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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC vs.
Revision 1.186 by root, Mon Oct 27 02:58:19 2008 UTC

…		…
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub { ... });
12	...
13	});
14		12
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		15
		16	print AnyEvent->now; # prints current event loop time
		17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		18
		19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		20
		21	my $w = AnyEvent->child (pid => $pid, cb => sub {
		22	my ($pid, $status) = @_;
16	...	23	...
17	});	24	});
18		25
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	26	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	27	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	28	$w->recv; # enters "main loop" till $condvar gets ->send
		29	# use a condvar in callback mode:
		30	$w->cb (sub { $_[0]->recv });
22		31
23	=head1 INTRODUCTION/TUTORIAL	32	=head1 INTRODUCTION/TUTORIAL
24		33
25	This manpage is mainly a reference manual. If you are interested	34	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	35	in a tutorial or some gentle introduction, have a look at the
…		…
33		42
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	43	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	44	policy> and AnyEvent is I<small and efficient>.
36		45
37	First and foremost, I<AnyEvent is not an event model> itself, it only	46	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	47	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	48	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,	49	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	50	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	51	cannot change this, but it can hide the differences between those event
		52	loops.
43		53
44	The goal of AnyEvent is to offer module authors the ability to do event	54	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	55	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	56	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	57	module users into the same thing by forcing them to use the same event
48	model you use.	58	model you use.
49		59
50	For modules like POE or IO::Async (which is a total misnomer as it is	60	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	61	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	62	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	63	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	64	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.	65	module are I<also> forced to use the same event loop you use.
56		66
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	67	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	68	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	69	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	70	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	71	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	72	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	73	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	74	to AnyEvent, too, so it is future-proof).
65		75
66	In addition to being free of having to use I<the one and only true event	76	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	77	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	78	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	79	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
152	=head2 I/O WATCHERS	162	=head2 I/O WATCHERS
153		163
154	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
155	with the following mandatory key-value pairs as arguments:	165	with the following mandatory key-value pairs as arguments:
156		166
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events
158	for events. C<poll> must be a string that is either C<r> or C<w>,	168	(AnyEvent might or might not keep a reference to this file handle). C<poll>
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	169	must be a string that is either C<r> or C<w>, which creates a watcher
160	respectively. C<cb> is the callback to invoke each time the file handle	170	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the
161	becomes ready.	171	callback to invoke each time the file handle becomes ready.
162		172
163	Although the callback might get passed parameters, their value and	173	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	174	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	175	callbacks cannot use arguments passed to I/O watcher callbacks.
166		176
…		…
193	Although the callback might get passed parameters, their value and	203	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	204	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	205	callbacks cannot use arguments passed to time watcher callbacks.
196		206
197	The callback will normally be invoked once only. If you specify another	207	The callback will normally be invoked once only. If you specify another
198	parameter, C<interval>, as a positive number, then the callback will be	208	parameter, C<interval>, as a strictly positive number (> 0), then the
199	invoked regularly at that interval (in fractional seconds) after the first	209	callback will be invoked regularly at that interval (in fractional
200	invocation.	210	seconds) after the first invocation. If C<interval> is specified with a
		211	false value, then it is treated as if it were missing.
201		212
202	The callback will be rescheduled before invoking the callback, but no	213	The callback will be rescheduled before invoking the callback, but no
203	attempt is done to avoid timer drift in most backends, so the interval is	214	attempt is done to avoid timer drift in most backends, so the interval is
204	only approximate.	215	only approximate.
205		216
…		…
302	=back	313	=back
303		314
304	=head2 SIGNAL WATCHERS	315	=head2 SIGNAL WATCHERS
305		316
306	You can watch for signals using a signal watcher, C<signal> is the signal	317	You can watch for signals using a signal watcher, C<signal> is the signal
307	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	318	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
308	be invoked whenever a signal occurs.	319	callback to be invoked whenever a signal occurs.
309		320
310	Although the callback might get passed parameters, their value and	321	Although the callback might get passed parameters, their value and
311	presence is undefined and you cannot rely on them. Portable AnyEvent	322	presence is undefined and you cannot rely on them. Portable AnyEvent
312	callbacks cannot use arguments passed to signal watcher callbacks.	323	callbacks cannot use arguments passed to signal watcher callbacks.
313		324
…		…
329	=head2 CHILD PROCESS WATCHERS	340	=head2 CHILD PROCESS WATCHERS
330		341
331	You can also watch on a child process exit and catch its exit status.	342	You can also watch on a child process exit and catch its exit status.
332		343
333	The child process is specified by the C<pid> argument (if set to C<0>, it	344	The child process is specified by the C<pid> argument (if set to C<0>, it
334	watches for any child process exit). The watcher will trigger as often	345	watches for any child process exit). The watcher will triggered only when
335	as status change for the child are received. This works by installing a	346	the child process has finished and an exit status is available, not on
336	signal handler for C<SIGCHLD>. The callback will be called with the pid	347	any trace events (stopped/continued).
337	and exit status (as returned by waitpid), so unlike other watcher types,	348
338	you I<can> rely on child watcher callback arguments.	349	The callback will be called with the pid and exit status (as returned by
		350	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		351	callback arguments.
		352
		353	This watcher type works by installing a signal handler for C<SIGCHLD>,
		354	and since it cannot be shared, nothing else should use SIGCHLD or reap
		355	random child processes (waiting for specific child processes, e.g. inside
		356	C<system>, is just fine).
339		357
340	There is a slight catch to child watchers, however: you usually start them	358	There is a slight catch to child watchers, however: you usually start them
341	I<after> the child process was created, and this means the process could	359	I<after> the child process was created, and this means the process could
342	have exited already (and no SIGCHLD will be sent anymore).	360	have exited already (and no SIGCHLD will be sent anymore).
343		361
…		…
379	The instrument to do that is called a "condition variable", so called	397	The instrument to do that is called a "condition variable", so called
380	because they represent a condition that must become true.	398	because they represent a condition that must become true.
381		399
382	Condition variables can be created by calling the C<< AnyEvent->condvar	400	Condition variables can be created by calling the C<< AnyEvent->condvar
383	>> method, usually without arguments. The only argument pair allowed is	401	>> method, usually without arguments. The only argument pair allowed is
		402
384	C<cb>, which specifies a callback to be called when the condition variable	403	C<cb>, which specifies a callback to be called when the condition variable
385	becomes true.	404	becomes true, with the condition variable as the first argument (but not
		405	the results).
386		406
387	After creation, the condition variable is "false" until it becomes "true"	407	After creation, the condition variable is "false" until it becomes "true"
388	by calling the C<send> method (or calling the condition variable as if it	408	by calling the C<send> method (or calling the condition variable as if it
389	were a callback, read about the caveats in the description for the C<<	409	were a callback, read about the caveats in the description for the C<<
390	->send >> method).	410	->send >> method).
…		…
446		466
447	my $done = AnyEvent->condvar;	467	my $done = AnyEvent->condvar;
448	my $delay = AnyEvent->timer (after => 5, cb => $done);	468	my $delay = AnyEvent->timer (after => 5, cb => $done);
449	$done->recv;	469	$done->recv;
450		470
		471	Example: Imagine an API that returns a condvar and doesn't support
		472	callbacks. This is how you make a synchronous call, for example from
		473	the main program:
		474
		475	use AnyEvent::CouchDB;
		476
		477	...
		478
		479	my @info = $couchdb->info->recv;
		480
		481	And this is how you would just ste a callback to be called whenever the
		482	results are available:
		483
		484	$couchdb->info->cb (sub {
		485	my @info = $_[0]->recv;
		486	});
		487
451	=head3 METHODS FOR PRODUCERS	488	=head3 METHODS FOR PRODUCERS
452		489
453	These methods should only be used by the producing side, i.e. the	490	These methods should only be used by the producing side, i.e. the
454	code/module that eventually sends the signal. Note that it is also	491	code/module that eventually sends the signal. Note that it is also
455	the producer side which creates the condvar in most cases, but it isn't	492	the producer side which creates the condvar in most cases, but it isn't
…		…
588	=item $bool = $cv->ready	625	=item $bool = $cv->ready
589		626
590	Returns true when the condition is "true", i.e. whether C<send> or	627	Returns true when the condition is "true", i.e. whether C<send> or
591	C<croak> have been called.	628	C<croak> have been called.
592		629
593	=item $cb = $cv->cb ([new callback])	630	=item $cb = $cv->cb ($cb->($cv))
594		631
595	This is a mutator function that returns the callback set and optionally	632	This is a mutator function that returns the callback set and optionally
596	replaces it before doing so.	633	replaces it before doing so.
597		634
598	The callback will be called when the condition becomes "true", i.e. when	635	The callback will be called when the condition becomes "true", i.e. when
…		…
788	=item L<AnyEvent::IGS>	825	=item L<AnyEvent::IGS>
789		826
790	A non-blocking interface to the Internet Go Server protocol (used by	827	A non-blocking interface to the Internet Go Server protocol (used by
791	L<App::IGS>).	828	L<App::IGS>).
792		829
793	=item L<Net::IRC3>	830	=item L<AnyEvent::IRC>
794		831
795	AnyEvent based IRC client module family.	832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
796		833
797	=item L<Net::XMPP2>	834	=item L<Net::XMPP2>
798		835
799	AnyEvent based XMPP (Jabber protocol) module family.	836	AnyEvent based XMPP (Jabber protocol) module family.
800		837
…		…
820	=cut	857	=cut
821		858
822	package AnyEvent;	859	package AnyEvent;
823		860
824	no warnings;	861	no warnings;
825	use strict;	862	use strict qw(vars subs);
826		863
827	use Carp;	864	use Carp;
828		865
829	our $VERSION = 4.2;	866	our $VERSION = 4.3;
830	our $MODEL;	867	our $MODEL;
831		868
832	our $AUTOLOAD;	869	our $AUTOLOAD;
833	our @ISA;	870	our @ISA;
834		871
…		…
937	$MODEL	974	$MODEL
938	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
939	}	976	}
940	}	977	}
941		978
		979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		980
942	unshift @ISA, $MODEL;	981	unshift @ISA, $MODEL;
943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	982
		983	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
944		984
945	(shift @post_detect)->() while @post_detect;	985	(shift @post_detect)->() while @post_detect;
946	}	986	}
947		987
948	$MODEL	988	$MODEL
…		…
958		998
959	my $class = shift;	999	my $class = shift;
960	$class->$func (@_);	1000	$class->$func (@_);
961	}	1001	}
962		1002
		1003	# utility function to dup a filehandle. this is used by many backends
		1004	# to support binding more than one watcher per filehandle (they usually
		1005	# allow only one watcher per fd, so we dup it to get a different one).
		1006	sub _dupfh($$$$) {
		1007	my ($poll, $fh, $r, $w) = @_;
		1008
		1009	require Fcntl;
		1010
		1011	# cygwin requires the fh mode to be matching, unix doesn't
		1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1013	: $poll eq "w" ? ($w, ">")
		1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1015
		1016	open my $fh2, "$mode&" . fileno $fh
		1017	or die "cannot dup() filehandle: $!";
		1018
		1019	# we assume CLOEXEC is already set by perl in all important cases
		1020
		1021	($fh2, $rw)
		1022	}
		1023
963	package AnyEvent::Base;	1024	package AnyEvent::Base;
964		1025
965	# default implementation for now and time	1026	# default implementation for now and time
966		1027
967	use Time::HiRes ();	1028	BEGIN {
		1029	if (eval "use Time::HiRes (); time (); 1") {
		1030	*_time = \&Time::HiRes::time;
		1031	# if (eval "use POSIX (); (POSIX::times())...
		1032	} else {
		1033	*_time = sub { time }; # epic fail
		1034	}
		1035	}
968		1036
969	sub time { Time::HiRes::time }	1037	sub time { _time }
970	sub now { Time::HiRes::time }	1038	sub now { _time }
971		1039
972	# default implementation for ->condvar	1040	# default implementation for ->condvar
973		1041
974	sub condvar {	1042	sub condvar {
975	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
…		…
1114		1182
1115	# undocumented/compatibility with pre-3.4	1183	# undocumented/compatibility with pre-3.4
1116	*broadcast = \&send;	1184	*broadcast = \&send;
1117	*wait = \&_wait;	1185	*wait = \&_wait;
1118		1186
		1187	=head1 ERROR AND EXCEPTION HANDLING
		1188
		1189	In general, AnyEvent does not do any error handling - it relies on the
		1190	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1191	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1192	checking of all AnyEvent methods, however, which is highly useful during
		1193	development.
		1194
		1195	As for exception handling (i.e. runtime errors and exceptions thrown while
		1196	executing a callback), this is not only highly event-loop specific, but
		1197	also not in any way wrapped by this module, as this is the job of the main
		1198	program.
		1199
		1200	The pure perl event loop simply re-throws the exception (usually
		1201	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1202	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1203	so on.
		1204
		1205	=head1 ENVIRONMENT VARIABLES
		1206
		1207	The following environment variables are used by this module or its
		1208	submodules:
		1209
		1210	=over 4
		1211
		1212	=item C<PERL_ANYEVENT_VERBOSE>
		1213
		1214	By default, AnyEvent will be completely silent except in fatal
		1215	conditions. You can set this environment variable to make AnyEvent more
		1216	talkative.
		1217
		1218	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1219	conditions, such as not being able to load the event model specified by
		1220	C<PERL_ANYEVENT_MODEL>.
		1221
		1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1223	model it chooses.
		1224
		1225	=item C<PERL_ANYEVENT_STRICT>
		1226
		1227	AnyEvent does not do much argument checking by default, as thorough
		1228	argument checking is very costly. Setting this variable to a true value
		1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1230	check the arguments passed to most method calls. If it finds any problems
		1231	it will croak.
		1232
		1233	In other words, enables "strict" mode.
		1234
		1235	Unlike C<use strict>, it is definitely recommended ot keep it off in
		1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1237	developing programs can be very useful, however.
		1238
		1239	=item C<PERL_ANYEVENT_MODEL>
		1240
		1241	This can be used to specify the event model to be used by AnyEvent, before
		1242	auto detection and -probing kicks in. It must be a string consisting
		1243	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1244	and the resulting module name is loaded and if the load was successful,
		1245	used as event model. If it fails to load AnyEvent will proceed with
		1246	auto detection and -probing.
		1247
		1248	This functionality might change in future versions.
		1249
		1250	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1251	could start your program like this:
		1252
		1253	PERL_ANYEVENT_MODEL=Perl perl ...
		1254
		1255	=item C<PERL_ANYEVENT_PROTOCOLS>
		1256
		1257	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1258	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1259	of auto probing).
		1260
		1261	Must be set to a comma-separated list of protocols or address families,
		1262	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1263	used, and preference will be given to protocols mentioned earlier in the
		1264	list.
		1265
		1266	This variable can effectively be used for denial-of-service attacks
		1267	against local programs (e.g. when setuid), although the impact is likely
		1268	small, as the program has to handle connection errors already-
		1269
		1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1272	- only support IPv4, never try to resolve or contact IPv6
		1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1274	IPv6, but prefer IPv6 over IPv4.
		1275
		1276	=item C<PERL_ANYEVENT_EDNS0>
		1277
		1278	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1279	for DNS. This extension is generally useful to reduce DNS traffic, but
		1280	some (broken) firewalls drop such DNS packets, which is why it is off by
		1281	default.
		1282
		1283	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1284	EDNS0 in its DNS requests.
		1285
		1286	=item C<PERL_ANYEVENT_MAX_FORKS>
		1287
		1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1289	will create in parallel.
		1290
		1291	=back
		1292
1119	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1120		1294
1121	This is an advanced topic that you do not normally need to use AnyEvent in	1295	This is an advanced topic that you do not normally need to use AnyEvent in
1122	a module. This section is only of use to event loop authors who want to	1296	a module. This section is only of use to event loop authors who want to
1123	provide AnyEvent compatibility.	1297	provide AnyEvent compatibility.
…		…
1156		1330
1157	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1331	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1158	condition variables: code blocking while waiting for a condition will	1332	condition variables: code blocking while waiting for a condition will
1159	C<die>. This still works with most modules/usages, and blocking calls must	1333	C<die>. This still works with most modules/usages, and blocking calls must
1160	not be done in an interactive application, so it makes sense.	1334	not be done in an interactive application, so it makes sense.
1161
1162	=head1 ENVIRONMENT VARIABLES
1163
1164	The following environment variables are used by this module:
1165
1166	=over 4
1167
1168	=item C<PERL_ANYEVENT_VERBOSE>
1169
1170	By default, AnyEvent will be completely silent except in fatal
1171	conditions. You can set this environment variable to make AnyEvent more
1172	talkative.
1173
1174	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1175	conditions, such as not being able to load the event model specified by
1176	C<PERL_ANYEVENT_MODEL>.
1177
1178	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1179	model it chooses.
1180
1181	=item C<PERL_ANYEVENT_MODEL>
1182
1183	This can be used to specify the event model to be used by AnyEvent, before
1184	auto detection and -probing kicks in. It must be a string consisting
1185	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1186	and the resulting module name is loaded and if the load was successful,
1187	used as event model. If it fails to load AnyEvent will proceed with
1188	auto detection and -probing.
1189
1190	This functionality might change in future versions.
1191
1192	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1193	could start your program like this:
1194
1195	PERL_ANYEVENT_MODEL=Perl perl ...
1196
1197	=item C<PERL_ANYEVENT_PROTOCOLS>
1198
1199	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1200	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1201	of auto probing).
1202
1203	Must be set to a comma-separated list of protocols or address families,
1204	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1205	used, and preference will be given to protocols mentioned earlier in the
1206	list.
1207
1208	This variable can effectively be used for denial-of-service attacks
1209	against local programs (e.g. when setuid), although the impact is likely
1210	small, as the program has to handle connection errors already-
1211
1212	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1213	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1214	- only support IPv4, never try to resolve or contact IPv6
1215	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1216	IPv6, but prefer IPv6 over IPv4.
1217
1218	=item C<PERL_ANYEVENT_EDNS0>
1219
1220	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1221	for DNS. This extension is generally useful to reduce DNS traffic, but
1222	some (broken) firewalls drop such DNS packets, which is why it is off by
1223	default.
1224
1225	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1226	EDNS0 in its DNS requests.
1227
1228	=item C<PERL_ANYEVENT_MAX_FORKS>
1229
1230	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1231	will create in parallel.
1232
1233	=back
1234		1335
1235	=head1 EXAMPLE PROGRAM	1336	=head1 EXAMPLE PROGRAM
1236		1337
1237	The following program uses an I/O watcher to read data from STDIN, a timer	1338	The following program uses an I/O watcher to read data from STDIN, a timer
1238	to display a message once per second, and a condition variable to quit the	1339	to display a message once per second, and a condition variable to quit the
…		…
1432	watcher.	1533	watcher.
1433		1534
1434	=head3 Results	1535	=head3 Results
1435		1536
1436	name watchers bytes create invoke destroy comment	1537	name watchers bytes create invoke destroy comment
1437	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1538	EV/EV 400000 224 0.47 0.43 0.27 EV native interface
1438	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1539	EV/Any 100000 224 2.88 0.44 0.27 EV + AnyEvent watchers
1439	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1540	CoroEV/Any 100000 224 2.85 0.45 0.28 coroutines + Coro::Signal
1440	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1541	Perl/Any 100000 452 4.14 0.75 0.99 pure perl implementation
1441	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1542	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1442	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1543	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
1443	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1544	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1444	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1545	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1445	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1546	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1446	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1547	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1447		1548
1448	=head3 Discussion	1549	=head3 Discussion
1449		1550
1450	The benchmark does I<not> measure scalability of the event loop very	1551	The benchmark does I<not> measure scalability of the event loop very
1451	well. For example, a select-based event loop (such as the pure perl one)	1552	well. For example, a select-based event loop (such as the pure perl one)
…		…
1653	watchers, as the management overhead dominates.	1754	watchers, as the management overhead dominates.
1654		1755
1655	=back	1756	=back
1656		1757
1657		1758
		1759	=head1 SIGNALS
		1760
		1761	AnyEvent currently installs handlers for these signals:
		1762
		1763	=over 4
		1764
		1765	=item SIGCHLD
		1766
		1767	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		1768	emulation for event loops that do not support them natively. Also, some
		1769	event loops install a similar handler.
		1770
		1771	=item SIGPIPE
		1772
		1773	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		1774	when AnyEvent gets loaded.
		1775
		1776	The rationale for this is that AnyEvent users usually do not really depend
		1777	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		1778	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		1779	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		1780	some random socket.
		1781
		1782	The rationale for installing a no-op handler as opposed to ignoring it is
		1783	that this way, the handler will be restored to defaults on exec.
		1784
		1785	Feel free to install your own handler, or reset it to defaults.
		1786
		1787	=back
		1788
		1789	=cut
		1790
		1791	$SIG{PIPE} = sub { }
		1792	unless defined $SIG{PIPE};
		1793
		1794
1658	=head1 FORK	1795	=head1 FORK
1659		1796
1660	Most event libraries are not fork-safe. The ones who are usually are	1797	Most event libraries are not fork-safe. The ones who are usually are
1661	because they rely on inefficient but fork-safe C<select> or C<poll>	1798	because they rely on inefficient but fork-safe C<select> or C<poll>
1662	calls. Only L<EV> is fully fork-aware.	1799	calls. Only L<EV> is fully fork-aware.
…		…
1681		1818
1682	use AnyEvent;	1819	use AnyEvent;
1683		1820
1684	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	1821	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1685	be used to probe what backend is used and gain other information (which is	1822	be used to probe what backend is used and gain other information (which is
1686	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	1823	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		1824	$ENV{PERL_ANYEGENT_STRICT}.
1687		1825
1688		1826
1689	=head1 BUGS	1827	=head1 BUGS
1690		1828
1691	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	1829	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC vs. Revision 1.186 by root, Mon Oct 27 02:58:19 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC vs.
Revision 1.186 by root, Mon Oct 27 02:58:19 2008 UTC