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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.152 by root, Tue Jun 3 09:02:46 2008 UTC vs.
Revision 1.228 by root, Wed Jul 8 01:11:12 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 });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
33		50
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
36		53
37	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
38	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
39	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
40	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,
41	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
42	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
43		61
44	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
45	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
46	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
47	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
48	model you use.	66	model you use.
49		67
50	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
51	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
52	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
53	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
54	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
55	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.
56		74
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	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
59	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
60	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,
61	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
62	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
63	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
64	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
65		83
66	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
67	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
68	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
69	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
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
128	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
129	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
130	is in control).	148	is in control).
131		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
132	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
133	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
134	to it).	158	to it).
135		159
136	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.
…		…
152	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
153		177
154	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
155	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
156		180
157	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, see below) to
		182	watch for events (AnyEvent might or might not keep a reference to this
		183	file 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
158	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
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
160	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.
161	becomes ready.
162		192
163	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
166		196
…		…
170		200
171	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
172	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
173	handles.	203	handles.
174		204
175	Example:
176
177	# 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
178	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
179	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
180	warn "read: $input\n";	210	warn "read: $input\n";
181	undef $w;	211	undef $w;
182	});	212	});
183		213
		214	=head3 GETTING A FILE HANDLE FROM A FILE DESCRIPTOR
		215
		216	It is not uncommon to only have a file descriptor, while AnyEvent requires
		217	a Perl file handle.
		218
		219	There are basically two methods to convert a file descriptor into a file handle. If you own
		220	the file descriptor, you can open it with C<&=>, as in:
		221
		222	open my $fh, "<&=$fileno" or die "xxx: §!";
		223
		224	This will "own" the file descriptor, meaning that when C<$fh> is
		225	destroyed, it will automatically close the C<$fileno>. Also, note that
		226	the open mode (read, write, read/write) must correspond with how the
		227	underlying file descriptor was opened.
		228
		229	In many cases, taking over the file descriptor is now what you want, in
		230	which case the only alternative is to dup the file descriptor:
		231
		232	open my $fh, "<&$fileno" or die "xxx: $!";
		233
		234	This has the advantage of not closing the file descriptor and the
		235	disadvantage of making a slow copy.
		236
184	=head2 TIME WATCHERS	237	=head2 TIME WATCHERS
185		238
186	You can create a time watcher by calling the C<< AnyEvent->timer >>	239	You can create a time watcher by calling the C<< AnyEvent->timer >>
187	method with the following mandatory arguments:	240	method with the following mandatory arguments:
188		241
…		…
192		245
193	Although the callback might get passed parameters, their value and	246	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	247	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	248	callbacks cannot use arguments passed to time watcher callbacks.
196		249
197	The timer callback will be invoked at most once: if you want a repeating	250	The callback will normally be invoked once only. If you specify another
198	timer you have to create a new watcher (this is a limitation by both Tk	251	parameter, C<interval>, as a strictly positive number (> 0), then the
199	and Glib).	252	callback will be invoked regularly at that interval (in fractional
		253	seconds) after the first invocation. If C<interval> is specified with a
		254	false value, then it is treated as if it were missing.
200		255
201	Example:	256	The callback will be rescheduled before invoking the callback, but no
		257	attempt is done to avoid timer drift in most backends, so the interval is
		258	only approximate.
202		259
203	# fire an event after 7.7 seconds	260	Example: fire an event after 7.7 seconds.
		261
204	my $w = AnyEvent->timer (after => 7.7, cb => sub {	262	my $w = AnyEvent->timer (after => 7.7, cb => sub {
205	warn "timeout\n";	263	warn "timeout\n";
206	});	264	});
207		265
208	# to cancel the timer:	266	# to cancel the timer:
209	undef $w;	267	undef $w;
210		268
211	Example 2:
212
213	# fire an event after 0.5 seconds, then roughly every second	269	Example 2: fire an event after 0.5 seconds, then roughly every second.
214	my $w;
215		270
216	my $cb = sub {
217	# cancel the old timer while creating a new one
218	$w = AnyEvent->timer (after => 1, cb => $cb);	271	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		272	warn "timeout\n";
219	};	273	};
220
221	# start the "loop" by creating the first watcher
222	$w = AnyEvent->timer (after => 0.5, cb => $cb);
223		274
224	=head3 TIMING ISSUES	275	=head3 TIMING ISSUES
225		276
226	There are two ways to handle timers: based on real time (relative, "fire	277	There are two ways to handle timers: based on real time (relative, "fire
227	in 10 seconds") and based on wallclock time (absolute, "fire at 12	278	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
300	In either case, if you care (and in most cases, you don't), then you	351	In either case, if you care (and in most cases, you don't), then you
301	can get whatever behaviour you want with any event loop, by taking the	352	can get whatever behaviour you want with any event loop, by taking the
302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	353	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
303	account.	354	account.
304		355
		356	=item AnyEvent->now_update
		357
		358	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		359	the current time for each loop iteration (see the discussion of L<<
		360	AnyEvent->now >>, above).
		361
		362	When a callback runs for a long time (or when the process sleeps), then
		363	this "current" time will differ substantially from the real time, which
		364	might affect timers and time-outs.
		365
		366	When this is the case, you can call this method, which will update the
		367	event loop's idea of "current time".
		368
		369	Note that updating the time I<might> cause some events to be handled.
		370
305	=back	371	=back
306		372
307	=head2 SIGNAL WATCHERS	373	=head2 SIGNAL WATCHERS
308		374
309	You can watch for signals using a signal watcher, C<signal> is the signal	375	You can watch for signals using a signal watcher, C<signal> is the signal
310	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	376	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
311	be invoked whenever a signal occurs.	377	callback to be invoked whenever a signal occurs.
312		378
313	Although the callback might get passed parameters, their value and	379	Although the callback might get passed parameters, their value and
314	presence is undefined and you cannot rely on them. Portable AnyEvent	380	presence is undefined and you cannot rely on them. Portable AnyEvent
315	callbacks cannot use arguments passed to signal watcher callbacks.	381	callbacks cannot use arguments passed to signal watcher callbacks.
316		382
…		…
332	=head2 CHILD PROCESS WATCHERS	398	=head2 CHILD PROCESS WATCHERS
333		399
334	You can also watch on a child process exit and catch its exit status.	400	You can also watch on a child process exit and catch its exit status.
335		401
336	The child process is specified by the C<pid> argument (if set to C<0>, it	402	The child process is specified by the C<pid> argument (if set to C<0>, it
337	watches for any child process exit). The watcher will trigger as often	403	watches for any child process exit). The watcher will triggered only when
338	as status change for the child are received. This works by installing a	404	the child process has finished and an exit status is available, not on
339	signal handler for C<SIGCHLD>. The callback will be called with the pid	405	any trace events (stopped/continued).
340	and exit status (as returned by waitpid), so unlike other watcher types,	406
341	you I<can> rely on child watcher callback arguments.	407	The callback will be called with the pid and exit status (as returned by
		408	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		409	callback arguments.
		410
		411	This watcher type works by installing a signal handler for C<SIGCHLD>,
		412	and since it cannot be shared, nothing else should use SIGCHLD or reap
		413	random child processes (waiting for specific child processes, e.g. inside
		414	C<system>, is just fine).
342		415
343	There is a slight catch to child watchers, however: you usually start them	416	There is a slight catch to child watchers, however: you usually start them
344	I<after> the child process was created, and this means the process could	417	I<after> the child process was created, and this means the process could
345	have exited already (and no SIGCHLD will be sent anymore).	418	have exited already (and no SIGCHLD will be sent anymore).
346		419
347	Not all event models handle this correctly (POE doesn't), but even for	420	Not all event models handle this correctly (neither POE nor IO::Async do,
		421	see their AnyEvent::Impl manpages for details), but even for event models
348	event models that I<do> handle this correctly, they usually need to be	422	that I<do> handle this correctly, they usually need to be loaded before
349	loaded before the process exits (i.e. before you fork in the first place).	423	the process exits (i.e. before you fork in the first place). AnyEvent's
		424	pure perl event loop handles all cases correctly regardless of when you
		425	start the watcher.
350		426
351	This means you cannot create a child watcher as the very first thing in an	427	This means you cannot create a child watcher as the very first
352	AnyEvent program, you I<have> to create at least one watcher before you	428	thing in an AnyEvent program, you I<have> to create at least one
353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	429	watcher before you C<fork> the child (alternatively, you can call
		430	C<AnyEvent::detect>).
354		431
355	Example: fork a process and wait for it	432	Example: fork a process and wait for it
356		433
357	my $done = AnyEvent->condvar;	434	my $done = AnyEvent->condvar;
358		435
…		…
368	);	445	);
369		446
370	# do something else, then wait for process exit	447	# do something else, then wait for process exit
371	$done->recv;	448	$done->recv;
372		449
		450	=head2 IDLE WATCHERS
		451
		452	Sometimes there is a need to do something, but it is not so important
		453	to do it instantly, but only when there is nothing better to do. This
		454	"nothing better to do" is usually defined to be "no other events need
		455	attention by the event loop".
		456
		457	Idle watchers ideally get invoked when the event loop has nothing
		458	better to do, just before it would block the process to wait for new
		459	events. Instead of blocking, the idle watcher is invoked.
		460
		461	Most event loops unfortunately do not really support idle watchers (only
		462	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		463	will simply call the callback "from time to time".
		464
		465	Example: read lines from STDIN, but only process them when the
		466	program is otherwise idle:
		467
		468	my @lines; # read data
		469	my $idle_w;
		470	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		471	push @lines, scalar <STDIN>;
		472
		473	# start an idle watcher, if not already done
		474	$idle_w \|\|= AnyEvent->idle (cb => sub {
		475	# handle only one line, when there are lines left
		476	if (my $line = shift @lines) {
		477	print "handled when idle: $line";
		478	} else {
		479	# otherwise disable the idle watcher again
		480	undef $idle_w;
		481	}
		482	});
		483	});
		484
373	=head2 CONDITION VARIABLES	485	=head2 CONDITION VARIABLES
374		486
375	If you are familiar with some event loops you will know that all of them	487	If you are familiar with some event loops you will know that all of them
376	require you to run some blocking "loop", "run" or similar function that	488	require you to run some blocking "loop", "run" or similar function that
377	will actively watch for new events and call your callbacks.	489	will actively watch for new events and call your callbacks.
…		…
382	The instrument to do that is called a "condition variable", so called	494	The instrument to do that is called a "condition variable", so called
383	because they represent a condition that must become true.	495	because they represent a condition that must become true.
384		496
385	Condition variables can be created by calling the C<< AnyEvent->condvar	497	Condition variables can be created by calling the C<< AnyEvent->condvar
386	>> method, usually without arguments. The only argument pair allowed is	498	>> method, usually without arguments. The only argument pair allowed is
		499
387	C<cb>, which specifies a callback to be called when the condition variable	500	C<cb>, which specifies a callback to be called when the condition variable
388	becomes true.	501	becomes true, with the condition variable as the first argument (but not
		502	the results).
389		503
390	After creation, the condition variable is "false" until it becomes "true"	504	After creation, the condition variable is "false" until it becomes "true"
391	by calling the C<send> method (or calling the condition variable as if it	505	by calling the C<send> method (or calling the condition variable as if it
392	were a callback, read about the caveats in the description for the C<<	506	were a callback, read about the caveats in the description for the C<<
393	->send >> method).	507	->send >> method).
…		…
449		563
450	my $done = AnyEvent->condvar;	564	my $done = AnyEvent->condvar;
451	my $delay = AnyEvent->timer (after => 5, cb => $done);	565	my $delay = AnyEvent->timer (after => 5, cb => $done);
452	$done->recv;	566	$done->recv;
453		567
		568	Example: Imagine an API that returns a condvar and doesn't support
		569	callbacks. This is how you make a synchronous call, for example from
		570	the main program:
		571
		572	use AnyEvent::CouchDB;
		573
		574	...
		575
		576	my @info = $couchdb->info->recv;
		577
		578	And this is how you would just ste a callback to be called whenever the
		579	results are available:
		580
		581	$couchdb->info->cb (sub {
		582	my @info = $_[0]->recv;
		583	});
		584
454	=head3 METHODS FOR PRODUCERS	585	=head3 METHODS FOR PRODUCERS
455		586
456	These methods should only be used by the producing side, i.e. the	587	These methods should only be used by the producing side, i.e. the
457	code/module that eventually sends the signal. Note that it is also	588	code/module that eventually sends the signal. Note that it is also
458	the producer side which creates the condvar in most cases, but it isn't	589	the producer side which creates the condvar in most cases, but it isn't
…		…
491		622
492	=item $cv->begin ([group callback])	623	=item $cv->begin ([group callback])
493		624
494	=item $cv->end	625	=item $cv->end
495		626
496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
497
498	These two methods can be used to combine many transactions/events into	627	These two methods can be used to combine many transactions/events into
499	one. For example, a function that pings many hosts in parallel might want	628	one. For example, a function that pings many hosts in parallel might want
500	to use a condition variable for the whole process.	629	to use a condition variable for the whole process.
501		630
502	Every call to C<< ->begin >> will increment a counter, and every call to	631	Every call to C<< ->begin >> will increment a counter, and every call to
503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	632	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
504	>>, the (last) callback passed to C<begin> will be executed. That callback	633	>>, the (last) callback passed to C<begin> will be executed. That callback
505	is I<supposed> to call C<< ->send >>, but that is not required. If no	634	is I<supposed> to call C<< ->send >>, but that is not required. If no
506	callback was set, C<send> will be called without any arguments.	635	callback was set, C<send> will be called without any arguments.
507		636
508	Let's clarify this with the ping example:	637	You can think of C<< $cv->send >> giving you an OR condition (one call
		638	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		639	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		640
		641	Let's start with a simple example: you have two I/O watchers (for example,
		642	STDOUT and STDERR for a program), and you want to wait for both streams to
		643	close before activating a condvar:
		644
		645	my $cv = AnyEvent->condvar;
		646
		647	$cv->begin; # first watcher
		648	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		649	defined sysread $fh1, my $buf, 4096
		650	or $cv->end;
		651	});
		652
		653	$cv->begin; # second watcher
		654	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		655	defined sysread $fh2, my $buf, 4096
		656	or $cv->end;
		657	});
		658
		659	$cv->recv;
		660
		661	This works because for every event source (EOF on file handle), there is
		662	one call to C<begin>, so the condvar waits for all calls to C<end> before
		663	sending.
		664
		665	The ping example mentioned above is slightly more complicated, as the
		666	there are results to be passwd back, and the number of tasks that are
		667	begung can potentially be zero:
509		668
510	my $cv = AnyEvent->condvar;	669	my $cv = AnyEvent->condvar;
511		670
512	my %result;	671	my %result;
513	$cv->begin (sub { $cv->send (\%result) });	672	$cv->begin (sub { $cv->send (\%result) });
…		…
533	loop, which serves two important purposes: first, it sets the callback	692	loop, which serves two important purposes: first, it sets the callback
534	to be called once the counter reaches C<0>, and second, it ensures that	693	to be called once the counter reaches C<0>, and second, it ensures that
535	C<send> is called even when C<no> hosts are being pinged (the loop	694	C<send> is called even when C<no> hosts are being pinged (the loop
536	doesn't execute once).	695	doesn't execute once).
537		696
538	This is the general pattern when you "fan out" into multiple subrequests:	697	This is the general pattern when you "fan out" into multiple (but
539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	698	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
540	is called at least once, and then, for each subrequest you start, call	699	the callback and ensure C<end> is called at least once, and then, for each
541	C<begin> and for each subrequest you finish, call C<end>.	700	subrequest you start, call C<begin> and for each subrequest you finish,
		701	call C<end>.
542		702
543	=back	703	=back
544		704
545	=head3 METHODS FOR CONSUMERS	705	=head3 METHODS FOR CONSUMERS
546		706
…		…
591	=item $bool = $cv->ready	751	=item $bool = $cv->ready
592		752
593	Returns true when the condition is "true", i.e. whether C<send> or	753	Returns true when the condition is "true", i.e. whether C<send> or
594	C<croak> have been called.	754	C<croak> have been called.
595		755
596	=item $cb = $cv->cb ([new callback])	756	=item $cb = $cv->cb ($cb->($cv))
597		757
598	This is a mutator function that returns the callback set and optionally	758	This is a mutator function that returns the callback set and optionally
599	replaces it before doing so.	759	replaces it before doing so.
600		760
601	The callback will be called when the condition becomes "true", i.e. when	761	The callback will be called when the condition becomes "true", i.e. when
…		…
626	AnyEvent::Impl::Tk based on Tk, very bad choice.	786	AnyEvent::Impl::Tk based on Tk, very bad choice.
627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	787	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	788	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
629	AnyEvent::Impl::POE based on POE, not generic enough for full support.	789	AnyEvent::Impl::POE based on POE, not generic enough for full support.
630		790
		791	# warning, support for IO::Async is only partial, as it is too broken
		792	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		793	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		794
631	There is no support for WxWidgets, as WxWidgets has no support for	795	There is no support for WxWidgets, as WxWidgets has no support for
632	watching file handles. However, you can use WxWidgets through the	796	watching file handles. However, you can use WxWidgets through the
633	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	797	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
634	second, which was considered to be too horrible to even consider for	798	second, which was considered to be too horrible to even consider for
635	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	799	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
738	=item L<AnyEvent::Util>	902	=item L<AnyEvent::Util>
739		903
740	Contains various utility functions that replace often-used but blocking	904	Contains various utility functions that replace often-used but blocking
741	functions such as C<inet_aton> by event-/callback-based versions.	905	functions such as C<inet_aton> by event-/callback-based versions.
742		906
743	=item L<AnyEvent::Handle>
744
745	Provide read and write buffers and manages watchers for reads and writes.
746
747	=item L<AnyEvent::Socket>	907	=item L<AnyEvent::Socket>
748		908
749	Provides various utility functions for (internet protocol) sockets,	909	Provides various utility functions for (internet protocol) sockets,
750	addresses and name resolution. Also functions to create non-blocking tcp	910	addresses and name resolution. Also functions to create non-blocking tcp
751	connections or tcp servers, with IPv6 and SRV record support and more.	911	connections or tcp servers, with IPv6 and SRV record support and more.
752		912
		913	=item L<AnyEvent::Handle>
		914
		915	Provide read and write buffers, manages watchers for reads and writes,
		916	supports raw and formatted I/O, I/O queued and fully transparent and
		917	non-blocking SSL/TLS.
		918
753	=item L<AnyEvent::DNS>	919	=item L<AnyEvent::DNS>
754		920
755	Provides rich asynchronous DNS resolver capabilities.	921	Provides rich asynchronous DNS resolver capabilities.
756		922
		923	=item L<AnyEvent::HTTP>
		924
		925	A simple-to-use HTTP library that is capable of making a lot of concurrent
		926	HTTP requests.
		927
757	=item L<AnyEvent::HTTPD>	928	=item L<AnyEvent::HTTPD>
758		929
759	Provides a simple web application server framework.	930	Provides a simple web application server framework.
760		931
761	=item L<AnyEvent::FastPing>	932	=item L<AnyEvent::FastPing>
762		933
763	The fastest ping in the west.	934	The fastest ping in the west.
764		935
		936	=item L<AnyEvent::DBI>
		937
		938	Executes L<DBI> requests asynchronously in a proxy process.
		939
		940	=item L<AnyEvent::AIO>
		941
		942	Truly asynchronous I/O, should be in the toolbox of every event
		943	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		944	together.
		945
		946	=item L<AnyEvent::BDB>
		947
		948	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		949	L<BDB> and AnyEvent together.
		950
		951	=item L<AnyEvent::GPSD>
		952
		953	A non-blocking interface to gpsd, a daemon delivering GPS information.
		954
		955	=item L<AnyEvent::IGS>
		956
		957	A non-blocking interface to the Internet Go Server protocol (used by
		958	L<App::IGS>).
		959
765	=item L<Net::IRC3>	960	=item L<AnyEvent::IRC>
766		961
767	AnyEvent based IRC client module family.	962	AnyEvent based IRC client module family (replacing the older Net::IRC3).
768		963
769	=item L<Net::XMPP2>	964	=item L<Net::XMPP2>
770		965
771	AnyEvent based XMPP (Jabber protocol) module family.	966	AnyEvent based XMPP (Jabber protocol) module family.
772		967
…		…
781		976
782	=item L<Coro>	977	=item L<Coro>
783		978
784	Has special support for AnyEvent via L<Coro::AnyEvent>.	979	Has special support for AnyEvent via L<Coro::AnyEvent>.
785		980
786	=item L<AnyEvent::AIO>, L<IO::AIO>
787
788	Truly asynchronous I/O, should be in the toolbox of every event
789	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
790	together.
791
792	=item L<AnyEvent::BDB>, L<BDB>
793
794	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
795	IO::AIO and AnyEvent together.
796
797	=item L<IO::Lambda>	981	=item L<IO::Lambda>
798		982
799	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	983	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
800		984
801	=back	985	=back
…		…
803	=cut	987	=cut
804		988
805	package AnyEvent;	989	package AnyEvent;
806		990
807	no warnings;	991	no warnings;
808	use strict;	992	use strict qw(vars subs);
809		993
810	use Carp;	994	use Carp;
811		995
812	our $VERSION = 4.12;	996	our $VERSION = 4.8;
813	our $MODEL;	997	our $MODEL;
814		998
815	our $AUTOLOAD;	999	our $AUTOLOAD;
816	our @ISA;	1000	our @ISA;
817		1001
818	our @REGISTRY;	1002	our @REGISTRY;
819		1003
820	our $WIN32;	1004	our $WIN32;
821		1005
822	BEGIN {	1006	BEGIN {
823	my $win32 = ! ! ($^O =~ /mswin32/i);	1007	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
824	eval "sub WIN32(){ $win32 }";	1008	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1009
		1010	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1011	if ${^TAINT};
825	}	1012	}
826		1013
827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1014	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
828		1015
829	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	1016	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1034	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1035	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1036	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
850	[Wx:: => AnyEvent::Impl::POE::],	1037	[Wx:: => AnyEvent::Impl::POE::],
851	[Prima:: => AnyEvent::Impl::POE::],	1038	[Prima:: => AnyEvent::Impl::POE::],
		1039	# IO::Async is just too broken - we would need workaorunds for its
		1040	# byzantine signal and broken child handling, among others.
		1041	# IO::Async is rather hard to detect, as it doesn't have any
		1042	# obvious default class.
		1043	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1044	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1045	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
852	);	1046	);
853		1047
854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1048	our %method = map +($_ => 1),
		1049	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
855		1050
856	our @post_detect;	1051	our @post_detect;
857		1052
858	sub post_detect(&) {	1053	sub post_detect(&) {
859	my ($cb) = @_;	1054	my ($cb) = @_;
…		…
864	1	1059	1
865	} else {	1060	} else {
866	push @post_detect, $cb;	1061	push @post_detect, $cb;
867		1062
868	defined wantarray	1063	defined wantarray
869	? bless \$cb, "AnyEvent::Util::PostDetect"	1064	? bless \$cb, "AnyEvent::Util::postdetect"
870	: ()	1065	: ()
871	}	1066	}
872	}	1067	}
873		1068
874	sub AnyEvent::Util::PostDetect::DESTROY {	1069	sub AnyEvent::Util::postdetect::DESTROY {
875	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1070	@post_detect = grep $_ != ${$_[0]}, @post_detect;
876	}	1071	}
877		1072
878	sub detect() {	1073	sub detect() {
879	unless ($MODEL) {	1074	unless ($MODEL) {
…		…
916	last;	1111	last;
917	}	1112	}
918	}	1113	}
919		1114
920	$MODEL	1115	$MODEL
921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1116	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
922	}	1117	}
923	}	1118	}
924		1119
		1120	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1121
925	unshift @ISA, $MODEL;	1122	unshift @ISA, $MODEL;
926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1123
		1124	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
927		1125
928	(shift @post_detect)->() while @post_detect;	1126	(shift @post_detect)->() while @post_detect;
929	}	1127	}
930		1128
931	$MODEL	1129	$MODEL
…		…
941		1139
942	my $class = shift;	1140	my $class = shift;
943	$class->$func (@_);	1141	$class->$func (@_);
944	}	1142	}
945		1143
		1144	# utility function to dup a filehandle. this is used by many backends
		1145	# to support binding more than one watcher per filehandle (they usually
		1146	# allow only one watcher per fd, so we dup it to get a different one).
		1147	sub _dupfh($$;$$) {
		1148	my ($poll, $fh, $r, $w) = @_;
		1149
		1150	# cygwin requires the fh mode to be matching, unix doesn't
		1151	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1152	: $poll eq "w" ? ($w, ">")
		1153	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1154
		1155	open my $fh2, "$mode&" . fileno $fh
		1156	or die "cannot dup() filehandle: $!,";
		1157
		1158	# we assume CLOEXEC is already set by perl in all important cases
		1159
		1160	($fh2, $rw)
		1161	}
		1162
946	package AnyEvent::Base;	1163	package AnyEvent::Base;
947		1164
948	# default implementation for now and time	1165	# default implementations for many methods
949		1166
950	use Time::HiRes ();	1167	BEGIN {
		1168	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1169	*_time = \&Time::HiRes::time;
		1170	# if (eval "use POSIX (); (POSIX::times())...
		1171	} else {
		1172	*_time = sub { time }; # epic fail
		1173	}
		1174	}
951		1175
952	sub time { Time::HiRes::time }	1176	sub time { _time }
953	sub now { Time::HiRes::time }	1177	sub now { _time }
		1178	sub now_update { }
954		1179
955	# default implementation for ->condvar	1180	# default implementation for ->condvar
956		1181
957	sub condvar {	1182	sub condvar {
958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1183	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
959	}	1184	}
960		1185
961	# default implementation for ->signal	1186	# default implementation for ->signal
962		1187
963	our %SIG_CB;	1188	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1189
		1190	sub _signal_exec {
		1191	sysread $SIGPIPE_R, my $dummy, 4;
		1192
		1193	while (%SIG_EV) {
		1194	for (keys %SIG_EV) {
		1195	delete $SIG_EV{$_};
		1196	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1197	}
		1198	}
		1199	}
964		1200
965	sub signal {	1201	sub signal {
966	my (undef, %arg) = @_;	1202	my (undef, %arg) = @_;
967		1203
		1204	unless ($SIGPIPE_R) {
		1205	require Fcntl;
		1206
		1207	if (AnyEvent::WIN32) {
		1208	require AnyEvent::Util;
		1209
		1210	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1211	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1212	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1213	} else {
		1214	pipe $SIGPIPE_R, $SIGPIPE_W;
		1215	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1216	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1217
		1218	# not strictly required, as $^F is normally 2, but let's make sure...
		1219	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1220	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1221	}
		1222
		1223	$SIGPIPE_R
		1224	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1225
		1226	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1227	}
		1228
968	my $signal = uc $arg{signal}	1229	my $signal = uc $arg{signal}
969	or Carp::croak "required option 'signal' is missing";	1230	or Carp::croak "required option 'signal' is missing";
970		1231
971	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1232	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
972	$SIG{$signal} \|\|= sub {	1233	$SIG{$signal} \|\|= sub {
973	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1234	local $!;
		1235	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1236	undef $SIG_EV{$signal};
974	};	1237	};
975		1238
976	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1239	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
977	}	1240	}
978		1241
979	sub AnyEvent::Base::Signal::DESTROY {	1242	sub AnyEvent::Base::signal::DESTROY {
980	my ($signal, $cb) = @{$_[0]};	1243	my ($signal, $cb) = @{$_[0]};
981		1244
982	delete $SIG_CB{$signal}{$cb};	1245	delete $SIG_CB{$signal}{$cb};
983		1246
		1247	# delete doesn't work with older perls - they then
		1248	# print weird messages, or just unconditionally exit
		1249	# instead of getting the default action.
984	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1250	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
985	}	1251	}
986		1252
987	# default implementation for ->child	1253	# default implementation for ->child
988		1254
989	our %PID_CB;	1255	our %PID_CB;
990	our $CHLD_W;	1256	our $CHLD_W;
991	our $CHLD_DELAY_W;	1257	our $CHLD_DELAY_W;
992	our $PID_IDLE;
993	our $WNOHANG;	1258	our $WNOHANG;
994		1259
995	sub _child_wait {	1260	sub _sigchld {
996	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1261	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
997	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1262	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
998	(values %{ $PID_CB{0} \|\| {} });	1263	(values %{ $PID_CB{0} \|\| {} });
999	}	1264	}
1000
1001	undef $PID_IDLE;
1002	}
1003
1004	sub _sigchld {
1005	# make sure we deliver these changes "synchronous" with the event loop.
1006	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1007	undef $CHLD_DELAY_W;
1008	&_child_wait;
1009	});
1010	}	1265	}
1011		1266
1012	sub child {	1267	sub child {
1013	my (undef, %arg) = @_;	1268	my (undef, %arg) = @_;
1014		1269
1015	defined (my $pid = $arg{pid} + 0)	1270	defined (my $pid = $arg{pid} + 0)
1016	or Carp::croak "required option 'pid' is missing";	1271	or Carp::croak "required option 'pid' is missing";
1017		1272
1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1273	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1019		1274
1020	unless ($WNOHANG) {
1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1275	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1022	}
1023		1276
1024	unless ($CHLD_W) {	1277	unless ($CHLD_W) {
1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1278	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1026	# child could be a zombie already, so make at least one round	1279	# child could be a zombie already, so make at least one round
1027	&_sigchld;	1280	&_sigchld;
1028	}	1281	}
1029		1282
1030	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1283	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1031	}	1284	}
1032		1285
1033	sub AnyEvent::Base::Child::DESTROY {	1286	sub AnyEvent::Base::child::DESTROY {
1034	my ($pid, $cb) = @{$_[0]};	1287	my ($pid, $cb) = @{$_[0]};
1035		1288
1036	delete $PID_CB{$pid}{$cb};	1289	delete $PID_CB{$pid}{$cb};
1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1290	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1038		1291
1039	undef $CHLD_W unless keys %PID_CB;	1292	undef $CHLD_W unless keys %PID_CB;
		1293	}
		1294
		1295	# idle emulation is done by simply using a timer, regardless
		1296	# of whether the process is idle or not, and not letting
		1297	# the callback use more than 50% of the time.
		1298	sub idle {
		1299	my (undef, %arg) = @_;
		1300
		1301	my ($cb, $w, $rcb) = $arg{cb};
		1302
		1303	$rcb = sub {
		1304	if ($cb) {
		1305	$w = _time;
		1306	&$cb;
		1307	$w = _time - $w;
		1308
		1309	# never use more then 50% of the time for the idle watcher,
		1310	# within some limits
		1311	$w = 0.0001 if $w < 0.0001;
		1312	$w = 5 if $w > 5;
		1313
		1314	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1315	} else {
		1316	# clean up...
		1317	undef $w;
		1318	undef $rcb;
		1319	}
		1320	};
		1321
		1322	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1323
		1324	bless \\$cb, "AnyEvent::Base::idle"
		1325	}
		1326
		1327	sub AnyEvent::Base::idle::DESTROY {
		1328	undef $${$_[0]};
1040	}	1329	}
1041		1330
1042	package AnyEvent::CondVar;	1331	package AnyEvent::CondVar;
1043		1332
1044	our @ISA = AnyEvent::CondVar::Base::;	1333	our @ISA = AnyEvent::CondVar::Base::;
…		…
1096	}	1385	}
1097		1386
1098	# undocumented/compatibility with pre-3.4	1387	# undocumented/compatibility with pre-3.4
1099	*broadcast = \&send;	1388	*broadcast = \&send;
1100	*wait = \&_wait;	1389	*wait = \&_wait;
		1390
		1391	=head1 ERROR AND EXCEPTION HANDLING
		1392
		1393	In general, AnyEvent does not do any error handling - it relies on the
		1394	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1395	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1396	checking of all AnyEvent methods, however, which is highly useful during
		1397	development.
		1398
		1399	As for exception handling (i.e. runtime errors and exceptions thrown while
		1400	executing a callback), this is not only highly event-loop specific, but
		1401	also not in any way wrapped by this module, as this is the job of the main
		1402	program.
		1403
		1404	The pure perl event loop simply re-throws the exception (usually
		1405	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1406	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1407	so on.
		1408
		1409	=head1 ENVIRONMENT VARIABLES
		1410
		1411	The following environment variables are used by this module or its
		1412	submodules.
		1413
		1414	Note that AnyEvent will remove I<all> environment variables starting with
		1415	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1416	enabled.
		1417
		1418	=over 4
		1419
		1420	=item C<PERL_ANYEVENT_VERBOSE>
		1421
		1422	By default, AnyEvent will be completely silent except in fatal
		1423	conditions. You can set this environment variable to make AnyEvent more
		1424	talkative.
		1425
		1426	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1427	conditions, such as not being able to load the event model specified by
		1428	C<PERL_ANYEVENT_MODEL>.
		1429
		1430	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1431	model it chooses.
		1432
		1433	=item C<PERL_ANYEVENT_STRICT>
		1434
		1435	AnyEvent does not do much argument checking by default, as thorough
		1436	argument checking is very costly. Setting this variable to a true value
		1437	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1438	check the arguments passed to most method calls. If it finds any problems,
		1439	it will croak.
		1440
		1441	In other words, enables "strict" mode.
		1442
		1443	Unlike C<use strict>, it is definitely recommended to keep it off in
		1444	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1445	developing programs can be very useful, however.
		1446
		1447	=item C<PERL_ANYEVENT_MODEL>
		1448
		1449	This can be used to specify the event model to be used by AnyEvent, before
		1450	auto detection and -probing kicks in. It must be a string consisting
		1451	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1452	and the resulting module name is loaded and if the load was successful,
		1453	used as event model. If it fails to load AnyEvent will proceed with
		1454	auto detection and -probing.
		1455
		1456	This functionality might change in future versions.
		1457
		1458	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1459	could start your program like this:
		1460
		1461	PERL_ANYEVENT_MODEL=Perl perl ...
		1462
		1463	=item C<PERL_ANYEVENT_PROTOCOLS>
		1464
		1465	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1466	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1467	of auto probing).
		1468
		1469	Must be set to a comma-separated list of protocols or address families,
		1470	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1471	used, and preference will be given to protocols mentioned earlier in the
		1472	list.
		1473
		1474	This variable can effectively be used for denial-of-service attacks
		1475	against local programs (e.g. when setuid), although the impact is likely
		1476	small, as the program has to handle conenction and other failures anyways.
		1477
		1478	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1479	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1480	- only support IPv4, never try to resolve or contact IPv6
		1481	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1482	IPv6, but prefer IPv6 over IPv4.
		1483
		1484	=item C<PERL_ANYEVENT_EDNS0>
		1485
		1486	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1487	for DNS. This extension is generally useful to reduce DNS traffic, but
		1488	some (broken) firewalls drop such DNS packets, which is why it is off by
		1489	default.
		1490
		1491	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1492	EDNS0 in its DNS requests.
		1493
		1494	=item C<PERL_ANYEVENT_MAX_FORKS>
		1495
		1496	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1497	will create in parallel.
		1498
		1499	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1500
		1501	The default value for the C<max_outstanding> parameter for the default DNS
		1502	resolver - this is the maximum number of parallel DNS requests that are
		1503	sent to the DNS server.
		1504
		1505	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1506
		1507	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1508	configuration) in the default resolver. When set to the empty string, no
		1509	default config will be used.
		1510
		1511	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1512
		1513	When neither C<ca_file> nor C<ca_path> was specified during
		1514	L<AnyEvent::TLS> context creation, and either of these environment
		1515	variables exist, they will be used to specify CA certificate locations
		1516	instead of a system-dependent default.
		1517
		1518	=back
1101		1519
1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1520	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1103		1521
1104	This is an advanced topic that you do not normally need to use AnyEvent in	1522	This is an advanced topic that you do not normally need to use AnyEvent in
1105	a module. This section is only of use to event loop authors who want to	1523	a module. This section is only of use to event loop authors who want to
…		…
1139		1557
1140	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1558	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1141	condition variables: code blocking while waiting for a condition will	1559	condition variables: code blocking while waiting for a condition will
1142	C<die>. This still works with most modules/usages, and blocking calls must	1560	C<die>. This still works with most modules/usages, and blocking calls must
1143	not be done in an interactive application, so it makes sense.	1561	not be done in an interactive application, so it makes sense.
1144
1145	=head1 ENVIRONMENT VARIABLES
1146
1147	The following environment variables are used by this module:
1148
1149	=over 4
1150
1151	=item C<PERL_ANYEVENT_VERBOSE>
1152
1153	By default, AnyEvent will be completely silent except in fatal
1154	conditions. You can set this environment variable to make AnyEvent more
1155	talkative.
1156
1157	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1158	conditions, such as not being able to load the event model specified by
1159	C<PERL_ANYEVENT_MODEL>.
1160
1161	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1162	model it chooses.
1163
1164	=item C<PERL_ANYEVENT_MODEL>
1165
1166	This can be used to specify the event model to be used by AnyEvent, before
1167	auto detection and -probing kicks in. It must be a string consisting
1168	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1169	and the resulting module name is loaded and if the load was successful,
1170	used as event model. If it fails to load AnyEvent will proceed with
1171	auto detection and -probing.
1172
1173	This functionality might change in future versions.
1174
1175	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1176	could start your program like this:
1177
1178	PERL_ANYEVENT_MODEL=Perl perl ...
1179
1180	=item C<PERL_ANYEVENT_PROTOCOLS>
1181
1182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1184	of auto probing).
1185
1186	Must be set to a comma-separated list of protocols or address families,
1187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1188	used, and preference will be given to protocols mentioned earlier in the
1189	list.
1190
1191	This variable can effectively be used for denial-of-service attacks
1192	against local programs (e.g. when setuid), although the impact is likely
1193	small, as the program has to handle connection errors already-
1194
1195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1197	- only support IPv4, never try to resolve or contact IPv6
1198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1199	IPv6, but prefer IPv6 over IPv4.
1200
1201	=item C<PERL_ANYEVENT_EDNS0>
1202
1203	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1204	for DNS. This extension is generally useful to reduce DNS traffic, but
1205	some (broken) firewalls drop such DNS packets, which is why it is off by
1206	default.
1207
1208	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1209	EDNS0 in its DNS requests.
1210
1211	=item C<PERL_ANYEVENT_MAX_FORKS>
1212
1213	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1214	will create in parallel.
1215
1216	=back
1217		1562
1218	=head1 EXAMPLE PROGRAM	1563	=head1 EXAMPLE PROGRAM
1219		1564
1220	The following program uses an I/O watcher to read data from STDIN, a timer	1565	The following program uses an I/O watcher to read data from STDIN, a timer
1221	to display a message once per second, and a condition variable to quit the	1566	to display a message once per second, and a condition variable to quit the
…		…
1415	watcher.	1760	watcher.
1416		1761
1417	=head3 Results	1762	=head3 Results
1418		1763
1419	name watchers bytes create invoke destroy comment	1764	name watchers bytes create invoke destroy comment
1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1765	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1766	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1767	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1768	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1769	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1770	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1771	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1772	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1773	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1774	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1775	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1776	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1430		1777
1431	=head3 Discussion	1778	=head3 Discussion
1432		1779
1433	The benchmark does I<not> measure scalability of the event loop very	1780	The benchmark does I<not> measure scalability of the event loop very
1434	well. For example, a select-based event loop (such as the pure perl one)	1781	well. For example, a select-based event loop (such as the pure perl one)
…		…
1459	performance becomes really bad with lots of file descriptors (and few of	1806	performance becomes really bad with lots of file descriptors (and few of
1460	them active), of course, but this was not subject of this benchmark.	1807	them active), of course, but this was not subject of this benchmark.
1461		1808
1462	The C<Event> module has a relatively high setup and callback invocation	1809	The C<Event> module has a relatively high setup and callback invocation
1463	cost, but overall scores in on the third place.	1810	cost, but overall scores in on the third place.
		1811
		1812	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1813	when using its pure perl backend.
1464		1814
1465	C<Glib>'s memory usage is quite a bit higher, but it features a	1815	C<Glib>'s memory usage is quite a bit higher, but it features a
1466	faster callback invocation and overall ends up in the same class as	1816	faster callback invocation and overall ends up in the same class as
1467	C<Event>. However, Glib scales extremely badly, doubling the number of	1817	C<Event>. However, Glib scales extremely badly, doubling the number of
1468	watchers increases the processing time by more than a factor of four,	1818	watchers increases the processing time by more than a factor of four,
…		…
1546	it to another server. This includes deleting the old timeout and creating	1896	it to another server. This includes deleting the old timeout and creating
1547	a new one that moves the timeout into the future.	1897	a new one that moves the timeout into the future.
1548		1898
1549	=head3 Results	1899	=head3 Results
1550		1900
1551	name sockets create request	1901	name sockets create request
1552	EV 20000 69.01 11.16	1902	EV 20000 69.01 11.16
1553	Perl 20000 73.32 35.87	1903	Perl 20000 73.32 35.87
		1904	IOAsync 20000 157.00 98.14 epoll
		1905	IOAsync 20000 159.31 616.06 poll
1554	Event 20000 212.62 257.32	1906	Event 20000 212.62 257.32
1555	Glib 20000 651.16 1896.30	1907	Glib 20000 651.16 1896.30
1556	POE 20000 349.67 12317.24 uses POE::Loop::Event	1908	POE 20000 349.67 12317.24 uses POE::Loop::Event
1557		1909
1558	=head3 Discussion	1910	=head3 Discussion
1559		1911
1560	This benchmark I<does> measure scalability and overall performance of the	1912	This benchmark I<does> measure scalability and overall performance of the
1561	particular event loop.	1913	particular event loop.
…		…
1563	EV is again fastest. Since it is using epoll on my system, the setup time	1915	EV is again fastest. Since it is using epoll on my system, the setup time
1564	is relatively high, though.	1916	is relatively high, though.
1565		1917
1566	Perl surprisingly comes second. It is much faster than the C-based event	1918	Perl surprisingly comes second. It is much faster than the C-based event
1567	loops Event and Glib.	1919	loops Event and Glib.
		1920
		1921	IO::Async performs very well when using its epoll backend, and still quite
		1922	good compared to Glib when using its pure perl backend.
1568		1923
1569	Event suffers from high setup time as well (look at its code and you will	1924	Event suffers from high setup time as well (look at its code and you will
1570	understand why). Callback invocation also has a high overhead compared to	1925	understand why). Callback invocation also has a high overhead compared to
1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1926	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1572	uses select or poll in basically all documented configurations.	1927	uses select or poll in basically all documented configurations.
…		…
1635	=item * C-based event loops perform very well with small number of	1990	=item * C-based event loops perform very well with small number of
1636	watchers, as the management overhead dominates.	1991	watchers, as the management overhead dominates.
1637		1992
1638	=back	1993	=back
1639		1994
		1995	=head2 THE IO::Lambda BENCHMARK
		1996
		1997	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1998	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1999	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2000	shouldn't come as a surprise to anybody). As such, the benchmark is
		2001	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2002	very optimal. But how would AnyEvent compare when used without the extra
		2003	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2004
		2005	The benchmark itself creates an echo-server, and then, for 500 times,
		2006	connects to the echo server, sends a line, waits for the reply, and then
		2007	creates the next connection. This is a rather bad benchmark, as it doesn't
		2008	test the efficiency of the framework or much non-blocking I/O, but it is a
		2009	benchmark nevertheless.
		2010
		2011	name runtime
		2012	Lambda/select 0.330 sec
		2013	+ optimized 0.122 sec
		2014	Lambda/AnyEvent 0.327 sec
		2015	+ optimized 0.138 sec
		2016	Raw sockets/select 0.077 sec
		2017	POE/select, components 0.662 sec
		2018	POE/select, raw sockets 0.226 sec
		2019	POE/select, optimized 0.404 sec
		2020
		2021	AnyEvent/select/nb 0.085 sec
		2022	AnyEvent/EV/nb 0.068 sec
		2023	+state machine 0.134 sec
		2024
		2025	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2026	benchmarks actually make blocking connects and use 100% blocking I/O,
		2027	defeating the purpose of an event-based solution. All of the newly
		2028	written AnyEvent benchmarks use 100% non-blocking connects (using
		2029	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2030	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2031	generally require a lot more bookkeeping and event handling than blocking
		2032	connects (which involve a single syscall only).
		2033
		2034	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2035	offers similar expressive power as POE and IO::Lambda, using conventional
		2036	Perl syntax. This means that both the echo server and the client are 100%
		2037	non-blocking, further placing it at a disadvantage.
		2038
		2039	As you can see, the AnyEvent + EV combination even beats the
		2040	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2041	backend easily beats IO::Lambda and POE.
		2042
		2043	And even the 100% non-blocking version written using the high-level (and
		2044	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2045	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2046	in a non-blocking way.
		2047
		2048	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2049	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2050	part of the IO::lambda distribution and were used without any changes.
		2051
		2052
		2053	=head1 SIGNALS
		2054
		2055	AnyEvent currently installs handlers for these signals:
		2056
		2057	=over 4
		2058
		2059	=item SIGCHLD
		2060
		2061	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2062	emulation for event loops that do not support them natively. Also, some
		2063	event loops install a similar handler.
		2064
		2065	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2066	reset it to default, to avoid losing child exit statuses.
		2067
		2068	=item SIGPIPE
		2069
		2070	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2071	when AnyEvent gets loaded.
		2072
		2073	The rationale for this is that AnyEvent users usually do not really depend
		2074	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2075	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2076	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2077	some random socket.
		2078
		2079	The rationale for installing a no-op handler as opposed to ignoring it is
		2080	that this way, the handler will be restored to defaults on exec.
		2081
		2082	Feel free to install your own handler, or reset it to defaults.
		2083
		2084	=back
		2085
		2086	=cut
		2087
		2088	undef $SIG{CHLD}
		2089	if $SIG{CHLD} eq 'IGNORE';
		2090
		2091	$SIG{PIPE} = sub { }
		2092	unless defined $SIG{PIPE};
1640		2093
1641	=head1 FORK	2094	=head1 FORK
1642		2095
1643	Most event libraries are not fork-safe. The ones who are usually are	2096	Most event libraries are not fork-safe. The ones who are usually are
1644	because they rely on inefficient but fork-safe C<select> or C<poll>	2097	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1664		2117
1665	use AnyEvent;	2118	use AnyEvent;
1666		2119
1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2120	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1668	be used to probe what backend is used and gain other information (which is	2121	be used to probe what backend is used and gain other information (which is
1669	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2122	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2123	$ENV{PERL_ANYEVENT_STRICT}.
		2124
		2125	Note that AnyEvent will remove I<all> environment variables starting with
		2126	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2127	enabled.
		2128
		2129
		2130	=head1 BUGS
		2131
		2132	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2133	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2134	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2135	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2136	pronounced).
1670		2137
1671		2138
1672	=head1 SEE ALSO	2139	=head1 SEE ALSO
1673		2140
1674	Utility functions: L<AnyEvent::Util>.	2141	Utility functions: L<AnyEvent::Util>.

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.152 by root, Tue Jun 3 09:02:46 2008 UTC vs. Revision 1.228 by root, Wed Jul 8 01:11:12 2009 UTC

Diff Legend

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.152 by root, Tue Jun 3 09:02:46 2008 UTC vs.
Revision 1.228 by root, Wed Jul 8 01:11:12 2009 UTC