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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 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
121	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
122	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
123	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
124	is in control).	148	is in control).
125		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
126	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
127	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
128	to it).	158	to it).
129		159
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
133	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.
134		164
135	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
136		166
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
139	undef $w;	169	undef $w;
140	});	170	});
141		171
142	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,
143	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
144	declared.	174	declared.
145		175
146	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
147		177
148	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
149	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
150		180
151	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
152	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
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
154	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.
155	becomes ready.
156		192
157	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
160		196
…		…
164		200
165	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
166	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
167	handles.	203	handles.
168		204
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	210	warn "read: $input\n";
175	undef $w;	211	undef $w;
176	});	212	});
…		…
186		222
187	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
190		226
191	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
192	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
193	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.
194		232
195	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.
196		236
197	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	240	warn "timeout\n";
200	});	241	});
201		242
202	# to cancel the timer:	243	# to cancel the timer:
203	undef $w;	244	undef $w;
204		245
205	Example 2:
206
207	# 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.
208	my $w;
209		247
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
213	};	250	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		251
218	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
219		253
220	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
221	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
…		…
243		277
244	This returns the "current wallclock time" as a fractional number of	278	This returns the "current wallclock time" as a fractional number of
245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>	279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
246	return, and the result is guaranteed to be compatible with those).	280	return, and the result is guaranteed to be compatible with those).
247		281
248	It progresses independently of any event loop processing.	282	It progresses independently of any event loop processing, i.e. each call
249		283	will check the system clock, which usually gets updated frequently.
250	In almost all cases (in all cases if you don't care), this is the function
251	to call when you want to know the current time.
252		284
253	=item AnyEvent->now	285	=item AnyEvent->now
254		286
255	This also returns the "current wallclock time", but unlike C<time>, above,	287	This also returns the "current wallclock time", but unlike C<time>, above,
256	this value might change only once per event loop iteration, depending on	288	this value might change only once per event loop iteration, depending on
257	the event loop (most return the same time as C<time>, above). This is the	289	the event loop (most return the same time as C<time>, above). This is the
258	time that AnyEvent timers get scheduled against.	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.
259		301
260	For a practical example of when these times differ, consider L<Event::Lib>	302	For a practical example of when these times differ, consider L<Event::Lib>
261	and L<EV> and the following set-up:	303	and L<EV> and the following set-up:
262		304
263	The event loop is running and has just invoked one of your callback at	305	The event loop is running and has just invoked one of your callback at
…		…
268		310
269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will	311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
270	both return C<501>, because that is the current time, and the timer will	312	both return C<501>, because that is the current time, and the timer will
271	be scheduled to fire at time=504 (C<501> + C<3>).	313	be scheduled to fire at time=504 (C<501> + C<3>).
272		314
273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current	315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the	316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
275	last event processing phase started. With L<EV>, your timer gets scheduled	317	last event processing phase started. With L<EV>, your timer gets scheduled
276	to run at time=503 (C<500> + C<3>).	318	to run at time=503 (C<500> + C<3>).
277		319
278	In one sense, L<Event::Lib> is more exact, as it uses the current time	320	In one sense, L<Event::Lib> is more exact, as it uses the current time
279	regardless of any delays introduced by event processing. However, most	321	regardless of any delays introduced by event processing. However, most
280	callbacks do not expect large delays in processing, so this causes a	322	callbacks do not expect large delays in processing, so this causes a
281	higher drift (and a lot more syscalls to get the current time).	323	higher drift (and a lot more system calls to get the current time).
282		324
283	In another sense, L<EV> is more exact, as your timer will be scheduled at	325	In another sense, L<EV> is more exact, as your timer will be scheduled at
284	the same time, regardless of how long event processing actually took.	326	the same time, regardless of how long event processing actually took.
285		327
286	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
287	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
289	account.	331	account.
290		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
291	=back	348	=back
292		349
293	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
294		351
295	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
296	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
297	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
298		355
299	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
300	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
301	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
302		359
…		…
318	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
319		376
320	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.
321		378
322	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
323	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
324	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
325	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
326	and exit status (as returned by waitpid), so unlike other watcher types,	383
327	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).
328		392
329	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
330	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
331	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
332		396
333	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
334	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
335	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.
336		403
337	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
338	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
339	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>).
340		408
341	Example: fork a process and wait for it	409	Example: fork a process and wait for it
342		410
343	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
344		412
345	my $pid = fork or exit 5;	413	my $pid = fork or exit 5;
346		414
347	my $w = AnyEvent->child (	415	my $w = AnyEvent->child (
348	pid => $pid,	416	pid => $pid,
349	cb => sub {	417	cb => sub {
350	my ($pid, $status) = @_;	418	my ($pid, $status) = @_;
351	warn "pid $pid exited with status $status";	419	warn "pid $pid exited with status $status";
352	$done->send;	420	$done->send;
353	},	421	},
354	);	422	);
355		423
356	# do something else, then wait for process exit	424	# do something else, then wait for process exit
357	$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	});
358		461
359	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
360		463
361	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
362	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
…		…
368	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
369	because they represent a condition that must become true.	472	because they represent a condition that must become true.
370		473
371	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
372	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
373	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
374	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
375		480
376	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
377	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
378	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<<
379	->send >> method).	484	->send >> method).
…		…
435		540
436	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
437	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
438	$done->recv;	543	$done->recv;
439		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
440	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
441		563
442	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
443	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
444	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
…		…
577	=item $bool = $cv->ready	699	=item $bool = $cv->ready
578		700
579	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
580	C<croak> have been called.	702	C<croak> have been called.
581		703
582	=item $cb = $cv->cb ([new callback])	704	=item $cb = $cv->cb ($cb->($cv))
583		705
584	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
585	replaces it before doing so.	707	replaces it before doing so.
586		708
587	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
588	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
589	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.
590		713
591	=back	714	=back
592		715
593	=head1 GLOBAL VARIABLES AND FUNCTIONS	716	=head1 GLOBAL VARIABLES AND FUNCTIONS
594		717
…		…
611	AnyEvent::Impl::Tk based on Tk, very bad choice.	734	AnyEvent::Impl::Tk based on Tk, very bad choice.
612	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).
613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	736	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
614	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.
615		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
616	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
617	watching file handles. However, you can use WxWidgets through the	744	watching file handles. However, you can use WxWidgets through the
618	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
619	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
620	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
…		…
723	=item L<AnyEvent::Util>	850	=item L<AnyEvent::Util>
724		851
725	Contains various utility functions that replace often-used but blocking	852	Contains various utility functions that replace often-used but blocking
726	functions such as C<inet_aton> by event-/callback-based versions.	853	functions such as C<inet_aton> by event-/callback-based versions.
727		854
728	=item L<AnyEvent::Handle>
729
730	Provide read and write buffers and manages watchers for reads and writes.
731
732	=item L<AnyEvent::Socket>	855	=item L<AnyEvent::Socket>
733		856
734	Provides various utility functions for (internet protocol) sockets,	857	Provides various utility functions for (internet protocol) sockets,
735	addresses and name resolution. Also functions to create non-blocking tcp	858	addresses and name resolution. Also functions to create non-blocking tcp
736	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.
737		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
738	=item L<AnyEvent::DNS>	867	=item L<AnyEvent::DNS>
739		868
740	Provides rich asynchronous DNS resolver capabilities.	869	Provides rich asynchronous DNS resolver capabilities.
741		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
742	=item L<AnyEvent::HTTPD>	876	=item L<AnyEvent::HTTPD>
743		877
744	Provides a simple web application server framework.	878	Provides a simple web application server framework.
745		879
746	=item L<AnyEvent::FastPing>	880	=item L<AnyEvent::FastPing>
747		881
748	The fastest ping in the west.	882	The fastest ping in the west.
749		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
750	=item L<Net::IRC3>	908	=item L<AnyEvent::IRC>
751		909
752	AnyEvent based IRC client module family.	910	AnyEvent based IRC client module family (replacing the older Net::IRC3).
753		911
754	=item L<Net::XMPP2>	912	=item L<Net::XMPP2>
755		913
756	AnyEvent based XMPP (Jabber protocol) module family.	914	AnyEvent based XMPP (Jabber protocol) module family.
757		915
…		…
766		924
767	=item L<Coro>	925	=item L<Coro>
768		926
769	Has special support for AnyEvent via L<Coro::AnyEvent>.	927	Has special support for AnyEvent via L<Coro::AnyEvent>.
770		928
771	=item L<AnyEvent::AIO>, L<IO::AIO>
772
773	Truly asynchronous I/O, should be in the toolbox of every event
774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
775	together.
776
777	=item L<AnyEvent::BDB>, L<BDB>
778
779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
780	IO::AIO and AnyEvent together.
781
782	=item L<IO::Lambda>	929	=item L<IO::Lambda>
783		930
784	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.
785		932
786	=back	933	=back
…		…
788	=cut	935	=cut
789		936
790	package AnyEvent;	937	package AnyEvent;
791		938
792	no warnings;	939	no warnings;
793	use strict;	940	use strict qw(vars subs);
794		941
795	use Carp;	942	use Carp;
796		943
797	our $VERSION = '4.05';	944	our $VERSION = 4.412;
798	our $MODEL;	945	our $MODEL;
799		946
800	our $AUTOLOAD;	947	our $AUTOLOAD;
801	our @ISA;	948	our @ISA;
802		949
803	our @REGISTRY;	950	our @REGISTRY;
804		951
805	our $WIN32;	952	our $WIN32;
806		953
807	BEGIN {	954	BEGIN {
808	my $win32 = ! ! ($^O =~ /mswin32/i);	955	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
809	eval "sub WIN32(){ $win32 }";	956	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		957
		958	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		959	if ${^TAINT};
810	}	960	}
811		961
812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	962	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
813		963
814	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	964	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	982	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	983	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	984	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
835	[Wx:: => AnyEvent::Impl::POE::],	985	[Wx:: => AnyEvent::Impl::POE::],
836	[Prima:: => AnyEvent::Impl::POE::],	986	[Prima:: => AnyEvent::Impl::POE::],
		987	# IO::Async is just too broken - we would need workaorunds for its
		988	# byzantine signal and broken child handling, among others.
		989	# IO::Async is rather hard to detect, as it doesn't have any
		990	# obvious default class.
		991	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		992	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		993	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
837	);	994	);
838		995
839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	996	our %method = map +($_ => 1),
		997	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
840		998
841	our @post_detect;	999	our @post_detect;
842		1000
843	sub post_detect(&) {	1001	sub post_detect(&) {
844	my ($cb) = @_;	1002	my ($cb) = @_;
…		…
849	1	1007	1
850	} else {	1008	} else {
851	push @post_detect, $cb;	1009	push @post_detect, $cb;
852		1010
853	defined wantarray	1011	defined wantarray
854	? bless \$cb, "AnyEvent::Util::PostDetect"	1012	? bless \$cb, "AnyEvent::Util::postdetect"
855	: ()	1013	: ()
856	}	1014	}
857	}	1015	}
858		1016
859	sub AnyEvent::Util::PostDetect::DESTROY {	1017	sub AnyEvent::Util::postdetect::DESTROY {
860	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1018	@post_detect = grep $_ != ${$_[0]}, @post_detect;
861	}	1019	}
862		1020
863	sub detect() {	1021	sub detect() {
864	unless ($MODEL) {	1022	unless ($MODEL) {
…		…
901	last;	1059	last;
902	}	1060	}
903	}	1061	}
904		1062
905	$MODEL	1063	$MODEL
906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1064	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
907	}	1065	}
908	}	1066	}
909		1067
		1068	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1069
910	unshift @ISA, $MODEL;	1070	unshift @ISA, $MODEL;
911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1071
		1072	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
912		1073
913	(shift @post_detect)->() while @post_detect;	1074	(shift @post_detect)->() while @post_detect;
914	}	1075	}
915		1076
916	$MODEL	1077	$MODEL
…		…
926		1087
927	my $class = shift;	1088	my $class = shift;
928	$class->$func (@_);	1089	$class->$func (@_);
929	}	1090	}
930		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
931	package AnyEvent::Base;	1111	package AnyEvent::Base;
932		1112
933	# default implementation for now and time	1113	# default implementations for many methods
934		1114
935	use Time::HiRes ();	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	}
936		1123
937	sub time { Time::HiRes::time }	1124	sub time { _time }
938	sub now { Time::HiRes::time }	1125	sub now { _time }
		1126	sub now_update { }
939		1127
940	# default implementation for ->condvar	1128	# default implementation for ->condvar
941		1129
942	sub condvar {	1130	sub condvar {
943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1131	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
944	}	1132	}
945		1133
946	# default implementation for ->signal	1134	# default implementation for ->signal
947		1135
948	our %SIG_CB;	1136	our ($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	}
949		1148
950	sub signal {	1149	sub signal {
951	my (undef, %arg) = @_;	1150	my (undef, %arg) = @_;
952		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
953	my $signal = uc $arg{signal}	1177	my $signal = uc $arg{signal}
954	or Carp::croak "required option 'signal' is missing";	1178	or Carp::croak "required option 'signal' is missing";
955		1179
956	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1180	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
957	$SIG{$signal} \|\|= sub {	1181	$SIG{$signal} \|\|= sub {
958	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1182	local $!;
		1183	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1184	undef $SIG_EV{$signal};
959	};	1185	};
960		1186
961	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1187	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
962	}	1188	}
963		1189
964	sub AnyEvent::Base::Signal::DESTROY {	1190	sub AnyEvent::Base::signal::DESTROY {
965	my ($signal, $cb) = @{$_[0]};	1191	my ($signal, $cb) = @{$_[0]};
966		1192
967	delete $SIG_CB{$signal}{$cb};	1193	delete $SIG_CB{$signal}{$cb};
968		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.
969	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1198	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
970	}	1199	}
971		1200
972	# default implementation for ->child	1201	# default implementation for ->child
973		1202
974	our %PID_CB;	1203	our %PID_CB;
975	our $CHLD_W;	1204	our $CHLD_W;
976	our $CHLD_DELAY_W;	1205	our $CHLD_DELAY_W;
977	our $PID_IDLE;
978	our $WNOHANG;	1206	our $WNOHANG;
979		1207
980	sub _child_wait {	1208	sub _sigchld {
981	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1209	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
982	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1210	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
983	(values %{ $PID_CB{0} \|\| {} });	1211	(values %{ $PID_CB{0} \|\| {} });
984	}	1212	}
985
986	undef $PID_IDLE;
987	}
988
989	sub _sigchld {
990	# make sure we deliver these changes "synchronous" with the event loop.
991	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
992	undef $CHLD_DELAY_W;
993	&_child_wait;
994	});
995	}	1213	}
996		1214
997	sub child {	1215	sub child {
998	my (undef, %arg) = @_;	1216	my (undef, %arg) = @_;
999		1217
1000	defined (my $pid = $arg{pid} + 0)	1218	defined (my $pid = $arg{pid} + 0)
1001	or Carp::croak "required option 'pid' is missing";	1219	or Carp::croak "required option 'pid' is missing";
1002		1220
1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1221	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1004		1222
1005	unless ($WNOHANG) {
1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1223	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1007	}
1008		1224
1009	unless ($CHLD_W) {	1225	unless ($CHLD_W) {
1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1226	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1011	# child could be a zombie already, so make at least one round	1227	# child could be a zombie already, so make at least one round
1012	&_sigchld;	1228	&_sigchld;
1013	}	1229	}
1014		1230
1015	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1231	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1016	}	1232	}
1017		1233
1018	sub AnyEvent::Base::Child::DESTROY {	1234	sub AnyEvent::Base::child::DESTROY {
1019	my ($pid, $cb) = @{$_[0]};	1235	my ($pid, $cb) = @{$_[0]};
1020		1236
1021	delete $PID_CB{$pid}{$cb};	1237	delete $PID_CB{$pid}{$cb};
1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1238	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1023		1239
1024	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]};
1025	}	1277	}
1026		1278
1027	package AnyEvent::CondVar;	1279	package AnyEvent::CondVar;
1028		1280
1029	our @ISA = AnyEvent::CondVar::Base::;	1281	our @ISA = AnyEvent::CondVar::Base::;
…		…
1081	}	1333	}
1082		1334
1083	# undocumented/compatibility with pre-3.4	1335	# undocumented/compatibility with pre-3.4
1084	*broadcast = \&send;	1336	*broadcast = \&send;
1085	*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
1086		1448
1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1449	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1088		1450
1089	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
1090	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
…		…
1124		1486
1125	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
1126	condition variables: code blocking while waiting for a condition will	1488	condition variables: code blocking while waiting for a condition will
1127	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
1128	not be done in an interactive application, so it makes sense.	1490	not be done in an interactive application, so it makes sense.
1129
1130	=head1 ENVIRONMENT VARIABLES
1131
1132	The following environment variables are used by this module:
1133
1134	=over 4
1135
1136	=item C<PERL_ANYEVENT_VERBOSE>
1137
1138	By default, AnyEvent will be completely silent except in fatal
1139	conditions. You can set this environment variable to make AnyEvent more
1140	talkative.
1141
1142	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1143	conditions, such as not being able to load the event model specified by
1144	C<PERL_ANYEVENT_MODEL>.
1145
1146	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1147	model it chooses.
1148
1149	=item C<PERL_ANYEVENT_MODEL>
1150
1151	This can be used to specify the event model to be used by AnyEvent, before
1152	auto detection and -probing kicks in. It must be a string consisting
1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1154	and the resulting module name is loaded and if the load was successful,
1155	used as event model. If it fails to load AnyEvent will proceed with
1156	auto detection and -probing.
1157
1158	This functionality might change in future versions.
1159
1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1161	could start your program like this:
1162
1163	PERL_ANYEVENT_MODEL=Perl perl ...
1164
1165	=item C<PERL_ANYEVENT_PROTOCOLS>
1166
1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1169	of auto probing).
1170
1171	Must be set to a comma-separated list of protocols or address families,
1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1173	used, and preference will be given to protocols mentioned earlier in the
1174	list.
1175
1176	This variable can effectively be used for denial-of-service attacks
1177	against local programs (e.g. when setuid), although the impact is likely
1178	small, as the program has to handle connection errors already-
1179
1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1182	- only support IPv4, never try to resolve or contact IPv6
1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1184	IPv6, but prefer IPv6 over IPv4.
1185
1186	=item C<PERL_ANYEVENT_EDNS0>
1187
1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1189	for DNS. This extension is generally useful to reduce DNS traffic, but
1190	some (broken) firewalls drop such DNS packets, which is why it is off by
1191	default.
1192
1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1194	EDNS0 in its DNS requests.
1195
1196	=item C<PERL_ANYEVENT_MAX_FORKS>
1197
1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1199	will create in parallel.
1200
1201	=back
1202		1491
1203	=head1 EXAMPLE PROGRAM	1492	=head1 EXAMPLE PROGRAM
1204		1493
1205	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
1206	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
…		…
1400	watcher.	1689	watcher.
1401		1690
1402	=head3 Results	1691	=head3 Results
1403		1692
1404	name watchers bytes create invoke destroy comment	1693	name watchers bytes create invoke destroy comment
1405	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
1406	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
1407	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
1408	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
1409	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
1410	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
1411	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1700	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1412	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1701	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1413	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1702	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1414	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1703	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1415		1704
1416	=head3 Discussion	1705	=head3 Discussion
1417		1706
1418	The benchmark does I<not> measure scalability of the event loop very	1707	The benchmark does I<not> measure scalability of the event loop very
1419	well. For example, a select-based event loop (such as the pure perl one)	1708	well. For example, a select-based event loop (such as the pure perl one)
…		…
1620	=item * C-based event loops perform very well with small number of	1909	=item * C-based event loops perform very well with small number of
1621	watchers, as the management overhead dominates.	1910	watchers, as the management overhead dominates.
1622		1911
1623	=back	1912	=back
1624		1913
		1914	=head2 THE IO::Lambda BENCHMARK
		1915
		1916	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1917	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1918	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1919	shouldn't come as a surprise to anybody). As such, the benchmark is
		1920	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1921	very optimal. But how would AnyEvent compare when used without the extra
		1922	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1923
		1924	The benchmark itself creates an echo-server, and then, for 500 times,
		1925	connects to the echo server, sends a line, waits for the reply, and then
		1926	creates the next connection. This is a rather bad benchmark, as it doesn't
		1927	test the efficiency of the framework or much non-blocking I/O, but it is a
		1928	benchmark nevertheless.
		1929
		1930	name runtime
		1931	Lambda/select 0.330 sec
		1932	+ optimized 0.122 sec
		1933	Lambda/AnyEvent 0.327 sec
		1934	+ optimized 0.138 sec
		1935	Raw sockets/select 0.077 sec
		1936	POE/select, components 0.662 sec
		1937	POE/select, raw sockets 0.226 sec
		1938	POE/select, optimized 0.404 sec
		1939
		1940	AnyEvent/select/nb 0.085 sec
		1941	AnyEvent/EV/nb 0.068 sec
		1942	+state machine 0.134 sec
		1943
		1944	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1945	benchmarks actually make blocking connects and use 100% blocking I/O,
		1946	defeating the purpose of an event-based solution. All of the newly
		1947	written AnyEvent benchmarks use 100% non-blocking connects (using
		1948	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1949	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		1950	generally require a lot more bookkeeping and event handling than blocking
		1951	connects (which involve a single syscall only).
		1952
		1953	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1954	offers similar expressive power as POE and IO::Lambda, using conventional
		1955	Perl syntax. This means that both the echo server and the client are 100%
		1956	non-blocking, further placing it at a disadvantage.
		1957
		1958	As you can see, the AnyEvent + EV combination even beats the
		1959	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1960	backend easily beats IO::Lambda and POE.
		1961
		1962	And even the 100% non-blocking version written using the high-level (and
		1963	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		1964	large margin, even though it does all of DNS, tcp-connect and socket I/O
		1965	in a non-blocking way.
		1966
		1967	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		1968	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		1969	part of the IO::lambda distribution and were used without any changes.
		1970
		1971
		1972	=head1 SIGNALS
		1973
		1974	AnyEvent currently installs handlers for these signals:
		1975
		1976	=over 4
		1977
		1978	=item SIGCHLD
		1979
		1980	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1981	emulation for event loops that do not support them natively. Also, some
		1982	event loops install a similar handler.
		1983
		1984	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		1985	reset it to default, to avoid losing child exit statuses.
		1986
		1987	=item SIGPIPE
		1988
		1989	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1990	when AnyEvent gets loaded.
		1991
		1992	The rationale for this is that AnyEvent users usually do not really depend
		1993	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1994	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1995	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1996	some random socket.
		1997
		1998	The rationale for installing a no-op handler as opposed to ignoring it is
		1999	that this way, the handler will be restored to defaults on exec.
		2000
		2001	Feel free to install your own handler, or reset it to defaults.
		2002
		2003	=back
		2004
		2005	=cut
		2006
		2007	undef $SIG{CHLD}
		2008	if $SIG{CHLD} eq 'IGNORE';
		2009
		2010	$SIG{PIPE} = sub { }
		2011	unless defined $SIG{PIPE};
1625		2012
1626	=head1 FORK	2013	=head1 FORK
1627		2014
1628	Most event libraries are not fork-safe. The ones who are usually are	2015	Most event libraries are not fork-safe. The ones who are usually are
1629	because they rely on inefficient but fork-safe C<select> or C<poll>	2016	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1643	specified in the variable.	2030	specified in the variable.
1644		2031
1645	You can make AnyEvent completely ignore this variable by deleting it	2032	You can make AnyEvent completely ignore this variable by deleting it
1646	before the first watcher gets created, e.g. with a C<BEGIN> block:	2033	before the first watcher gets created, e.g. with a C<BEGIN> block:
1647		2034
1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2035	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1649		2036
1650	use AnyEvent;	2037	use AnyEvent;
1651		2038
1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2039	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1653	be used to probe what backend is used and gain other information (which is	2040	be used to probe what backend is used and gain other information (which is
1654	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2041	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2042	$ENV{PERL_ANYEVENT_STRICT}.
		2043
		2044	Note that AnyEvent will remove I<all> environment variables starting with
		2045	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2046	enabled.
		2047
		2048
		2049	=head1 BUGS
		2050
		2051	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2052	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2053	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2054	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2055	pronounced).
1655		2056
1656		2057
1657	=head1 SEE ALSO	2058	=head1 SEE ALSO
1658		2059
1659	Utility functions: L<AnyEvent::Util>.	2060	Utility functions: L<AnyEvent::Util>.
…		…
1676	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2077	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1677		2078
1678		2079
1679	=head1 AUTHOR	2080	=head1 AUTHOR
1680		2081
1681	Marc Lehmann <schmorp@schmorp.de>	2082	Marc Lehmann <schmorp@schmorp.de>
1682	http://home.schmorp.de/	2083	http://home.schmorp.de/
1683		2084
1684	=cut	2085	=cut
1685		2086
1686	1	2087	1
1687		2088

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs. Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC vs.
Revision 1.219 by root, Thu Jun 25 11:16:08 2009 UTC