off by
1116	default.
1117
1118	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1119	EDNS0 in its DNS requests.
1120
1121	=back
1122		1491
1123	=head1 EXAMPLE PROGRAM	1492	=head1 EXAMPLE PROGRAM
1124		1493
1125	The following program uses an I/O watcher to read data from STDIN, a timer	1494	The following program uses an I/O watcher to read data from STDIN, a timer
1126	to display a message once per second, and a condition variable to quit the	1495	to display a message once per second, and a condition variable to quit the
…		…
1320	watcher.	1689	watcher.
1321		1690
1322	=head3 Results	1691	=head3 Results
1323		1692
1324	name watchers bytes create invoke destroy comment	1693	name watchers bytes create invoke destroy comment
1325	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1694	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1326	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1695	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1327	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1696	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1328	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1697	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1329	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1698	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1330	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1699	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1700	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1701	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1331	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1702	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1332	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1703	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1333	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1704	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1334	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1705	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1335		1706
1336	=head3 Discussion	1707	=head3 Discussion
1337		1708
1338	The benchmark does I<not> measure scalability of the event loop very	1709	The benchmark does I<not> measure scalability of the event loop very
1339	well. For example, a select-based event loop (such as the pure perl one)	1710	well. For example, a select-based event loop (such as the pure perl one)
…		…
1364	performance becomes really bad with lots of file descriptors (and few of	1735	performance becomes really bad with lots of file descriptors (and few of
1365	them active), of course, but this was not subject of this benchmark.	1736	them active), of course, but this was not subject of this benchmark.
1366		1737
1367	The C<Event> module has a relatively high setup and callback invocation	1738	The C<Event> module has a relatively high setup and callback invocation
1368	cost, but overall scores in on the third place.	1739	cost, but overall scores in on the third place.
		1740
		1741	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1742	when using its pure perl backend.
1369		1743
1370	C<Glib>'s memory usage is quite a bit higher, but it features a	1744	C<Glib>'s memory usage is quite a bit higher, but it features a
1371	faster callback invocation and overall ends up in the same class as	1745	faster callback invocation and overall ends up in the same class as
1372	C<Event>. However, Glib scales extremely badly, doubling the number of	1746	C<Event>. However, Glib scales extremely badly, doubling the number of
1373	watchers increases the processing time by more than a factor of four,	1747	watchers increases the processing time by more than a factor of four,
…		…
1451	it to another server. This includes deleting the old timeout and creating	1825	it to another server. This includes deleting the old timeout and creating
1452	a new one that moves the timeout into the future.	1826	a new one that moves the timeout into the future.
1453		1827
1454	=head3 Results	1828	=head3 Results
1455		1829
1456	name sockets create request	1830	name sockets create request
1457	EV 20000 69.01 11.16	1831	EV 20000 69.01 11.16
1458	Perl 20000 73.32 35.87	1832	Perl 20000 73.32 35.87
		1833	IOAsync 20000 157.00 98.14 epoll
		1834	IOAsync 20000 159.31 616.06 poll
1459	Event 20000 212.62 257.32	1835	Event 20000 212.62 257.32
1460	Glib 20000 651.16 1896.30	1836	Glib 20000 651.16 1896.30
1461	POE 20000 349.67 12317.24 uses POE::Loop::Event	1837	POE 20000 349.67 12317.24 uses POE::Loop::Event
1462		1838
1463	=head3 Discussion	1839	=head3 Discussion
1464		1840
1465	This benchmark I<does> measure scalability and overall performance of the	1841	This benchmark I<does> measure scalability and overall performance of the
1466	particular event loop.	1842	particular event loop.
…		…
1468	EV is again fastest. Since it is using epoll on my system, the setup time	1844	EV is again fastest. Since it is using epoll on my system, the setup time
1469	is relatively high, though.	1845	is relatively high, though.
1470		1846
1471	Perl surprisingly comes second. It is much faster than the C-based event	1847	Perl surprisingly comes second. It is much faster than the C-based event
1472	loops Event and Glib.	1848	loops Event and Glib.
		1849
		1850	IO::Async performs very well when using its epoll backend, and still quite
		1851	good compared to Glib when using its pure perl backend.
1473		1852
1474	Event suffers from high setup time as well (look at its code and you will	1853	Event suffers from high setup time as well (look at its code and you will
1475	understand why). Callback invocation also has a high overhead compared to	1854	understand why). Callback invocation also has a high overhead compared to
1476	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1855	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1477	uses select or poll in basically all documented configurations.	1856	uses select or poll in basically all documented configurations.
…		…
1540	=item * C-based event loops perform very well with small number of	1919	=item * C-based event loops perform very well with small number of
1541	watchers, as the management overhead dominates.	1920	watchers, as the management overhead dominates.
1542		1921
1543	=back	1922	=back
1544		1923
		1924	=head2 THE IO::Lambda BENCHMARK
		1925
		1926	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1927	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1928	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1929	shouldn't come as a surprise to anybody). As such, the benchmark is
		1930	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1931	very optimal. But how would AnyEvent compare when used without the extra
		1932	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1933
		1934	The benchmark itself creates an echo-server, and then, for 500 times,
		1935	connects to the echo server, sends a line, waits for the reply, and then
		1936	creates the next connection. This is a rather bad benchmark, as it doesn't
		1937	test the efficiency of the framework or much non-blocking I/O, but it is a
		1938	benchmark nevertheless.
		1939
		1940	name runtime
		1941	Lambda/select 0.330 sec
		1942	+ optimized 0.122 sec
		1943	Lambda/AnyEvent 0.327 sec
		1944	+ optimized 0.138 sec
		1945	Raw sockets/select 0.077 sec
		1946	POE/select, components 0.662 sec
		1947	POE/select, raw sockets 0.226 sec
		1948	POE/select, optimized 0.404 sec
		1949
		1950	AnyEvent/select/nb 0.085 sec
		1951	AnyEvent/EV/nb 0.068 sec
		1952	+state machine 0.134 sec
		1953
		1954	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1955	benchmarks actually make blocking connects and use 100% blocking I/O,
		1956	defeating the purpose of an event-based solution. All of the newly
		1957	written AnyEvent benchmarks use 100% non-blocking connects (using
		1958	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1959	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		1960	generally require a lot more bookkeeping and event handling than blocking
		1961	connects (which involve a single syscall only).
		1962
		1963	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1964	offers similar expressive power as POE and IO::Lambda, using conventional
		1965	Perl syntax. This means that both the echo server and the client are 100%
		1966	non-blocking, further placing it at a disadvantage.
		1967
		1968	As you can see, the AnyEvent + EV combination even beats the
		1969	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1970	backend easily beats IO::Lambda and POE.
		1971
		1972	And even the 100% non-blocking version written using the high-level (and
		1973	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		1974	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1975	in a non-blocking way.
		1976
		1977	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		1978	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		1979	part of the IO::lambda distribution and were used without any changes.
		1980
		1981
		1982	=head1 SIGNALS
		1983
		1984	AnyEvent currently installs handlers for these signals:
		1985
		1986	=over 4
		1987
		1988	=item SIGCHLD
		1989
		1990	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1991	emulation for event loops that do not support them natively. Also, some
		1992	event loops install a similar handler.
		1993
		1994	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		1995	reset it to default, to avoid losing child exit statuses.
		1996
		1997	=item SIGPIPE
		1998
		1999	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2000	when AnyEvent gets loaded.
		2001
		2002	The rationale for this is that AnyEvent users usually do not really depend
		2003	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2004	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2005	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2006	some random socket.
		2007
		2008	The rationale for installing a no-op handler as opposed to ignoring it is
		2009	that this way, the handler will be restored to defaults on exec.
		2010
		2011	Feel free to install your own handler, or reset it to defaults.
		2012
		2013	=back
		2014
		2015	=cut
		2016
		2017	undef $SIG{CHLD}
		2018	if $SIG{CHLD} eq 'IGNORE';
		2019
		2020	$SIG{PIPE} = sub { }
		2021	unless defined $SIG{PIPE};
1545		2022
1546	=head1 FORK	2023	=head1 FORK
1547		2024
1548	Most event libraries are not fork-safe. The ones who are usually are	2025	Most event libraries are not fork-safe. The ones who are usually are
1549	because they rely on inefficient but fork-safe C<select> or C<poll>	2026	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1563	specified in the variable.	2040	specified in the variable.
1564		2041
1565	You can make AnyEvent completely ignore this variable by deleting it	2042	You can make AnyEvent completely ignore this variable by deleting it
1566	before the first watcher gets created, e.g. with a C<BEGIN> block:	2043	before the first watcher gets created, e.g. with a C<BEGIN> block:
1567		2044
1568	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2045	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1569		2046
1570	use AnyEvent;	2047	use AnyEvent;
1571		2048
1572	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2049	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1573	be used to probe what backend is used and gain other information (which is	2050	be used to probe what backend is used and gain other information (which is
1574	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2051	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2052	$ENV{PERL_ANYEVENT_STRICT}.
		2053
		2054	Note that AnyEvent will remove I<all> environment variables starting with
		2055	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2056	enabled.
		2057
		2058
		2059	=head1 BUGS
		2060
		2061	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2062	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2063	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2064	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2065	pronounced).
1575		2066
1576		2067
1577	=head1 SEE ALSO	2068	=head1 SEE ALSO
1578		2069
1579	Utility functions: L<AnyEvent::Util>.	2070	Utility functions: L<AnyEvent::Util>.
…		…
1596	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2087	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1597		2088
1598		2089
1599	=head1 AUTHOR	2090	=head1 AUTHOR
1600		2091
1601	Marc Lehmann <schmorp@schmorp.de>	2092	Marc Lehmann <schmorp@schmorp.de>
1602	http://home.schmorp.de/	2093	http://home.schmorp.de/
1603		2094
1604	=cut	2095	=cut
1605		2096
1606	1	2097	1
1607		2098

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC vs. Revision 1.221 by root, Fri Jun 26 06:33:17 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.137 by root, Mon May 26 03:27:52 2008 UTC vs.
Revision 1.221 by root, Fri Jun 26 06:33:17 2009 UTC